ML19345C781

Responds to NRC 800613 Ltr Re Exceptions to IE Bulletins 79-05,79-05A & 79-05B, Nuclear Incident at Tmi. Cold Shutdown Defined & Method Clarified.Manual Trip on Loss of Offsite Power Is Unnecessary

ML19345C781
Person / Time
Site:	Arkansas Nuclear
Issue date:	11/28/1980
From:	Trimble D ARKANSAS POWER & LIGHT CO.
To:	Novak T Office of Nuclear Reactor Regulation
Shared Package
ML19345C782	List: ML19345C781 ML19345C785
References
1-110-28, IEB-79-05, IEB-79-05A, IEB-79-05B, IEB-79-5, IEB-79-5A, IEB-79-5B, NUDOCS 8012080342
Download: ML19345C781 (2)

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'e ARKANSAS POWER & LIGHT COMPANY POST OFFICE BOX 551 UTTLE ROCK, ARKANSAS 72203 (501)371-4000 November 28, 1980 1-110-28 Mr. Thomas M. Novak Assistant Director for Operating Reactors Division of Licensing U. S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Arkansas Nuclear One-Unit 1 Docket No. 50-313 micense No. DPR-51 Exceptions to IE Bulletin 79-05 (File: 1510.1,1510.3)

Gentlemen:

In accordance with your letter of June 13, 1980, the following is provided.

1) In addressing the case of one flow path being inoperable, the licensee's use of the term " cold shutdown" does not make it clear that the licensee is not relying on the SG for cooling.

Response

Cold shutdo a is defined, per the ANO-1 Technical Specifications, as the condition whereby the re ctor is subcritical by as least 1% A 'K/k and t is no more than 200 F. With a primary side temperature less av9 than or equal to 2000F, heat cannot be removed by the steam generators as the secondary side water would not boil.

2) Also, in the above case, the licensee does not conform to the Bulletin position that the cooldown shall be accomplished in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> because the licensee's comitment is qualified by a statement "12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> or at the maximum safe. rate".

Response

The AN0-1 emergency feedwater (EFW) syster consists, in part, of two  ;

EFW pumps. One pump is motor-driven r.hile the other is steam-driven. l IC/' If the flowpath containing the motor-driven pump is the one which is

$33:/,E3jf9ii."' inoperable, a cold shutdown condition may not be attainable until l

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this path is returned to operable. This occurs because main steam is I used to drive the steam-driven pump. Therefore, the qualifying state- '

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"or at the maximum safe rate" would allow us the time necessary q to place a motor-driven pump in service. ,

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Mr. Thomas M. Novak November 28, 1980

3) The-licensee's procedures states that if both of the EFW pumps and the AFW pump are inoperable, the reactor will not be shutdown but rather, power will be reduced to less than 5% using the main feed-water pumps and maintained there until one of the EFW pumps or- the AFW pump' is made operable. Following that, the reactor will be placed in cold shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> or at the maximum safe rate.

Response

Because the main feedwater pumps (MFWP's) are turbine driven by main

. steam, cold shutdown cannot be achieved using only the MFWP's. It is, therefore, necessary to ha've in service either the motor-driven EFW pump or the motor-driven AFW pump in order to achieve cold shut-

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down.

With regard to Item 10 of IE Bulletin 79-05A, our response dated April 16, 1979 states "ANO-1 Technical Specifications require that prior to initiating

. maintenance on safety-related components, the redundant component be demon-strated operable." AP&L believes, therefore, that we are in compliance with the bulletin requirements.

With regard to Item 4 of IE Bulletin 79-05B, we maintain our position that a manual trip on loss of offsite power is unnecessary. Furthermore, this manual trip would result in a reduction in the margin of safety. The unit is designed to runback to approximately 15% power. Initiating a manual trip would cause a loss of this potential power source and thus a reduction in the margin of safety. As stated in your evaluation, this runback is diffi-

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cult to achieve. However, the consequence of not achieving the runback i<.

a turbine _ trip, and thus a reactor trip.

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Very truly yours, l ~

7,, David C. Trimble Manager, Licensing DCT: MAS:pw

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