ML20135F717
| ML20135F717 | |
| Person / Time | |
|---|---|
| Issue date: | 09/09/1985 |
| From: | Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Rossin A NUCLEAR SAFETY ANALYSIS CENTER |
| Shared Package | |
| ML20135F678 | List: |
| References | |
| NUDOCS 8509170367 | |
| Download: ML20135F717 (2) | |
Text
r e
- SEP ou n
! Dr. A. David Rossin Director Nuclear Safety Analysis Center 3412 Hillview Avenue P.O. Box 10412 Palo Alto, California 94303
Dear Dr. Rossin:
Subject:
Case Study Report -- Overpressurization of Emergency Core Cooling Systems in Boiling Water Reactors t
! Following resolution of peer review comments from NSAC, INP0 end various
! NRC offices, the Office for Analysis and Evaluation of Operational Data l has finalized its case study of operational events involving an actual or potential overpressurization of an emergency core cooling system in boiling water reactors. We have enclosed a copy of our final report for your informa-tion and use as you may deem appropriate.
A total of eight events, each entailing the failure of a testable isolation
! check valve on the injection line of an emergency core cooling system, were I identified and evaluated in the study. Five of the eight events involved an
! additionel failure of the second and final isolation barrier -- the inadver-
! tent opening of a normally closed motor-operated injection valve. Four of these five events occurred during power operation, thus leading to an actual overpressurization of an emergency core cooling system. Collectively, these operational events indicate a trend with serious safety implications, that the l
likelihood of an interfacing loss-of-coolant accident between the reactor coolant system and an emergency core cooling system is higher by two to several orders of magnitude than had been previously assessed.
The enclosed case study report contains several reconnendations aimed at addressing the root causes of the reported multiple failures. These reconnenda-l tions are currently being reviewed by the Nuclear Regulatory Commission staff.
l l A copy of the final case study report and this letter are being placed in the
! Public Document Room at 1717 H Street, ll.W., Washington, D.C. 20555, i
l 0509170367 050909 PDR MISC 8509170354 PDR
I l 1, e-i . Dr. A. David Rossin l l
If you have any questions regarding this report, please feel free to contact Peter Lam of my staff. Dr. Lam can be reached at (301) 492-4438.
Sincerely, Onginal signed by C. J. Heltemes, Jr.
C. J. ' Heltemes, Jr. , Director Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated Distribution:
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