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SSG-54
Accident Management Programmes for Nuclear Power Plants
Footnotes
1INTERNATIONAL ATOMIC ENERGY AGENCY, Severe Accident Management Programmes for Nuclear Power Plants, IAEA Safety Standards Series No. NS-G-2.15, IAEA, Vienna (2009).
2A ‘long term safe stable state’ is a plant state following an anticipated operational occurrence or accident conditions in which the reactor is subcritical and the fundamental safety functions can be ensured to be in and can be maintained in a stable condition for a long time.
3In this Safety Guide, the term ‘accident management guidance’ is used to cover both EOPs and SAMGs. Paragraphs 2.42–2.55 elaborate on the differences between EOPs and SAMGs.
4For CANDU reactors, the equivalent objective is to maintain the integrity of pressure tubes and calandria tubes.
5An example of a preventive strategy is ‘feed and bleed’ to depressurize the reactor pressure vessel and ensure cooling of the core. Another example is the use of non-permanent equipment during a prolonged station blackout caused by an external hazard.
6‘Non-permanent equipment’ is portable or mobile equipment that is not permanently connected to the plant and is stored in an on-site or an off-site location.
7EOPs are also used in the mitigatory domain in some plants, especially in the early phase of a severe accident, for actions initiated from the main control room before the technical support centre is functional.
8For example, in some States a mean annual frequency is considered that is at least one order of magnitude greater than the probability of accidents considered in the design.
9Reasonable confidence that there exists a quantifiable positive margin to equipment failure can be obtained through evaluation based on available information coming from different sources or complementary tests or analysis.
10Such assessment is sometimes referred to as an assessment of the ‘survivability’ of the equipment or instrumentation.
11A ‘tabletop exercise’ is a structured discussion exercise undertaken by decision makers or responders that is based on a scenario or set of conditions representing a potential emergency response situation. The objective is both educational and developmental in that misunderstandings, incorrect perceptions and errors in procedures can be identified easily and then corrected.
12In some States, the transfer of responsibility for emergency response to the authorized person occurs when this person arrives at the emergency response organization in all cases, irrespective of severity of the accident. Also, in some States the authorized persons (or their replacements) will retain decision making authority until a long term safe stable state is achieved
13 Many categorization schemes are possible. SSG-4 [24] contains such categorization schemes for Level 2 PSA.
France1The terminology used in the examples in this annex is based on the specific terminology used in each State.
2In the case of the European Pressurized Reactor, additional dedicated valves are provided for this purpose.
3Activation of the containment spray system may be requested by the emergency response team when deemed appropriate (essentially for preventing unacceptable de-inertization of the containment atmosphere); it also leads to the flooding of the reactor pit.
4This action limits the risk of hydrogen combustion in very specific situations.
Japan1The use of ‘shall’ in this annex is to be understood to imply a national regulatory requirement rather than a safety requirement of the IAEA.
Tags applicable to this publication
- Publication type:Specific Safety Guide
- Publication number: SSG-54
- Publication year: 2019