05000285/LER-2014-005
| Fort Calhoun Station | |
| Event date: | 6-27-2014 |
|---|---|
| Report date: | 8-25-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2852014005R00 - NRC Website | |
Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by Internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
BACKGROUND
Fort Calhoun Station (FCS) is a two-loop reactor coolant system of Combustion Engineering design.
FCS uses custom Technical Specifications (TSs) which define containment integrity as follows:
Containment Integrity Containment integrity is defined to exist when all of the following are met:
(1) All nonautomatic containment isolation valves which are not required to be open during accident conditions and blind flanges, except for valves that are open under administrative control as permitted by Specification 2.6(1)a, are closed.
(2) The equipment hatch is properly closed and sealed.
(3) The personnel air lock satisfies Specification 2.6(1)b.
(4) All automatic containment Isolation valves are operable, locked closed, or deactivated and secured in their closed position (or isolated by locked closed valves or blind flanges as permitted by a limiting condition for operation).
(5) The uncontrolled containment leakage satisfies Specification 3.5, and (6) The sealing mechanism associated with each penetration (e.g., welds, bellows or 0-rings) is operable.
The TS for containment integrity 2.6(1) reads as follows:
a. Containment integrity shall not be violated unless the reactor is in a cold or refueling shutdown condition. Without containment integrity, restore containment integrity within one hour or be in at least hot shutdown within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, in at least subcritical and cold shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. Normally locked or sealed-closed valves (except for PCV- 742A/B/C/D) may be opened intermittently under administrative control without constituting a violation of containment integrity.
EVENT DESCRIPTION
On Friday, June 27, 2014, during performance OP-ST-CCW-3005B "Component Cooling Category A and B Valve Exercise Test (for the C and D valves)" it was discovered that test swagelock plug F1 was found missing between containment penetration M-88 "Containment Purge Inlet (Direct Communicating System)" and PCV-742D "Containment Purge Air Inlet Outboard Isolation Valve.
Instrument and Control (I&C) technicians discovered the test swagelock plug resting on a nearby junction box and not in place on the containment penetration.
l&C technicians immediately notified the Auxiliary Building Operator (NSOA) who was assisting with the CCW surveillance test. Operations shift supervision were notified and operations declared containment inoperable per Technical Specification 2.6(1)a and entered a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> LCO to restore Fort Calhoun Station 05000285 Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by Internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
containment integrity. Additionally, operations entered AOP-12 "Loss of Containment Integrity". The shift manager directed l&C technicians to reinstall the test swagelock plug Fl on containment penetration M-88. At that point, operations declared containment operable and exited the associated Technical Specification 2.6(1)a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> LCO. Additionally, operations met exit conditions for AOP-12 and exited that procedure.
Operations shift supervision directed investigation of other outboard containment penetrations in rooms 81, 69, 59 and 13. This investigation revealed that all containment penetrations were found to be acceptable and no other missing test swagelock plugs were discovered. At that time operations reported no extent of condition existed. Condition Report 2014-07958 documents this issue. This event is reportable as a loss of containment integrity under 10 CFR 50.73(a)(2)(i)(B).
CONCLUSION
Maintenance supervision determined that the last time penetration M-88 and its associated test swagelock plug Fl was manipulated was during the most recent local leak rate test (LLRT) for this penetration.
Following valve maintenance during an extended shutdown, on 11-22-13 contract l&C personnel performed an "As-Left" containment penetration LLRT using procedure IC-ST-AE-3188, "Type C Local Leakage Rate Test of Penetration M-88." A clearance was hung by operations personnel in support of the LLRT to control penetration dampers PCV-742C, "Containment Purge Air Inlet Inboard Isolation Valve," and PCV-742D. The LLRT test was completed as required and met the leakage criteria. During restoration of the penetration, procedure IC-ST-AE-3188 step 7.4.3 requires l&C technicians to reinstall cap F1 onto fill point and tighten. This step has an independent verification required. Both technicians initialed that the cap was reinstalled and independently verified.
A cause analysis determined that:
FCS maintenance personnel exhibited weak Human Performance tool Independent Verification usage.
And FCS personnel completed 01-CO-5, "Containment Integrity," checklists prior to all containment isolation boundary maintenance and/or LLRTs being completed.
CORRECTIVE ACTIONS
The Swagelock cap that was missing has been reinstalled and the system is now fully operable.
Investigation into other containment penetrations in rooms 81, 69, 59, and room 13 found no extent of condition. Additional actions will be implemented by the stations corrective action system.
SAFETY SIGNIFICANCE
Fort Calhoun Station Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by Internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
At the time of this event, the unit was at various power levels, but RCS temperature remained> 210°F requiring containment integrity per Technical Specification 2.6.1(a) for 151 days while containment penetration M-88 fill plug cap F-1 was not installed.
During this time, PCV-742C and PCV-742D remained locked closed. No pathway ever existed from the containment atmosphere through the inboard isolation valve PCV-7 42C through the open penetration fill plug opening during this time period.
SAFETY SYSTEM FUNCTIONAL FAILURE
This does not represent a safety system functional failure in accordance with NEI 99-02, revision 7.
PREVIOUS EVENTS
No incidents of loss of containment integrity due to human error have been documented in the last three years.
Fort Calhoun Station 05000285