ML20217J497

Requests Addl Info Re Results of Util Most Recent Steam Generator Insp at ANO-2 & Util Methodology Used to Predict Future Performance of SG Tubes

ML20217J497
Person / Time
Site:	Arkansas Nuclear
Issue date:	10/18/1999
From:	Nolan M NRC (Affiliation Not Assigned)
To:	Hutchinson C ENTERGY OPERATIONS, INC.
References
TAC-MA1951, NUDOCS 9910250092
Download: ML20217J497 (3)

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UNI (ED STATES

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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. enana anni g gy

+ . October 18, 1999 Mr. C. Rardy liutchinson -

Vice President, Operations ANO

Entergy Operations, Inc.

w 1448 S. R. 333 -

Russellville, AR 72801 .

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING THE OPERATIONAL' ASSESSMENT FOR STEAM GENERATOR TUBING FOR CYCLE 14 - ARKANSAS NUCLEAR ONE, UNIT NO. 2 (TAC NO. MA1951)

Dear Mr. Hutchinson:

- During the review of your submittal dated June 2,1999 (2CAN069901), documenting the operationa'l assessment _of steam generator tubing for Cycle 14 operation for Arkansas Nuclear One, Unit No. 2 (ANO-2), we identified several areas of your submittal that required further clarification. The following is a list of questions regarding the results of your most recent steam generator inspection at ANO 2 and your methodology used to predict future performance of the steam generator tubes.

1.  : During the ANO-2 Cycle 13 refueling outage (2R13 outage), in-situ testing determined

' that an axial crack at an eggerate failed to meet the 3 dP pressure criteria for steam gene _rator tube R85L67.- Entergy has indicated that this resulted from a previous inspection that failed to requife the tube to be removed from service because a

. resolution analyst dispositioned the indication as acceptable without requiring a rotating pancake coil (RPC) inspection. Entergy has asser1ed that the new process of inspecting with RPC all indications called by.either production analyst will resolve this problem.

This assertion makes the assumption that the failure to meet the 3 dP pressure criteria (i.e., three times the normal operating pressure between the primary and secondary side of the steam generator) was due to a missed indication and not due to a higher than

. expecied crack growth rate. Please explain why you believe a high growth rate was not the dominant contributor to the fe4ure to satisfy the 3 dP pressure criteria.

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2. - Please discuss the cra::k growth rate and the crack growth rate evaluation methodology used to addre.ss the operational period between the 1998 mid-cycle outage (2P98) and

. the 1999 spring refueling outage (2R13) for steam generator tube R85L67.

3. . In the discussion of " Sizing and Growth Rate Evaluation," on page 12 of the ANO-2 D !

operational assessment submitted to the staff, Entergy states the following: " Detected results from the 2R13 inspection were compared to the projected operational assessment results and were conservative' relativ!

t The growth rates that were documented following 2R12 are still reasonable and bound l

the current conditions." j Please describe the comparison, for both size and number of flaws, between the

< projected and measured restf ts from the steam generator inspections conducted during the 2R13 refueling outage. Explain if the " projected operational assessment" referred to 9910250072 991018 I

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iC. R. Hutchinson -2. October 1.8, 1999 l

1above was performed prior to 2R13 r with the benefit _of hindsight. Summarize the -

growth rates that were evaluated in 2R13 and how they were determined to be bound by the 2R12 growth rate distribution. '

. 4.' - Pisase indicate the maximum allowable length of an operational period for ANO-2 that .,

would result assuming the probability of 0.95 that the most limiting axial indication will l not exceed the structurallimit, evaluated at a 95 percent confidence level. If you cannot )

p'r ovide this information with a 95 percent enfidence level, then the use of the l I

. confidence level discussed in question N( s is acceptable. The purpose of this

_ question is to obtain an understanding of the sensitivity of probabilty with respect to outage timing.

5. During the June 28,1999, meeting et NRC headquarters, you discussed a "3 dP probability of burst of 9.2 x 102" at n..d-cycle for axial flaws (i.e., a probability of about 0.9 that the tubes will not exceed the structural limit). Please discuss the statistical confidence level of this value, and explain the methodology used to determine this value. If this information cannot be provided, please describe the characteristics of this methodology that preclude this discussion.

The need to provide justification to support the requested changes and the agreement of the ANO staff to comply with this request was discussed with members of your staff during a telephone call on October 8,1999. Based on that telephone call, our understanding is that this

' information can be supplied within a few weeks. A mutually agreed upon due date of l l

Nove'mber 5,.1999, was established for questions 1 - 4. A due date of December 10,1999,  !

was established for question 5 as you indicated that the. answer to this question could take l L -some addition work to develop. These dates were established through discussions with l l John Dosa of your staff.

l Sincerely, ORIGINAL SIGNED BY M. Christopher Nolan, Project Manager, Section 1 Project Directorate IV & Decommissioning Division of Licensing Project Management Office r) Nuclear Reactor Regulation

- Docket No' 50-368

. DISTRIBUTION:

Docket File K. Brockman, RIV

- cc: See next page PUBLIC S. Black PD4-1 r/f OGC

'ACRS To receive a copy of Inis document, indicate "C" in the box ,

OFFICE - PDIV-1/PM ,

C PDIV-1/LA C EMCB/SC ,

PDIV-1/SC C NAME CNolan:dbP L. Berry h ESullivan 6kR.GramrM DATE 4: / /6 /99 10 / ( 4 /9 9 19 /1L /99 9 / d /99 3

4 , 's-

I Arkansas Nuclear One l

cc:

l Executive Vice President Vice President, Operations Support 1

& Chief Operating Officer Entergy Operations, Inc.

Entergy Operations, Inc. P. O. Box 31995

, P. O. Box 31995 Jackson, MS 39286-1995 l Jackson, MS 39286-1995 Wise, Carter, Child & Caraway

! Director, Division of Radiation P. O. Box 651 Control and Emergency Management Jackson, MS 39205 Arkansas Department of Health 4815 West Markham Street, Slot 30 Little Rock, AR 72205-3867 Winston & Strawn 1400 L Street, N.W.

Washington, DC 20005-3502 l

Manager, Rockville Nuclear Licensing l Framatone Technologies 1700 Rockville Pike, Suite 525 Rockville, MD 20852 Senior Resident inspector U.S. Nuclear Regulatory Commission P. O. Box 310 London, AR 72847 l

Regional Administrator, Region IV l U.S. Nuclear Regulatory Commission l 611 Ryan Plaza Drive, Suite 400 i . Arlington, TX 76011-8064 County Judge of Pope County l Pope County Courthouse l Russellville, AR 72801 i

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May 1999 j I