Finnish reference waters for solubility, sorption and diffusion studies

POSIVA OY

Working Report 98-61

Finnish reference waters for solubility, sorption and

diffusion studies

Ulla Vuorinen

Margit Snellman

December 1998

Mikonkatu 15 A, FIN-001 00 HELSINKI, FINLAND

Tel. +358-9-2280 30

Fax +358-9-2280 3719



diffusion studies

Ulla Vuorinen

Margit Snellman

December 1998

----------------------··-~--·-. ----


FINNISH REFERENCE WATERS FOR SOLUBILITY, SORPTION AND DIFFUSION STUDIES.

PARTICIPATING ORGANIZATIONS:

CONTRACTOR:

CONTRACT NUMBER:

CONTRACTOR'S CONTACT PERSON:

VTT Chemical Technology P.O.Box 1404 FIN -02044 VTT

Posiva Oy Mikonkatu 15 A FIN -00100 Helsinki

Posiva Oy Mikonkatu 15 A FIN -00100 Helsinki

9649/98/MVS

~ i-~ ______ Mar~ellman, Posiva Oy

~~--~ ...... _._ CONSULTANT'S CONTACT PERSONS:

AUTHORS:

ACCEPTED:

Ulla Vuorinen, VTT Chemical Technology

Ulla Vuorinen Margit Snellman

Arto Muurinen VT: Che~alT~~hnology ~11/W~~-

Aimo Hautoj arvi Posiva Oy

~ ...

1). 7. -1f



diffusion studies

Ulla Vuorinen

VTT Chemical Technology

Margit Snellman

Posiva Oy

December 1998

Working Reports contain information on work in progress

or pending completion.

FINNISH REFERENCE WATERS FOR SOLUBILITY, SORPTION AND DIFFUSION STUDIES

ABSTRACT

In the assessment of the safety of spent fuel disposal, the essential parameters to consider are the solubilities of the radionuclides possibly released. Solubilities are estimated in Finnish groundwater conditions, which have been investigated at four investigation sites: Olkiluoto, Kivetty, Romuvaara and Hastholmen. Different types of groundwater have been encountered at the sites including fresh, brackish, saline and highly saline groundwater, which is almost brine. The solubility of elements depends on the composition of the dissolving water and thus for the estimation of solubility values for the safety assessment TILA-99, different types of reference waters were defined that correspond to Finnish conditions.

The far-field reference waters chosen for estimating the solubilities for TILA-99 are based on the groundwater data obtained up to early 1998 from the four investigation sites. A summary of the groundwater data is presented. In addition to the far-field waters also near-field waters were defined based on the effects brought about in experimental studies of bentonite interaction with different types of groundwater. Additionally, the pH and carbonate equilibrium as well as the redox conditions were evaluated by modelling using the EQ3/6 code.

Besides the reference waters for the safety assessment, another category of reference waters is also briefly discussed, namely the synthetic reference groundwaters, which are needed in various experimental studies to be conducted in repeatable, well-defined conditions. A short summary of the compositions and the preparation of the synthetic reference waters is presented.

Keywords: reference waters, groundwater, synthetic waters, fresh, saline, brackish, brine, near-field, bentonite, redox, pH

SUOMALAISET REFERENSSIVEDET LIUKOISUUS-, SORPTIO- JA DIFFUUSIOTUTKIMUKSIA VARTEN

TIIVISTELMA

Arvioitaessa kaytetyn polttoaineen loppusijoituksen turvallisuutta keskeisia parametreja ovat polttoaineesta mahdollisesti vapautuvien radionuklidien liukoisuusarvot. Liukoisuuksia arvioidaan suomalaisissa pohjavesiolosuhteissa, joita on tutkittu neljalla eri tutkimusalueella; Olkiluoto, Kivetty, Romuvaara ja Hastholmen. Nailta tutkimuspaikoilta on tavattu eri tyyppisia pohjavesia; makeita vesia, murtovesityyppisia vesia, suolaisia vesia ja erittain suolaisia vesia. Alkuaineiden liukoisuudet riippuvat liuottavan veden koostumuksesta, joten turvallisuusanalyysin TILA-99 liukoisuustarkastelua varten maariteltiin erityyppiset Suomen olosuhteita vastaavat referenssi vedet.

Tassa raportissa esitetaan yhteenvetona neljan tutkimuspaikan erityyppisten pohjavesien koostumukset perustuen vuoden 1998 alkupuoleen mennessa saatuihin pohjavesianalyysitietoihin. Pohjavesitietojen perusteella valittiin loppusijoitustilan kaukoalueen referenssivedet liukoisuuksien arvioimiseksi TILA-99:aa varten. Kaukoalueen referenssivesien lisaksi maariteltiin myos loppusijoitustilan lahialueen referenssivedet perustuen kokeellisiin havaintoihin bentoniitin ja erityppisten pohjavesien vuorovaikutuksista. Referenssivesia tarkasteltiin myos mallintamalla (EQ3/6) erityisesti pH ja karbonaattitasapainoa seka redox-olosuhteita.

Turvallisuusanalyysin referenssivesien lisaksi on esitetty lyhyt yhteenveto erilaisia kokeellisia tutkimuksia varten kehitetyista synteettisista referenssipohjavesista, jotka soveltuvat hyvin kontrolloiduissa toistettavissa olosuhteissa kaytettavaksi. Nama referenssivedet voivat poiketa jonkin verran koostumukseltaan turvallisuusanalyysia varten maaritellyista referenssivesista johtuen kokeellisen tutkimuksen erilaisista vaatimuksista. Tallaisia synteettisia pohjavesia on kehitetty useita edustamaan eri tyyppisia pohjavesia ja ydinjatteen loppusijoituksen olosuhteita. Lyhyt yhteenveto naiden vesien koostumuksista ja valmistuksen periaatteista on myos sisallytetty tahan raporttiin.

Avainsanat: referenssivesi, pohjavesi, synteettinen pohjavesi, makea, suolainen, murtovesi, erittain suolainen vesi, lahialueen vesi, bentoniitti, redox, pH, mallinnus

1

TABLE OF CONTENTS

Abstract

Tiivistelma

Preface

1 INTRODUCTION ................................................................................................. 3

2 GENERAL ASPECTS .......................................................................................... 5

2.1 Source of data ............................................................................................ 5

2.2 Reference water-types ............................................................................... 6

2.3 Redox conditions ........................................................................................ 7

3 FAR-FIELD REFERENCE WATERS FOR THEORETICAL STUDIES .............. 10

3.1 Fresh groundwater ................................................................................... 1 0

3.2 Brackish groundwater .............................................................................. 11 3.3 Saline groundwater .................................................................................. 11 3.4 Brine water ............................................................................................... 12

3.5 Far-field reference waters ........................................................................ 12

3.5.1 Seeping calculations of some reference water parameters ........... 15

4 NEAR-FIELD REFERENCE WATERS FOR THEORETICAL STUDIES ............ 17

4.1 Near-field reference waters ...................................................................... 19

4.1.1 Seeping calculations of some reference water parameters ........... 22

5 SYNTHETIC REFERENCE WATERS FOR EXPERIMENTAL STUDIES .......... 23

5.1 Fresh reference groundwater ................................................................... 24

5.2 Saline reference groundwater .................................................................. 25

5.3 Brine reference groundwaters ................................................................... 25 5.4 Brine near-field reference water ............................................................... 26

6 SUMMARY ........................................................................................................ 27

7 REFERENCES .................................................................................................. 30

APPENDIX 1 : Some trace element concentrations in groundwater samples .............. 33

APPENDIX 2: Data on Finnish groundwater-types and the corresponding reference waters ........................................................................................................................ 36

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2

PREFACE

This study is a part of the R & D programme for the safe disposal of spent nuclear fuel in Finnish bedrock. The programme is conducted by Posiva Oy.

Note: The analysis data and viewpoints as well as some conclusions in this study are based on the available data from the four investigation sites (Olkiluoto, Romuvaara, Kivetty and Hastholmen) up to February 1998. More hydrochemical data has since been obtained and has been considered in later reports concerning the site investigations. Therefore, some conceptions presented in this report may deviate from those presented in some later reports because more insight has been gained into the geochemistry of the studied sites. This is based on the more recent data, especially at Hastholmen where the groundwater sampling in deep boreholes started late compared to the other sites.

Acknowledgements: We wish to thank Dr. M.B. Crawford and Dr. D.G. Bennett from Galson Sciences Ltd. for their review and suggestions to improve the manuscript.

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3

1 INTRODUCTION

Element behaviour in the aqueous environment greatly depends on the type of water. In addition, different parameters in the system are of importance for different elements. Often groundwaters are categorized according to major properties, e.g. salinity or the major components. In the Finnish site investigation programme, at four of the possible candidate sites for final disposal of spent nuclear fuel, a variety of groundwater-types has been encountered. In order to perform experimental studies, as well as theoretical studies, reference waters for the different groundwater-types are needed. Two categories of reference waters are discussed since the compositions between these categories may slightly differ, depending on whether theoretical studies or experimental studies are in question. The major part of this report discusses the reference waters defined for theoretical considerations and evaluations, particularly for estimating solubility limits for the safety assessment Tll..,A-99 (Vieno & Nordman 1999), and only a short summary of the reference waters for the experimental studies is given.

The first category contains the far-field and near-field reference waters for theoretical considerations. A summary of the typical groundwaters from the Finnish investigation sites is presented. The groundwater data was obtained from the four investigation sites, Olkiluoto, Kivetty, Romuvaara and Hastholmen, including all the groundwater data from the deep boreholes at the sites that was collected from samplings performed from the end of the 1980s until February 1998. The far-field reference waters are defined as based on this data and represent the conditions in the deep bedrock.

The Finnish concept for final disposal of spent nuclear fuel includes a barrier of compacted bentonite, which in a placement hole in the bedrock fills the space between the copper-iron canister and the bedrock. Bentonite is also used as a filling material mixed with crushed rock when closing the excavated tunnels in the repository. For a long time the chemistry of the near-field groundwater within the bentonite barrier is dominated by the effects of bentonite on ground water and its interaction with the copper lining of the iron canister. Thus, the near-field reference waters are defined as based on the resulting interaction of the different types of far-field reference waters with the compacted bentonite buffer. However, if the spent fuel canister is broken, other materials inside the canister, spent fuel in particular, will have an effect on the chemistry of the groundwater. Such a case has not been considered in the sense of a new type of reference water though, and only the assumed oxidizing effect on the bentonite-modified groundwater is considered.

In evaluating the processes that occur during the experimental studies it is of great importance to have good control over the studied system. In studies involving groundwater, one important factor is the composition of the groundwater. A welldefined synthetic reference groundwater can always be prepared and it also allows comparisons to be made without doubting the effects of the possible differences in the starting composition of the water that is used. Synthetic reference groundwaters for experimental studies, the second category of reference water-types, do not necessarily correspond to those chosen in the first category, because the experimental needs have additional aspects. Some of these reference waters for experimental studies have been

4

defined earlier and have already been used in some studies (e.g. U02 dissolution, Ollila 1998), but others are used in present or future studies. The definitions have taken into account the conditions in which the experiments are to be conducted, usually in atmospheric conditions or in a nitrogen-filled glove box. The atmospheric conditions have been chosen to represent the oxidizing conditions assumed to be possible in the near-field of the repository early in the evolution of the near-field and later after canister failure, as well as in the far-field in the case of the intrusion of oxidizing glacial meltwater. The nitrogen atmosphere in the glove box, on the other hand, simulates the anoxic conditions in the near or far-field of the repository. A short summary of the basics for the reference waters to be used in experimental studies is presented along with the instructions for preparation.

5

2 GENERALASPECTS

Since the late 1980s the characterization and interpretation of groundwater geochemistry has been an on-going project at several investigation sites for spent fuel disposal in Finland. Within the framework of the project, a large number of groundwater samples have been obtained at four sites giving a broad spectrum of the Finnish groundwater conditions. In this context, the chemistry of deep groundwater around the depth of 300 to 800 m is of interest.

2.1 Source of data

The hydrogeochemical sampling programme from three investigation sites, Kivetty, Romuvaara and Olkiluoto, has provided a quantity of analytical data. The hydrogeochemical data was collected between 1989 and 1997 from at least 5 deep boreholes at each of the three sites. At the fourth investigation site, Hastholmen, the sampling of deep groundwater was not started until 1997 up to February 1998 during which time sampling was performed from 3 deep boreholes. The hydrogeochemical data from Hastholmen also contains some former data gathered during the investigations performed (in 1985 and 1992) for the construction of the VU-repository for low and intermediate-level wastes.

Only the most representative data has been selected for the estimation of the reference waters (Table 2-1 ). The criteria of representativeness of the samples is based on successful field measurements, a technical evaluation of the sampling procedure (including flushing-water content), laboratory analysis, e.g. charge balance, isotope analyses, and especially the content of H-3 and C-14. The upper limit for C-14 content of the water samples is based on interpretation of the hydrogeochemical evolution of the groundwaters (Pitkanen et al. 1996a, 1996b, 1998 and Kankainen 1986). The limit is set by the geochemical isotopic dilution effect, meaning that C-14 is diluted by geochemical interaction, e.g. as a result of oxidation of organic material or calcite dissolution during a short period of time without the influence of radioactive decay. Thus, waters with C-14 values above this limit represent young, modem waters also with fairly high contents of H-3. The elevated content of H-3 in the groundwater results from the atmospheric testing of nuclear weapons between 1952 and 1969 having released large amounts of anthropogenic H-3, which has entered the water cycle and reached the groundwater. Data on the measured H-3 values in precipitation and surface waters can be found in Pitkanen et al. ( 1996b ).

6

Table 2-1. Representative data sets for groundwaters.

·· ·· Parameters I R~pt~se)ltatiye results i

·--r~~h~.i~;c~ri;~t·~·---....................................................... _ ....................................... -1.-s.~pi~;";ith. ~~·~bvious effe~ts ~{-------------··-··-·· I • leakage from multi-packer system ! • or borehole stabilization cement ___ .. ____ .... ···---·-···------·----·-·-... - ........................................................... ___ ~----.. ·--·--·---------------------·-

Amount of remaining drilling water ! < 2.5% !

·--p-if:···~i"k;ii~ii;;~··-~~idii;;······-··········································-····-·····-·······-···············-·········-T··iii~id-~~;;~;;;~~ts---·-···----·-·-------····-·--·--··---·-·-----·--·--·---·-···-·

!

--Eh···--······-----·----·-·---·········--·····-···························--·-·····················-········-·ri~~-; disturbed values accepted, and only values which

I are in agreement with the measured redox parameters I (S2

-tob Fe2+ etc.)

