U-602780, Informs of Current Status of Efforts Re Condition of Protective Coatings in Primary Containment & Drywell in Response to Confirmatory Action Ltr

Informs of Current Status of Efforts Re Condition of Protective Coatings in Primary Containment & Drywell in Response to Confirmatory Action Ltr

ML20149K809
Person / Time
Site:	Clinton
Issue date:	07/02/1997
From:	Romberg W ILLINOIS POWER CO.
To:	Beach A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
CAL, U-602780, NUDOCS 9707300167
Download: ML20149K809 (3)

Text

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U-602780 i 4F.190 i July 2, 1997 ]

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Docket No. 50-461 i

j. Mr. A. Bill Beach j Regional Administrator

. RegionIII !Tl dl.14 A!0

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U.S. Nuclear Regulatory Commission l

l'UBLIC DOCUMENT h6 , t 801 Warrenville Road

Lisle, Illinois 60532-4351  ;

Subject:

Interim Response to June 9,1997 Confirmatory

Action Letter Regarding the Condition of Protective {

Coatinas in the Primary Containment and Drywell  ;

Dear Mr. Beach:

I In our recent letter (U-602761, dated June 12,1997) regarding the condition of

. protective coatings in the primary containment and drywell at Clinton Power Station i (CPS), Illinois Power (IP) committed to provide the results of our protective coatings removal activities and the coatings testing program. This letter is submitted to inform you of the current status of our efforts in this area.

As described in our initial response to the subject Confirmatory Action Letter -

(CAL), we are removing protective coatings in the primary containment and drywell found to be loosely adhered, chipping, peeling, or blistering. This activity is nearly complete. This activity was originally scheduled to finish on June 28,1997. However, as described in our initial response to the subject CAL, we indicated that the program scope may be expanded based on the results of walkdowns that were occurring coincident with the removal activities. During the course of the extensive coatings removal efforts, CPS personnel identified two areas needing protective coating removal that were not initially believed to be problematic. These areas are the coatings on the reactor recirculation (RR) pump motors, as well as a small area located at the center and top of the primary containment liner. There are significant personnel hazards associated with accessing these areas (e.g., high dose areas near the RR pump motors, and M extensive work necessary to safely design and erect a scaffolding system near the top of g the dome), and therefore the planning for and removal of the protective coatings in 0 these two remaining areas is still in progress. These two removal activities will be

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complete prior to startup.

N ' lllRIEllllIIIRER i 9707300167 970702 PDR ADOCK 05000461- i^

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The protective coating testing plan described in our previous letter (U-602761, l dated June 12,1997) regarding the subject CAL has been completed. The objective of the 1

! test plan was to validate that visually acceptable coatings in the primary containment and l

{ drywell at CPS have sufficient adhesion to confirm they will not separate from the I substrate during and after a design basis accident. The number of test sites was selected to i

encompass various areas of the primary containment and drywell, different substrates

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within those areas, and various coating conditions. To support the objective of the test plan, sites were selected from areas that were visually acceptable, areas adjacent to

! degraded coatings, and areas that have been repaired.

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The adhesion testing method used in this program employed small dumbbell-  ;

i. shaped pieces of metal known as a " dollies". These dollies were applied to the coating surface to be tested using an adhesive. After the adhesive cured, the dollies were

! subjected to a tensile force until separation occurred, and the results were recorded. The protective coating testing plan used more than 34 test sites throughout the primary containment and drywell. Five dollies were applied at each test site. A typical test site 2

j was an area of approximately 10 ft that was uniform in appearance and had the same coating system applied over the entire test site. Other test sites spanned areas that were  :

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previously repaired or areas that had some degraded coatings removed.

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{ The applicable testing standard (Article 6.4 of ANSI N5.12) states that four out of  !

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five test specimens shall sustain a pull of at least 200 lb. All test sites met this criteria

[0 except two. One of these sites (3G-1) had two dollies pull off at 150 lb., when corrected i for tolerance of the test instrument. Inspection of the dollies showed that these failures

! were due to a failure of the adhesive used to apply the dollies to the coating. As required 1 by the CPS coating testing plan, two additional dollies were placed within four inches of  ;

j the failures and retested. The results of the retesting were acceptable. <

f i The other test site (7B-1) also had two adhesion test pulls in which the dollies 1-were pulled off at 150 lb. after correcting for tolerance of the test instrument. Inspection of these dollies showed that these failures were due to 100% cohesive failure of the inorganic zinc prime coat. This site (7B-1) was one of two sites located at weldments to l the primary containment liner plate. The other similarly located site passed the adhesion criterion. As required by the CPS coating testing plan, five additional dollies were placed I within close proximity of the failed dollies and retested. The results of the retesting were  !

acceptable. To gain additional confidence that the failure at test site 7B-1 was an isolated l case, three additional sites were selected at weldments to the primary containment lir.r plate. These three additional sites all passed the adhesion criterion. Based on the ve:

favorable results of the CPS coating testing plan, we have preliminarily concluded that the qualified coating systems remaining in the primary containment and drywell still meet the qualification requirements of Regulatory Guide 1.54.

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As noted in our previous letter (U-602761) we will be fonvarding a copy of our final detailed evaluation of the condition of the protective coatings in the primary containment and drywell as soon as it is completed. We will continue to be available to meet with you and your staff to discuss the status of our efforts, and the results as they j become available.

Sincerely, l [k &'/ " 19 /b Wayne D. Romberg Assistant Vice President JFK/krk cc: NRC Clinton Licensing Project Manager

NRC Resident Office, V-690

NRC Document Control Desk Illinois Department of Nuclear Safety a

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