B17886, Requests Permission to Utilize Code Case N-623, Deferral of Insps of Shell-to-Flange & Head-to-Flange of Reactor Vessel,Section Xi,Div 1, for Millstone Unit 2

Requests Permission to Utilize Code Case N-623, Deferral of Insps of Shell-to-Flange & Head-to-Flange of Reactor Vessel,Section Xi,Div 1, for Millstone Unit 2

ML20217M534
Person / Time
Site:	Millstone
Issue date:	10/18/1999
From:	Danni Smith NORTHEAST NUCLEAR ENERGY CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B17886, NUDOCS 9910270235
Download: ML20217M534 (7)

Text

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M h Nrrthenst R pe Fmy Rd. (Rouw 15S Wtuford, CT 06385

$ NuclearEnergy metooe Noaez, power station N rtheast Nudear Energy Company P.o. Box 128

, , Waterford, CT 06385-0128 (860) 447 1791 Fax (860) 444 4277 h Northeast Utuities System OCT I 8 1999 Docket No. 50-336 B17886 RE: 10 CFR 50.55a(a)(3)(i)

U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Millstone Nuclear Power Station, Unit No. 2 Reauest to Use an Alternative to ASME Code Section XI Northeast Nuclear Energy Company.(NNECO) hereby requests permission to use an alternative to the ASME Boiler and Pressure Vessel Code,- Section XI,1989 Edition, pursuant to the provisions of 10 CFR 50.55a(a)(3)(i). Specifically, NNECO requests to uti.lize Code Case ~ N423 " Deferral of Inspections of Shell-to-Flange and Head-to-  :

Flange Welds of a Reactor Vessel, Section XI, Division d " for the Millstone Unit No. 2 ,

Third 10-Year Interval inservice Inspection (ISI) Pr _ flan as detailed in Relief {'

Req'uest RR-89-24 (Attachment 1).

4 Code Case N423 (Attachment 2) was approved by the ASME Soiler and Pressure Vessel Code Committee on February 26,1999, but is not included in the most recent {I listing of NRC approved Code Cases in Revision 12 of USNRC Regulatory Guide 1.147,'" Inservice Inspection Code Case Acceptability - ASME Section XI Division 1,"

, dated May 1999.

Code Case N423 provides an alternative to the existing examination scheduling requirements for the Reactor Pressure Vessel (RPV) shell-to-flange and head-to-flange welds contained within Examination Category B-A, " Pressure Retaining Welds in Reactor Vessel," of the 1989 Edition of ASME Section XI. These examinations may currently be partially deferred to the end of a'10-year ISI interval, but total deferral is not allowed. Code Case N423 provides an option to the Licensee which would allow for total deferral of these weld examinations provided three basic conditions are met:

(1) no welded repair / replacement activities have ever been performed on these welds; f

/

-(2) the welds do not contain iderdified flaws or televant conditions that i e

currently require successive inspections in accordance with IWB- )

2420(b); and ,

(3)' the RPV is not in the first inspection interval. i 9910270235 991018 ,

PDR ADOCK 05000336 '

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c U. S. Rtgulatory Commission B17886/Page 2

'NNECO meets these three conditions for the Millstone Unit No. 2 RPV.

l Total deferral of these examinations to the end of the inspection interval would allow l the RPV ultrasonic examinations to be scheduled, in aggregate, at the same time and j- would result in significant burden reduction with no change to the examination methods or techniques requirod under the 1989 Edition of Section XI.

