05000395/LER-2012-002, Seismically Qualified Refueling Water Storage Tank Aligned to Non-Seismic Piping
| ML12222A177 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 08/07/2012 |
| From: | Gatlin T South Carolina Electric & Gas Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 12-002-00 | |
| Download: ML12222A177 (4) | |
| 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 |
| 3952012002R00 - NRC Website | |
text
Thomas D. Gatlin Vice President, Nuclear Operations 803.345.4342 A SCANA COMPANY August 7, 2012 Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555
Dear Sir / Madam:
Subject:
VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 LICENSEE EVENT REPORT (LER 2012-002-00)
SEISMICALLY QUALIFIED RWST ALIGNED TO NON-SEISMIC PIPING Attached is Licensee Event Report (LER) No. 2012-002-00 for the Virgil C. Summer Nuclear Station Unit 1. This report describes the inoperability of the Refueling Water Storage Tank (RWST) resulting from its alignment to the non-seismically qualified non-safety related piping of the Spent Fuel Pool Purification Loop. This report is submitted in accordance with 10 CFR 50.73(a)(2)(i)(B).
This letter contains no regulatory commitments. Should call Bruce Thompson at (803) 931-5042.
you have any questions, please Very truly yours, Thomas D. Gatlin JMW/TDG/wm Attachment c:
K. B. Marsh S. A. Byrne J. B. Archie N. S. Cams J. H. Hamilton R. J. White W. M. Cherry V. M. McCree R. E. Martin NRC Resident Inspector M. N. Browne Paulette Ledbetter J. C. Mellette EPIX Coordinator K. M. Sutton INPO Records Center Marsh USA, Inc.
Maintenance Rule Engineer NSRC RTS (CR-12-02439)
File (818.07)
PRSF (RC-12-0100)
- - Ziig~Q-kA~-L Virgil C. Summer Station - Post Office Box 88. Jenkinsville, SC - 29065. F (803) 345-5209
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)
, the NRC may rfor each b
,ock) not conduct or sponsor, and a person is not required to respond to, the digits/characters finformation collection.
- 3. PAGE Virgil C. Summer Nuclear Station Unit 1 05000 395 1
OF
- 4. TITLE Seismically Qualified Refueling Water Storage Tank Aligned to Non-Seismic Piping
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR FACILITY NAME DOCKET NUMBER NUMBER NO.
05000 FACILITY NAME DOCKET NUMBER 06 14 2012 2012 2
0 08 07 2012 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 1
[] 20.2201(b)
[] 20.2203(a)(3)(i)
[] 50.73(a)(2)(i)(C)
E] 50.73(a)(2)(vii)
[] 20.2201(d)
[] 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
E] 20.2203(a)(1)
[] 20.2203(a)(4)
[] 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
[_] 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
[] 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL
[]
20.2203(a)(2)(ii)
[] 50.36(c)(1)(ii)(A)
[] 50.73(a)(2)(iv)(A) j]
50.73(a)(2)(x) 1] 20.2203(a)(2)(iii)
El 50.36(c)(2)
[] 50.73(a)(2)(v)(A)
[]
73.71(a)(4) 100%
[] 20.2203(a)(2)(iv)
E] 50.46(a)(3)(ii)
[] 50.73(a)(2)(v)(B)
E] 73.71(a)(5)
E] 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
[]
50.73(a)(2)(v)(C)
E] OTHER
[] 20.2203(a)(2)(vi)
[] 50.73(a)(2)(i)(B)
[] 50.73(a)(2)(v)(D)
Specify in Abstract below or in operation of the plant, which under the interpretation provided by NRC Information Notice (IN) 2012-01, is considered to be a condition prohibited by TS, and is reportable pursuant to 10 CFR 50.73(a)(2)(i)(B) requiring a 60 day Licensee Event Report (LER) notification to the NRC.
CAUSE OF EVENT
The cause of this event was that the Design Basis Documents (DBDs) describing the RWST and the SFP Purification Loop do not describe RWST cleanup/recirculation during operation. The Updated Final Safety Analysis Report (UFSAR) Section 9.1.3 states that the SFP Purification pump can take suction from and return to the RWST; however, no operational limitations are discussed. Based on this, personnel did not question the extended use of the SFP Purification Loop aligned to the RWST during normal operation. This condition was not reconciled during original procedure development. Subsequent technical and safety reviews also failed to identify that the conditions were outside the plant design basis.
Upon issuance of IN 2012-01, VCSNS discovered that this alignment was in fact outside its licensing and design bases, rendering the RWST inoperable during operation for a period longer than allowed by TS. The lack of stated operational limitations regarding RWST/SFP Purification alignment created a human-error-likely situation whereby the integrity of the RWST's seismic classification was compromised when it was aligned to the SFP Purification Loop.
During the apparent cause evaluation for this event, the extent of condition evaluation revealed that a similar condition exists in the procedure for increasing the level in the accumulators. The evolution involves aligning the RWST to the hydro test pump via a normally closed safety related valve XVT08932-SI (Hydro Pump Suction Valve). This valve isolates the RWST from a section of 2-inch non-safety non-seismic piping leading to a connection for the hydro test pump. A past operability evaluation is in process to determine if the RWST was unisolated from non-seismic piping for longer than permitted by TS 3.5.4 LCO.
ANALYSIS OF EVENT
The consequences of this event were minimal since a seismic event had not occurred while the SFP Purification System was servicing the RWST. An engineering past operability evaluation was performed and determined that the potential outflow from the RWST due to leakage from the SFP Purification Loop did not challenge the RWST design basis over the past three years. The overall impact to the Core Damage Frequency (CDF) from an operator failing to close the manual code boundary valve (XVT06701-SF) that isolates the RWST from the SFP Purification Loop is less than the significance threshold of 1.OE-06. The estimated overall impact to the CDF is approximately 3.43E-07; a small increase of less than 3%.
CORRECTIVE ACTIONS
Station Orders 11-06 and 11-22 were imposed to prevent alignment of the RWST to the non safety-related SFP Purification Loop. LAR 10-03912 was submitted to the NRC on 6/29/2012 to periodically open the seismically qualified manual ASME code boundary valve (XVT06701-SF) during Modes 1-4 under administrative controls. The LAR provides time (two fuel cycles following LAR approval) for VCSNS to complete a plant modification to address the issue.