05000498/LER-1917-001, Regarding Failure of a Timing Relay During a Technical Specification Surveillance
| ML17131A353 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 05/11/2017 |
| From: | Connolly J South Texas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NOC-AE-17003479, STI: 34494823 LER 17-001-00 | |
| Download: ML17131A353 (9) | |
| 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)(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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation |
| 4981917001R00 - NRC Website | |
text
South Texas Project Electric Generating Station P.O. Box 289 Wadsworth, Texas 77483 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Unit 1 May 11, 2017 NOC-AE-17003479 10 CFR 50.73 Docket No. STN 50-498 Licensee Event Report 2017-001-00 Unit 1 Failure of a Timing Relay During a Technical Specification Surveillance Pursuant to 10 CFR 50.73(a)(2)(i)(B), STP Nuclear Operating Company (STPNOC) hereby submits the attached South Texas Project (STP) Unit 1 Licensee Event Report (LER) 2017-001-00 for a condition prohibited by Technical Specifications.
The event was of very low risk significance and no radioactive release occurred; therefore, there was no adverse effect on the health and safety of the public.
There are no commitments in this letter.
If there are any questions, please contact Rafael Gonzales at (361) 972-4779 or me at (361} 972-7344.
rjg
Attachment:
Unit 1 LER 2017-001-00 James Connolly Site Vice President STI: 34494823
NOC-AE-17003479 Page 2 of 2 cc:
(paper copy)
Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 East Lamar Boulevard Arlington, TX 76011-4511 Lisa M. Regner Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North (O8H04) 11555 Rockville Pike Rockville, MD 20852 NRC Resident Inspector U. S. Nuclear Regulatory Commission P. O. Box 289, Mail Code: MN116 Wadsworth, TX 77483 (electronic copy)
Morgan, Lewis & Bockius LLP Steve Frantz, Esquire Paul Bessette U.S. Nuclear Regulatory Commission Lisa M. Regner NRG South Texas LP Mark Walker Jim von Suskil Skip Zahn CPS Energy Kevin Pollo Cris Eugster L. D. Blaylock City of Austin Elaina Ball John Wester Texas Dept. of State Health Services Helen Watkins Robert Free
NRC FORM 366 (04-2017)
NRC FORM 366 (04-2017)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
LICENSEE EVENT REPORT (LER)
(See Page 2 for required number of digits/characters for each block)
(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 1. FACILITY NAME South Texas Unit 1
- 2. DOCKET NUMBER 05000498
- 3. PAGE 1 OF 7
- 4. TITLE Unit 1 failure of a timing relay during a Technical Specification surveillance
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.
MONTH DAY YEAR FACILITY NAME N/A DOCKET NUMBER N/A 03 10 2017 2017
- - 001
- - 00 05 11 2017 FACILITY NAME DOCKET NUMBER N/A N/A
- 9. OPERATING MODE 1
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x)
- 10. POWER LEVEL 100 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C) 73.77(a)(1) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D) 73.77(a)(2)(i) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 73.77(a)(2)(ii) 50.73(a)(2)(i)(C)
OTHER Specify in Abstract below or in summary of the event During a Technical Specification surveillance, the as-found operating time (3.295 seconds) of a timing relay (Undervoltage Agastat Timing Relay, model number ETR14D3A004, made by TE Connectivity, system identifier EB, component identifier 62), installed in a safety related 4160 kV switchgear, was greater than the Technical Specification allowable value equal to or less than 1.93 seconds. The performers of the surveillance measured the as-found test value and it was greater than the Technical Specification allowable value. The Control Room Unit Supervisor consulted with the Electrical Maintenance Supervisor and directed the performers to adjust the relay component as allowed by the procedure, and continue with the test.
Before continuing the surveillance, an inspection of the testing equipment was performed to ensure the equipment was functioning correctly. No issues were found and no changes were made to the testing equipment. The maintenance personnel retested the relay timing, without adjustment, and the result was 1.902 seconds. Due to the change in value, an additional test was performed with a result of 1.766 seconds, which was within the prescribed as-left procedure acceptance criteria of 1.715 to 1.785 seconds. Additional re-tests were performed with the same results, (i.e., a value of 1.766 seconds) obtained. Contrary to Control Room Unit Supervisors directions, during relay retesting, no adjustments were made to the timing relay.
