05000461/LER-2020-003, Reactor Core Isolation Cooling System Card Fuse Failure Results in a Condition Prohibited by Technical Specifications and That Could Have Prevented Fulfillment of a Safetv Function Needed to Control
| ML21159A106 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 02/22/2021 |
| From: | Chalmers T Exelon Generation Co LLC |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| U-604608 LER 2020-003-00 | |
| Download: ML21159A106 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 4612020003R00 - NRC Website | |
text
Clinton Power Station 8401 Power Road Clinton. IL 61727 U-604608 February 22, 2021 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461 Subject: Licensee Event Report 2020-003-00 Exelon Generation T.
10 CFR 50.73 SRRS 5A.108 Enclosed is Licensee Event Report (LER) 2020-003-00: Reactor Core Isolation Cooling System Card Fuse Failure Results in a Condition Prohibited by Technical Specifications and That Could Have Prevented Fulfillment of a Safety Function Needed to Control the Release of Radioactive Material. This report is being submitted in accordance with the requirements of 10 CFR 50. 73.
There are no regulatory commitments contained in this report.
Should you have any questions concerning this report, please contact Mr. Dale Shelton, Regulatory Assurance Manager, at (217) 937-2800.
Respectfully,
~
Thom**D.~r Site Vice President Clinton Power Station
Attachment:
Licensee Event Report 2020-003-00 cc:
Regional Administrator - Region Ill NRC Senior Resident Inspector - Clinton Power Station Office of Nuclear Facility Safety - Illinois Emergency Management Agency
Abstract
On 12/26/20, at 0205 CST, during performance of Reactor Core Isolation Cooling (RCIC) surveillance procedures, the Division 2 RCIC indication response was not as expected. Troubleshooting determined the indication response was due to failure of the Div. 2 RCIC-5 card, which provides an isolation signal. Technical Specification (TS) 3.3.6.1, Primary Containment and Drywell Isolation Instrumentation, was entered. Past operability review found that the condition existed from 12/21 /20, through 12/26/20, exceeding the TS 3.3.6.1, Action D.1, 24-hour action statement.
The Div. 2 RCIC-5 card failed due to an internal blown fuse. The cause of the missed opportunity to identify the failure on 12/21/20 was Operations did not properly recognize the risk associated with the condition and initiate timely actions to evaluate the impact on operability. The card was replaced and tested on 12/26/20, at 1506 CST. Refresher training will be conducted for appropriate Operations personnel regarding the need to perform manual self tests or use alternate indications when anomalous indications or alarms occur. This condition is reportable under 10 CFR
- 50. 73(a)(2)(i)(B) and 10 CFR 50. 73(a)(2)(v)(C). There was no impact to the health and safety of the public or plant personnel from this condition as the isolation safety function was maintained throughout the event. This event does not meet the criteria for a Safety System Functional Failure.
PLANT AND SYSTEM IDENTIFICATION
YEAR 2020 *
- 3. LER NUMBER SEQUENTIAL NUMBER 003 General Electric -- Boiling Water Reactor, 3473 Megawatts Thermal Rated Core Power Energy Industry Identification System (EllS) codes are identified in text as [XX].
EVENT IDENTIFICATION REV NO.
00 Reactor Core Isolation Cooling System Card Fuse Failure Results a Condition Prohibited by Technical Specifications and That Could Have Prevented Fulfillment of a Safety Function Needed to Control the Release of Radioactive Material A.
Plant Operating Conditions Before the Event
Unit: 1 Mode: 1 Event Date: December 26, 2020 Mode Name: Power Operation B.
Description of Event
Event Time: 0205 Reactor Power: 098 On December 26, 2020, at approximately 0205 CST, during performance of Reactor Core Isolation Cooling (RCIC) system [BN] steam line flow and supply pressure surveillance procedures 9030.01C034 and 9030.01C035, the Division 2 RCIC indication response was not as expected.
Technical Specification (TS) 3.3.6.1, Primary Containment and Drywell Isolation Instrumentation, Action D.1, place affected channel in trip within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, was entered. Troubleshooting determined the indication response was due to a failure of the Division 2 RCIC-5 card, D-A 14-A 112, which was not sending an isolation signal during the surveillance. The failed Division 2 RCIC-5 card was replaced and successfully tested on December 26, 2020, at 1506 CST and TS 3.3.6.1, Action D.1, was exited.
The failed Division 2 RCIC-5 card provides an isolation signal that automatically initiates closure of appropriate Primary Containment Isolation Valves (PCIVs) and drywell isolation valves.
A review for past operability found that the condition could have been identified during performance of procedure 9030.01C041, RCIC Turbine Exhaust Diaphragm Pressure, on December 21, 2020, at 1515 CST, when an alarm did not occur as expected. Although the alarm was not required in order to meet TS surveillance requirements based on the procedure acceptance criteria, further investigation determined the failure was an indication the Division 2 RCIC-5 card was not providing an output isolation signal. Therefore, there is firm evidence that the condition existed from December 21, 2020, through December 26, 2020, which exceeded the TS 3.3.6.1, Action D.1, 24-hour action statement.
NRC FORM 3E6A (08-2020)
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C.
Cause of the Event
SEQUENTIAL NUMBER 003 REV NO.
00 An analysis of the failed Division 2 RCIC-5 card, D-A 14-A 112, identified a blown fuse [FU] internal to the card.
The cause of the failure to identify the failed card on December 21, 2020, was Operations did not recognize the risk associated with the condition and did not initiate actions to evaluate the operability.
D.
Safety Consequences
The condition described in this LER is reportable under 10 CFR 50. 73(a)(2)(i)(B), any operation or condition which was prohibited by the plant's Technical Specifications. Because this condition affected one division of RCIC logic, the safety function to automatically initiate closure of appropriate PCIVs and drywell isolation valves was maintained and would have initiated if required. However, during performance of surveillance procedures 9030.01 C034 and 9030.01 C035 on December 26, 2020, the redundant automatic isolation capability was removed from service, creating a short duration loss of containment isolation function. This condition is reportable under 10 CFR 50.73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of the safety function of a system needed to control the release of radioactive material. Evaluation of the impact of this leakage pathway determined that the containment function would be met by Operations personnel using existing procedures to perform manual isolations if automatic isolations did not occur as expected, if an event had occurred. Therefore, there was no impact to the health and safety of the public or plant personnel from this condition. This event does not meet the criteria for a Safety System Functional Failure.
E.
Corrective Actions
The failed Division 2 RCIC-5 card was replaced and successfully tested on December 26, 2020, at 1506 CST.
Refresher training will be conducted for appropriate Operations personnel regarding the Nuclear System Protection System (NSPS) self-test system, how it is used to meet surveillance requirements, and the need to perform manual self tests or use alternate indications to verify channel operability when anomalous indications or alarms occur.
F.
Previous Similar Occurrences A review of previous LERs did not identify any events that were similar to the condition described in this LER.
G.
Component Failure Data
The Division 2 RCIC card that failed is a NSPS (Essential Logic) RCIC-5 made by GE. Page _ 3 _ of _ 3_