ML17252A848

Letter Regarding a February 1, 1974 Occurrence Where Both Door of the 80 Foot Elevation Personnel Air Lock to the Containment Building Were Inadvertently Open at the Same Time for a Period of About Thirty Seconds - Indian Point Unit. 2

ML17252A848
Person / Time
Site:	Indian Point
Issue date:	02/19/1974
From:	Cobean W Con Edison, Consolidated Edison Co of New York
To:	O'Leary J US Atomic Energy Commission (AEC)
References
Download: ML17252A848 (2)

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'*""7'..1 Ed~

Consolidated Edison Company of New York, Inc.

4 Irving Place, New York, NY 10003 I

February 19, 1974 Re:

Indian Point Unit No. 2 Facility Operating License DPR-26 AEC Docket No. 50-247 A.0.-4-2-7 Mr. John F. O'Leary, Director Directorate of Licensing Off ice of Regulations U. S.:Atomic Energy Commission Washi~gton, D. C.

20545

Dear Mr. O'Leary:

The following report is provided pursuant to the requirements of Section 6.12.2(a) of the Technical Specifications to Facility Operating.License No. DPR-26.

On February 1, 1974, at approximately 3:50 P.M., both doors of the 80 foot elevation personnel air lock to the contain-ment building were inadvertently open at the same time for a period of about thirty seconds.

At time of the occurrence, the reactor was shutdown with all full length control rods fully inserted in the core.

The reactor coolant system pres-sure and temperature were 2235 psig and 5400F respectively and the reactor coolant boric acid concentration was approxi-mately 1190 ppm boron.

With this concentration of boron and a11 control rods fully inserted~ the reactor was subcritical by more than 7 percent delta k/k.

Our investigation into the cause of the above occurrence re-vealed the following pertinent information:

Whenever the plant is not in the cold shutdown condition, and containment entry is to be made by other than operating per-sonnel, a man who has been properly instructed on the oper-ation of the air lock doors and the requirements for contain-ment integrity is stationed in the air lock to pperate its controls.

In addition, signs are posted at the outside of each door to inform plant personnel when system conditions are such that containment integrity is required.

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Mr.*. John F. O'Leary

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F~bruary 19, 1974 Re:

Indian Point Unit No. 2 Facility Operating License DPR-26 AEC Docket No. 50-247 A.0.-4-2-7 At about 3:50 P.M. on February 1, 1974, an offsite Company employee in attempting to enter containment from outside the air lock mistakenly operated the wrong hand wheel open-ing the inner lock door.

Both the operator stationed in-side the air lock and the person outside realized what happened and both started to close the inner door.

Upon closing, the inner door bounced off its seating frame and the door latch rotated into position with the inner door still open.

When the individual outside the air lock noted the erroneous indication that the inner door was closed, he immediately started opening the outer door.

Before the op-erator inside the air lock could stop its movement, and re-close the door, containment integrity had been breached for about thirty seconds.

The measures previously taken to minimize the chance of malfunc-tion of the door interlock will continue to be followed.('refer to my letter to you of September 27, 1973).. In addition/**we are working with Wedco and the manufacturer of the air lock to deter-mine the cause of the interlock malfunction and necessary correc-tive action.

As previously indicated, at the time of the occurrence, the re-actor was in a shutdown condition.

While in the shutdown condition, the consequences of major accidents are significantly reducied.

This fact combined with the shortness of the duration of the lack of con-tainment integrity minimize the safety*implications to this occur-rence *.

Very truly yours,.

\\

Warren R. Cobean, Jr., Man Nuclear Power Generation cc:

Mr. James P. O'Reilly