ML20141H616

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Provides 120-day Response to GL 97-01, Degradation of Control Rod Drive Mechanism Nozzle & Other Vessel Closure Head Penetrations. Util Will Implements Wog/Nei Integrated Insp Programs,Which Will Include Listed Items
ML20141H616
Person / Time
Site: Wolf Creek Wolf Creek Nuclear Operating Corporation icon.png
Issue date: 07/24/1997
From: Muench R
WOLF CREEK NUCLEAR OPERATING CORP.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ET-97-0085, ET-97-85, GL-97-01, GL-97-1, NUDOCS 9707310255
Download: ML20141H616 (5)
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Text

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WfSLF CREEK NUCLEAR OPERATING CORPORATION Richard A. Muench Vice President Engineering l

l July 24, 1997 j l

ET 97-0085 l U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station Pl-137

. Washington, D. C. 20555 l

i

Subject:

Docket No. 50-482: 120 Day Response to Generic l Letter 97-01, " Degradation of Control Rod Drive 4

Mechanism Nozzle and Other Vessel Closure Head Penetrations" Gentlemen:

Generic Letter 97-01, " Degradation of Control Rod Drive Mechanism Nozzle and Other Vessel Closure Head Penetrations," requested licensees to describe their

. program for insuring the timely inspection of pressurized water reactor control rod drive mechanism (CRDM) and other closure head penetrations. The attachment provides Wolf Creek Nuclear Operating Corporation's (WCNOC) 120 day a response to Generic Letter 97-01.

WCNOC activities are anticipated to implement the Westinghouse Owners Group / Nuclear Energy Institute integrated inspection programs. These future actions include:

  • Developing an industry histogram that groups plants without names based on the time to initiate and propagate a crack to 75% through wall 9
  • Developing an industry activity timeline/ schedule. j Results of these activities will be provided to the NRC by January 5, 1998.

If you should have any questions regarding this submittal, please contact me at (316) 354-8831, extension 4034, or Mr. Richard D. Flannigan at extension 4500.

. i Very truly yours,

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s I 9707310255 970724 PDR

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ADOCK 05000482 ^

P PDR Richa d A. Muench Q)hb RAM /jad "al'

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  • Gs 7J Atta ch'nent cc: W. D.~ Johnson (NRC), w/a E. W. Merschoff(NRC), w/a J. F. Ringwald (NRC), w/a J. C. Stone (NRC), w/a hllfllh.h.lhlh.lh.lhll e . .

PO. Box 411/ Burhngton, KS 66839 < Phone: (316) 364-8831 An Ewal opgntundy Employer M F HUVET j

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i STATE OF KANSAS )

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' Richard A'. Muench, of. lawful age, being first duly sworn upon oath-says that he,is Vice President Engineering of Wolf Creek-Nuclear Operating Corporation; that he has read the foregoing document and knows the content thereof; that i he has' executed that same'for and on behalf of said Corporation with full

. power and authority to do so; and that the facts therein stated are true and 1

. correct to the best of his knowledge, information and belief.

By M Richardg.Muench Vice President

. Engineering ,

1 SUBSCRIBED and sworn to before me this h day of U /f , 1997, i

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. JUUE A. DALE NotaryPubic yof Kpness A Appt Empires /0/9 0/97 . jg y .

Expiration Date -

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Attachment to ET 97-0085

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Electric Power Research Institute and the Nuclear Energy Institute (NEI) to better understand the operational experience, identify technical issues and cause factors, and to determine relative importance and solutions for this concern. One of these tasks undertaken was the development of safety evaluations that characterized the initiation of damage, propagation, and consequences. These safety evaluations are containad in WCAP 135652 and are applicable to Wolf Creek Generating Station (WCGS). The NRC reviewed the safety eval  : ions and issued a safety evaluation report (SER) to NEI on November 19, 1993. The safety evaluations and the SER establish the basis for continued operation of WCGS.

Information Requested -- Item 1 through 1.1

1. Regarding inspection activities:

1.1 A description of all inspections of CRDM nozzle and other VHPs performed to the date of this generic letter, including the results of these inspections

Response

Generic Letter 88-05 vessel head inspections are performed at the commencement of a refueling outage and at the discretion of plant management following a plant trip subsequent to a long full power operating period. These inspections have identified boron deposits from leaks associated with the mechanical seals, not cracked head penetrations.

ASME Section XI examinations inclule a visual examination, VT-2, of all accessible penetration welds at the completion of each refueling outage and a ,

surfare examination, PT, of 10% of ;he peripheral control rod drive housing i penet: ition welds once every ten year inspection interval. Although these ;

examinations do not include the Alloy 600 portions of the head penetration, l they do provide examination information on the head penetrations. To date, no indications have been reported.

There have been no replication inspections or plant specific volumetric inspections performed at WCGS.

A summary of this information compiled for WOG plants is contained in Section 1.3 of WCAP 149012 .

