Переводы документов. Translations in English

NP-013-99. Spent nuclear fuel processing plants. Safety requirements

Approved by

 

Approved by
Decree of
Gosatomnadzor of Russia
dated December, 27, 1999 No. 5

 

Effective from
September, 01, 2000

 

FEDERAL RULES AND REGULATIONS
IN THE AREA OF ATOMIC ENERGY USE

 

SPENT NUCLEAR FUEL PROCESSING PLANTS.

SAFETY REQUIREMENTS

 

NP-013-99

 

The regulatory document "Spent nuclear fuel processing plants. Safety requirements" regulates the specific safety issues for spent nuclear fuel processing plants as the source of potential radiation exposure for the workers, the public and the environment and establishes the principles, criteria and requirements aimed to ensure safety of the facilities for processing of spent nuclear fuel (fuel assemblies of power and research reactors, propulsion power units). The regulatory document shall be applicable to the designed, constructed and operated spent nuclear fuel processing plants.

The regulatory document is issued for the first time.

The regulatory document is developed in the Scientific and Technical Center for Nuclear and Radiation Safety of the Russian Gosatomnadzor.

Comments of Mayak Production Association, VNIINM RF SSC, SSCRF IPPE JSC, Federal Medical and Biological Agency of the Russian Ministry of Health, the Russian Ministry of Nuclear Energy, VNIPIET JSC and Mining and Chemical Works are reviewed and considered in the course of development.

 

ABBREVIATIONS

 

SNFPP SAR - Safety Analysis Report for Spent Nuclear Fuel Processing Plant

SFA - Spent Fuel Assembly

SNF - Spent Nuclear Fuel

SSCR - Self-Sustaining Chain Reaction

TP - Transport Packing

 

GENERAL TERMS AND DEFINITIONS.

 

The following terms and definitions are used in this document:

1. Accident - an operational occurrence at the SNF processing plant with release of radioactive substances and (or) ionizing radiation beyond the boundaries prescribed in the design for normal operation in the amounts exceeding the established safe operation limits. An accident is characterized by the initiating event, development scenarios and consequences.

2. Nuclear and radiation safety of the SNF processing plant (hereinafter  - safety of the SNF processing plant) - the property of the SNF processing plant to restrict radiation impact on the workers (personnel), the public and the environment down to the prescribed limits in the course of normal operation and in case of any operational occurrences including accidents.

3. Commissioning - the process in the course of which the systems (components) and equipment of the SNF processing plant begin to function, and their compliance with the design is verified. The process includes the precommissioning works and pilot operation and shall be completed with the SNF processing plant acceptance for commercial operation.

4. State of the art in science, technology and production - the set of scientific and technical knowledge, technological, design and engineering developments in certain areas of science and technology confirmed by scientific researches and practical experience and reflected in scientific and technical materials.

5. Single failure - deviation of any parameter, a failure or malfunction of any system component or a human error.

6. Beyond design basis accident - an accident caused by initiating events not considered for design basis accidents or accompanied by additional failures of safety system components as compared to design basis accidents in excess of a single failure and erroneous decisions of the workers.

7. Initiating event - a single failure in the systems (components) and equipment of the SNF processing plant, an external event or a human error resulting in any operational occurrence and capable of causing deviations from the safe operation limits and (or) conditions. The initiating event includes all dependent failures caused by it.

8. Conservative approach - approach to design and development when the values and limits knowingly leading to more unfavorable results shall be assumed for the parameters and characteristics in analysis of the accident causes.

9. Multiplication factor - the ratio of the total number of neutrons generated in the system within a certain time interval due to nuclear fission to the number of neutrons leaving the system due to absorption and leakage within the same time interval.

 In case this value is determined for the infinite medium or the endlessly recurrent grid it is called the infinite medium multiplication factor Kinf., and for the finite medium - the effective

neutron multiplication factor K

 eff.

10. Safety criteria - values of the parameters and (or) characteristics of the SNF processing plant established in the regulatory documents and (or) by the state regulatory authorities for safety in atomic energy use and used as the basis for its safety analysis.

11. Safety culture - professional and psychological preparedness of all workers when safety assurance at the SNF processing plant is a priority and inherent need leading to understanding of responsibility and self-control in performance of all safety-related works.

12. Local control room - the part of the SNF processing plant control system installed at the location of the controlled equipment and intended for occasional control of this equipment by the workers. The local control panel with the automation devices shall be installed in the local control room.

13. Operational occurrence at the SNF processing plant - any abnormal operation of the SNF processing plant with deviation from the established operation limits and conditions. In this case other limits and conditions established in the design particularly safe operation limits may be also exceeded.

