ANS 58.22-2014 - Requirements for Low Power and Shutdown Probabilistic Risk Assessment - ANS/ASME-58.22-2014 (Trial Use Standard)
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This standard establishes requirements for a Level 1 PRA of internal and external hazards for low power and shutdown modes. These modes include operating states ranging from those in which the plant is at full power levels substantially below nominal full power (low power) to operating states in which the plant is shutdown with the reactor subcritical and the primary system depressurized and cooled sufficiently to be placed on RHR cooling. Here the low power modes are included only to the extent that they are part of LPSD evolutions eventually leading to plant shutdown. This standard bases these requirements in large part on ASME/ANS RA-Sa-2009, which at present is restricted to requirements for plant operating states at or near full power.