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Safety of Nuclear Fuel Cycle Facilities

SSR-4

Safety of Nuclear Fuel Cycle Facilities

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SSR-4

Safety of Nuclear Fuel Cycle Facilities

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Footnotes
1INTERNATIONAL ATOMIC ENERGY AGENCY, Safety of Nuclear Fuel Cycle Facilities, IAEA Safety Standards Series No. NS-R-5 (Rev. 1), IAEA, Vienna (2014).
2See Definitions.
3For nuclear fuel cycle facilities, this is the operating organization.
4See Requirement 21 and Definitions.
5See Definitions.
6See Requirements 23, 27 and 28 of GSR Part 1 (Rev. 1) [3].
7The IAEA issues guidance on nuclear security in the IAEA Nuclear Security Series.
8Although the utilization and modification of nuclear fuel cycle facilities are activities that are normally included under operation, in some cases they are considered separate stages in the authorization process, since their safety implications give rise to a large amount of review and assessment activities that are repeated a number of times over the lifetime of the facility (see Requirement 5).
9Independent assessments such as audits or surveillance are carried out to determine the extent to which the requirements for the management system are met, to evaluate the effectiveness of the management system and to identify opportunities for improvement. They can be conducted by or on behalf of the organization itself for internal purposes, by interested parties such as customers, by the regulatory body (or by other persons on its behalf), or by independent external organizations.
10Senior management is the person or group assigned by the organization that directs, controls and assesses an organization at the highest level [7].
11This system integrates all elements of management, including safety, health, environmental, security, quality, human-and-organizational-factor, societal and economic elements, so that safety is not compromised.
12In this publication, approval can be mean either approval by the management of the operating organization or approval by the regulatory body, unless otherwise specified.
13In this publication, administrative controls are instructions for modifying the actions of individuals and groups of personnel for the purposes of maintaining or enhancing safety
14The membership of the safety committee may differ with facility type and the chairperson could be the facility manager
15In some States a different advisory group (or another safety committee) is established to advise management of the operating organization on the safety aspects of the day-to-day operation of the facility.
16In this publication, the radiological and associated chemical or toxicological impact on the environment are collectively termed the ‘environmental impact’.
17An early release of radioactive material is a release of radioactive material for which off-site protective actions are necessary but are unlikely to be fully effective in due time; a large release of radioactive material is a release of radioactive material for which off-site protective actions limited in terms of times and areas of application are insufficient for protecting people and the environment.
18See Definitions.
19Systems and characteristics in nuclear fuel cycle facilities differ from those in nuclear reactors, and the separation of safety systems from systems for normal operation is one of the principal means of avoiding common mode failures. Any use of systems that provide safety functions as primary systems for normal operational control requires justification. See Requirement 10 and Definitions.
20The possibility of certain conditions occurring is considered to have been practically eliminated (i.e. eliminated from further consideration) if it is physically impossible for the conditions to occur or if the conditions can be considered with a high level of confidence to be extremely unlikely to arise.
21Such conditions include facility states resulting in off-site radiological consequences that exceed the contamination level or radiation level criteria for a design basis accident.
22This does not override the need for safety to be enhanced by the use of new or improved designs and technology, subject to appropriate qualification, testing and safety analysis.
23Items important to safety may be classified in different ways (e.g. seismic or environmental qualification, or quality categorization) and in two or more levels, or a simpler binary ‘safety’ and ‘non-safety’ classification may be used for all items in the nuclear fuel cycle facility. See also Requirement 17.
24Including conditions that are referred to as credible abnormal conditions.
25Best estimate criteria are used for design extension conditions, see para. 6.73.
26In some States the term ‘target’ is used rather than ‘constraint’.
27Including accident conditions with no off-site impact but having the potential to harm personnel.
28Effects of extreme loads include:
  • Distortion of containers for fissile material;
  • Rainwater ingress to buildings in which nuclear material is handled;
  • The effects of wind pressure on tower cranes used to lift nuclear material or waste;
  • The effect of pressure surges on high efficiency particulate air (HEPA) filters, caused by escaping gases;
  • Inaccurate or zero readings from instruments (e.g. radiation detectors) that are in fact off the scale.
29See also Requirements 30 and 44.
30Including the accidental addition of moderator or the inadvertent mixing of incompatible, hazardous or reactive chemicals or radioactive material.
31See also Requirement 26.
32Including items essential to the maintenance of criticality safety and items used to lift spent fuel and breeder elements in pools.
33In some systems or parts of systems, the direction of airflow or the absence of any airflow may be determined by other factors, e.g. the need to prevent ingress of oxygen or for pressurized vessels or locally pressurized systems. Where flammable materials are processed, inert gases may be used instead of air to provide the required flows.
34The objective is the optimization of protection; for example, increased automation may increase the exposure of maintenance staff at the same time as reducing the exposure of operators. The total exposure could increase, especially if the automation is unreliable.
35These may be different process streams and samples for each facility state.
36It will instead be necessary to demonstrate that the material itself cannot sustain a nuclear chain reaction or that the maximum quantity of fissile nuclides involved are far below the relevant minimum critical parameters (guidance on various aspects of criticality control is provided in IAEA Safety Standards Series No. SSG-27, Criticality Safety in the Handling of Fissile Material [16]).
37See also Requirements 22 and 23.
38i.e. whether the compressed air system is open or closed.
39Including non-permanent equipment stored off the site.
40Although commissioning is the principal means of ensuring that the facility meets the design intent, a number of States also place a high reliance on documentary evidence, e.g. the review of as built documents and other quality assurance documentation such as X ray or other non-destructive testing records for welding, to demonstrate, in particular, the establishment of the first level of defence in depth, as far as practicable.
41Tests carried out in the construction stage may also be included in cold commissioning, in accordance with national regulations. For some facilities, a ‘warm’ or ‘trace active’ commissioning stage may be added.
42Including discharges of volatile fission products.
43In some States a different advisory group (or another safety committee) is established to advise the facility manager on the safety aspects of the day-to-day operation of the facility.
44This is also called knowledge management (see also Requirement 62).
45In this context, personnel may be authorized by the operating organization, or by the regulatory body if required by national regulations.
46Limiting conditions for safe operation can also be applied for situations that are not accident conditions. For instance, a lone operator handling fissile material is not an accident condition, but could be prevented by the limiting conditions for safe operation for the facility.
47For example, training may be developed using the records and reports generated at the nuclear fuel cycle facility (Requirement 62).
48In this context, personnel may be authorized by the operating organization, or by the regulatory body if required by national regulations.
49See Requirement 5.
50Typically by measurement of gamma rays or neutron particles.
51For example, a drop in voltage may cause devices to fail at different times.
Risk Criteria for Nuclear Fuel Cycle Facilities
1INTERNATIONAL ATOMIC ENERGY AGENCY, Safety Classification of Structures, Systems and Components in Nuclear Power Plants, IAEA Safety Standards Series No. SSG-30, IAEA, Vienna (2014).
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Tags applicable to this publication

  • Publication type:Specific Safety Requirements
  • Publication number: SSR-4
  • Publication year: 2014
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