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WCAP-13565, Rev. 1, " Alloy 600 Reactor Vessel Adapter Tube Cracking Safety Evaluation," February 1993 (Proprietary) 2 WCAP-14901, Rev. O, " Background and Methodology for Evaluation of Reactor Vessel Closure Head Penetration Integrity for the Westinghouse owners Group,"

July 1997 (Proprietary)

Attechment to ET 97-0085

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  • Page 2 of 3

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Information Requested -- Items 1.2 through 1.4 1.2 If a plan has been developed to periodically inspect the CRDM nozzle and other VHPs:

a. Provide the schedule for first, and subsequent, inspections of the CRDM nozzle and other VHPs, including the technical basis for this schedule.
b. Provide the scope for the CRDM nozzle and other VHP inspections, including the total number of penetrations (and how many will be inspected) , which penetrations have thermal sleeves, which are spares, and which are instrument or other penetrations.

1.3 If a plan has not been developed to periodically inspect the CRDM nozzle and other VHPs, provide the analysis that supports why no augmented inspection is necessary.

l 1.4 In light of the degradation of CRDM nozzle and other VHPs described above, provide the analysis that supports the selected course of action l as listed in either 1.2 or 1.3, above. In particular, provida a description of all relevant data and/or tests used to develop crack initiation and crack growth models, the methods and data used to i validate these models, the plan t-specific inputs to these models, and how these models substantiate the susceptibility evalua tion. Also, if an integrated industry inspection program is being relied on, provide a l detailed description of this program. '

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Response

i WCNOC is a participant in the Westinghouse Owners Group /NEI RPV head i penetration integrated inspection program. This integrated program includes i volumetric inspection of head penetrations that have been performed (See WCAP 14901, Section 1) and additional volumetric inspections that will be performed. Present plans call for two CE-design plants and two B&W - design plants to be inspected over the next three years. Additional Westinghouse -

design plants are likely to be addeC to the list over the next few months, as an integrated industry inspection plan is formulated.

WCNOC believes that the number of plants that have or will be inspected is sufficient to demonstrate the adequacy of the WOG/NEI integrated inspections j reogram. <

The need and schedule for re-inspection will be based on an evaluation of the l inspection results from the integrated inspection program. The plant performing re-inspections will keep the NRC staff informed of its future re-  !

inspection plans.

Information Requested -- Item 2

2. Provide a description of any resin bead intrusions, as described in IN 96-11, that have exceeded the current EPRI PWR Primary Water Chem istry Guidelines recommendations for primary water sulfate levels, in.al uding the following information:

2.1 Were the intrusions cation, anion, or mixed bed?

2.2 What were the durations of these intrusions?

M Attachment to ET 97-0085 1 . . . * ' Page 3 of 3 l

1 2.3 Does the plant's RCS water chemistry Technical Specifica tions follow the EPRI guidelines?

2.4 Identify any RCS chemistry excursions that exceed the plant  ;

adminis tra tive limits for the following species: sulfates, chlorides or fluorides, oxygen, baron, and lithium, f

2.5 Identify any conductivity excursions which may be indicative of l resin intrusions. Provide a technical assessment of each excursion a and any followup actions.

1 2.6 Provide an assessment of the potential for any of these intrusions l to result in a significant increase in the probability for IGA of V'iPs and any associated plan for inspections.

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) Response:

2. WCGS has performed a historical review to determine if any incident of .

resin ingress similar to those which occurred in 1980 and 1981 at the  !

Jose Cabrera (Zorita) plant has occurred at Wolf Creek Generating l Station (WCGS). This review was structured to identify any resin intrusion events into the primary coolant system that were of a magnitude greater than one cubic foot (30 liters). The threshold of one cubic foot was chosen as a conservative lower bound since it represents i less than 15% of the estimated volume of resin released into the reactor co w.nt system during the two events at Jose Cabrera. This review determined that WCGS has no evidence of resin bead intrusions.

1 2.1 No intrusions were identified. Therefore, a 2esponse is not l applicable.

l 2.2 No intrusions were identified. The afore, a ?esponse is not applicable.

2.3 WCGS RCS chemistry limits that were previously addressed in Technical Specifications have been relocated to Chapter 16 of the Updated Safety Analysis Report. This includes sampling frequencies for Dissolved Oxygen, Chlorides and Fluoric es . With the exception of the suspended solids analysis, the WCGS Chemistry sampling frequencies and limits are at least equal to, if not more restrictive than EPRI guidelines.

2.4 As discussed and defined during a telephone conference call with Mr. C. E. Carpenter, NRC Lead Project Manager, on April 21, 1997, WCNOC investigated excursions as being significant, abnormal, unexpected events. Based on this definition WCGS has experienced no sulfate, chloride, fluoride, oxygen, boron, or lithium ,

excursions from startup to present.  !

2.5 WCGS has experienced no conductivity excursions. RCS conductivity is currently compared to theoretical conductivity 5 times per week. This provides a mechanism for quick and easy identification of excursions.

2.C No intrusions were identified. Therefore, a response is not applicable.

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