ML23248A213

Response to Request for Additional Information Regarding Proposed License Amendment Request to Revise the Applicability Term for Reactor Coolant System Heatup and Cooldown Pressure-Temperature.

ML23248A213
Person / Time
Site:	Millstone
Issue date:	08/30/2023
From:	Lawrence D Dominion Energy Nuclear Connecticut
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
22-361B
Download: ML23248A213 (1)

Text

Dominion En e rgy Nu c lea r Connect ic ut, Inc.

5000 Dom in ion Bo ul evar d, Glen Alle n. VA 23 060 Dominion Energy.com August 30, 2023

U. S. Nuclear Regulatory Commission Serial No.22-361 B Attention: Document Control Desk NRA/SS: RO Washington, DC 20555 Docket No. 50-423 License No. NPF-49

DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED LICENSE AMENDMENT REQUEST TO REVISE THE APPLICABILITY TERM FOR REACTOR COOLANT SYSTEM HEATUP AND COOLDOWN PRESSURE TEMPERATURE LIMITATIONS FIGURES

By letter dated January 13, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23013A224), Dominion Energy Nuclear Connecticut, Inc. (DENC) submitted a license amendment request (LAR) to revise the Technical Specifications (TS) for Millstone Power Station Unit 3 (MPS3). The proposed change would revise MPS3 TS 3.4.9.1, "Reactor Coolant System Pressure/Temperature Limits,"

to reflect that Figures 3.4-2 and 3.4-3 (Heatup and Cooldown Limitations, respectively) would be applicable up to 54 effective full power years (EFPY).

In an email dated June 29, 2023, the NRC issued a draft request for additional information (RAI) related to the proposed LAR. On July 18, 2023, the NRC staff conducted a conference call with DENC staff to clarify the request. In an email dated July 18, 2023, the NRC transmitted the final version of the RAI (ADAMS Accession No. ML23199A283).

DENC agreed to respond to the RAI within 45 days of issuance, or no later than September 1, 2023.

provides DENC's response to the RAI. Attachment 2 provides a Figure and Tables which support DENC's responses to the RAI questions.

Serial No.22-361 B Docket No. 50-423 Page 2 of 3

If you have any questions or require additional information, please contact Mr. Shayan Sinha at (804) 273-4687.

Sincerely,

f Douglas rence Senior V resident - Nuclear Operations and Fleet Performance

COMMONWEAL TH OF VIRGINIA

COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Douglas C. Lawrence who is Senior Vice President - Nuclear Operations and Fleet Performance of Dominion Energy Nuclear Connecticut, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document on behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this 3D4"'day of ~YeY~-\\- I 2023.

My Commission Expires: °JO\\'\\\\ACAY\\.l '3\\ 1 2C2LJ

Kathryn Hill Barret Notary Public ~~- ]J.:-1f3P7\\U[

Commonwealth of Virginia Notary Public Reg.No. 7905256 My Commission Expires January 31, 2024 Attachments:

1. Response to Request for Additional Information Regarding Proposed License Amendment Request to Revise the Applicability Term for Reactor Coolant System Heatup and Cooldown Pressure-Temperature Limitations Figures

2. Figure and Tables to Support Responses to Request for Additional Information

Commitments made in this letter: None Serial No.22-361 B Docket No. 50-423 Page 3 of 3

cc: U.S. Nuclear Regulatory Commission Region I 475 Allendale Road, Suite 105 King of Prussia, PA 19406-1415

Richard V. Guzman Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 9 E3 11555 Rockville Pike Rockville, MD 20852-2738

NRC Senior Resident Inspector Millstone Power Station

Director, Radiation Division Department of Energy and Environmental Protection 79 Elm Street Hartford, CT 06106-5127 Serial No. 22-361B Docket No. 50-423

Attachment 1

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED LICENSE AMENDMENT REQUEST TO REVISE THE APPLICABILITY TERM FOR REACTOR COOLANT SYSTEM HEATUP AND COOLDOWN PRESSURE-TEMPERATURE LIMITATIONS FIGURES

Dominion Energy Nuclear Connecticut, Inc.

