ML19291C014
| ML19291C014 | |
| Person / Time | |
|---|---|
| Issue date: | 12/07/1979 |
| From: | Colmar R Office of Nuclear Reactor Regulation |
| To: | Burger C NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| REF-GTECI-A-01, REF-GTECI-PI, TASK-A-01, TASK-A-1, TASK-OR NUDOCS 8001030362 | |
| Download: ML19291C014 (2) | |
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UNITED STATES 3 #,( (,g NUCLEAR REGULATORY COMMISSION "j
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% *****p DEC 071979 NOTE T0: Charles W. Burger Division of Reactor Safety Research FROM:
Robert J. Colmar Plant Systems Branch Division of Operating Reactors
SUBJECT:
TAP A-1, COMMENTS ON EG&G WATER HAMMER EFFORT AND BNL REPORTS As you requested rece,tly, I have reviewed the EG&G work scope on the water-hammer-scenarios effort and I've completed a preliminary review of some BNL waterhammer reports.
On the EG&G work scope I have essentially minor comments, as indicated in the enclosure.
LER's required in item 5 as NRC input to the task.In connection with this ef In addition, I am prompted to make the following observation related to this task, for your information, as a result of a recent "waterhammer" occurrence at Oconee, Unit 3.
One of the potential difficulties in establishing the perimeter of the scen rios for water hamer events is exemplified by the recent occurrence at Oconee.
I refer to this occurrence only as a way to illustrate tha virtual " infinity" of possibilities that are possible in a system as complex as a nuclear plant There is nothing particularly significant about this occurrence per se,.other than as a convenient illustration.
01 November 10, the main condensate pumps tripped out because of a spurious occurrence during a routine maintenance check. Within minutes tre turbine and reactor also tripped out.
Following this, as described in the I&E Information Notice No. 79-29, the inverter power supply failed to transfer automatically from the DC source to the regulated AC source.
This caused a power failure to the integrated control sys tem and, therefore, all the valves controlled by this system lost power and proceeded to their " fail" positions.
Subsequently, the inverter was switched manually by the operator and power was restored to the valves, whereupon the valves resumed their normal positions based on the system instrumentation signals. Sometime during the valse positioning changes a water haniner shock was known to occur; one
~1790 238 9 00/0303 @
e Charles W. Burger DEC 0 7 E 3 or more main feedwater recirculation line valve stems were found broken off.
The event was rightfully classified as an instrumentation malfunction, but the water hammer damage was considered to be of such a minor nature that it was not reported in the official notification or bulletin. This is not a criticism of the reporting methods,but for those of us that are searching for scenarios in reactor operating experience it does illustrate how important sequence details can be lost to us.
In the case of Oconee Unit 3 the consequences were minor but the insight into the interaction of electrical and hydraulic systems, for example, might be valuable in judging other parts of the plant and other subsystems.
However, one can only guess at the ir. estimable loss of detail in the multitude of the other reportable events.
I have no answer for this problem but I believe that it is worthwhile to be aware of it.
Perhaps this awareness could justifiably lead to the requirenent that every safety-related system be designed explicitly for water hammer loads, regardless of an establis ted scenario for that system.
In another connection,I have made a preliminary review of some BNL reports on water hammer; one, a letter from Pradip Saha to Victor Ber.arew, dated November 21, 1979; and the other was BNL NUREG-26789, by 0.C. Jones, et al, dated June 1979.
My impression, based on this preliminary review, is that I have reservations about the technical value and the clarity of these reports.
It is not clear to me how the BNL work could be useful to our effort.
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Robert J. Colmar Plant Systems Branch Division of Operating Reactors cc w/o enclosure:
E. Adensam M. Aycock F. Chernev 6 Hanau'e D b.
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C.P. Tan J. Zwolinski
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