05000346/LER-2011-001, For Davis-Besse Nuclear Power Station, Regarding Pressurizer Code Safety Valve Setpoint Test Failures
| ML110760011 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  (NPF-003) |
| Issue date: | 03/11/2011 |
| From: | Allen B FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-11-062 LER 11-001-00 | |
| Download: ML110760011 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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 |
| 3462011001R00 - NRC Website | |
text
FENOC"E%%
5501 North State Route 2 FirstEnergy Nuclear Operating Company Oak Harbor, Ohio 43449 Barry S. Allen 419-321-7676 Vice President - Nuclear Fax: 419-321-7582 March 11, 2011 10 CFR 50.73 L-1 1-062 ATTN: Document Control Desk United States Nuclear Regulatory Commission Washington, D.C. 20555-0001
Subject:
Davis-Besse Nuclear Power Station, Unit 1 Docket Number 50-346, License Number NPF-3 Licensee Event Report 2011-001 Enclosed is Licensee Event Report (LER) 2011-001, "Pressurizer Code Safety Valve Setpoint Test Failures." This LER is being submitted to provide written notification in accordance with 10 CFR 50.73(a)(2)(i)(B) as operation in a condition prohibited by the Technical Specifications.
There are no regulatory commitments contained in this letter or its enclosure. The actions described represent intended or planned actions, are captured in the DBNPS Corrective Action Program, and are described for information only. If there are any questions or if additional information is required, please contact Mr. Patrick J.
McCloskey, Manager - Site Regulatory Compliance, at (419) 321-7274.
Sincerely, 4f 8.5. A HeX Barry S. All(&
Enclosure: LER 2011-001-00 cc: NRC Region III Administrator NRC Resident Inspector NRR Project Manager Utility Radiological Safety Board
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 10/31/2013 (10-2010)
, the NRC may (See reverse for required number of not conduct or sponsor, and a person is not required to respond to, the digits/characters for each block) information collection.
- 3. PAGE Davis-Besse Nuclear Power Station 05000346 1 OF 4
- 4. TITLE Pressurizer Code Safety Valve Setpoint Test Failures
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL IEREV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 08 06 2010 2011 001 00 03 15 2011 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
[E 20.2203(a)(3)(i)
El]
50.73(a)(2)(i)(C)
E]
50.73(a)(2)(vii) 1 El 20.2201(d)
E]
20.2203(a)(3)(ii)
E]
50.73(a)(2)(ii)(A)
E] 50.73(a)(2)(viii)(A)
E]
20.2203(a)(1)
E]
20.2203(a)(4)
E]
50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
E]
20.2203(a)(2)(i)
El]
50.36(c)(1)(i)(A)
E] 50.73(a)(2)(iii)
El] 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El]
20.2203(a)(2)(ii)
E]
50.36(c)(1)(ii)(A)
[] 50.73(a)(2)(iv)(A)
[] 50.73(a)(2)(x)
[] 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71 (a)(4) 100 E]
20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5)
E]
20.2203(a)(2)(v)
E]
50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER Specify in Abstract below
_ 20.2203(a)(2)(vi)
Z 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D) or in CAUSE OF EVENT (continued):
A contributing cause of the as-found test setpoint of the PSVs found to be greater than the TS allowable value of less than or equal to 2525 psig is the Pressurizer Code Safety Valve as-left allowable range (+/- 1 percent) does not provide a balanced margin to accommodate setpoint drift given the skewed +1 percentl-3 percent as-found acceptance requirements.
ANALYSIS OF EVENT
While both valves had as-found setpoints that exceeded the TS allowed value, the highest out of tolerance setpoint was only 10 psig higher than the required value. The transients described by Updated Safety Analysis Report (USAR) that can produce an RCS overpressurization were reviewed with respect to the out-of-tolerance valve setpoints. The review indicated that all applicable transients were analyzed: (1) without modeling the valves, (2) with a bounding setpoint tolerance or, (3) would have resulted in an acceptable peak pressure when the out-of-tolerance setpoints are considered. Therefore this issue had very low safety significance and did not prevent the PSVs from fulfilling their safety function.
Reportability Discussion:
NUREG-1022, Event Reporting Guidelines, states that discrepancies found in TS surveillance tests are normally assumed to occur at the time of the test unless there is firm evidence, based on a review of relative information, to indicate the discrepancy occurred earlier. The NUREG provides an example that multiple safety valve testing failures is an indication that the discrepancies may well have arisen over a period of time and did not occur just at the time of discovery. Evaluation of the PSV test history and potential failure modes for the PSV did not identify any information that would allow a conclusion that the valves were operable while the plant was operating in Mode 1, 2 or 3 as required by TS LCO 3.4.10. Therefore, this condition (two pressurizer safety valves exceeding the TS allowed setpoint) is reportable as a Licensee Event Report (LER) per 10 CFR 50.73(a)(2)(i)(B) as an operation or condition prohibited by the plant's TS based on the above guidance from NUREG-1022.
CORRECTIVE ACTIONS
During the Sixteenth Refueling Outage concluding June 2010, two PSVs were installed in place of the removed valves. These valves were also manufactured by Crosby Valve & Gage Company, Model Number HB-86-BP Type E series valves. These valves had As-Left set pressures of 2504 psig (RC1 3A) and 2496 psig (RC1 3B).
Procedures that govern the testing of the PSVs will be revised to establish a desired As-Left setpoint range of +0 percent to -1 percent (2500 psig to 2475 psig) of set pressure (2500 psig) with the As-Left setpoint adjusted to as close to 2475 psig as practicable. The two PSVs tested in August 2010 will be sent to a vendor facility to have the As-Left setpoint adjusted to as close to 2475 psig as practicable.
PREVIOUS SIMILAR EVENTS
Two previous events were found to be associated with high PSV setpoints at the DBNPS.
In 1996, a voluntary LER was submitted to the NRC which documented an occurrence where one of two Pressurizer Code Safety Valves removed during the Tenth Refueling Outage in Spring of 1996 had an initial lift setpoint of 3.08 percent greater than the setpoint value of 2525.
The apparent cause of the valve test failure was determined to be setpoint drift. The two safety valves were refurbished and their setpoints adjusted to within the allowable limit.
In 1994, a voluntary LER was submitted to the NRC which documented an occurrence where one of two Pressurizer Code Safety Valves removed during the Ninth Refueling Outage had an initial lift setpoint 2.44 percent greater than the setpoint value of 2525 psig. The apparent cause of the valve test failure was determined to be setpoint drift. The two safety valves were refurbished and their setpoints adjusted to within the allowable limit.