This issue was identified in NUREG-0471[1] and addressed the concern that additional information was needed on the potential effects of extreme cold weather and ice buildup on the reliability of various plant water supplies. Experience gained during past severe winters indicated that a more thorough understanding of the potential effects of severe ice conditions was necessary to confirm that the design and operation of safety-related water supplies would ensure adequate operation of safety systems. Guidance for the review of licensee submittals regarding ice effects is contained in SRP[2] Section 2.4.7.
The loss of plant water sources (particularly the ultimate heat sink) by ice formation, blockage by ice dams, etc., could impair a plant's core cooling capability during shutdown. This issue affects all plants located in geographical areas in which there has been a history of ice formation, ice jams, ice floes, etc.
The loss of essential service water in LWRs from various causes, including ice effects, was addressed in the evaluation of Issue 153.[3]
[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 C. Ader from K. Kniel, "Request for Prioritization of New Generic Safety Issue `Loss of Essential Service Water in LWRs,'" May 2, 1990. [9704090120]
Page Last Reviewed/Updated 06/24/2025