Safe management of Low and Intermediate Level Waste (LILW) … Documents... · 2013. 12. 3. · Drinking water treatment waste Sludges - ~600 (only Ra reported) Resins - ~1,300,000

IAEA International Atomic Energy Agency

name of presenter (e-mail)

training event title

dates

location, host organization, host country

Safe management of Low and Intermediate

Level Waste (LILW) prior to Disposal

http://www.facebook.com/photo.php?pid=39861&id=1732371649

IAEA

Contents – Part 1

• Introduction and review

• Sources of LILW

• Review of Options

• Segregation, minimisation and characterization

• Development of waste form and associated safety considerations

2

IAEA

Key references

3

2009 2003 2005 2008

IAEA

Introduction

• Importance of safe management of radioactive waste has long been

recognized;

• Fundamentals and higher-level requirements for predisposal waste

management;

• This module addresses specific guidance for predisposal management of LILW.

4

IAEA

Predisposal Management (Review)

• Predisposal includes all steps from waste

generation to final

acceptance for

disposal or removal

from regulatory

control;

• Class review: provide examples of the steps

in the waste

management lifecycle.

5

IAEA

Facility Design

• Measures are needed to avoid or reduce, to the extent practicable, generation of

radioactive waste requiring long-term

controls

• Segregation and release;

• Reuse or recycle;

• Manage in accordance with national strategy.

6

IAEA

LILW Sources

• Nuclear Fuel Cycle Operations

• Research and Development Facilities

• Decommissioning of Facilities and Remediation

• Sealed Sources

• NORM

• Small Users

7

IAEA

Types of LILW

• Short-lived and long-lived;

• Solid, liquid, or gas;

• Surface contaminated or activated materials;

• Concentrated with higher activity or large volumes at lower activities.

8

IAEA

Gaseous Waste

• Effluents from ventilation systems;

• Off-gas from systems for primary coolant

degasification in

reactors;

• Off-gas from processing systems (e.g., spent

fuel);

• Off-gas from storage tanks.

9

IAEA

Liquids

• Laundry and shower water;

• Drainage from floors and equipment;

• Organic liquids;

• Decontamination liquids (may include complexing

agents);

• Chemical process residues;

• Produced water from oil wells.

10

IAEA

Slurries

• Spent ion exchange resins;

• Filter aids;

• Sludges;

• Precipitation flocculants;

• Evaporator concentrates;

• Scale removed from oil wells;

• Petroleum or other tank bottoms.

11

IAEA

Solid Waste

• General contaminated trash, incinerator residues;

• Metallic components and tools;

• Fuel cladding and assemblies;

• Protective equipment; • Filter boxes; • Debris; • Activated components; • Radiation sources; • NORM.

12

IAEA

Generators (Nuclear Fuel Supply)

• Refining and conversion of U and Th;

• Enrichment;

• Fabrication;

• Examples of wastes include: contaminated solids, process sludges, aqueous and organic liquids (long-lived alpha emitters).

13

IAEA

Generators (Nuclear Power Plant)

• Primarily short-lived contaminated and activated materials, but some long-lived

fission and activation products;

• Solid, liquid and gaseous waste;

• Class discussion – examples of different wastes from nuclear power plants.

14

IAEA

Reactor Operations

15

IAEA

Activity Levels in LILW from Reactors

16

IAEA

Examples of “Mixed” LILW

Chemotoxic Waste Stream Radionuclides present

Used liquid scintillation fluids H-3, C-14

Waste oil H-3, C-14, Mn-54, Co-60, Zn-65, Cs-134, Cs-137

Chlorinated organics H-3, C-14, P-32, S-35, I-125

Lead wastes P-32, Co-60, I-125, Cs-137

Mercury wastes H-3, C-14, I-125

Chromium wastes Cr-51, Co-60

Cadmium wastes Co-60, Cs-134, Cs-137

Aqueous corrosive liquids H-3, C-14, Co-60, Cs-137

17

IAEA

Generators

(Decommissioning and Restoration)

• Typically large volume, less contaminated wastes (debris, soils, etc.);

• Some reactor components can involve higher activity levels and long-lived radionuclides;

• Liquid wastes may also be generated from cleaning and decontamination operations.

