IAEA Activities Related to Clearance and Exemption

Transcription

1 Eleventh Annual Meeting of the International Decommissioning Network (IDN) 5-7 December 2017 IAEA, Vienna, Austria IAEA Activities Related to Clearance and Exemption Vladan Ljubenov International Atomic Energy Agency Division of Radiation, Transport and Waste Safety

2 Introduction PRIS Shutdown scenario (assumption of 40 years life time for operating reactors) Power Reactors with an established final shutdown timeframe Power Reactors with no established final shutdown timeframe Scenario 40yrs 50yrs OTHERS NR yrs Power reactors still in operation scenario 40yrs PWR + BWR

3 Introduction Decommissioning typically generates large amounts of material (potential to be recycled and reused) and waste (no intention for reuse). Those amounts are larger than during operation and are generated in a relatively short period of time (several years). Most of that material and waste is expected to be radiologically clean or just slightly contaminated. It could be practical and economically viable to separate the part that has to be managed as radioactive waste or reused within the nuclear applications (under continual regulatory control), and the part that can be taken out of the regulatory control (through clearance) immediately, after decontamination or after a decay.

4 Growing importance of clearance Increasing number of Member States requests for assistance in establishing provisions for clearance and in implementing clearance Existing guidance in the IAEA Safety Standards (RS-G-1.7) and in supporting publications does not satisfy needs of Member States Related IAEA activities are presented

5 Concepts of Exclusion, Exemption and Clearance Exclusion, exemption and clearance define the scope of regulatory control as it applies to planned exposure situations. Application of the Concepts of Exclusion, Exemption and Clearance (RS-G- 1.7, 2004) Exclusion - The deliberate exclusion of a particular category of exposure from the scope of an instrument of regulatory control on the grounds that it is not considered amenable to control through the regulatory instrument in question. Exemption - The determination by a regulatory body that a source or practice need not be subject to some or all aspects of regulatory control on the basis that the exposure and the potential exposure due to the source or practice are too small to warrant the application of those aspects or that this is the optimum option for protection irrespective of the actual level of the doses or risks. Clearance - The removal of regulatory control by the regulatory body from radioactive material or radioactive objects within notified or authorized practices.

6 Options for control of radioactive material Exclusion Authorized Discharge Radioactive Material Regulatory Control Authorized Disposal Exemption Clearance

7 Exemption vs. Clearance

8 Relevant IAEA publications

9 Clearance / Exemption GSR Part 3 (BSS) Requirement 8: Exemption and clearance The government or the regulatory body shall determine which practices or sources within practices are to be exempted from some or all of the requirements of these Standards. The regulatory body shall approve which sources, including materials and objects, within notified practices or authorized practices may be cleared from regulatory control. Similar dose and risk criteria applied for both exemption and clearance.

10 Criteria for clearance (BSS Schedule I) I.10. The general criteria for clearance are that: a) Radiation risks arising from the cleared material are sufficiently low as not to warrant regulatory control, and there is no appreciable likelihood of occurrence for scenarios that could lead to a failure to meet the general criterion for clearance; or b) Continued regulatory control of the material would yield no net benefit, in that no reasonable control measures would achieve a worthwhile return in terms of reduction of individual doses or reduction of health risks.

11 Criteria for clearance (BSS Schedule I) Clearance of material without further consideration if in reasonably foreseeable circumstances, effective dose for any individual from this material on the order of 10 µsv or less in a year and for low probability scenarios 1 msv in a year Clearance levels (CL) in the BSS: Table 1.2 for any quantity of solid material identical to exemption values for bulk amounts of solid material

12 Derivation of clearance and exemption levels Clearance levels in the IAEA-BSS Determined that the cleared material may be used without any further restrictions Based on IAEA SRS-44 IAEA-BSS Footnote 65 specific clearance levels may be developed for metals, rubble from buildings and waste for disposal in landfill sites: Conditional clearance levels

13 Interdependence of clearance and exemption levels The concepts of clearance and exemption are different in nature Clearance levels are derived based on different assumptions / different purpose than exemption levels Using only one set of values for both concepts is not necessary in principle, but there are also advantages of having a single set of values If values are different, take the lower one in some cases unnecessary conservativism Clearance levels shall not be higher than exemption levels

