Text

Connecticut, Inc., Millstone Power Station Unit 2, Alternative Request RR-04-22 for Implementation of Extended Reactor Vessel Inservice Inspection Interval
	ML16057A179
Person / Time
Site:	Millstone
Issue date:	02/18/2016
From:	Mark D. Sartain; Dominion Nuclear Connecticut
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	RR-04-22
	Download: ML16057A179 (9)
	v • d • e

Dominion Nuclear Connecticut, Inc. *", hpm hhm~mm 5000 Dominion Boulevard, Glen Allen, VA 23060 -[ JD mno Web Address: www.dom.com February 18, 2016 U. S. Nuclear Regulatory Commission Serial No.16-036 Attention: Document Control Desk NLOSIWDC R0 Washington, DC 20555 Docket No. 50-336 License No. DPR-65 DOMINION NUCLEAR CONNECTICUT. INC.

MILLSTONE POWER STATION UNIT 2 ALTERNATIVE REQUEST RR-04-22 FOR IMPLEMENTATION OF EXTENDED REACTOR VESSEL INSERVICE INSPECTION INTERVAL Pursuant to 10 CFR 50.55a(z)(1), Dominion Nuclear Connecticut, Inc. (DNC) requests an alternative to the requirement of the American Society of Mechanical Engineers (ASME)

Code, Section Xl, Paragraph IWB-2412, Inspection Program B, for Millstone Power Station Unit 2 (MPS2) which requires examination of identified reactor vessel pressure-retaining welds (Examination Category B-A and B-D) once each 10-year interval. The proposed alternative would extend the current examination frequency from 10 years to 20 years.

The current interval can be extended based on the negligible change in risk and by meeting the guidance provided in Regulatory Guide 1.174, Revision 1 for risk informed decisions. The methodology used to conduct this analysis is defined in the study WCAP-16168-NP-A, Revision 3, "Risk Informed Extension of the Reactor Vessel In-Service Inspection [ISI] Interval." This study focuses on risk assessments of materials within the beltline region of the reactor vessel wall. The results of the calculations for MPS2 were compared to those obtained from the Combustion Engineering pilot plant evaluated in WCAP-16168-NP-A, Revision 3. The parameters for MPS2 are bounded by the results of the Combustion Engineering pilot plant, which qualifies MPS2 for an ISI interval extension.

DNC has concluded that the proposed alternative provides an acceptable level of quality and safety, in accordance with 10 CFR 50.55a(z)(1). The justification for the proposed alternative along with the supporting information is provided in the attachment to this letter.

The next examinations of the Examination Category B-A and B-D welds are scheduled for spring 2017 (Refueling Outage 24); therefore, DNC requests approval of this alternative by February 28, 2017 to support extension of these examinations.

If you have any questions in regard to this submittal, please contact Wanda Craft at (804) 273-4687.

Sincerely, Mark D. Sartain Vice nginerinresient Nucear

Serial No.16-036 Docket No. 50-336 Page 2 of 2 Commitments made in this letter: None

Attachment:

1) Proposed Alternative Request RR-04-22 for Millstone Power Station Unit 2 cc:

U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 Richard V. Guzman Senior Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08 C 2 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

Serial No.16-036 Docket No. 50-336 ATTACHMENT I PROPOSED ALTERNATIVE REQUEST RR-04-22 FOR MILLSTONE POWER STATION UNIT 2 MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No.16-036 Docket No. 50-336 Attachment 1, Page 1 of 6 Proposed Alternative Request RR-04-22 for Millstone Power Station Unit 2 In Accordance with 10 CFR 50.55a(z)(1)

-Alternative Provides Acceptable Level of Quality and Safety-

1. -ASME Code Comp onent(s* Affected The affected component is the Millstone Power Station Unit 2 (MPS2) reactor vessel (RV);

specifically, the following American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code, Section Xl (Reference 8.1) examination categories and item numbers covering examinations of the RV. These examination categories and item numbers are from IWB-2500 and Table IWB-2500-1 of the ASME BPV, Code Section Xl.