! ·--·---··-·------·······-········--···--·--·-······-·········-····-··-···-······················--··-r----·-···---------------------·--·---

s2- SO 2- PO 3- Nu+ NO - NO - Cl- p- I Field analysis tob 4 ' 4 ' J. .1.4 ' 2 ' 2 ' ' ' !

-~~~~-~~~: __________________ l _________________________ _ Charge Balance I < ±5 %

-·c:i4 ... [p.M]"···-·······-····· ... -···· .. ···-······ .. ···· .. ·-··········· .. ··· .. ··· .. ··········· .. ······ .. ······· ................... _. ___ i"_·<··s-o_%_ for OL *), KI*> and HH*>

-·----··················-.. ·-·········································· .. ························································································J ... ~---~~-~---~~~-~~~--------------- ------H-3 [TU] ! < detection limit for direct counting (7 -10 TU)

I *) OL=Olkiluoto, HH=Hastholmen, KI=Kivetty, RO=Romuvaara

In the early stage of groundwater sampling at the investigation sites, also some trace elements were analyzed in some of the samples, Appendix 1, Table Al-l. Additionally, some results on lanthanides (Table Al-2), as well as Th and U are also included in the data for Kivetty, Romuvaara and Olkiluoto. The groundwaters were filtered with 0.45 J..Lm Milli-pore filters at sampling. Thus the trace element contents may still include colloidal particles of smaller size.

2.2 Reference water-types

A common way to classify groundwaters is according to Total Dissolved Solids, (TDS) (Davis 1964) which gives four categories

1. fresh water TDS < 1 000 mg!L 2. brackish water 1 000 mg!L < TDS < 10 000 mg!L 3. saline water and 10 000 mg!L < TDS < 100 000 mg!L 4. brine TDS> 100 000 mg/L

At the Finnish investigation sites, three of these types of groundwater (1-3) have been observed at the planned repository depth. The highly saline groundwater with TDS at almost 70 000 mg!L has been found at a depth below 800 m at Olkiluoto. All these water-types are considered potential "far-field" reference waters for the assessment of the performance of the repository, along with the highly saline groundwater (referred to as brine in this report), even if presently there is evidence of this type of groundwater from only one sampling point (Section 5.3). The brine reference water was included since a three-dimensional volumetric model of fluid salinity variations at Olkiluoto

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7

(Heikkinen et al. 1996) has given a presupposition of the occurrence of brine-type ground water with TDS of around 100 g/L.

The near-field of the repository is expected to be dominated by the interaction between the bentonite buffer material and the contacting groundwater as long as the canister remains intact. However, in the case of canister failure, also the waste materials (the different metallic materials of the canister, the fuel assembly components and the spent fuel itself) will come into contact with the bentonite-modified groundwater, and then radiolysis in a thin water layer at the fuel surface will introduce oxidizing conditions.

2.3 Redox conditions

The use of a single Eh value to characterize redox conditions in waters is meaningless because the various redox couples in natural waters are not in equilibrium. The measurement and interpretation of the Eh measurements in groundwater investigations is also problematic. Consequently, it has been proposed to classify redox environments in terms of the presence or absence of indicative redox species, Fig. 1-1 (Appelo & Postma, 1993), and generally also based on the oxygen content of the water; oxic waters having 0 2 concentration ~ 1 o-6 M and anoxic waters < 1 o-6 M. In addition, poising (buffering) of a redox system is important.

concentration ---+ Berner 1981

ox le

post ·OXIC

-~~------)(

0 c: ea

sulfldlc

r----

methanlc

Environment

IT. Anoxic (C02 < 10"6)

A. Sulphidic (CH2S ~ 10"6)

B. Non-sulphidic (CH2S < 10"6)

Characteristic phases hematite, goethite, Mn02-

type minerals; no organic matter

pyrite, marcasite, rhodochro-site, alabandite; organic matter

1. Post-oxic glauconite and other Fe+2,

2. Methanic

C=concentration (M)

Fe+3 silicates (also sider-ite, vivianite, rhodochrosite): no sulfide minerals; minor organic matter

siderite, vivianite, rhodochro-site: earlier formed sufide minerals; organic matter

Figure 1-1. The sequence of reduction process as reflected by groundwater composition. To the right is shown Berner 's (1981) classification of redox environments together with the solids that are expected to form in each zone. (Appelo & Postma 1993).

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8

In the geochemical interpretation of the groundwater evolution at the different Finnish investigation sites (Pitkanen et al. 1996a, 1996b, 1998) the basic approach to Eh has been the above-mentioned presence or absence of indicative redox species. The redox conditions of the reference groundwaters are discussed also in accordance with this approach. In the following, the terms reducing and oxidizing are used for Eh-buffered anoxic and oxic conditions, respectively.

The base case for all groundwater-types (far-field and near-field) considers reducing conditions in the bedrock.

Reducing conditions, favourable for low radionuclide solubility and slow canister corrosion, are expected to exist at depth at all sites. The main redox reactions at depth in the groundwater are related to the anaerobic oxidation of organics, in parallel with microbially catalyzed S04 reduction, according to evidence from enriched o34S(S04), dissolved sulphides, observations of SRB (Sulphate-Reducing Bacteria) (Haveman et al. 1998) and pyrite precipitates on calcite fillings (e.g. Pitkanen et al. 1994, 1996a,b 1998a,b ). At Hastholmen the Fe2+/goethite pair is also considered important (Snellman et al. 1998). Depending on the pH, the redox level is generally expected to be buffered below -200 to -300 m V at all sites, including Hastholmen.

The potential effect of oxidizing glacial melt-water is taken into account by considering oxidizing conditions in the base case of the far-field reference water.

In the near-field, after the closure of the repository, oxidizing conditions will prevail for some time, with an estimated time scale of around 300 years (Wersin et al. 1994). After the oxidizing period, anoxic conditions are restored and expected to prevail until the spent fuel canister is broken and oxidizing conditions in a thin layer of water in contact with the spent fuel surface are induced by a.-radiolysis. Thus, also oxidizing conditions are included in the base case of the near-field.

The reducing conditions in the far-field are specified according to the proposed controlling redox-pairs and participating minerals. However, in the near-field, the redox conditions develop according to the processes anticipated to occur, e.g. radiolysis, interactions of the metallic materials and the buffers present, which may consume oxygen or related oxidants. In specifying the near-field reference water corresponding to conditions at the spent-fuel surface after the failure of the canister, only the oxidizing effect of radiolysis is considered. The oxidizing conditions in the near-field are chosen as sufficiently oxidizing to keep the important actinides in their higher and more soluble oxidation state, especially U, which is the most important one. It is anticipated that, of the actinides, Np is probably more stable as Np(IV) at a higher redox level than the other actinides of importance. Thus, the dominance of Np(V) is the presumption for the oxidizing conditions. The expected dominance of Np(V) is from a redox level of about +150 to +200 m V. However, the redox value in modelling depends on the strength of Np(IV) complexes present in the water in question and may vary according to the reference water composition. In the case of reducing conditions in the near-field, the postulated redox level is expected to be sufficiently low such that U02 or U40 9 is stable (Table 2-2).

9

Table 2-2. Summary of redox conditions in the reference cases

l·· lletltl~i~g cqnditiC)n$ j ()~i~iZ~~~ ~C>Il~iti()ns •• •• •••• .... c •.•..................... : ...... c ........................................... c ..... c ..... c ................................. :."f"···-···'~···'-'·~-··-'-···"""··"·'···'"'-·-·-·-···:.~.:.:. .. .;.~:..:c::..cc::..:..:c..:..:r-'-•~~'-'-'-'""-'-';..;•..;~~:..:.;..;....:..:..~ ....... ~:~ ...... ..:. ..

! I ····Ji;~::r.·;ld·;··· ............................................................................... T ........................................... -··········-·-····--·-··--·-·--····-·--··1-----···----·------------------·-·---·-·····

~ "Brine" ! * I

···N;·~·~=:r.;.-~1';··-···········-···-·······-····························-·······-····-l·········· .. ······-·-·······················-········-.. -·--········--·-·-·-·······-·--··r·-·-·----·--·--·-·-·-·---···--·-·-·-·-·-·-·-····-·-·---·-·-·--·-··

:::~~!~.~h±~.~-~!9.~E~~:::::::::::::::::::::::::::::::::~:::::::~:::::::J~QQ;.ZQ~9:;:::~j!~!~:~~~~~==:~~~I~fiP."iY.21~~~~~i~~~~::~~~~~~~~=~~~~~ Saline+bentonite i U02/U40 9 stable I N (V) dominant * redox defined as interpreted for the corresponding groundwaters

10

3 FAR-FIELD REFERENCE WATERS FOR THEORETICAL STUDIES

3.1 Fresh groundwater

The values given in Appendix 2, Table A2-1 are based on the QA-classified groundwater samples from the Kivetty and Romuvaara sites, altogether 12 samples from Romuvaara and 26 samples from Kivetty. At these sites, only fresh groundwater has been encountered with a median TDS value of about 140 mg!L. Specific to the groundwater in Romuvaara is the large variation in the pH values (7.7- 10.2), reflecting the effects of different mineralogical surroundings. The high pH values are seen in boreholes intersected by the metadiabase veins. The effect of the mafic rock-type is also seen in the great variations in the relative amounts of Na, (Mg) and Cl. The median alkalinity values are fairly equal for both the Kivetty and Romuvaara groundwaters. A somewhat higher level of fluoride is found in Kivetty groundwaters. Low levels of phosphate have been analyzed in the groundwater samples (associated with analytical uncertainties).

Geochemical interpretation and modelling of the ground water at Romuvaara and Kivetty indicates similar main reactions of the groundwater evolution to those obtained at the saline groundwater sites, e.g. Olkiluoto. The reactions are related to the oxidation of organics and C02 production with subsequent dissolution of calcite in shallow depths and/or dynamic flow systems, suggested by, e.g. 13C(DIC). Some oxidation of ferrous minerals is also evident. Deeper in the more stagnant flow conditions, precipitation of calcite with calculated mass transfer of some tenths of mmol/L in the fractures with an equivalent amount of silicate hydrolysis promotes evolution towards the pH level of 8 - 9. The redox reactions in the deep ground waters are related to anaerobic oxidation of organics parallel with sol- reduction, according to enriched 34S(SOi), minor dissolved sulphide and pyrite precipitates on calcite fillings (Pitkanen & Snellman 1997).

The fresh reference water chosen is the simulated granitic ground water (A !lard), which contains about the same amount of dissolved salts (TDS) as the groundwaters from Romuvaara and Kivetty. Allard water (Allard et al. 1981) actually represents the most evolved groundwaters from these two sites in respect of TDS, chloride content, and the main cations. The compositions for the basic Allard water and Allard water in oxic and anoxic conditions are given in Appendix 2, Table A2-1. The basic Allard water has been modified to meet the equilibrium requirements for oxic conditions at log Pco2 of -3.5 representing equilibrium with air, and for anoxic conditions at log Pco2 of -4.0 representing nitrogen atmosphere in a glove box. These equilibrium conditions are met when calcite and quartz or Mg-silicate phases are saturated.

The redox conditions for the anoxic water representing reducing conditions are defined by the sulphide/sulphate equilibrium at a maximum sulphide content of 3 mg!L.

The corresponding redox conditions for the oxidizing conditions are defined as being oxidizing enough to keep Np at its higher oxidation state (Np(V)).

11

3.2 Brackish groundwater

Brackish groundwaters with TDS ranging from 2 000 - 9 800 mg!L have been observed at Olkiluoto and Hastholmen. At Olkiluoto, brackish Na-Cl or Na-Ca-Cl-type groundwaters occur from a depth of 60 m to a depth of 400 - 500 m. At Hastholmen, brackish-type ground water has been obtained from a depth of about 100 m to a depth of about 600 m. Altogether 22 representative samples were considered from Olkiluoto, and 5 samples from Hastholmen, Appendix 2 (Table A2-2).

At Olkiluoto, two end-member waters of brackish-type have been identified. A brackish HC03-rich water occurs at depths down to 100- 150 m and a S04-rich Litorina-type water occurs at depths of 100 - 300 m. At Hastholmen, the imprint of Litorina is even stronger, and the strongest influence is seen at depths of about 100-400 m. The Litorina-type groundwater has very high contents of sulphate and magnesium. Typically, also ammonium, iron and manganese show peak values in the Litorina-type ground waters.

At Olkiluoto, the reducing conditions are strongly buffered by the microbially mediated anaerobic oxidation of organic carbon (methane) and reduction of sulphate as a consequence of which pyrite precipitates if Fe(m is present. The evolution of pH is buffered by the carbonate system and later also by silicate hydrolysis at Olkiluoto. The lack of solubility constraint for iron keeps iron at a higher level at Hastholmen and the iron hydroxide complexes formed keep pH at a lower level. The redox conditions at Hastholmen are probably limited by the Fe(m/goethite and S2-totfSOl-/pyrite equilibrium. The observations are in accordance with the frequent observations of iron hydroxide on the fracture surfaces and occurrence of IRB (Iron-Reducing Bacteria) (Haveman et al. 1998). There are observations of dissolved sulphide in the brackish and saline groundwater at Hastholmen, but the sulphate values in the deep groundwater are still at a rather high level. Apparently, sulphate reduction is constrained by the lack of a suitable electron donor for the SRB to use, i.e. the type of dissolved organics, which, on the other hand, may be more efficiently used by the IRB competing with the SRB for the organic substrates. The iron/goethite system probably leaves the redox at a somewhat higher level at Hastholmen compared to Olkiluoto, where the strong sulphate-tosulphide reduction, especially observed at depths from 400 - 500 m, buffers the Eh to quite low values.

The brackish reference water chosen is the most strongly Litorina-type groundwater found in boreholes HH-KR 1 to HH-KR3 from Hastholmen, being represented by borehole HH-KR3 from the depth of 336-339 m (Appendix 2, Table A2-2). This water represents a groundwater-type that has a very strong influence on the present day brackish groundwater conditions at both Hastholmen and Olkiluoto.

3.3 Saline groundwater

Saline Na-Ca-Cl-type water occurs at Olkiluoto at depths below 400 m. At Hastholmen, saline groundwaters have been found below 600 m. Altogether 11 saline groundwaters

12

from Olkiluoto and 4 saline groundwaters from Hastholmen have been included in the considerations.