The Surveillance Test was completed and logged as satisfactory at 1202 on March 10, 2017, and the component was declared Operable.
Page 3 of 7 (04-2017)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 3. LER NUMBER South Texas Unit 1 05000-498 YEAR SEQUENTIAL NUMBER REV NO.
2017
- - 001
- - 00
E. Method of discovery
On March 14, 2017, an STP engineer completed a review of the condition report documenting the surveillance test for the relay and determined that the relay reliability was questionable. This was based on the relay timing found outside Technical Specification limits and returned to Operable status with no adjustments. The Control Room was contacted and, based on the System Engineers analysis, the Unit 1 Shift Manager determined that the relay should not have been declared Operable on March 10 and declared it inoperable on March 14, 2017 at 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />. Technical Specification 3.3.2, Action 20A, was entered.
The Shift Manager determined that the relay should have remained Inoperable on March 10 until replaced. Technical Specification 3.3.2, Action 20A, requires the channel to be placed in the tripped condition within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The failed undervoltage timing relay was subsequently replaced, satisfactory completion of surveillance test was performed, and the component was declared Operable.
II.
Event-Driven Information A. Safety Systems that Responded This event did not initiate any automatic or manual safety system responses.
B. Duration of Safety System Inoperability
The failed relay was determined to be inoperable per Technical Specifications for approximately 99 hours0.00115 days <br />0.0275 hours <br />1.636905e-4 weeks <br />3.76695e-5 months <br /> prior to discovery. The failed component was discovered as a result of reviewing surveillance test results. Following discovery, the relay was replaced and the channel declared operable within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Based on the last successful surveillance test, the last time the equipment was determined to be capable of performing its safety function is September 22, 2016.
C. Safety Consequences and Implications of the Event During the event, the condition of the system was in a 2 out of 4 logic scheme. Protection for an under voltage condition remained intact for a 2 out of 3 logic, and thus maintained the safety function of the system. If an actual undervoltage condition occurred, the other relays would have performed as designed.
The event was of very low risk significance and no radioactive release occurred; therefore, there was no adverse effect on the health and safety of the public.
Page 4 of 7 (04-2017)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 3. LER NUMBER South Texas Unit 1 05000-498 YEAR SEQUENTIAL NUMBER REV NO.
2017
- - 001
- - 00 III.
Cause of the Event
Based on the conditions identified and using information collected during discussions with the relay manufacturer subject matter expert, the cause of the component failure is not known. The relay was retained following the event, and inspected with satisfactory results. The failure could not be recreated, and the failure mode and mechanism is not known.
The causes for the event were the following:
- 1. Unidentified Material Condition with the failed component (i.e. relay)
- 2. Less than adequate questioning attitude by Electrical Maintenance Personnel
- 3. Less than adequate questioning attitude by Operations Personnel The start of this event consisted of the undervoltage relay as-found operating time being outside the Technical Specification required value. After retesting, the surveillance test timing improved as observed in subsequent retests. The failed condition could not be recreated upon further testing.
The Electrical Maintenance Supervisor did not exhibit sufficient questioning attitude when consulted on this task. The relay did not exhibit the reliability to perform within limits through the next surveillance interval, and this was not recognized. Though the electricians did request clarification from the supervisor as expected, a proper questioning attitude from the supervisor would have determined that further expertise was needed to proceed. In addition, a misinterpretation of the procedure allowed the actions as performed, but the procedure intent was not maintained.
In addition, the Control Room staff displayed an inadequate questioning attitude regarding the adverse performance of the relay. When the information was shared with the Control Room that no adjustment was made to the timing relay, both individuals should have confirmed adequate information was collected to ensure that it was appropriate to proceed with closing out the surveillance rather than simply agreeing with the results of the completed test.
