During the conduct of a large scale testing program for an advanced design BWR pressure suppression containment system (MARK III), new suppression pool hydrodynamic loads associated with a postulated LOCA were identified which had not been explicitly included in the original design of the MARK I containment systems. These additional loads result from the dynamic effects of drywell air and steam being rapidly forced into the suppression pool (Torus) during a postulated LOCA event. Consequently, it was determined that a reassessment
of the MARK I containment system design would be required. 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 publication of NUREG-0408.[3] All plant-unique analyses and required equipment modifications were reviewed and accepted by the staff and appropriate TS changes were made by the affected licensees.
[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-0408, "Mark I Containment Short-Term Program Safety Evaluation Report," U.S. Nuclear Regulatory Commission, December 1977.
Page Last Reviewed/Updated 06/24/2025