Federal Environmental, Industrial and Nuclear Supervision Service
FEDERAL RULES AND REGULATIONS
IN THE FIELD OF ATOMIC ENERGY USE
|
Approved
by the Decree |
RULES FOR ARRANGEMENT AND OPERATION OF SAFETY-RELATED VENTILATION SYSTEMS
OF NUCLEAR POWER PLANTS
NP-036-05
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Effective
from |
Moscow 2005
These Federal rules and regulations "Rules for arrangement and operation of safety-related ventilation systems of nuclear power plants" establish the basic requirements for ventilation systems of nuclear power plants classified as safety-related normal operation systems and for ventilation systems referred to supporting or localizing safety systems.
These Federal rules and regulations take into account the amendments introduced to the previous document NP-036-02 "Rules for arrangement and operation of safety-related ventilation systems of nuclear power plants" *.
They shall be applicable to designed, constructed, operated, refurbished and decommissioned power units of nuclear power plants and establish specific requirements related to operation of ventilation systems.
Developed with due regard for the federal rules and regulations and the IAEA documents regulating the requirements related to operation of safety systems.
The regulatory document
has passed legal examination at the Ministry of Justice of Russia (Letter of
the Ministry of Justice of Russia No. 01-3537-EZ dated 24.11.2005).
__________________________
* This revision of the regulatory document is developed in the Scientific and Technical Center for Nuclear and Radiation Safety with contributions from A.M. Bukrinsky, V.A. Dvukhimenny, E.M. Klementieva, O.M. Kovalevich (Scientific and Technical Center for Nuclear and Radiation Safety), V.D. Bumagin, G.I. Kholupkova (State Scientific Research, Design and Engineering Institute "Atomenergoproekt"), I.V. Yagodkin (State Scientific Center of the Russian Federation "Institute of Physics and Power Engineering").
Comments from the specialists of the Scientific and Technical Center for Nuclear and Radiation Safety of the Federal Environmental, Industrial and Nuclear Supervision Service, Balakovo, Kursk, Kola, Novovoronezh and Smolensk NPPs, Department of Environment and Decommissioning of Nuclear Facilities of the Federal Atomic Energy Agency, Rosenergoatom, VNIIAES, SUE OKBM, NIAEP, SPb AEP were reviewed and taken into account in the course of development.
Contents
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1. |
Purpose
and scope |
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2. |
General
requirements for safety-related ventilation systems of nuclear power plants |
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3. |
Requirements
for design of safety-related ventilation systems of nuclear power plants |
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3.1. |
General
requirements |
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3.2. |
Requirements
for plenum ventilation systems |
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3.3. |
Requirements
for exhaust ventilation systems |
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3.4. |
Requirements
for recirculation systems |
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3.5. |
Requirements
for aerosol and iodine filters |
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4. |
Requirements
for installation and operation of safety-related ventilation systems of nuclear power plants |
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4.1. |
General
requirements |
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4.2. |
Requirements for control of safety-related ventilation systems of nuclear power plants |
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1.1. The Rules for arrangement and operation of safety-related ventilation systems of nuclear power plants (hereinafter - the Rules) establish the basic requirements for:
1.2. These Rules shall be applicable to designed, constructed, operated, refurbished and decommissioned power units of nuclear power plants (NPPs) and establish specific requirements related to operation of ventilation systems.
1.3. These Rules shall not be applicable to non-safety-related NPP ventilation systems: these systems shall be developed and constructed in accordance with the NPP construction and operation standards and rules.
2. GENERAL REQUIREMENTS FOR SAFETY-RELATED VENTILATION SYSTEMS OF NUCLEAR POWER PLANTS
2.1. Ventilation systems and their components referred to safety-related systems (hereinafter - the ventilation systems) shall be defined in the NPP design. Classification of ventilation systems as safety-related systems shall be performed in accordance with the requirements of General Safety Provisions for Nuclear Power Plants.
2.2. Classifications of the ventilation systems according to their purpose, nature of the performed safety functions, seismic categories and requirements for power supply categories shall be established and substantiated in the NPP design in compliance with the federal rules and regulations in the field of atomic energy use and reflected in the safety analysis report for the nuclear power plant (hereinafter - the NPP SAR).
