05000324/LER-2005-006, Re Voluntary Report - Shutdown of Units 1 and 2 Due to Emergency Diesel Generator Operability Concerns
| ML052850279 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 09/30/2005 |
| From: | Waldrep B Progress Energy Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| BSEP-05-0127 LER 05-006-00 | |
| Download: ML052850279 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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)(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 |
| 3242005006R00 - NRC Website | |
text
Progress Energy SEP 3 0 2005 SERIAL: BSEP05-0127 10 CFR 50.73 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Brunswick Steam Electric Plant, Unit Nos. 1 and 2 Docket Nos. 50-325 and 50-324/License Nos. DPR-71 and DPR-62 Voluntary Licensee Event Report 1-2005-006 Ladies and Gentlemen:
In accordance with the Code of Federal Regulations, Title 10, Part 50.73, Carolina Power
& Light Company, now doing business as Progress Energy Carolinas, Inc., submits the enclosed Voluntary Licensee Event Report.
Please refer any questions regarding this submittal to Mr. Edward T. O'Neil, Manager - Support Services, at (910) 457-3512.
Sincerely, B. C. WalAmep Plant General Manager Brunswick Steam Electric Plant MAT/mat
Enclosure:
Voluntary Licensee Event Report Progress Energy Carolinas, Inc.
Brunswick Nuclear Plant P.O. Box 10429 Southport, NC 28461
Document Control Desk BSEP 05-0127 / Page 2 cc (with enclosure):
U. S. Nuclear Regulatory Commission, Region II ATTN: Dr. William D. Travers, Regional Administrator Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, GA 30303-8931 U. S. Nuclear Regulatory Commission A1TN: Mr. Eugene M. DiPaolo, NRC Senior Resident Inspector 8470 River Road Southport, NC 28461-8869 U. S. Nuclear Regulatory Commission ATTN: Ms. Brenda L. Mozafari (Mail Stop OWFN 8G9) (Electronic Copy Only) 11555 Rockville Pike Rockville, MD 20852-2738 Ms. Jo A. Sanford Chair - North Carolina Utilities Commission P.O. Box 29510 Raleigh, NC 27626-051
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 06/3012007 (6-2004)
Esifeted burden per Hesnse to comply Wh Itis nendatory inforeaton ofdleecfin request 50 han. Repouled lessons learned awe in~ompoeted kwt tIe licensing voces and Jed beck to LICENSEEEVENTtREPORTy(LER) iy.
Send con..
lnts garing tbude estimme tD the Recordbo and FOIAAliacy Seree LICESEEEVET RPOR (LR)Branchi (17-5 112 U.S.
"~ear Rlegulatory Oxnrnisson, Washington, DC 205554000,orb (See reverse for required number of Bac Tnemt e4-ne 6D Woootsnrc.
a tie Desk Oc, Office of InrtonTron and digitscharacters or each block)
Regdatory Mar% NEOB-10202 (3150 0104), Office o Managerni and Budget Washin DC 20503.
a ureans used lo krpose an inkmn.on colection does not dsplay a ctJnt*y Vaid OMN ctrd nmber he ftNRC nay rint cnduct or spoMo, and a person Is nit r"qred to respond ethe irbntebon collectin
- 1. FAClLrY NAME
- 2. DOCKET NUMBER
- 3. PAGE Brunswick Steam Electric Plant (BSEP), Unit 1 05000325 1 OF S
- 4. TITLE Voluntary Report - Shutdown of Units 1 and 2 Due to Emergency Diesel Generator Operability Concerns
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILMES INVOLVED MONTH DAY lYEAR YEAR lSEQUENTAL l MONTHDAY YEAR FACIUTY NAME DOCKET NUMBER YER NUMB ER O
MNHDY BSEP, Unit 2 1
05000324 08 06 l 2005 006 00 9
30 2005 FACIULTY NAME DOCKET NUMBER
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITFED PURSUANT TO THEREQUIREMENTS OF 10 CFR §: (Check one or more) 1l 20.2201 (b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C) 0 50.73(a)(2)(vii) 0 20.2201 (d) 0 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) o 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B) 0 20.2203(a)(2)(i) 0 50-36(c)(1)(i)(A)
E 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL 0
20.2203(a)(2)(ii) 0 50.36(c)(1)(ii)(A) a 50.73(a)(2)(iv)(A) 0 50.73(a)(2)(x) 26 0
20.2203(a)(2)(iii)
D 50.36(c)(2) 0 50.73(a)(2)(v)(A) 0 73.71(a)(4) o 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii) 0 50-73(a)(2)(v)(B) 0 73.71(a)(5) o 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C) 0 OTHER Spec~ifIn Ab stract below 0
20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D) or in NRC 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
Mark A. Turkal, Lead Engineer -Licensing (910) 457-3066CAUSE SYSTEM COMPONENT
=
MANU REPORTABLE
CAUSE
SYSTEM COMANU-REPORTABLE IFACTURER TO EPIX f
FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MO DAY YEAR SUBMISSION YES (if yes, complete EXPECTED SUBMISSION DATE).
