Peach Bottom: Cask Leakage Rate Greater than Specification

Facility: PEACH BOTTOM Event Date: 10/22/2010 SPENT FUEL STORAGE RELATED DEFECT - CASK LEAKAGE RATE GREATER THAN TECHNICAL SPECIFICATION "On 10/22/10, at 1058 EDT, a troubleshooting of Independent Spent Fuel Storage Installation (ISFSI) Cask TN-50-A indicated that a leak existed in the cask lid sealing area at a rate greater than allowed by ISFSI Cask Technical Specification (TS) Section 3.1.3, Cask Helium Leak Rate. TS 3.1.3 limits the Cask Helium Leak Rate to 1.0 E-05 ref-cc/sec. The cask is currently in unloading operations and is located within the Peach Bottom Atomic Power Station Unit 3 containment building. Preliminary review indicates that a leak exists at the weld plug that provides sealing of the drilled interseal passageway associated with the drain port penetration of the cask lid. This leak effectively provides a bypass of the main lid outer confinement seal. "This report if being submitted pursuant to 10CFR72.75(c)(1) as a result of a material defect in a weld in the cask main lid. This report is also being submitted pursuant to 10CFR72.75 ® (2) as a result of a resolution in the effectiveness of the cask confinement system. "The Certificate of Compliance for this cask is 1027 (Amendment 1). "The NRC Resident Inspector has been informed of this notification."