RS-21-019, Response to Request for Additional Information Regarding Application for Revision to TS 5.5.9, Steam Generator (SG) Program, for a One-Time Deferral of Steam Generator Tube Inspections
| ML21040A281 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 02/09/2021 |
| From: | Demetrius Murray Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RS-21-019 | |
| Download: ML21040A281 (4) | |
Text
Exelon Generation RS-21-019 4300 Winfield Road Warrenville, IL 60555 630 657 2000 Office 10 CFR 50.90 February 9, 2021 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457
Subject:
Response to Request for Additional Information Regarding Application for Revision to TS 5.5.9, "Steam Generator (SG) Program,"
for a One-Time Deferral of Steam Generator Tube Inspections
References:
- 1) Letter from D. Murray (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Application for Revision to TS 5.5.9, 'Steam Generator (SG) Program,' for a One-Time Deferral of Steam Generator Tube Inspections," dated December 16, 2020 (ADAMS Package Accession No. ML20351A433).
- 2) Email from J. Wiebe (U.S. Nuclear Regulatory Commission) to P. A.
Henderson (Exelon Generation Company, LLC), "Request for Additional Information Regarding Braidwood, Unit 1, Amendment Request for One-time Deferral of Steam Generator Inspections," dated February 5, 2021.
By application dated December 16, 2020 (Reference 1 ), Exelon Generation Company, LLC (EGC) requested an amendment to the Technical Specifications (TS) for Renewed Facility License Nos. NPF-72 and NPF-77 for Braidwood Station, Units 1 and 2 (Braidwood). The proposed changes would allow a one-time deferral of the steam generator tube inspections required in Section 5.5.9.d.2, "Steam Generator (SG) Program," of the TS for Braidwood, Units 1 and 2. Although the proposed change only affects Braidwood Unit 1, Reference 1 and this submittal are docketed for Braidwood Station, Units 1 and 2, since the TS are common to Units 1 and 2 for Braidwood.
The proposed changes were submitted in response to social distancing recommendations by the United States Centers for Disease Control and Prevention, which have been issued as a defensive measure against the spread of the Coronavirus Disease 2019 (COVID-19).
February 9, 2021 U.S. Nuclear Regulatory Commission Page 2 In NRC email dated February 5, 2021 (Reference 2), the NRC determined that additional information is needed to complete its review. The Attachment to this letter provides the requested information.
EGC has reviewed the information supporting the No Significant Hazards Consideration and the Environmental Consideration that was previously provided to the NRC in Attachment 1 of the Reference 1 letter. The additional information provided in this submittal does not affect the conclusion that the proposed license amendment does not involve a significant hazards consideration. This additional information also does not affect the conclusion that there is no need for an environmental assessment to be prepared in support of the proposed amendment.
In accordance with 10 CFR 50.91, "Notice for public comment; State consultation," paragraph (b),
EGC is providing a copy of this letter and its attachment to the State of Illinois.
This letter contains no regulatory commitments. Should you have any questions concerning this submittal, please contact Mr. Phillip A. Henderson at (630) 657-4727.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 9th day of February 2021.
Dwi Murray Sr. Manager - Licensing Exelon Generation Company, LLC
Attachment:
Response to Request for Additional Information cc:
NRC Regional Administrator, Region Ill NRC Senior Resident Inspector - Braidwood Station Illinois Emergency Management Agency - Division of Nuclear Safety
ATTACHMENT Response to Request for Additional Information By application dated December 16, 2020 (Reference 1 ), Exelon Generation Company, LLC (EGC) requested an amendment to the Technical Specifications (TS) for Renewed Facility License Nos. NPF-72 and NPF-77 for Braidwood Station, Units 1 and 2 (Braidwood). This proposed amendment request would modify Technical Specifications (TS) 5.5.9, "Steam Generator (SG) Program," for a one-time revision to the frequency for SG tube inspections. The requested TS amendments support deferral of the TS required inspections until the next Unit 1 refueling outage.
By email dated February 5, 2021 (Reference 2), the NRC determined that additional information is needed to complete its review. This attachment provides the requested information.
