05000341/LER-2021-003, High Pressure Coolant Injection Inoperable Due to Contact Oxidation
| ML21363A084 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 12/29/2021 |
| From: | Peter Dietrich DTE Electric Company |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC-21-0056 LER 2021-003-00 | |
| Download: ML21363A084 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3412021003R00 - NRC Website | |
text
Peter Dietrich Senior Vice President and Chief Nuclear Officer DTE Electric Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.4153 Fax: 734.586.1431 Email: peter.dietrich@dteenergy.com December 29, 2021 10 CFR 50.73 NRC-21-0056 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Fermi 2 Power Plant NRC Docket No. 50-341 NRC License No. NPF-43
Subject:
Licensee Event Report (LER) No. 2021-003 Pursuant to 10 CFR 50.73(a)(2)(v)(D), DTE Electric Company (DTE) is submitting LER No.
2021-003, High Pressure Coolant Injection Inoperable due to Contact Oxidation.
No new commitments are being made in this submittal.
Should you have any questions or require additional information, please contact Mr. Ertman L Bennett III, Manager - Nuclear Licensing, at (734) 586-4273.
Sincerely, Peter Dietrich Senior Vice President and Chief Nuclear Officer Enclosure: Licensee Event Report No. 2021-003, High Pressure Coolant Injection Inoperable due to Contact Oxidation cc:
NRC Project Manager NRC Resident Office Regional Administrator, Region III
Enclosure to NRC-21-0056 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Licensee Event Report No. 2021-003 High Pressure Coolant Injection Inoperable due to Contact Oxidation
Abstract
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High Pressure Coolant Injection Inoperable due to Contact Oxidation 6
3 2021 2021 003 0
12 29 2021 N/A N/A 1
100 Ertman L Bennett III - Manager, Nuclear Licensing 734-586-4273 N/A N/A N/A N/A N/A On 6/3/2021 at 0313 a condition was encountered during performance of the HPCI Condensate Storage Tank Level Channel Functional Test when the HPCI Pump Suction Isolation Valve from the Suppression Pool was slow to open. The Channel Functional Test was successfully completed; however, the valve took approximately 5 minutes to open on the simulated low Condensate Storage Tank (CST) level signal. Technical Specification (TS) 3.3.5.1 Action D.2.1 and D.2.2 were entered on 6/3/2021 at 0241 (surveillance start) which allows 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to place the channel in trip or to align HPCI pump suction to the suppression pool. Troubleshooting of the condition identified an oxidated relay contact was the cause of the slow opening of the suction isolation valve. After relay repair and a repeat performance of the HPCI CST Level Channel Functional Test the Limiting Condition of Operation was exited on 6/4/2021 at 1451. It was later determined that the condition impacted both channels of the CST low level suction transfer logic, and during the condition TS 3.3.5.1 Action D.1 should have been entered resulting in declaring the HPCI system inoperable. HPCI suction was transferred to the suppression pool on 6/3/2021 at 1817 completing required actions for D.2.2 also making condition D.1 not applicable.Page of 05000-
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS
The HPCI system normally takes suction from the condensate storage tank. This tank is designed such that the last 150,000 gal is reserved for use by the HPCI or RCIC systems by the tanks standpipe design. HPCI suction automatically switches to the suppression pool upon low condensate storage tank (CST) level (equivalent to about 45,000 gallons of water in the CST). However, while the plant is operating, the CST is maintained at a normal level in excess of 400,000 gallons.
A Technical Evaluation determined if HPCI operation were required with the CST inventory at the low CST level suction transfer setpoint that HPCI would operate as designed for most of the approximate 5 minutes of the slow suction transfer condition. However, before suction transfer would have been completed the CST level would have lowered below the level where vortexing, or air entrainment would have occurred. Without operator action, HPCI would trip on a low suction pressure signal. Then upon completion of the suction transfer, suction pressure would be restored, and HPCI would automatically restart if demanded and continue to inject.
However, if HPCI operation were required with CST inventory at the low CST level suction transfer setpoint operators would receive a control room annunciator, HPCI/RCIC Suction Transfer CST Level Low. The associated alarm procedure directs the operator to verify the automatic transfer occurs as expected. If automatic suction transfer does not occur, operators are trained per station procedures to complete automatic actions manually. Therefore, the operator would have established the proper line-up. The relay contact associated with manual operation of the HPCI Pump Suction Isolation Valve [ISV] was unaffected.
During the event Division 2 Low Pressure Coolant Injection (LPCI) [BO], Core Spray (CS) [BM] and Automatic Depressurization System (ADS) were operable. Division 1 LPCI and CS were operable except during the Division 1 EECW pump and valve testing.
CAUSE OF THE EVENT
The direct cause is Electrical Contact Degradation due to the oxidation of the E41A-K17 relay contact.
CORRECTIVE ACTIONS
The initial performance of the channel test was completed successfully though the transfer was slow.
The E41A-K17 contact was burnished during initial troubleshooting. The valve was returned to operable after the contact burnishing and was successfully tested.
The Inspection and Testing of Multi-Contact Auxiliary Relays HFA, HMA and HGA procedure was revised to require contact burnishing.
This condition was entered into the corrective action program and lessons learned were determined and communicated.
PREVIOUS OCCURRENCES
There are no previous similar occurrences.
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