ML20115B527

Forwards Request for Relief from ASME Section XI Code Inservice Insp Schedule Requirements for post-repair Hydrostatic Tests of Once Through SG Secondary Side, Including Portions of Main Steam & Emergency Feedwater Sys

ML20115B527
Person / Time
Site:	Three Mile Island
Issue date:	10/09/1992
From:	Broughton T GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
C311-92-2132, NUDOCS 9210160117
Download: ML20115B527 (8)

Text

_... _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - . _ _ _ -

GPU Nuclear Corporation h Q gf Post Office Box 480 Route 441 South Middletown, Pennsylvania 170$7 o191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:

117-948-8005 e

October 9, 1992 C311-92-2132 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

Three Mile Island Nuclear Station Unit 1, (THI-1)

Docket No. 50-289 Operatir.g License No. OPR-50 Relief from ASME Section XI Code Inservice Inspection (151)

Schedule Requirements - Post Repair Hydrostatic Tests In accordance with 10 CFR 50.55a(g)(5), if the licensee determines that coriformance with certain Code requirements is impractical for its facility, the licensee shall notify the Commission and submit information to support the determinations. The purpnse of this letter is to request relief from the schedular requirements of the ASME Section XI Code, paragraph IWA-4400(a), to perform a hydrostatic pressure test of the Once Through Steam Generator (OTSG) secondary side including portions of the Main Steam, Feedwater and Emergency Feedwater Systems. GPU Nuclear requests relief to defer the test to THI-l's Cycle 11 Refueling Outage (11R), currently scheduled for September 199F. This will result in a delay of approximately five months in addition to ons year extension allowed by the Code. This request also changes our connitment' to complete 100% of the total number of system hydrostatic tests by the end of the first period of the second ISI interval.

The current Edition of the Code requires a hydrostatic pressure test as a result of welded repairs associated with replacement of 0TSG vent and drain valves, Emergency Feedwater Flow Verturis, and Main Feedwater nozzles installed during previous outages. GPU Nuclear's request for relief, provided in Attachment 1, demonstrates the impractical 1ty of the current schedule for performing this test based on 1) alternative tests-and non-destructive GPU Nuclear Letter (C311-91-2010), dated April- 19, 1991, inservice Inspection for the Second Ten-Year Interval - Plans and Schedules, Attachment Basis Document Number 1. s2.0. P.6, 15. .

9210160117 921009 PDR ADOCK 05000289 13b ]J P PDR GPU Wuclear Corporahon is a subsidiayof Genera! Pubhc Uhhhes Corpotabon -

h' ji h

-m-_-_-_m._

i Document Control Desk C311-92-2132 Page 2 of 3 examinations (NDE), 2) no benefit to be gained from the test, and 3) the likelihood that the requirement for this test will be deleted by the ASME and NRC prior to llR.  :

g This letter supercedes our letter, dated March 8,1992, which requested NRC appro"al to use ASME Code Case N-498 as an alternative to performing system hydrostatic pressure tests including the Main Steam System. Subsequent to our letter, Code Case N-498 was approved by the NRC as published in Regulatory Guide 1.147, Revision 9, dated April 1992. '

In a letter to Virginia Power Co. (Code Inquiry 92-012), the ASME has stated that Code Case N-498 does not apply to hydrostatic tests of welded repairs, replacements, and. modifications (welded repairs) which, in accordance with Code Case N-416, have been deferred. Code Case N-416 allows deferral of hydrostatic tests where piping cannot ba isolated by existing valves or that requires securing safety or relief valves for isolation until the next regularly scheduled hydrostatic test. Although Code Case N-498 eliminates the requirement for a regularly scheduled system hydrostatic test, the ASME's response to the Code Inquiry states that for the purposes of satisfying the Code requirements for repairs and replacements, a hydrostatic test would be required at or before the originally scheduled hydrostatic test date.

In order to extend the applicability of Code Case 498 to welded repairs, Code Case (Draft) N-XXX, " Alternate Pressure Test Requirement for Repairs, Replacement and Modifications." was drafted for review during the August 1992 meeting of the ASME Section XI Code Committee. The draft code case will allow substittb on of NDE in conjunction with operational leakage tests for hydrostatic pressure tests of welded repairs. The Committee did not rule to approve the Code Case (Draft) N-XXX in August as time did not permit. This action was deferred to the next meeting of the Code ummittee in December 1992. After Codt Case (Draft) N-XXX is approved by the Code Committee, Nhc approval is expected and this would be documented in the next revision of Regulatory Guide 1.147.

