05000277/LER-2010-002, Regarding Improperly Fastened Rod Hanger Results in Inoperable Subsystem of Emergency Service Water
| ML103200271 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  (DPR-044, DPR-056) |
| Issue date: | 11/15/2010 |
| From: | Stathes G Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 10-002-00 | |
| Download: ML103200271 (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 |
| 2772010002R00 - NRC Website | |
text
Exekans.
Exelon Nuclear www.exeloncorp.com Nuclear Peach Bottom Atomic Power Station 1848 Lay Rd.
Delta, PA 17314 10CFR 50.73 November 15, 2010 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station (PBAPS) Units 2 and 3 Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278
Subject:
Licensee Event Report 2-10-02 Enclosed is a Licensee Event Report concerning a condition prohibited by Technical Specifications involving a deficiency in a rod hanger associated with the 'A' Emergency Service Water system discharge pipe.
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/IR 1118711 / 1114812 Attachment cc:
US NRC, Administrator, Region I 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: 10-93
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013
- 10-2010)
, the NRC may e for each b rock) not conduct or sponsor, and a person is not required to respond to, the digits/characters finformation collection.
- 3. PAGE Peach Bottom Atomic Power Station (PBAPS) 05000277 1 OF 4
- 4. TITLE Improperly Fastened Rod Hanger Results in Inoperable Subsystem of Emergency Service Water
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED I
FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEUENTIAL REV MONTH DAY YEAR PBAPS Unit 3 05000278 M N H D Y Y A YE R NUMBER NO.
FACILITY NAME DOCKET NUMBER 09 18 2010 10 002 -
0 11 15 2010 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
El 20.2203(a)(3)(i)
[I 50.73(a)(2)(i)(C)
C1 50.73(a)(2)(vii) 5 E0 20.2201(d)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
[E 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
_ 20.2203(a)(2)(i)
[E 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
[I 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL [I 20.2203(a)(2)(ii)
[I 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
[I 20.2203(a)(2)(iii)
El 50.36(c)(2)
[I 50.73(a)(2)(v)(A)
El 73.71 (a)(4) 0%
[1 20.2203(a)(2)(iv)
[1 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)
[I 50.73(a)(2)(v)(C) 0l OTHER El 20.2203(a)(2)(vi)
[
50.73(a)(2)(i)(B)
[I 50.73(a)(2)(v)(D)
Specify in Abstract below or in
Analysis of the Event
The ESW system (EIIS: CC) is a standby system which is shared between Units 2 and 3. It is designed to provide cooling water for the removal of heat from equipment, such as Emergency Diesel Generators (EDGs) and room coolers for Emergency Core Cooling System equipment, required for a safe reactor shutdown following a Design Basis Accident or transient. Upon receipt of a loss of offsite power signal, or whenever any EDG is in operation, the ESW system will provide cooling water to its required loads.
The ESW system consists of two redundant subsystems.
The affected rod hanger (33HB-S143) supports the discharge pipe (EIIS: P) of the 'A' ESW pump downstream of the discharge check valve. The rod hanger consists of a threaded rod fastened at its top to a nearby structural steel member and at the bottom to the circular pipe clamp. Rod hanger 33HB-S143, as well as adjacent restraints, carry piping system deadweight to limit pipe stress to within code allowables including nozzle and anchor loads at the 'A' ESW pump.
There were no actual safety consequences associated with this event. The degraded condition of rod hanger 33HB-S143 (EIIS: H) would have only affected the 'A' ESW subsystem during postulated seismic conditions. This condition was determined to not affect the 'B' ESW subsystem. There have been no actual adverse affects as a result of seismic events at PBAPS. If a design basis seismic event had occurred, the rod hanger deficiency could have resulted in overstressing of the 'A' ESW pump (EIIS: P) anchor bolts. Therefore, if a design basis seismic event were to occur, continued operability of the 'A' ESW subsystem could not be assured during the design basis seismic event. For other design events (non-seismic related), the adverse condition of the rod hanger would not have significantly affected the ability of the 'A' ESW subsystem to perform its safety function.
Cause of the Event
The original (construction) installation of the rod hanger was deemed to be inadequate since jam nuts were not installed to prevent the loosening of the top fastener which connects the rod hanger to a nearby structural steel member.
It is believed that over time the top fastener on the rod hanger loosened since no jam nut was installed. This resulted in the rod hanger no longer carrying the required pipe load.
The underlying cause was determined to be due to an inadequate design drawing.
The original construction design drawing did not properly specify that the load bearing members under tension were to be staked, pinned or double-nutted.
Corrective Actions
The top attachment nut for rod hanger 33HB-$143 was tightened and staked on 9/28/10. The drawing associated with this hanger will be upgraded to clearly require staking / jam nut requirements.
A sample of similar hanger drawings were reviewed for staking requirements.
Systems reviewed included Residual Heat Removal, High Pressure Coolant Injection, Main Steam, ESW, and High Pressure Service Water. These drawings were found to require jam nuts, tack welds or staking of pipe clamps, lugs and load bearing threaded rod connections such as turnbuckles, weldless eye nuts, clevises, etc.
The hanger 33HB-$143 drawing was the only drawing identified that did not include specific requirements for staking the load bearing threaded rod connections.
Other actions are being pursued in accordance with the site Corrective Action Program.
Previous Similar Occurrences Previous concerns with the similar hanger on the 'B' ESW subsystem was identified in 2007 and 2009.
For these occurrences, it was determined that the hanger was carrying load and no stress analysis was required or performed. At those times, there were no additional walkdowns performed to identify similar existing conditions.