05000440/LER-2018-001, Regarding Loss of Safety Function and Violation of Technical Specifications Due to Diode Failure
| ML18088A060 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 03/28/2018 |
| From: | Hamilton D FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-18-100 LER 2018-001-00 | |
| Download: ML18088A060 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 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)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 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)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 4402018001R00 - NRC Website | |
text
FENOC FirstEnergy Nuclear Operating Company Perry Nuclear Power Plant P.O. Box97 10 Center Road
- Perry, Ohio 44081 David B. Hamilton 440-280-5382 Vice President March 28, 2018 L-18-100 10CFR50.73(a)(2)(v)(D) 10CFR50.73(a)(2)(i)(B)
ATTN:
Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
Perry Nuclear Power Plant Docket No. 50-440, License No. NPF-58 Licensee Event Report Submittal Enclosed is Licensee Event Report (LER) 2018-001, "Loss of Safety Function and Violation of Technical Specifications due to diode failure".
There are no regulatory commitments contained in this submittal.
If there are any questions or if additional information is required, please contact Mr. Nicola Conicella, Manager - Regulatory Compliance, at (440) 280-5415.
Sinpetiely, David B. Hamilton Vice President
Enclosure:
LER 2018-001 cc:
NRC Project Manager NRC Resident Inspector NRC Region III Regional Administrator
Enclosure L-18-100 LER 2018-001
NRC FORM 366 (04-2017)
U.S. NUCLEAR REGULATORY COMMISSION 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.7/www.nrc.qov/readinq-rm/doc-collections/nureqs/staff/sr1022/r3/
APPROVED BY OMB:
NO. 3150-0104 EXPIRES:
3/31/2020 Estimated burden per response to comply with this mandatory 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 Information Services Branch (T-2 F43), U.S.
Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects.
Resource@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 an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME Perrv Nuclear Power Plant
- 2. DOCKET NUMBER 05000-440
- 3. PAGE 1
OF
- 4. TITLE:
Loss of Safety Function and Violation of Technical Specifications due to diode failure
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.
MONTH DAY FACILITY NAME YEAR DOCKET NUMBER 05000 11 06 2016 2018 001 00 28 2018 FACILITY NAME DOCKET NUMBER 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §:
(Check all that apply) 20.2201 (b) 20.2201 (d) 20.2203(a)(1) 20.2203(a)(2)(i) 20.2203(a)(3)(i) 20.2203(a)(3)(ii) 20.2203(a)(4) 50.36(c)(1)(i)(A) 50.73(a)(2)(ii)(A) 50.73(a)(2)(ii)(B) 50.73(a)(2)(iii)
D 50.73(a)(2)(iv)(A) 50.73(a)(2)(viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)(ix)(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)
D73.77(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) itLs-'
. V
-- "J 50.73(a)(2)(i)(C)
OTHER Specify in Abstract below or in
CAUSE
Two root causes were identified for the diode failure impact on the Division 2 DG start circuitry.
Based on failure analysis, it was concluded that the failure in November 2016 was the result of a diode manufacturing defect.
The second root cause was that a potential failure mechanism was introduced without specifically considering the effects of a shorted diode on the control circuitry of the diesel generator.
It was later determined that the diodes were enhancements to the circuit, but not required.
EVENT ANALYSIS
A Probabilistic Risk Assessment (PRA) evaluation of this event from the internal events model perspective indicated a delta core damage frequency (CDF) of 7.8E-06/yr and a delta large early release frequency (LERF) of 1.4E-07/yr or a significance level greater than very small when comparing to the Regulatory Guide 1.174 acceptance thresholds of 1.0E-06/yr and 1.0E-07/yr, respectively.
Discussions with the Region III Senior Risk Analyst (SRA), including qualitative assessments perspectives on external events including fire and seismic risk, ultimately concluded similar results based on implementation of the Significance Determination Process (SDP).
Applying this process, a final significance of low to moderate safety significance based on the delta core damage frequency (estimated to be 8.8e-06/yr by the SRA) being within the range of greater than 1.OE-06/yr and less than 1.OE-05/yr was determined.
Since the large early release frequency (LERF) contribution to the overall significance was no greater than the CDF estimate, CDF was determined to be the appropriate metric to be used for this conclusion.
CORRECTIVE ACTIONS
Corrective actions included removal of the subject diodes from both Division 1 and 2 DG control power circuit and a review of past design changes to verify failure modes have been considered for any new components.
PREVIOUS SIMILAR EVENTS
On May 6, 2016, Operations attempted to start the Division 2 Emergency Diesel Generator for performance of a post maintenance test (PMT) when unexpected alarms and abnormal indications were received.
A shorted diode was identified which caused a loss of power to the Division 2 DG controls.
The diode was replaced, no grounds were identified (no other diode failures) on the common portion of the control system, and the Division 2 DG subsequently passed the PMT.
The corrective actions for the May 2016 event were focused on eliminating only the failed diode in both the Division 1 and 2 DGs.
The apparent cause conclusions were subsequently refuted by laboratory testing performed for the November 6, 2016 event and the investigation was superseded.
This was subsequently addressed in the root cause report.
COMMITMENTS
None(06-2016)