本标准规定了低功率和停机模式下内部和外部危险的1级PRA要求。这些模式包括各种运行状态，从电厂处于远低于标称满功率（低功率）的满功率水平，到电厂在反应堆处于亚临界状态且一次系统减压并充分冷却以进行RHR冷却的情况下关闭的运行状态。在这里，低功率模式仅限于它们是最终导致核电厂停堆的LPSD演变的一部分。 本标准在很大程度上以ASME/ANS RA-Sa-2009为基础，该标准目前仅适用于满功率或接近满功率时的电厂运行状态要求。

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.