ML19319E474
| ML19319E474 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/03/1975 |
| From: | Cavanaugh W ARKANSAS POWER & LIGHT CO. |
| To: | Howard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| Shared Package | |
| ML19319E475 | List: |
| References | |
| NUDOCS 8004110586 | |
| Download: ML19319E474 (1) | |
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September 3, 1975
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s Mr. E. Morris Howard, Director
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U. S. Nuclear Regulatory Commission 61'1 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76012
Subject:
Arkansas Power G Light Company Arkansas Nuclear One-Unit 1 1
Docket No. 50-313 License No. DPR-51 Unusual Event Report No. 50-313/75-2A I
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Dear Mr. Howard:
Attached find a copy of the subject follow-up report to Mr. B. C. Rusche, Director, Office of Nuclear Reactor Regulation, concerning that unusual event reported on June 25, 1975 (Unusual Event Report No. 50-313/75-2).
'Ihis report is provided for your. information and use pursuant to the requirements of Technical Specification 6.12.3.2.
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Very truly youts T
JLc William Cavanaugh ILI
- I Manager, Nuclear Services 1
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Unusual Event Report No. 50-313/75-2A 2.
1:eport Date:
August 29, 1975 3.
Occurrence D;i t e :
May 8, 1975 4
Facility:
Arkansas Nuclear One-Unit i Russellville, Arkansas 5.
Identification of Occurrenec:
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 llot Standby Net Output M%c Cold Shutdown Percent cf i;ull Power Refucling Shutdown Load Ch; int;es ! uring Rout ine Rotatine Startup Operation l'.u: iec Shutdown Uperation Other (specify)
NA DUPMCATE DOCUMENT En re n
sys em n er ANO 7.
Description of Occurrenec:
of pages.
See Unusual Event Report No. 50-313/75-2.
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March 4, 1975 NSP-10, Rev. 2 Page 2 of 4
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Unusual Event Report No. 50-313/75-2A 8.
Designation of Apparent Cause of Occurrenec:
Design'~
X Procedure Fbnufacture Unusual Service Condi tion Including Environmental Installation /
Construction Component Failurc Operator Other (specify) 9.
Analysis of Occurrence:
The hydraulic performance of the RBS system has been re-analy:ed to check the B6N-results presented in UER 50-313/75-2. The situation was 2
analy:cd following a LOCA -(5 ft break DBA case per Figure 14-61 of the FSAR) for the one and two spray pump operating conditions.
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The B6f analysis was identical except a 14.1 ft2 4
LOCA was assumed.
The size of our DBA is 5 ft2, which is a conservative figure. Also, the 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 diffe'rence in size of the opening does not affect the time required for draining the tanks; The re-analysis used viscositics for the hydroxide and thiosulfate solutions determined by laboratory tests of solutions duplicating the storage tank concentrations. This is the main discrepancy between B6W's 8
and our results.
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.conditio.n, 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 BGW's analysis as presented in UER 50-313/75-2.
The shorter times calculated by re-analysis results in shorter exposure of the containment paints to pil Icycis in the 10 to 11 range. The paints have been tested' to 9.5 pil in Franklin Jnstitute DBA qualifica-tion testing. Therefore, the higher pil of the spray for such short times is not considered in any way detrimental to the paints.
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Fb reh 4, l')75 NSP-10, Rev. 2 Page 3 Of 4
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50-313/75-2A
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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 j
exposed to high pII for a short period of time and the thyroid dose increases are very small.
Based un these results, no corrective action is deemed necessary.
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