Millstone Power Station Unit 3 Serial No. 22-361B Docket No. 50-423 Attachment 1, Page 1 of 4

By letter dated January 13, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23013A224), Dominion Energy Nuclear Connecticut, Inc. (DENC) submitted a license amendment request (LAR) to revise the Technical Specifications (TS) for Millstone Power Station Unit 3 (MPS3). The proposed change would revise MPS3 TS 3.4.9.1, Reactor Coolant System Pressure/Temperature Limits, to reflect that Figures 3.4-2 and 3.4-3 (Heatup and Cooldown Limitations, respectively) would be applicable up to 54 effective full power years (EFPY).

In an email dated June 29, 2023, the NRC issued a draft request for additional information (RAI) related to the proposed LAR. On July 18, 2023, the NRC staff conducted a conference call with DENC staff to clarify the request. In an email dated July 18, 2023, the NRC transmitted the final version of the RAI (ADAMS Accession No. ML23199A283).

DENC agreed to respond to the RAI within 45 days of issuance, or no later than September 1, 2023.

This attachment provides DENCs response to the RAI.

RAI 1

Table 2 in Attachment 3, Evaluation of Adjusted Reference Temperatures and Reference Temperature Shifts, of the LAR presents Docketed Beltline Chemistries and Initial RTNDT Values from Millstone LRA, and identifies the initial RTNDT value for intermediate shell plate B9805-1 as 80.0°F. However, in Tables 1, 6, 7 and 8 of Attachment 3, as well as Table 4.2-2 of the Millstone Unit 3 License Renewal Application (ML040260103), the initial RTNDT value for intermediate shell plate B9805-1 is shown as 60.0°F. Identify the correct initial RTNDT value for intermediate shell plate B9805-1. Explain the basis for this discrepancy.

DENC Response to RAI-1

DENC has reviewed Table 2 in Attachment 3 to the LAR submittal and has confirmed that the correct initial RTNDT value for intermediate shell plate B9805-1 is 60.0°F. The basis for the discrepancy was a resolution/clarity issue in the electronic file for the LAR submittal. A clarified version of this table from the LA R is provided as Table 2 in to this RAI response letter.

RAI 2

Figure 5, Millstone Unit 3 RPV Rollout Map, in Attachment 3 of the LAR identifies th e MPS3 reactor pressure vessel (RPV) shell plates. The nozzle shell plates are identified as Plates B9404-1, B9404-2, and B9404-3. By letter dated November 19, 2020 (ML20324A703), DENC requested a Measurement Uncertainty Recapture Power Uprate.

Table IV-2, Calculated Neutron Fluence Projections of RV Beltline and Extended Beltline Materials for MPS3 at 54 and 60 EFPY, in that document identifies the Nozzle Shell Plates as B9804-1, B9804-2, and B9804-3. Provide confirmation of the plate identifications for RPV Nozzle Shell Plates in MPS3.

Serial No. 22-361B Docket No. 50-423 Attachment 1, Page 2 of 4

DENC Response to RAI-2

DENC has reviewed Figure 5 in Attachment 3 to the LAR submittal and has confirmed that the correct identifiers for the MPS3 RPV Nozzle Shell Plates are B9804-1, B9804-2, and B9804-3. A corrected version of this figure from the LAR Attachment 3, Figure 5 is provided as Figure 5 in Attachment 2 to this RAI response letter.

RAI 3

On October 14, 2014, the NRC issued Regulatory Issue Summary (RIS) 2014-11, Information on Licensing Applications for Fracture Toughness Requirements for Ferritic Reactor Coolant Pressure Boundary Components, (ML14149A165) whic h clarified that the beltline definition in 10 CFR 50, Appendix G is applicable to all RPV ferritic materials with projected neutron fluence values greater than 1x1017 neutrons/centimeter-squared (n/cm2) with energy greater than one million electron volts (E > 1 MeV), and this neutron fluence threshold remains applicable for the licensed operating period.

