05000323/LER-2009-003, Re Containment Sump Recirculation Valve Position Interlock Failure Due to Inadequate Testing
| ML093630088 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  (DPR-082) |
| Issue date: | 12/23/2009 |
| From: | Becker J Pacific Gas & Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| DCL-09-094, OL-DPR-82 LER 09-003-00 | |
| Download: ML093630088 (13) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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)(ix)(A) 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)(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 |
| 3232009003R00 - NRC Website | |
text
Pacific Gas and Electric Company J_a_me_s R~llecker Diablo Canyon-7FPo~we""ro"-'Pla=nt,------__
'Site Vice President Mail Code 104/5/601 p. O. Box 56 December 23,2009 PG&E Letter DCL-09-094 u.s. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-323, OL-DPR-82 Diablo Canyon Unit 2 Licensee Event Report 2-2009-003-00 Containment Sump Recirculation Valve Position Interlock Failure Due to Inadequate Testing
Dear Commissioners and Staff:
Avila Beach, CA 93424 805.545.3462 Internal: 691.3462 Fax: 805.545.6445 In accordance with 10 CFR Parts 50.73(a)(2)(i)(B), 50.73(a)(2)(ii)(B),
50.73(a)(2)(v)(D), and 50.73(a)(2)(ix)(A), Pacific Gas and Electric Company is submitting the enclosed licensee event report regarding degradation of the Loss of Coolant Accident recirculation flow path that would have prevented the Residual Heat Removal flow from reaching the containment spray, high head and intermediated head safety injection pumps following alignment to long term recirculation from the containment sump without additional operator actions.
There are no new or revised regulatory commitments in this report.
This event did not adversely affect the health and safety of the public.
- Sincerey,
~'er ddm/2246/50277252 Enclosure cc/enc:
Elmo E. Collins, NRC Region IV Michael S. Peck, NRC Senior Resident Inspector Alan B. Wang, NRR Project Manager Megan Williams, NRC Region IV 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. WolfCreek I
NRC FORM 366 (9-2007)
U.s. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME Diablo Canyon Unit 2
- 4. TITLE
- 2. DOCKET NUMBER 05000323
- 13. PAGE I
1 OF 12 Containment Sump Recirculation Valve Position Interlock Failure Due to Inadequate Testing
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV MONTH FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
DAY YEAR FACILITY NAME DOCKET NUMBER 10 23 2009 2009
- 003
- 00 12 23 2009
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check al/ that apply)
D 20.2201(b)
D 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C)
D 50.73(a)(2)(vii) 6 D
20.2201 (d) 0 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
D 20.2203(a)(1) 0 20.2203(a)(4) 181 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B)
D 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A)
D 50.73(a)(2)(iii) 181 50.73(a)(2)(ix)(A) 1-1-0.-P-O-W-E-R-L-E-V-EL---fD 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) 0 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) 0 50.73(a)(2)(v)(B)
D 73.71(a)(5)
D 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(C)
D OTHER o
D 20.2203(a)(2)(vi)
~ 50.73(a)(2)(i)(B) 181 50.73(a)(2)(v)(D)
Specify in Abstract below or in =
information not being formatted for ready retrieval or use.
That led to a human error by the Engineer having to remember the need to coordinate Rotor 3 with Rotor 1.
Assessment of Safety Consequences
There were safety consequences as a result of this event.
The Unit 1 reactor was maintained in Mode 1, with TS-required equipment operable, as confirmed by a review of the successful surveillance testing performed during the Unit 1 fourteenth and fifteenth refueling outages.
Pacific Gas and Electric Company and the Nuclear Steam Supply System (NSSS) vendor, Westinghouse, performed a limited scope best estimate analysis of the effect of the described condition. From those analyses, it was determined that for a large break LOCA; no significant adverse affects occur as the RCS pressure decreases rapidly, the accumulators inject, and SI system operates to keep the core in a coolable geometry with the RHR pumps alone providing the required SI flow necessary. Therefore, with the availability of the RHR pumps and flow path throughout Cycle 15, there is reasonable assurance that there were no significant adverse consequences resulting from a postulated large break LOCA.