More saline groundwaters (higher TDS content) have been found at Olkiluoto compared to Hastholmen, although the median TDS contents are fairly equal. Sulphate is at the detection limit at Olkiluoto compared to the fairly high level at Hastholmen. Due to the reasons discussed above, also the redox determining reactions are probably slightly different at Hastholmen. The strong input of methane, which has been observed at Olkiluoto, is lacking at Hastholmen; also a higher input of dissolved hydrogen gas is found at Olkiluoto. The lack of sulphate, strong input of methane and hydrogen seems to buffer the redox to a lower level at Olkiluoto compared to Hastholmen. The redox conditions at Hastholmen might be more dominated by the balance between iron minerals and groundwater, although signs of both methane and sulphide are observable. Correlated to the redox conditions, the pH level is also somewhat lower at Hastholmen.

The groundwater sample OL-KR1 from the depth of 613-618 m at Olkiluoto (Vuorinen et al. 1997) was chosen as the saline reference water, Appendix 2 (Table A2-3). This water represents fairly well the mean composition of the saline water at Olkiluoto and corresponds to the most saline groundwater observed at Hastholmen The groundwater at 613 - 618 m has been sampled on several occasions since 1990 and remained similar during the samplings. The water is interpreted to be chemically fairly stable (Pitkanen et al. 1994, 1996a). The content of bicarbonate (alkalinity) and sulphate is fairly low. The Eh of the water is proposed to be buffered by sulphate reduction due to the use of methane as a source in the microbially catalyzed reduction process.

3.4 Brine water

Groundwater with high salinity approaching brine-classified groundwaters (TDS > 100 g!L) has been obtained at Olkiluoto. The electrical conductivity measured in groundwater samples taken from three open boreholes with a tube sampler in 1996 hinted at TDS values with a maximum of about 70 giL (Ruotsalainen & AlhonmakiAalonen, 1996). This was obtained from a depth of about 1 000 m. The groundwater sample from the depth of 861 - 866 m from borehole OL-KR4 sampled in 1997 has a TDS of 70 giL (Appendix 2, Table A2-4). As pointed out in Section 2.2, the term brine was chosen to be used here for this water because groundwater with even higher TDS, about 100 g/L, has been postulated to occur at Olkiluoto.

3.5 Far-field reference waters

The far-field reference waters are summarized in Table 3-1, and as pointed out earlier, reducing conditions are considered for all far-field reference waters, and only for the fresh reference water (modified Allard) are oxic conditions also taken into account The reducing conditions are determined by:

sulphide/sulphate/pyrite equilibrium in the fresh water (Allard) Fe(II)/goethite and sulphide/sulphate/pyrite equilibrium in the brackish reference water (HH-KR3),

---------------------------- ~----

13

sulphide/sulphate/pyrite equilibrium in the saline reference water (OL-KRl), sulphide/sulphate/pyrite equilibrium in the brine reference water (OL-KR4).

The basic modified composition of the fresh reference water Allard is updated by adding some anions and cations; the added amount of anions F, and PO/-, are the maximum concentrations found in the Kivetty and Romuvaara groundwaters, also the maximum amounts of cations AI, Mn, Ba, Sr, Cs and NIL observed for the Kivetty and Romuvaara groundwaters are added. In reducing conditions either mainly Fe as Fe2

+ or S2- is added

to the water.

The oxic conditions for the fresh reference water (modified Allard) are stated to be oxidizing enough for Np to remain at the higher oxidation state, Np(V).

14

Table 3-1. Far-field reference waters. (OL-SR referring to the saline reference water for experimental studies, see Chapter 5)

ALLARD IALLARD- ALLARD- BRACKISH-,SALINE- SALINE- BRINE- ..

-·-·-·--·--·-···-···· ···-·-·----~------ ·--·-·-·-·OX -·-- ·- RE_ RE RE .. RE -~ Basic I logpcoz i logpcoz HH-KR3 j OL-KRI OL-SR OL-KR4

! =-4 i =-3.5 ! Depth ·•·•·.. . .. · •. ·•. _lP, __ ··-···--·· ......................................... L ......................................... J.. ............................ -··············t········-·-··-·-?.}_~----·-····-·.J.--~-~:?. ........ L. ___ §_!}_ ......... ···-··-·-···-~-~!.. .............. . ~t~~;~~~---·--·· ·-·--·-·-·-···-·······-···········t···-······<:3oo······-·+-·····-·---··---·---·--t--·--:~~-----·f_2Z9 I -25~---··- -·-- -

3*) ---

TDS " 220 I 185 ! I 9778 I 24000 20000 I 70000 *) uncertain values due to analytical problems.

**) these parameters are affected by the redox buffers acting in the system.

15

3.5.1 Seeping calculations of some reference water parameters

In general, solubility equilibria provide upper limits to the concentrations of dissolved trace metals. Modelling (EQ3/6, W olery 1992) was used to obtain solubility equilibria for a few trace metals (Ba, Sr) and changes in some important parameter values (carbonate/pH and redox) in the far-field reference waters. The database used was Data0.com.R2 (generated by GEMBOCHS.V2-JEWEL.SRC.R3 02-Aug-1995) maintained by Lawrence Livermore National Laboratory. The database includes a melange of data, measured values as well as estimates based on correlations and extrapolations, the objective having been to compile a database able to solve models of complex systems. Thus, the database by its nature offers less assurance of internal consistency.

The solubility of barite (BaS04) was used to constrain barium content, as it is a likely control for barium in natural water (Hem 1989). For strontium it has been stated (Hem 1989) that its concentration in natural waters does not approach the solubility limit of either celestite (SrS04) or strontianite (SrC03), but experiences from the Finnish groundwater samples have shown that strontianite may be over-saturated in our groundwater as well as calcite (CaC03). The calculated over-saturation may be an artefact due to problems of sampling deep groundwater (out-gassing, contamination, uncertainty in the analytical data, etc.) but it may also be true, and attributed to, e.g. kinetic effects. However, celestite and strontianite have not been reported from fracture mineral studies, and therefore it is rather more probable that the strontium concentration may be controlled by eo-precipitation with calcite, which is a very common fracture mineral at all sites at the proposed depth.

The carbonate/pH system as well as the redox system are quite essential in determining solubilities, and therefore it was felt important to have some estimation of the changes that occur in these systems, especially as the pH range to consider in the reference waters was quite large, from about 7 to about 10. At low pH there is no problem of high oversaturation of carbonate phases, but at high pH equilibrium with calcite and strontianite was presumed. (Note: The high pH may be due to other systems than carbonate, e.g. silicates, but here only the carbonate system was considered.) The redox constraints in the reference waters are discussed in some detail below. The calculated values for the parameters in the reference waters are given in Table 3-2.

In the reducing Allard-water (ALLARD-RE) the pH range considered was taken according to the range of the measured fresh groundwater pHs, from 7 to 10.5. The redox was assumed to be constrained by the sulphate/sulphide/pyrite system, which kept the iron content at a low level of about 10-13 M in all the considered cases. With this choice of constraints, the maximum concentration of sulphide (3 mg!L) was seen only at the highest pH considered (10.5).

16

Table 3-2. Some calculated (EQ3/6) parameter values (25 CC) for far-field reference waters in the considered pH ranges.

·~ifEREN.CE !.• pHf Eh llogf Ctot•IHCo3-jcol-.J.tjatOt .. • F~tot·····•···.· us-/ soi-L JJ1ltot· · >Srtot ·-··-·w-ifiii····~T .................. r-~v-... TP~~;·r~·--r--.. -~--·-r-;M·-·r~- ·-·---M·----M ~.;M--1-io-s"M-- 1o:5i1 ... ALLARD-RE I 6.9 I -205 l-2.21 1.17 I 0.23 I - I 0.13 - 10"13 7.4·10"5 0.079H.24 I 0.22 ..... -·---·-----------·------.......................................................................................................................................................................... -r·-·-----·- -·-----· -·----.. -; ~-·----· ·----t-.. ·---·--.......... .. I- o.oo5 M 1 8.o 1 -278 l-3.21 1.11 I 1.13 I o.o1 1 o.13 -1o-13 1.3·10- o.o75 o.24 j 0.22 .................................................. . ........................... , ...................... ; ............................ ! ................................ + ........................... !............................ ......... .. .............. ----·-; ............................ ---·----·-··-·-·-................................... .

I 8.9 1 -339 ! -4.11 1.16 1 t.o8 1 o.o1 1 0.12 - 10-13 1.1·10- o.o8o o.23 o.o8 ------·-·-.. -·-.. -·----r~o~·s-l=449 ... l~6~TrT:os .. l ..... o~36To:691M2r -1o-ll 9.0·10_, o.o97·1 o.23 1 -om-·-

~=@l~&11hE~~-*td-=-1 9.0 1 -343 !-6.0! o.o4 1 0.02 1 0.002115.35 0.4·10_, - 4.3

1 - 1 -

In the reducing brackish reference water (BRACKISH-RE), the range of pH considered was from about 7 to 9. At Hastholmen the goethite/iron system was used as a constraint. In the reducing saline reference water (SALINE-RE), the range of pH considered was also from 7 to about 9. Similar processes as in the Allard water govern the redox conditions in the saline water. Additionally, methane has been encountered in saline groundwater implying somewhat lower redox conditions than brought about by the sulphate/sulphide/pyrite system, which was used in the calculations.

In modelling, the results at high pH indicate lower alkalinities compared to some analyzed data for the high-pH groundwaters (alkalinities of about 1.6- 2.0 meq/1) and thus also somewhat higher carbonate contents were considered when evaluating the solubilities (Vuorinen et al 1998).

Oxidizing conditions for the fresh reference water (FRESH-OX) were also estimated by modelling. Having conditions in which the log Po2 value was -10 were enough to keep Np at its higher oxidation state (V). The strongest Np(IV) species at low pH was phosphate, which required the high redox conditions. Table 3-3 gives the modelcalculated redox values for the four pHs at log p02 of -10 and -30.

Table 3-3. Model-calculated redox values in oxidizing conditions.

=:::ifE=i:ili±=~ 7 ! 667 ! 373

:::::::·::::::::::::::::::~::::::::::::::::::::::::::t:::::::::::::::~Q:~:~:::::::::::J::::::::~::::~:~:~::::j:ii:~~::=~~:~~ ......................... ?. ........................ ...l ................. ?..~ ................ L ................. ...1?l _____ _

10 I 489 I 194

17

4 NEAR-FIELD REFERENCE WATERS FOR THEORETICAL STUDIES

In Finland the considered reference backfill material in the disposal vault of spent nuclear fuel is commercial sodium-saturated MX-80 bentonite whose composition is given in Table 4-1. Due to the chemically inhomogeneous nature of the material, the table gives ranges for the components and indicates only the major mineral phases. The non-mineral components (organic matter excluded) given in the table represent the minor mineral components of bentonite, which have not been analyzed, but are assumed to occur at least partly as known mineral phases; sulphate as gypsum (CaS04), sulphide as pyrite (FeS2), carbonate as calcite (CaC03), fluoride as fluorite (CaF2), and phosphate as hydroxyapatite (Ca5(P04) 30H). The presence of pyrite (0-0.3%) in MX-80 has been reported by Mi.iller-Vonmoos & Kahr (1983).

Table 4-1. Composition of MX-80 bentonite (Lehikoinen et al. 1996, Muurinen et al. 1996).

CoiJ~pouent I % by,Y~ig~~ ·····M~-~t~~;iii~~-ii~····--·-·-··-·-·-··· .. ·········-·····t·~6s·=·s-o--~~~-~---···-···~·-·-

=~~=-=-~ .::::~~:!~~1?.:~::::::::::::::::::::::::~::::::::::::::::::::::::::::::::::::~:~::::::::::::::::[~~~;~::~:~::~~~~~::~~::~:~::~:::~~~::~~:

Kaolinite I <1-1.7 ·····c:;b~-~~t~·····················································-···········-·-·-·r··i4~2·--·-·-·-········-·-·--·--·-·-·-····-·

:::::§:~)lih~!.~::::~::::::::::~::::~::::::::::~:~::::~::::::::~:~:::::~:~::::~:::::::I~9.::~~:~9.;~~~::~=~:~:~~:::~~~:~~:~=: ..... ~~~-~P.~.~!~ .......................................................................... J .... .9: .. ! .............................................................. -·-Fluoride I 0.1

·········-·················································--··············-·············-···········-···········-·+·-·-·-··-····-·-·--·--··---·--·-·-·--·--·--·-·--

if:===~ Ni ! <0.01

·····a~·····~~i~---~~tt~~······································-················r·a~-3-~<i4-·-·········-··-·-·············-·-····--·

In the near-field of the spent-fuel canister, bentonite is expected to bring about changes to the chemistry of the groundwater equilibrated with it. The chemical changes brought about greatly depend on the type of groundwater; fresh, brackish, saline or brine, but also the time of equilibration is an important factor in the resulting composition of the near-field water. The composition of the near-field water is assumed to be bracketed in the range from the bentonite-affected groundwater in the short-term to that of the contacting groundwater in the long-term. It is assumed that a very long equilibration time will allow completion of the expected dissolution, precipitation, sorption, diffusion and ion- exchange processes.

The compositional changes occurring in groundwater in contact with bentonite have been studied in recent laboratory tests (Muurinen 1997, Muurinen et al. 1997) using different groundwater-types (basic Allard-water, Saline reference water (OL-SR), and Brine water in Table 3-1). The observed chemical changes in the waters are summarized in Table 4-2, which gives information about the changes to be expected in the shortterm. The tests with Allard water (308 d) and saline water were performed in closed

18

systems in a glove box with N2 atmosphere and low C02 content, whereas the test with brine ( 14 d) was performed in a closed system in the laboratory environment.

Table 4-2. Changes brought about in the different groundwater-types by contact with bentonite. The contents in initial waters and contents obtained after contact with bentonite are shown. Note! The values in the table have been rounded

S~Iia1~ gw Brine initiai I blilatnef1 irutiru obtained ihltiw I obtained

n.a. not analyzed

Some conclusions based on the data from Table 4-2;

The extent of bentonite interaction is strongly influenced by the ionic strength of the contacting groundwater and consequently the greatest effects are seen in the fresh groundwater:

• The obtained alkalinity is four-fold compared to the initial one, and the pH value is about half a unit lower.

• Sulphate concentration increases by roughly two orders of magnitude (in mmol/L) as well as does sodium.

• Concentrations (in mmol/L) of the other constituents increase about one order of magnitude.

• Consequently the ionic strength (and TDS) is also increased. These changes are consequences of the dissolution of the easily dissolving mineral components of bentonite, i.e. calcite and gypsum, and possibly pyrite if oxygen is present in the system (Note: However, without bacterial mediation pyrite dissolution is very slow). Some ion exchange of Ca2+ to Na+ also occurs. The reason for the decreased pH value in the case of Allard water is not clear.

