05000255/LER-2007-009, For Palisades, Regarding Automatic Valve in Emergency Core Cooling System Inoperable in Excess of Technical Specification Requirements
| ML080500297 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 02/14/2008 |
| From: | Schwarz C Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 07-009-00 | |
| Download: ML080500297 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(x) |
| 2552007009R00 - NRC Website | |
text
Entergy Nuclear Operations, Inc.
Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043 Tel269 764 2000 February 14, 2008 10 CFR 50e73(a)(2)(i)(B)
U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Palisades Nuclear Plant Docket 50-255 License No. DPR-20 Licensee Event Report 07-009, Automatic Valve in Emerqency Core Coolinq System Inoperable in Excess of Technical Specification Requirements
Dear Sir or Madam:
Licensee Event Report (LER)07-009 is enclosed. The LER describes the discovery that an automatic valve in the emergency core cooling system was inoperable for longer than allowed by Technical Specifications. The occurrence is reportable in accordance with 10 CFR 50,73(a)(2)(i)(B).
Summarv of Commitments This letter contains no new commitments and no revisions to existing commitments, Site vide President Palisades Nuclear Plant Enclosure (1 )
CC Administrator, Region Ill, USNRC Project Manager, Palisades, USNRC Resident Inspector, Palisades, USNRC
ENCLOSURE 1 LER 0'7-009 Automatic Valve in Emergency Core Cooling System Inoperable in Excess of Technical Specification Requirements 3 Pages Follow
LICENSEE EVENT REPORT (LER) 20.2203(aH31(ii) 5OV73(a)(2)(iv)(A) 50.73(a)(2)(x) 202203(a)(2)(iii) 50.36(~)(2) 20.2203(a)(2)Iii) 20.2203(a)(2)(v)
(ECCS). In the event of a postulated loss of coolant accident, CV-3047 is required to close (or remain closed) on receipt of a safety injection signal to ensure that all available safety injection flow is directed to the primary coolant system (PCS).
On November 26,2007, CV-3047 had exceeded its stroke time to close during testing. Pending further troubleshooting, administrative controls were established with the intent to maintain CV-3047 closed. Subsequently, on December 18, 2007, investigation determined that CV-3047, although indicating dosed, was not fully closed.
Technical Specification (TS) Surveillance Requirements (SR) 3.5.2.2 and 3.5.2.5 require that each ECCS automatic valve in the flow path be verified to be in the correct position, and to actuate to the correct position, respectively. Since CV-3047 was not fully closed, it was incapable of meeting SRs 3.5.2.2 and 3.5.2.5.
This condition is reportable in accordance with 10 CFR 5OV73(a)(2)(i)(B) as a condition prohibited by Technical Specifications.
NRC FORM 366 (9-2007)
EVENT DESCRIPTION
IRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION 1.2007)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET On December 18, 2007, during performance of Technical Specification (TS) surveillance testing tc verify the boron concentration in each safety injection tank (SIT) [TK;BP], it was observed that level and pressure in the "C" SIT lowered unexpectedly when the "B" SIT was being drained for its sample. Investigation determined that the "CC" SIT pressure control valve, CV-3047 [PCV;BP],
although indicating closed, was not fully closed, which allowed the "C" SIT to drain when downstream header valves were opened during the "B" SIT sample activity.
CV-3047 is a normally closed boundary valve associated with the emergency core cooling system (ECCS) [BPI. In the event of a postulated loss of coolant accident, CV-3047 is required to close (or remain closed) on receipt of a safety injection signal to ensure that all available safety injection flow is directed to the primary coolant system (PCS) [AB].
- 3. PAGE 2
OF 3
Previously, on November 26, 2007, CV-3047 had exceeded its stroke time to close during testing.
The indicated closing stroke time for CV-3047 was 16.7 seconds versus a test acceptance criterion of 8.6 seconds. Pending further troubleshooting, administrative controls were establishec with the intent to maintain CV-3047 closed, to provide assurance that the safety function for CV-3047 was met.
- 1. FACILITY NAME
'ALISADES NUCLEAR PLANT However, the discovery on December 18, 2007, that CV-3047 was not fully closed in conjunction with the excessive closing stroke time identified on November 26, 2007, provides evidence that CV-3047 may not have been fully closed for that entire period.
- 2. DOCKET 05000255
- 6. LER NUMBER TS Surveillance Requirements (SR) 3.5.2.2 and 3.5.2.5 require that each ECCS automatic valve in the flow path be verified to be in the correct position, and to actuate to the correct position, respectively. Since CV-3047 was not fully closed, it was incapable of meeting SRs 3.5.2.2 and 3.5.2.5. For failure to meet these SRs, SR 3.0.1 specifies that the Limiting Condition for Operation (LCO) is also not met. TS LC0 3.5.2 requires two ECCS trains to be operable.
TS 3.5.2.8 allows one or more ECCS trains to be inoperable for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. With the completion time of TS 3.5.2.B not met, TS 3.5.2.C requires the plant be in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and PCS temperature reduced to < 325 degrees F within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Therefore, the 72-hr completion time of TS 3.5.2.B for restoring ECCS trains to operable status and the subsequent required actions of TS 3.5.2.C were not met. This condition is reportable in accordance with 10 CFR 50,73(a)(2)(i)(B) as a condition prohibited by Technical Specifications.
REV'S'ON NUMBER YEAR RC FORM 366A (9-2007) 2007 009 00 SEQUENTIAL NUMBER
CAUSE OF THE EVENT
VRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION 9-2007)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET Troubleshooting revealed that the air relay gasket in the positioner for CV-3047 had a small tear, which allowed sufficient air pressure to be applied to CV-3047 to hold the valve slightly off its seat The estimated valve position was approximately 0.1 84 inches off the seat, with a nominal full stroke length for this valve of 1 inch. This shaft position is based on positioner signal output gauge readings.
With the position indication for CV-3047 indicating that the valve was in the closed (safety) position, the potential for CV-3047 to be partially open was not recognized. This led to a decision that it was not necessary to lock, seal or otherwise secure CV-3047 in its safety position following the failed stroke test.
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OF 3
CORRECTIVE ACTIONS
- 1. FACILITY NAME PALISADES NUCLEAR PLANT The CV-3047 positioner was repaired, restoring the valve to operable status.
- 2. DOCKET 05000255
- 6. LER NUMBER The aspects of this occurrence regarding acceptable methods for locking valves in the correct position will be reviewed with appropriate personnel.
YEAR
SAFETY SIGNIFICANCE
The event is considered to be of very low safety significance. An analysis was performed which concluded that with CV-3047 in its as-found partially open position, 100% of required ECCS flow to the PCS remained available. Therefore, the condition did not prevent the fulfillment of the safety function of the ECCS System.
2007 009 00 SEQUENTIAL NUMBER
PREVIOUS SIMILAR EVENTS
R ~ V ~ S l O N NUMBER None IRC FORM 366A (9-2007)