ML20009C758
| ML20009C758 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 07/10/1981 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Cavanaugh W LOUISIANA POWER & LIGHT CO. |
| References | |
| NUDOCS 8107210446 | |
| Download: ML20009C758 (2) | |
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Docket No. 50-313 NSIC s d D <4 c>ff ORB #4 Rdg na""""'
3 L-Mr. William Cavanaugh, III IE-3 Il-JUL 13 gggF 4
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Senior Vice President ACRS-10 l
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Er. orgy Supply JStolz Arkansas Power & Light Company GVissing 7'D, /7*T 6
P. O. Box 551 RIngram Little Rock, Arkansas 72203 Gray File a
EBlackwood
Dear Mr. Cavanaugh:
H0rnstein This is to confirm the recent telephone conversation between Mr. Larry Young AP&L, and Mr. Guy Vissing, NRC, concerning the Baron Dilution 4
Event for Arkansas Nuclear One, Unit No.1.
As a result of a reanalysis W the Boron Dilution Event for hot and cold shutdown modes at the Millstone Unit 2 facility in early 1980, it was discovered that an incorrect assumption had been made. The analy91s of this event while in Mode 5 (cold shutdown) had assumed a full reactor coolant system and a 1% shut /own margin. The result of this analysis showed that it would take 20 minutes of uncontrolled boron dilution before the reactor returned to criticality. This satisfied the 15 minute maximum time interval assumed for the operators to recognize the situation and take appropriate action. However, the analysis had not considered the fact that operation is permitted with the 4
reactor coolant system drained to the centerline of the hot let.
Including this reduced volume of reactor coolant to be diluted in the l
analysis results in a time to reach criticality of less than 14 minutes.
The Millstone facility corrected this problem by revising their Technical Specifications to require a minimum 2% shutdown margin while in Mode 5.
By making this change, a time to criticality of greater than 15 minutes is reestablished.
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We request that you recalculate the boron dilution event, using the 4
4 drained down RCS volume and the 15-minute criteria required by SRP 3
15.4.6 for hot and cold shutdown medes. If the result of the recalculation shows that the time interval would be greater than 15 minutes, we request that yoit provide procedural changes and propose a Technical Specification change to require a greater shutdown margin or an acceptable alternate proposal within 90 days of receipt of this letter.
Sincerely.
0107210446 810/10 PDR ADOCK 05000313 P
PDR John F. Stolz, Chief operating Mactors Branen 74
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Arkansts Power & Light Company ccw/ enclosure (s):
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Mr. David C. Trimble
. Manager, Licensing Arkansas Power & Light Company P. O. Box 551 Director, Bureau of Environmental Little Rock, Arkansas 72203 Health Services 4815 West Markham Street Mr. James P. O'Hanlon Little Rock,,* dansas 72201 General Manager
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Arkansas Nuclear One P. O. Box 608 Russellville, Arkansas 72801 W..y Mr. William Johnson U.S. Nuclear Regulatory Comission P. O. Box 2090 Russellville, Arkansas 72801 Mr. Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 420, 7735 Old Georgetown Road Bethesda, Maryland 20014 Mr. Nicholas S. Feynolds Debevoise & Liberman 120017th. Street, tal Washington, DC 20036 Arkansas Tech University Russellville, Arkansas 72801 1
Honorable Ermil Grant Acting County Judge of Pope County Pope County Courthouse Russellville, Arkansas 72801 9
U. S. Environmental Protection Agency Region VI Office ATTN: EIS COORDINATOR 1201 Elm Street
.First International Building
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