Brine with a high content of calcium indicates the probable restriction of dissolution of the ea-containing minerals (calcite and gypsum) of bentonite and thus the sulphate concentration and alkalinity reached are at much lower levels than in the case of fresh ground water.

The effects of bentonite on the saline groundwater seem to fall somewhere between the two extreme groundwater-types and the effects on brackish groundwater are expected to settle down between those of the fresh and saline groundwater-types.

19

Ca/Na ratio compared to the initial ratio in groundwater. The change in the Ca/Na ratio (in equiv.IL) is smallest in the case of brine, a drop to about a quarter instead of a drop to about a ninth or a sixth, as in Allard water and saline groundwater, respectively. There may be several reasons for this, which have not been evaluated; possibly the exhaustion of the ion-exchange capacity of bentonite, limited dissolution of bentonite minerals connected with consequent ion exchange, perhaps the shorter interaction time, sorption, etc.

In bentonite water, ions that are not involved in the ion-exchange, dissolution or sorption processes have about 20 % higher concentrations (e.g. Bf) compared to those in the interacting groundwater. This has been attributed to the exclusion effects of ions, on which more detailed information is found in Muurinen (1997), Muurinen & Lehikoinen (1999) and Lehikoinen (1999).

4.1 Near-field reference waters

The laboratory results are presumed to represent a situation in the buffer material before equilibrium via diffusion is attained with the interacting groundwater body. It is also assumed that bentonite has maintained its physical integrity so that its hydraulic properties, pore structure and diffusion characteristics have been kept unchanged. On these bases, the following near-field reference water compositions are proposed.

Considered water-types: As noted above, the changes brought about seem to be bracketed with the two types of near-field waters, bentonite interacted with fresh groundwater and brine. The most frequently found groundwater-types in Finland in this context are fresh, brackish and saline. On the assumption of the bracketing effect, two near-field waters are chosen; FRESH-NEAR and SALINE-NEAR, although in the assessment of radionuclide solubilities some consideration should also be given to BRINE-NEAR in order to ensure that no dramatic changes are expected in that case.

pH: Calcite (roughly 1 weight-% as C03) in the bentonite clay will contribute to the pH buffering capacity. Also other soluble salts present in bentonite or added by groundwater, as well as montmorillonite, the most important mineral in bentonite, will influence the pH of the porewater. The pH of the buffered bentonite porewater is anticipated to be in the range of 7 - 9 (Pedersen & Karlsson 1995). Thus, no big changes to the original pH of the interacting groundwater are expected. This is also seen in the case of saline or brine-type ground water (Table 6-1 ). The reason for the decreased pH in the interaction experiments with fresh groundwater and bentonite is not clear. The span of the pH values in the near-field reference waters will be taken from the span of the reference groundwaters.

Redox conditions: As pointed out above, both oxidizing and reducing conditions in the near-field need to be considered.

1. Reducing conditions in the near-field reference waters (FRESH-NEAR-RE and SALINE-NEAR-RE) are determined accordingly, with the reducing groundwater, but at least to a level allowing stability of the U02 and U409 phases.

20

2. Oxidizing conditions in the near-field reference waters (FRESH-NEAR-OX and SALINE-NEAR-OX) are due to radiolysis, which brings oxygen and other radiolysis products into the water causing more aggressive corrosion of the metallic materials in the repository. The oxidizing conditions are considered oxidizing enough to keep Np at the higher (V) oxidation state.

In groundwater, microbial processes are known to reduce sulphate to sulphide. This is not expected to occur in the near-field waters. Recent microbial studies have indicated that the pore throats in bentonite (compacted to 1.22 Mg/m3

) are too small (average < 0.05 J.Lm) for bacteria (general diameters from 0.1 to 1.0 J.Lm) to move about and reproduce effectively (Stroes-Gascoyne & West 1994), and that the water activity is low enough, in the beginning about 0.75, to exclude the majority of micro-organisms. Therefore, keeping the water activity low, at for instance 0.92 (water content 20%) will limit bacterial processes (Pedersen & Karlsson 1995). Thus, anaerobic microbial processes are not expected to occur in the buffer material and the reduction of sulphate is not expected to take place. This will leave the high concentration of sulphate in the near-field water, especially when interacting with fresh groundwater. However, sulphide is assumed to be present in the reducing near-field water at concentrations of about 20 % higher (exclusion, further information on exclusion phenomena in bentonite can be found in Muurinen & Lehikoinen 1999 and Lehikoinen 1999.) than in the initially interacting groundwater.

Content of other species: Those anionic species, which have not been studied in laboratory tests, are included in the reference ground waters with the concentration of the corresponding reference far-field ground water but taken at a higher (about 20%) concentration brought about by the expected exclusion. Cationic species other than Ca2+, e.g. NH4+, Sr+. Ba2+, etc., may also undergo ion exchange, but because of the lack of knowledge about their behaviour and preferences in the system they will also be given a somewhat (20 %) higher concentration than in the contacting groundwater. It has to be noted that the concentrations proposed for the near-field reference waters given in Table 4-3 are not at this stage based on realistic concentrations in the sense that, for example, precipitation of sparingly soluble phases, e.g. SrS04 and BaS04, has not been considered as to restrict the concentrations of Sr and Ba. This kind of discussion will be presented in the context of assessing the solubilities of the various elements (Vuorinen et al. 1998) for performance assessment.

In the near-field reference waters, in addition to hydrolysis, ion patnng and complexation with sulphate will be induced by the high concentration of sulphate and the high alkalinity will induce carbonate complexation.

In the case of oxidizing conditions, the content of iron in solution is expected to stay at very low levels except perhaps at the proposed lowest pH value ( = 7 .0). In natural oxidizing waters, iron concentrations are often controlled first by Fe(OH)3 because attainment of crystallinity with the more stable and less soluble phases (e.g. hematite and goethite) may be very slow (Hem 1989). In reducing conditions, the low solubility of iron sulphides (e.g. pyrite) will probably prevent the simultaneous presence of "high"

21

attainment of crystallinity with the more stable and less soluble phases (e.g. hematite and goethite) may be very slow (Hem 1989). In reducing conditions, the low solubility of iron sulphides (e.g. pyrite) will probably prevent the simultaneous presence of "high" contents iron and sulphide. Iron oxyhydroxides are also well-known scavengers for trace elements, to the extent that the concentration of a trace element is brought down to almost nothing in solution.

Table 4-3. Proposed composition for the two near-field reference waters. (Fe, Cu and U are not included as their concentrations are discussed in the context of corrosion of the spent-fuel canister (Vuorinen et al. 1998) and the solubility of U (Ollila & Ahonen 1998)).

FRESH- FRESH- SALINE-·. J ... ·••·•SAI.IN~t····· NEAR-OX NEARO.RE NEAJlO.OX ··I• NEAR-RE ..

.... ~h:£~.~~.!?-~.: ....................... 1. ................................................... }:~P(Y.) ..................... J.. ............. ~Qi.~tQ~ ...................... -..... ...!iP.lY.1 ............... J ............ !!.Qi.~1Q~ ............ .

. _.P..!!.. .... _ ... __ ....................... L .................................................................................. ?..:.9.~J.9.:Q .......... ___ ........... _ .. __ .......... ·---·---------1 .o-9 .<?_ ___________ _

.... ~l..~li~----·--1...!!!.~9.~ ..................... -...... -................................. J..:Q __ ,.,._, ____ ,,_ .. ,_. __ f-- 1.4 Ionic strength i M -0.3 -1.1 ..... -----·----·-----·-.. ·----·-··"•-.................................................................................................. -......... -................... -... -.... -·--·-·-· -·---·-------·--------·------TDS ·. i mg!L -15 000 -35 000 ·-· . -·. -~· . __ ..,... .. _,.;.,._;. ................................................................................................................................................................................................. - .......... -................. _ ..... , ..... _ ... , .................................................. . SiOl . I - " - 23 10

::]~=:=~~~=~~:~~~::~:~:~:[~:::::::::~:~:::: ::::~:~~:::~::::~::~~:~:~:::::::::~:::::~:~:I4oQ:~~~:~:~~~~::=:~~~~=:=. ~:-·---------i-2-ooo--~==~~ K i -"- 50 90 ..... c·;-.................................................... r .. ·=-.. ·;; ..... = .................................................................... i9o ............................... -.... -·-·-·-·-·- .. _____ .. ________ .. ___ ! 6oo ----·---·----·

:::::~i~~=:~~::~~:::~:::~::::~::::::::::]:::~::::~~::::~~::::::: :::::~:::::::~:::~::::::::::::::::::::::~:::::::~::::::~~=:~:~:~::~::::::~::~=:~:~~:~=~:~ :~:~~~~:~=~~=~:=:~=~~]l<i~=~~=~~:=:~=~ AI ! - " - 0.8 0.2 -·-Mn----·--.. ·-··--·-.. -·-.. r .. = .. ·-,; .............................................................................. o~? ................................. ______ 2.6 ----

=i; ................. :~~~=~~]:::::~::::~~::::~::::::: :::::::::::::::~:~::::::::::::::::::::::::::::::::::::::~:9.~:~::~:::::::~::::::::::::::~::~:~:~:~:~:::::~::~:~:: ::~::~:~:~:~~=~~:~~~:~~:~:=}]~=:~=~:~~=~~~~=~:~~~~ Sr I - " - 0.3 67

:::::~~~::~=:=~~~==::::~:~:::::::~r::~:~:~::::~::::::: :::::::::::::::::~::~::~:::::::::::::::~::::~::~:~9i:91~~::~:~::::~::::::::~:::::~~:==~= .. -·---·-·-.. ·---·-·-----~~---~~===---=

:::::~~~:::::::~::~:~:~:~:~~::::::~:~::::::1:::~::::~~:::::~::::::: ::::::::::::::::::::::::::::::~::::::::::::::::::::::::::::::r::::::::::::::::::::~:::q;.:?.:::~:~:=:~:::::~:: :::~~=~~~-----~:~~:=~=r:===~:??: .. ~~===-~ Cl l - " 420 17 000

....................................................................... · ................................... ···························-····················-··········-·-···················-············· ... ··---··--·--·-·· ----.. ·-·---.. ·-··---.. --------·-·-··--F " 6.2 3.5 ..... _ ................ - ............... _ ............................................................... _, ............................. -------.. -·--·------

..... !!! ....... -........................................................... ~~ .............................................................................. ~ .. :.9. ........................ _ .... _, __________ .. .. .... ·----·---·--·--·-·-·--·!~9--·----·-·-·-·-·-·------1 I - " - o.s 2.3 Po~---. ·• .-. -~,.....r·= .... ;; ..... = ............................................................... ij .... *.) ......................................... _ ............................ -.................................... o:·2-*5·--·--................ -.......... --.. ·-·

:::~~!~9!!!~:=~~:~::~::::::::::::::[~:::~:::::~::::::: I 4. o I 4. o so.. ! - 9 400 3 200

*) Uncertain values due to analytical problems

As a result of a-radiolysis, mainly H2, H202 and 02, are produced in a thin water layer on the surface of the spent fuel. Gaseous H2 is thermodynamically not very reactive at temperatures < 1 00°C, and is thus expected to be transported by diffusion out of the near-field, whereas the strong oxidants 02 and H202 are anticipated to react with the spent fuel and metallic materials (cladding, structural parts, container materials). High amounts of hydrogen gas are anticipated to form due to corrosion of the iron container, which is one main consumer of the oxidants formed after canister failure.

Oxygen and sulphide ions are the only components in the groundwater that will corrode copper (cf. Section 5.1 in Vuorinen et al.1998). Copper oxides are produced in reaction with oxygen, copper sulphides and hydrogen in reaction with sulphides. Hydrogen could, in principle, act as an electron donor in bacterially mediated sulphate reduction

22

S042- + 4H2 :::::} HS- + OH-+ 3H20 .

The produced sulphide could then react with copper ions and lower the free energy of the reaction enough for copper metal to become oxidized spontaneously by hydrogen ions in water

2Cu + HS- + H20 :::::} Cu2S + H2 + OH- .

This type of corrosion of copper is limited by the low concentration of sulphide in the groundwater unless microbes can reduce sulphate (Pedersen & Karlsson 1995). However, as noted above, microbial activity in the bentonite buffer is not presumed to occur to any great extent.

The corrosion of copper and iron is not expected to elevate the concentrations of their aqueous species significantly. The possible corrosion processes of Cu and Fe under repository conditions and the solubility of copper and iron in the reference conditions are presented in the context of assessing the solubilities of the various elements (Vuorinen et al. 1998) for performance assessment.

4.1.1 Scoping calculations of some reference water parameters

Some minor scoping calculations (EQ3/6) were also performed for the near-field waters. The redox in reducing conditions was modelled by constraining the oxygen fugacity with magnetite/hematite or magnetite/goethite. In oxidizing conditions, the same logp0 2 values were assumed as for the far-field oxidizing conditions. The computed results are given in Table 4-4.

Table 4-4. Computed (EQ3/6) Eh values for the near-field at different pH values.

L magll~t.it~lhematite.•·!·· .. •D1ag)letite/go··· ~.th···-it_.~J_I ~o·g····· f1_·~_2_._._=_•·.•.•.·.•_,._•_I_._o_._._ •• _ ••.• _ •.•• _._••.·.••.i• logp(J/7~30 ll J· Eh mV ···· >l Eh mV •····•·•·-• i .. EhmVJ . Eh .. m

........ ,.c: .. ?. .. ~ ............ t ......................................... :.~.?..4. ....................................... ..J ..................................... ::.!.§..~ .................................... J ....................... -.... ~§Z.._ ... , ........... -.. ·--1-·-···--···--.ll?.. .... _ ............. -........... . 8 ~ -313 i -228 ! 608 I 312

············m9 ..... mm··I::::::::::::::::~:::::::::::::::::::::~:~:z~.:~:::::::::::::::::::::::::::::::::::::[::::~::::::::::::::::::::::::::::~~-~:~:?:~:::::::::::~::::::::::::::::::~:I:~:~:~:~::~:::::~~~l~§.~~~:~~:~:~~=~~~==~~~:~::~~~~J.i~:~~=~~~~~~~-· 10 i -413 i -346 i 489 i 194

For the near-field reference waters, also some estimations of the pH and calcite system were computed. The fresh near-field reference water has quite a high alkalinity, which at high pH results in a high over-saturation of calcite, whereas in the saline reference water the same effect is brought about by the high Ca content. The computed results when calcite equilibrium is required at different pH values in the systems are given in Table 4-5.

