ML20099M063

Responds to Eg Adensam Re License Condition 20, Internal Corrosion Protection for Fuel Oil Storage Tanks. Internal Tank Coating Unnecessary.Uncoated Tanks Will Provide Adequate Diesel Generator Fuel Oil Supply

ML20099M063
Person / Time
Site:	Catawba
Issue date:	11/21/1984
From:	Tucker H DUKE POWER CO.
To:	Adensam E, Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 8412030217
Download: ML20099M063 (3)

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i DUKE POWER GOMPANY P.O. HOx 33180 CHAMLOTTE. N.C. 28242 HAL H. TUCKER TELEPHONE vu,a pasamese (704) 373-4538

( mm. m mm. November 21, 1984 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation

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U. S. Nuclear Regulatory Commission

( Washington, D. C. 20555 Attention: Ms. E. G. Adensam, Chief Licensing Branch No. 4 Re: Catawba Nuclear Station l Docket Nos. 50-413 and 50-414

Dear Mr. Denton:

License Condition 20, Internal Corrosion Protection for Fuel Oil Storage Tanks, i which is included in the preliminary draft of Facility Operating License NPF-31 for Catawba Unit 1, would require the application of an internal corrosion protection to the fuel oil storage tanks prior to startup following the first refueling outage or the submittal of justification for not coating the tanks.

4 The following discussion summarizes Duke Power Company's position that an internal tank coating is not necessary. Also included is a response to Ms. Elinor G. Adensam's letter of November 7, 1984.

System Description

The diesel fuel oil system at Catwba includes four 45,000 gal. storage tanks ,

per unit or 2 tanks per diesel. The tanks are fabricated from 3/8 inch nominal thickness carbon steel which includes a 1/32 inch corrosion allowance. Each tank is approximately 12 feet in diameter and buried under approximately 5 feet of backfill and a concrete pad. The Unit i fuel oil tanks were coated with motor oil following sand blasting and were filled with fuel oil in March 1980.

A recirculation and purificatior system takes suction from the flush mounted sample connection on the bottom of the tank and discharges the fuel oil at a rate of 25 gpm through a simplex filter (25 micron particle removal rating). The supply lines to the day tank are connected by an outlet raised 6 inches above the bottom of the tank.

No Regulatory Basis for Internal Tank Coating As discussed in Section 9.5.4.2 of the Catawba SER, the Staff concluded that

" Internal corrosion protection,for the fuel oil storage tanks, as required l by Section 7.5 of ANSI Std N195, is not being provided". Section 7.5 of 1 ANSI N195 states, " Protection against internal and external corrosion shall -)

be provided." On March 24, 1982 Washington Public Power Supply System I requested an interpretation of this section by Mr. F. A. Dougherty, Chairman h

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1 Mr. Harold R. Denton, Director November 21, 1984 Page Two ANS 59.51. By an unanimous vote of the committee, an internal corrosion allowance was deemed to meet the requirements of Section 7.5. Therefore.

ANSI N195 was not an appropriate basis for requiring an internal tank coating. It is our opinion that, contrary to Mr. Denton's April 28, 1982 Office Letter No. 2, Revision 2 that stated that " Staff reviewers should not decrease nor go beyond the scope and requirements of any specific SRP section", the Staff's requirement for an internal tank coating went beyond the requirements of the Standard Review Plan (NUREG-0800).

No Identified Problem with Uncoated Tanks The position taken by the Staff in the Catawba SER was based on an unsupported interpretation of ANSI N195, not on plant operating experience. At no time i during the review process has the Staff identified any occurance of a problem with uncoated, buried fuel oil storage tanks. On the contrary, internally 4

coated fuel oil tanks at the Hanford N-Reactor and at Limerick (See INPO SER 2-84) have experienced problems with flaking and peeling of the coating.

Therefore License Condition 20 would not enhance plant safety but may instead degrade plant safety.

Duke has had over 40 years experience with uncoated, buried fuel oil tanks at the Company's fossil and nuclear stations. Our experience with these tanks is testimony to the reliability of uncoated tanks. Inspections of buried tanks at the Lee, Cliffside, Allen and Marshall Steam Stations have shown that internal corrosion is not a problem with buried fuel oil tanks. The survey of local industries which was documented in my letter of October 2, 1984 further supports this conclusion, i Justification for not Internally Coating Catawba Tanks As a result of the continuing controversy over License Condition 20, a special inspection was performed on a 27,000 gallon underground fuel oil tank at Duke's Lee Steam Station. Details of this inspection were transmitted by my letter of October 2, 1984. After 34 years of service, minimal deterioration of the tank was noted. An ultrasonic inspection was made of the tank walls. Reductions in the mean tank wall thickness were noted at the top, bottom and sides of the tank of 0.0017, 0.0072, and 0.0002 inches, respectively. Based on the greater reduction noted in the bottom of the tank, a 1/32 inch corrosion allowance would be exceeded in an additional 113 years of service at the present corrosion rate.

j It should be noted that the Lee fuel oil tank did not have the benefit of design j and operating features to minimize corrosion such as

1) Cathodic protection

2) Fuel oil sampling to limit amount of water in new fuel l 3) Tank maintained nearly full

4) Periodic (10 year) tank cleaning l

The results of the Lee tank inspection provides reasonabic assurance that the Catawba fuel oil tanks will perform their intended function without the application i of an internal coating. As noted in previous submittals, the Catawba fuel oil tanks 1

have additional design and operating features to further minimize tank corrosion i

Mr. Harold R. Denten. Dir ctsr November 21, 1984 l Page Three l

1) Cathodic protection (fully operable 6/85 for Unit 1)

2) Use of high quality. fuel

3) Tanks maintained nearly full in accordance with the Technical Specifications

" 4) Periodic (Quarterly) drainage of accumulated water from the bottom of the tank

5) Periodic (10 year) tank cleaning In order to provide further assurance that corrosion of the buried fuel oil storage tanks at Catawba is not progressing at a faster rate than expected, measurements of the tank wall thickness will be performed in conjunction with each 10 year cleaning. The measurement of the tank wall by ultrasonic or other means will include sufficient points to determine a statistical mean thickness. The resulting data will be evaluated and abnormal degradation (corrosion allowance exceeded) would be reported to the NRC pursuant to 10 CFR 50.73. In addition to the inspections during the 10 year cleaning, J

the Catawba Unit 2 tanks will be inspected prior to fuel load. .

Conclusion Based on the above discussions, it is concluded that License Condition 20 has been satisfied in that an internal tank coating is not necessary and there is reasonable assurance that the uncoated tanks will provide an adequate diesel generator fuel oil supply.

Very truly yours,

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Hal B. Tucker ROS: sib cc: Mr. James P. O'Reilly, Regional Administrator Mr. Jesse L. Riley U. S. Nuclear Regulatory Commission Carolina Enviromental Study Group Region II 854 Henley Place 101 Marietta Street, NW, Suite 2900 Charlotte, North Carolina 28207 ,

Atlanta, Georgia 30323 l Robert Guild, Esq. NRC Resident Inspector P. O. Box 12097 Catawba Nuclear Station Charleston, South Carolina 29412 <

Palmetto Alliance 2135 Devine Street Columbia, South Carolina 29205

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