Offsite power system frequency decay, depending on the rate of decay, could provide an electrical brake on the reactor coolant pump motors that could slow the pumps faster than the assumed flywheel coastdown flow rates normally used in analyzing loss of flow accidents. Item A-35, "Adequacy of Offsite Power Systems," will determine a maximum credible frequency decay rate to be used in this task. This NUREG-0471[1] task will determine if any additional measures are necessary to protect against a frequency decay event.
BTP ICSB-15, which addressed this issue, was deleted in Revision 2 to SRP[2] Appendix 8A in July 1981. A PSB memorandum[3] was issued to GIB on July 31, 1981 describing the basis for this resolution. Based on this SRP change, DSI concluded that no further action on this issue was required.[4],[5] Thus, this issue has been RESOLVED.
[1] NUREG-0471, "Generic Task Problem Descriptions (Categories B, C, and D)," U.S. Nuclear Regulatory Commission, June 1978.
[2] NUREG-0800, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants," U.S. Nuclear Regulatory Commission, (1st Ed.) November 1975, (2nd Ed.) March 1980, (3rd Ed.) July 1981.
[3] Memorandum for K. Kniel from M. Srinivasan, "Generic Issues Tracking System (GITS) B-70; Power Grid Frequency Degradation and Effect on Primary Coolant Pumps," July 31, 1981. [8109140246]
[4] Memorandum for S. Boyd from M. Srinivasan, "FY 1983FY 1984 Office of Nuclear Reactor Regulation Operating Plan," November 17, 1982. [8301100332]
[5] Memorandum for W. Minners from R. Mattson, "Schedules for Resolving and Completing Generic Issues," January 21, 1983. [8301260532]
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