14. Normal operation - operation of the SNF processing plant within the operating limits and conditions defined in the design.

15. Quality assurance - scheduled and systematically implemented activities intended to perform all works related to the SNF processing plant construction and operation in the established manner and to ensure compliance of their results with any prescribed requirements.

16. Common cause failures - failures of systems (components) caused by the same failure, or the same human error, or internal or external impact.

Notes.

1. Internal impacts (or causes) - impacts resulting from the initiating events of accidents including shock waves, jets, missiles, changes of the medium parameters (pressure, temperature, chemical activity, etc.), fires, etc., structural, process and any other internal causes.

2. External impacts - impacts of the natural phenomena and human activities typical for the location area of the SNF processing plant, for example earthquakes, hurricanes, transport accidents, fires, explosions at any facilities adjacent to the SNF processing plant, etc.

 

17. Human error - a single unintended erroneous impact on the controls, or a single  omission of any correct action, or a single unintended wrong action in the course of maintenance of the safety-related equipment and systems (components).

18. Accident consequences - the radiation situation caused by the accident and inflicting harm and losses due to exceedance of the established radiation exposure limits for the personnel, the public and the environment.

19. Safe operation limits of the SNF processing plant - values of the process parameters established in the design any deviations from which can lead to an accident.

20. Design basis accident - an accident with the initiating events and end states defined in the design and the provided safety systems aimed to assure mitigation of its consequences to the limits established for such accidents with due regard for the single failure principle or a human error independent from the initiating event.

21. Commercial operation of the SNF processing plant - operation of the SNF processing plant accepted for operation in accordance with the established procedure with confirmation of its safety and compliance with the design through testing at the commissioning stage.

22. Control room - the part of the SNF storage facility located in the dedicated rooms provided in the design and intended for centralized automated control of processes performed by the operating control personnel and automatic devices.

23. Self-sustaining chain reaction - the nuclide nuclear fission process when the number of neutrons generated in the course of nuclear fission within a certain time interval is equal or exceeds the number of neutrons leaving the system due to leakage and absorption within the same time interval.

24. System - the set of components intended for performance of the specified functions.

25. Safety-related systems (components) -  normal operation systems (components) in case their failures can disrupt normal operation of the SNF processing plant or impair elimination of any operational occurrences and can result in design basis and beyond design basis accidents.

26. Normal operation systems (components) - systems (components) intended for normal operation.

27. Construction of the SNF processing plant - the process for erection of the buildings and structures of the SNF processing plant including the package of construction works, equipment installation works, auxiliary, transportation and other works.

28. Safe operation conditions - the minimum requirements for quantity, characteristics, operability and maintenance conditions for the safety-related systems (components) established in the design when compliance with the safe operation limits and (or) safety criteria is assured.

29. SNF processing plant - a nuclear installation intended for SNF storage and processing, production and handling of nuclear materials, handling of radioactive substances and radioactive wastes in the prescribed modes and conditions located within the territory specified in the design where the set of the required systems, devices, equipment and structures with the necessary personnel is used for this purpose.

30. Operation - all activities aimed to achieve the purposes of the SNF processing plant construction in the safe manner, including SNF receiving, storage and processing, production and handling of nuclear materials, handling of radioactive substances and radioactive wastes, maintenance, repair, in-process inspections and any other associated activities.

31. Operation limits - the values of parameters and characteristics of the SNF processing plant systems (components) established in the design for normal operation.

32. Abnormal operation - operation of the SNF processing plant with deviations from the operation limits or conditions but without any exceedance of the safe operation limits or conditions.

33. Operation conditions - conditions for the quantity, characteristics, operability and maintenance of systems (components) established in the design and required for operation without any deviations from the operation limits.

34. Components - equipment, instruments, pipelines, cables, civil structures and others items ensuring performance of the prescribed functions independently or within the systems and considered in the design as structural units for reliability and safety analysis.

 

1. PURPOSE AND SCOPE OF APPLICATION

 

1.1. This document shall regulate specific safety issues for the SNF processing plants as the sources of potential radiation impact on the workers, the public and the environment.

1.2. This document establishes the principles, criteria and requirements aimed to ensure safety of the facilities for processing of spent nuclear fuel (fuel assemblies of power and research reactors, propulsion power units).

1.3. This document shall be applicable to the designed, constructed and operated spent nuclear fuel processing plants.

1.4. The scope and time limits for bringing of the constructed and operated SNF processing plants in compliance with this document shall be defined in each particular case in accordance with the procedure established in the license conditions for the relevant activities in the area of atomic energy use.

