ML19319E401
| ML19319E401 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 08/29/1975 |
| From: | ARKANSAS POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML19319E395 | List: |
| References | |
| NUDOCS 8004100687 | |
| Download: ML19319E401 (3) | |
Text
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Unssual Ever. Report No. S0-313/7S-2A 2.
Report Date:
August 29, 197S 3.
Occurrence Date:
May 8, 197S 4.
Facility:
Arkansas Nuclear One-Unit 1 Russellville, Arkansas S.
Identification of Occurrence:
Reactor Building Spray (RBS) system may'not draw down uniformly as stated' in the FSAR.
6.
Conditions Prior to Occurrence:
. Steady-State Power Reactor Power MWth
-Hot Standby Net Output MWe
' Cold Shutdown; Percent of Full Power Refueling Shutdown Load Changes During Rout ~inc Power Operation p)
Routinc Startup t, d Operation
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Routine Shutdown Operation
.0ther (specify)
NA 7.
Description of Occurrence:
See Unusual Event Report No. S0-313/7S-2.
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Unusual Event Rr~Mrt No. 50-313/75-2A v
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Designation of Apparent Cause of Occurrenco:
I Design X
Procedure Manufacture Unusual S'ervice Coitdition Including Environmental Installation /
Construction Component Failure Operator Other (specify) 9.
Analysis of Occurrence:
. The hydraulic performance of the RBS system has been re-analyzed to check the B6W results presented in UER 50-313/75-2. The situation was analyzed following a LOCA (5 ft2 break DBA case per Figure 14-61 of the
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' FSAR) for the one and two spray pump operating conditions.
The B5W analysis was identical except a 14.1 ft2 LOCA was assumed.
The
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g size of our DBA is 5 ft, which is a conservative figure. Also, the y'~)
system drain rate is at full capacity with either the 5 ft2 or 14.1 ft2 break as the tanks drain by gravity flow. Therefore, the difference-in size of the opening does not affect the time required for draining the tanks.
The re-analysis used viscosities for the hydroxide and thiosulfate solutions determined by laboratory tests of solutions duplicating the storage tank concentrations. This is the main discrepancy between B5W's '
and our results.
i Re-analysis found the time between depletion of the chemical tanks and depletion of the Borated Water Storage Tank (BWST) is 15 minutes for the-one spray pump operating condition, and. 6 minutes 25 seconds for the two spray pump operating condition. These conditions both include five minutes for operator action to switch to recirculation mode. These figures are significantly less than BSW's analysis as presented in UER 50-313/75-2.
The shorter times calculated b'y re-analysis results in shorter exposure of the containment paints to pH levels in the 10 to 11 range. The paints have been tested to 9.5 pH in' Franklin Institute DBA qualifica-tion testing. Therefore, the higher pH.of the spray for such short times is not considered in any way detrimental to the paints.
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Unusual. Events Re ":t No.
50-313/75-2A j
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Corrective Action:
The results of the analysis indicate that no significant problems are created by the uneven draining of the sodium hydroxide, sodium thio-sulfate, and borated water storage tanks. The containment paints are exposed to high pH for a short period of. time and the thyroid dose increases are very small.
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Based on these results, no corrective action is deemed necessary.
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Failure Data:
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Narch 4, 1975
.NSP-10, Rev. 2 Page 4 of 4 e
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