05000255/LER-2011-004, Regarding Turbine-Driven Auxiliary Feedwater Pump Inoperable in Excess of Technical Specification Requirements Due to Unexpected Trip
| ML111890417 | |
| Person / Time | |
|---|---|
| Site: | Palisades  (DPR-020) |
| Issue date: | 07/08/2011 |
| From: | Kirwin T Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PNP 2011-055 LER 11-004-00 | |
| Download: ML111890417 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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 |
| 2552011004R00 - NRC Website | |
text
Entergy Nuclear Operations, Inc.
Palisades Nuclear Plant
~Entergy 27780 Bkie Star Memorial Highway Tel 269 764 2000 Thomas P Kirwin Acting Site Vice President PNP 2011-055 July 08, 2011 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
SUBJECT:
Licensee Event Report 2011-004, Turbine-Driven Auxiliary Feedwater Pump Inoperable in Excess of Technical Specification Requirements Due to Unexpected Trip Palisades Nuclear Plant Docket 50-255 License No. DPR-20
REFERENCES:
10 CFR 50.73
Dear Sir or Madam:
Licensee Event Report (LER) 2011-004 is enclosed. This LER is being submitted in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the plants Technical Specifications.
This letter contains one new commitment and no revisions to existing commitments.
ENO will provide a supplement containing the results of the additional causal evaluation and potential new corrective actions by December 15, 2011.
Sincerely tpk/tad Enclosure: Licensee Event Report 2011-004 CC Administrator, Region Ill, USNRC Project Manager, Palisades, USN RC Resident Inspector, Palisades, USN RC
NRC FORM 366 APPROVED BY 0MB NO. 31 50-01 04 EXPIRES 1013112013 U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
, the NRC may not conduct or sponsor and a person is not required to respond to, the information collection.
(See reverse for required number of digits/characters_for_each_block)
- 3. PAGE PALISADES NUCLEAR PLANT 05000255 1
of 3
- 4. TITLE:
Turbine-Driven Auxiliary Feedwater Pump Inoperable in Excess of Technical Specification Requirements Due to Unexpected Trip
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 05 10 2011 2011 004 00 07 08 2011
- 9. OPERATING MODE II. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
Li 20.2201(b)
Li 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 1 Li 20.2201(d)
Li 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
Li 20.2203(a)(1)
Li 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
Li 50.36(c)(1)(i)(A)
[El 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL Li 20.2203(a)(2)(ii)
Li 50.36(c)(1)(ii)(A)
Li 50.73(a)(2)(iv)(A)
Li 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
[1 50.36(c)(2)
[1 50.73(a)(2)(v)(A)
El 73.71(a)(4)
~
El 20.2203(a)(2)(iv)
[El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5)
~
El 20.2203(a)(2)(v)
Li 50.73(a)(2)(i)(A)
Li 50.73(a)(2)(v)(C)
El OTHER Specify In Abstract below or in Li 20.2203(a)(2)(vi)
~
50.73(a)(2)(i)(B)
Li 50.73(a)(2)(v)(D)12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code Terry Davis (269) 764-2117CAUSE SYSTEM COMPONENT FACTURER REPORTABLE
CAUSE
SYSTEM COMPONENT FACTURER REPORTABLE X
BA TRB E220 Y
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION
~
YES (Ifyes,completel5.EXPECTEDSUBMISSIONDATE)
Li NO DATE 12 15 2011 ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines On May 10, 2011, during routine auxiliary feedwater (AFW) pump Technical Specification (TS) testing, the turbine-driven AFW pump, P-8B, tripped due to the unexpected actuation of the mechanical overspeed trip linkage. Examinations revealed that the knife edge of the trip resetting lever had disengaged from the hand trip lever latch area allowing the trip valve assembly to isolate steam flow to the turbine-driver. The pump had previously passed TS surveillance testing on October 28, 2010, and February 15, 2011.
Post-event troubleshooting efforts and problem analysis revealed grease was applied to the incorrect component on the overspeed mechanical trip linkage, by supplemental contract employees, during maintenance activities performed in the October 2010 refueling outage. Subsequent reviews of operating experience identified additional potential causes for the turbine mechanical overspeed trip linkage to actuate, absent an actual overspeed condition. Therefore, P-8B and its corresponding AFW train may have been inoperable for a period of time longer than the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> allowed by TS 3.7.5.A. Entergy Nuclear Operations, Inc. (ENO) concluded a supplemental detailed evaluation was required to determine the probable cause of the event to enable an accurate assessment of the inoperable time period.
Planned corrective actions include the completion of an additional evaluation to determine the probable cause, enhancements to applicable maintenance procedures and incorporating this event as operating experience into contract supplemental employee human performance briefings.
Due to the ongoing evaluation of the condition, ENO will provide a supplement containing the results of the additional causal evaluation and potential new corrective actions by December 15, 2011.
