05000341/LER-2020-001, Secondary Containment Inoperable Due to Both Airlock Doors Open
| ML20114E190 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 04/22/2020 |
| From: | Peter Dietrich DTE Electric Company |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC-20-0023 LER 2020-001-00 | |
| Download: ML20114E190 (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)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i) 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)(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)(vii), Common Cause Inoperability 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) |
| 3412020001R00 - NRC Website | |
text
April 22, 2020 NRC-20-0023 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. 2020-001 Peter Dietrich Senior Vice President and Chief Nuclear Officer DTE Energy Company 6400 N. Dixie Highway, Newport, Ml 48166 Tel: 734.586.4153 Fax: 734.586.1431 Ema il: pcter.clictrich@cltcencrgy.com DTE 10 CFR 50.73 Pursuant to 10 CFR 50.73(a)(2)(v)(C), DTE Electric Company (DTE) is submitting LER No.
2020-001, Secondary Containment Inoperable Due to Both Airlock Doors Open.
No new commitments are being made in this submittal.
Should you have any questions or require additional information, please contact Ms. Margaret (Peg) M. Offerle, Manager - Nuclear Licensing, at (734) 586-5076.
Sincerely, Peter Dietrich Senior Vice President and Chief Nuclear Officer Enclosure: Licensee Event Report No. 2020-001, Secondary Containment Inoperable Due to Both Airlock Doors Open cc:
NRC Project Manager NRC Resident Office Regional Administrator, Region III
Enclosure to NRC-20-0023 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Licensee Event Report (LER) No. 2020-001 Secondary Containment Inoperable Due to Both Airlock Doors Open
NRC FORM 366 (04-2020)
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://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 04/30/2020
NRC FORM 366 (04-2020) 05000
- 3. Page 1
OF
- 4. Title
- 5. Event Date Month Day Year
- 6. LER Number Year Sequential Number Rev No.
- 7. Report Date Month Day Year
- 8. Other Facilities Involved Facility Name Docket Number 05000 Facility Name Docket Number 05000
- 9. Operating Mode
- 10. Power Level
- 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)(2)(ii) 20.2203(a)(2)(iii) 20.2203(a)(2)(iv) 20.2203(a)(2)(v) 20.2203(a)(2)(vi) 20.2203(a)(3)(i) 20.2203(a)(3)(ii) 20.2203(a)(4) 50.36(c)(1)(i)(A) 50.36(c)(1)(ii)(A) 50.36(c)(2) 50.46(a)(3)(ii) 50.73(a)(2)(i)(A) 50.73(a)(2)(i)(B) 50.73(a)(2)(i)(C) 50.73(a)(2)(ii)(A) 50.73(a)(2)(ii)(B) 50.73(a)(2)(iii) 50.73(a)(2)(iv)(A) 50.73(a)(2)(v)(A) 50.73(a)(2)(v)(B) 50.73(a)(2)(v)(C) 50.73(a)(2)(v)(D) 50.73(a)(2)(vii) 50.73(a)(2)(viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)(ix)(A) 50.73(a)(2)(x) 73.71(a)(4) 73.71(a)(5) 73.77(a)(1) 73.77(a)(2)(i) 73.77(a)(2)(ii)
Other (Specify in Abstract below or in Page of 05000-
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
have occurred when both personnel access doors were open for entry/exit, the brief time required to close one of the doors (i.e., three seconds) was very small compared to the 17 minutes assumed in the analysis for reducing the post-accident secondary containment pressure to 0.25 inch of vacuum water gauge, and would not result in an increase in any onsite or offsite dose.
CAUSE OF THE EVENT
It was initially presumed that the cause of the event was the failure of the interlock ((IEL)), which is intended to prevent both doors from being open at the same time. However, subsequent testing confirmed that the interlock was functioning as designed to prevent opening of one door when the other door is open. The interlock is not designed to prevent a truly simultaneous opening of both doors. Therefore, the only cause was determined to be the brief, inadvertent, simultaneous opening of both inner and outer personnel access doors during normal entry and exit conditions.
CORRECTIVE ACTIONS
The immediate corrective action was to close at least one of the airlock doors to meet the SR 3.6.4.1.3 requirements and restore SC operability. Immediate actions were also taken to restrict access to the affected doors to prevent a recurrence of the condition while investigating the cause. It was subsequently confirmed that the interlock and doors were functioning as designed and access restriction was no longer required.
As indicated above, there are no safety concerns or consequences associated with the brief, inadvertent, simultaneous opening of both an inner and outer personnel access door during normal entry and exit conditions, and their prompt closure by normal means. No further corrective actions were required.
PREVIOUS OCCURRENCES
Events involving loss of SC due to both airlock doors being open at the same time have been reported in past, including the following recent LERs:
LER 2019-002 involved the loss of SC function due to both doors being opened at the same time as a result of a human performance error and a failure of the interlock.
LER 2019-003 involved the loss of SC function due to both doors being opened at the same time as a result of a human performance error.
The referenced occurrences above involved actual interlock failure, human performance errors, and/or different doors.
There is not a similar underlying concern or reason to this event, such as the same root cause, failure, or sequence of events. The corrective actions taken in response to the prior LERs could not have prevented the occurrence of the event in this LER.
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