GPU Nuclear believer that action by tha ASME and NRC will eliminate the requirement for a hydrostatic test following welded repairs. Elimination of the requirement for hydrostatic test of the OTSG secondary side will reduce cost, critical path outage time, and total radiation exposure (that associated with personnel setting up for and performing the test) without reducing the level of cuality or safety. A hydrostatic pressure test of the OTSG secondary-4 side woulc cost several hundred thousand dollars and woulti consume several days of critical path time. It'is recognized in Code Case N-498 that the increase in pressure to perform a hydrostatic test does not significantly stress or challenge the pressure boundary.

To assure compliance with Code requirements, the post-repair hydrostatic test of the OTSG secondary side must be performed prior to April 19, 1994. The last scheduled outage for performing this test is THI-l's Cycle 10 Refueling Outage (10R) which is scheduled for September 1993. GPU Huclear reouests that s

e Document Control Desk C311-92-2132 Page 3 of 3 the NRC approve relief from Code requirements ano grant an extension of the ISI schedule for performing the post repair hydrostatic test of the OTSG secondary side until TH1-l's Cycle 11 Refueling Outage (llR), scheduled for September 1995. Extersion of the ISI schedule for this test until llR would allow additional timc for the ASME Section XI Code committee to t' axe action and approve Code Case (Draft) N-XXX or a similar one which would eliminate the system hydrostatic test requirements for welded repairs.

In order to support our planning effort for 10R, NRC app oval is needed prior to January 1993. This test is on the 10R Outage critical path and therefore '

early resolution of this issue is required to avoid unnecessary planning and scheduling activities or rework of such effort.

Sincerely, T

[(as T. G. Broug iton Vice Presit ent and Director, THI-l HRK Attachment cc: Administrator, Region I THI-l Senior Resident inspector THI-l Senior Project Manager

C311-92-2132

. Attachment 1 Page 1 of 5 THI-l Relit T.equest COMPONENT DESCRIPTION:

Welded pipe repairs as follows:

1) Approximately twenty (20) field tie-in weld repairs associated with OTSG vent and drain valves (l\" and 2"),

2) Field tie-in welds associated with replacement of the Emergency feedwater Flow Venturis, and

3) Field tie-in welds associated with replacement of the r,ain feedwater nozzles including several elbows immediately upstream of the nozzles. (OTSG "A" and "B" each contain thirty-two (32) 3" Main Feedwater nozzles.)

The hydrostatic tesi. envelope for these components includes the Main

~

Steam System from the Once Through Steam rsenerator (OTSG) secondary side extending to the Main Steam isolation Valves, the Emergency feedwater Block Valves (EF-V52A/B/C/D), and the Main feedwater Check Valves (FW-V12A/B).

APPLICABLE CODi EDITION:

In accordance with 10CFR 50.55a(g)(4)(ii), GPU Nuclear adopted the 1986 Edition of the ASME Section XI Code for THI-l's second 120 menth inspection interval which began on April 20, 1991. Although the ASME Code Section XI 1986 Edition is currently anplicable, the welded repairs which are the subject of this relief request were conducted prior to April 20, 1991 in accordance with the 1974 Edition through Summer 1975 Addenda.

ISI CLASS: 2 ISI DRAWING NO..

L ID-ISI-FD-001 - Main Steam System and Drainage ID-ISI-FD-009 - Emergency feedwater and feedwater Systems D_ESItiN PREE!BE:

Main Steam System 1050 psig Emergency Feedwater System 1100 psig Main feedwater System 1150 psig NORMAL OPERATING PRESSURE: 900 psig CODE REOUIREMENT:

ASME Section XI, IWA-4400(a) requires a hydrostatic test following repairs by welding. (This requirement was included in earlier Code Editions as IWA-4210.)

.C311-92-2132

. Attachment 1 Page 2 nf 5 i RLIEF BEING RE00ESTED:

i GPU Nuclear requests schedular relief for the above requirement until

. TMI-l Cycle 11 Refueling Outage (llR) pending action by the ASME i

Section XI Code Committee which would eliminate this requirement for a hydrostatic test. This wotid result in an extension of approximately five months in addition to the one year extension allowed by the Code.

