SAFETY ASSESMENT APPROACH FOR DEEP GEOLOGICAL REPOSITORY IN CZECH REPUBLIC Václava Havlová, Dagmar Trpkošová, Eva Hofmanová (ÚJV), Antonín Vokál (SURAO) ÚJV Řež, a. s. 24.11.2016 International Conference on the Safety of Radioactive Waste Management, IAEA, Vienna
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SAFETY ASSESMENT APPROACH FOR
DEEP GEOLOGICAL REPOSITORY
IN CZECH REPUBLIC
Václava Havlová, Dagmar Trpkošová,
Eva Hofmanová (ÚJV), Antonín Vokál (SURAO) ÚJV Řež, a. s.
24.11.2016
International Conference on the Safety of
Radioactive Waste Management, IAEA, Vienna
Content
Czech SNF and HLW disposal concept
Safety assessment (SA)
SA model components
Container
Corrosion research
Bentonite
Radionuclide migration in bentonite
Geosphere
Laboratory studies on RN migration in host rock
In-situ studis on RN migration in host rock
Biosphere
Conclusions
Czech SNF disposal concept
2
Based on Svedish KBS-3 concept
Reference project (2011)
horizontal disposal
spent nuclear fuel
carbon steel container
local Ca-Mg bentonite
granitic host rock
-
HLW disposal concept
Waste from NPP decommissioning
Activated NPP metalic parts
Concrete
Vitrified waste from research reactor
Institutional waste
Radiation sources
3
n)m)
Potential sites for DGR siting in Czech republic
7 candidate sites
Čertovka
Granitoidy tiského plutonu
Kraví hora
Strážecké moldanubikum
Svratecké krystalinikum
Horka
Strážecké moldanubikum
Granitoidy třebíčského plutonu
Hrádek
Moldanubický plutonický komplex
Čihadlo
Monotónní skupina moldanubika
Granitoidy klenovského plutonu
Magdaléna
Monotónní skupina moldanubika
Pestrá skupina moldanubika
Středočeský plutonický komplex
Březový potok
Pestrá skupina moldanubika
Středočeský plutonický komplex
Safety assessment (SA)
Safety assesssment (SA) is the key tool to prove that repository components fulfill
their safety function
DGR long term safety has to be proved to Regulator (SONS) in order to obtain a
licence for siting
one of the main requirements (Decree No. 307/2002 Coll.):
to provide a protection to man and environment in such a way that effective dose of
0,25 mSv per year for a member from critical group of inhabitant with all considered risk in
operational and post-operational phase
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
1000 10000 100000 1000000
čas [y]
dáv
ka [
mS
v.y-
1] A G1
A G2
A G3
A G4
limit
Effective dose, obtained by the individual from the critical group od
inhabbitants. Normal scenario development (container with
mininimum 50 000 year life time, median 110 000 y, Weibull
distribution). Reference project 2011.
SNF activity decrease. Time interval
determination for safety assessment 100 000 years
Safety assesment calculations:
Goldsim environment
Safety assesssment is the key tool to prove that repository
components fulfill their safety function
CZ: Goldsim programme based model has been
developed since 2004
SA MODEL: CONTAINER
Disposal of 6 000 carbon steel SNF container
Activity release after degradation of SNF
container.
SNF container degradation: described by
distribution curve obtained by applying the
Weibull distribution.
Minimum container life-time: 10,000 years
median:110,000 years.
The model assumes average inventory.
Corrosion rate and corrosion progress determination
8
Carbon steel sample in contact with Ca-Mg
bentonite
Installed ÚJV/SURAO MACOTE
corrosion modules, Grimsel test site
(CH)
Research and development of disposal
canister for SNF deep geological disposal.
SÚRAO project (2013 - 2017).
http://www.grimsel.com/gts-phase-vi/macote-
the-material-corrosion-test/macote-
introduction
SA MODEL: BENTONITE
Bentonite layer is modeled by fifteen concentric layers.
The outer layer represents the interface with the repository surrounding (rock compartment).
The rock diffusion layer is modeled at the interface bentonite/ rock compartment in order to eliminate the influence of advection in bentonite layer.
