- 28 - (SEPTEN) for interpretation. However, the Nogent NPP demonstrated its ability to interpret these data during the course of an unannounced exercise initiated by ASN. ASN finds that the staff liable to have to collect and analyse the data indicating the characteristics of an earthquake, in particular those in charge of operating the reactor, need to be trained in the use of the instrumentation and in particular the reading of the values given by the control room peak accelerograph. Resistance of equipment and buildings EDF internal technical directive DT 320 concerning the inventory per reactor of the equipment nonconformities still not closed, requires that by 1st July 2011 the sites: create and then keep an up-to-date list of uncorrected equipment nonconformities comprising deviations that are; o generic and not yet closed on the reactor; o local, leading to a significant safety-related event (ESS) and to a significant event report and not yet closed on the unit. be able to provide this list at all times. Several sites were unable to present this list and identify the nonconformities, which is liable to have an impact on seismic risk management. The inspectors observed that in certain cases, when this list was available, there was no safety analysis of nonconformity combinations (Nogent, Penly for example). ASN finds that EDF must keep this list up-to-date (defined according to DT 320) and analyse nonconformity combinations on each of its reactors. 2.2.3 Instrumentation Operating basis earthquake (OBE) values The EDF head office departments issued an internal memo setting out the OBE values to be considered in the reactor control system. The acceleration values to be considered for the OBE may differ between the documents used by the sites (operating instructions, safety report). Earthquake: justification of site classification The studies conducted by EDF showed that the geology of the Dampierre site is heterogeneous; the seismic instrumentation will therefore be completed in 2013 and 2014. The site is at present unsure of whether the values given by the sensors are underestimates or overestimates. An earthquake bigger than the operating basis earthquake might therefore not be detected and not lead to shutdown of the units. RFS I.3.b (§ 2.2.3) states that classification of a site as "homogeneous" must be justified by the licensee. Failing which, the site is classified as "heterogeneous". This classification then determines the instrumentation with which the site is to be equipped. The Penly and Flamanville sites presented no evidence to justify the applicable category. Equipment condition The facility visits and examination of the maintenance reports revealed discrepancies in the manual of instructions for maintaining qualification (RPMQ) for accident conditions: the EDF national frame of reference requirements stipulate that for the seismic accelerometers, four screws must attach the sensor to the ground, with a tightening torque of 0.7 daN.m. The inspectors however found on various sensors that unit mounting screws were missing (Nogent, Cattenom, Blayais), mounting screws were rusted (Nogent, Paluel) and the tightening torques on the four ground mounting screws had not been checked; similarly, EDF national frame of reference requirements stipulate that for the peak accelerographs, the four mounting screws between the sensor and the ground must be torqued to 0.5 daN.m. The inspectors found that mounting screws were corroded on the Nogent and Golfech sites; some sites did not incorporate the RPMQ requirements into their local procedures (Blayais).
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