As noted in section 3.4 of Attachment 3, RPV nozzles with projected neutron fluence values less than the 4.28 x 1017 n/cm2 threshold defined in PWROG-15109-NP-A do not require further evaluation. Table 4 in Attachment 3 presents projected neutron fluence values at 54 and 60 EFPY for all beltline RPV materials. However, all beltline materials have not been included in Tables 1, 2, 5, 6, 7 and 8 in Attachment 3.

Describe how the P-T limit curves for MPS3 consider all ferritic pressure boundary components of the reactor vessel that are predicted to experience a neutron fluence exposure greater than 1x1017 n/cm2 (E > 1 MeV) at the end of the licensed operating period. If the current P-T limit curves do not consider all applicable ferritic pressure boundary components of the RPV that are predicted to experience a neutron fluence exposure greater than 1x1017 n/cm2 (E > 1 MeV) at the end of the licensed operating period, provide appropriately revised P-T limit curves for review. Provide all inputs and projected values for each beltline material. Similarly, for RTPTS, provide all inputs and projected values for each beltline material.

DENC Response to RAI-3

The P-T limit curves for MPS3 consider all ferritic pressure boundary components of the RPV that are predicted to experience a neutron fluence exposure greater than 1x1017 n/cm2 (E > 1 MeV) at the end of the licensed operating period of 54 EFPY (also referred to as in-scope RPV ferritic pressure boundary materials). Specifically, the current TS P-T limits were developed using bounding 32 EFPY 1/4T Adjusted Reference Temperature (ART) and 3/4T ART values of 124.8 °F and 107.0 °F, respectively, and were associated with RPV intermediate shell plate B9805-1. The bounding 54 EFPY 1/4T and 3/4T ART values are 118.7 °F and 107.0 °F and are associated with RPV lower shell plate B9820-

2. On this basis, the existing TS P-T limit curves are concluded to be valid to 54 EFPY.

The inputs and projected values for each beltline material predicted to experience a neutron fluence exposure greater than 1x1017 n/cm2 (E > 1 MeV) at the end of the licensed Serial No. 22-361B Docket No. 50-423 Attachment 1, Page 3 of 4

operating period (54 EFPY) are presented in Tables 7, 8, 10, and 11 in Attachment 2 to this RAI response letter.

Similar to the ART data, the inputs and projected values for the RTPTS values for all the in-scope RPV ferritic pressure boundary materials are included in the Tables 9 and 12 in to this RAI response letter.

RAI 4

As required by 10 CFR 50.61, To verify that RTNDT for each vessel beltline material is a bounding value for the specific reactor vessel, licensees shall consider plant-specific information that could affect the level of embrittlement. This information includes but is not limited to the reactor vessel operating temperature and any related surveillance program results.

The licensee stated the MPS3 surveillance weld material (heat 4P6052) is additionally represented in surveillance capsules at Seabrook and at a non-U.S. plant. The test results and information for the Seabrook reactor vessel material surveillance program are publicly available, including:

Yankee Atomic Electric Company, Analysis of Seabrook Station Unit 1 Reactor Vessel Surveillance Capsule U, June 26, 1992 (ML20099J203)

Duke Engineering and Services, Report No. DES-NFOA-98-01 Analysis of Seabrook Stations Unit 1, Reactor Vessel Surveillance Capsules U & Y, May 5, 1998 (ML20248L409)

WCAP-16526-NP, Rev. 0, Analysis of Capsule V from FPL Energy - Seabrook Unit 1 Reactor Vessel Radiation Surveillance Program, March 31, 2006 (ML061030088)

WCAP-18607-NP, Analysis of Capsule X from the NextEra Energy Seabrook Unit 1 Reactor Vessel Radiation Surveillance Program, September 30, 2021 (ML21277A388)

Provide the results of an evaluation of the applicability, including credibility, of the surveillance program results pertaining to weld heat 4P6052. Describe how these results were taken into consideration in evaluating the RTNDT of weld heat 4P6052 at MPS3.

