ML20062H190
| ML20062H190 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 11/28/1990 |
| From: | Haseltine J YANKEE ATOMIC ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20062H197 | List: |
| References | |
| BYR-90-155, NUDOCS 9012040169 | |
| Download: ML20062H190 (3) | |
Text
..
YkNKEE ATOMlC ELECTRIC COMPANY
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580 Main Street, Bolton, Massachusetts 017401398
. YANKEE v.
November 28, 1990 BYR 90-155 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Attention:
Mr. Patrick Sears Senior Project Manager Division of Reactor Projects - I/II Office of Nuclear Reactor Regulatjen N,
(Docket No. 50-29)
References:
(a) Licensa No. D (b) Letter, NRC to 'linkee Atomic Electrifdompany, dated August 31, 1990 (c) Letter, Yankee Atomic Electric Company to NRC, dated September 28, 1990 y
Subject:
Reactor Pressure Vessel Fluence Assessment
Dear Sir:
As noted in.the NRC Safety Assessment of the Yankee reactor pressure-vessel (Reference (b)), Yankee committed to preparing-and submitting an updated fluence analysis by October 1, 1990.
In a telecon with
'Dr. Thomas Murley, NRC, on September 25, 1990 Mr. John DeVincentis of Yankee Atomic Electric Company (Yankee) reported the preliminary results of the updated fluence analysis and informed Dr. Murley that Yankee wculd not be able.
r to meet the October 1, 1990 submittal date for the final updated fluence analysis because'further work had to be performed in order to verify the preliminary results and assess their effects.
In a-subsequent telecon between the NRC and Yankee on September 26, 1990, it was agreed that the safety assessment performed by Yankee on the preliminary fluence values would be submitted on September ~28, 1990 (Reference (c)) and that the final updated fluence analysis would be submitted within 60 days of the telecon.
Per>the 60-day commitment, please find enclosed'the results of-the final updated fluence (Attachment A) and PTS analyses (Attachmant'B) for the Yankee reactor pressure vessel.
The fluence = distribution and associated mean reference temperatures for the beltline materials have been recalculated and are shown in Tables 1 and 2 of Attachment B..
The methodology for determining the reference temperatures is the.same as that given in Reference (c).
9012040169 901128 POR ADOCK 05000029 n$;
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United States Nuclear Regulatory Commission November 28, 1990 Mr. Patrick Sears Page 2 BYR 90-155 The PTS fracture mechanics analysis has also been re-evaluated for the limiting thermal hydraulic parameters from the small break LOCA. The small break LOCA is dominant because it has the highest combination of conditional failure probability and event frequency.
The reference temperatures for each material were input into the VISA-II Code as before. The distribution of input parameters, flaw density using the Marshall distribution, flaw length, assumption of one flaw per beltline material, and number of simulations were identical to previous submittals to the NRC. As provided in Table 3 of Attachment B, the results indicate a conditional failure probability of 6.51 x 10-3 The total vessel failure probability based on the final fluence analys!s is 3.25 x 10-6/ reactor-year which is below the NRC criteria of 5 x 10-6/ reactor-year.
Thus, Yankee is still within the baunds of the NRC Safety Assessment and continued operation of the Yankee plant is justified.
If you should have questions concerning the enclosed assessment, please notify me.
Sincerely, h
John D. Haseltine Director Yankee Project JDH/gjt/WPP77/216 Attachments cc:
B. Elliot (NRC, NRR)
R. Wessman (NRC, NRR)
W. Russell (NRC, NRR)
Attachment A Plant Specific Fast Neutron Exposure Evaluations for the First 20 Operating Cycles of the Yankee Rowe Reactor i
I h
.