05000382/LER-2001-005
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition |
| 3822001005R00 - NRC Website | |
REPORTABLE OCCURRENCE
On May 1, 2001, it was determined that potential exists for a fire in Fire Area RAB 27 to render both trains of Emergency Diesel Generator (EDG) Fuel Oil Transfer Pumps inoperable.
Assuming a concurrent loss of off-site power, the diesels would be operable for approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />, until the fuel in the day tanks would be depleted. This would place the plant in an unanalyzed condition. Therefore, the condition was reported, within 8 hrs, on May 1, 2001 to the NRC Operations Center pursuant to 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition that significantly degrades plant safety. The condition is herein being reported, within 60 days, pursuant to 10 CFR 50.73(a)(2)(ii)(B).
INITIAL CONDITIONS
Just prior to the discovery, Waterford 3 was operating in Mode 1 at 100% reactor power. No major systems, structures or components were out of service specific to the reported condition.
EVENT DESCRIPTION
On May 1, 2001, during performance of a 10 CFR 50 Appendix R review project, it was discovered that certain electrical cables in Fire Area RAB 27 were not protected (fire wrapped) as required to provide adequate separation from the redundant train. The area is provided with fire detection and fire suppression. Separation by a three hour fire barrier or 20 feet of distance between redundant trains (with no intervening combustibles / fire hazards) is not provided. Therefore a one-hour fire wrap was required on the cables. The plant area affected is a +7 elevation Reactor Auxiliary Building (RAB) Mechanical-Electrical and HVAC equipment room. In this area, the 'EV train is the protected train of safe shutdown equipment. The discovered unprotected cables were 480-volt power cables 32505A and 32505B (conduit 32505A-SB) routing from switchgear SSD-ESWGR-3113 to EMCC-312B, that pass through Fire Area RAB 27. EDG Fuel Oil Transfer Pump 'B' (EGF-MPMP-0001B) [DC] could become inoperable, due to loss of power supply, caused by a fire in the fire area. The Train 'A' EDG Fuel Oil Transfer Pump (WEGF-MPMP-0001A) [DC] could also become inoperable since its cables are, by design configuration, not protected from fire in that fire area. Therefore the fuel supplies to both trains of EDG could be impacted and the EDGs could run for only a limited cifbppr - ‘Itiolastio.coin FACILITY NAME (1) DOCKET (2) � LER NUMBER (6) PAGE (3) 00 01 -- 005 -- 6NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (1-2001) period of time (less than 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />) due to loss capability to refill the Day Tanks.
CAUSAL FACTORS
The condition was caused by a design analysis deficiency during the preparation of the original safe shutdown analysis. The original safe shutdown analysis was focused on essential "equipment" and later evolved to include "cables" for essential equipment.
CORRECTIVE ACTIONS
Temporary compensatory actions (hourly fire watches) were initiated in accordance with Section 3.7.11 of the Technical Requirements Manual (TRM). Compensatory actions will remain in place until permanent corrective actions are implemented.
Permanent corrective actions are being addressed under the plant corrective action program.
An Appendix R review project is in progress to fully evaluate the adequacy of the Waterford 3 fire protection design.
SAFETY SIGNIFICANCE
Fire Area RAB 27 has a low combustible loading and minimal other fire hazards. The potential for a fire in that area to impact both safe shutdown trains is low. The redundant conduits are located greater than 20 feet from each other with a non-fire rated wall and insignificant, intervening combustibles between the conduits. Although the wall contains deficiencies per fire barrier criteria (opening around duct penetrations), the wall would have significantly reduced or delayed the transmission of fire, heat, and products of combustion to the non-fire side of the wall.
In addition, both sides of the wall are provided with fire detection, which would have alarmed initiating immediate fire brigade response. Both sides of the wall are also provided with automatic sprinkler protection. Automatic sprinkler protection historically extinguishes most industrial fires.
This indicates that automatic fire extinguishing during the early stages of fire growth and development is a valid expectation. Thus it is believed that the fire would have been detected and extinguished prior to damage occurring to both shutdown trains. Therefore, it is believed that realistically, the plant Operators would have been able to achieve safe shutdown, The condition CfibPDF - wym.fastio.corn Waterford Steam Electric Station, Unit 3 � 05000482 1 FACILITY NAME (1) � DOCKET (2) � LER NUMBER (6) 01 — 005 — 00 6NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (1-2col) is being reported because Appendix R criteria forces the worst-case fire scenario, assuming the probability of a fire as being one and the concurrent probability of a loss of offsite power as being one. In the worst case scenario, the assumption is made that everything that is not protected from fire in the room is lost to the fire (regardless of actual fire loading in the area).
This event is not considered a Safety System Functional Failure (SSFF).
SIMILAR EVENTS
Two other similar events were identified that were reported by Waterford 3 over the last three and a half year period (1998 through current date) which involved discovery of Appendix R separation violations with potential for loss of both trains of Safe Shutdown Equipment due to inadequate design configuration analysis. The similar events were:
An Appendix R non-compliance condition involving inadequate separation of safe shutdown cables.
Cause: Design configuration and analysis: Design analysis deficiency.
Potential for loss of safe shutdown equipment by a fire in either of two separate fire areas.
Cause: Original design inadequacies in safe shutdown analysis. In one case an inadequate design change was involved.
ADDITIONAL INFORMATION
Energy Industry Identification System (EllS) codes are identified in the text within brackets H.
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