05000425/LER-2016-002, Regarding Trip on Low-Low Steam Generator Level
| ML16203A337 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 07/21/2016 |
| From: | Pierce C Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-16-0903 LER 16-002-00 | |
| Download: ML16203A337 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(1) 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)(v), Loss of Safety Function |
| 4252016002R00 - NRC Website | |
text
{{#Wiki_filter:Charles R. Pierce Regulatory Affairs Director JUL 2 1 2016 Docket No: 50-425 Southern Nuclear Operating Company, Inc. 40 Inverness Center Parkway Post Office Box 1295 Birmingham. AL 35242 Tel 205.992 7872 Fax 205.992.7601 U-S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Vogtle Electric Generating Plant -Unit 2 Licensee Event Report 2-2016-002-00 SOUTHERN.. \\ NUCLEAR A SOUTHERN COMPANY NL-16-0903 Unit 2 Reactor Trip on Low-Low Steam Generator Level Ladies and Gentlemen: In accordance with the requirements of 10 CFR 73(a)(2)(iv)(A), due to the actuation of a system listed in 10CFR 5073(a)(2(iv)(B), Southern Nuclear Operating Company (SNC) is submitting the enclosed Licensee Event Report, 2-2016-002-00 for Unit 2. This letter contains no NRC commitments. If you have any questions, please contact George Gunn at (706) 848-3596. Rec.c;; ~ed, C. R. Pierce Regulatory Affairs Director CRP/KCW /lac Enclosure: Unit 2 Licensee Event Report 2-2016-002-00 cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Best, Executive Vice President & Chief Nuclear Officer Mr. D. R. Madison, Vice President-Fleet Operations Mr. M. D. Meier, Vice President-Regulatory Affairs Mr. B. K. Taber, Vice President-Vogtle 1 & 2 Mr. B. J. Adams, Vice President-Engineering Mr. G. W. Gunn, Regulatory Affairs Manager-Vogtle 1 & 2 RType: CVC7000 U.S. Nuclear Regulatory Commission Ms. C. Haney, Regional Administrator Mr. R. E. Martin, NRR Project Manager Mr. T. A. Stephen, Senior Resident Inspector
Vogtle Electric Generating Plant-Unit 2 licensee Event Report 2-2016-002-00 Unit 2 Reactor Trip on Low-Low Steam Generator Level Enclosure Unit 2 licensee Event Report 2-2016-002-00
NRCFORM366 U.S. NUCU::AR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 (02-2014) EUmated burden per response to tan!IY \\11th !lis mandatmy cdleaion request. eo 11tu$. l~\\ Repolled lessens learned ara incolpor.Jied lnkl the ~ process ard led badt to inllls!ly. Send oomments reganing burden eslimale to the FOIA, Privacy and lnlormation CollecbOIIS \\.:.-:-.!.) LICENSEE EVENT REPORT (LER) Btandl !f.S F53), U.S. Nuclear RegulatQIY Camiissicn, Washingtort, DC 20555-{)0()1, or by mtemet e-lllidto lntocoileds Resouteinn:.p, and to the Desk Ofiicer, OUic8 ollnlormalioo and Regula!OIY Aftails, NEOB-10202, (3150-(JtGI), Olfic8 of Management and Budget, W~on, DC 20503. ~ a means used to impose an in101111a1iort cdleoiort does oo dsplay a OJileni2y valid OMS contra runber, the NRC may not cxmlud or spmsor, and a pe!SOI'I is not requued to respond to. the inkllmatiort cdleclion.
