05000331/LER-2014-006
| Duane Arnold Energy Center | |
| Event date: | 10-12-2014 |
|---|---|
| Report date: | 12-9-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3312014006R00 - NRC Website | |
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I. Description of Event:
On October 12, 2014, while in Mode 5 for a refueling outage (RFO 24), Duane Arnold Energy Center (DAEC) implemented the guidance of NRC EGM 11-003, Revision 2, "Enforcement Guidance Memorandum 11-003, Revision 2, Dispositioning Boiling Water Reactor Licensee Noncompliance with Technical Specification Containment Requirements during Operations with a Potential for Draining the Reactor Vessel." This was prior to beginning a series of planned maintenance activities replacing four Local Power Range Monitors (LPRMs) which provide input on reactor core power to the control room and plant safety systems. Each of these actions was considered an Operation with a Potential for Draining the Reactor Vessel (OPDRV) due to the need to access the vessel interior via inlets on the bottom of the vessel.
Plant Technical Specification 3.6.4.1 requires Secondary Containment operability while in Mode 5 with OPDRV actions in progress. As an alternative, the NRC has issued EGM 11-003, Revision 2, which provides generic enforcement discretion following implementation of specific interim actions as an alternative to full compliance with this technical specification. These interim actions require water level in the reactor vessel to be of sufficient depth to ensure that a vessel drainage event related to the OPDRV activities will not result in insufficient inventory for at least twenty four hours, assuming no compensatory actions are taken. In addition, the EGM interim actions require the capability of isolating the OPDRV leakage path (through valve closure, etc.). Also required is the availability of a safety-related pump with an extensive makeup water source, and multiple independent means of determining water level in the reactor vessel.
On October 12, components providing Secondary Containment at DAEC were not functional while undergoing scheduled maintenance. As planned, prior to commencing OPDRV activities for LPRM replacement, plant personnel confirmed and documented that the interim conditions and actions required by EGM 11-003 were in place. Beginning on October 12, 2014 at 1500, NRC Enforcement Guidance Memorandum (EGM) 11-003, Revision 2 for the performance of OPDRVs was invoked. LPRM replacements were completed at 0320 on October 13, 2014. Secondary Containment was successfully restored to operability on October 13, 2014 at 1805, at which time EGM 11-003 Revision 2 was no longer invoked.
H. Assessment of Safety Consequences:
The safety significance of this activity was minimal. As discussed in EGM 11-003, Revision 2, enforcement discretion related to Secondary Containment operability during Mode 5 OPDRV activities is appropriate because the interim actions necessary to receive the discretion ensure an adequate level of safety.
Duane Arnold Energy Center 05000-331
Cause of Event:
The use of EGM 11-003, Revision 2 interim actions during the plant outage while in Mode 5 was a planned activity. As such, no cause determination was necessary.
IV. Corrective Actions:
Consistent with the guidance in the EGM, Duane Arnold Energy Center will submit a license amendment request (LAR) within twelve months after issuance of a notice of availability regarding a generic resolution of the issues surrounding the need for the EGM. This action is being tracked in the corrective action program.
V. Additional Information:
Previous Similar Occurrences:
A review of DAEC Licensee Event Reports found no other instances of DAEC invoking EGM 11-003, which was first issued in 2011.
EIIS System and Component Codes:
n/a Reporting Requirements:
This activity is being reported per 10 CFR 50.73(a)(2)(i)(B) as a Condition Prohibited By Technical Specifications.