For the small break LOCA conditions a range of breaks were investigated that concluded for five (5) inch and smaller diameter piping breaks the containment spray pumps were not automatically actuated during the injection phase of the accident. Therefore, there is sufficient time from the RWST low level alarm and RHR pump trip point to effectively manually transfer the containment recirculation flow path to the reactor core, with greater than one hour of total time available for
~
I
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL NUMBER REVISION NUMBER Diablo Canyon Unit 2 0 151 0 I 0 I 0 I 3 121 3 2009
- - I 0 I 0 I 3 I -
0 I 0 10 I OF 112 TEXT remote manual and local manual valve operation. A review of the anticipated Unit 2 Cycle 15 radiological conditions at the local manual valve locations found no significant radiological "turn back" condition that would preclude successful
operator actions
Additionally, from the analysis, it was confirmed that for breaks larger than approximately five (5) inch diameter that the containment spray could be actuated, drawing the RWST inventory more quickly. However, the RCS pressure dropped significantly allowing the RHR alone to satisfy the long term recirculation cooling.
Therefore, this event did not adversely affect the health and safety of the public.
PG&E considers this event a Safety System Functional Failure (SSFF). Since it does not result in crossing an NRC PI threshold DCPP will include it with the next routine quarterly PI data submittal.
V.
Corrective Actions
A.
Immediate Corrective Actions
- 1. Engineering confirmed that appropriate testing was performed for all ECCS interlocks prior to Mode 4 entry for Unit 2 following 2R15.
- 2. Engineering confirmed that appropriate tests were performed for all ECCS interlocks for the Unit 1 fifteenth refueling outage.
- 3. An operations summary of the event was published and given to all crews. Included in the summary was a discussion of the importance of knowing the locations of valves identified in the EOPs that might be required to be manually operated and the actuation of MOVs using the contactors at the Motor Control Centers (MCC).
B.
Corrective Actions to Prevent Recurrence (CAPR)
- 1. MP E-53.10V1 has been revised (11/12/09) to include guidance for limit switch setting and rotor coordination.
- 2. Revise MOV maintenance procedures to identify that performance of specific steps requires implementation of MMD M-0000?3-1.
- 3. Revise Calculation V-O? to specify limitations for the use of stroke time calculation in design applications.
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL NUMBER REVISION NUMBER Diablo Canyon Unit 2 o 151 0 I 0 I 0 I 3 12 I 3 2009
- I 0 I 0 I 3 I ~
TEXT C.
Administrative Actions
- 1. Revise PEP V-7B to:
e Have a full performance of the test of every refueling outage,
- Include in the "Discussion" section a statement that the test is not only performed as PMT but also as a test to verify the design function of the interlocks even when no maintenance was performed on the specific tested components.
o Reference this event and order 60020753, and
- Reference AR A0551483, "Evaluate Deferral of STP V-7B Scope."
- 2. Revise AD8.DC58, "Outage Scope Control," and AD8.DC60, "Outage Schedule Preparation," to require that deletions of non-TS driven STPs or PEPs that have been routinely performed during multiple outages be collectively evaluated and reviewed by Engineering, Maintenance, Operations, and Outage Management; and the basis documented prior to deletion from an outage schedule.
- 3. Revise AD13.ID4, "Post Maintenance Testing," to require that any proposed PMT changes due to work scope change be documented in SAP, evaluated and independently reviewed by individuals with adequate technical knowledge, and approved by a supervisor or higher prior to the PMT being rejected.
- 5. Revise Engineering Calculation V-07, Appendix K, to include, specific reference to rotor coordination and to make narrative information easily usable.
VI.
Additional Information
A.
Failed Components None, this condition involved individual switch settings that were capable of functioning but were not properly coordinated to ensure operability.
B.
Previous Similar Events
None were identified at DCPP.
C.
Industry Reports
FACILITY NAME (1)
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION DOCKET NUMBER (2)
YEAR LER NUMBER (6)
SEQUENTIAL NUMBER REVISION NUMBER PAGE (3)
Diablo Canyon Unit 2 0 151 0 I 0 I 0 1 3 121 3 2009
- - 1 0 1 0 1 3 1 -
0 1 0 12 I OF 112 TEXT 390-061026-1, "Licensee Event Report 390-06009 - Containment Spray Valve Interlock," reported an industry condition similar to this event.
The Watts Bar event was similar in that a mis-coordinated rotor resulted in a required function being inoperable. In the Watts Bar event, the function was containment spray during recirculation. The corrective actions at Watts Bar are similar to those taken for this event.
PG&E was not previously aware of this industry event was not previously identified because Watts Bar, INPO and NRC did not publish an operating experience report (e.g. OE, SEN, IN) regarding the issue.