ML19309D924

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Requests Approval of Mod to Improve Heating,Ventilation & Air Conditioning Isolation Sys Based on 760519 RO 50-313/76-07.Design Change to Be Implemented During Jan 1978 Refueling Outage,Upon NRC Approval
ML19309D924
Person / Time
Site: Arkansas Nuclear Entergy icon.png
Issue date: 12/08/1977
From: David Williams
ARKANSAS POWER & LIGHT CO.
To: Desiree Davis
Office of Nuclear Reactor Regulation
References
1-127-7, NUDOCS 8004110749
Download: ML19309D924 (1)


Text

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IE FILE COPY H ELPI N G BUILO ARKANSAS O A AKANS AS POWER & LIGHT COMPANY P O. SCX Sei LITTLE ACCK. AAK ANSAS 722Q3. (5013 371 4000 December 8, 1977 c2- ,

1-127-7 f. 'N

/ ,y Director of Nuclear Reactor Regulation  !?j  ;[p..

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ATIN: Mr. D. K. Davis, Acting Chief 1 -

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Operating Reactor Branch #2 C4 I U. S. Nuclear Regulatory Commission L g gg Washington, D. C. 20555 .

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Subject:

Arkansas Nuclear One-Unit 1 b m

Docket No. 50-313 License No. DPR-51 HVAC Isolation System (File: 1510)

Gentlemen:

In our Reportable Occurrence Report 50-313/76-7 of May 19,1976 we reported the failure of our Unit I as built control system for the Control Room Ventilation System to isolate the control room in 3 seconds as specified in th7 FSAR, Volume IV, page 9.4.9.

s As committed in the subject ROR, we have developed a modification to improve the HVAC isolation system. However, during design development we found the FSAR commitment time of 3 seconds to be unachievable.

The design criteria for our Unit 2 control room HVAC isolation system of 10 seconds from a step input of 0-15 ppm chlorine (Unit 2 FSAR, Volume VI, page 9.4-2) has been reviewed and approved by the Staff (ANO-2 Safety Evaluation Report, Section 9.5.1, page 9-7) . Based upon this approval, we propose to change the Unit 1 criteria to be consistent with that of Unit 2.

By 10CFR50.59 a(2)i, "the consequences of an accident may be increased" -

by this new criteria therefore we feel this change may be an unreviewed safety question and should be approved by you prior to implementation.

Upon your approval, we wish to implement this design change during our i upcoming refueling outage. Since this outage is scheduled for late i January,1978, your most expeditious reply will be appreciated.

Very truly yours, 8004110 7Vf Y&}{.$k h Daniel H. Williams

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