Resolution of Generic Safety Issues: Item A-6: MARK I Short-Term Program (Rev. 2) ( NUREG-0933, Main Report with Supplements 1–35 )

DESCRIPTION

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 0371² and was later declared a USI in NUREG-0510.¹⁸⁶

CONCLUSION

This USI was RESOLVED with the publication of NUREG-0408.⁷⁰¹ 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.

REFERENCES

0002. NUREG-0371, "Task Action Plans for Generic Activities (Category A)," U.S. Nuclear Regulatory Commission, November 1978. 0186. NUREG-0510, "Identification of Unresolved Safety Issues Relating to Nuclear Power Plants," U.S. Nuclear Regulatory Commission, January 1979. 0701. NUREG-0408, "Mark I Containment Short-Term Program Safety Evaluation Report," U.S. Nuclear Regulatory Commission, December 1977.