ML20105A730
| ML20105A730 | |
| Person / Time | |
|---|---|
| Site: | U.S. Geological Survey |
| Issue date: | 09/09/1992 |
| From: | Danni Smith INTERIOR, DEPT. OF, GEOLOGICAL SURVEY |
| To: | Callan L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| NUDOCS 9209170203 | |
| Download: ML20105A730 (2) | |
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~i United States Department of the Interior REn-
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m GEOLOGICAL SURVEY BOX 0504 M.S._973 "Em" "a
DENVER FEDERAL CENTER DENVER, COLORADO S0225
- n nm eme to Septer.ber 9, 1992 8
U.S. Nuclear Ragulatory Commission ATTN:-Mr. L.J. Callan 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011 4
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We received notification of an apparent generic problem with the General Atomics (GA) digital control consoles tim oppears to apply to_our facility.
This letter is to noti.' vou that this problem involves one of the Technical Specified ion requirements of our license and could potentially cause the violation of a re'. aired interlock for pulsing operations.
Personnel at the AFRRI reactor facility noticad that if a standard control rod was being raised at the, 4.nstant the console was switched into the pulse mode, that coni tol rod would continue to move up even if the Reactor Operator released the UP button.
The rod would stop moving if the DOWN button was depressed, or if the reactor was SCRAMMED.
Once the rod motion stopped,'the pulse interlock properly prevented any further motion.- If'no. rod motion was occurring when the console was switched into the pulse mode, the interlock properly functioned
-to prevent any_ motion of the st6ndard control rods.
This characteristic was checked at the GA facility in San Diego and they found the same response with their console, when switching to either the pulse or square wave modes.
GA personnel then~ notified.us of the problem late on Friday, l September 4.
We examined our console response when switching to the' square wave mode-(with the reactor shutdown) and found that rod motion continues if the rod is moving when'the-modi is u
switched.
The only pulsing operations we have perfortad were during the initial console checkout in April of 1991.
We have not been able to pulse.in the last few months due to an unrelated ~ problem with.the control console.
Our Technical Specification Table II requires that the withd val.of any control rod except the pulse rod must be preve.~ed in the pulse mode. _ It appears that_this requirement Ewould-not be met if an operator was withdrawing a control rod during the mode switching.
Our procedure for pulse mode oper.ations' requires that the operator adjust the standard conb sl.roa positions-to their desired levels prior to switching 9209170203-920909
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's to - the ' PULSE mode, thus preventing loss of the required interlock.
Despite this, wr will not perform any critical pulsing operations until GA has resolved tha problem with the pulse mode interlock.
We will need to perform the pulse sequence in a-shutdown condition for troubleshooting and resolution verificatien.
It is our understanding that this problem exists on all new GA digital consoles at puising (uciliti's, so we have hope for a quick resolution.
We will keep you nformed of any progress.
- If you have any questions regarding this matter, please contact the Reactor Supervisor, Tim DeBey, at (303) 236-4726.
Sincerely,
[470b t-David B.
Smita Reactor Administrator Copy to:
Al Adams, NRR USNRC Washington, D.C.
20555
-Tim DeBey, MS 974 Y
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