05000425/LER-2010-001, Regarding Closure of RHR Injection Valve in Mode 1
| ML101090066 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 04/16/2010 |
| From: | Tynan T Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-10-0714 LER 10-001-00 | |
| Download: ML101090066 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 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) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2) 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)(i)(B), Prohibited by Technical Specifications |
| 4252010001R00 - NRC Website | |
text
Tom Tynan Vice Preside;1) Vogtlc Southern Nuclear Operating Company. Inc.
7821 River Road WaynEsborc, 13eorgra 30830 Tel 706.825.31 ~1 Fax 7068263321 April 16, 2010 SOUIHERNA COMPANY Docket Nos.: 50-425 f\\lL-10-0714 U. S. Nuclear Regulatory Commission AnN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant-Unit 2 Licensee Event Report 2-2010-001 Closure of RHR Injection Valve in Mode 1 Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(v)(D) and 10 CFR 50.73(a)(2)(vii)(D) Southern Nuclear Operating Company (SNC) is submitting the enclosed Licensee Event Report.
This letter contains no NRC commitments. If you have any questions, please advise.
Respectfully submitted, 1.).1'/~
T. E. Tynan Vice President - Vogtle TET/TMH/sdc Enclosure: Unit 2 Licensee Event Report 2-2010-001 cc:
Southern Nuclear Operating Company Mr. J. 1. Gasser, Executive Vice President Mr. 1. E. Tynan, Vice President - Vogtle Ms. P. M. Marino, Vice President - Engineering
- U. S. Nuclear Regulatory Commission Log:
IPage 2 RType: CVC7000 U. S. Nuclear Regulatory Commission Mr. L. A. Reyes. Regional Administrator Mr. R. E. Martin, NRR Project Manager - Vogtle Mr. M. Cain, Senior Resident Inspector - Vogtle Mr. P. Boyle, NRC Project Manager
Enclosure Vogtle Electric Generating Plant-Unit 2 Licensee Event Report 2*2010-001 Closure of RHR Injection Valve in Mode 1
APPROVED BY OMB: NO. 3150.()104 EXPIRES: 0813112010 NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (9-2007)
Es~mated the NRC may not conduct or sponsor, and a person is not required to respond to, the
'inf";~ot;~n ~nll"";nn
\\3. PAGE Vogtle Electric Generating Plant - Unit 2 05000425 1 OF 4
- 4. TITLE Closure of RHR Injection Valve in Mode 1
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE B. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER SEQUENTIAL \\ REV MONTH DAY YEAR YEAR MONTH DAY YEAR NUMBER NO.
05000 FACILITY NAME DOCKET NUMBER 02 18 2010 2010 001 00 04 16 2010 05000 1
g. OPERATING MODE 1t. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (ensek all that apply) o 20.2201 (b) o 20.2203(a)(3)(i) o 50.73(a)(2)(i)(C)
~ 50.73(a)(2)(vii) 1 o 20.2201 (d) o 20.2203(a)(3)(ii) o 50.73(a)(2)(ii)(A) o 50.73(a)(2)(viii)(A) o 20.2203(a)(l) o 20.2203(a)(4) o 50.73(a)(2)(ii)(B) o 50.73(a)(2)(viii)(B) o 20.2203(a)(2)(i) o 50.36(c)(1 )(i)(A) o 50.73(a)(2)(iii) o 50.73(a)(2)(ix)(A}
- 10. POWER LEVEL o 20.2203(a)(2)(ii) o 50.36(c)(1 )(ii)(A) o 50.73(a)(2)(iv)(A) o 50.73(a)(2)(lC) o 20.2203(a)(2)(iii) o 50.36(c)(2) o 50.73(a)(2)(v)(A) o 73.71 (a)(4) o 20.2203(a)(2)(iv) o 50.46(a)(3)(ii) o 50.73(a)(2)(v)(B) o 73.71(a)(5) 100 o 20.2203(a)(2)(v) o 50.73(a)(2)(i)(A) o 50.73(a)(2)(v)(C) o OTHER o 20.2203(a)(2)(vi) o 50.73(a)(2)(i)(B) 181 50.73(a)(2)(v)(D)
Specify in Abstra~~elow or inj,iRC Form 3 A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME I~ELEPHONE NUMBER (Include Area Codel lVogtle Electric Generating Plant/Mark Hickox, Principal Licensing Engineer (706) 826-4129 MANU-REPORTABLE MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION o YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 181 NO DATE ABSTRACT (Limit fo 1400 spaces, i.e.* approximatf1ly 15 single-spaced typewritten lines)
On February 18,2010 while reviewing a partially completed surveillance procedure for verifying the operability of the Train B shutdown panel transfer function, it was discovered that the motor operated valve (MOV) that isolates Residual Heat Removal (RHR) flow to loops 3 and 4 cold legs had been momentarily stroked closed twice with the unit in Mode 1, on January 5, 2010. Stroking this valve closed in Mode I renders both trains of RHR inoperable since the required emergency core cooling flow from the RHR pump(s) cannot be assured, and requires entry into Technical Specification LCO 3.0.3.