NRC FORM 366 (10-2010)U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL REVISION YEAR NUMBER NUMBER PALISADES NUCLEAR PLANT 05000255 2011 004 00 2
OF 3
PLANT CONDITIONS
On May 10, 2011, at the time the turbine-driven auxiliary feedwater (AFW) pump (P-8B) tripped, the plant was operating at approximately 99% power.
EVENT DESCRIPTION
The Palisades AFW system [BA] supplies water to the secondary side of the steam generators for reactor decay heat removal when normal feedwater sources are unavailable. The system consists of two electric motor-driven pumps, P-8A and P-8C, and one turbine-driven [TRB] pump [P], P-8B. Any one of the three pumps can supply 100% of the required feedwater flow to both steam generators.
Between October 6 and 22, 2010, during the 1 R21 refueling outage, several maintenance activities were performed on the turbine-driver, and the associated mechanical overspeed trip linkage, of P-8B. On October 28, 2010, P-8B was returned to operable status following satisfactory completion of Technical Specifications (TS) surveillance test, RO-145, Comprehensive Pump Test. The pump was required to be operable at the point of criticality, on October 29, 2010, at approximately 01:05, following the 1 R21 refueling outage. P-8B operated satisfactorily again on February 15, 2011, for the required periodicTS surveillance test, QO-21, Inservice Test.
On May 10, 2011, during TS surveillance test, RO-97, AFW Automatic Initiation Test, P-8B, tripped due to the unexpected actuation of the mechanical overspeed trip linkage allowing the trip valve assembly to isolate steam flow to the turbine-driver. An examination revealed that the knife edge of the trip resetting lever had disengaged from the hand trip lever latch area allowing the trip valve assembly to isolate steam flow to the turbine-driver.
A past operability evaluation identified there was one instance between October 29, 2010, and May 10, 2011, when the hand trip leverand the resetting leverwas disturbed. On February 14,2011, in accordance with TS surveillance test, QO-21, the resetting lever was manually lowered then raised, causing the trip valve assembly to travel from the open to closed to open position (see figure below). This manipulation is performed to verify freedom of movement of the trip valve assembly. A QO-21 post-test check was performed that ensured proper alignment, i.e., no gap, between the resetting lever and the hand trip lever.
No physical manipulations are performed as a part of this post-test alignment check. The alignment check was also performed on May 10, 2010, prior to pump operation for TS surveillance test, RO-97. No discrepancies were identified.U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL REVISION YEAR NUMBER NUMBER PALISADES NUCLEAR PLANT 05000255 2011 004
- - 00 3
OF 3
CAUSE OF THE EVENT
Post-event troubleshooting efforts and problem analysis revealed the actuation of the mechanical overspeed trip linkage was not due to an actual overspeed condition.
It was discovered that grease was applied to the incorrect component on the mechanical overspeed trip linkage, by supplemental contract employees, during maintenance activities performed during the October 2010 1R21 refueling outage.
Insufficient friction, due to the application of grease, between the knife edge of the trip resetting lever and the latch area of the hand trip lever may have allowed the resetting lever to slip off the hand trip lever latch.
Subsequent reviews of operating experience identified additional potential causes for the turbine mechanical overspeed trip linkage to actuate, absent an actual overspeed condition. Other potential causes include improper setup of the trip valve assembly and/or the relaxation of the closing springs.
Therefore, P-8B and its corresponding AFW train may have been inoperable for a period of time longer than the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> allowed by TS 3.7.5.A. Entergy Nuclear Operations, Inc. (ENO) concluded a supplemental detailed evaluation was required to determine the probable cause of the event to enable an accurate assessment of the inoperable time period.
Due to the ongoing evaluation of the condition, ENO will provide a supplement containing the results of the additional causal evaluation and potential new corrective actions by December 15, 2011.
CORRECTIVE ACTIONS TAKEN On May 11, 2011, the mechanical overspeed trip linkage was cleaned of any potential foreign debris, the mechanical overspeed trip linkage was reset, and TS surveillance test, RO-97, was completed satisfactorily. On May 12, 2011, after satisfactory completion of TS surveillance test, QO-21, P-8B was returned to operable status.
CORRECTIVE ACTIONS TO BE TAKEN Planned corrective actions include the completion of an additional evaluation to determine the probable cause, enhancements to applicable maintenance procedures and incorporating this event as operating experience into contract supplemental employee human performance briefings.
ASSESSMENT OF SAFETY CONSEQUENCES
The event is considered to be of low safety significance based on the availability of AFW from at least one alternate AFW pump. AFW flow remained available via operable AFW pumps P-8A and/or P-8C, except for a brief period (<one hour) on April 28, 2011, and again on May 10, 2011, when P-8A or P-8C were inoperable due to being in manual control for testing.
In that instance, operators would have been directed by procedure to recover steam generator level, and could have readily started P-8A or P-8C from the control room. In addition, the ability to manually reset the mechanical overspeed trip linkage of P-8B is proceduralized and considered a simple task that can be executed in a relatively short period of time.
PREVIOUS SIMILAR EVENTS
None