ML20101K215

Updates Plans to Address IGSCC During Upcoming Cycle 14R Refueling Outage

ML20101K215
Person / Time
Site:	Oyster Creek
Issue date:	06/26/1992
From:	Devine J GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
5000-92-3030, C320-92-2142, NUDOCS 9207020145
Download: ML20101K215 (3)

Text

c

-y.

4-6 MNuclear c ::; "s:: m os, GPU Nuclear Corporation 201-316 7000 TELEX 136-482 Writer's Direct Dial Nurnber:

June 26, 1992 5004-92-3030 C320-92-2142

-U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C.-

20555

Subject:

Oyster Creek Nuclear Generating Station Facility License No. DPR-16 Docket No. 50-219

'iutage 14R IGSCC Activities This letter updates GPU Nuclear (GPUN) plans to address IGSCC during the upcoming Cycle 14R refueling outage. C'.anges to our inspection and mitigation program are as follows:

1)

LAST STAINLESS STEEL WElb JOINTS The NRC staff's letters dated June 28, 1991 and September 12, 1991 req::ested that GPUN determine carbon content and ferrite number of cast stainless steel components in the Recirculation System.

Information obtained from a documentation review was provided by our letter dated February 26, 1992. After subsequent telephone discussions with the staff we have decided to augment that information with field measurements and analysis. Specifically, during the 14P. outage for the recirculation pump casings, suction elbous and intervening weld material, ferrite will be measured..In addition, since material composition records could not be

- found for the weld metal, samples of each of the five welds will be taken during 14R and analyzed. This additional information will help to provide a more complete understanding of the resistance to IGSCC for these five weld joints.

2)

IGSCC MITIGATION CHANGES As previously indicated in our December 9, 1991 Integrated Schedule update, the continuing improvement program for piping welds inside the drywell has been rescheduled to the 15R refueling outage and the repair / replacement of reactor vessel closure head welds is canceled.

Mitigation measures to closure head welds will be based on the future inspection.results.

92070PO145 920626 PDR ADOCK 05000219

{,>

pyg P

GPU Nuclear Corporation is a subsidiary of General Public UtAt:es Corporat;on M[

//O w

_r._

- - - C330 92-2142 Page 2 3)

RECIRCULATION AND ISOLATION CONDENSER SAFE-END TO PIPING WELDS-During original construction the inside diameter and outside diameter of these welds were clad with 308L stainless steel.

The cladding extends beyond the heat a " acted zone.

This IGSCC mitigation Teature was documented in the original Oyster Creek FSAR (Facility Description and Safety Analysis Report, Amendments 40 and 43).

To date, we have exam r.*:d both "olation condenser welds and six of ten recirculation welds of this-typ without detecting IGSCC.

For the above reasons, wo now consider these twelve (12) safe-end-to-pipe welds to be in Category A.

Also, these welds have been removed from our strms improvement program although both isolation condenser welds and both recirculation loop C welds have been stress improved.

All safe-end-to-nozzle welds will continue to be regarded as non-resistant with applicable iaspection schedules.

4)

REACTOR WATER CLEANUP OUTSIDE SECOND IS0tATION VALVE Currently, our plans are to complete the Bulletin 89-10 actions for the reactor water cleanup (RWCU) isolation valves during the 14R outage. As suggested by Gentric Letter 88-01, Supplement 1, we propose a change to the inspection scope for RWCU welds outside the second isolation valve.

We believe these welds need not be inspecttd for the following reasons:

100%

radiography was specified and met during original construction.

- No repairs were necessary during construction.

- _0perating stresses for these welds are lower compared with RWCU welds inside the second valve.

Reactor water chemistry has been historically good with superior performance during the last several cycles. While not always available nor meeting recommended limits Hydrogen Water Chemistry has been applied during the last two operating cycles.

4

- No leaks or IGSCC indications have been found to date in any RWCU weld inside or outside the second valve.

- Weld crown reduction for all welds including RWCU has been very thorough requiring QC acceptance prior to inspections, thus facilitating the inspection process and assuring high quality exams.

- An approximate 5 m>.n-rem reduction in radiation dose can be achieved b.Y M t ir.,pecting welds outside the second valve.

- By completing tle G.L. 89-10 activities during 14R for RWCU isolation valves it will be shown that they can isolate any break.

l

-4 C'330-92-1142 Pa,ge 3

~

Open issues concerning our G.L. 89 10 program may have the potential to impact com)letion of RWCU valves by the 14R outage.

if any issues remain unresolved

- suc1 that completion is not possible, we will implement RWCU IGSCC inspections outside the second isolation valve in accordance with our existing program.

Pursuant to Oyster Creek Technical Specifici :on 4.3.I, we request the NRC staff's concurrence with the program changes aescribed in Items 3 and 4 above.

Very truly yours, f 0 4 { ;/c ~ l} d h d - e y v.

J. C. DsVine, Jr'.

6 Vice President and Director Technical Functions JCD/PFC/amk cc: Administrator, P.egion I NRC OC Project Manager NRC OC Resident Inspector a

p 1

_