18

IAEA

Spent-Fuel Management

• Spent fuel may be managed intact or processed;

• Reprocessing is a source of short- and long-lived solid,

liquid, and gaseous waste,

for example:

Fuel cladding and fuel

assembly components;

Sludges and concentrates

from effluent treatment;

Gaseous waste during fuel

dissolution.

19

IAEA

Generators (Research and Pilot Plants)

• Wide variety of process specific wastes, no

general description:

Research Reactors;

Hot Cells;

Pilot fuel processing;

Maintenance facilities;

Post-irradiation

examination facilities;

R&D and laboratory

facilities.

20

IAEA

LILW in Many Countries

• Mining and Mineral Processing;

• Spent Sources;

• NORM

• Oil and Gas;

• Industry;

• Hospitals.

21

IAEA

NORM Facilities

• Oil and Gas;

• Phosphogypsum;

• Geothermal;

• Drinking water treatment;

• Mining and mineral processing.

22

IAEA

Oil and Gas NORM

Ethane (Rn + d)

Propane (Rn + d)

Butane

Plant Fuel

To StorageChiller

Gas Plant

Ab

so

rbe

r

Tre

ate

r

Residual or

Sales Gas (Rn + D)

Flare

Rn + d

Gas Plants

Flare

Rn + d

LNG

Rn + d

Sales

Gas Compressor

Stations

Well

Head

Gas

Rn + d

Rn + d GasGas Rn + d

Stock

TanksPipe Line

Many Days

He

ate

r

Tre

ate

r

Se

pa

rato

r CrudeH O2 Crude

U + ThU + Ra

+ Th

Ra + d

Th + d

Water

Treatment

Plant

Injection

or Discharge

Ra +d, Th + d

Well

Head

U + Ra +

Rn + d +

Th + d

Crude

Gas

H O2

23

IAEA

Radioactivity in NORM

These data should only be used as rough indicators of the levels of radioactivity.

Material Radionuclide Concentrations (Bq/kg)

Scale in pipes and equipment for oil/gas production 0 - 15,000,000 (average one thousand to

hundreds of thousand)

Sludges in natural gas supply equipment up to ~40,000

Sludges from ponds of produced water 10,000 to greater than 40,000

Scales from geothermal energy production 4,000 - 40,000

Uranium mining overburden 100 - 20,000 (only Radium reported) (average

~5,000 total radionuclide concentration)

Coal fired power plants 100 - 25,000

Drinking water treatment waste Sludges - ~600 (only Ra reported)

Resins - ~1,300,000 (only Ra reported)

Phosphate fertilizer 1,000 - 25,000

Phosphate processing waste Phosphogypsum - 1,000 - 4,000

Slag - 2,000 - 7,000

Scale - ~40,000 (only Ra reported)

Other mineral processing waste up to 40,000 (generally 100 - 5,000)

226

226

226

24

IAEA

Processing Options (Review)

• Pretreatment;

• Treatment;

• Conditioning;

• Container or Packaging;

• Storage.

25

IAEA

Waste Disposal Options

Surface Disposal

Surface Discharge Geological Disposal

Well injection

Near-Surface Disposal

26

IAEA

Waste Acceptance Criteria

• Predisposal management is intended to produce waste that can be handled, transported, stored and disposed safely;

• Acceptance requirements for each step considered early and met;

• Conditioning requirements for disposal generally the primary consideration;

• Quality assurance programs are critical.

27

IAEA

Other Hazards

• Toxic metals;

• Explosive or fire risks;

• Biotoxins;

• Organics.

28

IAEA

Control of Waste Generation

• The best waste management approach is to limit the generation of the waste at the source (waste minimization);

• Minimization applies to the volume and activity of waste;

• Primary waste generation as well as secondary wastes from predisposal activities;

• Discussion: waste minimization approaches.

29

IAEA

Waste Minimization Strategies

• Segregation and use of controlled areas;

• Proper planning and selection of equipment;

• Decontamination, when possible, and awareness of secondary waste from

decontamination;

• Recycle and reuse.