 

2. SAFETY ASSURANCE CRITERIA AND PRINCIPLES FOR
SPENT NUCLEAR FUEL PROCESSING PLANTS

 

2.1. A SNF processing plant shall be deemed to meet the safety requirements if its radiation impact on the workers, the public and the environment under normal operation conditions and in case of any operational occurrences including design basis accidents does not result in exceedance of the established radiation exposure dose limits for the workers and the public, norms of radioactive substance releases and discharges and content of radioactive substances in the environment and is also limited in case of any beyond design basis accidents.

2.2. Radiation exposure dose limits for the workers and the public, the permissible releases, discharges and content of radioactive substances in the environment shall be defined for normal operation conditions and accidents in accordance with the federal regulations and rules in the area of atomic energy use. Effective exposure doses for the workers and the public shall be below the established limits.

2.3. Safety of the SNF processing plant shall be assured through consistent implementation of the defense-in-depth principle based on the system of physical barriers in the way of ionizing radiation and radioactive substance propagation into the environment and the system of technical and administrative measures for protection of the barriers and maintenance of their efficiency.

2.3.1. The system of physical barriers of the SNF processing plant shall include:

- the first barrier - walls of the vessels (equipment), pipelines, containers with nuclear materials, radioactive substances and radioactive wastes;

- the second barrier - leak-tight rooms (canyons, hot chambers, etc.) where the equipment, pipelines and containers with nuclear materials, radioactive substances and radioactive wastes are located;

- the third barrier - civil structures of the buildings and facilities. Ventilation systems shall ensure direction of air flows and reduction of pressure from the external protective barriers towards the internal ones.

2.3.2. The system of technical and administrative arrangements for protection of the physical barriers shall form at least five defense-in-depth levels, namely:

Level 1 (prevention of any operational occurrences):

- assessment and selection of the site suitable for location of the SNF processing plant;

- arrangement of the sanitary-protective area and the supervised area around the SNF processing plant where the protective measures are planned;

- development of the SNF processing plant design (hereinafter - the design) based on the conservative approach;

- assurance of the required quality for the systems (components) of the SNF processing plant and the performed works;

- operation of the SNF processing plant in accordance with the regulatory documents, process regulations and operation manuals;

- operability maintenance for the safety-related systems (components) by timely detection of any defects, implementation of preventive measures, replacement of the equipment with exhausted lifetime and arrangement of the effective systems for documenting of the work and control results;

- selection and assurance of the required qualification level of the SNF processing plant personnel for actions under normal operation conditions and in case of any operational occurrences including accidents, formation of safety culture;

Level 2 (prevention of design basis accidents:

- timely detection of any deviations from the normal operation and their elimination;

- control in the course of abnormal operation;

Level 3 (prevention of beyond design basis accidents:

- prevention of development of initiating events into design basis accidents and  design basis accidents into beyond design basis accidents;

- mitigation of consequences of any accidents that could not have been prevented by confinement of the released radioactive substances;

Level 4 (management of beyond design basis accidents):

- prevention of development of beyond design basis accidents and mitigation of their consequences;

Level 5 (emergency planning):

- preparation and implementation (in case of necessity) of the emergency response plans at the SNF processing plant site and outside it.

2.3.3. The defense-in-depth concept shall be implemented at all stages of the activities related to safety assurance at the SNF processing plant. The strategy for prevention of any adverse events by implementation of Levels 1 and 2 of the defense-in-depth shall be of top priority.

2.4. Under normal operation conditions all physical barriers and the arrangements for their protection shall be operable and available. In accordance with the safe operation conditions the relevant systems of the SNF processing plant shall be shut down, or measures shall be implemented to bring them into the safe state if inoperability of any prescribed physical barrier or unavailability of the arrangements for its protection and operability monitoring is detected.

2.5. Arrangement of the safety-related systems (components), documentation and various types of works affecting safety assurance at the SNF processing plant shall be the subject of quality assurance activities.

2.6. The operating organization shall ensure development and implementation of the quality assurance arrangements at all stages of the SNF processing plant lifecycle; for this purpose it shall develop the general quality assurance program and control the activities of the organizations performing any works and (or) rendering any services to the operating organization.

The organizations performing any works and rendering any services to the operating organization (scientific, engineering, design, construction, installation, commissioning organizations, manufacturing plants of the equipment for the SNF processing plant, etc.) shall develop individual quality assurance programs for different types of activities within the framework of the general quality assurance program.

2.7. The operating organization shall ensure safety of the SNF processing plant and shall be fully responsible for it in accordance with the legislation of the Russian Federation, including the arrangements for prevention of accidents and mitigation of their consequences, accounting, control and physical protection of nuclear materials, radioactive substances and radioactive wastes, radiological control of the environment in the sanitary-protective area and the supervised area as well as usage of the SNF processing plant only for the intended purpose of its design and construction.