Deferral of these shell-to-flange and head-to-flange weld examinations to the end of a l specific plant's 10-year ISI interval is supported by the present large population of L operating reactors, Each reactor is representative of the operating conditions l

l throughout the population of reactors for a particular Nuclear Steam Supply System (NSSS) design. The volume and number of RPV welds inspected within successive 10-year intervals among these various operating reactors are essentially uniformly distributed. This being the case, examining the shell-to-flange and head-to-flange j >

welds within the population of operating reactors, sequentially for the period of a plant specific 10-year Interval, or all at the end of that interval provides the necessary assurance that any industry wide degrading condition will be detected. Additionally, performing ultrasonic examination of the RPV welds at one time, on a specific RPV, will improve the reliability and reproducibility of the ultrasonic examinations .since the procedures and techniques utilized on the population of welds will be at a uniform level l of technology. The use of this Code Case will thus close the 10-year gap in technology between various examinations now being performed on a specific RPV. The sxperience to date indicates that examinations performed on these shell-to-flange and

! head-to-flange welds have not identified any detrimental flaws or relevant conditions

! and that changing the schedule for examining those welds in aggregate at the end of j successive 10-year intervals should provide an equivalent indication of the RPV l integrity for a specific RPV. Therefore, NNECO considers this request to meet the  ;

provisions of 10 CFR 50.55a(a)(3)(i) as providing an acceptable level of quality and  !

safety.

1 l During the Third 10-Year interval, NNECO plans to use Code Case N-623 subject to NRC approval, until such time as this Code Case is incorporated into a future revision of Regulatory Guide 1,147. Upon issuance of the Regulatory Guide, NNECO will follow I all provisions in. Code Case N-623, including any exceptions or limitations as would be j discussed in the Regulatory Guide.

Review of this request is needed by March 15,2000 to support the'next Millstone Unit No. 2 refueling outage (2R13). 4 t

There are no regulatory commitments contained within this letter, i

i

U. S. Regul5 tory Commission B17886/Page 3

'Should you have any questions regarding this matter, please contact Mr. D. W. Dodson at (860) 447-1791, extension 2346.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY FOR: Raymond P. Necci Vice President - Nuclear Oversight and gulatory Affairs 1

4 David 4 Smith' Manager - Regulatory Affairs Attachments: (2)

1. Relief Request RR-89-24

2. ASME Code Case N-623 i

cc: H. J. Miller, Region I Administrator R. B. Eaton, NRC Senior Project Manager, Millstone Unit No. 2 D. P. Beaulieu, Senior Resident Inspector, Millstone Unit No. 2

p 6

! Docket No. 50-336

B17886 i

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! Attachment 1 Millstone Nuclear Power Station, Unit No. 2 Relief Reauest RR-89-24 l

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October 1999 t

U. S. Regulatory Commission B17886/ Attachment 1/Page 1 Attachment 1 Reauest To Use Code Case N-623 As An Alternative To ASME Section XI Relief Reauest RR 89-24 Relief Reauest: RR-89-24 Code Class: 1 Zone; 1-01,1-02 Code Cateaorv: B-A, Pressure Retaining Welds in Reactor Vessel

~ ltem No.: B1.30, Shell-to-Flange Weld B1.40, Head-to-Flange weld Code Reauirement:

Section XI of the ASME B&PV Code,1989 Edition, Table IWB-2500-1, requires that the' RPV shell-to-flange weld be volumetrically examined once each inspection interval and the RPV head-to-flange weld be surface and volumetrically examined once each inspection interval. The footnotes to the Table provide partial deferrals for both of these welds, but in no case are they allowed to be totally deferred to the end of the interval.

Code Relief Reauested:

Pursuant to the provisions of 10 CFR 50.55a(a)(3)(i), relief is requested to utilize the altemative requirements of Code Case N-623 " Deferral of Inspections of Shell-to-Flange and Head-to-Flange Welds of a Reactor Vessel, Section XI, Division '1," for the Millstone Unit No. 2 Third 10-Year Interval inservice inspection (ISI) Program Plan.

Reason for Relief.

Code Case N-623 provides an alternative to the examination scheduling requirements for the reactor pressure vessel (RPV) shell-to-flange and head-to-flange welds contained in Examination Category B-A, " Pressure Retaining Welds In Reactor Vessel," of the 1989 Edition of ASME Section XI. These examinations currently may be partially deferred to the end of a 10-year inservice Inspection (ISI) interval, but total deferral is not allowed. Code Case

i

' ' U. S. Regulttory Commission B17886/ Attachment 1/Page 2 1 N-623 provides an option to the Owner for total deferral of these weld

' examinations provided three basic conditions are met:

(1) . no welded repair / replacement activities have ever been performed on these welds;  !