14 Current guidance in RS-G-1.7 Provides mass specific values that can be used for exemption or clearance (unconditional), as appropriate, of bulk quantities of solid material. Values are provided for both natural and artificial radionuclides. The models used in the calculations of individual dose are described in SRS-44. Those scenarios are primarily relevant for clearance, since these were found to be the most restrictive. These values for exemption and clearance of bulk amounts of material now appear in GSR Part 3, together with the values for exemption of moderate amounts of material from SS-115. Regarding natural radionuclides, the values set out in RS-G-1.7 were selected on the basis of consideration of the upper end of the worldwide distribution of activity concentrations in soil provided by UNSCEAR.

15 IAEA Safety Guides for decommissioning DS452 DS403 In publication Revision of RS-G-1.7 has just started. DS499 and DS500 15

16 (2004) New Safety Guide on Application of the Concept of Exemption (DS499) New Safety Guide on Application of the Concept of Clearance (DS500) To be developed in parallel

17 New Safety Guide on Application of the Concept of Clearance - Justification The RS-G-1.7 was based on an older version of the BSS Basic information from the RS-G-1.7 incorporated into the new BSS (GSR Part 3), much of the information in RS-G-1.7 is now redundant Information in RS-G-1.7 on application of clearance still relevant, but MS noted it should be expanded to provide more details on: clearance process; establishment of national regulations; planning, organization and implementation; technical and safety implications; resources needed to implement the clearance process. RS-G-1.7 does not provide guidance on clearance of building and equipment based on surface contamination measurements, on clearance of liquids and gases and on conditional clearance NEW SAFETY GUIDE IS NEEDED

18 New Safety Guide on Application of the Concept of Clearance Objective and Scope The objective of the Safety Guide is to provide detailed guidance on the application of the concept of clearance for materials and buildings that are to be released from regulatory control. There is no intention to revise numerical values provided in GSR Part 3 Clarification on the use of terminology, especially the use of terms clearance and release; Responsibilities of the licensee and the regulatory body; All relevant steps of the clearance process including characterization, determination of the nuclide vector, measurement techniques, sampling, management of the clearance process; Mass specific and surface specific clearance criteria for unconditional clearance;

19 New Safety Guide on Application of the Concept of Clearance Objective and Scope Examples of derivation of mass specific and surface specific clearance criteria for conditional clearance (actual values would depend on specific conditions applied, so no universal set of values could be proposed); Case by case approach, which can be used for small quantities of material, or for other situations where the assumptions for the generic derivation of clearance levels do not apply; Provide explanations on needs for control of conditionally cleared materials (for example during transport), clarify at which point clearance act happens in case of conditional clearance; Clearance in an area affected by consequences of a nuclear or radiological accident; Considerations of clearance of liquids; Consideration of clearance of gases;

20 New Safety Guide on Application of the Concept of Clearance Objective and Scope Additional considerations for building materials containing naturally occurring radionuclides; Considerations of averaging masses and averaging areas; Discussion of the degree of homogeneity that was assumed in the calculation of the clearance levels and the implications for application of the clearance levels to non-homogenous material; Involvement of interested parties. The guide will not address: Application of radiological criteria for international trade of non-food commodities containing radionuclides (separate publication to be prepared) Release of sites from regulatory control (Safety Guide WS-G-5.1, its revision will be discussed soon).

21 New Safety Guide on Application of the Concept of Exemption Requirements of GSR Part 3 are structured around three types of exposure situations (planned, emergency, and existing). The concept of exemption in planned exposure situations and application of reference levels for existing exposure situations are both included in GSR Part 3, but supporting guidance on exemption has not yet been developed (RS-G-1.7 refers to practices and interventions). Section 5 of RS-G-1.7 on the application of the values for exemption needs to be updated to reflect use of the graded approach, in particular in the light of the conservative nature of the values. There is a need to provide guidance on the exemption process itself, ensuring consistency with SSG-36 that addresses exemption specifically as it applies to consumer products. There is also a need to develop surface specific criteria for exemption and provide guidance on the application of such criteria.