30

IAEA

Effectiveness of Minimization

0

100

200

300

400

500

600

Cu

bic

Mete

rs D

isp

osed

per

Reacto

r U

nit

Volume of LILW Radioactive Waste Disposed

(Median Values for PWR)

Volume of LILW Radioactive Waste Disposed

(Median Values for BWR)

0

200

400

600

800

1000

198

0

198

2

198

4

198

6

198

8

199

0

199

2

199

4

199

6

199

7Cu

bic

Mete

rs D

ispo

sed

per

Re

ac

tor U

nit

USA

France

31

IAEA

Reduction at Source

• Design (materials, processes, structures) considering waste minimization;

• Design considering decommissioning needs;

• Techniques and equipment that do not result in excess waste generation;

• Effective containment and packaging of radioactive materials;

• Zoning to limit areas of contamination.

32

IAEA

Discharge, Recycle/Reuse Example

Uranium extraction from ore

33

IAEA

Considerations for Choice of

Preferred Options

• Waste characteristics;

• Acceptance criteria at receiving facilities;

• Availability of facilities;

• Availability of processing;

• Regulations for use, discharge, and removal from control.

34

IAEA

Planning and Design for Decommissioning

• Account for radionuclides in residual waste, technical

implementability, cost,

schedule, and institutional

factors;

• Initial and final decommissioning plans;

• Specification of critical tasks;

• Identification of management functions;

• Commensurate with level of hazards.

35

IAEA

Development of LILW Waste Form

36

IAEA

LILW form development

• Waste form that meets acceptance criteria at all stages including disposal;

• Ideally maximize the amount of waste that is suitable for discharge, use, or

removal from regulatory control;

• Licence requirements strictly observed and changes should be reported to the

regulatory body.

37

IAEA

Waste Characterization

• Characterization may occur multiple times during pretreatment for information on properties, to confirm for acceptance, process verification, etc.;

• Requirements will depend on waste type;

• Sampling and analysis, process knowledge, and/or nondestructive or destructive testing.

38

IAEA

Waste Form Specifications

• Specifications are necessary to ensure that the final waste form satisfies

acceptance criteria;

• Radiological characteristics are determined early in the process;

• Other characteristics that can be quantified into specifications are

introduced on the following slides.

39

IAEA

Chemical and Physical Properties

(Waste Form)

• Chemical composition;

• Physical properties (density, permeability, etc.);

• Homogeneity, waste compatibility;

• Thermal stability;

• Moisture percentage;

• Leachability and corrosion rates (used for source term release modeling).

40

IAEA

Mechanical Properties

• Tensile and compressive strength;

• Dimensional stability;

• Behavior under expected mechanical or thermal loads;

• Expected changes in properties for time frame over which mechanical

stability is needed.

41

IAEA

Chemical and Physical Properties

(Container)

• Container materials;

• Physical properties (permeability, etc.);

• Thermal conductivity;

• Degradation rate in disposal environment;

• Corrosion rate in disposal environment.

42

IAEA

Physical Properties of Waste Package

• Acceptable void percentage in container;

• Effectiveness of seals for gas and moisture;

• Presence of any vents, if gas generation is expected;

• Sensitivity to changes in temperature.

43

IAEA

Containment Capability

• Long-term performance as a barrier to radionuclide

releases;

• Diffusion and leach rates in disposal environment;

• Gas release rates, including tritium;

• Fixation and retention of radionuclides;

• Seal capability (moisture, gas).

44

IAEA

Waste Package Stability

• Temperature cycling;

• Elevated temperatures (e.g., fire);

• Radiation damage;

• Moisture resistance;

• Corrosion resistance (including micro-organisms);

• Gas tightness and potential for pressurization.

45

IAEA

Contents – Part 2

• Pretreatment

• Treatment

• Conditioning

• Storage

• Record Keeping

46

IAEA

Pretreatment

• Includes collection, segregation, chemical adjustment, and

decontamination;

• First priority to reduce amount of waste;

• Second priority to adjust characteristics to make amenable for further processing

or reduce hazards.

