ML20151K808

Forwards Response to Generic Ltr 88-01, Potential for IGSCC in BWR Austenitic Stainless Steel Piping. Current Plans Do Not Exist to Replace Piping Due to Measures Taken During Const

ML20151K808
Person / Time
Site:	Perry
Issue date:	07/29/1988
From:	Kaplan A CLEVELAND ELECTRIC ILLUMINATING CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
GL-88-01, GL-88-1, PY-CEI-NRR-0894, PY-CEI-NRR-894, NUDOCS 8808030285
Download: ML20151K808 (4)

Text

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4 .. s YHE CLEVELAND ELECTRIC ILLUMIN ATING COMP ANY P.O. F .( 97 e PERRY, OHIO 44081 m TELEPHONE (216) 259 3737 et ADDRESS-1o CENTER ROAD Serving The Best Location in the Nation PERRY NUCL EAR POWER PLANT Al Kapten W .FAc1JENT NUCLEAR Group Jt.ly 29, 1988 PY-CE1/NRR-0894 L U.S. Nuclear Regulatory Commission Document Cc, trol Desk Washing *on, .C. '!0555 Percy Nuclear Power Plant Docket No. 50-440 Response to Generic Letter 88-01, Potential f v IGSCC dn BWR Austenitic Stainless steel Piping Centlemea:

Revised NRC staff positions on intergranular stress corrosion cracking (IGSCC) were defined in the Generic Letter 88-01, for licensee evaluation and response.

The attached C'eveland Electric illuminating Company responses on piping replace.en., IuSCC mitigation, augmented inspection, leak detection and noti'icction. are keyed the to corresponding Generic uetter text.

If you have fuccher questions, plea's feel free to cail.

Very truly yours, W

Al Kaplan Vice President Nu,: lear Gcoup AK:njc cc: K. Connaught-T. Colbur.

USNRC Region i

h0 t 'y s5 880729 hS]': )CK 0500044o p ,

T'DC

. s Attschmsnt 1 PY-CEI/NRR-894 L Page 1 of 3 Perry Responses to Generic Letter 88-01 Item 1

[ Identify] your current plans regarding pipe replacement and/or other measures taken or to be taken to mitigate Intergranular Stress Corrosion Cracking (IGSCC) and [to] provide arsurance of continued long term piping integrity and reliability.

Responset CEI has no current plans to replace stainless steel piping or to take additional measures described in Generic Letter 88-01, due to measures taken during construction cf Perry to provide assurance of continued long term piping integrity and reliability- The stainless steel piping at Perry was fabricated, velded, inapected and controlled as described in Sections 5.2.4 and 5.2.5 of the Perry SER (NUREG 0887) and its supplements 5 and 7. Vith the exception of inconel veld metal, CEI finds no significant difference in material at Perry and the Generic Letter 88-01 requirements for reactor coolant pressure boundary materials. New information in the Generic Letter regarding IGSCC susceptibility for inconcel mar.erial is further discussed under item 2.

The Perry reactor coolant pressure boundary had no evidence of cracking from preservice inspection results.

Item 2: [ Define] an Inservice Inspection (ISI) Program to be implemented at the next refueling outage for austenitic stainless steel piping covered under the scope of this letter that conforms tc the staff positions on inspection schedules, methods and personnel, and sample expansion included in this letter.

Response: The Perry reactor coolant pressure boundary is made of austenitic stainless steel of IGSCC category A accocding to Table 1 of Generic Letter 88-01, with the exception of Inconel 182 velds hetveen reactor vessel nozzles and safe-ends. These 25 nozzle to safe-end velds are identified es items B5.10 and B5.20 in the Perry 10 year ISI Program Plan *.

The present classification of the PNPP reactor pressure vessel nozzle safe-end welds are IGSCC Category "D" as delineated in the referenced table, and vill be examined accordingly. The 10 Year ISI Program Plan vill be revised to accommodate this schedule.

In accordance with Generic Letter 88-01, if CEI elects to apply stress improvement methods for the IGSCC Category "C" safe-end elds, then the IGSCC Category will change along with the examination scheduling requ'rements. A separate notification vill be provided at that time vh: .h vill include the proposed examination schedule changes, and specific stress improvement procedures.

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• Documeist number ISI-GEN-T2004 Rev. O dated Jen"ary 21, 1987, Section l? -A pages 51-55. Submitted by PY-CEI/NRR-0614 L on March 31, 1987.