Table 4-5. Computed (EQ3/6) results for the fresh and saline near-field reference waters when calcite equilibrium is required

Fresh near-field ............... L .......... ··· .. -...... .Saline near--field ··'"'····::n··· .. l····'··-···c;:····-····:·M·-·········]···············-·······c;········,·-··"i\r··-····-·-·······-····r·····:···-·-·~:-·u--,-·T-rT·-·rCR~rM"rs~rrcc;sr~~i\1~7··----·

7.3 I 7.44E-03 I 4.74E-03 ! 7.1 I 1.39E-03 I 3.99E-02 ····························i-······························-································~······-································-········································· .. ····-···+···················-·--················-·-···~···-··--··· .. ----.. ·---.. · .. -· .. -·--· .. ·-1·---·-... -.... ,, __ ................... _ ...... _ ... , ... __ _

8.1 I 4.11E-03 I 1.42E-03 I 8.0 ! 4.11E-03 I 3.87E-02

::~:::2:;:9.::::::::c:~::::::~~2:~~~q~:::::::::~:::r::::~::::::::::::::::::::~~~I~~q4.::::::~:::::::::::::~::I:::::~:~:~:~~:;.!~:~:::::::::::II~~~~~~-~~~~~~~~~]~]]~~~9.~~-~~~~:~~~~:~~~~~~:~~: 10.0 j 2.76E-03 I 6.08E-05 I I I

23

5 SYNTHETIC REFERENCE WATERS FOR EXPERIMENTAL STUDIES

In the Finnish investigation programme for safe disposal of nuclear waste, various experimental studies mainly on sorption, diffusion, solubility and dissolution mechanisms are performed in laboratory conditions. In the disposal concept, both oxidizing and reducing conditions are taken into account and thus these conditions are simulated in the experimental studies. Usually the oxidizing condition is the ambient laboratory atmosphere and anoxic nitrogen atmosphere in a glove box represents the reducing conditions - but the conditions are really reducing only when reducing agents are present in the studied system, otherwise the conditions are only anoxic. Thus, in the following we deal with oxic and anoxic reference waters.

In the glove box the C02(g) content of the nitrogen atmosphere is very low, about 0.1 ppm and the 0 2(g) content below 1 ppm. In long-term tests, if the water used is not close to equilibrium with the atmosphere, some changes in the pH and carbonate system occur. Therefore baseline reference waters of different types with a well-known starting compositions have been defined for both oxic and anoxic conditions. In some experiments in the anoxic conditions poising with redox species is also used which may have an effect on the originally defined pH of the water (especially S2-), which is not adjusted to the baseline value but allowed to settle by itself.

Baseline far-field reference waters so far considered in the experimental studies are fresh, saline and the highly saline (called brine) waters. The near-field reference waters considered are the fresh-bentonite and brine-bentonite waters.

The procedure for determining the compositions of the reference waters, after choosing the composition for the baseline water, based on the analyzed groundwater data, was the following:

• the composition was first evaluated by modelling (EQ3/6, Data.com.R2 and DataO.hmw.R2 generated by GEMBOCHS.V2-JEWEL.SRC.R3 02-Aug-1995, W olery 1992), in order to find a satisfactory equilibrium content (open system),

• then appropriate chemicals were chosen and the water was prepared. • In some cases the stability of such water was evaluated for some period of time

by measuring the pH and analyzing the contents. The waters to be used in ambient laboratory atmosphere were computed to be in equilibrium with the atmospheric log Pco2 = -3.5 and those to be used in the glove box were computed to meet equilibrium at log Pco2= -4.0 or -7 .0. In the modelling, these assumptions usually indicated an over saturation of calcite as well as some other phases, e.g. dolomite, some silicate and phosphate phases. A satisfactory content of the reference water was usually obtained by requiring equilibrium with calcite and some silicate phase (e.g. talc) and in the case of phosphate, with apatite phase (e.g. hydroxyapatite).

The practice in preparing the simulated waters is to first make separate stock solutions of higher concentration from which the required amounts of solutions are then added to the prepared water. The last two solutions to add before the final adjustment of pH (if necessary) are the silicate and bicarbonate solutions, but preferably bicarbonate is added in solid form. Note: For silicate and bicarbonate, only fresh solution should be used. The pH of the silicate stock solution is neutralized to about pH 8. Bicarbonate is added

24

before the final adjustment of the pH of the water. Preferably the prepared reference waters are left to equilibrate with the atmosphere for some days (or even longer) before checking the pH and readjusting it if needed.

In the case of anoxic water, it can be prepared in atmospheric conditions up to adding all other components but silicate and bicarbonate. Preparation of the silicate solution as well as the addition of bicarbonate is performed inside the glove box, after which the final pH of the reference water is adjusted. Before taking them into the glove box, all the solutions are thoroughly flushed with an inert gas of low 0 2 (preferably :s;; 0.1 ppm) content to reduce the dissolved oxygen level in the solutions to about 1 o-6 M. All solutions (also ion-exchanged water) newly brought into the glove box are left to equilibrate for some time before use, at least some days, but depending on the amount of solution even longer equilibration periods are used, up to several weeks. If reducing agents are used to obtain reducing conditions in the reference water, these agents are, of course, added to the water in the glove box after the water has equilibrated with the glove-box atmosphere. This will prevent larger amounts of the reducing agents from becoming oxidized upon addition.

The exact amount of Na and er in the reference waters depends on the amount needed in adjusting the pH of the waters and thus in the tables below only Na and er originating from the chemicals is given. The pH value given in the tables is the theoretically obtained value to which the pH adjustment is made if necessary.

5.1 Fresh reference groundwater

The composition of the fresh reference groundwater (modified Allard water) is a modification of the so-called Allard water (Allard et al. 1981 ), which has also been used in experiments and especially in low C02 atmosphere, changes in the pH have been observed. In both conditions, oxic and anoxic, the modelling results indicated some over-saturation for the original Allard water composition. Equilibration resulted in the compositions given in Table 5-1. The table also includes the chemicals and the amounts needed to prepare the reference groundwaters.

Table 5-1. Composition of the fresh reference groundwater (modified Allard) water in oxic and anoxic conditions and the amounts of chemicals needed for making the waters.

FRESH REFERENCE GROUNDWATERS

Modified Allard Modified Allard Oxic (log Pc02=- 3.5) ALL-MO Anoxic (log Pc02=- 4.0) ALL-MR

composition chemical amount composition chemical amount [mg/L] [mmol/L] I [mg!L] [mg/L]. J [mmol/L] I [mg!L]

HC03- 90.7 1.5 NaHC03 I 124.91 65.0 I 1.1 NaHC03 I 89.56 I

Si02 2.9 0.05 NazSi03·9HzO I 13.76 1.7 0.03 Na2Si03·9Hz0 I 7.96 Na 52.5 2.3 NaCl ! 40.95 52.5 I 2.3 NaCl I 56.24

I I

r 3.9 0.10 KCl I 7.46 3.9 I 0.10 KCl I 7.46 Ca2+ 10.2 0.25 CaC}z·2H~ 37.54 5.1 0.13 CaC}z·2H20 I 18.85

.Mgt 2.8 0.11 MgC}z·6HzO I 2.88 0.7 0.03 MgC}z·6H20 I 5.97 sol- 9.6 0.10 MgS04·7HzO I 24.65 9.6 0.10 NazS04 I i4.20

I

er 47.5 1.3 I 48.8 I 1.4 I P Htheoretical 8.4 8.8

25

5.2 Saline reference groundwater

The saline reference groundwater (Vuorinen et al. 1997) is based on Olkiluoto groundwater sampled at the depth of 613-618 m in borehole KR1 (OL-KR1). Equilibration in anoxic conditions resulted in very low contents of bicarbonate and silicate, which were disregarded in the composition of the water. Otherwise the reference waters in both oxic (OL-SO water) and anoxic (OL-SR water) conditions have the same contents, given in Table 5-2 along with the amounts of chemicals needed for making the reference waters.

Table 5-2. The composition of saline reference groundwater in oxic and anoxic conditions and the amounts of chemicals needed for making the waters.

SALINE REFERENCE GROUNDWATERS

Oxic (log Pco2=- 3.5) OL-SO Anoxic (log Pco2= - 7 .0) OL-SR

composition chemical . amount composition chemical .. amount {mg/L] I {mmol/L] I [mWL] fmg/L] I {mmol/L] I [mg/L]

HCOi 10.0 I 0.16 NaHC03 I 13.83 - I - NaHC03 l -................................................................................................................................................................................................................................ , ............................................................................................ t·································································································"·········"···········t ... ··· .. ····························-········-· Si02 2.5 I 0.04 Na2Si03·9H20 i 11.83 - ! - Na2Si03·9H20 I -

5.3 Brine reference groundwaters

The brine reference groundwaters, presently two variants (OL-BRINE and OL-Br) in use, are based on ground water sample OL-KR4 (Appendix 2, Table A2-4) from Olkiluoto. The main differences in the water compositions are shown in Table 5-3. The OL-BRINE variant contains Mg2

+ but no silicate, whereas the OL-Br variant contains silicate but no Mg2

+. The HC03 .. , er and Ca2+ contents in OL-BRINE are son1ewhat

lower than in OL-Br. The measured pH values may deviate from the theoretical ones because of the salinity effect on the electrode.

26

Table 5-3. Composition of the brine reference groundwaters in oxic conditions and the amounts of chemicals needed for making the waters.

BRINE REFERENCE GROUNDWATERS

Oxic (log Pc02=- 3.5)

a) CL-BRINE b) OL-Br composition chemical amount composition chemical amount

[mg/L 1 I [mmo//L 1 [mg!L] [mgiL1 I [mmo//L1 I [mg!L] Heo3- 5.9 0.10 NaHC03 8.2 1.8 0.03 NaHC03 I

Na.,. 10000 435 NaCl 25 433 10000 434 NaCl ea~.,. 15400 384 CaCh·2H20 56482 17300 433 CaCh·2H20 er 43000 1212 46100 1299 Mr· 111 4.6 MgCh·6H20 921 Si02 I 5.6 0.09 Na2Si03·9H20 I pHtheoretical -7.1 -7.1

5.3 Brine near-field reference water

The brine near-field reference water is based on experiments and modelling of the interaction of bentonite and the brine reference groundwater, OL-BRINE (Muurinen et al. 1998). This water represents the short-term changes that occur when the groundwater has been in contact with bentonite long enough to become saturated but no remarkable migration of the soluble components has occurred yet. The measured pH in this water may deviate from the theoretical one for the same reasons as in the case of the brine reference groundwater. The compositions are the same in both conditions except for the amount of bicarbonate.

Table 5-4. Composition of the brine near-field reference water in oxic and anoxic conditions and the amounts of chemicals needed for making the water.

BRINE NEAR-FIELD REFERENCE WATER

2.5 25 355 63 601

26.3

Oxic (log pc02=- 3.5) OL-BNO Anoxic (log Pc02=- 4.0) OL-BNR

composition chemical amount composition chemical amount [mg!L1 [mmo/IL1 I [mg!L] [mg!L1 I [mmo//L1 I [mg/L]

Heo3- 8.4 0.14 NaHC03 I 11.5 4.8 0.08 NaHC03 6.6 Na+ 22 700 986 NaCl 57 599 22 700 986 NaCl 57 599 r 190 4.8 KCl 360 190 4.8 KCI 360 ea~.,. 9 900 I 247 CaCh·2H20 36 327 9 900 247 CaCh·2H20 I 36 327 ML_.,. 700 28.8 MgCh·6H20 3 254 700 28.8 MgCh·6H20 I 3 254 sol· 1200 12.8 MgS04·7H20 3 144 1200 12.8 MgS04·7H20 I 3 144 er 53 800 1516 53 800 1516 P Htheoretical 7.2 7.5

27

6 SUMMARY

Evaluation of the different groundwaters analyzed within the site investigation programme resulted in selecting four types of reference groundwaters for assessing the solubilities of the required radionuclides for the performance assessment TILA-99 (Vieno & Nordman 1999), that is, fresh, brackish, saline and brine. The compositions of the far-field reference waters selected are collected in Table 6-1. Only for the fresh reference groundwater are oxidizing conditions considered, as the possibility of glacial melt-water reaching the repository is one scenario in the performance assessment. Otherwise only reducing conditions are anticipated.

Table 6-1. The far-field reference waters for estimating solubility limits for TILA-99.

