05000425/LER-2014-001, Regarding Automatic Reactor Trip Due to Low Steam Generator Level
| ML14154A050 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 05/30/2014 |
| From: | Tynan T Southern Co, Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-14-0809 LER 14-001-00 | |
| Download: ML14154A050 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(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 |
| 4252014001R00 - NRC Website | |
text
Tom E. Tynao Vice President Vogtle -Units 1 & 2 Southern Nuclear Operating Company, Inc.
i821 RIVer Road Waynesboro. GA 30830 SOUTHERN A.
May 30, 2014 Docket No:
50-425 Tel 706 826 3151 Fax 205 980.3321 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 VogUe Electric Generating Plant - Unit 2 Licensee Event Report 2014-001-00 COMPANY NL-14-0809 Automatic Reactor Trip Due To Low Steam Generator Level ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A), Southern Nuclear Operating Company (SNC) is submitting the enclosed Licensee Event Report, 2-2014-001. This letter contains no NRC commitments. If you have any questions, please contact Kevin Walden at (706) 848-4290.
Respectfully submitted, Tom E. Tynan Site Vice President - Vogtle TET/KCW Enclosure: Unit 2 licensee Event Report 2014-001-00 cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. T. E. Tynan, Vice President-Vogtle 1 & 2 Mr. B. L. lvey, Vice President-Regulatory Affairs Mr. D. R. Madison, Vice President-Fleet Operations Mr. B. J. Adams, Vice President-Engineering Mr. S. C. Waldrup, Regulatory Affairs Manager-Vogtle Mrs. M. A. Cline, Operating Experience Coordinator-Vogtle RType: CVC7000 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Senior Project Manager -VogUe Mr. L. M. Cain, Senior Resident Inspector -Vogtle
Vogtle Electric Generating Plant-Unit 2 Licensee Event Report 2014-001-00 Automatic Reactor Trip do to Steam Generator Low Level Enclosure Unit2licensee Event Report 2014-001-00
NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 0113112017 (02-2014)
/y.Aro,f1 Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.
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Reported lessons learned are incorporated into the licensing process and fed back to industry.
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- J Send comments regarding burden estimate to the FOIA, Privacy and Information Collections LICENSEE EVENT REPORT (LER)
Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to lnfocollects.Resounoe@nrc.gov, and to the Desk Officer, Office of Information and (See Page 2 for required number of Regulatory Affairs, NEOB-10202, (315().()104), Office of Management and Budget Washington, DC digits/characters for each block) 20503. If a means used to impose an information collection does not display a currenOy valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Vogtle Electric Generating Plant-Unit 2 05000425 1 OF 3
- 4. TITLE Automatic Reactor Trip Due To Low Steam Generator Level
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR N/A FACILITY NAME DOCKET NUMBER 04 08 2014 2014 -
001
- - 00 05 30 2014 N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 2o.22o1(b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C) 0 50.73(a)(2)(vii) 1 D 2o.2201(d) 0 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A)
D 20.2203(a)(1)
D 20.2203(a)(4) 0 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B)
D 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL D 20.2203(a)(2)(ii) 0 50.36(c)(1 )(ii)(A)
[8l 50. 73(a)(2)(iv)(A) 0 50.73(a)(2)(x) 0 20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(A)
D 73.71(a)(4) 100 0 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B) 0 73.71(a)(5) 0 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C)
D OTHER 0 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D)
Specify in Abstract below or in A. REQUIREMENT FOR REPORT
- 6. LER NUMBER I SEQUENTIAL I NUMBER 001 REV NO.
00
- 3. PAGE 2
OF This report is required per 10CFR 50.73(a)(2)(iv)(A) due to an unplanned automatic actuation of the Reactor Protection System (RPS) and automatic actuation of the Auxiliary Feedwater System (AFW) and Feedwater Isolation (FWI) Engineered Safety Features Actuation Systems (ESFAS).
B. UNIT STATUS AT TIME OF EVENT Mode 1, 1 00 percent power
C. DESCRIPTION OF EVENT
While operating at 1 00 percent power, Unit 2 experienced a low-low level alarm in Steam Generator 3.
This resulted in an automatic RPS actuation due to low-low level in Steam Generator 3.
AFW actuated and Main Feedwater isolated following the RPS actuation, as expected. All rods inserted and the plant was stabilized in Mode 3. Decay Heat was discharged to the condenser and no complications were experienced during the trip as all systems responded as designed.
The source of the water intrusion into the primary MFRV positioner was the result of a small leak (3 drops per minute) approximately eighteen feet above the positioner conduit. The collection area of the water was not immediately identified and as a result of less than adequate installation of the flex conduit, water accumulated inside the positioner housing. Over time, the accumulation of water inside the positioner housing reached a level resulting in an electrical short circuit of the primary MFRV positioner. This resulted in erroneous feedback from the primary positioner to the digital control system. This condition existed until the Loop 3 MFRV suddenly closed.
D. CAUSE OF EVENT
The cause of the event was failure to maintain installation standards of non-safety related conduit for the MFRV digital control system resulting in primary positioner water intrusion.
E. SAFETY ASSESSMENT
When the reactor tripped, all rods fully inserted. As a result of the trip, a FWI occurred and the AFW system actuated as designed. The unit was stabilized in Mode 3 at normal temperature and pressure. Because the plant responded as designed and there were no complications with plant shutdown, there was no adverse effect on plant safety or the health and safety of the public.
F. CORRECTIVE ACTION
Immediate interim action to inspect and seal the flex conduit to the remaining MFRV positioners was completed for both Unit 1 and Unit 2. Quality Control inspections will be required for conduit installation on critical components to ensure design and installation standards are maintained.
G. ADDITIONAL INFORMATION
- 1) Failed Components:
MFRV Primary Positioner
- 2) Previous Similar Events:
IER 13-14-12 "Water Intrusion into Relay Box Causes Main Feedwater Isolation Valve Closure and Manual Scram"
- 3) Energy Industry Identification System Code:
[JB] -Feedwater/Steam Generator Water Level Control System [JC] -Reactor Protection System [BA] -Auxiliary Feedwater System 3