05000325/LER-2014-002
| Brunswick Steam Electric Plant (Bsep) Unit 1 | |
| Event date: | 03-09-2014 |
|---|---|
| Report date: | 05-05-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3252014002R00 - NRC Website | |
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
Introduction Initial Conditions At the time the event occurred, Unit 1 was in Mode 5 at zero percent rated thermal power, Secondary containment [NG] was removed from service, and the guidance of Enforcement Guidance Memorandum (EGM) 11-003, Revision 2, "Dispositioning Boiling Water Reactor Licensee Noncompliance with Technical Specifications Containment Requirements During Operatic s with a Potential to Drain the Reactor Vessel," was being followed per plant procedure.
Reportability Criteria This event is reportable per 10 CFR 50.73)(a)(2)(i)(B) as c condition prohibited by the plant's Technical Specifications (TS). Leading up to this event, secondary containment was removed from service while operations with potential to drain the reactor vessel (OPDRVs) were in progress. This is permitted by EGM 11-003 if certain conditions are met. Action 4 of EGM 11-003 says that all other TS requirements involving OPDRVs must be satisfied, and if the TSs are more restrictive than EGM 11-003 guidance, then the TSs must be followed. TS Limiting Condition for Operation (LCO) 3.6.4.2 requires secondary containment isolation dampers (SCIDs) to be operable during OPDRVs. Per the guidance in EGM 11-003, the SCIDs must remain operable during OPDRVs even if the secondary containment has been properly removed from service. At the time of the event, one train of SCIDs was being supplied by temporary electric control power rather than by normal or emergency electric control power. Per the TS definition of operability, either normal or emergency power is required for operability. Without either of these, the affected SCIDs were declared inoperable. The Required Actions of LCO 3.6.4.2 for inoperable SCIDs were not carried out within the Completion Times; therefore, the plant entered a condition prohibited by the TS, and the event is reportable per 10 CFR 50.73(a)(2)(i)(B).
Event Description
On March 9, 2014, Unit 1 was in Mode 5 with the reactor vessel disassembled, water level equalized with the spent fuel pool (SFP), SFP gates removed and a refueling outage underway.
As part of normal outage maintenance activities, leakage was identified from valves connected to the reactor coolant system [AD]. The leakage was classified as an OPDRV. Outage plans called for work to be performed on a main steam [SB] isolation valve, which rendered the secondary containment inoperable when the valve was disassembled. With OPDRVs ongoing and secondary containment planned to be made inoperable, actions were taken to comply with EGM 11-003.
Concurrent with these activities, planned electrical bus work began, which later resulted in removing the normal and emergency control power supplies for one train of SCIDs, rendering them inoperable.
Temporary electrical control power was supplied to the SCIDs because involved personnel mistakenly believed temporary control power was satisfactory since it would provide the SCIDs with the capability to perform their function.
I Event Description (continued) The next shift of Operations personnel questioned whether the temporary power satisfied the requirements for TS operability of the SCIDs and determined that it did not. Subsequently, actions were taken to isolate leakage paths from the reactor, exiting the OPDRV condition by 0453 EDT on March 10, 2014. When OPDRVs were halted, TS compliance was restored.
Event Cause This event resulted from a procedural deficiency. The temporary power procedure, OMMM-054, "Temporary Power Feed Documentation," does not require an operability decision by a licensed Senior Reactor Operator (SRO) before determining what process will be used to supply temporary power. A contributing cause was that related procedure OSMP-DMPOO2, "Tie-In of Unit 1 Temporary Power Loads During Division 1 and Division 2 Bus Outages," also fails to state that supplying SCIDs with temporary power could make them inoperable; therefore, in this event, temporary power was applied to SCIDs to maintain their functionality. This condition was erroneously accepted in lieu of a formal review for operability by a licensed individual. This resulted in the temporary power being credited for operability of the SCIDs.
Safety Assessment The safety significance of this event is minimal. The sole nuclear safety function of the SCIDs is to support secondary containment operability. However, the secondary containment was properly removed from service throughout the event, and the compensatory measures of EGM 11-003 were properly implemented, except for maintaining SCID operability. In addition, temporary control power was sourced from a safety-related electrical bus, though not through a qualified connection. This maintained the capability for the SCIDs to perform their function, but they were not considered operable per the Technical Specifications. Consequently, this event had no adverse impact on nuclear safety.
Corrective Actions
Any changes to the corrective actions and schedules noted below will be made in accordance with the site's corrective action program.
Procedures OMMM-054 and OSMP-DMP002 will be revised by August 6, 2014, to include review by a Senior Reactor Operator and to state that temporary power supplies installed without the use of a formal design process cannot be credited for operability.
Previous Similar Events
Previously submitted LERs and the site's corrective action program database were reviewed for the past three years to identify any previous similar events in which components were erroneously relied on for operability. An event was reported via LER 1-2012-006, dated November 19, 2012, in which a seal on a reactor recirculation system pump was being replaced. The pump's isolation valve had minor leakage, Previous Similar Events (continued) which was not identified as an OPDRV. The corrective action for that event was to revise procedure 001-01.01, "Conduct of Plant Operations Supplement," to clarify the conditions when the plant must be considered to be in an OPDRV. That corrective action addressed when the guidance of EGM 11-003 should be applied and could not reasonably have been expected to prevent this event.
Commitments No regulatory commitments are contained in this report.