It is noteworthy thet THI-1 lost four months from the current period of the ISI program as a result of the update to the 1986 Edition of the Code #1 April 20, 1991. The newer Edition of the Code divides the 10-year ISI interval into three unequal periods (1st period months, 1 2nd period mr iths, and 3rd period = 36-months) rather the three equal 40-month periods. )

ALTERNATIVE EXAMINATIOR Other reauirements for NDE in addition to a VT-2 leakage examination at nominal operating pressure provide sufficient test requirements such S that the additional requirements for a post repair hydrostatic test should be eliminated. A VT-2 leakage examination will be conducted in 10R as is required each ISI period in accordance with the current

Section XI Program.

BACKGROUND:

Code Case N-411:

NRC-approved Code Case N-416 allows deferral of hydrostatic tests required for repair or replacement (welded repairs) of Class 2 piping that cannot be isolated by existing valves or that requires securing

safety or relf ef valves for isolation. The Code Case allows these tests to be deferred to the next regularly scheduled hydrostatic test required, provided that 1) a VT-2 leakage examination is conducted and

2) the repair or replacement welds have been volumetrically examined for full penetration welds or surface examined for partial penetration weld:.

Code Case N-498:

NRS-approved Code Case N-498 allows a System leakage test at nominal operating pressure (IWB-5221) at or near the end of each inspection interval as an alterative to IWB-5222 " System iNdrostatic Tests" for Class 1 and Class 2 piping required by Table IW 2500-1, Category B-P.

Code Inouiry 92-012:

Code Inquiry 92-012 states that Code Case N-498 does not apply to repairs and replacements.

• 0 raft" Code Case N-XXX:

For Class 1 and Class 2 piping, this draft code case allows substitution of NDE in onjunction with operational leakage tests in place of the requireme for hydrostatic tests. This code case may be approved by ASME in meeting scheduled for Decerr.ber 1992.

C311-92-2132 Attachment 1 Page 3 of 5 i

1 SIS FOR.RE0 VESTING RELIEF:

Apnlicability:

This request applies to the following THI-l Class 2 welded repairs:

1) OTSG vent and drain valves,

2) Main Feedwater nozzle replacements, and '

3) Emergency Feedwater flow venturis.

I i I

In accordance with Code Case N-416, a VT-2 leakage examination and either a volumetric examination for full penetration or a surface l examination for partial penetration welds were required and the  !

hydrostatic test was deferred until 10R.

~

GPU Nuclear recently performed a review of the documentation from previous weld repairs. This review showed that when Main Feedwater I nozzles were replaced, the nozzle welds received a surface examination l

, in addition to the required volumetric examination. The results of our l- review found that all NDE were completed to satisfy Code Case 416 with the exception of those associated with the partial penetration weld repairs of 1%" 0TSG drain valves MS-V74A/B in 1988. Although all original construction test and inspection requirements (B31.1) were i

fulfilled, a surface examination of MS-V74A/B partial penetration welds repairs was inadvertently omitted. Surface examinations for MS-V74A/B will be performed at the next scheduled outage, no later than 10R.

Justification for Reouestina Relief:

The only way to hydrostatically test the above welded repairs is to pressurize the entire secondary side of the OTSGs out to the Main. Steam Stop Valves. This boundary would include the Main Steam Safety Valves 4 (MSSVs). The Code-required hydrostatic test pressure (1300 asig) is much greater than the setpoint for the eighteen (18) MSSVs, witch

includes sixteen (16) - 6" X 10" valves and two (2) - 3" X 6" valves. '

i Gagging the valves could bend the spindles. To assure operability of the MSSVs it would be necessary to send some or all of them offsite for .

l testing in a test facility prior to operation. Blanking off the MSSVs would likely result in a need to retest some or all of the valves. GPU Nuclear believes that it would be impractical to remove and blank these valves only for the purpose of performing the Code-required hydrostatic test.