The radionuclides are transported by diffusion through the bentonite layer towards a rock compartment (model view only). The rock diffusion layer is modeled at the interface bentonite/ rock compartment in order to eliminate the influence of advection in bentonite layer.
Rock massive is modeled as a compartment of 3km 1km 10 m size. At each time step, the concentration balance is set in this area, it means that the same conditions are valid in the whole area.
RN are transported by the groundwater flow (advection is considered as a transport process) to a preferential path in the geosphere.
Posiva Oy, 2012)
SA MODEL: GEOSPHERE
components "Pipes" (more than one), considering the model
transport processes as an advection, diffusion into the rock matrix
and sorption.
groundwater flows from the last "Pipe" into the compartment,
which model the processes in biosphere.
geosphere_deep_pathway
geosphere_shallow_pathway
geosphere_midle_pathway
depository_closed_area
M2+
M2+
M 2+
M2+
M 2+
M2+
CO32- M2+
CO32-
M2+
coll
Aqueous
complexationM2+
M2+
coll
coll
Sorption
Colloid
formation
Precipitation
of pure phases
CO32-
CO32-
M2+
M2+
M2+
M2+
M2+
M2+
M2+
M2+
M2+
M2+ M2+
M2+
M2+
Co-precipitation
Solid solutions
M2+ Radionuclides
M2+ Other cations
CO32- Anions
coll Colloids
•D. Arcos,_Amphos
Host rock: site specific samples
13
potential sites (Čertovka, Horka, Hrádek,
Březový potok, URL Bukov (Kraví hora), Čihadlo
Grimsel test site (CH)
Sweden (Oskarshamn, Forsmark)
Rock samples from Hradek, Horka and Čertovka were obtained under MPO FR TI1/367 project
Horka Hrádek Čertovka Bukov
Čihadlo
24.
11.
201
6 14
Radionuclide migration in granite:
sorption and diffusion (Kd, De)
Diffusion cells for granite
HTO,, 36Cl, 131I, 99Tc, 75Se, 134Cs. 22Na, 85Sr
0.00
0.03
0.06
0.09
0.12
0 1 2 3 4
c/c 0
days
3-H
36-Cl
Se(VI)
99-Tc
125-I
Anion diffusion anions through Aare
granite
(LTD Phase III., project, E. Hofmanová)
Anaerobic sorption of Se(IV) on Aspo
diorite; Videnská, 2013;
CROCK EU FP7 project
Steps toward real host rock conditions
URL Josef
• testing of in-situ
methodologies
Grimsel Test site
• Long term diffusion
(LTD) experiment
Ruprechtov natural
analogue site (W Bohemia)
• observation of
U migration in clay
In-situ transport parameter determination
16
Circulation
borehole
Observation
borehole
Observation
intervalDiffusion
interval
H-3 (HTO) diffusion
plume after 2 years
Circulation interval (Kontar, 2011):l = 72 cmr = 2.8 cm
Total vol. solution: ca. 3 L
Fracture model in PAMIRE project -
preliminary results Josef URL
PAMIRE - http://www.ujv.cz/cz/pamire.
TA04020986
LTD Phase III. experiment concept. Figure
NAGRA
Long term diffusion Phase VI. project -
http://www.grimsel.com/gts-phase-vi/ltd/ltd-
introduction
PAMIRE project:
HTO injection presumed in the
rock fractures system
URL Josef
Long term diffusion III. Phase VI.
project
3H, 22Na, 133Ba, 134Cs and
non-active Se(VI);
Grimsel test site (CH)
SA MODEL: BIOSPHERE
4 compartments - a universal model according to the current lifestyle of the Czech Republic
land
cultivable
forest
pond
river
The output of the biosphere model is the effective dose rate to humans living in the area affected by DGR.
People living in this area consume only products of farming and do not import any food and beverages
Conclusions
model improvement: the source term, the refinement of
the geosphere transport model, the construction of
individual biosphere models for each DGR candidate site,
uncertainty evaluations etc.
the model is planned to be completed in 2018 which will
address in greater detail one of the potential sites for the
construction of the Czech DGR
R&D is inevitable for SA calculations;
data input cannot be solitaire
feedback from SA is needed
18
Acknowledgement
The Goldsim model development was funded by
Ministry of Trade and Industry (MPO TIP FR TI1/362) and