05000387/LER-2004-002, Regarding Loss of Safety Function Due to Both Loops of Emergency Service Water Being Inoperable
| ML041390507 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 05/04/2004 |
| From: | Richard Anderson Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-5751 LER 04-002-00 | |
| Download: ML041390507 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3872004002R00 - NRC Website | |
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Richard L Anderson Vice President - Nuclear Operations PPL Susquehanna, LLC 769 Salem Boulevad a* s A
Berwick, PA 1860k,
.3 Tel. 570.542.3883 Fax 570.542.1504 rlanderson@pph" n0 la, TM MAY 0 4 2004 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop O-P 1-17 Washington, DC 20555 SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-387/2004-002-00 LICENSE NO. NPF-14 PLA-5751 Docket No. 50-387 Attached is Licensee Event Report (LER) 50-387/2004-002-00. This event was determined to be reportable per 10 CFR 50.73(a)(2)(v)(D), for a condition that could have prevented the fulfillment of a safety function. In addition, this event is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B), for a condition prohibited by Technical Specifications.
On March 9, 2004, it was identified that on March 5, 2004, the Unit 1 'A' and 'B' loops of the Emergency Service Water (ESW) system were inoperable for approximately one hour.
On March 5, 2004, maintenance personnel erroneously removed a blank flange from the
'B' loop of ESW while the 'A' loop was already isolated to support the installation of a plant modification. Because this condition was not discovered until March 9, 2004, several actions were not taken as required by Technical Specifications.
This event resulted in no actual adverse consequences to the health and safety of the public.
No commitments are associated with this LER.
Richard L. Anderson Vice President - Nuclear Operations Attachment
.4fiA Document Control Desk PLA-5751 cc:
Mr. H. J. Miller Regional Administrator U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19408 Mr. S. L. Hansell Sr. Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 35 Berwick, PA 18603-0035 Mr. R. Osborne Allegheny Electric Cooperative P. 0. Box 1266 Harrisburg, PA 17108-1266 Mr. R. R. Janati Bureau of Radiation Protection Rachel Carson State Office Building P. 0. Box 8469 Harrisburg, PA 17105-8469
Abstract
On March 9, 2004, it was identified that both the Unit 1 'A' and 'B' loops of the Emergency Service Water (ESW) system were inoperable for a period of approximately one hour on March 5, 2004. On March 5, 2004, at 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />, maintenance personnel erroneously removed a blank flange in the Unit 1 'B' loop of ESW instead of the 'A' loop of ESW, which was already isolated to support the Ul1 3RO outage. This resulted in a loss of safety function for the ESW system. In addition, several other systems important to safety were affected. Because the condition was not discovered until March 9, 2004, several required Technical Specification (TS) actions were not taken. As such, this LER is being submitted in accordance with 10 CFR 50.73(a)(2)(v)(D) and (a)(2)(i)(B) for a loss of safety function and for a condition prohibited by TS, respectively.
The cause of this event was attributed to human performance. No pre-job brief or energy control process brief was conducted with the maintenance personnel (Crew B) assigned to assist the original maintenance personnel (Crew A) in removing the blank flange in the 'A' loop of the ESW system. In addition, a less than adequate turnover was provided by Crew A to Crew B. PPL performed a risk assessment which concluded that there was no risk impact to either Unit 1 or Unit 2 since the ESW system remained capable of supplying water to necessary heat loads on both units and common.
Expectations and coaching were provided to appropriate maintenance personnel. Lessons learned will be incorporated into PPL's Human Performance / Work Standards training for plant personnel. Improvement in this area has been recognized by PPL and is one of the station's key initiatives for 2004.
NRC FORM 366 (7-2001)
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Fonn 366A)
CAUSE OF EVENT
The cause of this event was attributed to human performance. No pre-job brief or energy control process (ECP) brief was conducted with the maintenance personnel (Crew B) assigned to assist the original maintenance personnel (Crew A) in removing the blank flange at valve 11 1130 in the 'A' loop of the ESW system. In addition, a less than adequate turnover was provided by Crew A to Crew B.
