05000323/LER-2012-001, Regarding Failure to Meet Emergency Diesel Generator Technical Specifications

Regarding Failure to Meet Emergency Diesel Generator Technical Specifications

ML12290A674
Person / Time
Site:	Diablo Canyon
Issue date:	10/16/2012
From:	Allen B Pacific Gas & Electric Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
DCL-12-096 LER 12-001-00
Download: ML12290A674 (5)

LER-2012-001, Regarding Failure to Meet Emergency Diesel Generator Technical Specifications

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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)(ii)(8) 10 CFR 50.73(a)(2)(viii)(8) 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)(8) 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(8)
3232012001R00 - NRC Website

text

__ Pacific Gas and

~&~ Electric Company October 16, 2012 PG&E Letter DCL-12-096 Diablo Canyon Power Plant PO. Box 56 Avila Beach, CA 93424 800.545.6000 u.s. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 10 CFR 50.73 Docket No. 50-323, OL-DPR-82 Diablo Canyon Unit 2 Licensee Event Report 2-2012-001-00, Failure to Meet Emergency Diesel Generator Technical Specifications

Dear Commissioners and Staff:

Pacific Gas and Electric Company (PG&E) is submitting the enclosed Licensee Event Report (LER) regarding the discovery of a broken emergency diesel generator fuel oil booster pump drive belt and subsequent failure to meet plant technical specifications. PG&E is submitting this LER in accordance with 10 CFR 50.73(a)(2)(i)(B) and 10 CFR 50.73(a)(2)(v)(D).

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, Barry S. Allen Site Vice President wrl8/6980/50507816 Enclosure cc/enc:

Elmo E. Collins, NRC Region IV Laura H. Micewski, Acting NRC Senior Resident Inspector Joseph M. Sebrosky, NRR Senior Project Manager INPO 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 (10-2010)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 LICENSEE EVENT REPORT (LER)

(See reverse for required number of digits/characters for each block)

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

1. FACILITY NAME Diablo Canyon Power Plant, Unit 2

4. TITLE

2. DOCKET NUMBER 05000-323

3. PAGE 1 OF 4 Failure to Meet Emergency Diesel Generator Technical Specifications

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 08 18 2012 2012 - 001 -

00 10 16 2012

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)

D 50.73(a)(2)(ii)(8)

D 50.73(a)(2)(viii)(8)

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)

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)

D 50.36(c)(2)

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

D 73.71(a)(4)

D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii)

D 50.73(a)(2)(v)(8)

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

10. POWER LEVEL 100 D 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(8) 0 50.73(a)(2)(v)(D)

Sp~cify in Abstract below or In YEAR

6. LER NUMBER I

SEQUENTIAL I NUMBER 2012 -

001 REV NO.

00 3

3. PAGE OF prevented pump sheave rotation that resulted in the belt snapping during coast-down on August 3, 2012, at l304 PDT, following EDG 2-3's satisfactory performance ofDCPP Surveillance Test Procedure (STP) M-9A, "Diesel Engine Generator Routine Surveillance Test."

On August 20,2012, DCPP Maintenance personnel replaced the FOBP and its drive belt. On August 21,2012, at 0330 PDT, PG&E declared EDG 2-3 operable. PG&E failed to meet TS 3.8.1, Condition B, "One DG inoperable," because EDG 2-3 was not returned to operable status within the required 7-day completion time for unplanned maintenance after EDG 2-3 belt and FOBP failure following the test run on August 3,2012, at l304 PDT.

4 During the time between August 3,2012, at l304 PDT, and August 21,2012, at 0330 PDT, EDG 2-2 was taken out of service and declared inoperable twice to perform surveillance testing. However, EDG 2-2 was still available for use via manual operator action. For those periods that EDG 2-2 was declared inoperable, DCPP Unit 2 only had one operable EDG, when two are required to be operable to perform the designed safety function of providing vital emergency power. This condition would have prevented the fulfillment of the EDG's designed safety function of mitigating the consequences of a DBA.

C. Status of Inoperable Structure, Systems, or Components That Contributed to the Event None.

D. Other Systems or Secondary Functions Affected

None.

E. Method of Discovery

The DCPP Unit 2 Operations turbine building watch discovered the broken EDG 2-3 FOBP belt.

F. Operator Actions

DCPP Operators entered TS 3.8.1, "AC Sources - Operating;" declaring EDG 2-3 inoperable.

G. Safety System Responses None.

III. Cause of the Problem The EDG 2-3 FOBP seized because the vendor-recommended drive belt tension caused excessive side loading and shaft skewing. The drive belt broke because the FOBP seized, preventing sheave rotation, resulting in the drive belt snapping during coast-down ofEDG 2-3 following surveillance testing.

IV. Assessment of Safety Consequences

6. LER NUMBER YEAR I SEQUENTIAL I NUMBER 2012

• 001 REV NO.

00 4

3. PAGE OF PG&E's quantitative risk analysis for the 18 days between the time EDG 2-3 was last successfully run on August 3,2012, and the time when EDG 2-3 was declared operable on August 21,2012, after replacing the FOBP and its drive belt, concluded that the incremental conditional core damage probability was less than the 1.0E-06 risk significance threshold. This event was a Safety System Functional Failure, but it is not considered risk significant and did not adversely affect the health and safety of the pUblic.

V. Corrective Actions

A. Immediate Corrective Actions On August 20,2012, DCPP Maintenance personnel replaced the FOBP and its drive belt.

B. Other Corrective Actions

1) DCPP will reduce the EDG 2-3 drive belt tension specification in procedure MP M-21.7B, "Diesel Engine 2-3 Fuel Oil Booster Pump," to a lower vendor-approved deflection force value.

2) DCPP will establish a periodic replacement strategy for the FOBP.

VI. Additional Information

A. Failed Components

1) The EDG 2-3 FOBP.

2) The EDG 2-3 FOBP drive belt.

B. Previous Similar Events

None. 4