By combining with the practical experience of reprocessing plant’s decommissioning activities in China, this standard is compiled by reference to Decommissioning of Nuclear Fuel Cycle Facilities (No. WS-G-2.4, 2001.7 of safety guidelines) and Decommissioning of Non-reactor Nuclear Facilities (No. 386 of technical report series) published by the International Atomic Energy Agency and other relevant documents.
This standard was proposed by the China National Nuclear Corporation.
This standard is under the jurisdiction of the Institute for Standardization of Nuclear Industry (ISNI)).
Drafting organization of this standard: Beijing Institute of Nuclear Engineering (BINE).
Chief drafters of this standard: Bao Fang, Wu Zhongyao, Zhao Huasong.
Safety Criteria for Decommissioning Design of Spent Fuel Reprocessing Plant
核燃料后处理厂退役设计安全准则
1 Scope
This standard specifies the safety criteria for decommissioning design of spent fuel reprocessing plant.
This standard is applicable to the decommissioning design of normally closed spent fuel reprocessing plants; the decommissioning design of reprocessing plants closed abnormally and facilities for processing radioactive waste may also refers to this standard.
2 Normative References
The following documents contain provisions which, through reference in this standard, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding any corrigendum), or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated references, the latest edition of the document referred to applies.
GB/T 4960.3 Glossary of Nuclear Science and Technology - Nuclear Fuel and Nuclear Fuel Cycle
GB/T 4960.5 Glossary of Terms: Nuclear Science and Technology - Radiation Protection and Safety of Radiation Sources
GB/T 4960.8 Glossary of Term: Nuclear Science and Technology - Radioactive Waste Management
GB 9133 Classification of Radioactive Waste
GB 11806 Regulations for the Safe Transport of Radioactive Material
GB 14500 Regulations for Radioactive Waste Management
GB 18871-2002 Basic Standards for Protection Against Ionizing Radiation and for the Safety of Radiation Sources
GB/T 19597 Safety Requirements for Decommissioning of Nuclear Facilities
EJ 1186 Characterization of Radioactive Waste Forms and Packages
EJ/T 1203 Requirements of Radiation Program for Decommissioning Operations of Nuclear Facilities
3 Terminologies and Definitions
For the purposes of this standard, the terminologies and definitions specified in GB/T 4960.3, GB/T 4960.5 and GB/T 4960.8 and the following ones apply.
3.1
Decommissioning
The administrative and technological actions taken to remove some or all of the regulatory controls from a nuclear facility for the purpose of protecting the health of workers and the public as well as the environment when the facility stops service due to the expiration of service term or other reasons. However, this definition is not applicable to the close of waste disposal site or specific uranium mining and metallurgy facilities.
3.2
Waste minimization
During all the stages from facility design to decommissioning, the volume and activity concentration of radioactive waste are kept at possible lowest levels that can be reached reasonably by taking such measures as reducing the waste production, recycling and reusing, and disposing primary waste and secondary waste properly.
4 General Safety Requirements of Decommissioning Design
4.1 Safety objective
The safety objective of decommissioning design is to ensure safe decommissioning and that the hazard of radioactive substances and non-radioactive toxic and harmful substances to workers, the public and the environment is lower than the specified limit and kept at possible lowest levels that can be reached reasonably by making optimization analysis.
4.2 Radiation safety
4.2.1 Radiation protection design shall meet the requirements of GB 18871-2002. In the preparation stage of decommissioning, it needs to prepare decommissioning radiation protection and monitoring outlines of which the contents shall meet the requirements of GB/T 19597 and EJ/T 1203.
4.2.2 Areas involved in decommissioning activities shall be subjected to partition management in accordance with the requirements of 6.4 of GB 18871-2002. The direction of people, goods and air stream shall be organized reasonably. With the progress of decommissioning activities, radioactive area division may be adjusted timely.
4.2.3 As for the decommissioning implemented in sites with high level of radioactive dose, shielding measures or remote operation shall be considered.
4.2.4 As for the decommissioning implemented in site with higher surface contamination level or α emitter contamination, appropriate isolation measures shall be taken, and effective air exhaust and purification measures shall be adopted; if necessary, ventilated suit shall be adopted.
4.2.5 Reasonable working sequence of decommissioning shall be formulated in order to avoid cross contamination.
4.2.6 As for operation on facilities with possible contamination expanding, preventive measures shall be considered to avoid unacceptable exposure dose.
4.3 Waste safety
4.3.1 Solid waste generated by decommissioning shall be classified, collected, conditioned, packaged, temporarily stored, transported, treated and disposed according to the requirements of GB 9133, GB 14500, and EJ 1186.
4.3.2 Liquid waste generated by decommissioning shall be discharged after separate collection and treatment; and gases generated by decommissioning shall be discharged after purification.
4.3.3 During the design and implementation of decommissioning, optimized technology shall be adopted and waste minimization shall be achieved by taking such measures as reducing generation, separate collection, volume reduction, conditioning and recycle and reuse as well as strengthening waste monitoring and strictly enforcing supervision and management system.
4.3.4 Sealing measures shall be taken for α-waste to prevent α aerosol from overflowing.
4.4 Environmental safety
4.4.1 Necessary discharge monitoring point(s), monitoring point(s) for the sampling of atmosphere, soil, surface water, groundwater radioactivity and levels of environmental γ radiation shall be arranged according to the requirements of decommissioning design.
4.4.2 Inspected substances and items which conform to the requirements of 4.2.5 of GB 18871-2002 may be subjected to clearance.
4.4.3 In the design, it needs to ensure that the annual effective dose caused by residual radioactive substances to the public and the individual shall be lower than the specified management objectives value at the final state of decommissioning.
4.5 Industrial safety
In the decommissioning design, the non-radioactive occupational hazards shall be analyzed and corresponding precaution measures shall be adopted, including:
a) Hazards generated by using high temperature high pressure apparatus;
b) Hazards generated by using electrified equipment;
c) Hazardous factors analysis of fire hazard and the setting of fire protection facilities;
d) Hazards of dust, toxic and harmful substances;
e) Hazards of explosive or toxic gases;
f) Noise control;
g) Hazards of mechanical injury and high-place operation accident.
4.6 Other safeties
4.6.1 When system and equipment containing fissile materials are involved in the decommissioning activities, adequate measures shall be taken to ensure the criticality safety.
4.6.2 The transportation of decommissioning waste shall be designed and organized according to GB 11806 and relevant national regulations and specifications for radioactive substances and hazardous material transportation.
4.6.3 Durability of long-term buried (hidden) facilities and devices in predicted buried (hidden) period and environment shall be fully considered, and necessary measures shall be taken before burying (hiding) to ensure their long-term stability.
Foreword i
1 Scope
2 Normative References
3 Terminologies and Definitions
4 General Safety Requirements of Decommissioning Design
5 Radioactive Characteristic Investigation
6 Clear-up of Radioactive Materials
7 Decontamination
8 Dismantlement of Systems and Equipment
9 Demolition of Buildings (Structures)
10 Environment Management for Plant Area within Decommissioning Range
11 Safety Management of Decommissioning Waste
12 Accident Emergency
13 Quality Assurance
