ML20151K179

Provides 120-day Response to GL 97-01, Degradation of Control Rod Drive Mechanism Nozzle & Other Vessel Closure Head Penetrations

ML20151K179
Person / Time
Site:	Seabrook
Issue date:	07/30/1997
From:	Feigenbaum T NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-97-01, GL-97-1, NYN-97089, NUDOCS 9708050359
Download: ML20151K179 (6)

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. . ' j ggsw,,,, i P North North Atlantic Energy Service Corporation P.O. Box 300 j

'fy - Atlantic Seebroet Nii O3874 II (603) 474-9521  :

The Northeast Utilities System i

July 30,1997  ;

i Docket No. 50-443 i NYN-97089  !

i United States Nuclear Regulatory Commission Attention: Document Control Desk {

Washington, DC 20555-0001 Seabrook Station l 120-Day Resnonse to GCaeric Letter 97-01  !

This letter provides North Atlantic Energy Service Corporation's (North Atlantic) 120-day response to Generic Letter (GL) 97-01, " Degradation of Control Rod Drive Mechanism Nozzle And Other Vessel  !

Closure llead Penetrations." The response includes a description of the Seabrook Station program for i ensuring the timely inspection of PWR control rod drive mechanism (CRDM) and other closure head  !

penetrations.

Should you have any questions regarding this response, please contact Mr. Terry L. liarpster, Director of Licensing Sen ices, at (603) 773-7765.

Very truly yours, NORT11 ATLAN WI kkGY SE ICE CORP.

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Ted C. Feigbau Executive Vice Preside and Chief Nuclear Officer ll t l 7

tj s: n n q ru t. s J hD73 4I .j cc: Iluben J. Miller, Region 1 Administrator j Albert W. De Agazio, Sr. Project Manager l F. Paul Bonnett, NRC Senior Resident inspector l

9708050359 970730 ERE -

PDR ADOCK 05000443 P PDR (( h h 'll'h '**BM i j

i 1 0 STATE OF NEW HAMPSHIRE a

l' Rockingham, ss. July 30,1997 i

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Then personally appeared before me, the above-named Bruce L. Drawbridge, Director -

, Services, Nonh Atlantic Energy Service Corporation, that he is duly authorized to execute and file the

, foregoing information in the name aid on the behalf of North Atlantic Energy Service Corporation and i

that the statements therein are true to the best of his knowledge and belief.

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j Susan J. Messehotary Public j- My Commission Expires: December 22,1998 -

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' ENCLOSURE TO NYN-97089 4

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4 Response to USNRC Generic Letter 97-01

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" Degradation of Control Rod Drive Mechanism Nozzle And Other Vessel '

Closure Head Penetrations" l

Introduction

., Generic Letter 97-01 (GL), Degradation of Control Rod Drive Mechanism Nozzle and Other Vessel 1

Closure licad Penetrations, was issued to request licensees to describe their program for ensuring the timely inspection of PWR control rod drive mechanism (CRDM) and other closure head penetrations. This response provides requested information for Seabrook Station.

Prior to the issuance of the GL, Nonh Atlantic panicipated with the Westinghouse Owners Group (WOG),

3 the Electric Power Research Institute (EPRI) and the Nuclear Energy Institute (NEI) to understand the operational experience, identify technical issues, cause factcrs, ielative importance, and solutions related to the CRDM nozzles and other vessel head penetrations (VHP). One of these tasks was the development of safety evaluations that characterized the initiation of damage, propagation and consequences. These safety l evaluations are contained in WCAP 13565 and are applicable to Seabrook Station. The NRC reviewed the i safety evaluations and issued a safety evaluation report (SER) to NEI on November 19,1993. The safety evaluations and the SER establish the basis for Seabrook Station's continued operation.

4 Response to Reauested Information Item 1.1: l "1.1 A description of all inspections of CRDM nozzle and other VHPs performed to the date of this i generic letter, including the results of these inspections.

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, Response:

Visual inspection walkdowns for boric acid are performed in accordance with Generic Letter 88-05 during the beginning of each refueling outage. Prior to plant startup following each refueling outage, a system leakage test and visual examination (VT-2) is conducted on the reactor vessel pressure retaining boundary in accordance with ASME Section XI, Subsection IWB, Examination Category B-P. A surface a

examination (PT) was performed on two peripheral CRDM housings in accordance with ASME Section XI, Subsection IWB, Examination Category B-O on September 19, 1992, during Scabrook Station's i

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second refueling outage.

. These walkdowns and examinations have not identified any boric acid buildup or leakage that would indicate leakage of primary coolant through a cracked reactor vessel head penetration.

l Response to Requested Information Item 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.

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b) Provide the scope for the CRDM nozzle and of the 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.

l 1.3 If a plan has ngt been developed to periodically inspect the CRDM nozzle and other VHPs, pro 5ide the analysis that supports why no augmented inspection is necessary.

1.4 In light of the degradation of CRDM nozzle and other VHPs described above, provide the analysis j that supports the selected course of action as listed in either 1.2 or 1.3, above. In particular, provide a description of all relevant data and/or tests used to develop crack initiation and crack growth models, the methods and data used to validate these models, the plant-specific inputs to these models, and how these models substantiate the susceptibility evaluation. Also, if an )

integrated it.dustry inspection program is being relied on, provide a detailed description of this program."