- 3. PAGE Vogtle Electric Generating Plant-Unit 2 05000425 1 OF 3
- 4. TITLE Unit 2 trip on low-low steam generator level
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED DAY YEAR YEAR l SEQUENTIAl. I REV Y£AR FAGlUTY NM11:
DOCKET NUMBER MONTH NUMBER NO MONTH DAY N/A N/A 07 21 201E FACiliTY riAME DOCKET NUM51:H 05 26 2016 2016 - 002 - 00 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check sl/ thsl spply)
D 20.2201 !bl 0 20.2203(a)(3)(1) D 50.73(a)(2)(1)(C) D 50.73{a)(2}(vil) 1 D 20.2201 (d) 0 20.2203(a)(3)(11) 0 50.73(a)(2)01)(A) 0 50.73{a)(2}(viii)(A) D 20.2203(8)(1 l D 2o.22o3{a)!4l 0 50.73(a)(2){li)(B) 0 50.73{a)(2}(viii)(B) 0 202203{a)(2)(i) 0 50.36(c)(1)(1)(A) 0 50.73(a)(2){111) 0 50.73(8)(2)Qx)(A)
- 10. POWER LEVEL D 202203(a)(2J!ill 0 50,36(c)(1)(11)(A)
[8J 50.73(a)(2)(1v)(A) D 50.73(a)(2}(x) 0 202203(8)(2)(1U) 0 50.36(c)(2) 0 50.73(a)(2)(v)(A) D 73.71(8)(4) 100 D 20.2203(a)(2)(iv) D 50.46(a)(3)(11) 0 50.73(a)(2)(v)(B) 0 73.71(a)(S) 0 20.2203(a)(2)(v) 0 50. 73(a)(2}(1)(A) 0 50.73(a}(2)(v)(C) 0 OTHER 0 20.2203(a)(2)(vi) 0 50.73(a)(2)(1)(B) 0 50.73(a)(2)(v)(D) Specify in All$tract below or In NRC fcnn 366A
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT rELEPHONE NUMBER (lt!t:lur>> ArN Ctx1P)
VogUe Electric Generating Plant, Kevin Walden, Licensing Engineer 706-848-4290
- 13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT CAUSE I SYSTEM I COMPONENT I MANu-I REPORTABlE FACTURER TO EPIX
CAUSE
SYSTEM I COMPONENT MANU* I REPORTABLE FACTURER TO EPtX N/A N/A
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR 0 YES (II yes, complete 15. EXPECTED SUBMISSION DATE)
[8J NO SUBMISSION DATE ABSTRACT (Umit to 1400 spaces, i e., approldmstely 15 single-sp~sd typewritten lines) On May 25, 2016 at approximately 0206 Eastern Daylight Time, the Unit 2 was operating in Mode 1 and 1 00 percent power when the reactor tripped due to low-low level in Steam Generator 1. All control rods fully inserted into the core and all safety systems actuated as designed. The unit was stabilized in Mode 3 with decay heat being removed through the main steam lines to the steam dumps and to the condenser. The low-low level in Steam Generator 1 was due to a human performance error by technicians performing a loop calibration on the Steam Generator 1 level instrumentation. This error resulted in a perceived high level into the Steam Generator Water Level Control system. In response, the Feedwater regulating valve closed which lowered actual level in Steam Generator 1. Because all control rods fully inserted into the core and all the safety systems actuated as designed, this event had no adverse effect on the health and safety of the public, and is of very low safety significance. This event is reportable per 10 CFR 73(a)(2)(iv)(A), due to the actuation of a system listed in 10CFR
- 50. 73(a)(2(iv)(B).
[NRC FORM 3661\\ U.S. NUClEAR REGULATORY COMMISSION 02-21114),......... ~ \\~) LICENSEE EVENT REPORT (LER) CONTINUATION SHEET
- 1. FACtLITY NAME 2.DOCKET Vogtle Electric Generating Plant - Unit 2 05000425
NARRATIVE
A. REQUIREMENT FOR REPORT
- 6. LER NUMBER
- 3. PAGE OF YEAR 1 SEQUENTIAL I REV NUMBER NO.
2 2016 002 00 This report is required per 10 CFR 73(a)(2)(iv)(A) due to an unplanned automatic actuation of the Reactor Protection System (RPS) which generated an 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, 100 percent power
C. DESCRIPTION OF EVENT
3 While operating at 100 percent power, Unit 2 experienced a low-low level alarm in Steam Generator
- 1. This resulted in an automatic RPS actuation due to the low-low level. AFW actuated and Main Feedwater Isolated following the RPS actuation as expected. All rods inserted into the core 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 low-low level in Steam Generator 1 was due to a human performance error by technicians performing a loop calibration on the Steam Generator 1 level Instruments. This error caused the control circuitry to sense that Steam Generator 1 level was slightly above the program level setting. Based on this condition the level control system responded by closing the feed water regulating valve slightly. This human performance error also caused the control circuitry to not be updated with the current Steam Generator 1 level. The combination of the perceived high level in the Steam Generator and the inability to sense actual Steam Generator level drove the feed water regulating valve to continue to close. This caused the actual level to continue to lower until the low-low level setpoint was reached, which triggered the automatic actuation of the RPS and associated safety features.
D. CAUSE OF EVENT
The cause of the event was a human performance error which resulted in the control circuitry for Steam Generator 1 being unable to sense the actual level in the steam generator and the feed water regulating valve being driven closed.
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. NRC FORM ::MeA !Oz.201e)
F. CORRECTIVE ACTION
After this event was identified as being caused by a Human Performance Error, a fleet-wide Human Performance stand down was held. This involved briefings on the importance of HU tool use and error prevention techniques. Additional corrective actions include procedural enhancements for use when performing these types of calibrations, and reconfiguring the controller interface to help prevent this type of error occurring again.
G. ADDITIONAL INFORMATION
(1) Failed Components: (a) None. This was a human performance error. (2) Previous Similar Events: (a) None found (3) Energy Industry Identification System Code: [JCJ-Reactor Protection System [BAJ-Auxiliary Feedwater [SBJ-Main Steam System NRC FOAM :166A (02-201 4) }}