ML19263E977
| ML19263E977 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/06/1979 |
| From: | Flynn W AFFILIATION NOT ASSIGNED |
| To: | NRC COMMISSION (OCM) |
| Shared Package | |
| ML19263E978 | List: |
| References | |
| NUDOCS 7910170327 | |
| Download: ML19263E977 (2) | |
Text
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LAW f 9CEs or OLTMAN AND FLYN N REarsTERED PATENT ATTORNEYS 415 SUNRISE PROFESSION A6 SUILDING 915 MIOcLE river C Riv E FORT LAUCERDALE. FLoRicA 33304 April 6, 1979 rv.'Au=EmoAst 30.<=.=
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.oL, NAN WILLIAM J. FLYNN Ma Ami 305 / 947..s e e 14 5o N.E.157tM TEmm.
... a Nuclear Regulatory Commission Washington, D.C.
G atlemen:
The accident in Pennsylvania indicates the need for more sophisticated controls in the reactor cooling systems.
My understanding from the newspaper accounts is that the emergency cooling system is merely a standby system which is called up to provide cooling water only in the event of a failure of the primary cooling system.
Some worker turned off a manual valve and this prevented the emergency cooling system from functioning at all.
Modern control systems for punch presses and other machines of that type are much more sophisticated.
They use paired, duplicate control elements (limit switches, relays, valves) to provide re-dundancy so that both control elements of a given pair must fail simultaneously for a dangerous malfunction to occur.
If just one control element of a particular pair fails, the mach?.ne is stopped and cannot endanger the operator.
The various control elements are interconnected electrically so that the performance of each one is monitored throughout each cyc1c of operation.
Such press controls do not rely on a mere standby system which just sits there passively, doing nothing, untti the primary control system fails.
Instead, they are based on the concept of a: t-ive redundancy - every control element (which is duplicated by another in the system) is put through its paces during each cycle of operation.
That is, each limit switch must open and close, each relay must be energized and de-energized, and each valve must open and close, at appropriate. times in each operating cycle.
The basic philosophy is that the best assurance t' a control element will perform properly the next time is the fact c'
it did perform the last time.
2219 014 7910170 h 7
L Aw Crricts or OLTMAN AN o FLYN N April 6, 1979 Nuclear Regulatory Commission OSHA has mancated " interrupted stroke protection" for press controls which reflect this philosophy.
I suggest that you consider whether some of these ideas might be transferred to the technology of nuclear reactor cooling.
If you are interested, I can put you in touch with an inventor / client who is an expert in the press control field and who, I am sure, would be agreeable to working with you on this very serious problem.
Very truly yours, OLTMAN AND FLYNN William J. F ynn WJF:lh 2219 015 m
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