Page 5 of 7 (04-2017)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 3. LER NUMBER South Texas Unit 1 05000-498 YEAR SEQUENTIAL NUMBER REV NO.
2017
- - 001
- - 00 IV.
Corrective Actions
The Table 1 below contains the corrective actions planned as a result of the event:
Table 1: Corrective Actions
Corrective Actions
Description Status 1
Relay was replaced and Surveillance Test completed Satisfactory. (Relay replaced by PM WAN 560042)
Complete 2
Perform one on one sessions with EM personnel involved in this event to determine the reason for the shortfall on questioning the reliability of the subject relay device and any other corrective actions required to include coaching opportunities.
Complete 3
Perform coaching session with individuals involved to ensure clear understanding of 0POP01-ZO-0011 procedure requirements In process 4
Discuss event and refresh on procedure requirements of 0POP01-ZO-0011 with all Licensed Operations Personnel In process Page 6 of 7 (04-2017)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 3. LER NUMBER South Texas Unit 1 05000-498 YEAR SEQUENTIAL NUMBER REV NO.
2017
- - 001
- - 00 V.
Previous Similar Events
A review of similar events at STP was performed by reviewing the STP Corrective Action Program and Licensee Event Reports submitted for the previous 10 years. The review concluded that there have been many occurrences where the as-found condition of this or similarly functioning timing relays were found out of acceptance criteria or outside Technical Specification criteria. However all events involved the old model E7000 timers. It is important to note that the older model relays are diaphragm type designs, while the new relay timers are solid state designs. Since these timers were replaced (starting in 2012) this condition is the first case of its kind. In all occasions identified, the proper notifications and corrective actions were performed.
A search for License Event Reports was performed that focused on events deemed similar reportable under 50.73(a)(2)(i)(B). Several events were found to meet this criteria, but none were directly applicable to this event.
VI.
Additional Information
The discovery date is March 14, 2017 when Unit 1 discovered the need to perform a reportability evaluation on the event. The event date is March 10, 2014, the date when the relay failed to pass the surveillance test. The report date is May 11, 2017, within 60 days after discovery of the event, as required per 10 CFR 50.73(a)(1).
Dates and approximate times of occurrences
3/10/17 1045: Surveillance Test commenced for the Unit 1 E1B undervoltage relay (Relay declared inoperable for planned testing).
3/10/17: Electricians initial as-found measurement (3.295 Seconds) of the timing relay was found outside Technical Specification and Acceptance Criteria (1.715 to 1.785 seconds) per procedure.
3/10/17: Electrician notification and discussion with Unit 1 Control Room Supervisor. Direction given to continue in accordance with procedure and make adjustments to within band (acceptance criteria).
3/10/17: Electricians retest of timing relay was performed. (Retest 1: 1.902 seconds, retest 2-9:
1.766 seconds). No adjustment was made. No issues identified with test equipment.
3/10/17: Electricians discussion with Electrical Maintenance Supervisor. Direction given to continue with test and document findings in Condition Report.
3/10/17: Electrician requested Control Room staff to log surveillance as Satisfactory. Discussion held on steps performed. All involved were aware that no adjustment was made.
Page 7 of 7 (04-2017)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 3/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 3. LER NUMBER South Texas Unit 1 05000-498 YEAR SEQUENTIAL NUMBER REV NO.
2017
- - 001
- - 00 3/10/17 1202: Unit 1 E1B Undervoltage Channel 4, including relay, declared Operable.
3/10/17: Condition Report 17-12616 documented conditions as identified during test.
3/13/17 1045: Technical Specification 3.3.2, Action 20A, time exceeded.
3/14/17: Review of Condition Report performed by STP Engineering (CR Action 17-12616-1), and recommendation made to the Control Room to declare E1B Undervoltage Channel 4 inoperable.
3/14/17 1500: Shift manager concurrence with engineering recommendation, relay declared inoperable, and Technical Specification 3.3.2, Action 20A, entered 3/15/17 0246: Relay replaced, Surveillance Test re-preformed, and E1B Undervoltage Channel 4 declared Operable.