22 New Safety Guide on Application of the Concept of Exemption The guide will address: Exemption process Roles and responsibilities of the government, regulatory body and applicant Organizational and administrative arrangements Generic exemption application of values provided in GSR Part 3 Specific exemption - safety assessment, type approval exemption, revoking or revision of the exemption Exemption on the basis of surface contamination Annexes presenting dosimetric modelling and values for exemption based on surface contamination Will not address: Application of radiological criteria for international trade of non-food commodities containing radionuclides (separate publication to be prepared)

23 Commodities exemption and clearance Application of the Concepts of Exclusion, Exemption and Clearance (RS-G-1.7, 2004) If the values of activity concentration provided in this Safety Guide are used as indicated above, there should be no need for any further action (e.g. to reduce exposures) for materials containing radionuclides at activity concentrations below these values. In particular, national and international trade in commodities containing radionuclides with activity concentrations below the values of activity concentration provided in Tables 1 and 2 should not be subject to regulatory control for the purposes of radiation protection (para 5.8).

24 Comparison of standards - commodities Exemption and Clearance applies to planned exposure situations Dose criterion is 10 μsv individual dose in a year International trade is an existing exposure situation Dose criterion is 1 msv individual dose in a year

25 Other activities TECDOC on derivation of conditional clearance levels for disposal on municipal landfills draft completed, to enter the publication process Workshop on Derivation of Specific Clearance Levels for Materials that are Suitable for Disposal in Landfills, November 2017 in Vienna - to present the work done to the Member States New project on derivation of activity levels for material that is appropriate for civil engineering (dams, roads, etc.) to start in November 2017 Consultancy Meeting on management of large amount of waste containing residual levels of radionuclides and on derivation of specific clearance for materials that are suitable for reuse, 6-10 November, Vienna Several regional and national (Slovakia, Ukraine) workshops and training courses held in under the IAEA TC Programme

26 Development of specific clearance levels for disposal on landfills Clearance levels in RS-G-1.7 assume the use of the cleared material without any further restrictions Remediation waste e.g. after nuclear accidents may be generated in large quantities containing low levels of activity Demand from Member States for a simple methodology to evaluate disposal options for material with residual amounts of radionuclides IAEA derived specific clearance levels for disposal of waste on municipal landfills: draft report is available

27 Summary Concepts of exemption and clearance are related to graded approach to regulation of sources, practices and materials Clearance is an important option for management of material and waste from operation and from decommissioning of facilities, it enables for significant reduction of amounts to be managed as radioactive waste Increased interest in Member States and more frequent demands for assistance related to clearance, including conditional clearance The IAEA initiated revision of existing guidance on exemption and clearance - two Safety Guides and several supporting publications will be developed Participation of experts from Member States is essential for success of that process!

28 Summary General intention with the revision is to bring successful concepts, practices and experiences from some Member States into the IAEA Safety Standards, providing point of reference for other Member States who want to follow such approaches. Comments have been provided that the existing exemption and clearance values for artificial radionuclides are unnecessarily restrictive, and that the exposure scenarios used in their derivation are highly conservative. The revision process will not include derivation of new mass specific values for exemption and clearance, but will rather provide guidance on how to avoid, to the extent possible, additional layers of conservativism in other steps of the processes.

29 References IAEA GSR Part 3, Radiation Protection and Safety of Radiation Sources: International Safety Standards (2014) IAEA GSR Part 5, Predisposal Management of Radioactive Waste (2009) IAEA GSR Part 6, Decommissioning of Facilities (2014) IAEA SSG-47, Decommissioning of Nuclear Power Plants, Research Reactors and Other Nuclear Fuel Cycle Facilities (DS452) in publication, to supersede WS-G-2.1 and WS-G-2.4 IAEA RS-G-1.7, Application of Concepts of Exclusion, Exemption and Clearance (2004) under revision IAEA WS-G-5.1, Release of Sites from Regulatory Control on Termination of Practices (2006) IAEA SRS 44, Derivation of Activity Concentration Values for Exclusion, Exemption and Clearance (2005) IAEA SRS 67, Monitoring for Compliance with Exemption and Clearance Levels (2012)

30 Thank you!