05000387/LER-2006-003, Regarding Motor Operated Valve Stem Nut Failures
| ML062190207 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 07/26/2006 |
| From: | Saccone R Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NUREG-1022, Rev 2, PLA-6094 LER 06-003-00 | |
| Download: ML062190207 (7) | |
| 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 |
| 3872006003R00 - NRC Website | |
text
R. A. Saccone Vice President - Nuclear Operations PPL Susquehanna, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3959 Fax 570.542-1504 rasaccone@pplweb.com Ii P
% T JUL 2 6 2006 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop OP1-17 Washington, DC 20555 SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-387/2006-003-00 PLA-6094 Docket 50-387 Attached is Licensee Event Report 50-387/2006-003-00. The events described in this report do not specifically meet the criteria established for required reporting. However, motor operated valve (MOV) stem nut degradation experienced on two valves at the Susquehanna Steam Electric Station is likely to be of general interest to the industry.
Accordingly, this report is submitted under the Voluntary Reporting guidance described in Section 2.7 of NUREG-1022, Rev. 2.
There were no actual consequences to the health and safety of the public as a result of this event.
No new regulatory commitments have been created through issuance of this report.
Vice President - Nuclear Operations Attachment ov--
Document Control Desk PLA-6094 cc:
Mr. S. J. Collins Regional Administrator U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19408 Mr. A. J. Blarney 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
INFC FORM 36 U.S. NUCLEAR REGULATORY APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007 (6-2004)
, the NRC may not conduct of digits/characters for each block) or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME Susquehanna Steam Electric Station - Unit 1
- 2. DOCKET NUMBER
- 3. PAGE 05000387 1 OF5
- 4. TITLE Motor Operated Valve Stem Nut Failures
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILIES INVOLVED SEQUENTIAL REV FACILITY NAME
)OCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR 5000 FACILITY NAME OCKET NUMBER 04 06 2006 2006 003 00 07 26 2006 5000
- 9. OPERATING MODE 11.THIS REPORT IS SUBMITTED PURSUANTTO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 4 [E 20.2201(b)
[I 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
[: 50.73(a)(2)(vii)
- 10. POWER LEVEL 0l 20.2201(d)
[I 20.2203(a)(3)(ii)
[I 50.73(a)(2)(ii)(A)
[I 50.73(a)(2)(viii)(A)
O[ 20.2203(a)(1)
[I 20.2203(a)(4)
[I 50.73(a)(2)(ii)(B)
[E 50.73(a)(2)(viii)(B) 0%
[I 20.2203(a)(2)(i)
[l 50.36(c)(1)(i)(A)
[] 50.73(a)(2)(iii)
[j 50.73(a)(2)(ix)(A) ol 20.2203(a)(2)(ii)
[I 50.36(c)(1)(ii)(A)
[] 50.73(a)(2)(iv)(A)
[I 50.73(a)(2)(x)
[I 20.2203(a)(2)(iii)
[I 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71 (a)(4)
[I 20.2203(a)(2)(iv)
[I 50.46(a)(3)(ii)
[I 50.73(a)(2)(v)(B)
[E 73.71 (a)(5)
El 20.2203(a)(2)(v)
[I 50.73(a)(2)(i)(A)
[I 50.73(a)(2)(v)(C) 0 OTHER Voluntary Report El 20.2203(a)(2)(vi)
[E 50.73(a)(2)(i)(B)
[l 50.73(a)(2)(v)(D)
Specify in Abstract below or in (If more space is required, se ad tional copies of NRC Form 366A)
Operating Experience Review Susquehanna's review did not identify any generic studies or roll up reports highlighting stem nut thread wear as a significant issue. To the contrary, many such reports do not cite stem nut wear at all. There have been, however, a number of reported stem nut failures within the industry. These events suggest that visual inspection of valve stems for signs of stem nut wear is not, by itself, an effective means for monitoring long term wear of stem nuts. The events also indicate that proceduralized stem nut inspection criteria and the use of diagnostic data are useful tools for identifying degraded stem nut threads.
Physical Characteristics Affecting Stem Nut Thread Wear Certain physical characteristics can affect the amount and rate of stem nut thread wear. These characteristics include stem nut material, applied loads, and usage (number of stem nut rotations). Additionally, fit and lubrication can also impact stem nut thread wear. Upon reviewing these potential wear factors, it was determined that most did not present unexpected or undue effect on valves HV1 51 F004C and HV1 51 F004D. This review did, however, indicate that improvements in Susquehanna's methods for lubricating valve stems are needed. The PM activity to lubricate valve stems does not require a valve stroke. There is, therefore, no assurance that the lubrication reaches the stem nut threads until the valve is next stroked.
CORRECTIVE ACTIONS
The following corrective actions have been completed:
A wide-spread inspection of MOVs with indications of stem nut thread wear was undertaken to assess the condition of MOV stem nuts and to replace those stem nuts with wom threads.
The following corrective actions are planned:
Inspections and stem nut replacements of additional MOVs will be performed.
" The current two year PM activity bases will be revised to clarify the intent and limitations of stem nut inspections.
(Visual inspections are not effective in detecting long term stem nut wear).
A new PM activity will be created that periodically inspects stem nuts on selected valves.
A method and acceptance criteria for measurement of stem nut wear will be established.
Detailed instructions for performance of stem nut inspections will be incorporated into existing procedures.
Direction for monitoring and trending of stem nut thread wear using MOV diagnostic data will be proceduralized.
Stem lubrication PM activities will be modified to include valve stroking.
ADDITIONAL INFORMATION
Failed Components: Suppression Pool Suction Valves for RHR pumps 'C' and 'D', HV1 51 F004C and HV1 51 F004D Manufacturer.
Anchor Darling Valve Company Model:
W8522332B