References:
- 1)
Letter from D. Murray (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Application for Revision to TS 5.5.9, 'Steam Generator (SG) Program,'
for a One-Time Deferral of Steam Generator Tube Inspections," dated December 16, 2020
- 2)
Email from J. Wiebe (U.S. Nuclear Regulatory Commission) to P. A Henderson (Exelon Generation Company, LLC), "Request for Additional Information Regarding Braidwood, Unit 1, Amendment Request for One-time Deferral of Steam Generator Inspections,"
dated February 5, 2021 NRC RAI 1 In Table 2 of Attachment 1 of the "RS-20-154, Application for Revision to TS 5.5.9, Steam Generator (SG) Program for a One-Time Deferral of [[system" contains a listed "[" character as part of the property label and has therefore been classified as invalid. Tube Inspections|December 16, 2020, letter]] the column entitled "Preventative Due to FO [foreign object]" totals 59, however, the table states the total is 55. Clarify the total number of tubes that have been preventatively plugged due to foreign objects (FOs).
EGC Response to NRC RAI 1 In Reference 1, Table 2, "Braidwood Unit 1 Plugging History by Degradation Mechanism," of, "Description and Assessment," contains a typographical error where it stated that the total number of tubes that have been preventatively plugged due to foreign objects (FOs) for the column entitled "Preventative Due to FO" is 55. The corrected total number of tubes that have been preventatively plugged due to FOs is 59.
NRC RAI 2 In the "RS-20-154, Application for Revision to TS 5.5.9, Steam Generator (SG) Program for a One-Time Deferral of [[system" contains a listed "[" character as part of the property label and has therefore been classified as invalid. Tube Inspections|December 16, 2020, letter]] the first sentence of the third paragraph in Attachment 1, Section 4.1.2, "Lattice Grid Support Wear," states "[f]or the QA [Operational Assessment], a conservative growth rate must be assumed for fan bar wear going forward. A growth rate of 2.0% TW [through wall]/EFPY [effective full power years] is assumed.... " Clarify whether the "fan bar wear" or the "lattice grid support wear" is 2.0 percent TW/EFPY.
EGC Response to NRC RAI 2 In Reference 1, Attachment 4, "Framatome Inc. Document No. 51-9320766-000, 'Braidwood 1 Steam Generator Operational Assessment Deferral of the Spring 2021 Steam Generator Inspections,"' Section 4.1.2, "Lattice Grid Support Wear," contains typographical errors Page 1 of 2
ATTACHMENT Response to Request for Additional Information regarding the use of "fan bar wear." The same conservative bounding growth rate of 2.0%
TW/EFPY was applied to structural support wear at both fan bar and lattice grid locations.
Therefore, the corrected statements in Reference 1, Attachment 4, Section 4.1.2 for the use of "lattice grid support wear" are as follows for the second and third paragraphs, respectively:
"... The adjustment was performed as follows:
BOC20 UBD = upper 95%/50% maximum depth of in-service lattice grid support wear at the beginning of Cycle 20.... "
"For the OA, a conservative growth rate must be assumed for lattice grid support wear going forward... "
Note that these changes do not alter any of the calculations or predicted margin for lattice grid support wear at the End of Cycle 23.
NRC RAI 3 In the "RS-20-154, Application for Revision to TS 5.5.9, Steam Generator (SG) Program for a One-Time Deferral of [[system" contains a listed "[" character as part of the property label and has therefore been classified as invalid. Tube Inspections|December 16, 2020, letter]] the last sentence of the fourth paragraph in Section 4.1.3 states that "[t]he deepest predicted EOC23 [end of cycle 23] wear (24.9% TW) is not expected to exceed the conservative structural limit (57.6% TW) for an axial flaw with limited circumferential extent and an assumed length of 2.0 inches." However, Table 4-1 notes the maximum predicted depth at the EOC23 for two FOs left in service in SG 1 C is 25.9% TW. Clarify the deepest predicted EOC23 FO wear.
EGC Response to NRC RAI 3 In Reference 1, Attachment 4, Section 4.1.3, "Foreign Object Wear," Table 4-1, "Priority 3 Foreign Objects Left in Service at A1R19," stated the correct maximum predicted depth at the EOC23 for two FOs left in service in SG 1 C, which is 25.9% TW. Therefore, the following is the corrected statement for the last sentence of the fourth paragraph in Reference 1, Attachment 4, Section 4.1.3:
"The deepest predicted EOC23 wear (25.9% TW) is not expected to exceed the conservative structural limit (57.6% TW) for an axial flaw with limited circumferential extent and an assumed length of 2.0 inches."
Note that this 1 % TW change does not alter any calculations and that the deepest predicted 25.9% TW wear indications from foreign objects still have significant margin to not exceed the conservative structural limit (57.6% TW) for an axial flaw with limited circumferential extent and an assumed length of 2.0 inches.
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