05000285/LER-2015-001, Inadequate Design of High Energy Line Break Barriers

LER-2015-001, Inadequate Design of High Energy Line Break Barriers

Fort Calhoun Station
Event date:	9-30-2013
Report date:	3-27-2015
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
2852015001R00 - NRC Website

On January 28, 2015, following a station initiated review of operability evaluations, it was determined that a penetration with inadequate jet impingement protection had been previously identified as part of station extent of condition reviews and constituted an unanalyzed condition, but, had not been reported as required. This issue was discovered during an extent of condition review of high energy line break issues that the station initiated due to previously identified concerns. This issue and the other issues identified during the extent of condition review were corrected prior to plant heatup.

The Shift Manager that approved the operability evaluation believed that the reportability aspect of the penetration had been previously reported to the NRC and that no further report was required. The Shift Manager did not confirm that the reportability had been completed under another LER.

These issues were discovered during the Electrical Environmental Qualification Program Reconstitution Project. The deficiencies were discovered during extent of condition reviews. The deficiencies were properly remediated prior to plant startup in December 2013.

BACKGROUND

Fort Calhoun Station (FCS) is a two-loop reactor coolant system of Combustion Engineering design.

EVENT DESCRIPTION

On January 28, 2015, following a station initiated review of operability evaluations, it was determined that inadequate jet impingement protection for a penetration with an inadequate seal had been previously identified as part of station extent of condition reviews. This constituted an unanalyzed condition that had not been previously reported as required. The condition was initially identified on September 30, 2013. The station was shutdown and cooled down in mode 5 (refueling shutdown) at the initial time of discovery. The degraded condition was discovered during an extent of condition review of high energy line break (HELB) issues at the station initiated due to previously identified concerns. This issue and the other issues identified during the extent of condition review were corrected prior to plant heatup.

This report is being submitted pursuant to 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition.

CONCLUSION

The station has reported several issues to the NRC concerning HELB issues identified at the station.

These LERs include, 2012-009 (Inoperable Equipment due to Lack of Environmental Qualifications), 2012-015 (Electrical Equipment Impacted by High Energy Line Break Outside of Containment), 2012-017 (Containment Valve Actuators Design Temperature Ratings Below Those Required for Design Basis Accidents), 2013-011 (Inadequate Design for High Energy Line Break in Rooms 13 and 19 of the Auxiliary Building), 2013-015 (Unqualified Coating Used as a Water Tight Barrier in Rooms 81 and 82), 2013-016 (Reporting of Additional High Energy Line Break Concerns) and 2014-004 (Unqualified Limit Switches Render Safety Equipment Inoperable).

The Shift Manager that approved the Operability Evaluation believed that the reportability aspect of the penetration had been previously reported to the NRC and that no further report was required. The Shift Manager did not confirm that the reportability had been completed under another LER.

Portions of the HELB barrier between room 81 (steam and feed line room) and room 56 (switchgear room) were found degraded. Specifically, several areas under the main steam and feedwater lines in room 81 lacked adequate protection from jet impingement. These areas included penetration 557 and several small areas of the floor in room 81. The floor slab in room 81 is the ceiling of room 56.

CORRECTIVE ACTIONS

The degraded jet impingement barriers were discovered as part of the extent of condition reviews for the Electrical Environmental Qualification (EEQ) Program Reconstitution Project. The deficiencies were properly remediated prior to plant startup in December 2013. All other HELB issues found as part of the extent of condition reviews were reviewed and no other cases of failing to report events were identified.

SAFETY SIGNIFICANCE

Jet impingement protection did not meet the requirements for proper HELB mitigation. As a result, some equipment may have been impacted during potential high energy line breaks in room 81. Room its function for those HELBs that resulted in jet impingement directly on the degraded portion of the barrier. Under these conditions, a postulated HELB had the potential to impact the ability of safety systems to respond to the accident.

SAFETY SYSTEM FUNCTIONAL FAILURE

This does not represent a safety system functional failure in accordance with NEI 99-02, revision 7.

PREVIOUS EVENTS

2012-009 (Inoperable Equipment due to Lack of Environmental Qualifications), 2012-015 (Electrical Equipment Impacted by High Energy Line Break Outside of Containment), 2012-017 (Containment Valve Actuators Design Temperature Ratings Below Those Required for Design Basis Accidents), 2013-011 (Inadequate Design for High Energy Line Break in Rooms 13 and 19 of the Auxiliary Building), 2013-015 (Unqualified Coating Used as a Water Tight Barrier in Rooms 81 and 82), 2013-016 (Reporting of Additional High Energy Line Break Concerns) and 2014-004 (Unqualified Limit Switches Render Safety Equipment Inoperable) Fort Calhoun Station 05000285