ANALYSIS / SAFETY SIGNIFICANCE Actual Consequences:
Unit 2 TS LCO 3.0.3 applied for the one-hour time period when the blank flange in the 'B' loop of the ESW system was un-bolted and the 'A' loop of ESW was isolated to support plant modifications. During this event, the 'B' loop ESW supply to the Unit 2 loads remained functional since there was at least one closable isolation valve (111103) and one anchor point (i.e., the ground) between the blank flange and the ESW piping to the Unit 2 loads. In addition, although the 'A' loop of ESW was inoperable, only the 'A' loop ESW supply to the Unit 1 loads was inoperable. The 'B' loop ESW supply to the Unit 2 loads remained functional. As such, the 'A' and 'B' loops of ESW to the Unit 2 loads remained fully functional at all times.
No unavailability or maintenance rule functional failures were involved.
During this event, the ESW supply to the diesel generators (DGs) also remained operable because there was at least one closable isolation valve (111103) in the 'B' loop of ESW between the DGs and the blank flange and one anchor point (i.e., the ground) between the blank flange and the ESW piping. There was no impact to the 'A' loop ESW supply to the DGs since the 'A' loop of ESW was isolated downstream of the DGs to support plant modifications.
PPL performed a risk assessment which concluded that there was no risk impact to either Unit 1 or Unit 2 since the ESW system remained capable of supplying water to necessary heat loads on both units and common.
Potential Consequences:
If the ESW system had been in operation while maintenance personnel were removing the incorrect flange in the 'B' loop, it is unlikely they would have been able to remove the blank flange due to system pressure (assuming leakage past closed valve HV-1 1143B had pressurized the section of pipe). Previous operating experience has shown that leakage from valve HV-1 11 43B has been negligible. In the event that the ESW system had started while maintenance was removing the incorrect flange, leakage from the open pipe would have been minimal since the section of pipe between the blank flange and closed valve HV-1 1 143B was not pressurized and any leakage out of the flange would be limited to leakage past valve HV-1 1 143B.
In accordance with TS, an LCO was entered for the 'B' loop of ESW since the system piping is not analyzed if a seismic event had occurred during the one-hour time period. The portion of the 4-inch pipe (where the blank flange was located) that was vulnerable to a seismic break was approximately 3 inches (if more space is required, use additional copies of NRC Form 366A)of ASME liI, safety-related, seismic Class 1 pipe. As previously stated, the blank flange was unbolted between closed valve HV-1 11 43B and check valve 111131. At the time of this event, valve HV-1 11 43B was maintaining the ESW pressure boundary. In addition, the physical arrangement of the ESW system piping in this area leaves valve HV-1 11 43B cantilevered about 12 inches from the 12-inch diameter HRC-1 01 pipe ('B' loop ESW supply). This, in conjunction with the guide at the floor penetration for the pipe and the anchor approximately 10 feet above the take off for HV-1 11 43B, precludes the failure of the 4-inch or the 12-inch ESW piping during a seismic event.
Based upon the above discussion, the actual and potential safety significance of this event was minimal.
There was no impact to the health and safety of the public.
CORRECTIVE ACTIONS
The corrective actions that have been completed are:
Expectations and coaching were provided to the appropriate maintenance personnel.
- The blank flange in the 'A' loop of ESW (at valve 111130) was removed in accordance with plant procedures. The blank flange at valve 111131 in the 'B' loop of ESW was determined not to require reinstallation, since there was no leakage past closed valve HV-1 1 143B.
The key corrective actions to be completed are:
Incorporate lessons learned into the PPL Human Performance / Work Standards training for plant personnel. The need for improvement in this area has been recognized by PPL and is one of the key initiatives for 2004.
Incorporate this event into continuing training for mechanical and electrical maintenance personnel.
PREVIOUS SIMILAR EVENTS
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