FRESH-RE FRESH-OX BRACKISH-RE SALINE.:.RE BRINE-RE

Eh range !m V -205--418 i +667- +489 I -205- -343 ! -195--340 I -195--340

~\i~~~~~fii~:; 3~!t~~~~~~~t~~~~~:::t~~~~:::~E~1£~ Ca !-"- 5.1 i 10 ! 680 j 4 000 ! 15 700 i~~~············································T=;;·=·············· ························s·2·······················r······················s·2·······················r···························2-·6·oa····························r····················4··s·O"a···· .. -··········-T·················9···7·scf················

-f~~::==:=Jg:::: :::iE5:=:E:::::=:::::=::F==::~:F:~::I=:-31E~]::::_~~~:=::::: .~J ............................................. J::.::.:: ................................... 9.:.~.?. ................... ..1 .................... 9.: .. ~?...................... 0. 048 .............. J .................... .9~.9..?..~ ....................... l. ................. 9.:.9.9.~ .................. . Mn !-"- 0.68 ! 0.68 J 2.3 ! 0.61 ! 2.2 "li~··············································p;·=··············· ········-··········a~·s·s················-··r··········-······o~·ss····················r············································································r······················<o3·······················r···· ................................................... . ·s·~·············································T=;;·= .. ············ ··················6 ... i.9K···············r················<i:.i9·6·················r············································································r··························3·s··············-·· .. ·······r···················i6·6··················· .. . c ................................................. c;;·= ................................ 6:·o34 ................ 'l ................. o:·o34 .................................................................................................. r ....................... o ... o2 ...................... 1 ..................... o .. ii ................. .. ........ ~ .............................................. 1... .................................................................................. 1 .. ,......................................................... .. .................. t ...................... :::: ..... : .............................. + ........................ : .............................. . . ~ .................................................. .!.::.::.:: ........................................................................ !"""""""""""""""""""""""""""'" .............................. ,J.. ...................... 9..:?. .. ~ ......................... 1 ...................... ..9.:.? ...................... . . N.!!.4. ...................................... .J.::.::.:: .................................... ..9.:.?. ...................... .L .................. 9.:..! .. ?. ........................................................ ! .. :.4. .................................. L ...................... 9..:.~4. ........................ .L .................. 9.:.9.~ .................... . Cl !-"- 52 i 47 5 290 ! 14 800 ! 43 000

~~~===]~~~~~~-=~~=E=:~3::=:=E~~E=:J~~r~:=E~~t:~=-• !-"- 0.41 i 0.41 i 0.05 i 0.85 ! 0.6

:?2~:::::::::::::::::~::::::::::::::~:::]~::.~:::::::::::::: ::::::::::::::::::::CE2:::::::::::::::::::r:::::::::::::::::::I:::E2:::::::::::::::::::r:~::::::::::~:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::[::::~::::::::::9:;I:?:~2:::::::::::::::::::::r::::::::::::::::~EE~2::::::::::::::::: S{-I!)tot !-"- 3**) ! ! 0.11 ! 0.03 ! 0.05 ·so ......................................... T=:·;;·= ............................... 9:6·~·;) ................ T ..................... 9·:·6 ...................... r ............................... ?To ................................ r ...................... o.:·s4·-· ................... r ..................... < .. T .................... .. ............ ..4 ......................................... ; ............................................................................................................................................................................................................................... ; ................................................................ + ....................................................... ..

~;~~!!!~~Jf1t_:::: :~::~::Q;QQ~~~]=~~=:l:::::~~:c--:::!:=-_:-_:_~~::::::::!::::::;:&-= TDS !mg!L 185 ! i 9 778 ! 24 000 ! 70 000

*) uncertain values due to analytical problems. **) these parameters are affected by the redox buffers acting in the system.

Two types of near-field reference waters were chosen as the experimental results on bentonite interaction with fresh and saline groundwater indicated that the effects on the brackish groundwater are bracketed by those of the fresh and saline groundwater. The compositions are given in Table 6-2. In the near-field, both anoxic and oxic conditions are considered for both reference waters. Oxidizing conditions will prevail for some hundreds of years after the closure of the repository, but the oxidizing conditions to be considered in safety assessment result from the failure of the spent-fuel canister bringing about oxidizing conditions close to the surface of the spent fuel as a result of aradiolysis. In other regions of the near-field reducing conditions are anticipated.

28

Table 6-2. The near-field reference waters for estimating solubility limits for TILA-99 . ..

I FRESH· FRESH- S,A.LINE- . SALINE-NEAR;.OX NEAR.;. RE NEAR~OX. . NEAR;.RE

..... P..!! ..................................................... ;.l.. ................................................................................... ?..:.9. .. ::::: .... !.9..:.9 ...................................................................................................... .?.:.9 ... ::::: .. ?..:.9. ................................................... .

..... ~t!!.t.~l. ...................................... J ..... ~ .................................................................... ?..:.~ .. ::::: ... ~.:.~ ........................................................................................................... ! .. :.4. ... ::::: . .9.: .. ~ ................................................... .

..... ~!~!!!!!.!! ...... ___ ; ........ .J ..... ~~~ ..................................................................... ?..:.9. ............................................................................................................................... !..:~ .............................................................. . SiOz I - " 23 10 ..... N; ....................................................... r···=····;;······ ........... ··························································~i"4oo·······························-························· ························································ii .. o66·········································· ............ .

........................................................................ t·······················"······························································································································································································································································································

.... .9.~ ... ~.-~.t ..................................... .L ... ~ ................................................................. 4..:.?. ... ::::: ... 9.:.9.~ .................................................. ················································~-~.:.~ ... :::::.}.~.:.~ ............................................... .

..... MK ................................................... L .. ~~---······· ................................................................ ?..~ ............................................................................................................................... ~.4..9 ............................................................. . AI I - " 0.8 0.2 -··M:""ii---·--·-·--··--·--·---·r··=····;;·····-·········· ·······························································o~7·································· .. ··························· ................................................................ 2~·6······························ ................................ .

····n~ ....................................................... t···=····;;·····-·········· ............................................................... ojf····································-······················· .............................................................. i7 .............................................................. . ..... s;············· ............................................ r··=·····;;······-······· ............................................................... 0~3·······································-·······-·············· ................................................................. 61 ............................................................... .

·····c~ .. ···--····················-·························r···=·····;;················· ·····························································<i.o4····························································· ............................................................... o.:i··························· ................................. .

..... n .......................................... ·-··············r···=····;;················· ............................................................... 0~3································································ ······························-·············-··········-·-·i~·?·········-·-·················································

:::::~~:::::::::::::::::::~:::::::::::::::::::::::~::~1::~::::~~::~:~::::::: ::::::::::::::::::::::::::::::~:::::::::::::::::::::::::::::::r:::::::::::::::::::::::::::::q;:?.::::::::::::::::::~:::::::::: :~:~::::::::::::::::::::::~:::::::::::::::::::::::::::::r:::::::::::::::::::::::::::::?E?.:::::::::::::::::::::::::::::::: Cl I - " 420 17 000 ..... F" ............................................................................ ;;····-·········· ···························-··································6-~i ............................................................................................................................... :r·s····-····· ................................................... .

........... --···---.. --- ................................... ·········································································································································· ·······················································-···········································-············· .. ····················· Br 1 - " 3.0 140

!!~~~~~~~¥~~~~~~~~ *) gives Ctot range as computed assuming calcite equilibrium in the water at the pH range indicated **) gives the range of Ca content corresponding in the calcite equilibrated water #) Uncertain values due to analytical problems, more detailed consideration in connection with evaluating the solubilities (Vuorinen et al. 1998)

In addition to the reference waters for the safety assessment TILA-99 (Vieno & Nordman, 1999), this report also includes instructions for the preparation of some synthetic reference waters to be used in experimental studies. The compositions of the synthetic waters are adjusted to the conditions ( oxic and anoxic) in which the experiments are performed. Table 6-3 gives the compositions and chemicals needed to prepare the synthetic reference waters.

~"""""'-"-----------------·------

29

Table 6-3. Composition of the synthetic reference waters for experiments and chemicals and amounts needed to prepare the waters.

FRESH REFERENCE GROUNDW ATERS

Modified Allard Modified Allard Oxic (log Pc02=- 3.5) ALL-MO Anoxic (log Pco2= - 4.0) ALL-MR

composition chemical amount composition chemical amount [mg/L] I [mmol/L] [mg!L] [mg/L] I [mmol/L] [mg/L]

He03" 90.7 i 1.5 NaHC03 124.91 65.0 1.1 NaHC03 89.56 Si02 2.9 0.05 Na2Si03·9H20 13.76 1.7 0.03 Na2Si03·9H20 7.96 Na 52.5 I 2.3 NaCl 40.95 52.5 2.3 NaCl 56.24 K 3.9 0.10 KCl 7.46 3.9 0.10 KCl 7.46 etr.,. 10.2 I 0.25 CaCh·2H20 37.54 5.1 0.13 CaCl2·2H20 18.85

M~ 2.8 I 0.11 MgCl2·6H20 2.88 0.7 0.03 MgC12·6H20 5.97 SO./" 9.6 0.10 MgS04·7H20 24.65 9.6 0.10 Na2S04 I 14.20

er 47.5 1.3 48.8 1.4

pHtheoretklll 8.4 8.8 SALINE REFERENCE GROUNDWATERS

Oxic (log Pco2=- 3.5) OL-SO Anoxic (log Pco2= -7.0) OL-SR

composition chemical amount composition chemical amount [mg/L] I [mmol/L] [mg/L] [mg/L] [mmol!L] [mg!L]

He03" 10.0 I 0.16 NaHC03 13.83 - - NaHC03 -Si02 2.5 0.04 Na2Si03·9H20 11.83 - - Na2Si03·9H20 -Na 4800 209.1 NaCl 12119.3 4800 208.8 NaCl 12115.7 r 21.0 0.54 KCl 39.54 21 0.54 KCl 39.55 etr· 4000 99.8 CaCh·2H20 14672.2 4000 100 CaC12·2H20 ! 14672.2 Mr· 55.9 I 2.3 MgCh·6H20 467.6 54.6 2.3 MgCh·6H20 I 456.5 sr.,. 35.0 I 0.40 SrCl2·6H20 106.7 35.0 0.40 SrCl2·6H20 I 106.5 ~~ 0.92 I 0.08 H3B03 5.26 0.92 0.08 H3B03 I 5.26 SO/" 4.2 0.044 Na2S04 6.21 4.2 0.044 Na2S04 ! 6.21 er 14 500 412.9 14 500 412.7 F 1.2 i 0.063 NaF 2.63 1.2 0.063 NaF 2.63 Br" 104.7 I 1.31 NaBr 134.8 104.7 1.31 NaBr 134.8 I 0.9 0.007 KI 1.11 0.9 0.007 KI 1.11

PH theoreticlll 7.2 8.3 BRINE REFERENCE GROUNDWATERS

Oxic (log Pc02=- 3.5)

OL-BRINE OL-Br composition chemical amount composition chemical amount

[mg!L] [mmol/L] [mg!L] [mg/L] I [mmol/L] I [mg/L] He03" 5.9 0.10 NaHC03 8.2 1.8 0.03 NaHC03 I 2.5 Na.,. 10000 435 NaCl 25 433 10000 434 NaCl I 25 355 etr.,. 15400 384 CaC12·2H20 56 482 17300 433 CaC12·2H20 I 63 601 er 43000 1212 46100 1299 M?.,. 111 4.6 MgCh·6H20 921 I Si02 5.6 0.09 Na2Si03·9H20 26.3

pHtheoreticlll -7.1 -7.1 BRINE NEAR-FIELD REFERENCE WATER

Oxic (log Pco2=- 3.5) OL-BNO Anoxic (log Pco2= - 4.0) OL-BNR

composition chemical amount composition chemical amount [mg/L] I [mmol/L] I [mg/L] [mg!L] I {mmol/L] I [mg/L]

Heo1- 8.4 I 0.14 NaHC03 11.5 4.8 0.08 NaHC03 i 6.6 !

Na.,. 22 700 986 NaCl 57 599 22 700 986 NaCl 57 599 r 190 4.8 KCl 360 190 4.8 KCl 360 etr· 9 900 247 CaC12·2H20 36 327 9 900 247 CaC12·2H20 I 36327 Mr· 700 28.8 MgCh·6H20 3 254 700 28.8 MgCl2·6H20 3 254 SO/- 1200 12.8 MgS04·7H20 3 144 1200 12.8 MgS04·7H20 3 144 er 53800 1516 53800 1516

PHtheoretklll 7.2 7.5

30

7 REFERENCES

ALLARD, B., LARSSON, S.A., ALBINSSON, Y., TULLBORG, E-L., KARLSSON, M., ANDERSSON, K. & TORSTENFELT, B. (1981). Minerals and precipitates in fractures and their effects ion the retention of radionuclides in crystalline rocks. In: Proceedings of the NEA Workshop, Near-field phenomena in geologic repositories for radioactive waste, Seattle, USA. Paris, France: NEA, pp.93-101. ISBN 92-64-02236-8.

APPELO, C.A.J & POSTMA, D. (1993). Geochemistry, groundwater and pollution. Rotterdam, Netherlands: A. A. Balkema, p. 536. ISBN 90 5410 1067

DAVIS, S.N. (1964). The chemistry of saline waters. In Krieger, R.A. - Discussion. Groundwater, vol. 2(1), p.51.

DREVER, J.I. (1982). The Geochemistry of Natural Waters. Englewood Cliffs, N.J., USA: Prentice-Hall Inc., p. 288. ISBN 0-13-351403-X

BERNER, R.A. ( 1981 ). A new geochemical classification of sedimentary environments. J. Sed. Petrol. 51, 2, pp. 359-365.

HEIKKINEN, E., SAKSA, P., RUOTSALAINEN, P., AHOKAS, H. & NUMMELA. J. (1996). Volumetric model of salinity of the groundwaters in Olkiluoto investigation site. Helsinki, Finland: Posiva Oy, Tyoraportti PATU 96-09, p. 52. (In Finnish with English abstract).

HAVEMAN; S., PEDERSEN, K. & RUOTSALAINEN, P. (1998). Geomicrobiological investigations of groundwaters from Olkiuoto, Hastholmen, Kivetty and Romuvaara, Finland. Helsinki, Finland: Posiva Oy, POSIV A 98-09, p. 40. ISBN 951-652-047-2, ISSN 1239-3096.

KANKAINEN, T. (1986). Loviisa power station, final disposal of reactor waste. On the age and origin of groundwater from the rapakivi granite on the island of Hastholmen. Helsinki, Finland: Nuclear Waste Commission of Finnish Power Companies, Report YJT -86-29, p. 56. ISSN-0359-548X.

LEHIKOINEN, J. (1999). Ion diffusion in compacted bentonite. Helsinki: Posiva Oy. 37 p. (POSIV A 99-21). ISBN 951-652-076-6

LEHIKOINEN, J., CARLSSON, T., MUURINEN, A., OLIN, M & SALONEN, P. ( 1996). Evaluation of factors affecting diffusion in compacted bentonite. In: Murphy, W.M. & Knecht, D.A. (eds.) Proceedings of the Symposium on Scientific Basis for Nuclear Waste Management XIX, Nov. 27-Dec.l 1995, Boston, New York, USA: Material Research Society Pittsburgh, Pennsylvania, Vol. 412, pp. 675-682. ISBN 1-55899-315-0.

MUURINEN, A. (1997). Model for diffusion and porewater chemistry in compacted bentonite - preliminary results of the porewater chemistry studies. Helsinki, Finland: Posiva Oy, Tyoraportti 97-62e, p. 26.

MUURINEN, A., AALTO, H., CARLSSON, T., LEHIKOINEN, J., MELAMED, A., OLIN, M. & SALONEN, P. (1995). Interaction of fresh and saline waters with compacted bentonite. Espoo, Finland: Technical Research Centre of Finland, VTT Research Notes 1714, 29p. + app, ISBN 951-38-4869-8.

31

MUURINEN, A. & LEHIKOINEN, J. (1999). Porewater chemistry in compacted bentonite. Helsinki: Posiva Oy. 34 p. + app. 12 p. (POSN A 99-20). ISBN 951-652-075-8

MUURINEN, A., VUORINEN, U, LEHIKOINEN, J. & AALTO, H. (1998). Development of saline near-field reference water. Helsinki, Finland: Posiva Oy, Tyoraportti 98-03, p. 18. (In Finnish with English abstract).

MULLER-VONMOOS, M. & KAHR, G. (1983). Mineralogische Untersuchungen von Wyoming Bentonit MX-80 und Montigel. Baden, Switzerland, NAGRA, NTB 83-12, p. 15 + app. p.13.

OLLILA, K. (1998). Dissolution of unirradiated U02 fuel in synthetic groundwater-Progress report '97. Helsinki, Finland: Posiva Oy, Report POSN A 98-06, p. 17+app. ISBN 951-652-044-8, ISSN 1239-3096.

PEDERSEN, K. & KARLSSON, F. (1995). Investigations of subterranean microorganisms - their importance for performance assessment of radioactive waste disposal. Stockholm, Sweden: Swedish Nuclear Fuel and waste Management Co. Report SKB TR-95-10, p. 222.

PITKANEN, P., SNELLMAN, M., LEINO-FORSMAN, H. & VUORINEN, U. (1994). Geochemical modelling of the Olkiluoto site. Helsinki, Finland: Nuclear Waste Commision of Finnish Power Companies, Report YJT-94-10. p. 79+app. ISSN-0359-548X.

PITKANEN, P., SNELLMAN, M. & VUORINEN, U. (1996a). On the origin and chemical evolution of groundwater at the Olkiluoto site. Helsinki, Finland: Posiva Oy, Report POSN A-96-04, p. 41+app. ISBN 951-652-003-0, ISSN 1239-3096.

PITKANEN, P., SNELLMAN, M., VUORINEN, U. & LEINO-FORSMAN, H. (1996b). Geochemical modelling study on the age and evolution of groundwater at the Romuvaara site. Helsinki, Finland: Posiva Oy, Report POSN A-96-06, p. 121+app. ISBN 951-652-005-7, ISSN 1239-3096.

PITKANEN, P. & SNELLMAN, M. (1997). Stability of fresh ground waters, In Proceedings of the Workshop on Hydrogeochemical Stability and Origin and Evolution of Deep Saline Ground waters, Mala, Sweden. 17-18 March, 1997. Aspo Progress Report HRL-97-25.

PITKANEN, P., LUUKKONEN, A., RUOTSALAINEN,P., LEINO-FORSMAN, H. & VUORINEN, U. (1998), Geochemical modelling of groundwater evolution and residence time at the Kivetty site. Helsinki, Finland: Posiva Oy, Report POSN A-98-07 p.139, ISBN 951-652-045-6, ISSN 1239-3096.

RUOTSALAINEN, P. & ALHONMAKI-AALONEN. S. (1996). Pohjavesinaytteiden otto letkunaytteenottimella Eurajoen Olkiluodon kairanrei 'ista KR2, KR4 ja KR10, Posiva Oy, Helsinki, Tyoraportti PATU-96-81.

RUOTSALAINEN, P. & SNELLMAN, M. (1996). Hydrogeochemical baseline characterisation at Romuvaara, Kivetty and Olkiluoto, Finland. Posiva Oy, Helsinki, Work report PATU-96-91e.

32

STROES-GASCOYNE, S. & WEST, J.M. (1994). Microbial issues pertaining to the Canadian concept for the disposal of nuclear fuel waste. Pinawa (Manitoba) Canada: AECL. Report AECL-10808, COG-93-54, p.39. ISBN 0-660-15508-7, ISSN 0067-0367.

WERSIN, P, SPAHIU, K. & BRUNO, J. (1994). Time evolution of dissolved oxygen and redox conditions in a HLW repository. Stockholm, Sweden: Swedish Nuclear Fuel and waste Management Co. Report SKB-TR-94-02.

VIENO, T. & NORDMAN, H. (1999). Safety assessment of spent fuel disposal in Hastholmen, Kivetty, Olkiluoto and Romuvaara. Helsinki, Finland: Posiva Oy, Report POSIV A-99-07 p.253, ISBN 951-652-062-6, ISSN 1239-3096.

WOLERY T.J., (1992). EQ3/6, A Software Package for Geochemical Modeling of Aqueous Systems (Version 7 .0). Livermore, CA, USA: Lawrence Livermore National Laboratory. UCRL-MA-110662 PT I-IV (PT I, September 14, 1992, 66 p.; PT IT December 17, 1992 89 p.; PT ID, September 14, 1992,246 p.; PT IV, October 9, 1992, 338 p.)

VUORINEN, U., OLLILA, K. & SNELLMAN, M. (1997). Groundwater Chemistry at Olkiluoto-saline and brackish groundwater-recipe for saline reference water. Helsinki, Finland: Posiva Oy Tyoraportti 97-25. p. 59. (In Finnish with English abstract).

33

APPENDIX 1: Some trace element concentrations in groundwater samples.

Table Al-l. Trace element concentrations measured in some groundwater samples at three investigation sites. (RO=Romuvaara, Kl=Kivetty, OL=Olkiluoto).

Date Sec. up Sec. low Cu Zr Pb Ni Co Hg

Site Year (ddmmyy) (m) (m) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (ug/L)

RO 87 031287 644.6 650 0.030 <0.002 <0.010 <0.005 0.090

RO 90 101090 460 502 <0.005 0.012 <0.05 <0.005 <0.005 <0.2 RO 91 250691 460 502 <0.005 0.010 <0.05 <0.01 <0.02 0.800

Kl 88 301188 819 830.5 <0.001 0.002 <0.001 <0.01 <0.002 <0.05 Kl 88 071288 169 180.5 <0.001 0.002 <0.001 <0.01 <0.002 <0.05 Kl 88 131288 169 180.5 <0.001 0.002 <0.001 <0.01 <0.002 <0.05

Kl 91 210891 190 250 <0.005 0.010 <0.05 <0.01 <0.02 0.600 Kl 91 291091 170 180.3 <0.005 0.005 <0.05 <0.01 <0.01 0.500

OL 89 031189 160.5 165.5 0.007 <0.005 <0.05 0.024 <0.005 0.400

OL 89 161189 140 145 <0.005 <0.005 <0.05 <0.005 <0.005 <0.2

OL 89 281189 140 145 <0.005 <0.005 <0.05 <0.005 <0.005 <0.2 OL 90 070290 613.5 618.5 <0.005 0.025 0.069 0.026 0.011 <0.0002 OL 90 070290 613.5 618.5 <0.005 <0.005 0.057 0.022 0.008 <0.0002

OL 90 210290 613.5 618.5 <0.005 <0.005 0.079 0.023 0.011 <0.0002 OL 90 210290 613.5 618.5 <0.005 <0.005 0.094 0.034 0.014 <0.0002

OL 90 280290 613.5 618.5 <0.005 <0.005 0.096 0.033 0.015 <0.0002 OL 90 280690 754 1001 <0.005 <0.005 0.053 0.059 0.011 <0.0002 OL 90 270790 754 1001 0.010 <0.005 <0,05 0.026 0.012 <0.0002 OL 91 250491 754 1001 <0.005 0.010 <0,1 0.020 <0.2 <0.002 OL 90 240490 235 240 0.006 <0.005 <0.05 <0.005 <0.005 <0.0002

OL 90 080590 235 240 <0.005 <0.005 <0.05 <0.005 <0.005 <0.0002

OL 90 220590 388 393 <0.005 <0.005 <0.05 <0.005 <0.005 <0.0002

OL 90 070690 388 393 <0.005 <0.005 <0.05 <0.005 <0.005 <0.0002

OL 92 110692 446 558.85 <0.005 <0.005 <0.05 0.010 <0.01 <0.0002 Date Sec. up Sec. low Ti Cr Mo Li V Be

Site Year (ddmmyy) (m) (m) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)

RO 87 31287 644.6 650 0.020 0.004 0.070 <0.01 <0.020 <0.05 RO 90 101090 460 502 <0.005 0.007 0.027 <0.005 <0.005 <0.001 RO 91 250691 460 502 <0.01 <0.02 <0.02 <0.01 <0.01 <0.01 Kl 88 301188 819 830.5 <0.01 <0.001 0.031 <0.02 <0.02 <0.05 Kl 88 71288 169 180.5 <0.01 <0.001 0.067 <0.02 <0.02 <0.05 Kl 88 131288 169 180.5 <0.01 <0.001 0.055 <0.02 <0.02 <0.05 Kl 91 210891 190 250 <0.01 <0.02 0.03 0.01 <0.01 <0.01 Kl 91 291091 170 180.3 <0.01 <0.01 0.020 0.010 <0,01 <0.005 OL 89 31189 160.5 165.5 <0.005 <0.005 0.140 0.017 <0.005 <0.001 OL 89 161189 140 145 <0.005 <0.005 <0.005 0.028 <0.005 <0.001 OL 89 281189 140 145 <0.005 <0.005 <0.005 0.029 <0.005 <0.001 OL 90 70290 613.5 618.5 <0.005 <0.005 0.019 0.013 0.019 0.001 OL 90 70290 613.5 618.5 <0.005 <0.005 0.016 0.013 0.018 0.001 OL 90 210290 613.5 618.5 <0.005 <0.005 0.015 0.017 0.022 0.001 OL 90 210290 613.5 618.5 <0.005 <0.005 0.016 0.017 0.027 0.001 OL 90 280290 613.5 618.5 <0.005 0.007 0.015 0.019 0.027 0.001

OL 90 280690 754 1 001 <0.005 0.016 0.040 0.062 0.015 <0.001

OL 90 270790 754 1 001 <0.005 <0.005 0.031 0.040 0.018 <0.001 OL 91 250491 754 1 001 <0.01 <0.02 <0.02 0.050 0.010 <0.01 OL 90 240490 235 240 <0.005 <0.005 <0.005 0.015 <0.005 <0.001

OL 90 80590 235 240 <0.005 0.006 <0.005 0.041 <0.005 <0.001

OL 90 220590 388 393 <0.005 0.005 0.133 0.280 <0.005 <0.001

OL 90 70690 388 393 <0.005 <0.005 0.044 0.012 <0.005 <0.001 OL 92 110692 446 558.85 <0.01 <0.01 <0.01 0.030 <0.01 <0.01

34

Table Al-2. Lanthanide concentrations measured in some groundwater samples at three investigation sites. (RO=Romuvaara, Kl=Kivetty, OL=Olkiluoto, KR=borehole, T=sampling section).

