05000461/LER-2011-001, Regarding Postulated Spurious High Pressure Core Spray Initiation Result Unanalyzed

From kanterella
(Redirected from 05000461/LER-2011-001)
Jump to navigation Jump to search
Regarding Postulated Spurious High Pressure Core Spray Initiation Result Unanalyzed
ML11109A008
Person / Time
Site: Clinton Constellation icon.png
Issue date: 04/06/2011
From: Kearney F
Exelon Nuclear
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
U-604011 LER 11-001-00
Download: ML11109A008 (5)


LER-2011-001, Regarding Postulated Spurious High Pressure Core Spray Initiation Result Unanalyzed
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)(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
4612011001R00 - NRC Website

text

Exel1n Nuclear Clinton Power Station 8401 Power Road Clinton, IL 61727-9351 10 CFR 50.73 SRRS 5A. 108 U-604011

April, 6,

2011 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461

Subject:

Licensee Event Report 2011-001-00 Enclosed is Licensee Event Report (LER) No. 2011-001-00: Postulated Spurious High Pressure Core Spray Initiation Result Unanalyzed. This report is being submitted in accordance with the requirements of 10 CFR 50.73.

There are no regulatory commitments contained in this letter.

Should you have any questions concerning this report, please contact A. Khanifar, at (217)-

937-3800.

Respectf ully, F. A. Ke2r~~i Site Vice President Clinton Power Station RSF/blf

Enclosures:

Licensee Event Report 2011-001-00 cc:

Regional Administrator - NRC Region III NRC Senior Resident Inspector - Clinton Power Station Office of Nuclear Facility Safety - IEMA Division of Nuclear Safety

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

, the NRC may e for each b

,lock not conduct or sponsor, and a person is not required to respond to, the digits/characters finformation collection.

3. PAGE Clinton Power Station, Unit 1 05000461 1 OF 4
4. TITLE Postulated Spurious High Pressure Core Spray Initiation Result Unanalyzed
5. EVENT DATE
6. LER NUMBER
7. REPORT DATE
8. OTHER FACILITIES INVOLVED FEUNTA ACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NSEUENTIAL REV MONTH DAY YEAR I

05000 NUMBER NO.

05000______

___________I FACILITY NAME DOCKET NUMBER 02 08 11 2011 001 00 04 06 2011 05000

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

[1 20.2201(b)

[I 20.2203(a)(3)(i)

[I 50.73(a)(2)(i)(C)

El 50.73(a)(2)(vii) 1 [E 20.2201(d)

El 20.2203(a)(3)(ii)

El 50.73(a)(2)(ii)(A)

El 50.73(a)(2)(viii)(A)

El 20.2203(a)(1)

El 20.2203(a)(4) 0 50.73(a)(2)(ii)(B)

[I 50.73(a)(2)(viii)(B)

[I 20.2203(a)(2)(i)

[I 50.36(c)(1)(i)(A)

El 50.73(a)(2)(iii)

El 50.73(a)(2)(ix)(A)

10. POWER LEVEL [E

20.2203(a)(2)(ii)

El 50.36(c)(1)(ii)(A)

El 50.73(a)(2)(iv)(A)

El 50.73(a)(2)(x)

[E 20.2203(a)(2)(iii)

[] 50.36(c)(2)

El 50.73(a)(2)(v)(A)

El 73.71 (a)(4) 96.9 El 20.2203(a)(2)(iv)

[E 50.46(a)(3)(ii)

El 50.73(a)(2)(v)(B)

El 73.71(a)(5)

E3 20.2203(a)(2)(v)

[I 50.73(a)(2)(i)(A)

[I 50.73(a)(2)(v)(C)

El OTHER El 20.2203(a)(2)(vi)

E] 50.73(a)(2)(i)(B)

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

Specify in Abstract below or in actuation of the HPCS pump and reactor core injection. In this scenario, the faults would also impair the capability to shut off the HPCS pump and stop it from injecting water into the core.

