ML20147E460

Responds to 870916 Request for Addl Info on Insp Rept 50-029/87-07 Conducted During 870511-29 Re Steam Generator Surveillance Program Improvements.Intentions in Area of Each Respective Proposal Encl

ML20147E460
Person / Time
Site:	Yankee Rowe
Issue date:	01/12/1988
From:	Heider L YANKEE ATOMIC ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
FYR-88-08, FYR-88-8, NUDOCS 8801210121
Download: ML20147E460 (4)

Text

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%o Tetzphone (617) 872 8100 TWX 710-3801619 YANKEE ATOMIC ELECTRIC COMPANY ynaN s_ -

1671 Worcester Road, Hamingham, Massachusetts 01701 January 12, 1988 FYR 88-08 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

References:

(a) License No. DPR-3 (Docket No. 50-29)

(b) USNRC letter to YAEC, September 16, 1987, NYR 87-173, Inspection No. 50-29/87-07 (c) YAEC letter to USNRC, October 15, 1987 FYR 87-110, reply to reference (b)

Subject:

Steam Generator Surveillance Program Improvements

Dear Sir:

This letter is in response to the request for information resulting from Inspection No. 50-29/87-07 conducted during the period May 11-29, 1987. Reference (b), the inspection report, documents eight proposed improvements to our steam generator surveillance and maintenance programs and requests a description of our plans in this area. Accordingly, Attachment A describes our intentions in the area of each respective proposal.

Your offer of staff support in an effort to deve3op and institute a change to the steam generator surveillance t chnical specifications is greatly appreciated. Yankee personnel will be in contact with your staff in the near future in this regard.

If you have any questions or desire additional information, please contact us.

Sincerely, 1

l YANKEE ATOMIC ELECTRIC COMPANY I /

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L. H. Heider i Vice President / Manager of Operations cc: USNRC Region I USNRC Resident Inspector, YNPS 8801210121 800112 00!

PDR ADOCK 05000029 G PDR If

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y Attachment A i

1. RECOMMENDATION Develop and/or utilize inspection techniques with better capability to characterize the nature and size (axial and circumferential directions) of the flaws being found in the Yankee Rowe S/Gs. For example, follow-up inspections of degraded and defective tubes with a rotating pancake probe and/or examination of tube specimens removed in the field.

YAEC RESPONSE Flaw characterizing equipment such as rotary pancake probes and multi-element (8-1) probes are currently being researched for application during the 1988 refueling outage. Within practical and reasonable limits, Yankee intends to conduct follow-up inspections of degraded and defective tubes to characterize the nature and size of the flaws. We do not intend to remove any tube specimens at this time.

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2. RECOMMENDATION Propose a Technical Specification change to address issues such as full length tube inspection and sample sizes (see Staff Recommendations in NRC Generic Letter 85-02).  ;

YAEC RESPONSE During 1988, Yankee will propose a change to the Technical Specifications governing steam generator surveillance inspection criteria. This proposal will address full length tube inspections and sample sizing.

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3. RECOMMENDATION Develop an inspection technique or plan to assure the tight radius U-bend tubes receive complete inspection coverage.

i Also, consider entry from both sides of a steam generator

. to ensure that tubes in rows 1-6 can be inspected with full

! sized probes on both the hot and cold leg sides (also see l item 8 below).

• l YAEC RESPONSE End-to-end inspection of the tight radius U-bend tubes with ,

i current equipment requires entry from both sides of a steam -

generator. Approximately 90% of the tubes at Yankee can be inspected, full length, from one side. The remaining tight -

! radius tubes can be inspected through one side and over the

U-bend, but not down to the far end. -

l The tight radius U-bend tubes have demonstrated a degradation j rate significantly lower than that of the general population.

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y Therefore, we have some reservations as to whether, from an ALARA standpoint, it is justified to require double entries.

A valid option could be to alternate the point of entry with each inspection outage, inspecting the opposing ends of the tight radius U-bend tubes at one half the frequency of the general population and greatly reducing exposures.

In any case, during the 1988 refueling Yankee will attempt to use a modified SM-10 manipulator (see item 4) which should make entry into both sides of the steam generator reasonable from an ALARA standpoint. Meanwhile, revised sample selection criteria in the 1988 Proposed Change to the Technical Speci-fications (see item 2) will provide a forum to resolve our Concerns.

4. RECOMMENDATION Update ECT manipulator and other steam generator inspection and maintenance equipment to reduce radiation exposures during inspection consistent with ALARA goals (e.g., obtain a modified SM-10 manipulator to fit YNPS S/G and consider use of temporary, lead shields for S/G manways which permit passage of ECT equipment - reference September 1986 INPO report titled "Swedish Experience in Reducing Occupational Radiation Exposure").

YAEC RESPONSE Yankee will procure a modified SM-10 manipulator system for the 1988 refueling and will apply additional shielding, consistent with ALARA practices. The SM-10 has not been used in steam generators as omall as those at Yankee, but, if successful, the modified SM-10 manipulator should provide significant dose reduction to the ECT process.

S. RECOMMENDATION Increase involvement of experienced ECT personnel (i.e.,

Engineering /ISI staff) in assuring quality of the steam generats- inspection program. t YAEC RESPONSE Yankee will utilize experienced ISI/ECT personnel to assure standards of quality in the steam generator inspection program (ECT) comparable to those applied in the ISI program.

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6. RECOMMENDATION Ensure at least a secondary analysis will be completed for future ECT data (reference EPRI guidelines for S/G inspec-

, tions). Also, consider (a) providing independent agency

analysis or 3rd party review of data and (b) perform onsite testing and qualification of analysts prior to performing outage activities.

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4 YAEC RESPONSE Independent primary and secondary analyses will be completed for all future-ECT data. In addition, third petty review will

'be applied to resolve all discrepancies between the primary I and secondary analyses and verify a representative sample, including all indications of 120%.

Per the EPRI guidelines, procedures are being developed which describe primary and secondary analysis and third party review requirements. . The procedures will also describe data analysis characteristics unique to Yankee and will provide for Yankee specific testing and qualification of analysts prior to performing outage activities.

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7. RECOMMENDATION In reports to the commision, trend future data and attempt to quantify the type and location of indications. Trends will include rates of degradation, changes in types, and increases / decreases in total number (s) of affected tubes.

YAEC RESPONSE Future reports to the commision will attempt to quantify the type and location of indications. Data trends, including rates of degradation, changes in types and' total' number (n) of affected tubes will be documented in plant records and made i available to our resident inspector.

I 8. RECOMMENDATION f Review and implement (as appropriate for YNPS) the EPRI Guidelines for Steam Generator Inspections and consider an

• j inspection of all four steam generators at each inspection outage per the EPRI guidelines, j YAEC RESPONSE l The EPRI Guidelines for Steam Generator Inspections is under i review and will serve as a reference document for furthur improvements in the ECT program.

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The inspection of all four steam generators at each inspection outage is described in the EPRI Guidelines as an economic decision. It does not address ALARA concerns nor operating history. We have based our decision on all three. In our i case, a twenty-seven year operating history reflects low j frequency of degradation, consistently slow rates of flaw progression and the virtual elimination of forced outages due i to steam generator tube leakage. Therefore, it is not appropriate at this point for Yankee to inspect all four generators at each inspection outage.

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