As a result of the GE testing program for the MARK III pressure-suppression containment program, new containment loads associated with a postulated LOCA were identified in 1975 which had not been explicitly included in the original design of MARK I and MARK II containments. These loads resulted from the dynamic effects of drywell air and steam being rapidly forced into the suppression pool during a postulated LOCA event. Other pool dynamic loads previously unaccounted for resulted from the actuation of SRVs in the MARK II containment. The review and evaluation of the MARK I loads were addressed in USI A-7, and SRV loads for all
suppression-type containments were addressed in USI A-39. This item was originally identified in NUREG-0371[1] and was later declared a USI in NUREG-0510.[2]
This USI was RESOLVED with the issuance of NUREG-0808[3] and SRP[4] Section 6.2.1.1C.
[1] NUREG-0371, "Task Action Plans for Generic Activities (Category A)," U.S. Nuclear Regulatory Commission, November 1978.
[2] NUREG-0510, "Identification of Unresolved Safety Issues Relating to Nuclear Power Plants," U.S. Nuclear Regulatory Commission, January 1979.
[3] NUREG-0808, "Mark II Containment Program Evaluation and Acceptance Criteria," U.S. Nuclear Regulatory Commission, August 1981.
[4] NUREG-0510, "Identification of Unresolved Safety Issues Relating to Nuclear Power Plants," U.S. Nuclear Regulatory Commission, January 1979.
Page Last Reviewed/Updated 07/10/2025