DENC Response to RAI-4

The Seabrook Unit 1 surveillance capsule program results for the shared weld material heat 4P6052 have been evaluated and determined to be applicable to the evaluation of MPS3 weld heat 4P6052. Availability of the surveillance capsule data for weld material heat 4P6052 at the non-U.S. plant (Ascó Unit 2) was also investigated, but the data was found to be proprietary and unavailable for use.

The combined surveillance data from the Seabrook Unit 1 surveillance capsule program documented in WCAP-18607-NP and the MPS3 surveillance capsule program Serial No. 22-361B Docket No. 50-423 Attachment 1, Page 4 of 4

documented in WCAP-16629-NP were determined to be credible. Referring to Table 4 in to this RAI response letter, the unadjusted values for RTNDT (shown in paratheses) for MPS3 and for Seabrook 1 were adjusted based on considerations from Generic Letter (GL) 92-01, Reactor Vessel Structural Integrity. Specifically, the values were adjusted based on an Irradiation Temperature difference from MPS3 (558°F) and Seabrook 1 (559°F) and by the ratio of the chemistry factor of the vessel weld (30.7°F) to the chemistry factor of the surveillance weld (28.9°F for MPS3 and 30.7°F for Seabrook 1). Negative values of RTNDT were set to zero. The MPS3 and Seabrook Unit 1 surveillance weld data were used to develop a fitted Chemistry Factor (CF) value and RTNDT trend curve for weld heat number 4P6052, and the RTNDT data points of weld heat 4P6052 fell within the 28°F scatter band specified in Regulatory Guide (RG) 1.99, Radiation Embrittlement of Reactor Vessel Materials, Revision 2 for surveillance weld materials. Therefore, the surveillance data for weld heat number 4P6052 are deemed credible.

DENC concludes that the limiting plate material RTNDT and RTPTS for MPS3 (B9820-2) bound the RTNDT and RTPTS of weld material 4P6052 considering either position 1.1 or position 2.1 of RG 1.99, Revision 2. The results which support this conclusion are shown in Tables 7, 8, and 9 of Attachment 2 to this RAI response letter.

Serial No. 22-361B Docket No. 50-423

Attachment 2

FIGURE AND TABLES TO SUPPORT RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION

Dominion Energy Nuclear Connecticut, Inc.

Millstone Power Station Unit 3 Serial No. 22-361B Docket No. 50-423 Attachment 2, Page 1 of 8

Note: The Reference numbers in table/figure footnotes correlate to the Reference numbers in LAR Attachment 3, with the exception of new Reference [22].

Table 2: Docketed Beltline Chemistries and Initial RTNDT Values from Millstone LRA Ta ble 4.2-2 Millstone Unit 3

• RT PTS Values at 54 EFPY

Chemi c al Ma teria l De sc ription Compo sition In itial C h emis try Inner Mar gin t.RTPTs R Tprs

Re a c to r RT NDT Fac to r Su rfac e *F *F *F Ve sse l *F *F F luence m 2 Beltline Ma tl. Hea t Ty p e Cu Ni E19 n / c R egio n ldent. Number Wt. % W t.%

L o ca tio n

Intermed iate B9805 -1 C4039-2 SA-533 B 0.0 5 0.64 60.0 1 31.02 3.31 34.0 40.7 134. 7 She ll C l. 1

Intermed iate B9805 -2 C4068-1 SA-533B 0.05 0.64 6.2 1 31.02 3.31 34.0 40.7 80.9 She ll C l. 1

Intermed ia te B9805-3 C4028-1 SA-533B 0.05 0.65 -3.3 1 31.0 2 3.3 1 34.0 40.7 71.4 She ll C l. 1

Lo w er She ll B9 820 - 1 B8961 - 1 SA-533B 0.08 0.63 7.0 1 51.02 3.31 34.0 67.0 108. 0 C l. 1

Lo w er She ll B9820 -2 D1242-2 SA-533B 0.07 0.60 38.8 44.02 3.31 34.0 57.8 130.6 C l.1

Lower Sh ell B9820 -3 D 1242 - 1 SA-533 B 0.06 0.6 1 18.6 37.02 3.31 34.0 48.6 101.2 C l.1

