Home > NRC Library > Document Collections > General Communications > Information Notices > 1979 > IN 79-26
IN79026 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 November 1, 1979 MEMORANDUM FOR: B. H. Grier, Director, Region I J. P. O'Reilly, Director, Region II J. G. Keppler, Director, Region III K. V. Seyfrit, Director, Region IV R. H. Engelken, Director, Region V FROM: Norman C. Moseley, Director, Division of Reactor Operations Inspection, IE SUBJECT: Information Notice No. 79-26, BREACH OF CONTAINMENT INTEGRITY The subject document is transmitted for issuance on November 5, 1979. The Information Notice should be issued to all power reactor facilities holding operating licenses and construction permits. Also enclosed is a draft copy of the transmittal letter. Norman C. Moseley, Director Division of Reactor Operations Inspection Office of Inspection and Enforcement Enclosures: 1. IE Information Notice No. 79-26 2. Draft Transmittal Letter CONTACT: P. F. McKee, IE 49-28019 . (Transmittal letter for Information Notice No. 79-26 to each holder of an NRC Operating License and Construction Permit.) Information Notice No. 79-26 Addressee: This Information Notice is provided as an early notification of a possibly significant matter. It is expected that recipients will review the information for possible applicability to their facilities. No specific action or response is requested at this time. If further NRC evaluations so indicate, an IE Circular, Bulletin, or NRR Generic Letter will be issued to recommend or request specific licensee actions. If you have questions regarding the matter, please contact the Director of the appropriate NRC Regional Office. Signature (Regional Director) Enclosures: 1. Information Notice No. No. 79-26 2. List of IE Information Notices Issued in the Last Six Months . SSINS: 6870 Accession No: 7908220133 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C. 20555 November 5, 1979 Information Notice No. 79-26 BREACH OF CONTAINMENT INTEGRITY Description of Circumstances: On September 14, 1979, the Consumers Power Company (CPC) notified the NRC of discovery at the Palisades Nuclear Generating Plant of a valve misalignment that had resulted in containment integrity being breached for an indeterminate length of time. While preparing to perform a Type "C" leak test between two manual valves in a 3" bypass line around the main 48" containment purge valve, plant personnel discovered that both of these manual isolation valves were locked in the open position. These valves should have been locked closed. Investigation by the licensee indicated that the valves may have been improperly positioned since April, 1978, when an efficiency test of the bypass line filters was performed. The plant has operated at power for the major portion of that time period. The valve misalignment had no actual impact on the public health. However, in the event of a design basis accident wherein fuel damage and release of primary coolant inside the containment are postulated, the open valves would provide a significant path for a radioactive release from the containment. The initial design purpose for the bypass system was to provide a long term hydrogen control capability for the containment atmosphere following a design basis accident.1 It was intended that after approximately 30 days following an accident, when containment pressure and activity levels dropped sufficiently to permit venting, this system would be manually valved to vent the containment atmosphere, through high efficiency and charcoal filters, to the exhaust stack. Thus the components in the bypass line beyond the two manual isolation valves were not designed for the severe service they would be exposed to with the valves open during the initial pressure surge of the design basis accident, and significant uncontrolled release would result. High radiation in the vicinity of the bypass line would also make immediate closing of the manual isolation valves, even if identified as the source of leakage, an extremely hazardous operation. The principal cause for this event was inadequacy of the procedures addressing proper use and positioning of these valves. The master containment integrity valve line-up checklist, which is performed prior to each startup from cold ________________________________ 1/ Current NRC requirements call for the use of hydrogen recombiners to control hydrogen buildup. Palisades has recombiners installed. . Information Notice No. 79-26 November 5, 1979 Page 2 of 2 shutdown, did not include these valves. The filter efficiency test for the 3" bypass line did not adequately specify the final position of these valves, and this is the probable cause for the valves being left incorrectly positioned. The valve misalignment represents a case where human factors in the form of inadequate procedures resulted in a loss of safety system function. CPC has updated the above mentioned procedures to assure that proper positioning of these valves is addressed. Concurrently, CPC is reviewing other paths from containment to assure that procedures and checklists are complete. CPC has also hired a qualified consultant to perform an independent review for the same purpose. This Information Notice is provided as an early notification of a significant occurrence. It is expected that recipients will review the information for possible applicability to their facilities. No written response is required. If you desire additional information regarding this matter, contact the Director of the appropriate NRC Regional Office. .
Page Last Reviewed/Updated Thursday, March 29, 2012