2.8. The system of technical and administrative arrangements for safety assurance at the SNF processing plant shall be presented in the SNFPP SAR developed by the operating organization or any other organization declaring its intention to construct and operate the SNF processing plant (the applicant). No discrepancies between the information contained in the SNFPP SAR and the design and its implementation are permitted. The operating organization shall maintain compliance of the SNFPP SAR with the actual state of the SNF processing plant within its entire service life.

2.9. Engineering features and administrative arrangements for prevention of any deviations from the safe operation limits and conditions shall be provided at the SNF processing plant.

2.10. The design shall provide for the measures aimed to mitigate any potential impact of beyond design basis accidents unless they are prevented by the inherent self-protection properties of the SNF processing plant systems (components), the principles of their arrangement and peculiarities of processes.

2.11. Reduction of any radiation exposure hazard for the workers, the public and the environment by implementation of the action plans for protection of the workers and the public shall be provided for beyond design basis accidents.

2.12. The lists of initiating events for design basis accidents and the list of beyond design basis accidents including their initiating events, development scenarios and consequences shall be defined in the design. The list shall include representative accident scenarios with severe consequences in order to define the possible response plan. In order to compile the list of beyond design basis accidents their realistic (non-conservative) analysis shall be performed with probability assessment for the development scenarios of each particular beyond design basis accident resulting in severe damage of the protective barriers.

Analysis of beyond design basis accident consequences presented in the design shall be used as the basis for development of the arrangements aimed to protect the workers and the public in case of accidents.

2.13. Technical and administrative solutions adopted for safety assurance at the SNF processing plant in the course of the equipment development and manufacturing, design, construction, operation, refurbishment and retrofitting of its systems (components) shall be field-proven by the previous experience or testing, studies and prototype operation experience and shall comply with the state of the art in science and technology as well as with the federal rules and regulations in the area of atomic energy use.

2.14. Physical protection, accounting and control of nuclear materials, radioactive substances and radioactive wastes shall be ensured at the SNF processing plant.

 

3. SAFETY ASSURANCE REQUIREMENTS
IMPLEMENTED IN DESIGN OF
SPENT NUCLEAR FUEL PROCESSING PLANTS

 

3.1. Safety-related systems (components) shall be designed in accordance with the federal rules and regulations in the area of atomic energy use and the safety criteria, principles and requirements specified in this document.

3.2. The design shall provide for the engineering features aimed to mitigate the consequences of beyond design basis accidents.

3.3. The design and detailed design documentation of the safety-related systems (components) shall provide for the devices and appliances as well as programs and methodologies for:

- checking of the system (component) operability;

- testing of the systems (components) for compliance with the design parameters;

- checking of the sequence of signal transmission and equipment actuation (including the emergency power supply sources);

- state monitoring for metal and weld joints of the equipment and pipelines;

- checking of the metrological characteristics of the measuring channels for compliance with the design requirements.

3.4. Safety-related systems (components) shall be capable to perform their functions within the scope defined in the design with due regard for the impact of any natural phenomena (earthquakes, hurricanes, floods possible in the SNF processing plant site location area), external human-induced events typical for the site selected for the plant construction and (or) any potential mechanical, thermal, chemical and other impacts of design basis accidents.

3.5. Arrangements aimed to prevent or to protect the systems (components) against any common cause failures shall be considered and substantiated in the course of the SNF processing plant design.

3.6. Preference to systems (components) with the structure based on the passive principle of action and inherent self-protection properties shall be given in the design of the SNF processing plant systems (components).

3.7. As a rule safety-related systems (components) shall be subject to direct and complete verification for compliance with the design parameters in the course of commissioning, after repair and periodically throughout the entire service life of the SNF processing plant.

In case direct and complete verification is impossible that should be confirmed in the design indirect and (or) partial verifications shall be performed. Sufficiency of any indirect and partial verification shall be justified in the design.

3.8. The SNFPP SAR shall contain the information on reliability parameters of the safety-related systems and their components. Reliability analysis shall be performed with due regard for common cause failures and human errors.

3.9. All utility networks crossing the boundaries of leak-tight rooms and capable of causing any release of radioactive substances outside the leak-tight rooms in case of any accident shall be equipped with isolating devices.

The permissible degree of untightness for the leak-tight rooms shall be substantiated in the design, and the ways to achieve it shall be specified. Compliance of actual leak-tightness with the design value shall be confirmed in the course of precommissioning works. Any equipment located inside the leak-tight rooms shall withstand testing without any loss of operability. The method and hardware aimed to test the leak-tight rooms for compliance with the design parameters shall be provided in the design.