Response: North Atlantic is a participant in the WOG/NEI Reactor Pressure Vessel (RPV) head penetration integrated inspection program. This integrated program includes volumetric inspections of head penetrations that have been performed and additional volumetric inspections that will be performed.

Presently, the integrated industry inspection program proposes inspections of two Combustion Engineering design plants and two Babcox & Wiler,x design plants over the next three years. Westinghouse design plants are likely to be included in the intrgrated industry inspection efforts within the next few months.

North Atlantic believes that the number of plants that have been or will be inspected is sufficient to demonstrate the adequacy of the WOG/NEI integrated inspection program. The need and schedule for re-inspection will be based on an evaluation of the inspection results from the WOG/NEI integrated inspection 1

program. The plant performing re-inspections will keep the NRC staffinformed ofits future re-inspection plans.

WCAP 14901 " Background and Methodology for Evaluation of Reactor Vessel Closure Head Penetration Integrity for the Westinghouse Owners Group" provides the information relative to items 1.2,1.3, and 1.4.

Sections 1.2 and 1.3 of WCAP 14901 contain the historical data on inspections performed to date.

Sections 2.0 through 4.0 provide a description of the models used in performing the evaluations. WCAP 14901 will be submitted separately by the WOG.

In addition to the WOG integrated inspection program, the three PWR owners groups, the Electric Power j Research Institute, and the Nuclear Energy Institute are cooperatively working to compile information on  !

the estimated operating time from January 1,1997, needed to initiate and propagate a crack 75% through I wall in a vessel penetration. This information will be evaluated to determine if an adequate number of l

plants performed inspections or are planning to perform inspections. This evaluation will be completed by the end of 1997 and provided to the NRC by the WOG.

Response to Reauested Information item 2:

"2 Provide a description of any resin bead intrusions, as described in IN 96-11, that have e; cceded the current EPRI PWR Primary Water Chemistry Guidelines recommendation for primary water sulfate levels, including the following information:

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2.1 Were the intrusions cation, anion, mixed bed? l 2.2 What were the durations of these intrusions? )

2.3. Does the plant's RCS water chemistry Technical Specifications follow the EPRI guidelines?

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2.4 Identify any RCS chemistry excursions that exceed the plant administrative limits for the following species: sulfates, chlorides or fluorides, oxygen, boron, and lithium. Identify any conductivity excursions which may be indicative of resin intrusions. Provide a technical assessment of each excursion and any follow-up actions.

2.5 Provide an assessment of the potential for any of these intrusions to result in a significant increase in the probability for IGA of VHPs and any associated plan for inspections."

Response: North Atlantic has reviewed the Seabrook Station records 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 Seabrook Station. This data search was structured to identify all resin intrusion events into the primary coolant system with a magnitude grer.ter than I ft' (30 liters). The threshold of I ft' was chosen as a conservative lower bound since it represents less than 15% of the estimated volume of resin released into  ;

the reactor coolant system during the two events at Jose Cabrera.  !

l Routine analysis for sulfate in reactor coolant was performed for plant operation since August 19,1990. A sulfate concentration in the range of 15 to 17 ppm peak concentration was used as the indicator of cation resin ingress. This concentration is approximately equivalent to a volume of I ft'. This corresponds to an j clevation of a 28 micro S/cm increment in specific conductance. i Had either specific conductance or sulfate increases indicated resin ingress to the magnitude of the threshold quantity identified above, additional data evaluation would have been conducted to look for a corresponding depression in pH or elevation in lithium as corroborating information of the incident. In the case of the use of sulfate data as the indicator, specific condactance would also have been included as ,

confirmatory data had a significant in leakage event been identified.

There is no evidence of a cation, anion, or mixed bed resin intrusion in the reactor coolant system for the period reviewed. Similarly, there were no indications of resin intrusion into the reactor coolant system based on a review of specific conductivity data for the review period.

Reviews for boron, chlorides, fluorides and oxygen are not considered necessary because these species are not viewed as valid indicators of cation resin ingress and degradation within the primary coolant system of a PWR. Borate, chloride, and fluoride anions could be associated with the anion portion of mixed bed resin (cation plus anion); however, if mixed bed resin leakage to the RCS had occurred, the cation portion of the resin would contain the sulfate indicator described above. Detectable dissolved oxygen in reactor coolant during power operation, with appropriate hydrogen overpressare on the volume control tank and specified l residual dissolved hydrogen in the reactor coolant, was not postulated to occur and therefore, could not be associated with resin inleakage.

Notwithstanding, no RCS cxcursions that exceeded administrative limits were observed for the period for boron, sulfates, chlorides and fluorides. Minor lithium transgressions have occurred during plant operation that exceeded administrative limits however, were not determined to be attributed to resin intrusion.

On one occasion, RCS oxygen was measured above limits during a plant heatup following Refueling Outage 2. The limit was exceeded while in Mode 5 and was the result of placing an air-saturated mixed bed demineralizer in service after the reactor coolant system had been deoxygenated. The RCS temperature at the time of discovery was approxir-ately 185 F. This event did not occur as a result of resin intrusion.

Seabrook Station has followed the EPRI PWR Primary Water Chemistry Guidelines since commercial operation on August 19,1990 and has implemented revisions when issued.

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