ML19319E387
| ML19319E387 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 06/25/1975 |
| From: | ARKANSAS POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML19319E377 | List: |
| References | |
| NUDOCS 8004100676 | |
| Download: ML19319E387 (3) | |
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, 1.
Unusual Event Renort No.
50-313/75-2 2.
Report Date:
June 25,1975 3.
Occurrence Date:
May 8, 1975 4.
Facility:
Arkansas Nuclear One-Unit 1 Russ:.11ville, 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 FMe Co'ld Shutdo'wn Percent of Full Power Refueling Shutdown Load Changes During Routine i
Power Operation Routine Startup y
Operation
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Routine Shutdown Operation Other (specify)
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7.
Description of Occurrence:
1 Analysis by Babcock 6 Wilcox of the hydraulic performance of the RBS under accident conditions reveals that the Sodium Thiosulfate and Sodium Hydroxide Tanks may not draw down uniformly with the Borated Water
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Storage Tank.
It was, however, noted by B5W that this analysis was sensitive.to the as-built piping configuration.
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UnusualEventR[ ct No. 50-313/75-2 8.
Designation of Apparent Cause of Occurrence:
Design X
Procedure Manufacture Unusual Service Condition
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Including Environmental Installation /
Construction Component Failure Operator Other (specify)
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9.
Analysis of Occurrence:
The hydraulic performance of a RBS was analyzed following a LOCA (14.1 ft )
2 in the hot leg of the RCS. The situation was analyzed for the one and two header case (i.e., 1 and 2 LPI pumps, 1 and 2 HPI pumps, and I and 2 RBS pumps). The hydraulic results for the piping system show that:
1.
The Sodium Hydroxide and Sodium Thiosulfate tanks emptied before the i
Borated Water Storage Tank (BNST). Thus, there is no thiosulfate or hydroxide in the RBS from the time the two chemical tanks empty until the pump suction is switched to the RB sump (recirculation period). The time periods during which the RBS does not have thio sulfate or hydroxide is conservatively estimated to be as long as 21 minutes.
f 2.
For the two header case, the pH of the spray solution is between 10 and 11 for up to 1300 seconds (=22 minutes).
For the one header case, precise pH valves are not available, but the estimated pII's seem to be slightly higher (a few tenths of a pH unit) than the tvo header case and the high pH condition seems to last about twice as long.
l l
Analysis.of thyroid dose increase as a result of_ no chemical additives in the, spray for this period resulted in very little effect.
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j Unusual Event Report No. 50-313/75-2 4
10.
Corrective Action:
Arkansas Power 6 Light Company is reevaluating.the hydraulic study of Babcock 6 Wilcox and performing our own calculations. These results should be ready for submittal to the Commission by August 15, 1975.
Arkansas Power 6 Light Company has also notified all paint vendors to determine if those paints in the Reactor Building are compatible with a pH range of 11 to 12 (a conservative range) for short periods of time (up to 45 minutes).
Preliminary investigations of Babcock 6 Wilcox indicate that a short duration exposure in this range will not damage the coating systems. The results of APSL's investigation will be.
reported to the Commission at the same time as hydraulic results are submitted.
Based on these results, further corrective action will be proposed and implemented if necessary.
11.
Failure Data:
NA 4-G 8
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