3.10. Reliability substantiation for the protective barriers, safe operation limits and conditions for the safety-related systems (components) as well as any measures to be implemented in case of any deviation from these limits and conditions shall be reflected in the design.

3.11. The design shall provide for the following:

- control of the processes in all SNF processing plant operation modes with the quality and reliability parameters and metrological characteristics established in the design;

- reliable group and individual communication means between the control rooms, local control panels and the operating personnel;

- the means for collection, processing, documenting and storage of the information sufficient to provide the possibility for timely and unambiguous identification of the initiating events of any operational occurrences as well as accidents and their development;

- automatic and (or) automated diagnostics of the state and operation modes for the systems (components) including control and monitoring hardware and software;

- assurance of the most favorable conditions for the operating personnel in order to make correct decisions on the SNF processing plant control and to minimize the possibility for any erroneous decisions;

- the means to prevent single human errors or to mitigate their consequences, particularly in the course of maintenance.

3.12. The following shall be provided in the SNF processing plant control rooms:

- process control and monitoring means for normal operation conditionsm operational occurrences and design basis accidents;

- information support systems for the operator, including the system for in-process submittal of the consolidated information characterizing the current safety state of the plant to the workers.

Remote control commands for the process mechanisms generated by the automatic control systems or the remote control switches from the control room shall be recorded automatically.

3.13. The issues of the human-machnine interfaces shall be solved in the optimum way in the design of the SNF processing plant control systems. The parameters to be controlled in the control room shall be selected and displayed in order to ensure in-process submittal of unambiguous information on compliance with the safe plant operation limits and conditions to the workers.

3.14. Independent means for recording and storage of the information necessary to investigate accidents shall be provided. The above-mentioned means shall be protected against unauthorized access and shall retain their operability in case of any design basis and beyond design basis accidents. The scope of information to be recorded and stored shall be substantiated in the design.

3.15. The design shall provide for the technical and administrative arrangements aimed to prevent the SSCR occurrence and to mitigate its potential consequences. Predominant use of the equipment with the design and geometrical peculiarities preventing any possibility for the SSCR occurrence shall be provided in selection of the design solution. Usage of any other equipment shall be substantiated in the SNFPP SAR.

3.16. Nuclear safety assurance at the SNF processing plant shall be achieved via:

- restrictions imposed on the geometrical shape and dimensions of the equipment;

- limitation of the mass of nuclear-hazardous fissile nuclides, substance, material, their isotope composition and concentration;

- limitation of the nuclear-hazardous fissile nuclide concentrations;

- usage of homogeneous and heterogeneous neutron poisons;

- restriction of the nuclear-hazardous fissile material isotope composition;

- limitation of the neutron moderator weight parts in the nuclear-hazardous fissile material;

- restrictions imposed on the reflectors and on location of the equipment;

- combinations of the above-mentioned methods and restrictions.

 The neutron multiplication factor K shall not exceed 0.95 under normal operation conditions. At the same time the safety factors shall be at least 2.1 with regard to mass; at least 1.3 with regard to concentration and volume; at least 1.1 with regard to the cylinder diameter and the layer thickness. In case of any single failure K shall not exceed 0.98; in this case the safety margin shall be at least 1.05.

3.17. The design shall provide for radiological control of the SNF processing plant in the rooms and at the site, in the sanitary-protective area and the supervised area in the course of the plant operation (including accidents) and decommissioning. The systems for continuous and periodic monitoring of the content of radioactive and toxic substances in the air of the SNF processing plant rooms, releases and discharges from the plant systems and equipment shall be provided in the design.

The scope, methods and means of radiological control shall ensure:

- control of exposure level for the workers;

- timely detection of any radiation situation changes in the SNF processing plant rooms, at the site, in the sanitary-protective area and the supervised area;

- timely warning of the workers on any deterioration of the radiation situation in the SNF processing plant rooms and at the site through the use of acoustic and light alarms;

- analysis of any causes of the radiation situation deterioration;

- selection of the solutions for the radioactive contamination confinement.

3.18. Usage of the mandatory radiological control system for the workers as well as vehicles, substances and materials on the boundaries of the SNF processing plant site shall be provided in the design.

3.19. The solutions provided in the design shall be aimed to restrict usage of explosion- and fire-hazardous, pyrophoric, corrosive and toxic substances and materials in the operating processes.

3.20. The design shall provide for safe handling of all nuclear materials and radioactive substances in all operation modes including design basis accidents. Reliable and safe storage of the chemical agents used at the SNF processing plant as well as representative sampling of the process media in handling of nuclear materials and radioactive substances shall be ensured.