~~~eil~IJ~rello tl ]late -•• Sec.lll Sec. Jo, ··- ••:: ••. _._1_ 3p: 9pLb .. a··-··-··· ·-:. ···•· _•_t_·-····4P•_·_op __ -_ c_.b.· ___ e·_ ••••• _ •••• _-_ .•••••. A_·_ .•• P4Pl ..• _pb···-·~- ; .· A46N,f • • . ]41$1Jl . J. SP •• _l_._._P •• _Eb .. _ u 157Gd Leyet · •(~~J1lll)y: } (D1) ·· · (m) _. _.· > ·ppb • ppJJ>: : .· .. · _.· < pp~

·. RO~KR:t/£4.. 301193 145.0< 175.00 0.01780 0.02240 0.01500 0.09210 0.10300 0.02940 0.08520

Ro-KR2fl'~ 150294 345.(}( 375.oo o.o1o5o 0.01720 0.01000 0.01060 0.00513 0.01000 0.01000

Ro-KR2tr.~ 190893 375.(}( 415.oo o.o137o 0.01740 0.01000 0.01000 0.01000 0.01000 0.01000

. RO-:KR3!f .. 090694 415.0< 476.00 0.01000 0.01710 0.01000 0.01000 0.01000 0.01000 0.01000

. RO~KR4/1].. 090694 160.0( 210.00 0.01690 0.04140 0.01000 0.01000 0.01000 0.03940 0.01000

<RO~KRsrr . 130594 305.0< 330.00 0.01000 0.02510 o.01000 0.01000 0.01000 0.01000 0.01000

10-lfRttr~.. 020594 300.(}( 345.00 0.01000 0.02760 0.01000 0.01000 0.01000 0.01000 0.01000

10-J(l{l{fJ •· 050494 720.(}( 795.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

Ki-~~ 100294 75.00 155.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

)(i•.Kltiff4 020694 190.(}( 250.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

:KJ-.IdQ/f? 150694 85.00 130.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

>I{t-~/1:'3 ·. 100294 340.(}( 410.00 0.01490 0.02730 0.01000 0.01000 0.01000 0.01000 0.01000

l{I-I{R;4/fl•: 020594 430.(}( 500.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

:KI~AAS/f4 221193 300.0< 350.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

·. l{f-~5 220894 735.(}( 853.00 0.03000 0.03000 0.03000 0.03000 0.03000 0.03000 0.03000

QL-RR..t!f· 290395 76.00 126.00 o.o6ooo o.o6ooo o.o6ooo o.o6ooo o.o6ooo o.o6ooo o.o6ooo

OL-KQ:tff3 . 150295 612.00 618.00 0.80000 0.80000 0.80000 0.80000 0.80000 0.80000 0.80000

Oki(R4(f5 I 130395 107.00 132.00 0.20000 0.20000 0.20000 0.20000 0.20000 0.20000 0.20000

OL-KRSitt :: 290395 446.00 550.00 0.50000 0.50000 0.50000 0.50000 0.50000 0.50000 0.50000

!\tea~Boteholev:•<: ])ate:·· .. Sec. up • Sec>Iow •• lS9Tb···· l6ZDY···-• :·- l6SH~·· •·:·-••t66Et• 169Tm :·-· l74Vb ..• ·. __ t15Lu·<. > Level . • (ddmmyy ·. (m) ·. {rn) ppb ··ppb" ••··.: <.P(lb··· . < <ppb·--••· :·

1>·-.. : PPb<·.·· .: ppb.:·. ·.·: ppb · .. ·.

R.O~f(Rtfl'6 301193 145.00 175.00 0.01430 0.05610 0.01100 0.04010 0.01260 0.03940 0.01440

-RO:.KR2lf3 150294 345.00 375.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

RO~I<Rltrl 190893 375.00 415.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

RO~KRJr:iT 090694 415.00 476.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

RQ;;IQt4tf6 .· 090694 160.00 210.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

RO-KR5rt4 .·· 130594 305.00 330.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 ...........

