ML19345G120
| ML19345G120 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 04/05/1974 |
| From: | Searls F PACIFIC GAS & ELECTRIC CO. |
| To: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 3050, RO-DPR-7-74-1, NUDOCS 8103020603 | |
| Download: ML19345G120 (2) | |
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Docket No. 50-133 Vi, 1.:i d V Cf
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Dear Mr. Skovholt:
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This report is submitted in accordance with the require-ments of Section IX.H.2.a(4) of the Technical Specifications of License No. DPR-7.
Notification of this occurrence was made via phone to the office of the Director of the Region V Regulatory Operations Office on the day of the occurrence.
Report Number:
DPR-7 / 74-1 Report Date:
4/5/74 Occurrence Date: 3/27/74 Facility:
Humboldt Bay Power Plant Unit No. 3, Eureka, California Identification of occurrence: A condition occurred which potentially could have impaired the proper performance of the liquid poison injection system.
Conditions Prior to Occurrence: The Unit was operating at a steady state power level of 153 MWt, 47 NWe and 1090 psig reactor pressure.
Description of Occurrence: At 0950, while collecting the semi-annual liquid poison sample, it was observed that the sample did not flow properly until the poison injection equalizing valve (cv4025) was tapped several times.
(See Figure 33, page 69, of the Final Safety Analysis Report). The valve had been exercised several times prior to the sample collection per Operational Testing Procedure No. 9 - Liquid Poison System, Part II - Sampling Procedure. Tapping the valve apparently seated the valve, permitting proper flow.
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8/o3ccao&o3 P00R ORIGINAL
l' Mr. Donald J. Skovholt 2
4/5/74 plant management was notified immediately and the decision was made to recheck the equalizing valve for proper operation.
The equalizing valve was retested at 1055 hours0.0122 days <br />0.293 hours <br />0.00174 weeks <br />4.014275e-4 months <br /> and the sample flow checked to verify that the valve was operating properly, which it was.
Approximately four hours later at 1505 hours0.0174 days <br />0.418 hours <br />0.00249 weeks <br />5.726525e-4 months <br />, another successful test was conducted.
Designation of Apparent Cause of Occurrence: Since the valve stroked properly during the initial valve exercising prior to sample collection, it is believed that the valve's failure to close with proper seating was due to a foreign particle on the valve seat or plug. Tapping the valve body apparently dislodged the particle allowing the valve to seat.
This valve is normally exposed to a nitrogen atmosphere; how-ever, since the piping system is carbon steel, there is potential for contact with pipe scale.
Analysis of Occurrence: Had poison injection been required during the period when the equalizing valve was not properly seated, it would have been possible to inject the poison tank contents into the reactor. The only effect of this occurrence would have been to increase the time required for the injection of poison tank contents.
Corrective Action: The equalizing valve seating problem was corrected immediately when the valve body was tapped. In addition, two follow-up tests were conducted the day of the occurrence to check the proper operation of the equalizing valve by collecting additional samples. Also, the equalizing line was blown to atmos-phere to clear the line of any foreign material.
It is planned that additional valve exercising and sample collecting will be done once a week for a month. If the results indicate that no problem exists, then the valve exercising and sample collecting program will be conducted once a month.
In addition, the valve will i
I be disassembled and inspected during our next refueling outage.
Failure Data: This is the first malfunction involving this valve, which is a Black Sivalls & Byrson Model 70-18-1B DRT 3/4" air operated globe valve with a 1/2" port.
Very truly yours, NLS:PACam cc:
Mr. R. H. Engelken, Director Directorate of Regulatory Operations i
U. S. Atomic Energy Commission l
P00R BRIGINAL