3.21. The design shall provide for technical and administrative arrangements aimed to prevent ignition of steam, gas and air mixtures and uncontrolled decomposition of  any mixtures of organic substances with oxidizing agents.

Arrangement of the fire alarm and fire extinguishing systems with automatic activation and activation by the operator's command shall be provided in the design. Any process operations with self-igniting materials shall be carried out in the inert gas environment. Usage of fire-resistant cables shall be provided.

3.22. The design shall provide for the following:

- acceptance of the SFA specified in the repository design and the range of SFA subject to treatment at the SNF processing plant for storage;

- control of the SFA delivered to the plant for compliance of the actual characteristics with the certificate data;

- radiological control in the SNF TP unloading room;

- purification and cooling of the water in the SFA pool and reliable maintenance of the required quality of water. Quality of water in the SFA pool shall ensure maintenance of the SFA integrity in the course of their storage and handling as well as integrity of the repository lining within the entire service life specified in the design;

- SFA transportation only in the special-purpose containers (TPs, casings) ensuring safe rate of loading and also SFA storage in the pools in compartments and cells intended for the particular type of fuel assemblies;

- transportation and handling equipment for spent fuel assemblies, the means for its maintenance and repair.

3.23. The design shall provide for the methods and means aimed to prevent any operational occurrences in the SNF processing plant systems (components), particularly:

3.23.1. Control methods and means for:

- the nuclear safety parameters including the SSCR emergency alarm systems;

- content of nuclear materials in the process media;

- compliance with the nuclear material loading rates for the equipment;

- accumulation of nuclear materials in the process equipment, including gas treatment equipment;

- content of hydrogen and other explosive and fire-hazardous gases;

- completeness of the nuclear fuel solution in the dissolving unit;

- content of uranium and plutonium in raffinates and bottoms;

- salt composition of the raffinates and bottoms;

- temperature of solutions in the storage tanks for high-level radioactive wastes;

- temperature and pressure in extraction and sorption equipment;

- level of process solutions in the sorption equipment;

- cooling water flow rate in the heat exchangers of the storage tanks for high-level radioactive wastes;

- content of nitric acid and other macro-components in the process media;

- content of the organic phase (extraction agent) in the process media;

- formation of the nitric acid mixtures with organic substances in the dead zones;

- formation of explosive gas concentrations in the rooms;

- composition of the chemical agents.

3.23.2. Methods, means and devices for:

- movement of process media and products with the maximum possible use of vacuum or gravity flow;

- usage of inert gases or air for dilution of gaseous explosive and fire-hazardous mixture in the equipment;

- prevention of any uncontrolled absorbent carry-over from the sorption equipment;

- displacement of the process solutions from the sorption equipment with water;

- extraction of organic solution from the final uranium re-extract prior to uranyl nitrite melt or concentrate production;

- elimination of any possibility for non-regulatory mixing of the process products;

- prevention of the sorption equipment rupture in case of intensive gas emission.

3.24. The structural materials shall comply with the operating process with regard to their strength characteristics, low sorption capacity in relation to radionuclides, corrosion resistance in aggressive media, radiation stability under the impact of ionizing radiation. The applied materials shall be non-combustible or slow-burning.

3.25. The possibility for decontamination and (or) removal of the equipment and pipelines shall be provided in the design in order to enhance safety in the course of the equipment maintenance and repair. Methods and means for elimination of any accidental contamination of the rooms and equipment and their decontamination shall be provided.

3.26. Layout of the SNF processing plant equipment shall ensure convenience in the course of operation, maintenance and repair,   particularly:

- collection of leakages and spillages eliminating radioactivity propagation beyond any further physical barriers;

- the minimal possible length of pipelines;

- the minimal possible number of shut-off devices and detachable joints;

- absence of any non-drained dead zones.

3.27. The design shall provide for safe handling of all generated radioactive waste types in all SNF processing plant operation modes including design basis accidents at the plant. Safety assurance criteria and principles in the course of radioactive waste handling as well as the requirements for safety assurance shall be established by the federal regulations and rules in the area of atomic energy use.

3.28. Separate ventilation of the controlled access area rooms and the uncontrolled access area of the SNF processing plant buildings shall be provided in the design in order to prevent contamination of air in the rooms and the environment with radioactive substances and to maintain the climatic conditions required for normal operation of the equipment. The SNF processing plant ventilation system shall prevent any ingress of the air from the controlled access area to the rooms of the uncontrolled access area.

3.29. The design shall provide for general plenum and exhaust and process ventilation systems ensuring direction of the air flows and pressure reduction from the external protective barriers towards the internal ones.