IQ;;.i(Rlff(;< 020594 300.00 345.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

KI-KIU/'l'J" I 050494 720.00 795.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

la-K1Urr6 ·· 1oo294 75.oo 155.oo o.o10oo 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

K14(1U/f4 020694 190.00 250.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

K14<R3!f7 150694 85.oo 130.00 o.o1ooo 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

KI-.I<RJirJ 1oo294 34o.oo 41o.oo o.o1ooo 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

KI~AA4trt · 020594 43o.oo 5oo.oo o.o1ooo 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

J{I:.KRS!f4 221193 300.00 350.00 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000

Ki;;;KR.s 220894 735.00 853.00 0.03000 0.03000 0.03000 0.03000 0.03000 0.03000 0.03000

OL~KR:irt7 . 290395 76.00 126.00 0.06000 0.06000 0.06000 0.06000 0.06000 0.06000 0.06000

OL;.K.Rtli'J 150295 612.00 618.00 0.80000 0.80000 0.80000 0.80000 0.80000 0.80000 0.80000

OkKR4tf5 130395 107.00 132.00 0.20000 0.20000 0.20000 0.20000 0.20000 0.20000 0.20000 . . . . . . . . . . . . '

OL-'l<RSffl·· 290395 446.00 550.00 0.50000 0.50000 0.50000 0.50000 0.50000 0.50000 0.50000

Italic Bold Blank cell

below detection limit uncertain value not detected

35

Al-3. Measured Th and U concentrations and Th isotope ratios in the groundwater samples from three sites. (RO=Romuvaara, Kl=Kivetty, OL=Olkiluoto)

A:rea.;~()re.ijole Sec. tiP > piJ: Alk•• ·~h Rleasuhid•· Th2~81Tb2~2 T~228fTh2.~2 > IJ'"~34+{]-~~8. >U/Tb·· {;ever • · · <ltlr · · (meq) .••.•. >(ltlVj . . <>(M)< ··.····.·•>(1\f)>·.· ..

415.00 8.9 1.00 -170 200 7.9E-09 2.1E-09 0.266

160.00 9.4 1.40 47 2 2.2E-08 1.9E-09 0.088

305.00 10.1 1.70 130 4.14 3.8E-08 l.OE-09 0.027

•• KI-KIUff6 300.00 7.8 2.10 80 31 1.3E-08 2.9E-07 21.957

85.00 8.1 1.22 18 1.6E-08 4.7E-08 2.984

430.00 8.3 1.49 -35 12.29 9.6E-09 1.5E-07 15.418

735.00 8.8 1.30 -75 18.8 6./E-09 1.5E-08 2.485

76.00 7.6 6.10 120 90 7.9E-09 3.9E-08 4.989

612.00 8.3 0.33 -270 971 4.7E-08 1.7E-10 0.004

107.00 7.6 1.51 140 254 1.3E-07 7.3E-08 0.574

446.00 8.5 0.12 -250 630 3.2E-08 5.6E-10 0.017

Italic below detection limit Bold uncertain value

36

APPENDIX 2: Data on Finnish groundwater-types and the corresponding reference waters.

Table A2-1. The fresh reference water (modified Allard) and groundwaters from Romuvaara and Kivetty and the basic ALLARD water (Allard et al. 1981).

37

Table A2-2. Brackish reference water.

reference water

HH-KRJ

~:E:=!=t~~-=!~ }tbCIJ4ZEICQ;J1-"- i i ! ! -280

~=r-1~~~-f:f;-~ ~~:=~~~-~=w:::t=:~~=H=-.~~--···-'""~-·-'"···-L ..... : ... E::~:~:~:~::::: ::::::::::~~:9~:::::::::r::::~:~:I:9~9.:::::::::I:::~:::!I9~:~:~:: ~::~~::§j~::~:~:~t~::~?.~Q=:r~!Jos=~~ ==~:~~=~= Na i-"- 1 725 1 2 690 1 soo 2 500 1 2 600 1 1 380 2 600

.M~ . ..L .... w ...... LI.L .. :.E~:~:~::::~::::: :::~::::~~:;:~::::::::::r::::~::~:::~:~9:::::~::::::I:~:~:::~~:~~~::~:~: :~:~:~~~I=~:I~:~1~§_=]=~4o --· -~~~=~~I~~~---K .................. 1-"- 10.5 I 38 I 4.7 26 I 32 I 24 26

~£~lkBi~~~ Mn ........ ·.. . i-"- 0.25 I 1.2 I 0.012 2 I 3.2 1 1.86 2.3

.~l~ ... : ...... : .. "-~ ....... : ............... ...J:~::.~~::::::::::::: :::::::::~9.;:~:::::::::r::::::::::::~9:;:~:::~:~~::r···o-~o-o1~:~:~: :~::~=:::~:~:~:~:~:~:~[~~=:~~:~:=[=~=~:~=~=- :~-=~~:~:~~==~=~-sr . . !-"- 5.2 i 8.7 1.2 6.2 ! 7 i 4.95 ~,..-• •··-· .-• .. ~···················-······· ························-·······-r·················-··········-··········· ·-···· ························-·-··--r···--··----·---·-r·---------· ----··-·-·-····--·-·--.S~-·-···""':···-·····-···"; .......... J:.::.: ..................... .9.:.9.9.~ ..... ...1 ..... -..... 9.:.9..!.............. o. oo2 ................................... ! ·····-·--··-·-······+---··--·-·--- ··-·-·------·-·--·--·--u ......•.•• ' ...... 1-"- 0.9 I 1.5 1 1.12 2 I 0.08

=~11Ttllll~ Br · ·· !-"- 17 i 43 i 1.5 19.1 I 28 1 14.4 16 .~.;;..;.,;.;;...;;..;.,;.;;..~ ............................ ························-·········r······················--··-············r···············-·················· -·-·-···········-·--··--·r·--·----·--+-·---·--·--·· -·-·----------·-·-·

.!.. ............. ; ....................... L ..... J.:.::.: ..................... .9.: .. ! .. ~.?.. ....... L. ........... .9.: .. ?. ................ L .... .9..:9.! ................... 9:.9.?. ......... .L ..... .9.:.Q.~---·j __ p.04_~---· --·----~92 ______ _ N();{ *) > I-"- 0.145 ! 0.44 ! 0.01 I I <0.02 0.02 ............................... ························-·········•··································-······•··-······························· ····--·························T······-·-·-··-·-·-·-·-··r·--·····---·--·--· ···-·-·-·-·----·-·-····-·--NQa ~> !-"- o.o2 I 0.04 I o i I <0.02 0.02 ·r~ ......... *r··~·-··-··---··1:~:::~:::::::::::::: :::::::::::9~I:~:::]:::::::::::::::9.~~:::::::::::::::r:::::::9~9I:::~::: ::~:~::::::::::::::::::::~:r~:~~:~~::~::=I~~~~fi~~ :~~:==::~~~~~==~ ~(-D)tot !-"- o.o5 I 1.8(3?) I 0.01 1 0.11 1 <0.01 0.11 'so~·--·7 ....... -.T--··--·~·····,·::::·;·;:···········-· .......... 23··c-·····r·············s·6a·········-···t·········-·1":·4----···· ·····-···6so-·······r·····-71o·-··r--4oo-- ------·-7J.o·--·-·-

~ij~tl~~i~~ 'l'b'-~31 i~g/L i 0.0036*) I 0.002*) i I

:!!t~~{~l! ............... {::::::~:::::::~:~:::::: :::::::::::::::::::::::::::::]:::::::~~:i:~x:::::I::::29.:~E::::: ~:~::::::=~:~~~:~]:~:::~~~~~::::~~+---~::~~-~=:~: ===:~:~~~~~~~= La...;l3~ !~giL n.d. I n.d. i n.d. !

~=:=~~~~=E!( __ 31~~= Rn IBq/L 55.5 I 310 I 8 390 ! 510 r 240

~~~~~==l~~EI:::1~m:;:=~~ :=io~ C()z 1-"- 0.14 I 0.15 I 0.06 I 1.14*) I 1.14*)

~-=+=~=:=~:otEJ~~=~~ TDS lmg!L 6 649 I 9 377 I 2 098 9 118 I 9 778 I 6 762 9 778

*) uncertain values due to analytical problems. Italic below detection limit n.d. not detected

38

Table A2-3. Saline reference water.

OLKILUOTO HlsmoL'MEN Sllllne refehn~ Sllline reference water Saline Saline water f~r el:pel'imenl$

Median Max Min Median Max Min OL-KRl OL-SR

*) uncertain values due to analytical problems. n.d not detected n.a not analyzed Italic below detection limit

39

Table A2-4. Brine reference water.

······· .. ·.• ................. ····· ·•• ........ ••• • ·· ·• ·· · ? ()~-}lfi~e ···· ••.·· · .. ·•·· <·.· •·••·• .. · ....... <·• .• OL-KR4 /> ,m 861 1~-";~~~-l. .. ;-'"~·-····..::.cL ... :. .... r~:~ .................................... l ......................................................................... .

~-~~~~~~~~~-'·.J···• .. ·--··.·~ ... · .. •·-· •.•· .. • ... ~i[_ m~1~ V'Y. ................................ t .............................. ~-~-~2... ......................... .. ..... .•• < ... .. .......................... ?..:.~.~) .......................... ..

~~l~i~~L~l~~}[J·J ·2····:•a•·· m~~eq~IL~:::::::~:::~::::::t ............................... .9.:.~ ............................... . •··•· \.. ·mg/L 1.0 h·cc'-"'"'·"-"'·cccc .. • .... ccc.;c'-.-' .. •'•••·••+ .. ·-··;::: ................................ 1 .......................................................................... .

> < ···•••·•··· .. ,_ 5.3 t··~;;;,,,;~,,.,-., .. ,.., .. "' .. "''-""""'1·-.. --.................................... , .......................................................................... .

j:lt'-!L.••..:•• •• L.r:L .•. •,' .. •.· ___ ,..._ ••. ::.·:..,..,:_~··,: ····"·j· m~~~-~17/~l~ ........................ l ....................... .J .. ?. .... ?QQ ........................ . ••••••••.•. ........ . > •••.•• -· 9 750

~-'=-+'r'""'""• .-.. ·.·.-•. , ......... "'"'"." <''"'.' .~ .... , •.. :., ••• • .•. +_ ........................................... , ............................... iio ............................. . h+"~•'+c;-'hc:c+H+c:•:;,.;,.•.·•"+ .......................................... , .......................................................................... .

<• > >:.·· -"· 22 1·±+±+·~~++-++,.;:-+"·'·"+""''"''"'""""'"'"'"'"'"'""""""'""'""+"'"''""'"""'"'"'"'""'"'"''"'"""'"""'"'""'"'""'"'"""'""""'

l·~~tij>-~.. •••.. > > =n ............................. ~:f-?. ............................ .. ""+~-~.~ ....... ; .. ; ... ·~ .·.··"··•··;"'.~ ..• ~ .• ; •.•...• ;,.;., ...... ; .. /'·""1 .. _ ........................................... , ........................... o~oo3 .......................... . l•:•"''"''"'"'"""''·;"~:f•',.;c,-.,.,••·•'••·•'·'·"+ ......................................... , .......................................................................... .

!.·· •.. ·· .. •··· ··•·•··• -"· 2.2 I•±•::~"';+'•:+·H,•···~:··:••·:"·~··•·• ... ; ........................................... , ......................................................................... .. ···•··· •·•· ...... , .:·, •········T- 160 h~··,.,••i'"'~;-····-~-.,. ......... ~·-·~···~·-:·'"-i"'"'"'""'"""""'""""""""""'"""''l"''"'"""""'""'""""'""'"'"'"'"""'""'"'"""'"'"'"'"'"'""'"'

:~ <'.............. > .... - 0.12 1-~~;,.~:-:-·•:+:~":""''"'"'''''''"''"'+"'"""'""""'"'"''"'"""""""""'"''""''''""''"'"""''"''"''"''"'"''""'""""'""''""'""''"''"''""""''"

.••.. ··· .. ············•• <'·.- 0.9 F-H,':"-"···:·"''"'-'"•Hf·•+f:'i·H·H·•i·i ........................................... , .......................................................................... . [)(4 ... > { ··.· -"· 0.03

1•-"c::~~--..;.., ..... , .... ,., ... :'"''~'"~"''''"'"'~'+-....................................... , ......................................................................... ..

:t•·.··· ................ ••••••••••• - 43 000 b .. ,-~-;-"~~;-;-·~~,. ...... --.-,~··--.. ~, ..... •+-....................................... , .......................................................................... .

···•··••••• > •••······.····· -"· 1.6 ''"l'•··r"''"", .·.·.·''"," ••".·'"•' ··'".·······_ ..... , ....... ,, .................. ·-;-_ .... _ ...................................... , ............................... 34_8 .............................. . ''"'""''•''"'+''·'··•-'""'""'"'·-·'··'··'···'·'"''"+"'"""'"''""'"'""'"'"'"""''"'"'"'"'"'"'"'"'"''"''"""""'"'"'""'"""""'"""''"''"''"''"'""'"'"''"'-"""'

·•••·••· •·•·••·•••••··••···. ·············- 0.6 "'"""'''"'""'"''""''"''"'""''"'"""'"'''"''''~"'"''""'""'""""""""'"""'"""""''t"'""'"'""'"'"'""'"''"''"'"'""'"'"''"'""'"''""'"''""'"'""'""'"""

u ··••·. < ..... ············- 0.04 l"c;,'"t§!~i]Ji[ZJJiJI:il~:~~~::::~:~:~:::~:~:~::::t .......................................................................... . t~~ . .. ••••• . ..• - ............................. Q:Q.?. ............................ .. H'""'''~'""'' .. ·"''"')"""'cc.;,,;c;:." ••,. •_···'" '',•c ···H····.-..... ·" ... · ................................... , ............................. ~.! .. ~2... ........................ ..

l"" .'·•·. < ··········•······· TU 0.8 ""'""r("' ,.~f ........ F ................. L •• "'"'<"""'·"·i· .. Jl .... g/L ...................................... , ........................... o:·os4 .......................... . b·:'~3"4l/UE23liT·"H······-·r-·l<.' .................................. t .......................................................................... . IU• 1.27 t--···"'"'"""'"'""'""''"""''"''"'""''~''"'1·-·"''""'"'"'"""'"""'""''"'""''""'"''l"''"'"'"'""''"""""""""'"'"'"''"""''"'""''"""'"'""'"'""'"'

'F, •·•••···•·. •······· ...•.• Bq/L ................................. 4.?. ............................... .. .( '·>· ,. •. • > ••·•••• .. . •.•. pM ................................. ~?. ................................ . ~~ .•...• > < . .. rnVL ............................... 4.?..9 ............................. .. c ··.·· ....... .. .... .. .... .. .. - ............................. 9..:.9.?. ............................ ..

I ' .. •·····' •••••• <'············- ............................... ~.§ .. ?. .............................. . lJ •• . .•• ( ... ···•• .• ··• . '.·' _... . .............................. ?..?.9. ............................ ..

['] ~····•• ······) .,·•••· mg/L 70 000 *) uncertain values due to analytical problems.

Finnish reference waters for solubility, sorption and diffusion studies

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