ML19273B556

Submits Basis for Tech Specs Which Will Limit Purging to 90-h Per Year.Util Still Investigating Justification for Unlimited Purging & May Submit Tech Spec Change Request at Later Date.Class III Amend Fee Encl

ML19273B556
Person / Time
Site:	Arkansas Nuclear
Issue date:	04/02/1979
From:	Cavanaugh W ARKANSAS POWER & LIGHT CO.
To:	Reid R Office of Nuclear Reactor Regulation
References
1-049-2, 1-49-2, NUDOCS 7904090166
Download: ML19273B556 (5)

Text

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ARKANSAS POWER & LIGHT COMPANY POST OFFICE BOX 551 UTTLE ROCK. ARKANSAS 72203 (501)371-4422 April 2, 1979 WILLIAM CAVANAUGH 111 vce president Generaton G Constncton 1-049-2 Director of Nuclear Reactor Regulation ATTN: Mr. R. W. Reid, Chief Operating Reactor Branch #4 U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Subject:

Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. DPR-51 Reactor Building Purging During Operation (File: 1510, 1511.1)

Gentlemen:

Your letter of November 29, 1978, related concerns relative to potential failures of purge penetration valves which could lead to a degradation in containment integrity, and requested either:

(1) A proposed Technical Specification which requires that there be no purging during operation, or (2) A schedule for proposing a Technical Specification which will limit purging to 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per year and justification by test or by test and analysis, or (3) A schedule for justification of unlimited purging.

Our letter of January 30, 1979 stated that we expected to complete and submit Option (2) above by April 1,1979. We are herein submitting a Technical Specification which will limit purging to ninety hours per year and our bases. However, we are investigating justification for unlimited purging and may submit a Technical Specification change request to that effect at a later date.

The bases for purging the reactor building ninety hours per year is as follows.

The subject valve operators were sized analytically to seat and unseat the valve with a differential pressure of 59 psi and were shop tested to the manufacturer's procedure and were witnessed. The actual closing time at zero t.P was less than five seconds for all valves installed in the ANO-1 purge system.

7 9 0 4 0 9 01(;ro MEMBEA MiDOLE COUTH UTILITIES SYSTEM

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Mr. R. W. Reid April 3, 1979 The fluidynamic characteristics of Butterfly valves tend to produce operating torques that will close the valve. If the fluidynamic effects were to be added to the operating tests, the va'.ve may actually close in a shorter time than those in the static test. References for this phenomenon may be found in "A Contribution to the Study of Butterfly Valves" by D. Gaden from Water Power, December, 1951, and

" Torque and Cavitation Characteristics of Butterfly Valves" by Turgut Sarpkaya, Paper #60-WA-105 from transactions of the ASME Journal of applied mechanics.

We wish to point out that even though our valves are sized to close against 59 psi, our accident analyses indicate that valve closure would actuate immediately on high reactor building pressure (4 psig) and that the valves would complete closure and isolation prior to the building pressure reaching 30 psig. We believe this margin is adequate for an operator of this size. This, combined with the unlikely occurrence of a LOCA during the allowed ninety hours of purging, substantiates a more than adequate margin of safety for ninety hours of purging per year.

Further, during our four years of operating experience, we have encountered no problems with the purge valves or operators. We have not, in the past, used the purge system for reducing reactor building atmosphere activity during normal operation. Our procedures do allow this, however, prior to personnel entry during power operation, if necessary. To date, we have used our purge system only to reduce the atmosphere activity and temperature prior to shutdown. This facilitates personnel entry and reduces costly down time. With these considerations and the above related justifications, we request your timely approval of the attached Technical Specifications.

Pursuant to 10 CFR 170.22, we have determined this request to involve a single safety issue and, therefore, is a Class III amendment requiring a $4000 remittance. A check for that amount is enclosed.

Very truly yours,

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William Cavanaugh III J WC: ERG:lg Enclosure

STATE OF ARVAfiSAS )

) SS COUtiTY OF PULASKI )

William Cavanaugh III, being duly sworn, states that he is Vice President, Generation & Construction, for Arkansas Power & Light Company; that he is authorized on the part of said Company to sign and file with the fluclear Regulatory Commission this Supplementary Infonnation; that he has reviewed or caused to have reviewed all of the statements contained in such information, and that all such statements made and matters set forth therein are true and correct to the best of his knowledge, informa-tion and belief.

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William Ca p h 111

,L m 4 SUBSCRIBED AfiD SWORfi T0 before me, a Notary Public in and for the County and State above named, this L . _ day of k 1979.

t. C flotary Public My Conmission Expires:

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• 79A-5 3.22 REACTOR BUILDING PURGE VALVES APPLICABILITY This specification applies to the reactor building purge supply and exhaust isolation valves.

OBJECTIVE To specify maximun time limits for reactor building purging during normal plant operation.

SPECIFICATION 3.22.1 The reactor building purge supply and exhaust isclation valves shall be concurrently open not more than 90 heurs per calander year when reactor building integrity is required.

3.22.2 Af ter reaching the limit of Specification 3.22.1,

a. The reactoc building purge supply and exhaust isolation valves shall be closed.

b. With one reactor building purge supply and/or one exhaust isolation valve open, close the open valve (s) within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or be in cold shutdown within the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

c. With both reactor building purge supply and/or both exhaust isolation valves open, close the open valves within I hour or be in at least hot standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in cold shut-down within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

CASES The reactor building supply and exhaust isolation valves are required to be closed during normal plant operation in order to ensure reactor building integrity. Purging is allowed approximately 1*o of each year to allow control of the reactor building environment prior to personnel access during shutdown.

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4.25 REACTOR BUILDING PURGE VALVES APPLICABILITY This specification applies to the reactor building purge supply and exhaust isolation valves.

OBJECTIVE To assure reactor building integrity.

SPEC IF ICATIO_ N_

4.25.1 The reactor building purge supply and exhaust isolation valves shall be determined closed:

a. At least once per 31 days, and

b. Within one hour following completion of a purging operation.

4.25.2 Prior to each purging operation, verify that the planned period of purging will not contribute to exceeding the limit of Specification 3.22.1.

BASES Determination of reactor building purge valve closure will ensure that reactor building integrity is not' unintentionally breeched and excessive quantities of radioactive materials released via the reactor building purge system.

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