05000275/LER-2013-004, Regarding All Three Unit 1 Emergency Diesel Generators Momentarily Inoperable

Regarding All Three Unit 1 Emergency Diesel Generators Momentarily Inoperable

ML13235A104
Person / Time
Site:	Diablo Canyon
Issue date:	08/22/2013
From:	Allen B Pacific Gas & Electric Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
DCL-13-084 LER 13-004-00
Download: ML13235A104 (5)

LER-2013-004, Regarding All Three Unit 1 Emergency Diesel Generators Momentarily Inoperable

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(v), Loss of Safety Function 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)(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)(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
2752013004R00 - NRC Website

text

Pacific Gas and Electric Company August22,2013 PG&E Letter DCL-13-084 Barry S. Allen Site Vice President Diablo Canyon Power Plant Mail Code 104/6 P. O. Box 56 Avila Beach, CA 93424 805.545.4888 Internal: 691.4888 Fax: 805.545.6445 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 10 CFR 50.73 Docket No. 50-275, OL-DPR-80 Diablo Canyon Unit 1 Licensee Event Report 1-2013-004-00, All Three Unit 1 Emergency Diesel Generators Momentarily Inoperable Dear Commissioners and Staff; In accordance with10 CFR 50.73(a)(2)(ii)(B) and 10 CFR 50.73(a)(2)(v)(D), Pacific Gas and Electric Company (PG&E) submits the enclosed Licensee Event Report (LER). This LER describes Unit 1 being in an unanalyzed condition and a condition that could have prevented fulfillment of a safety function due to human error.

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

All of the corrective actions identified in this letter will be implemented in accordance with the Diablo Canyon Power Plant corrective action program.

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

Sincerely, Barry S. Allen SSZ 1/4040/50570582 Enclosure cc: Thomas R. Hipschman, NRC Senior Resident Inspector Jennivine K. Rankin, NRR Project Manager Steven A. Reynolds, NRC Region IV Diablo Distribution INPO 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.

130 PAGEl Diablo Canyon Power Plant, Unit 1 05000-275 OF 4

4. TITLE All Three Unit 1 Emergency Diesel Generators Momentarily Inoperable

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 FACILITY NAME DOCKET NUMBER 06 23 2013 2013. 004. 00 08 22 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

20.2201(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)

[(] 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)

D 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)

D 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)

[(] 50.73(a)(2)(v)(O)

Specify in Abstract below or in YEAR

6. LER NUMBER I

SEQUENTIAL I NUMBER 2013 -

004 C. Status ofInoperable Structure, Systems, or Components That Contributed to the Event REV NO.

00 3

3. PAGE OF 4

Due to the event reported in NRC EN 49143, the startup 230 kV power source was also inoperable during the restoration activities. On June 24, 2013, at 02:00 PDT, operators restored the 230 kV system to operable status.

I

D. Other Systems or Secondary Functions Affected

None.

E. Method of Discovery

An operator reviewing EDG performance data discovered the reportable condition caused by the error.

F. Operator Actions

At the time of discovery, all offsite and onsite power sources were operable. No actions were required G. Safety System Responses None.

III. Cause of the Problem Pacific Gas and Electric Company (PG&E) determined the cause of this event was an inattentive error by control room operators who placed all EDGs in manual before returning the selector switch to auto. Additionally, the Shift Foreman did not provide oversight as required by plant procedures and the annunciator response procedure did not contain any caution or note to prevent operators from using manual control to shut down all three EDGs concurrently.

IV. Assessment of Safety Consequences

DCPP performed a probabilistic risk assessment and documented the results in a formal calculation for the exposure period. The exposure timeframe started when the second EDG was stopped and ended when the second EDG was placed in auto. DCPP was in this condition for 1 minute and 44 seconds (between 22:01:10 PDT and 22:02:54 PDT, on June 23, 2013). During this time, less than the required minimum two EDGs were available to automatically respond to a DBA.

The calculation showed that both incremental core damage and large early release probabilities were well below their respective acceptance criteria. Therefore, the event is not considered risk significant and did not adversely affect the health and safety of the public. This event was a safety system functional failure.

V. Corrective Actions

A. Immediate Corrective Actions Plant management issued an operations shift order that reinforces guidance and expectations for oversight as stated in plant procedures.

B. Other Corrective Actions PG&E reviewed the personnel performance of the Shift Foreman, Work Control Lead, Balance of Plant Control Operator, and the Control Operator using the accountability process to assess their response. In accordance with plant processes, an action plan will be maintained in the crew notebook as required.

DCPP will revise Departmental Administrative Procedure OPl.DClO, "Conduct of Operations," to enhance Shift Foreman oversight expectations to provide direct supervision and oversight of the control room operators for equipment manipulations on the front control board panels. The revision will also ensure that an adequate prejob brief is performed for similar evolutions.

DCPP will revise Annunciator Response Procedure PK19-04, "12KV SU BUS UV," (startup bus undervoltage) to have sequential steps for placing EDGs in manual and securing them, one at a time, with specific notes or cautions highlighting EDG inoperability when in manual.

VI. Additional Information

A. Failed Components None.

B. Previous Similar Events

None.

C. Industry Reports None.