ML20195H037
| ML20195H037 | |
| Person / Time | |
|---|---|
| Site: | 07000824 |
| Issue date: | 11/11/1988 |
| From: | Olsen A BABCOCK & WILCOX CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 24931, NUDOCS 8811300195 | |
| Download: ML20195H037 (3) | |
Text
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Subject:
Report of Pool Water Leacage License:
SNM-778, Docket 70-824 Gentlemen:
On the meening of October 13, 1988, it was discovered that water had leaked from the Transfer Canal and Storage Pool.
It is not clear at this time that a report is required under the provisions of 10 CFR 20, Section 20.405(a)(iii) for this occurrence.
However, the occurrence was reported by telephone to Region II and NRC Headquarters and it is our practice to follow a verbal report with a written one.
Facility Dascription The Transfer Canal and Storage Pool (Pool) is a "T"
shaped concrete pool tha t is used for the storage and handling of highly radioactive materials and components.
The Pool is located in the Cask Handling Area within Building B.
The Transfer Canal portion of the Pool is 6-feet wide, 43.5-feet long, and 24-feet deep.
It extends from a water-tight gate on the north end, to the south wall under Hot Cell No.1.
The Storage Pool is a 10-foot by 10-foot off-set section or the west side of the Transfer Canal.
It is 23-feet deep.
The total capacity of the Pool is approximtely 57,000 gallons. The two sections of the l
Pool are equipped with overflow gutters that are piped to a holding l
tank that is located in the Primry Equipnent Cell, which is a below l
grade room located to the north of the Cask Handling Area.
The l
gutters are pre-cast concrete structures that are mortared in place l
and mortared to one another.
The lip of the gutters are approximtely l
3 inches below the floor level of the Cask Handling Area and are 4 I
inches deep.
Occurrence The Pool is norm 11y operated with a water level from 4 to 18 inches below the lip of the gutters. On the af ternoon October 12, 1988, the Pool was inadvertently filled to the lip of the gutters. The following morning, October 13, the pool level was found to have decreased to about 4 inches below the lip of the gutters.
The norm 1 evaporative loss rate is approximtely 0.5 inch in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Approximtely 515 gallons of water was lost from the pool.
Observations of the pool level showed that the leakage had stopped on the morning of October 13.
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The pool level was drained down to 6-inches to prevent any further leakage that may have resulted if the pool leakage was continuing at an imperceptibly slow rate.
i Subsequent investigation revealed that Pool water had leaked through cracks in the gutter seams, into the gutters and thence into the gutter drain lines.
The gutter orain lines leaked the water onto the soil beneath the floor of the Cask Handling Area.
The leakage continued until the pool level reached 4-inches, which is the lower seam of the gutters.
Little if any of the water reached thr holding tank in the Primary Equipment Cell.
A sample of the pool water was taker on the morning of October 13, and analyzed for gamma emitting radionuclides.
It was found that 748 microcuries of gamma emitting radionuclides could have been released to the restricted area.
The major contributing isotopes are Manganese
-54, Cobalt-60, Cesium-134 & 137 An additional 64 microcuries of non-garra emitting radionuclides was estima ted from pool scaling factors.
Using the 10 CFR 20, Appendf x 8. Table I, Column 2. values, the MPC fraction for the total release is 1.55.
There was no evidence that this activity has reached the boundary of the restricted area.
Water samples taken from ground water monitoring wells located within the restricted area indicated no increased activity.
Corrective Action i
The drain lines from the gutter have been temporarily plunged.
This l
will prevent further leakage to the soil.
Permanent plugging will be performed when it is determined that further investigation is unnec-t cessary or nonproductive.
A steel sump will be constructed and installed on the pool wall at a level that will prevent the Pool water level from exceeding 4 inches.
Excess water will flew into this sump.
i An electric motor-driven pump will take a suction from this sump and pump the water to the holding tank in the Primary Equipment Cell. All plumbing will be above the floor in the Cask Handling Area.
The pump i
motor will be conhected to the emergency power bus.
Routine testing of the pump will be established when it is installed.
Personnel were not exposed to radiation or radioactive materials in 1
excess of any regulatory limit as a result of this occurrence.
The area of the leak is near the center of Building B and migration of the contamination is unlikely.
The location of the contamination will be entered in our recoros for use when decommissioning is planned at the l
end of plant life.
No further action regarding the occurrence is l
planned at this time.
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Very truly yours, BABC0CK & WILCOX a McDermott company l
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Arne F. Olsen Senior License Administrator l
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U. S. Nuclear Regulatory Commission 101 Marietta Street, NW l
Suite 2900 l
Atlanta, GA 30323
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