47

IAEA

Pretreatment – Collection/Segregation

• First step is to collect and segregate waste,

characterization is critical at

this point;

• Waste that can be discharged or for which

regulatory controls can be

removed (clearance, recycle,

store for decay, etc.);

• Low activity, short-lived and long-lived LILW segregated.

48

IAEA

Characterization During Pretreatment

• Proper characterization is essential to ensure proper

segregation and

management of waste (basis

for initial documentation);

• Radiological, chemical, physical, and pathogenic

properties;

• Potential hazards should be identified (incompatibilities,

gas generation, etc.).

49

IAEA

Pretreatment – Segregation for Treatment

• Segregation should also be based on the overall waste management strategy and

available facilities, for example:

Combustible or non-combustible

(incineration);

Compressible or non-compressible

(compaction);

Metallic or non-metallic (melting or sizing);

Fixed or non-fixed surface contamination

(decontamination).

50

IAEA

Liquid Waste Segregation

It should be based on their properties: Activity and radionuclide content

Short-lived radionuclides suitable for decay storage

Long-lived liquid waste requiring conditioning, subsequent storage and final disposal

Organic liquids

Aqueous liquids

Non-homogeneous waste (sludge)

Infectious liquids

Chemically hazardous liquids

51

IAEA

Segregation of Solid Waste

Activity and radionuclide content suitable for decay

Pathogenic

Toxic (heavy metals, cyanide, etc.)

Dangerous (explosive, pyrophoric, etc.)

Sharp (broken glass, hypodermic needles, etc.)

Damp solids

Presence of absorbed liquid waste (flash points >60oC)

Combustible/non-combustible

Compactable/non-compactable

52

IAEA

Segregation of Solid Waste

(for sending to centralized facility)

Solid waste sent to a centralized facility for compaction should not contain the following kind of waste: Sealed sources

Absorbed liquids (unless in an approved form);

Flasks containing free liquids

Heavy objects;

Wood (in some cases);

Uncontained (loose) sharp;

Toxic, pathogenic and dangerous materials;

Powders;

Aerosol or pressurised containers.

53

IAEA

Segregation of Solid Waste (Container)

• Storage containers should be appropriately labelled with a radiation trefoil and a unique identification code.

• The following information on the waste should be retained:

Identification number

Radionuclides

Activity (if measured or estimated)/date

Origin (room, laboratory, installation, etc. if applicable)

Potential/actual hazards (chemical, infectious, etc.)

Surface dose rate/date of measurement

Quantity (weight or volume)

54

IAEA

Pretreatment – Decontamination

• Decontamination removes surface contamination via mechanical, chemical and electrochemical methods;

• LILW may be suitable for release from regulatory control;

• Generation of secondary waste and the characteristics of secondary waste.

55

IAEA

Pretreatment – Mixing

• Mixing of waste must be limited to compatible waste forms, unless

hazards are mitigated (chemical

reactions, volatilization, etc.);

• Organic liquids should be segregated due to chemical nature

and specific hazards.

56

IAEA

Removal from Regulatory Control (1)

• Authorized discharge, disposal, recycle, reuse, and direct removal from regulatory control;

• Decontamination or store for decay;

• Specific exemption criteria identified in GSR Part 3;

• Formal process established to demonstrate regulatory compliance (radiological and non-radiological).

57

IAEA

Removal from Regulatory Control (2)

• Authorized atmospheric and liquid discharges part of an optimized waste

management programme;

• Buildings and sites may also be removed from regulatory control after all waste is

properly managed and decontamination.

58

IAEA

Treatment of LILW

• Volume Reduction (e.g., incineration, compaction, or sizing);

• Removal of Radionuclides (e.g., evaporation, ion exchange, filtration);

• Change of Form (e.g., precipitation, digestion, oxidation);

• Change of Properties (e.g., melting).

