05000382/LER-2009-003, Regarding Multiple Tyco Relay Failures
| ML092310548 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 08/18/2009 |
| From: | Murillo R Entergy Nuclear South, Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| W3F1-2009-0040 LER 09-003-00 | |
| Download: ML092310548 (8) | |
| 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 |
| 3822009003R00 - NRC Website | |
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vmýEnteigy Entergy Nuclear South Entergy Operations, Inc.
17265 River Road Killona, LA 70057-3093 Tel 504 739 6715 Fax 504 739 6698 rmurill@entergy.com Robert J. Murillo Licensing Manager Waterford 3 W3F1-2009-0040 August 18, 2009 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001
Subject:
Licensee Event Report 2009-003-00 Waterford Steam Electric Station, Unit 3 (Waterford 3)
Docket No. 50-382 License No. NPF-38
Dear Sir or Madam:
Entergy is hereby submitting a voluntary Licensee Event Report (LER) 09-003-00 for Waterford Steam Electric Station Unit 3. This report provides the details associated with higher than expected failure rates of normally energized Tyco model E7024PB electro-pneumatic time delay relays produced since 2008. The condition is reported herein as a voluntary report because the issue is of generic interest.
This report contains no new commitments. Please contact Robert J. Murillo at (504) 739-6715 if you have questions regarding this information.
Sir
Attachment:
Licensee Event Report 2009-003-00
W3F1-2009-0040 Page 2 cc:
Mr. Elmo E. Collins, Jr.
Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 NRC Senior Resident Inspector Waterford Steam Electric Station Unit 3 P.O. Box 822 Killona, LA 70066-0751 U. S. Nuclear Regulatory Commission Attn: Mr. N. Kalyanam Mail Stop O-07D1 Washington, DC 20555-0001 Wise, Carter, Child & Caraway ATTN: J. Smith P.O. Box 651 Jackson, MS 39205 Winston & Strawn ATTN: N.S. Reynolds 1700 K Street, NW Washington, DC 20006-3817 Morgan, Lewis & Bockius LLP ATTN: T.C. Poindexter 1111 Pennsylvania Avenue, NW Washington, DC 20004 Louisiana Department of Environmental Quality Office of Environmental Compliance Surveillance Division P. 0. Box 4312 Baton Rouge, LA 70821-4312 R.K. West, lerevents@inpo.org - INPO Records Center
Attachment W3F1 -2009-0040 Licensee Event Report 2009-003-00
NRC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 EXPIRES 8/31/2010 COMMISSION (9-2007)
Estimated burden per response to comply with this mandatory information collection request:
80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the Records Management Branch (T-6 E6), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-LICENSEE EVENT REPORT (LER) mail to bjsl@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202 (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose information collection does not display a currently valid OMB control (See reverse for required number ofnumber, the NRC may not conduct or sponsor, and a person is not required to respond to, the digits/characters for each block) information collection.
- 3. PAGE Waterford 3 Steam Electric Station 05000382 1 OF 5
- 4. TITLE Multiple Tyco Relay Failures
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED S1FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL.I REV MONTH DAY YEAR NUMBER NO NA 05000 Z ~ I ~ I FACILITY NAMEDOKTNME
- - FTTl17-TA=DOCKET NUMBER 07 08 2009 2009 - 003 - 00 08 18 2009 Waterford 3 05000382
- 9. OPERATING MO-DE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
[1 20.2201(b)
EZ 20.2203(a)(3)(i)
EZ 50.73(a)(2)(i)(C)
EZ 50.73(a)(2)(vii)
El 20.2201 (d)
[:1 20.2203(a)(3)(ii)
[]50.73(a)(2)(ii)(A)
[:1 50.73(a)(2)(viii)(A)
[E 20.2203(a)(1)
EZ 20.2203(a)(4)
E 50.73(a)(2)(ii)(B)
EZ 50.73(a)(2)(viii)(B)
E_ 20.2203(a)(2)(i)
[]
50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
Zl 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL
[] 20.2203(a)(2)(ii)
[j 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
[] 50.73(a)(2)(x)
[: 20.2203(a)(2)(iii)
Ej 50.36(c)(2)
El 50.73(a)(2)(v)(A)
E] 73.71 (a)(4) 100 El 20.2203(a)(2)(iv)
[E 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
E 73.71(a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
[7 50.73(a)(2)(v)(C)
S c
OTHER Specify in Abstract below or in 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
REPORTABLE OCCURRENCE There is no reportable occurrence per the reporting requirements outlined in Title 10 of the Code of Federal Regulations. The condition is a voluntary LER to report an issue of generic interest.
INITIAL CONDITIONS This voluntary LER identifies multiple Tyco model E7024PB electro-pneumatic time delay relay failures that have occurred at different initial conditions. Of interest, four of the six failures resulted in Waterford 3 entering into Unplanned Shutdown Limiting Conditions of Operation (LCO) of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
EVENT DESCRIPTION
Waterford 3 has observed a higher than expected failure rate of normally energized Tyco model E7024PB electro-pneumatic time delay relays produced since 2008. Five of six failures were observed on 2008 or newer date code relays and one was observed on a 2004 date code relay, all manufactured by Tyco. Waterford 3 has 33 Tyco model E7024PB time delay relays installed in the plant. The Agastat E7000 series timing relay consists of two basic operating types, On-Delay and Off-Delay. The On-Delay models provide a delay period of contact re-positioning on energization and no time delay upon de-energization. The Off-Delay models provide a delay period of contact re-positioning on de-energization and no time delay upon energization. These relays may be ordered with various electrical characteristics suitable for use specific to each application. The early-in-life failures have been observed on Tyco model E7024PB relays designed as an Off-Delay, 4 pole double throw, 125VDC operating coil, with a time delay range of 0.5 to 5 seconds.