3.30. Exhaust ventilation of the rooms belonging to Zones I, II and III defined in accordance with sanitary rules shall be arranged through the use of separate ventilation systems. No air flow from Zone I to Zones II and III and from Zone II to Zone III is permitted.

3.31. Ventilation systems of Zone I shall be equipped with:

- emergency alarm for the regulated underpressure decrease in the process chambers and boxes;

- alarm for the regulated underpressure decrease in the process chambers and boxes;

- underpressure monitoring in the air ducts;

- pressure differential monitoring for the filters;

- air flow rate control.

Ventilation systems of Zone II shall be equipped with:

- air flow rate control;

- pressure differential monitoring for the filters.

Ventilation systems of Zone III shall be equipped with:

- air flow rate control.

3.32. The design shall provide for technical and administrative arrangements aimed to ensure security of the nuclear materials, radioactive substances and radioactive wasts at the plant, to prevent any unauthorized intrusion to the plant territory, to prevent unauthorized access to nuclear materials, radioactive substances and radioactive wastes and to ensure timely detection and suppression of any sabotage and acts of terrorism posing any hazard for the SNF processing plant safety.

 

4. SAFETY ASSURANCE IN OPERATION OF THE SPENT NUCLEAR FUEL
PROCESSING PLANTS

 

4.1. The operating organization shall arrange the required organizational structures for safe operation of the SNF processing plant, grant the necessary authorities to the plant administration, provide the required financial, material and equipment resources, regulatory documents and scientific and technical support for the plant, ensure physical protection and fire safety, arrange selection and training of the workers, create the conditions when safety of the SNF processing plant is considered as vital affair and the personal responsibility of all workers and carry out continuous supervision over the plant safety.

4.2. The operating organization shall ensure continuous supervision over all safety-related activities at the SNF processing plant and submit regular safety assessment reports for the plant to Gosatomnadzor of Russia.

4.3. Precommissioning works shall confirm that the entire SNF processing plant as well as its systems (components) and equipment are arranged and function in accordance with the design, and any revealed defects are eliminated. The plant administration shall arrange development of the precommissioning work programs and their coordination with the designers. The program shall be approved by the operating organization and submitted to Gosatomnadzor of Russia in accordance with the established procedure in order to obtain permits for individual stages of the works. Documents regulating performance of the precommissioning works and pilot operation shall contain the list of nuclear- and radiation-hazardous works and the list of measures for prevention of accidents.

4.4. Characteristics of the SNF processing plant systems (components) and equipment shall be defined and documented in the course of the commissioning program implementation.

The list of parameters to be documented shall be defined in accordance with the relevant testing programs. The performance characteristics of the systems (components) and equipment, safe operation limits and conditions shall be adjusted in order to present the actual characteristics of the systems (components) and equipment fairly.

4.5. Operability of the systems (components) shall be verified, and condition of metal and weld joints of the plant systems (components) and equipment shall be controlled prior to commissioning of the SNF processing plant and also regularly in accordance with the requirements of the design and regulatory documents. Frequency and scope of the regular inspections shall be defined in the schedules developed by the plant administration. The above-mentioned schedules shall comply with the effective regulatory documents and depend on the function of the inspected system (component) in the SNF processing plant safety assurance with due regard for quantitative reliability analysis for the systems (components).

4.6. Subsequent to successful trial of the SNF processing plant systems (components) and equipment it shall be accepted for commercial operation. Acceptance for operation shall be arranged in accordance with the procedure set by the legislation.

The SNF processing plant operation license shall be granted by Gosatomnadzor of Russia to the operating organization subsequent to completion of all plant commissioning works and subject to availability of the SNFPP SAR updated in accordance with the SNF processing plant commissioning results and the certificate of plant acceptance for commercial operation.

4.7. Process regulations containing rules and basic techniques of safe operation, the general procedure for safety-related operations as well as safe operation limits and conditions shall be the main documents regulating safe operation of the SNF processing plant. The operating organization shall ensure development of the process regulations in accordance with the SNFPP SAR as well as on the basis of the design documentation.

4.8. Prior to precommissioning works the SNF processing plant administration shall ensure development of the operation guidelines based on the approved process regulations and the documentation provided by the developers of the operating processes and equipment as well as the design developer. Operation guidelines for the systems  (components) and equipment shall contain specific instructions for the workers related to work practices in the course of normal operation and in case of any operational occurrences including accidents. The above-mentioned operation guidelines shall be adjusted subsequent to the SNF processing plant commissioning results.