A ll We lds 4P6052 Linde 0 09 1 0.05 0.05 -50.0 1 3 1.72 3.31 56.0 47.7 47.7

1. Measu re V alue

2. Regu la tory Guide 1.99, Re v ision 2, Pos itio n 1 Figure 5: Millstone Unit 3 RPV Rollout Map

0 Outlet hie! rile! Outlet OIAJel hie! Inlet Outlet

Plate 89804 -1 P la te 898 04 -2 Plate 89804 -3 40 103-121 (Heat No. 4P60521 80...... 'i 'i 'i Plate !!! Pla te !!! Plate !!! z 99805 -1 ! z 89805 - 2 ~ z 89805-3 ! ? ? ?

(Heat No. C4039-2)...... (Heat No. C4068*1)...... (Heat No. C4028 -1)..,,..,..

(/).. "D... "D.... "D.... n O>

w 120 0 0 0 J: _g; "' "' !::! !::!

(.) ------ ------------ ------------- *

~ 101-171 (Heat No. 4P6052)

....J 160 J: x %.... ;

i Plate ~ !!! !!! ~ ate ~ z Plate ! z B9820-3 ? B9820-1.!. ? B9820-2 ? ~ z Pl 200 (Heat No. B8961-1).... ~...... r;: "D (Heat No. 0 1242-2) "D ( Heat No. 01 242-1).... "D O>.,.. n..

0 ------- 0 - - - - - -* 0

- - - - *- _;-..,. _ - u,-- -!::! !::! - * -

240 257 0 90 180 270 360 AZIMUTHAL DEGREES Note :

( 1 ) P late iden tifiers we re co rrected to al ign with C MT R data [9]

Serial No. 22-361B Docket No. 50-423 Attachment 2, Page 2 of 8

Table 4: Surveillance Data for Surveillance Weld Heat #4P6052 for Calculation of Chemistry Factor

Plant Capsule Capsu le Fluence <1> (x 10 19 FF <2>.6.RT NDT (3) FF*.6.RT NDT FF2 n/cm 2, E > 1.0 MeV) ( OF) ( OF) u 0.400 0.746 32.5 24.2 0.557 (30.6 )

Millstone X 1.98 1. 186 0 0.0 1.407 3 (-6.3) w 3. 16 1.303 0 0.0 1.698 (-1.3) u 0.311 0.680 26.4 18.(25.4 ) 0 0.462 3 1.073 (24.25.3 Se abrook y 1.3 ) 27. 1 1. 151 1 V 2.66 1.262 42.7 53.9 1.593 (41. 7)

X 6.03 1.437 34.8 50.(33.8 ) 0 2.065 SUM : 173.2 8.932 CF 4P6052 = L ( FF *b.R T NDT ) + L ( F F 2) = (1 73.2 ) + (8.932 ) = 19.4°F Not es:

(1) M illsto n e 3 flu e nc es ta ke n fro m [12]. Sea brook 1 fluence s t a ke n from [22).

(2) FF= f 02&--0I O!oef.J)

(3) U n a djus ted v a lu es fo r LI.R T No r (shown in pa re nth e ses) w e re ta ke n fro m [12] for M illston e 3 a n d (22] fo r Sea broo k 1. V a lues w ere a djusted b ased on a n Irra dia tion T em pe ra ture d iffe re nce from M illstone 3 (558 °F ) a nd Sea brook 1 (55 9 °F) a nd the n w e re a djuste d b y the ratio o f the c he mistry facto r o f the vessel we ld (30. 7°F) to t he c he mistry fa c to r o f the su rve illa n ce w eld ( 28.9°F for M illsto n e 3 a n d 30.7° F for Sea brook 1). Nega tive v a lues o f LI. RT No r w ere set to zero.

New Reference [22]:

Westinghouse Report, WCAP-18607-NP, Revision 0, Analysis of Capsule X from the NextEra Energy Seabrook Unit 1 Reactor Vessel Radiation Surveillance Program, March 2021, SI File Number 1901402.204.