Category B-A welds are defined as "Pressure Retaining Welds in Reactor Vessel" Category B-D welds are defined as "Full Penetration Welded Nozzles in Vessels" EaiainCategory :Item No.:* iDescriptionll***:!~;*

B-A 81. 11 Circumferential Shell Welds B-A 81.12 Longitudinal Shell Welds B-A Bi1.21 Circumferential Head Welds B-A BI1.22 Meridional Head Welds B-A 81.30 Shell-to-Flange Weld B-A 81.40 Head-to-Flange Weld B-D 83.90 Nozzle-to-Vessel Welds B-D B3.100 Nozzle Inside Radius Section (Throughout this request the above examination categories are referred to as "the subject examinations" and the ASME BPV Code, Section Xl, is referred to as "the Code.")

2. _Applicable Code Edition and Addenda ASME Code Section X1, "Rules for Inservice Inspection of Nuclear Power Plant Components," 2004 Edition (Reference 8.1).

3. Aioolicable Code Requirement IWB-2412, Inspection Program B, requires volumetric examination of essentially 100% of RV pressure-retaining welds, identified in Table IWB-2500-1, once each 10-year interval.

The MPS2 fourth 10-year inservice inspection (ISI) interval is scheduled to end on March 31, 2020. The applicable Code for the fifth 10-year ISI interval will be selected in accordance with the requirements of 10 CFR 50.55a.

Serial No.16-036 Docket No. 50-336 Attachment 1, Page 2 of 6

4. Reason for Reauest An alternative is requested from the requirement of IWB-2412, Inspection Program B, that volumetric examination of essentially 100% of RV pressure-retaining Examination Category B-A and B-D welds be performed once each 10-year interval. Extension of the interval between examinations of Category B-A and B-D welds from 10 years to up to 20 years will result in a reduction in man-rem exposure and examination costs. DNC has concluded that the proposed alternative provides an acceptable level of quality and safety.

5. Propiosed Alternative and Basis for Use Dominion Nuclear Connecticut, Inc. (DNC) proposes to perform the fourth ASME Code required volumetric examination of the MPS2 RV full penetration pressure-retaining Examination Category B-A and B-D welds in the fifth ISI interval in 2028 plus or minus one refueling outage. The proposed inspection date for MPS2 is consistent with the schedule presented in the latest implementation plan, OG-1 0-238 (Reference 8.2).

In accordance with 10 CFR 50.55a(z)(1), an alternate ISI interval is requested on the basis that the current 1SI interval can be extended based on the negligible change in risk and by meeting the guidance provided in Regulatory Guide 1.174 for risk informed decisions (Reference 8.3).

The methodology used to conduct this analysis is based on that defined in the study WCAP-16168-NP-A, Revision 3, "Risk-Informed Extension of the Reactor Vessel In-Service Inspection Interval" (Reference 8.4). This study focuses on risk assessments of materials within the beltline region of the RV wall. The results of the calculations for MPS2 were compared to those obtained from the Combustion Engineering pilot plant evaluated in WCAP-16168-NP-A, Revision 3. Appendix A of the WCAP identifies the parameters to be compared. Demonstrating that the parameters for MPS2 are bounded by the results of the Combustion Engineering pilot plant qualifies MPS2 for an ISI interval extension. Table 1 below lists the critical parameters investigated in the WCAP and compares the results of the Combustion Engineering pilot plant to those of MPS2. Tables 2 and 3 provide additional information that was requested by the NRC and included in Appendix A of Reference 8.4.

i*

::.* Table 1:i Critical Parameter~s for the Application of Bounding Analysis for MPS2* i:l; i DomiantPresurzedThemal NRC PTS Risk Study PTS Generalization Shock (PTS) Transients in the NRC No PTS Risk Study are Applicable (Reference 8.5) Study (Reference 8.6)

