05000278/LER-2009-004, Regarding Inoperable Ventilation Fan Results in Condition Prohibited by Technical Specifications
| ML092440803 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 08/31/2009 |
| From: | Stathes G Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 09-004-00 | |
| Download: ML092440803 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2782009004R00 - NRC Website | |
text
Exeln Exelon Nuclear www.exeloncorp.com Nuclea Peach Bottom Atomic Power Station r
1848 Lay Road Delta, PA 17314-9032 10CFR 50.73 August 31, 2009 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station (PBAPS) Unit 3 Facility Operating License No. DPR-56 NRC Docket No. 50-278
Subject:
Licensee Event Report (LER) 3-09-04 This LER reports a condition prohibited by Technical Specifications involving the inoperability of a High Pressure Service Water Subsystem. In accordance with NEI 99-04, the regulatory commitment contained in this correspondence is to restore compliance with the regulations. The specific methods that are planned to restore and maintain compliance are discussed in the LER. If you have any questions or require additional information, please do not hesitate to contact us.
Sincerely, Garey L. Stathes Plant Manager Peach Bottom Atomic Power Station GLS/djf/I R 938565 Attachment cc:
S. J. Collins, US NRC, Administrator, Region I F. L. Bower, US NRC, Senior Resident Inspector R. R. Janati, Commonwealth of Pennsylvania S. Grey, State of Maryland P. Steinhauer, PSE&G, Financial Controls and Co-owner Affairs INPO Records Center CCN: 09-61
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010 (9-2007)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.
- 13. PAGE Peach Bottom Atomic Power Station, Unit 3 05000278 1 OF 4
- 4. TITLE Inoperable Ventilation Fan Results in Condition Prohibited by Technical Specifications
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED M SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 04 20 2009 09 04 00 08 31 2009 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTnED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
[1 20.2201(b)
El 20.2203(a)(3)(i)
[I 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 1 El 20.2201(d)
El 20.2203(a)(3)(ii)
[I 50.73(a)(2)(ii)(A)
[] 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
[I 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
[I 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
[I 50.36(c)(1)(ii)(A)
[I 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
[I 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4) 100 %
C3 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71 (a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
Z 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in Description of the Event, continued prohibited by TS and is being submitted pursuant to 10CFR 50.73(a)(2)(i)(B).
Similarly, since TS 3.6.2.3, Residual Heat Removal (RHR) Suppression Pool Cooling and TS 3.6.2.4, RHR Suppression Pool Spray (EIIS: 80) require that a HPSW pump be capable of providing cooling to the RHR heat exchanger, Condition A of TS 3.6.2.3 and 3.6.2.4 (for one subsystem inoperable) were also affected by this condition.
Analysis of the Event
There were no actual safety consequences associated with this event. There were no plant design events during the period of exposure (4/13/09 to 7/5/09) that required operation of the Unit 3 HPSW system.
The Unit 3 HPSW/ESW Pump Room Ventilation system consists of two independent subsystems. Each subsystem has one supply fan and one exhaust fan and each subsystem is capable of performing the heat removal design requirement. The ventilation system is required to support the TS required HPSW and ESW systems by maintaining an acceptable operating environment for the four HPSW pumps and one ESW pump that are located in the Unit 3 portion of the safety related pump structure. This ventilation system removes heat generated by equipment operation during normal operation and following design basis events.
The TRM requires that one HPSW subsystem be declared inoperable if one HPSW/ESW ventilation subsystem is inoperable. If both HPSW/ESW ventilation subsystems are inoperable, then the TRM requires the declaration of both HPSW subsystems and one ESW subsystem to be inoperable.
The objective of the HPSW system is to provide a reliable supply of cooling water for RHR under post-accident conditions.
This includes supporting the Suppression Pool Cooling, Suppression Pool Spray, Drywell Spray and Shutdown Cooling modes of RHR for various design basis events.
Had a design basis event occurred during the time period of exposure (4/13/09 to 7/5/09), the redundant train of HPSW/ESW Pump Room Ventilation was operable and could have provided adequate cooling in the HPSW/ESW Pump Room to allow for proper operation of the HPSW Pumps and ESW Pump. Therefore, there was no actual loss of safety function involved with this event. This event is not considered risk significant.
Additionally, although the 3B HPSW/ESW Pump Room ventilation subsystem was considered inoperable since 4/13/09, it is reasonable to assume that the 3B HPSW/ESW Pump Room ventilation subsystem operated without incident on occasions when a Unit 3 HPSW pump was operated. The longest run of a Unit 3 HPSW subsystem occurred for approximately 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> in June 2009.
Therefore, during the period of exposure, the 38 HPSW/ESW Pump Room ventilation subsystem is judged to have had some capability to perform its design function.
Analysis of the Event, continued However, it could not be assured that if a design basis event occurred during the period of exposure (i.e., 4/13/09 to 7/5/09) that the 3B HPSW/ESW Pump Room Ventilation Supply Fan could have operated for a time period long enough to support the longer term cooling requirements of the HPSW system.
Cause of the Event
The 38 HPSW/ESW Pump Room Ventilation Supply Fan tripped due to inadequate torque applied to the connection of the motor starter contactor and the thermal overload assembly by site maintenance personnel (utility, non-licensed).
As-found inspections identified that there existed discoloration (i.e., heating) of the 'B' phase solid link connection point.
This inadequately torqued connection caused a high resistance connection that led to actuation of the thermal overload relay. The underlying cause of this condition was that the associated maintenance procedure did not provide clear direction for torquing the connection. Specifically, the associated procedure step directed two actions in one step and did not require a peer check of the torque that was applied to the connection.
The Eaton Corporation supplied the motor starter mechanism (A200, NEMA Size 2).
Corrective Actions
The motor starter mechanism / thermal overload relay was repaired including the appropriate torquing of the connections between the motor starter mechanism and the thermal overload relay.
Appropriate breaker testing was performed and the equipment was restored to an operable status on 7/5/09.
Other motor starter mechanism / thermal overload relays that were worked on during the same time period as the 38 HPSW/ESW Pump Room Ventilation Supply Fan were checked for proper torque and no similar concerns were identiifed. Additional exent of condition reviews are planned.
The applicable maintenance procedure is being upgraded to ensure clear control and verification of the torquing of the motor starter mechanism / thermal overload relay connections.
Lessons learned from this event were shared with the maintenance staff.
Previous Similar Occurrences There were no previous LERs identified involving inadequate torquing.PRINTED ON RECYCLED PAPER NRIC FORM 366A (9-2007)
PRINTED ON RECYCLED PAPER