- 89 - EDF has adopted a programme of standardised plant series for the nuclear reactors on its nuclear islands, which enabled it to pool the design studies. The other structures, known as the "site structures" were specifically designed for each site. The nuclear island comprises: The reactor building (BR), containing the reactor and all the pressurised reactor coolant systems, and the containment, A fuel building (BK), housing the new and spent fuel storage and handling facilities, A safeguard auxiliaries and electrical building (BAS/BL), A building for the other nuclear auxiliaries (BAN), An operations building (BW). The site structures include the other buildings and facilities necessary for the operation of the plant, including the heat sink and the intake channel. In general, the design spectra adopted were determined as follows: CP0 and CPY: For the design of the CP0 and CPY plant series, the spectral shape used was that known as the "EDF spectrum", defined as the smoothed mean of eight accelerograms recorded during five earthquakes of Californian origin. The accelerations are normalized according to the local seismicity. P4 and P4: The DBE for Paluel, the first P4 site, was changed during the course of its construction. At the beginning of construction, the spectral shape used hitherto for the units was that of the "EDF spectrum". During construction, a new spectral shape was taken from that established by the Nuclear Regulatory Commission (NRC - nuclear safety regulator in the U.S.A.) in its Regulatory Guide 1.60, which was also adopted in France as the reference for the design of the 1,300 MWe plant series. For the buildings, this led EDF to use the following in turn: o the EDF spectrum normalized to 0.2 g. o for a transitional period, the NRC spectrum normalized to 0.2 g. o the NRC spectrum normalized to 0.15 g. For the following reactors, P4 and P4, EDF adopted the NRC spectrum normalized to 0.15 g with zero period for the standard DBE applicable to nuclear island design, compatible with the sites chosen for the reactors in this plant series. N4: The standard DBE spectrum, applicable for the design of structures and facilities for the N4 plant series, is the NRC spectrum normalized to 0.15 g with zero period. It is normalized to a zero period acceleration of 0.15 g in the horizontal directions and 0.133 g in the vertical direction (which differs from the usual rule which has 2/3 of the horizontal spectrum correspond to the vertical spectrum, and corresponds to 2/3 of an acceleration normalized to 0.2 g. This is a design convention for this plant series). EPR: the DBE is the European EUR spectrum normalized to 0.25 g at zero period. The following table summarises the different design spectra for the nuclear island and site structures: Site Plant series Nuclear island DBE Site structure DBE Bugey CP0 EDF normalized to 0.1 g zero period EDF normalized to 0.1 g zero period Fessenheim CP0 EDF normalized to 0.2 g zero period EDF normalized to 0.2 g zero period, hors BL Blayais CPY EDF normalized to 0.2 g zero period EDF normalized to 0.2 g zero period Chinon CPY EDF normalized to 0.2 g zero period EDF normalized to 0.2 g zero period
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