Through-Wall Cracking Frequency 3.16E-07 Events per 1 9-1Eet e (TC)(efrne year (Calculated per No (TWF)year (Rfrec 84 Reference 8.4)

Freueny nd eveit ofDesgn 13 heatup/cooldown Bounded by 13 BasisenTrandSivenits fDsg cycles per year heatup/cooldown No (Reference 8.4) cycles per year Cladding Layers (Single/Multiple) SingefLaerene84 Single Layer No

Serial No.16-036 Docket No. 50-336 Attachment 1, Page 3 of 6 Table 2 provides a summary of the latest RV inspection for MPS2 and evaluation of the recorded indications. This information confirms that satisfactory examinations have been performed on the MPS2 RV.

Table: 2:* Additional Information Pertaining to Redactor Vessel 'inspection forrMPS2* *,

The latest RV ISI was conducted in accordance with the requirements of Appendix VIII of the ASME Code,Section XI, 1995 Edition with Editions and Addenda through 2000, as modified by the Performance Inspection methodology: Demonstration Initiative program. Evaluation of recordable indications was per-formed to the acceptance standards of Section Xl, 1989 Edition. Future ISis will be performed to ASME Section XI, Appendix VIII requirements.

Number of past inspections: Three 10-year ISis have been performed.

There were fourteen total indications identified in the beltline region during the most recently completed ISI. These subsurface indications are located in the upper to intermediate shell circumferential weld seam (Item 19 in Table 3), the intermediate to lower shell circumferential weld seam (Item 20 in Table 3), and the lower shell longitudinal weld seam (Item 18 in Table 3). All fourteen indications are acceptable per Table IWB-3510-1 of Section XI of the ASME Code. There are two indications within the inner 1/1 0th or inner 1" of the reactor vessel wall thickness.

The two indications are acceptable per the requirements of the Alternate Pressurized Thermal Shock (PTS) Rule, 10 CFR 50.61a (Reference 8.7).

A disposition of the two flaws against the limits of the Alternate PTS Rule is shown in the table below. No indications are located within the weld material of the reactor vessel beltline.

Number of indications found:

Through-Wall ExtntTW (i.) Scaled maximum Nubro Nubro Exet "rE(i. number of plate flaws TMVEMIN jTWVEMAx plate flaws (Axial/Circ.)

0 0.075 No Limit 0 0.075 0.375 102 2 (1/1) 0.125 0.375 40 1 (1/0) 0.175 0.375 11 0 0.225 0.375 4 0 0.275 0.375 2 0 0.325 0.375 1 0 0.375 Infinite 0 0 The fourth ISI is scheduled for 2017. This inspection will be performed Proposed inspection in 2028 plus or minus one refueling outage. The proposed inspection schedule for balance of plant date for MPS2 is consistent with the schedule presented in the latest life: implementation plan, OG-I10-238 (Reference 8.2).

Serial No.16-036 Docket No. 50-336 Attachment 1, Page 4 of 6 Table 3 summarizes the inputs and outputs for the calculation of through-wall cracking frequency (TWCF).

..... Table 3:Details of TWCF CalCulation for MPS2 at 54.Effective Full-Power Years (EFPY)i*:'...

Inputs i__:.______"_____ - i: ! i :

-. . i .... *..: * . I,:, :/: :Inter.& Lower Shell Twa11 [inch'es]i 8:

. i8941:

R

.*eactor O~obant system Temperature, Tc [0F] -N/A :1 . .. .. ...