All failed relays were replaced. Post failure bench testing at Waterford 3, Tyco, or independent Failure Analysis has not consistently repeated the failures.
CAUSAL FACTORS A Root Cause Analysis was completed using multiple investigative techniques. Initially a Kepner-Tregoe Problem Solving Analysis was performed. Fault Tree Analysis / Failure Modes Analysis was then performed and the results of these two techniques were reconciled. The results indicated that both methodologies were consistent with each other. The root cause of the early in life relay failures is that manufacturer fabrication was less than adequate. No common specific fabrication issue was identified that would encompass all the relay failures, but the Root Cause Analysis identified six potential fabrication issues that could not be eliminated during the analysis process. These include:
o Mechanical binding of armature and plunger due to foreign material o
Incorrect adjustment of terminal blocks o
Foreign material introduced during the fabrication process obstructing operation of terminal block o Undisclosed relay material change or design change o Incorrect recycle (plunger) spring or spring material o Incorrect adjustment of plunger The six early-in-life normally energized Tyco model E7024PB electro-pneumatic time delay relay failures with serial numbers 04030244, 08040634, 08040636, 08270633, 09030683, and 08350005 can be grouped as follows:
Date code 0804 High Pressure Safety Injection (HPSI) Pump B (09/11/2008), Chemical Volume Control (CVC) Charging Pump A (10/13/2008), and Tyco Relay 08040635 bench test failure (04/13/2009).
Tyco indicated the failures were due to worker error in fabrication and testing (force balance).
Date code 0903 CVC Charging -Pump B (03/13/2009)
Southwest Research Institute (SwRI) performed failure analysis and found foreign material in relay. Corrective Action Request (CAR) issued to Tyco.
Date code 0827 Battery Exhaust Fan A (06/01/2009)
Date codes 0808-0835 were identified by the Tyco 10CFR Part 21 Notification dated 11/21/08 as potentially having an incorrect spring installed during fabrication.
CAUSAL FACTORS CONTINUED Date code 0835 HPSI Pump B (06/22/2009)
The date code 0808 through 0835 relays that were sent back to the vendor per the Part 21 notification, re-certified by the vendor, and returned to Waterford 3 as new relays and the 0835 date code relay failed subsequently. The 08350005 Relay was sent to SwRI for failure analysis with preliminary result that the failure could not be duplicated, but minor foreign material was identified.
Date code 0403 Train B Integrated Emergency Diesel Generator/Engineering Safety Features Test multiple components (05/15/2008)
Bench testing of the failed relay by Electrical Maintenance determined that this normally energized relay would change state if actuated shortly after being energized; however, after an extended period of time (-1 hour) the relay would not change state. This was evaluated as evidence of a heat related failure mechanism specific to this relay. Apparent Cause was determined to be heat degradation in the continuously energized state.
CORRECTIVE ACTIONS
The Root Cause Analysis has identified multiple required corrective actions. The most pertinent are as follows:
O Revised Tyco relay pre-installation testing to include a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> burn in time and cycling the relay 10 times.
O For installed Tyco relays of specific date codes and risk significance, the testing frequency has been increased to proactively assess reliability.
o Implement modification to replace all high priority Agastat E7024 PB relays.
NRC F ORM 366A (9-2007)
SAFETY SIGNIFICANCE
The Waterford 3 EOOS model was used to calculate the risk associated with failure of these 33 relays using the Waterford 3 Revision 4 PRA. The zero maintenance risk for the Revision 4 PRA is 2.779E-06/year. For each of the 33 relay failures, the risk is calculated assuming a failure of the relay (i.e., probability =1.0). Credit for manual actuation of the ESF equipment given the relay failure is assumed to be 1.OE-02, which is conservative given the time available and the simplicity of the action.
Based on the result of this quantification, only four of the relays have a measurable impact on the risk. These relays are the HPSI B pump relay (EG EREL2392-N), the HPSI A pump relay (EG EREL2342-P), the EFW A pump relay (EG EREL2343-D), and the EFW B pump relay (EG EREL2393-C). With conservative credit for manual actuation, the impact on risk for even these relays is insignificant (much less that 1 E-6/yr).
In addition, a case was run with the failure rate of all of the relays increased from 2.50E-05 per demand (which is the generic failure rate from NUREG/CR-6928) to 1.OE-3/demand. The result of this quantification is 2.779E-06/yr or no increase in the base risk.
The Public Health and Safety was not adversely affected by this condition. The relay failures were identified during surveillance or bench testing with the redundant train operable. There were no system or train actuations or initiations resulting from these relay failures. There was not a common mode failure mechanism identified for the relay failures. This condition had no impact on industrial safety or radiological safety. No personnel were injured during these events. The relays are installed outside the radiological controlled areas. No dose was received as a result of these failures.
SIMILAR EVENTS
As stated in the event description, Waterford 3 has observed a higher than expected failure rate of normally, energized Tyco model E7024PB electro-pneumatic time delay relays produced since 2008.
Five of six failures were observed on 2008 or newer date code relays and one 2004 date code relay.
This voluntary LER is an outcome of multiple similar events.
ADDITIONAL INFORMATION
None NRC F ORM 366A (9-2007)