ML20245B615
| ML20245B615 | |
| Person / Time | |
|---|---|
| Issue date: | 03/30/1987 |
| From: | Cintula T NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Rubin S NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| Shared Package | |
| ML20245B616 | List: |
| References | |
| AEOD-E706, NUDOCS 8904260188 | |
| Download: ML20245B615 (2) | |
Text
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WASHINGTON, D. C. 20666 March 30, 1987 1
AE00/E706 MEMORANDUM FOR:
Stuart D. Rubin, Chief Reactor Operations Analysis Branch i
Office for Analysis and Evaluation of Operational Data THRU:
Patrick W. Baranowsky, Chief Reactor Systems Section 1 Reactor Operations Analysis Branch Office for Analysis and Evaluation of Operational Data FROM:
Theodore C. Cintula, Reactor Systems Engineer Reactor Systems Section 1 Reactor Operations Analysis Branch Office for Analysis and Evaluation of Operational Data
SUBJECT:
MECHANICAL BLOCKING OF VALVES
' Enclosed for your information is a copy of the subject AE0D Engineering Evaluation Report. The study investigated 19 events of mechanical blocking of
. automatic valves in a.five-year period from October 1981 to February 1986.
fline of the events involved the application of mechanical blocking devices to safety / relief valves..In each event, the gagging of the safety / relief valve led to a desirable safety outcome.
The remaining ten events in this study involved the misapplication of a mechanical blocking device to one motor-operated and nine air-operated valves. The study found:
1.
Six of the valves were inadvertently blocked from automatic motion and where incapable of responding to a remote command.
2.
There was one instance of a mechanical blocking device failing and it was incapable of preventing undesired valve motion.
3.
Two automatic valves should have been mechanically blocked in the " safe" position; they were not and each valve subsequently cycled to a position that led to degradation of safety-related equipment at the plant.
The study found that the misapplication of mechanical blocking devices to automatic valves was caused by hv. man error deficiencies, i.e., personnel errors or inadeouate procedures. The events were not repetitive at any individual plant so it would appear that the corrective actions taken at these specific plants were effective.
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8904260188 870330 PDR ORG NEXD
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l l-Stuart D. Rubin Although this study found that the misapplication of mechanical blocking devices were infrequent, unrepetitive occurrences, a high pr: portion of the events could have and actually did result in significant compromises in safety. Accordingly, it is suggested that IE consider issuing an information notice to describe several of these events and their underlying cause and i
actions that could be taken to minimize the possibility of these types of problems. Also, because the misapplication of mechanical blocks was identified as a human performance problem, it is suggested that this report be forwarded to NRR, Division of Human Factors Technology, Maintenance Training Branch, to determine if the maintenance and surveillance plan adequately addresses the human performance problems identified in this report.
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1 Theodore C. Cintula, Reactor Systems Engineer Reactor Systems Section 1 Reactor Operations Analysis Branch Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated cc w/ enclosure:
T. Gwynn, OCM C. Heltemes, Jr., AE00 F. Hebdon, AE0D J. Crooks, PTB S. Massaro, PTB M. Beaumont, W C. Brinkman, TE R. Borsum, BSW L. Gifford, GE L. Licitra H. Rood, NRR R. Huey, RV R. Zimmerman, RV
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