59

IAEA

Treatment – Combustion (1)

• Greatest volume reduction for combustible waste (liquid or

solid, effective for organics);

• Radionuclides in ash, exhaust gas cleaning residues, and

discharges;

• Corrosive combustion products should be identified and

limited;

• Accumulation of radionuclides in gas cleaning residues and

ash;

60

IAEA

Treatment – Combustion (2)

• Stack emissions are a consequence of combustion;

• Monitoring of stack emissions provides evidence that authorized limits are not exceeded;

• Off-gas scrubbing may be implemented to control emissions;

• Non-radiological emissions must also be considered (e.g., acids, PCBs, etc.).

61

IAEA

Treatment – Compaction (1)

• Many LILW streams are amenable to compaction

(e.g., general trash,

protective clothing, etc.);

• Acceptance criteria for the compaction facility should be

well defined;

• Desired volume reduction for different types of waste

should be defined;

62

IAEA

Treatment – Compaction (2)

• Potential consequences must be considered when

designing and operating a

compactor:

Airborne and liquid

releases;

Chemical reactivity during

and after compaction;

Fire or explosion resulting

from pyrophoric or

explosive materials or

pressurized components.

63

IAEA

Treatment - Sizing

• Large bulky items may be segmented, disassembled, or sized by other means;

• High temperature flames, sawing methods, hydraulic shearing, abrasive cutting, and plasma arc cutting are possible methods;

• Particulate contamination should be a major consideration when selecting an approach and during operations.

64

IAEA

Treatment – Radionuclide Removal (1)

• Aqueous and gaseous wastes are often amenable to treatment approaches that remove radionuclides and organics, for example: Evaporation;

Ion Exchange;

Filtration, Ultrafiltration;

Centrifugation.

65

IAEA

Treatment – Radionuclide Removal (2)

• Concentrating a gaseous or liquid waste stream can lead to the potential for criticality

or creating a concentrated waste stream that

does not meet acceptance criteria;

• Process designed such that any liquids remaining after radionuclide removal are

suitable for discharge or treatment.

66

IAEA

Radionuclide Removal – Ion Exchange

• Ion exchange is a proven method commonly implemented to remove

radionuclides from a liquid waste stream;

• Spent resins managed as a liquid slurry or as a solid waste;

• Gas generation and other potential radiolytic or chemical reactions need to

considered, if prolonged storage.

67

IAEA

Radionuclide Removal – Filtration (1)

• Filtration is also an often used and proven method for radionuclide removal;

• Particulates and aerosols in gases may be removed using HEPA filters;

• Iodine and noble gases can be removed by filters or sorption beds with activated charcoal;

• Filters are also effective for some liquid waste streams;

68

IAEA

Radionuclide Removal – Filtration (2)

• Regulatory body may require redundant filters;

• Pre-filters or roughing filters, temperature and humidity controls, and monitoring equipment;

• Used filters and sorption beds are managed as solid waste ;

• Concentrations of radionuclides should not be allowed to exceed levels accepted for future

conditioning, storage or disposal.

69

IAEA

Filtration Example

(membrane reverse osmosis)

• Nine Mile Point (BWR) operates under “zero liquid” discharge approach;

• Process water: reactor shroud swarf, sanitary water, lake water, and oily wastewater;

• Reduced secondary waste generation by 89% compared to demineralizer;

• High water purity, low organic content;

• Solid wastes in concentrate consistently Class A LLW (US NRC) after dehydration

70

IAEA

Treatment – Change of Form (1)

• Aqueous wastes are also amenable to treatment approaches that change the

form of the waste or radionuclides, for

example:

Chemical Precipitation;

Digestion;

Oxidation.

71

IAEA

Treatment – Change of Form (2)

• When changing the form of a waste or radionuclides in a waste, process limitations need to be

considered, for example:

Corrosion;

Scaling or Foaming;

Fire or explosion risk in presence of organics;

• Safety issues (criticality, highly concentrated radionuclides in secondary waste) associated with

remove radionuclides are also relevant in this case.

72

IAEA

Treatment – Change of Properties

• Non-compressible and non-combustible solid waste may be treated by change of properties;

• Melting LILW metal waste is one example;

• Melting can homogenize radionuclides in a slag, which may lead to beneficial averaging of concentrations.

