Resolution of Generic Safety Issues: Item A-7: MARK I Long-Term Program (Rev. 2) ( NUREG-0933, Main Report with Supplements 1–34 )
During testing for an advanced BWR containment system design (MARK III), suppression pool hydrodynamic loads were identified which had not been considered in the original design of the MARK I containment system. To address this issue, a MARK I Owners’ Group was formed and the assessment was divided into a short-term and a long-term program. The results of the NRC staff's review of the MARK I Containment Short-Term Program were documented in NUREG-0408.701 The long-term program was conducted to provide a generic basis to define suppression pool hydrodynamic loads and the related structural acceptance criteria, such that a comprehensive reassessment of each MARK I containment system could be performed.
A series of experimental and analytical programs were conducted by the MARK I Owners’ Group to provide the necessary bases for the generic load definition and structural assessment techniques. The generic methods proposed by the MARK I Owners’ Group, as modified by the NRC staff's requirements, were to be used to perform plant-unique analyses which would identify the plant modifications, if any, needed to restore the originally intended margin of safety in the MARK I containment designs. This item was originally identified in NUREG-03712 and was later declared a USI in NUREG-0510.186