THI-l Technical Specificationt (TS 3.1.2.2) require that OTSG shell temperature be maintained at or above 100*F whenever the OTSG secondary

, side is pressurized above 200 psig. TS 3.4.1.2.1 also requires the operability of at least two (2) MSSVs per OTSG prior to raising Reactor Coolant System (RCS) temperature above 250*F allowing that the others be

, tested during the heatup. These requirements place constraints on plant operation which result in adding critical path time to an outage in order to perform the OTSG secondary side hydrostatic test.

In accordance with Code Case N-416, it would be acceptable to delay hydrostatic pressure tests of welded repairs completed.at the beginning of a 10-year interval until the end of the 10-year interval.

-- = - _ _ _ _ . . - - _ _ - _ _ . _- - _.

-C311-92-2132

. Attachment 1 Page 4 of 5 Considering that a hydrostatic test can be delayed for almost an entire 10-year interval, performing a hydrostatic pressure test for the purpose of qualifying welds that have been in service for that amount of time would be of marginal value. Volumetric examination of full penetration welds and sur N e examination of partial penetration welds in combination witn a VT-2 leakage examination at nominal operating pressure provides a greater level of assurance than hydrostatic tes,ts.

It is recognized in Code Case N-498 that the increase in pressure to perform a hydrostatic test does not significantly stress or challenge the pressure boundary.

A hydrostatic pressure test of the OTSG secondary side would cost several hundred thousand dollars and would consume several days of  ;

critical path time. GPU Nuclear considers the hydrostatic test of the i

0TSG secondary side for the above weld-repairs would be a hardship with i essentially nn benefit. In 10R GPU Nuclear will perform a VT-2 leakage ,

4 examination at operating pressure of the OTSG secondary side (~900 psig) I to observe leakage. This in combination with the surface and volumetric

. examinations which have been performed and surface examinations for MS-V74A/B which will be performed during 10R are considered to be sufficient wittout an additional hydrostatic test of the OTSG secondary side.  :

An estimated four days o# critical path time would be recuired to

, perform a post re) air hydrostatic test of the OTSG seconcary side.

There would also )e personnel exposure dose associated with the need to install and remove hydrostatic test equipment, remove and blank relief i valves, and isolate and restore the valve lineup required for the hydrostatic pressure test. Although the dose would not be expected to be high, there would be a benefit toward keeping doses as low as reasonably achievable (ALARA) if the test were not required.

GPU Nuclear has completed approximately thirteen (13) system hydrostatic tests at Thl-1 and never found weld or piping through wall leakago. We believe that there would be no technical merit to performing a i

hydrostatic test of the OTSG secondary side considering the NDE which have been completed and the surface examinations for MS-V74A/B which will be performed in 10R in addition to a VT-2 leakage examination at nominal operating pressure prior to startup following 10R.

There is insufficient benefit to warrant the risks and resource impact associated with a hydrostatic test of.the OTSG secondary side. Leakage would not be appreciably rore apparent using the hydrostatic pressure test as compared with a VT-2 ;isual examination at nominal operating pressure becausc the applicable system hydrostatic test pressure would not apply significant additional stress to the piping.

GPU Nuclear believes that action will be taken by the ASME and NRC to

, eliminate the Code requirement for hydrostatic test of welded repairs.

Deferral of this test until such action has been taken to eliminate the recuirement will reduce cost, critical path outage time, and total raciation exposure to personnel without reducing the level of quality or safety.

.C311-92-2132

. Attachment 1 Page 5 of 5 To assure compliance with Code requirements without action by the Code Committee followed by NRC approval, a post-repair hydrcstatic test of the OTSG secondary side must be performed prior to April 19, 1994.

Without Code relief, the last scheduled outage for performing this test is 10R which is scheduled for September 1993. GPU Nuclear requests that the NRC ap) rove relief from Code requirements and grant an extension of the ISI scledule for performing the post ru air hydrostatic test of the OTSG secondary side during IIR, which is scleduled for September 1995.

Extension of the ISI schedule for this test until llR would al~iow additional time' for the ASME Section XI Code committee to take action and approve Code Case (Draft) N-XXX or a similar one which would eliminate the system hydrostatic test requirements for welded repairs.

In order to suppcrt our planning effort for 10R, NRC approval is needed prior to January 1993.

4 This amounts to a five month extension in addition to the 12 month extension allowed by the Code to pe mit examinations to coincide with plant outages.

I

\

- _______ . _ _