ML20099C963

Ro:On 840911,moisture Discovered in Purified Helium Supply Line Wells During Installation of New Moisture Sensing Probes.Tests Indicate Leak Source Is Circulator Penetration A.Rate of Leak Approx .05 Gpm

ML20099C963
Person / Time
Site:	Fort Saint Vrain
Issue date:	10/29/1984
From:	Gahm G, Gahm J PUBLIC SERVICE CO. OF COLORADO
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
P-84418, TAC-59936, NUDOCS 8411200133
Download: ML20099C963 (2)

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public Service Company N CoHolmde f

16805 WCR 19 1/2, Platteville, Colorado 80651

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I October-29, 1984 Fort St. Vrain NOV - 51984 unit i p

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Mr. John T. Collins Regional Administrator U. S. Nuclear Regulatory Commission j

611.Ryan Plaza Drive, Suite 1000 Arlington, TX 76011

SUBJECT:

HELIUM CIRCULATOR INTERSPACE MOISTURE INVESTIGATION

Dear Mr. Hackney:

On September 11, 1984, new moisture sensing probes were installed in all four purified helium supply line wells to the helium circulators' interspaces.

As the installation was being performed moisture was noticed in the supply line wells.

In order to determine the source of water and the leakage rate, a series of tests were performed on September 22, 1984 through September 28, 1984.

The testing involved draining "A"

and "B" circulator interspaces individually with each corresponding helium circulator operating, self turbining and completely isolated from all sources of water.

In order to determine the rate of moisture ingress into each helium circulator interspace, the interspace was drained over a specified period of time yielding a flow rate.

These tests were performed several times to substantiate the results collected on the previous tests.

In addition, a primary seal leak test was conducted on "A" Helium Circulator's interspace. This was accomplished by -placing a water manometer on the moisture element well of the purified helium supply line of "A" Circulator.

The reactor was then depressurized to 24 inches of water vacuum.

There was no vacuum observed in this interspace, indicating that there is not a primary seal leak.

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From' the testingLperformed, it is apparent that'a bearing water !1eak' of approximately 0.05 gpm exists.inf;the "A" Circulatori penetration.

Due'to the inaccessibility of the-piping within*the-penetration under current ' plant conditions,.the location of the leak cannot be-positively.identif.ied.

=However, there are,a number of-fittings and flanges 'in the' bearing.waterispiping, and it is (likely. that the leak

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..ni((; "L affect the circulator's-operability.

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We will be replacing the "A" Circulator during:the present plant

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[J.--W.Gahm Manager Nuclear Production-3 Fort St. Vrain Nuclear Generating Station 1

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