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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 46391 | 3 November 2010 13:13:00 | 10 CFR 72.75(d)(1), ISFSI Safety System Functional Failure | Fuel Storage Transfer Cask Neutron Shield Partial Draindown | At 0813 (CDT), the Cooper Nuclear Station (CNS) Control Room (CR) received a report of a partial neutron water shield drain down on the Dry Fuel On-site Transfer Cask (TC). The TC, with a loaded Dry Storage Cask (DSC), was located in the Reactor Building (RB) Railroad Airlock area. Final preparations were being completed prior to transferring the DSC to Horizontal Storage Module (HSM) 2A. The RB and south side of the Administration Building were cleared of unnecessary personnel. No abnormally elevated RB area radiological readings were noted on CR indication. Local indication in the (Railroad) Airlock from portable radiation monitors indicated abnormally high readings due to the drain down. At 0819 (CDT), CNS entered Abnormal Procedure 5.1 RAD, Building Radiation Trouble. Surveys indicate the top of the TC had readings of about 130 mR/hr neutron at 30cm, which is above the normal readings of 2 mR/hr. Surveys of the bottom portion of the TC indicated a neutron dose rate of 10 mR/hr at 30cm. Actions per 5.1 RAD were subsequently performed. An emergency declaration was not required, because no confinement boundary was adversely affected and neutron levels did not meet a factor of 1,000 over normal levels. Since dose rates were no greater than noted above, and because neutron dose was being directed upward due to the shielding loss being in the upper portion of transfer cask, the Technical Support Center (TSC), which is located in the Administration Building, was determined to support habitability. Furthermore the TSC is provided with additional shielding for personnel protection during an event. This is being reported as a 24 hour report under 10 CFR 72.75(d) for an important to safety fuel storage equipment that failed to function as designed when required to prevent releases, prevent exposures in excess of regulatory limits, or mitigate the consequences of an accident and no redundant equipment was available or operable to perform the required safety function. The cause of the drain down is under investigation. The licensee notified the NRC Resident Inspector. |