ML19262B983

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Responds to NRC 791214 Ltr Requesting Info Re Control Room Toxic Gas protection.Redundant,quick-acting Chlorine Detectors Presently in Control Room Fresh Air Inlet
ML19262B983
Person / Time
Site: Arkansas Nuclear Entergy icon.png
Issue date: 01/10/1980
From: Trimble D
ARKANSAS POWER & LIGHT CO.
To: Reid R
Office of Nuclear Reactor Regulation
References
1-010-08, 1-10-8, NUDOCS 8001220376
Download: ML19262B983 (2)


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ARKANSAS POWER & LIGHT COMPANY POST OFFICE BOX 551 LITTLE ROCK. ARKANSAS 72203 C5C ) 371-4000 January 10, 1980 1-010-08 Director of Nuclear Reactor Regulation Attention: 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 Control Room Toxic Gas Protection (File: 3600, 1510)

Gentlemen:

In response to your letter on this subject dated December 14, 1979, which requests chlorine detectors, automatic isolation and a reduction of the control room isolation air exchange rate, the following is provided:

1) Request:

Install quick-response chlorine detectors in the fresh air inlets.

Response

Redundant, quick acting chlorine detectors are prescatly in place in the. control room fresh air inlet.

2) Request:

Isolate control room automatically on high chlorine alarm within ten (10) seconds. This is the time interval between the chlorine concentration exceeding 5 ppm at the isolation dampers and the time the dampers are completely closed.

1785 193 8001220 3 76 fV'E MDE A MC1E ECUTH UTILITiE S SYS*E *."

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1-010-08

, Mr. R. W. Reid January 10, 1980

Response

The chlorine detectors' signals initiate automatic isolation of the ANO 16 2 common control room and provide an audible alarm in both sections of the control room in case of high chlorine gas concentration. The detectors are able to detect and signal a step increase in chlorine concentration of 0 to 15 ppm within 5 seconds (based on 66% response). Control room isolation is accomplished within 5 seconds after detector trip. These detectors are described in Section 9.4.1.1.2 of the ANO-2 FSAR, and the design criteria described in this response has been reviewed and approved by the Staff (ANO-2 Safety Evaluation Report, Section 9.5.1, page 9-7). Based on this approval, we propose that the ANO-1 criteria be consistent with that of ANO-2.

3) Request:

The control room isolation air exchange rate should be re-duced from 3 to 0.06 air changes per hour.

Response

In the event of high chlorine, the combined ANO-16 2 control rooms are isolated from both outside air and adjacent rooms.

The control room emergency air filtration system is based on a minimum of three (3) room air changes per hour for the combined control room volume. A higher recirculation rate of fifteen (15) air changes per hour is provided by the emergency air conditioning system. This system is described in the ANO-2 FSAR, Section 9.4.1, and has been reviewed and approved by the Staff (ANO-2 SER Section 9.5.1, page 9-7) . Based on this approval, we propose that the ANO-1 criteria be consistent with that of ANO-2.

Very truly yours,

.0we2 C. "LdA David C. Trimble Manager, Licensing DCT: ERG:bj m 1785 194'

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