2.3. Safety-related normal operation ventilation systems shall be defined in the NPP design.
2.4. Ventilation systems performing any safety functions in case of accidents at the NPP shall be defined in the NPP design.
2.5. Characteristics of safety-related normal operation ventilation systems and ventilation systems performing safety functions in case of any accidents at the NPP shall be substantiated in the NPP design and specified in the NPP SAR.
2.6. Ventilation systems and components performing the functions of supporting or localizing safety systems may be used during normal operation of the NPP provided that it does not result in any violation of the requirements for the NPP safety assurance and reduction of required reliability for systems and components performing safety functions.
3. REQUIREMENTS FOR DESIGN OF SAFETY-RELATED VENTILATION SYSTEMS OF NUCLEAR POWER PLANTS
3.1.1. The following shall be defined in the NPP design for plenum, exhaust and recirculation ventilation systems functioning under normal operation conditions and (or) performing any safety functions in case of accidents at the NPP:
Design characteristics and reliability parameters of plenum, exhaust and recirculation ventilation systems shall be justified in the NPP design and presented in the NPP SAR.
3.1.2. The NPP design shall specify the following:
3.1.3. The NPP design shall provide for the engineering features and administrative measures aimed to ensure stability of the parameters affecting efficiency of air purification in aerosol and iodine filters.
3.1.4. The operating procedure shall be specified in the NPP design for each ventilation system and contain the data defining:
3.1.5. Ventilation systems shall be checked for compliance with the design parameters in the course of commissioning, after repair and periodically within the entire NPP service life.
3.1.6. Rooms or ventilated areas shall be arranged for repair, maintenance and temporary storage of the system equipment (filters).
3.1.7. The number of plenum and exhaust ventilation systems shall be defined in the NPP design with due regard for segregation of the rooms in accordance with the zoning, location of safety system equipment in the rooms, fire hazard category of the rooms and categories of the rooms in the controlled access area.
3.1.8. Air exchange in the rooms of the controlled access area shall be determined so that to maintain the required underpressure and temperature under normal operation conditions and in the course of repair (based on the air velocity in the door opening complying with the Sanitary rules for design and operation of nuclear power plants).
3.1.9. The NPP design shall provide for connection of the gas venting system pipelines to the collecting ventilation skip of the vent stack only after treatment of the gas vents in the filtration systems.
3.1.10. Materials of the ventilation system components or their coatings shall be defined with due regard for the impact of the following factors:
3.1.11. Design of the ventilation system components in the rooms of the controlled access area shall enable their decontamination.
3.1.12. The NPP ventilation systems referred to safety systems shall:
3.1.13. The permissible delay time for automatic activation of the back-up ventilation system components referred to safety systems after failure of the main ones shall be defined and substantiated in the NPP design and specified in the NPP SAR.
3.1.14. Reliable power supply shall be ensured for the ventilation units of the ventilation systems (gas blowers, fans) referred to safety systems. Reliability category for connection of the ventilation system components to reliable power supply systems shall be substantiated in the NPP design and reflected in the NPP SAR.
3.2. Requirements for plenum ventilation systems
3.2.1. Air intakes of the plenum ventilation shall be protected against ingress of precipitation. Air intakes shall be located in such a way so that to prevent any ingress of discharges from the exhaust ventilation systems, gases from the stand-by diesel-generator station, steam, explosive mixtures and toxic substances.
3.2.2. Independent personnel habitability systems with purification of air from radionuclides and measures aimed to prevent any ingress of toxic substances and gases into the rooms shall be provided for main and emergency control rooms.
3.2.3. The plenum ventilation system shall be switched off automatically upon switch-off of the corresponding exhaust ventilation system.
3.2.4. Filters with the atmospheric dust collection efficiency of not less than 80% shall be installed in the plenum ventilation systems.
3.2.5. The plenum ventilation systems shall be equipped with the devices to compensate for any potential reduction of air flow supplied to the NPP rooms below the value substantiated in the NPP design due to the filter resistance increase.
3.3. Requirements for exhaust ventilation systems
3.3.1. The exhaust ventilation systems of the NPP rooms where any ingress of radioactive substances is possible under normal operation conditions and in case of abnormal operation shall be equipped with filters.