(2) the welds do not contain identified flaws or relevant conditions that currently require successive inspections in accordance with IWB-2420(b); and (3) the RPV is not in the first inspection interval. I NNECO meets these conditions for the Millstone Unit No. 2 RPV Total deferral of these examinations to the end of the inspection interval would allow the RPV ultrasonic examinations to be scheduled, in aggregate, at the same time and would result in a significant burden reduction with no change to the examination methods or techniques required under the 1989 Edition of Section XI.

Deferral of these shell-to-flange and head-to-flange weld examinations to the end of a specific plant's 10-year ISI interval is supported by the present large  ;

population of operating reactors. Each reactor is representative of the operating conditions throughout the population of reactors for a particular Nuclear Steam Supply System (NSSS) design. The volume and number of RPV welds inspected within successive 10-year intervals among these various operating reactors are essentially uniformly distributed. This being the case, examining the shell-to-flange and head-to-flange welds within the population of operating reactors, sequentially for the period of a plant specific 10-year interval, or all at the end of that interval provides the necessary assurance that any industry wide j degrading condition will be detected. Additionally, performing ultrasonic examination of the RPV welds at one time, on a specific RPV, will improve the {

reliability and reproducibility of the ultrasonic examinations since the '

procedures and techniques utilized on the population of welds will be at a uniform level of technology. The use of this Code Case will thus close the 10- ]

year gap in technology between various examinations now being performed on a specific RPV. The experience to date indicates that examinations performed on j these shell-to-flange and head-to-flange welds have not identified any {

detrimental flaws or relevant conditions and that changing the schedule for i examining these welds in aggregate at the end of successive 10-year intervals should provide an equivalent indication of the RPV integrity for a specific RPV.

Therefore, NNECO considers this request to meet the ' provisions of 10CFR50.55a(a)(3)(i) as providing an acceptable level of quality and safety.

U. S. Regulatory Commission B17886/ Attachment 1/Page 3

' Proposed Alternative

• During'the Third 10-Year Interval, NNECO plans to use Code Case N-623 subject to NRC approval, until such time as this Code Case is incorporated into a future revision of Regulatory Guide 1.147. Upon issuance of the Regulatory Guide, NNECO will follow all provisions in Code Case N-623, including any exceptions or limitations as would be discussed in the Regulatory Guide.

J Docket No. 50-336 B17886 )

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Attachment 2 Millstone Nuclear Power Station, Unit No. 2 ,

1 ASME Code Case N-623 October 1999

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U.S. Nuclar Regulttory Commission ,

B17886/ Attachment 2/Page 1 Attachment 2 1

ASME Code Case N-623 case N-623 naus or Ames motuma AND PeSeeUeE VuemeE. Cone Appeeset osem poteenry as, esse see mmene New ser medonnan and ery eeschmemen messe.

Case N423 of shanage welde and head-to-Seege welds of Deferred af leapecelone of htaB4e Flease and a reecear veneet may be defened e the end of the Head 4e-Flange Walde af a Esector Vessel W laserval without :- ^ "r,, perdal =amian-Seselse II, DMains 1 ticas frees the dan 6e face if the following condidone em met:

Anguiry* What alternative rules may be used in line (e) No weldedi--+'-t

- .' - ^ activities have ever of Table 1, ha=&= siam Cesagory B-A (Psogram B), been peefonned on the shell4o-nange or head-so.

"Paseme Roselaing Weide in Reeseer Vessel", Seo-Aaese weld.

des XI, DIAsion' t to allow deferral of I , '--- -

@) Neither the sbou-to Sesgo weld sor hoed-to-Amese of *W **3ds *=d Wase **his of weld cassaim %msed sewe or senevens condidone a sencear vessei?

, abes W @ mana==ive inspeedone la accord-Jteply: k in the ar am of the Comsnines M as a ance with IWB-2420(b).'

(c) The vessel is not in the Grut inspection interval.

en altermedve to the saistieg , ineroselon l

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