- 97 - The seismic classification requires justification either by calculation, or by testing on a vibrating table, or through analysis on a case by case basis. The resulting design requirements are proportional to their safety class. For the main primary system, they are defined by the order of 26th February 19747 and for the main secondary system by RFS II.3.88, for all the reactors in service. For level 2 and 3 mechanical equipment, the design requirements and criteria are defined by RFS IV.2.a of 21st December 1984 concerning the requirements to be taken into account in the design of safetyclassified mechanical equipment, carrying or containing a pressurized fluid and classified level 2 or 3. For electrical equipment, the requirements are defined in RFS IV.1.b of 31st July 1985 concerning the design and classification of safety-classified electrical equipment. RFS V.2.g9 defines the acceptable methods for determining all the movements to which the "seismic classified" civil engineering and structures are subjected, on the basis of the seismic motion considered, as well as the corresponding load levels, to allow the design and verification: of the civil engineering strength of these structures subjected to the loads resulting from earthquakes and other actions combined with the earthquakes, of the correct behaviour and performance of the equipment in the facility. Following the adoption of the new RFS 2001-01 concerning the determination of the seismic motion for surface basic nuclear installations, in place of RFS I.2.c dating from 1981, RFS V.2.g was revised to take account of changes to paraseismic engineering know-how (for example, the development of dynamic analyses on detailed 3dimensional models, the improved knowledge of soil behaviour and soil/structure interactions, the development of time-based calculations on advanced models, the incorporation of non-linear phenomena, whether of geometrical or rheological origin) and to ensure consistency with RFS 2001-01. These requirements are included in ASN guide 2-0110. For example, the seismic changes implemented on the occasion of the Fessenheim VD 3, are not due to a reassessment of the seismic hazard, but to the use of new computation methods. In its CSAs reports, EDF recalls that it sets seismic classification requirements for: IPS (important for safety) equipment (defined in the design) and certain non-IPS equipment, on a case by case basis, the PAM (post-accident monitoring) measures, certain equipment required for safety sectorisation, equipment adjacent to a seismic classified system and needed to ensure the isolation between a seismicclassified part and a non-seismic-classified part, equipment containing radioactive materials which, in the event of a leak, could lead to significant releases. Equipment which, if it fell, could lead to the loss of seismic-classified IPS equipment, is the subject of seismic verification (see § Protection against the indirect effects of an earthquake). In the CP0 plant series, about 5,600 equipment items are seismic-classified. In the CPY plant series, about 5,200 equipment items are seismic-classified. In the 1,300 MW plant series, about 8,500 equipment items are seismicclassified. In the N4 plant series, about 9,200 equipment items are seismic-classified. ASN considers that the implementation of this baseline safety requirement by EDF is satisfactory. 7 Order of 26th February 1974 concerning the reactor coolant system (RCS) for pressurised water reactors (PWR) 8 RFS II.3.8 of 8th June 1990 concerning the construction and operation of the main secondary system, for all 900 and 1,300 MWe plant series 9 RFS V.2.g of 31st December 1985 concerning seismic calculations for civil engineering structures 10 ASN Guide 2-01 of 26th May 2006 on taking account of the seismic risk in the design of civil engineering structures for basic nuclear installations
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