_______________ Nozz!e Shell 'Twaij [inches], 11.06.

No. "*Region an!d component Description.. Heat N~o: . .[wt/%] .[wt%]ol :.*:!!l. [0F] [ 0F]I: n.

i:eutronicm]2*

1 Upper Shell Plate C-504-2 05809-2 0.13 0.56 1.1 89.8 22 0.243 2Upper Shell Plate 0-504-3 05809-1 0.13 0.56 1.1 89.8 15 0.243 3Upper Shell Plate 0-504-1 05804-2 0.13 0.58 1.1 90.4 22 0.243 4 Intermediate Shell Plate C-505-1 05843-1 0.13 0.61 1.1 91.3 8.1 3.83 S Intermediate Shell Plate 0-505-2 05843-2 0.13 0.62 1.1 91.5 17.5 3.83 6 Intermediate Shell Plate 0-505-3 C5843-3 0.13 0.62 1.1 91.5 5.0 3.83 7Lower Shell Plate C-506-1 C5667-1 0.15 0.60 1.1 110.0 7.0 3.83 8Lower Shell Plate C-506-3 A5518-1 0.14 0.66 1.1 101.5 -19.2 3.83 9Lower Shell Plate C-506-2 C5667-2 0.15 0.61 1.1 110.3 -33.7 3.83 10 Upper Shell Long. Weld 1-203A 120935 0.22 0.867 1.1 210.7 -56 0.243

.11 Upper Shell Long. Weld 1-2038 121935 0.22 0.867 1.1 210.7 -56 0.243 219358 & __ ____

12 Upper Shell Long. Weld 1-2030 121935 0.22 0.867 1.1 210.7 -56 0.243 13 Itereditehel Log. eld2-2193574 0.5_.1_.1 777 -5_3 13 Intermediate Shell Long. Weld 2-203A A8746 0.15 0.13 1.1 77.7 -56 3.83 14 Intermediate Shell Long. Weld 2-2038 A8746 0.15 *0.13 1.1 77.7 -56 3.83 15 Intermeit Shell Long. Weld 2-2030 A8746 0.15 0.13 1.1 77.7 -56 3.83 16 Lower Shell Long. Weld 3-203A A8746 0.15 0.13 1.1 77.7 -56 3.83 17 Lower Shell Long. Weld 3-203B A8746 0.15 0.13 1.1 77.7 -56 3.83 19 Upper to Intermediate Shell Circ. Weld 8- 33A277& 0.30 0.165 1.1 143.4 -56 0.243

___203 10137 ______

20 Inter, to Lower Shell Circ. 90136 & 0.27 0.07 1.1 124.3 -56.3 3.83 Weld 9-203 10137 ____________

*:. :: i:MethOdology Used to Calculate AT3o:. :.::ii:!.:; .: . i ::RegulJator-y Gucide1.99, Revision 213*):.::: : ii::

. ./::!.:.

:-. :::iRegion No..: :.i :.!MOX-ll;*

T [10'9 Neutron/icm2: ::(Fiuence: *AT 3 o [0 F],: . TW0*F 9 :x

' : ,- ,. ;(From Above)" : [*:*:'

] *-. 'E >> 1.0oMev]*I-:* Factor): , '

I'-: * ::ri:

Limitingl Axial Weld - AW 7 614.81 3.83 1.3467 148.14 0.00E+00 Limitingl Plate - PL 7 614.81 3.83 1.3467 148.14 5.96E-12 Circumferential Weld - CW 7 614.81 3.83 1.3467 148.14 0.00E+00 TWCF95-TOTAL(QAwTWCF95-AW + (QpLTWCF95-PL + acwTVVCF95.cw): 1 .49E-1 1 (1) Material properties based on plant-specific analysis of record (2) Fluence inputs per Reference 8.8 (3) Reference 8.9

Serial No.16-036 Docket No. 50-336 Attachment 1, Page 5 of 6

6. Duration of Proposed Alternative This request is applicable to the MPS2 1SI program for the fourth and fifth 10-year inspection intervals.

7. Precedents 7.1 "McGuire Nuclear Station, Unit 2, Relief 10-MN-002 to Extend the Inservice Inspection Interval for Reactor Vessel Category B-A and 8-0 Welds (TAG Nos. ME7329 and ME 7330)," dated September 6, 2012 (ADAMS Accession Number ML12249A175).