4.9. Maintenance, repair, testing and inspections shall be provided in order to maintain operability of the systems (components) and equipment and also to prevent any dangerous failures in the systems. The above-mentioned works shall be performed in accordance with the relevant guidelines, programs, schedules and flow sheets developed by the SNF processing plant administration on the basis of the design requirements and process regulations and shall be documented. The safety conditions established in the process regulations on the basis of the design shall be observed in the course of maintenance, repair, testing and verification of the systems (components) and equipment. Arrangements aimed to eliminate any possibility for unauthorized changes of the process flow diagrams and equipment shall be provided.

Guidelines, programs, schedules and flow sheets shall contain detailed description of the following procedures:

- issuance of work permits for the workers;

- removal of process products from the equipment;

- decontamination works;

- radiological and dosimetric control;

- the procedure and sequence of disabling for the systems and equipment;

- the procedure and sequence of the equipment installation and dismantling;

- the procedure for opening of the canyons and process chambers;

- the procedure for handling of the generated radioactive wasts as well as any other requirements and conditions aimed to ensure safety of the workers.

Subsequent to maintenance the systems (components) shall be checked for operability and compliance with the design characteristics, and the results of such checks shall be documented.

4.10. The procedure for maintenance, storage and review of the operation documentation shall be established in the relevant regulatory documents. The design, as-built documentation for construction, testing reports and as-built documentation for maintenance and repair of the safety-related systems (components) shall be stored at the SNF processing plant within the entire period of its operation.

4.11. Documented information on monitoring of the safe operation limits and conditions shall be stored within two years. Prior to disposal of the records the results shall be included into regular reports issued by the operating organization. Materials on investigation of any operational occurrences at the SNF processing plant shall be stored within the entire period of its operation.

4.12. The relevent systems of the SNF processing plant shall be shut down in case of any impossibility to comply with the certain safe operation limits and conditions.

4.13. Any testing not provided in the process regulations and operation guidelines shall be carried out in accordance with the programs and methods containing the safety assurance measures for these tests. The testing programs and methods shall be coordinated with the design developer as well as with the developers of equipment and operating processes and approved by the operating organization.

4.14. Any operational occurrences at the SNF processing plant shall be investigated by the commissions appointed in accordance with the effective provisions. The operating organization shall be responsible for completeness and quality of the investigation, prompt submittal of the investigation results to Gosatomnadzor of Russia, any other concerned parties and the sate atomic energy controlling agencies in accordance with the established procedure, analysis of the accident causes with the workers of the operating and constructed plants, development and implementation of the measures aimed to prevent any repeated operational occurrences and accidents.

4.15. Collection, processing, analysis, systematization and storage of information on any failures of the systems and equipment and erroneous actions of the workers as well as its prompt submittal to all concerned parties including the design developer in accordance with the established procedure shall be ensured in the course of the SNF processing plant operation.

4.16. All proposed specific technical resolutions on any changes in the design of equipment as well as installation and process flow diagrams shall be substantiated, coordinated by the SNF processing plant administration with the design developers and implemented subsequent to introduction of changes into the license conditions.

4.17. Action plans for protection of the workers and the public in case of any accident at the plant shall be developed and ready for implementation prior to commencement of the SNF processing plant commercial operation. The action plan for protection of the workers in case of any accident at the plant shall be developed by the operating organization. The action plan for protection of the public shall be developed by the competent executive authorities in accordance with the established procedure.

The main and redundant lines for communications with any organizations specially authorized in protection of the public and territories against emergencies shall be implemented prior to commencement of the SNF processing plant commercial operation in accordance with the plans for protection of the workers and the public.

 

5. SAFETY ASSURANCE IN DECOMMISSIONING OF
THE SPENT NUCLEAR FUEL PROCESSING PLANTS

 

5.1. Decommissioning of the SNF processing plant shall be taken into account in the course of the plant design, operation, maintenance and repair.

5.2. The operating organization shall ensure development of the plant decommissioning program prior to expiry of the design service life of the SNF processing plant and submit any resulting changes of the SNF processing plant operation license conditions to Gosatomnadzor of Russia for formalization in accordance with the established procedure.

5.3. Comprehensive examination of the SNF processing plant shall be performed prior to decommissioning by the commission appointed by the operating organization. The operating organization shall ensure development of the SNF processing plant decommissioning project based on the comprehensive examination materials and prepare the safety analysis report for the SNF processing plant decommissioning in order to obtain the decommissioning license from Gosatomnadzor of Russia.

5.4. The SNF processing plant shut down for decommissioning shall be deemed in operation until removal of all nuclear materials. Within this period all requirements for the workers, documentation, etc. shall remain the same as for the operating SNF processing plant. Reduction of maintenance scope, decommissioning of individual systems (components), reduction of the personnel size shall be carried out in compliance with the changes introduced to the plant operation license conditions in accordance with the established procedure.

 

 


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