The type of filters (aerosol and (or) iodine) installed in the exhaust ventilation systems shall be substantiated in the NPP design.
3.3.2. Collection efficiency for ventilation air in the aerosol filters of the exhaust ventilation systems within their entire service life shall be at least equal to 99.95% for the most penetrating particles.
3.3.3. The exhaust ventilation systems equipped with aerosol and iodine filters shall have the devices aimed to maintain capacity of the ventilation units within the design limits and to control collection efficiency of the filters.
3.3.4. Ventilation units, aerosol and iodine filters of the exhaust ventilation systems shall be located in the controlled access area in isolated rooms equipped with biological protection, decontamination means and hoisting mechanisms.
3.3.5. Underpressure shall be provided in the rooms where the equipment of the exhaust ventilation systems is located by arrangement of exhaust ventilation with the air outflow exceeding the air inflow by at least single air exchange in the room per 1 hour or by arrangement of air inflow through pressure relief valves.
3.4. Requirements for recirculation systems
3.4.1. Recirculation cooling systems shall maintain the necessary conditions in order to ensure operability of the equipment and also the required climatic parameters in the serviced rooms according to the sanitary standards in all operation modes prescribed in the NPP design.
3.4.2. Aerosol filters with the collection efficiency of less than 99.95% for the most penetrating particles may be used for air purification in the recirculation systems. The efficiency value shall be substantiated.
3.5. Requirements for aerosol and iodine filters
3.5.1. Calculation of collection efficiency for purification of ventilation air in the aerosol filters shall be substantiated in the NPP design with due regard for the following conservative assumptions:
3.5.2. Efficiency of the filters intended for collection of radioactive iodine from ventilation air shall ensure the collection efficiency established in the NPP design separately for molecular iodine and organic iodine forms.
3.5.3. Absorptive capacity of the applied sorbents and the total amount of iodine supplied to the filters within their entire service life shall be taken into account in substantiation of the iodine filter type for the ventilation systems in the NPP design.
3.5.4. Design of the filters shall prevent desorption of iodine from the filters, or desorption shall be taken into account in substantiation of the selected type and class of filters with due regard for iodine forms.
3.5.5. The service life for aerosol and iodine filters shall be determined according to increase of the filter air flow resistance up to the limits specified in the design or according to the g-radiation dose rate from radioactive substances accumulated in the filter. The service life of iodine filters shall be also determined according to maintenance of their absorptive capacity.
3.5.6. Design of filters or materials used for their manufacturing shall eliminate any impact of increased moisture content in the filtered air on aerosol and iodine collection efficiency in all design NPP operation modes.
3.5.7. Materials used to manufacture aerosol filters shall be resistant to vapors of organic solvents.
3.5.8. Impact of increased (in comparison with the working values) temperatures on aerosol filters and sorbents shall not result in any release of toxic substances.
3.5.9. Materials used to manufacture aerosol filters and sorbents for iodine filters shall not be susceptible to thermal decomposition under design NPP operating conditions.
3.5.10. Aerosol filters and materials used for their manufacturing shall comply with the requirements for the class of "low-combustible materials" in accordance with the national standard on fire and explosion hazard of substances and materials.
3.5.11. Design of iodine and aerosol filters shall:
3.5.12. The NPP design shall define the methods for processing and (or) final disposal of spent filters and filtering elements dismantled from the ventilation systems.
4. REQUIREMENTS FOR INSTALLATION AND OPERATION OF SAFETY-RELATED VENTILATION SYSTEMS OF NUCLEAR POWER PLANTS
4.1.1. Only filters and sorbents tested for compliance with the requirements of the NPP design on metrologically validated test stands shall be permitted for installation in the safety-related ventilation systems of the NPP.
4.1.2. All filters and sorbents shall have certificates with indication of the parameters determined in the course of testing. Resistance at the nominal flow rate and collection efficiency for the most penetrating particles shall be specified in the certificates of aerosol filters, and collection efficiency for molecular and organic iodine under the parameters corresponding to the operating conditions shall be specified in the certificates of sorbents.
4.1.3. Installation of filters shall eliminate any possibility for air to bypass the filtering element.
4.1.4. Acceptance testing of the ventilation systems shall be performed subsequent to installation or refurbishment of the ventilation system components.
