05000275/LER-2013-003-01, Regarding Actuation of Six Emergency Diesel Generators Due to Loss of Offsite Power

Regarding Actuation of Six Emergency Diesel Generators Due to Loss of Offsite Power

ML13291A124
Person / Time
Site:	Diablo Canyon
Issue date:	10/17/2013
From:	Allen B Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-13-101 LER 13-003-01
Download: ML13291A124 (5)

LER-2013-003, Regarding Actuation of Six Emergency Diesel Generators Due to Loss of Offsite Power

Event date:
Report date:
Reporting criterion:	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)(iv)(A), System Actuation 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
2752013003R01 - NRC Website

text

Pacific Gas and Electric Company October 17, 2013 PG&E Letter DCL-13-101 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Barry S. Allen Site Vice President 10 CFR 50.73 Licensee Event Report 1-2013-003-01, Actuation of Six Emergency Diesel Generators due to Loss of Offsite Power Dear Commissioners and Staff; Diablo Canyon Power Plant Mail Code 104/6 P. 0. Box 56 Avila Beach, CA 93424 805.545.4888 Internal: 691.4888 Fax: 805.545.6445 Pacific Gas and Electric Company (PG&E) submits the enclosed Licensee ~vent Report (LER) supplement for the valid actuation of all six safety-related emergency diesel generators due to loss of 230 kV offsite power. Both Units 1 and 2 were impacted by this event. PG&E is submitting this LER supplement in accordance with 10 CFR 50. 73(a)(2)(iv)(A). All systems operated as designed with no problems observed.

PG&E makes no new or revised regulatory commitments (as defined by NEI 99-04) in this report.

This event did not adversely affect the health and safety of the public.

Sincerely, v5J5.1/d.-

Barry S. Allen ssz1 /4040/50570450 Enclosure cc: Thomas R. Hipschman, NRC Senior Resident Inspector Jennivine K. Rankin, NRR Project Manager Steven A. Reynolds, NRC Region IV IN PO Diablo Distribution A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• San Onofre

• South Texas Project

• Wolf Creek

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)

, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.

3. PAGE Diablo Canyon Power Plant, Unit 1 05000-275 1 OF 4

4. TITLE Actuation of Six Emergency Diesel Generators due to Loss of Offsite Power

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED YEAR ISEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.

MONTH DAY YEAR Diablo Canyon Unit 2 05000-323 FACILITY NAME DOCKET NUMBER 06 23 2013 2013. 003. 01 10 17 2013

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §:(Check all that apply)

D 20.2201 (b)

D 20.2203(a)(3)(i)

D 50.73(a)(2)(i)(C)

D 50. 73(a)(2)(vii) 1 D 20.22o1(d)

D 20.2203(a)(3)(ii)

D 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A)

D 20.2203(a)(1)

D 20.2203(a)(4)

D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(2)(i)

D 50.36(c)(1)(i)(A)

D 50. 73(a)(2)(iii)

D 50. 73(a)(2)(ix)(A)

10. POWER LEVEL D 20.2203(a)(2)(ii)

D 50.36(c)(1 )(ii)(A)

[{] 50.73(a)(2)(iv)(A)

D 50. 73(a)(2)(x)

D 20.2203(a)(2)(iii)

B 50.36(c)(2)

D 50.73(a)(2)(v)(A) 0 73.71(a)(4) 100 D 20.2203(a)(2)(iv) 50.46(a)(3)(ii)

D 50.73(a)(2)(v)(B)

D 73.71(a)(5)

D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A)

D 50.73(a)(2)(v)(C)

D OTHER D 20.2203(a)(2)(vi)

D 50.73(a)(2)(i)(B)

D 50.73(a)(2)(v)(D)

Specify in Abstract below or in YEAR

6. LER NUMBER I

SEQUENTIAL I NUMBER 2013

• 003 C. Status oflnoperable Structure, Systems, or Components That Contributed to the Event None.

D. Other Systems or Secondary Functions Affected

None.

E. Method of Discovery

REV NO.

01 3

3. PAGE OF 4

Licensed plant operators immediately recognized the event by alarms and indications received in the control room.

F. Operator Actions

On June 23, 2013, operators restored the Unit 1 and Unit 2 EDGs, respectively, to standby service. The 230 kV system was declared operable on June 24, 2013, at 02:00 PDT.

G. Safety System Responses All Unit 1 and Unit 2 EDGs started as designed with no problems observed.

III. Cause of the Problem A. Immediate Cause PG&E determined that on June 23, 2013, starting at 19:09 PDT, several insulator flashovers at Morro Bay Power Plant (MBPP) Switchyard resulted in a wide-spread outage to the greater San Luis Obispo, California area. Heavy fog and precipitation in the area caused insulator flashovers on 115 kV and 230 kV circuit breaker disconnect switches. This caused the sustained loss of key transmission facilities which led to the loss of the 230 kV offsite power source to DCPP.

B. Cause

Degraded insulation, contamination, and weather issues caused the insulation flash-over.

IV. Assessment of Safety Consequences

The 230 kV startup power is a standby system and its loss was due to a degraded condition at an offsite switchyard. This event did not create a transient at the plant. A Significance Determination Process evaluation allows taking credit for the actual plant configuration at the time of an event. With the successful start of all EDGs upon the loss of startup power, the vital AC power supply to all emergency core cooling system loads would have been maintained. A bounding analysis was performed and resulted in an incremental core damage and incremental large early release probabilities that were well below their respective acceptance criteria.

V. Corrective Actions

A. Immediate Corrective Actions The adverse weather cleared and the system restored to service, restoring the 230 kV system.

B. Other Corrective Actions Equipment external to DCPP caused the event. Therefore, DCPP has no other corrective actions related to the

VI. Additional Information

A. Failed Components None.

B. Previous Similar Events

On May 12,2007, at 10:25 PDT, during a refueling outage at DCPP, with Unit 1 in no Mode (core offloaded to the spent fuel pool) and Unit 2 in Mode 1 at approximately 100 percent power, an EDG system actuation was initiated on loss of230 kV startup power supply due to an offsite transmission system non-ceramic insulator failure resulting in a phase to phase short and unanticipated protective relay response. Two Unit 1 EDGs started and loaded to provide onsite power. Unit 1 had one EDG and auxiliary offsite power cleared for maintenance. All three Unit 2 EDGs started as required but did not load since all associated buses remained energized by auxiliary power. At 14:30 PDT, Operators restored startup power to the site. At 15:09 PDT, operators made a nonemergency event notification (EN 43360) in accordance with 10 CFR 50.72(b)(3)(iv)(A). Corrective actions included the resetting of the startup power protection relays to establish a time delay and replacing non-ceramic insulators in the 230 kV supply to DCPP.

C. Industry Reports None.