ML19331B917

Affidavit in Support of Motion for Summary Disposition of Tx Pirg Contention A-34.No Basis for Requiring Design to Withstand Hydrogen Expolsions Due to Presence of Criteria That Limit Hydrogen Concentrations Below Flammable Limit

ML19331B917
Person / Time
Site:	Allens Creek File:Houston Lighting and Power Company icon.png
Issue date:	08/06/1980
From:	Fields M Office of Nuclear Reactor Regulation
To:
Shared Package
ML19331B836	List: ML19331B835 ML19331B873 ML19331B875 ML19331B884 ML19331B888 ML19331B894 ML19331B917
References
ISSUANCES-CP, NUDOCS 8008130528
Download: ML19331B917 (4)

Text

O UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD

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In the Matter of HOUSTON LIGHTING & POWER COMPANY

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Docket No. 50-466 (Allens Creek Nuclear Generating Station, Unit 1)

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AFFIDAVIT OF M. B. FIELDS CONCERNING CONTENTION TP A-34 My name is M. B. Fields.

I am employed by the Nuclear Regulatory Canmission as a Containment Systems Engineer in the Containment Systems Branch. My qualifications are listed on the attached qualification sheet.

The purpose of my affidavit is to address TEXPIRG Contention A-34, which reads as follows:

i i-TEXPIRG contends that the Applicant monitoring of in containment building events during LOCA or similar events is not adequate to detect immediately the occurrences of hydrogen explosions. That the recent Three Mile Island incident shows that current approved containment building monitoring apparatus did not bring such an event to the attention of operators immediately, and that there-fore the strong possibility existed that actions which would prevent a second hydrogen explosion were not taken.

There is danger that hydrogen explosions will endanger TEXPIRG members because the containment building during a LOCA is likely to con-tain radioactive gases which would be released from the build'n damaged even lightly by the explosion and in excess of 40 Ci <.g10 l

or 10 CFR 20.

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. Intervenors contend that the hydrogen monitoring system to be installed at ACNGS will not be adequate to detect immediately the occurrence of hydrogen explosions.

The intent of hydrogen monitoring systems is not to detect hydrogen explosions, but rather to provide sufficient infomation to the operators of the plant so that they can maintain the concentration of hydro-gen inside the containment below the flammability limit by judicious use of the hydrogen recombiners.

The Intervenors state that the hydrogen monitoring system used at TMI-2 was inadequate to prevent the hydrogen burn that took pla'ce, and therefore, the hydrogen monitoring system for ACNGS is also inadequate.

The hydrogen control system that will be installed at ACNGS is significantly different in design than the system used at TMI-2 and consists of the following components and subsystems:

1.

The ACNGS hydrogen monitoring system will be actuated from the control room shortly after an accident and will provide a continuous recording of the containment hydrogen concentration for the operators use in the control room. An alam will actuate if the hydrogen analyzer detects a -

hydrogen concentration of 3.0 volume percent. The hydrogen monitoring system is described in Section 6.2.5.2.2 of the PSAR.

To obtain the hydrogen concentration inside the containment at TMI-2, personnel had to go to the sample room and manually open a line, draw a sample of the containment atmosphere into a container, take the container to another l

area, and insert the contents of the canister into a gas analyzer.

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....... 2.

The ACNGS hydrogen monitoring system will have the ability to take samples from eight different points inside the drywell and containment.

These points were selected to provide complete coverage of the drywell and containment. The system consists of two identical analyzer trains, each powered from a different emergency bus, and each having the ability to monitor any of the eight sampling points.

The locations of the eight sampling points are shown in Fig. 7.5.9a of the ACNGS PSAR.

3.

A Drywell Containment Hydrogen Mixing System will be activated so that hydrogen in the drywell will be dispersed throughout the containment volume (PSAR Sections 6.2.5.2.1 and 6.2.5.2.3).

4 4.

A thennal recombiner system will be used to remove hydrogen when con-centration in the containment approaches four percent. Two redundant recombiners are pennanently installed inside the contairrnent (PSAR Section6.2.5.2.4). The recombiners are operable simply by remotely energizing heater elements.

Circulation through the recombiners is by natural convection.

5.

A Containment Hydrogen Purge Subsystem is provided as a further backup to the redundant thermal recombiner system.

In view of (1) the capability of the hydrogen control system to monitor and control hydrogen concentrations throughout containment, including the drywell,

e (2) the mixing' capability, (3) the redundant thennal recombiners and (4) the backup purge system, the Staff's position is that there is no basis for requiring a design to withstand " hydrogen explosions" including additional capability to detect explosions. The ACNGS has a hydrogen control system with a design criteria to limit hydrogen concentrations to less than 4%,

which is below the flammable limit and well below explosive limits (approxi-I mately 18%).

It is the Staff's opinion that the ACNGS hydrogen monitoring system will provide the operators with immediate and sufficient infonnation on the hydrogen concentration inside containment to prevent a flamable mix-ture and an explosive mixture from occurring.

I prepared the foregoing affidavit and swear that it is true and correct to the best of my knowledge, information and belief.

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M.~B. Fields i

Subscribed and sworn to before me this 6th day of August.1980.

h.

M Mit Notary /Public

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My Commission expires:

July 1, 1982 l

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