73

IAEA

Conditioning

• Operations that produce a waste form and package suitable for:

Safe handling;

Transport;

Storage; and

Disposal;

• Immobilization of liquid or dispersable waste, container, and/or overpack, as necessary.

74

IAEA

Conditioning – Waste Form (1)

• Liquid or slurried LILW often converted to solid form (e.g., cement) that should have following characteristics, as necessary:

Compatibility waste form and container;

Homogeneity;

Low void space;

Low permeability and leachability;

Stability for time period required;

Resistance to chemical and biological attack;

75

IAEA

Conditioning – Waste Form (2)

• Certain metals may react with alkaline water in a cement slurry

to produce hydrogen;

• Chelating agents and their potential impact on the

solidification process;

• Solid waste generally exhibits same characteristics listed on

previous slide, but homogeneity

and void space may not apply .

76

IAEA

Conditioning – Waste Packages (1)

• End goal is that the package resulting from conditioning should meet respective

acceptance criteria, as applicable;

• Regulatory body and operators for transport, storage and disposal should be

consulted to confirm criteria can be met;

77

IAEA

Conditioning – Waste Packages (2)

• Waste and container should be compatible for time frame

required;

• Container may need to provide shielding depending

on waste form and methods

selected for handling,

transport, and storage;

• Potential need for decontamination of container

should be considered;

78

IAEA

Conditioning – Waste Packages (3)

• Container should be designed to maintain integrity for all steps in

process;

• Long-term integrity must allow for

• Retrieval at end of storage;

• Enclosure in overpack, if necessary;

• Transport and handling at disposal facility;

• Long-term performance after disposal.

79

IAEA

Examples of Waste Packages

80

IAEA

Container Labeling

• Unique container identifier;

• Radiation levels;

• Handling requirements;

• Weight;

• Description of contents;

• Special hazards.

81

IAEA

LILW Storage Considerations

• Short-lived LILW is often collected and stored for a time sufficient to meet

regulatory requirements for release, use,

or discharge;

• Strict acceptance criteria and container integrity requirements for waste

potentially stored for long periods of time

awaiting a disposal facility.

82

IAEA

LILW Predisposal Records (1)

• Records relate to the facility, the waste and compliance

with acceptance criteria,

including:

data for national inventory of

waste;

data for waste characterization;

records for control processes

during predisposal;

container procurement records;

83

IAEA

LILW Predisposal Records (2)

• Waste package specifications;

• Audit records for waste packages;

• Operating performance trends;

• Non-compliances with specifications and corrective actions;

• Monitoring, surveillance and inspection records;

• Safety assessment documentation;

• Operating procedures;

• Other data as required by Regulatory Body.

84

IAEA

Waste Characterization Record Keeping

• Characterization records form the basis for many management decisions throughout life cycle for a waste;

• Updated as a result of predisposal activities;

• Serve as key input for decisions regarding compliance with acceptance criteria.

85

IAEA

Waste Characterization Records

The following information should be maintained in a characterization record:

Source or origin;

Physical and chemical form;

Amount;

Radiological characteristics;

Classification;

Non-radioactive hazards;

Special handling requirements.

86

IAEA

Predisposal Reporting Requirements

• Periodic reporting to the Regulatory Body is necessary

to verify compliance with

regulatory authorizations;

• Routine reports address operations during reporting

period and status at end of

period;

• Any incident or accident or variation from the safety basis

should be reported promptly.

87

IAEA

Predisposal Report Summary (1)

A periodic report from a predisposal waste

management facility should generally

contain a summary of:

Waste received, including secondary waste

generated at the facility;

Waste processing;

Waste transfers;

Effluent discharges;

88

IAEA

Predisposal Report Summary (2)

• Material removed from regulatory control;

• Inventories and net changes waste received, processed, stored, transferred;

trends in safety performance;

• Estimate of radiological impacts;

• Non-compliances.

89

IAEA

Summary

• Main goal is to minimize generation of waste

• Characterization is critical throughout predisposal

• Variety of approaches are available for treatment and conditioning

• Efforts on characterization can be wasted with improper labeling and

recordkeeping

90

IAEA Thank you! 91