Engineering completed an evaluation to address this event and determine additional actions to be taken. The evaluation reviewed the adequacy of the proposed alternative compensatory measures, as compared to the existing required alternate compensatory measures developed for Multiple Spurious Operations (MSO)

(required shiftly Operator rounds, the shiftly transient combustible surveillance, Fire Marshal tours, administrative controls on combustible material and Operations fire brigade training). The evaluation demonstrated that the alternative compensatory measures would not adversely affect the ability to achieve and maintain safe shutdown in the event of a fire and that compliance with 10 CFR 50, Appendix A, General Design Criterion III, and 10 CFR 50.48(a), "Fire Protection," is met.

The station implemented an alternative compensatory action by adding Fire Zone CB-5a as a line item in eSOMS for Operator rounds.

No inoperable equipment or components directly affected this event.

Issue Report 1172335 was initiated to investigate this event and initiate corrective actions.

The NRC Operations Center was notified about this condition via Event Notification 46603 on 2/8/11 at 1406 hours0.0163 days <br />0.391 hours <br />0.00232 weeks <br />5.34983e-4 months <br /> EST.

C. CAUSE OF EVENT

The cause of this event is attributed to a failure to follow procedure AD-CL-101 -1004, "CPS SPECIFIC

'xxxx.xx' NUMBERED PROCEDURES WRITERS GUIDE." The writer's guide establishes performance of disciplinary reviews for specifically coded procedures to ensure the procedures are technically and functionally accurate for all functional areas. Procedure CPS 4003.01 is a procedure that specifically requires an engineering review of changes for impacts. Operations procedure writers did not ensure an engineering review of changes to procedure CPS 4003.01.

D. SAFETY CONSEQUENCES

This event is reportable under the provisions of 10 CFR 50.73(a)(2)(ii)(B) as a condition that resulted in the nuclear power plant being in an unanalyzed condition that degraded plant safety.

The risk significance of an overfill event is low. An overfill event represents a deviation from the intended shutdown strategy and reactor response, but does not result in any immediate core cooling challenges. The steam lines downstream of the SRV discharge flange are not part of the reactor coolant pressure boundary.

Damage to this piping inside the drywell would pressurize the drywell with flashing steam. This steam pressure would act through the drywell Loss of Coolant Accident (LOCA) vents rather than the SRV quenchers and remain bounded by LOCA drywell/containment performance. It would not impact safe shutdown per 10 CFR 50, Appendix R. The continued operation of HPCS will ensure adequate RPV water inventory to maintain adequate fuel temperatures to protect the fuel cladding, and plant capability to operate multiple SRVs will control pressure and dedicated safe shutdown equipment can be controlled from either the Control Room or RSP for a fire in any plant area. Review of calculations related to the quenchers identified that sufficient margin is available to provide assurance that the quenchers will not fail even with LOCA and earthquake loads being considered.

E. CORRECTIVE ACTIONS

Operations procedure writers and supervisor have been briefed on the requirements of procedure AD-CL-101 -1004, and the need to formally request review by other departments, as required.

Operations will validate that procedures related to arc flash concerns have had the cross-disciplinary reviews performed for procedure technical and functional accuracy.

Operations will review a sample of procedures with certain Class Codes related to Engineering, Environmental and In-Service Inspection procedure revisions for the past five years to ensure the cross-disciplinary reviews were performed to ensure the procedure was technically and functionally accurate, if necessary.

A transient and stress analysis of high pressure, high temperature, two phase SRV discharge flow will be completed.

F.

PREVIOUS OCCURRENCES

The condition discussed in this report is similar to NRC URI 2005006-01 identified 6/30/2005. This document discusses postulated fire-induced electrical faults in the control cables and control logic of the HPCS pump and discharge valve from a fire in the Division 3 switchgear room which could result in spurious actuation of the HPCS pump and core injection. These faults could impair the capability to shut off the pump and stop it from continually injecting into the core.

In 2005, the ability to trip the HPCS breaker was still an action in procedure CPS 4003.01, and the ability to shutoff the HPCS pump before it could lead to an overfill event that would lead to SRVs opening as designed to relieve pressure, with water exiting a fully flooded reactor pressure vessel through open SRVs, through the downcomers to the suppression pool was considered achievable by Engineering and Operations.

In the July, 2008 CPS NRC Triennial Fire Protection Inspection (2008006), the inspectors followed-up on the URI, but again concluded that no action was required on the part of the licensee, and that the issue required resolution by NRC Office of Nuclear Reactor Regulation.

G. COMPONENT FAILURE DATA

None