Document: NUREG-0800
Document ID: eb1d19c1-686c-42f5-ba0a-c417c7b12b8e
Document Type: srp
Title: DC POWER SYSTEMS (ONSITE)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070499.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.2
CFR Part: 
CFR Title: 

Content:
nd components comprising the onsite dc power system must also generally be seismically designed and/or qualified to perform their functions in the event of an earthquake. Meeting this requirement will provide assurance that equipment and structures will be designed to withstand the effects associated with natural phenomena, thus decreasing the probability that seismically- and/or climatology-related natural phenomena could initiate accidents or prevent equipment from performing its safety function during an accident.74 2. Compliance with GDC 4 requires that structures, systems, and components important to safety (a) be designed to accommodate the effects of, and be compatible with, the environmental conditions associated with normal operation, maintenance, testing, and postulated accidents and (b) be appropriately protected against dynamic effects that may result from equipment failures, including missiles. The dc power system is required to provide power to systems important to safety during normal, abnormal, accident, and postaccident conditions. Meeting these requirements will provide assurance that the dc power system will supply electric power required for operation of systems important to safety even if/when subject to adverse environmental conditions and/or dynamic effects.75 3. Compliance with GDC 5 requires that structures, systems, and components important to safety shall not be shared among nuclear power units, unless it can be shown that such sharing will not significantly impair their ability to perform their safety functions, including, in the event of an accident in one unit, an orderly shutdown and cooldown of the remaining units. This criterion requires that component parts of the dc power system not be shared among units without sufficient justification, thereby ensuring that an accident in one unit of a multiple-unit facility can be mitigated using an available compliment of mitigative features, including required dc power, irrespective of