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T Attachmtnt 1 6* PY-CEI/NRR-0894 L Page 2 of 3 Item 3: [ Change] the Technical Specifications to include a statement in the section on ISI that the Inservice Inspection Prograa for piping covered by the scope af this letter vill be in conformance with the staff positions on schedule, methods and personnel, and sample expansion included in this letter (see enclosed model BVR Standard Technical Specif!:ation). It is recognized thst the Inservice Inspection and Testing sections may be removed from the Technical Specifications in the future in line with the Technic-1 Specifications Improvement programs. In this case, this.

requirement shall remain with the ISI section when it is included in an alternative document.

Response: CEI plans to incorporate these changes in the ISI program.

The commitment for performing ISI related examinations is presently documented in the PNPP 10-Year Inservice Inspection Program Plan in addition to Sections 3.4.8 and 4.0.5 of the plant Technical Specifications. The examination requirements pertaining to the IGSCC Category "A" and "D" material of the Generic Letter vill be incorporated into the ISI Program Plan (referenced in item 2),

rather than adding a generic statement to the Technical Specifications. This alternative meth d of documenting specific commitments to the Generic Letter recommendations vill properly control the activities conducted under the ISI program at PNPP.

Item 4: [ Confirm] your plans to ensure that the Technical Specification related to leakage detection vill be in conformance with the staff position on leak detection included in this letter.

Response: The Clevelend Electric Illuminating Company has carefully considered the recommended changes to the leak detectior. Technical ,

Specifications. One of the recommendations regarded operability of sump leakage measurement instruments. The recommendation was that for plants operating with any IGSCC Category D, E, F or G velds at least one of the leakage measurement instruments associated with i each sump shall be operable, and the outage t.me for inoperable  !

instruments shall be limited to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or immediately-initiate I an orderly shutdown. The Perry plant is currently in its first  !

operating cycle, and as noted in item 1 above, the Perry reactor  !

coolant pressure boundary had no evidence of any cracking from its l preservice inspections Industry experience has shown that this i cracking is not yet a safety concern for a plant such as Perry. As I noted in item 2, should CEI elect to apply stress improvement methods to the safe-end velds, then no IGSCC Category D. E, F or G j velds vould exist and this recommendation vould not apply. 1 Implementation of this recommendation at this time vould therefore offer no safety improvement, and carries an extremely negative cost-benefit implication.

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.. s Attachmsnt 1 PY-CSI/NRR-0894 L Page 3 of 3 CEI therefore intends to (1) implement augmented inspection ef the 25 susceptible velds, as specified in the Generic Letter and (2) continue to evaluate stress improvement as described in item 2.

Another recommendation concerned shutdowns to investigate leakage rates. The recommendation was that plant shutdown should be initiated for inspection and corrective action when, within any period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or less, any leakage detection system indicates an increase .a rate of unidentified leakage in excess of 2 gpm or its equivalent, or when the total unidentified leakage attains a rate of 5 gpm or equivalent, whichever occurs first. The Perry plant already is restricted to 5 gpm leakage from unidentified sources by the Technical Specifications. This limit is shown to be quite conservative by USAR Section 5.2.5.5 vhich identifies that this 5 gpm leakage rate is a small fraction of the calculated flov from a critical crack in a primarv system pipe. Should a leak develop for whatever reason, thit carrent limit is considered sufficient to allow for plant shutdown to investigate. Also, as discussed above, cracking from IGSCC is not a safety concern at this point in the Perry operating lifetime.

Although no desirable improvement in the margin of safety is evident, if stress improvement is not chosen to be performed on the subject velds during upcoming refueling outages, CEI would consider the addition of the standard Technical Specification requirement associated with service sensitive IGSCC materials that imposes a shutdown if leakage rates increase 2 gpm over a four-hour period.

Again, CEI intenda to consider this Technical Specification change in conjunction with evaluation of stress improvement. As a minimum however, this requirement vould have to allow for reestablishing background rates of leakage during plant startups.

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The staff position on leak detection also provided a definition for unidentified leakage. During the development of the Perry Technical Specifications, appropriate dedinitions for identified ,

and unidentified leakage were incorporated, and do not require l change at this time.

l Item 5: In accordance with 10 CFR 50.55a(g), [ confirm) your plans to notify ;

the NRC of any flaws identified that do not meet IVB-3500 criteria  ;

of Section XI of the Code for contint:d operation without '

evaluation, or a change found in the condition of the velds previously known to be cracked, and ycur evaluation of the flavs for continued operation and/or ycur "pair plans.

Response: CEI confirms that such notification vill be provided,