4.1.5. Acceptance testing shall be performed in accordance with specially developed procedures and programs.
4.1.6. Testing procedures for aerosol and iodine filters shall be subject to metrological appraisal.
4.1.7. The following shall be determined in the course of acceptance testing for the ventilation systems:
4.1.8. Arrangements shall be provided in the course of the NPP commissioning in order to prevent accumulation of construction dust in the filters.
4.1.9. The NPP administration shall appoint the person responsible for operation of the ventilation systems.
4.1.10. The ventilation systems shall be operated in accordance with the guidelines developed on the basis of the system design and engineering documentation.
4.1.11. Aerosol and iodine filters intended for purification of ventilation air from radioactive aerosols and iodine shall be registered and accounted in the equipment owner organization. The person responsible for operation of the ventilation systems and appointed by the NPP administration shall be in charge of accounting. In this case the results of acceptance testing arranged in accordance with par. 4.1.4 shall be documented, and regular verifications of the filter characteristics with documentation of their results shall be also performed.
4.1.12. Regular verification of characteristics and maintenance of the equipment shall be performed in accordance with the requirements of the NPP design, operation guidelines and testing programs.
4.1.13. Maintenance of the ventilation systems shall include servicing of all system components particularly aerosol and iodine filters, fans, valves, air ducts, etc.
4.1.14. Maintenance and verification of the ventilation system equipment characteristics after any accident at the NPP shall be mandatory.
4.1.15. The report with indication of the obtained values for the verified parameters shall be issued subsequent to the testing results for the equipment of the ventilation system.
4.1.16. Any ventilation system components that stopped to perform their functions within the scope established in the design shall be restored or replaced within the period of post-accident clean-up.
4.1.17. The NPP administration shall provide for the administrative arrangements and engineering features to be used in dismantling of the filters in order to prevent release of radioactive substances accumulated in the filter to the NPP rooms or to the environment.
4.1.18. The ventilation systems shall be in operable state during the NPP power unit decommissioning. Necessity and duration of operation of the ventilation systems in the course of the NPP power unit decommissioning shall be defined and substantiated in the NPP power unit decommissioning project.
4.1.19. Ventilation equipment contaminated with radioactive substances and not subject to decontamination shall be handled in accordance with the safety requirements for handling of solid radioactive wastes and also with the requirements of the operation documentation.
4.2. Requirements for control of safety-related ventilation systems of nuclear power plants
4.2.1. The following parameters shall be controlled during operation of the ventilation system filters:
4.2.2. Scope and frequency of control for the parameters of the ventilation systems shall be defined in the NPP design.
4.2.3. Operation limits with regard to resistance of the filters and air flow rate through the filters shall be established for the air filtration systems.
4.2.4. Control means for the parameters of the ventilation systems shall ensure generation of alarms upon any parameter reaching the established limit.
4.2.5. Upon any parameter reaching the established limit it is necessary to detect the cause of any changes in the ventilation system functioning and to eliminate it.
4.2.6. Technical methods and means of control for the parameters of the ventilation systems shall ensure the required measurements within all their potential change ranges.
4.2.7. The scope of radiological control in the ventilation systems shall be determined in the NPP design in accordance with the Sanitary rules for design and operation of nuclear power plants.
4.2.8. Radiological control for the ventilation systems shall include the list of control types, types of radiometric and dosimetric instruments, sampling points and frequency of control.
4.2.9. The control means shall be subject to regular verification in accordance with the requirements of the national standard for metrological support of the NPP operation.
4.2.10. Sampling filters used to control collection efficiency of the filtration systems shall have collection efficiency values exceeding the values for the verified systems.
4.2.11. Sampling devices for control of aerosols shall comply with the isokinetics requirements and shall be located in the places with steady flow along the air duct axis (usually in the end of a straight section).
4.2.12. Selection of the places for monitoring of the ventilation system equipment functioning and control thereof shall be defined and substantiated in the NPP design.
4.2.13. Monitoring of the ventilation system equipment functioning and control thereof shall be arranged:
4.2.14. Control of the parameters shall be provided for the ventilation systems operated during accident and post-accident periods. The scope of control shall be substantiated in the NPP design.