05000272/LER-2014-001
| Salem Generating Station - Unit 1 | |
| Event date: | 01-07-2014 |
|---|---|
| Report date: | 03-10-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition |
| 2722014001R00 - NRC Website | |
the Desk Officer, Office of Information and Regulatory Affairs, NEOB-1 0202, (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, aid a person is not required to respond to, the information collection.
05000272 20F4
PLANT AND SYSTEM IDENTIFICATION
Westinghouse — Pressurized Water Reactor (PWR/4) Auxiliary Feedwater System {BA} Energy Industry Identification System {EIIS} codes and component function identifier codes appear as {SS/CCC}
IDENTIFICATION OF OCCURRENCE
Event Date: October 3, 2013 Discovery Date: January 7, 2014
CONDITIONS PRIOR TO OCCURRENCE
Salem Units 1 and 2 were in Operational Mode 1. No additional structures, systems or components were inoperable at the time of the discovery that contributed to the event.
DESCRIPTION OF OCCURRENCE
On October 3, 2013, Salem Plant Maintenance workers were working on a HELB damper in the Unit 2, 23 Turbine Driven Auxiliary Feedwater (TDAFW) pump {BA/P} enclosure when an NRC Resident Inspector observed that the enclosure HELB barrier door was being held open for an extended period of time by an assigned door attendant. The Resident Inspector questioned this practice and requested that Salem provide the basis for this compensatory measure.
The temporary blocking open of HELB doors had become a standard practice at Salem in accordance with the Operability Assessment and Equipment Control Program. The procedure guidance states:
'When barriers are impaired to support maintenance/testing activities, the barrier can still be considered capable of performing its HELB function as long as a member of the work crew is designated as a barrier attendant whose responsibility it will be to effect proper closure when required. The designated barrier attendant shall remain within direct sight of the barrier while it is blocked open or removed and shall restore the barrier if an abnormal event occurs or the area is to be left unattended.
A review of procedure revisions documents a change in 2005 implementing this guidance with little or insufficient reasoning or regulatory basis. Regulatory and engineering reviews could not provide sufficient bases to indicate that a designated door attendant would be a sufficient compensatory measure to ensure operability of the adjacent motor driven auxiliary feedwater (MDAFW) pumps while the TDAFW pump enclosure door was open with steam valved in to the room.
On January 7, 2014, PSEG determined that the control of the HELB door to the 23 TDAFW pump enclosure did not ensure the operability of the MDAFW pumps. An 8-hour report was made to the NRC pursuant to 10 CFR 50.72(b)(3)(ii)(B) as "the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety.
CAUSE OF OCCURRENCE
The cause of this event is attributed to an organizational failure to ensure that guidance provided in plant HELB program procedures contained sufficient justification for compensatory actions used for barrier impairments. The stations HELB program was determined to be inconsistent with regulatory guidance.
PREVIOUS SIMILAR OCCURRENCES
A review of LERs at Salem Station dating back to 2011 identified no other HELB barrier related inoperability conditions. A review of work performed since 2011 in the Unit 1 and Unit 2 TDAFW pump rooms identified other occurrences in which work may have been performed with the HELB barrier door held or blocked open while steam was valved in to the enclosure.
SAFETY CONSEQUENCES AND IMPLICATIONS
The Salem Unit 1 and 2 Auxiliary Feedwater (AFW) {BA} systems serve each unit as backup systems for supplying feedwater to the secondary sides of the steam generators at times when the units Main Feedwater System is not available. The AFW system is relied upon to prevent core damage and system overpressurization in the event of accidents such as a loss of normal feedwater or a secondary system pipe rupture, and to provide a means for plant cooldown. Each unit has two MDAFW pumps and one TDAFW pump. Each units TDAFW pump is located in an enclosure provided with a steel door to contain the energy released by a postulated HELB in the room. The MDAFW pumps are located adjacent to the enclosure such that if a secondary steam HELB event were to occur in the TDAFW pump room while its door was open or disabled, the steam plume from the room could render both MDAFW pumps inoperable.
A postulated steam break in the TDAFW enclosure while the door is open or otherwise disabled could thus render both the TDAFW pump and the two MDAFW pumps inoperable preventing mitigation of the consequences of a secondary steam break.
There was no impact on the health and safety of the public as a result of this event. The probability of a HELB event occurring during the short time period while the door was impaired was very low. Thus the safety significance of the event was low.
The main steam piping inside the TDAFW pump enclosure is inspected in accordance with the In-Service Inspection (ISI) Program to ensure piping integrity and substantially reduce the likelihood of a guillotine pipe break. Pipe shrouding and restraints are provided on main steam lines for the TDAFW pump to limit pipe whipping and reduce the effects of steam line break impact on adjacent components. This combination of inspections and pipe shrouding and restraints reduces the likelihood of a guillotine break and its effect in the room. It is thus likely that should a leak occur, a designated door watch attendant would be able to perform the actions required to close the barrier door at the first sign of pipe leakage ensuring the functioning of the MDAFW pumps.
In the case in which a break of sufficient size would cause the designated door attendant to be unable to close the door, plant operators may be required to respond to a loss of AFW. Emergency operating procedures (EOPs) would direct operators to either establish cooling with the Residual Heat Removal system if available, or perform once-through Reactor Coolant System (RCS) heat removal by depressurizing the RCS through the pressurizer Power Operated Relief Valves and injecting coolant via the High Pressure Safety Injection pumps. These EOP strategies would preclude core damage in this unlikely event.
A review of this event determined that a Safety System Functional Failure (SSFF) as defined in Nuclear Energy Institute (NEI) 99-02 did occur.
CORRECTIVE ACTIONS
1. A plant-wide communication was made describing the HELB event, its impact on operability of plant equipment and corrective actions in progress.
2. A revision to the Operability Assessment and Equipment Control Program procedure has been made to ensure it conforms to the guidance of NRC RIS 2001-09, Control of Hazard Barriers.
3. Permanent signs will be installed on all HELB barrier doors prohibiting them from being blocked open without authorization from Salem Operations.
COMMITMENTS
No commitments are made in this LER.