The cause of this event was due to cognitive error by Operations department personnel applying fundamental knowledge of the Emergency Core Cooling System configuration needed to satisfy Technical Specification Limiting Condition of Operations (LeO) requirements. Also, the procedure used to perform the test was inadequate since at the time the valve was stroked, it did not contain a caution to alert the operator that the valve could not be stroked with the unit at power.
NRC FORM 366 (9-2007)
PRINTED ON RECYCLED PAPER
4 (If more space is required. use a.dditional copies of NRC Form 368A)
A.
REQUIREMENT FOR REPORT The VEGP Emergency Core Cooling System (ECCS) consists of three subsystems: centrifugal charging (high head), safety injection (intermediate head), and residual heat removal (low head).
Each of the three subsystems consist of two 100 percent capacity trains that are interconnected and redundant such that either train is capable of supplying 100 percent of the required flow to mitigate the accident consequences. Technical Specification 3.5.2 requires two trains of ECCS to be Operable in Modes 1-3. The design of the residual heat removal (RHR) subsystem at VEGP is such that each RHR pump must be capable of injecting into all four cold legs. There are two MOVs installed on the discharge of the RHR pumps that can isolate flow to the cold legs. One MOV isolates RHR injection flow to loops 1 and 2 cold legs while the other MOV isolates RHR injection flow to loops 3 and 4 cold legs. During the time the RHR to cold legs 3 and 4 MOV was closed, the low head accident required ECeS flow to the four cold legs from either RHR pump could not be assured. Therefore this condition is reportable under the following sections of IOCFR50.73:
IOCFR50.73(a)(2)(v)(D), "Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident."
10CFR50.73(a)(2)(vii)(D), "Any event where a single cause or condition caused. " two independent trains...to become inoperable in a single system designed to mitigate the consequences of an accident."
B.
UNIT STATUS AT TIME OF EVENT At the time of the event on January 5, 2010 Unit 2 was operating in Mode 1 at 100 percent rated thermal power. There was no other inoperable equipment that contributed to this event.
C.
DESCRIPTION OF EVENT
Technical Specification surveillance requirement (SR) 3.3.4.2 verifies each required remote shutdown panel control circuit and transfer switch performs the intended function every 18 months. At VEGP, there are two procedures that implement this surveillance requirement. One procedure contains all of the required components on the A train shutdown panel and another procedure contains all of the required components on the B train shutdown panel. Many of the components on the shutdown panel are capable of being operated with the unit at power (e.g.
during system outages) while others require the unit to be shutdown.
(If more space is required, USB additional copies of (If more space is required. use additional copies of NRC Form 366A)
E. ANALYSIS OF EYENT This event represents a loss of safety system function since during the brief period of time the valve was closed, emergency core cooling accident required flowrate from the low head RHR pumps could not be assured. However, based on a risk assessment of the valve being closed for the short duration involved, the increase in both core damage frequency (CDF) and large early release frequency (LERF) were found to be negligible. Additionally, there were no events which required an EeCS actuation during the time the valve was closed. Based on these considerations, there was no adverse affect on plant safety or on the health and safety of the public.
F. CORRECTIVE ACTIONS 1. A new procedure was developed for performing the remote shutdown surveillance test for the RHR cold leg injection MOYs. This procedure contains the necessary cautions to alert the user that the procedure cannot be performed in Modes 1,2 and 3.
2. The individuals involved with this event were coached to ensure an understanding of the relationships between surveillance procedures, Technical Specification LeOs, and use and applicability of Technical Specification Bases.
G. ADDITIONAL INFORMATION 1. Failed Components:
None 2. Previous Similar Event:
Licensee Event Report 1-1996-002 involved a similar event on Unit 1 in which this valve was stroked with the unit at power. The corrective actions from that event included counseling the operations department personnel, conducting a shift briefing and covering this event as part of the "Lessons Learned" segment during licensed operator re-qualification training.
These corrective actions to prevent recurrence proved not to be effective in preventing this event since they were one time actions that did not address the fundamental operator knowledge gap on the configuration requirements for the emergency core cooling system to ensure compliance with the Technical Specifications and accident analysis assumptions and further did not institutionalize the knowledge into plant procedures.
3. Energy Industry Identification System Codes:
Residual Heat Removal Low Pressure Injection System-BP PRINTED ON RECYCLED PAPER)