7.2 "Surry Power Station Units I and 2 - Relief Implementing Extended Reactor Vessel Inspection Interval (TAG Nos. ME8573 and ME8574)," dated April 30, 2013 (ADAMS Accession Number ML13106A140).

7.3 "Vogtle Electric Generating Plant, Units I and 2 - Request for Alternatives VEGP-lSl-ALT-O5 and VEGP-ISI-ALT-06 (TAG Nos. MF2596 and MF2597)," dated March 20, 2014 (ADAMS Accession Number ML14030A570).

7.4 "Catawba Nuclear Station Units I and 2: Proposed Relief Request 13-CN-003, Request for Alternative to the Requirement of IWB-2500, Table IWB-2500-1, Category B-A and Category B-D for Reactor Pressure Vessel Welds (TAC Nos. MF1922 and MF1923)," dated March 26, 2014 (ADAMS Accession Number ML14079A546).

7.5 "Sequoyah Nuclear Plant, Units 1 and 2 - Requests for Alternatives 13-1S1-1 and 13-ISI-2 to Extend the Reactor Vessel Weld Inservice Inspection Interval (TAG Nos.

MF2900 and MF2901)," dated August 1, 2014 (ADAMS Accession Number ML141888920).

7.6 "Byron Station, Unit No. 1 - Relief from Requirements of the ASME Code to Extend the Reactor Vessel Inservice Inspection Interval (TAG No. MF3596)," dated December 10, 2014 (ADAMS Accession Number ML14303A506).

7.7 "Wolf Creek Generating Station - Request for Relief Nos. 13R-08 and 13R-09 for the Third 10-Year Inservice Inspection Program Interval (TAC Nos. MF3321 and MF3322)," dated December 10, 2014 (ADAMS Accession Number ML14321A864).

7.8 "Callaway Plant, Unit 1 - Request for Relief 13R-17, Alternative to ASME Code Requirements Which Extends the Reactor Vessel. Inspection Interval from 10 to 20 Years (TAG No. MF3876)," dated February 10, 2015 (ADAMS Accession Number ML15035A148).

Serial No.16-036 Docket No. 50-336 Attachment 1, Page 6 of 6

8. References 8.1 ASME Boiler and Pressure Vessel Code,Section XI, 2004 Edition, American Society of Mechanical Engineers, New York.

8.2 PWROG Letter OG-10-238, "Revision to the Revised Plan for Plant Specific Implementation of Extended Inservice Inspection Interval per WCAP-16168-NP, Revision 1, "Risk-Informed Extension of the Reactor Vessel In-Service Inspection Interval." PA-MSC-0120," July 12, 2010 (ADAMS Accession Number MLII1153A033).

8.3 NRC Regulatory Guide 1.174, Revision I, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," November 2002.

8.4 Westinghouse Report WCAP-16168-NP-A, Revision 3, "Risk-Informed Extension of the Reactor Vessel In-Service Inspection Interval," October 2011 (ADAMS Accession Number ML11306A084).

8.5 NRC NUREG-1 874, "Recommended Screening Limits for Pressurized Thermal Shock (PTS)," March 2010.

8.6 NRC Letter Report, "Generalization of Plant-Specific Pressurized Thermal Shock (PTS) Risk Results to Additional Plants," December 14, 2004 (ADAMS Accession Number ML042880482).

8.7 NRC Code of Federal Regulations, 10 CFR Part 50.61a, "Alternate Fracture Toughness Requirements for Protection Against Pressurized Thermal Shock Events,"

Federal Register, Volume 75, No. 1, dated January 4, 2010 and No. 22 with corrections to part (g) dated February 3, 2010, March 8, 2010, and November 26, 2010.

8.8 Westinghouse Report WCAP-16012, Revision 0, "Analysis of Capsule W-83 from the Dominion Nuclear Connecticut Millstone Unit 2 Reactor Vessel Radiation Surveillance Program," February 2003.

8.9 NRC Regulatory Guide 1.99, Revision 2, "Radiation Embrittlement of Reactor Vessel Materials," May 1988.