NRC-20-0043, Response to Confirmatory Action Letter EA-19-097 for Fermi 2 Regarding Containment Coatings and Completion of DTE Commitment
| ML20188A299 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 07/06/2020 |
| From: | Peter Dietrich DTE Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| EA-19-097, NRC-20-0043 | |
| Download: ML20188A299 (3) | |
Text
Peter Dietrich Senior Vice President and Chief Nuclear Officer DTE Energy Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.4153 Fax: 734.586.1431 Email: peter.dietrich@dteenergy.com July 6, 2020 NRC-20-0043 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:
Response to Confirmatory Action Letter EA-19-097 for Fermi 2 Regarding Containment Coatings and Completion of DTE Commitment In Reference 1, DTE Electric (DTE) made a commitment to mitigate the degraded coating in the submerged portion of the pressure suppression chamber, also referred to as the torus. The DTE commitment was subsequently confirmed by the NRC in the Confirmatory Action Letter (CAL)
EA-19-097 in Reference 2. DTE notified the NRC of changes in the commitment and clarifications in References 3 and 5. The NRC acknowledged the changes in commitment in References 4 and 6. The full text of the DTE commitment, including the changes, is as follows:
References:
- 1) DTE Letter to NRC, DTE Commitment Regarding Containment Coatings, NRC-19-0065, dated September 26, 2019 (ML19270E090)
- 2) NRC Letter to DTE, Confirmatory Action Letter - Fermi Power Plant, Unit 2 Commitment to Address Degraded Torus Coatings, EA-19-097, dated October 4, 2019 (ML19280D881)
- 3) DTE Letter to NRC, Change in DTE Commitment Regarding Containment Coatings and Additional Information, NRC-20-0019, dated March 13, 2020 (ML20073N414)
- 4) NRC Letter to DTE, Revision to Confirmatory Action Letter - Fermi Power Plant, Unit 2 Commitment to Address Degraded Torus Coatings, EA-19-097, dated March 27, 2020 (ML20087L769)
- 5) DTE Letter to NRC, Additional Changes in DTE Commitment Regarding Containment Coatings, NRC-20-0025, dated June 19, 2020 (ML20171A600)
- 6) NRC Letter to DTE, Revision to Confirmatory Action Letter - Fermi Power Plant, Unit 2 Commitment to Address Degraded Torus Coatings, EA-19-097, dated June 24, 2020 (ML20177A383)
USNRC NRC-20-0043 Page 2 DTE commits to mitigate the degraded coating in the submerged portion of the torus by removing all coating (i.e., to the extent possible) in the submerged portion of the torus and applying a qualified coating capable of withstanding design basis accident conditions. Removal of coating and application of qualified coating will also be performed for torus internals in the submerged portion of the torus with the exception of the internal surfaces of the downcomers and the internal surfaces of process piping. The internal surfaces of the submerged portion of the downcomers and the coated internal surfaces of the submerged portion of process piping will be inspected and degraded coating, if any, will be removed during the next refueling outage. Torus internals that do not require protective coating to perform their intended function may be left uncoated.
Following completion of these activities, unqualified coatings in the submerged portion of the torus will be explicitly addressed for potential impact on ECCS strainers in the same manner as other unqualified coatings in primary containment. This DTE commitment will be completed prior to resuming power operation following the next refueling outage. The next refueling outage will begin no later than April 30, 2020.
The purpose of this letter is to notify the NRC that the actions have now been completed in accordance with the DTE commitment and CAL. A summary of the significant activities performed by DTE is provided as follows.
All coating was removed from the torus shell and torus internal components to the extent possible, with the exception of the downcomer internal surfaces, below an elevation of approximately 5582. This elevation is approximately one foot above the normal water level in the torus including the Technical Specification (TS) allowable range (557+/-2).
The coating on the internal surfaces of all 80 downcomers was inspected from the bottom up to a few inches above the torus water level. No blistered coating was identified. In several of the downcomers, a few small areas of mechanical damage and corrosion were identified. These minor coating defects were removed as needed.
A review of design information associated with process piping in the submerged portion of the torus, and supplemental inspections during RF20, identified no process piping (other than the downcomers) that was internally coated.
A new design basis accident (DBA) qualified coating was applied up to the elevation of approximately 5582. The new coating was applied to the surfaces in this region except for the downcomer internal surfaces and those which were determined to not require a protective coating to perform their intended function, such as stainless steel surfaces.
A review was performed to document and quantify unqualified coating resulting from the above activities. The quantity of unqualified coating, although small, will be added to the unqualified coatings log for evaluation against available margin in ECCS strainer debris loading calculations in the same manner as other unqualified coatings in primary containment.
The Fermi 2 twentieth refueling outage (RF20) began on March 21, 2020. All the activities described above were completed prior to resuming power operation from RF20. Therefore, the commitment was completed according to the agreed upon schedule.
USNRC NRC-20-0043 Page 3 Should you have any questions or require additional information, please contact Ms. Margaret Offerle, Manager - Nuclear Licensing, at (734)586-5076.
cc: NRC Project Manager NRC Resident Office Peter Dietrich Senior Vice President and Chief Nuclear Officer Regional Administrator, Region III