X NO DATE A0.: I n~l I u toII 10 I KspaCeS, ie., approyimateiy I 5 slngle-spaceo zypewnuen linesj On August 6, 2005, Units 1 and 2 were shutdown due to operability concerns potentially affecting the site's four Emergency Diesel Generators (EDGs). Unit 1 entered Mode 3 at 0531 hours0.00615 days <br />0.148 hours <br />8.779762e-4 weeks <br />2.020455e-4 months <br /> and Unit 2 entered Mode 3 at 0446 hours0.00516 days <br />0.124 hours <br />7.374339e-4 weeks <br />1.69703e-4 months <br />. The EDG operability was questioned due to concerns that the setpoint for the installed EDG differential overcurrent protective devices (i.e., 87DP relays) was not appropriate.
Subsequently, it was determined that the setpoint for the 87DP relays, while not optimal, did not result in the EDGs being inoperable. As such, reporting of this condition is considered voluntary.
The root cause of this event is replacement of the EDG 87DP differential overcurrent relays, in 1982, without adequate confirmation that the trip setting of the new model was appropriate. This reduced the margin between the 87DP relay trip setpoint and the normal operating current, thereby reducing the EDGs' tolerance to electrical disturbances.
The existing 87DP relays were replaced with new solid state relays with increased margin to the operating current.
NRC FORM 366 (6-2004)
(If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)1982 modification, the margin between the normal operation of the exciter (i.e., 14 to 16 amps) and the setpoint of the 87DP relays is so small that minor perturbations are sufficient to cause actuation of the 87DP relay.
Although the revised 87DP relay setpoint affected EDGs' tolerance for electrical disturbances, EDG reliability remained very high. Since 1982, there have been over 1,000 EDG start demands with a demonstrated EDG start reliability of 99.15 percent. This demonstrates that the 87DP relays would not inadvertently trip without an additional electrical perturbation in its EDG system. Therefore, it is concluded that this condition did not render the EDGs inoperable.
SAFETY ASSESSMENT
The safety significance of this condition is considered minimal.
Based on preliminary information from the root cause investigation team, this design issue was conservatively considered to be a potential common cause failure, the EDGs were declared inoperable, and the units shutdown. This allowed for the relays to be replaced with upgraded relays that restored more appropriate operating margin. Further investigation of the issue concluded that each individual relay would not inadvertently trip without an additional electrical perturbation in its EDG system. Therefore, the EDGs were not susceptible to a common cause failure associated with the 87DP relay margin issue and the setpoint for the 87DP relays, while not optimal, did not result in the EDGs being inoperable.
The EDGs provide a safety significant function in the event of a loss of offsite power. However, the safety significance of this design issue is considered to be very minimal due to the proven reliable performance of the relays and the need for an additional random failure in order to cause an inadvertent EDG trip.
CORRECTIVE ACTIONS
The existing 87DP relays were replaced with new solid state relays with increased margin to the operating current.
PREVIOUS SIMILAR EVENTS
This event is associated with a design deficiency introduced in 1982. Therefore, corrective actions associated with more recent design-related issues could not reasonably be expected to prevent this occurrence.
COMMITMENTS
No regulatory commitments are contained in this report.