ML20054J010
| ML20054J010 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 06/14/1982 |
| From: | Tourigny E Office of Nuclear Reactor Regulation |
| To: | William Jones OMAHA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 8206250336 | |
| Download: ML20054J010 (3) | |
Text
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Distribution:
Docket File NRC PDR Docket No. 50-285 Local PDR ORB #3 Rdg DEisenhut JHeltemes PKreutzer Mr. W. C. Jones ETourigny Division Manager MConner Production Operations OELD Omaha Public Power District 01&E (1) 1623 Harney Street NSIC Omaha, Nebraska 68102 ACRS (10)
Dear Mr. Jones:
It has come to our attention that Page 4 of Enclosure 2 was inadvertently omitted from our March 31, 1982 letter regarding the independence of the Reactor Proj4ction System. Since this page could affect your future actions on this subject, it is enclosed with this letter.
Please accept our apology for any inconvenience this overs:i~ ht has caused -
g you.
Sincerely, Edward Tou gny froject Manager Operating Reactde's Branch #3 Division of Licensing
Enclosure:
As stated cc w/ encl:
See next page 8206250336 820614 PDR ADOCK 05000285 PDR
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Omaha Public Power District cc:
Marilyn T. Shaw, Esq.
LeBoeuf, Lamb, Leiby & MacRae
,1333 New Hampshire Avenue, N.W.
Washington, D. C.
20036 Mr. Jack Jensen Chairman, Washington County Board of Supervisors Blair, Nebraska 68023 U.S. Environmental Protection Agency Region VII ATTN:
Regional Radiation Representative 324 East lith Street Kansas City, Missouri 64106 Mr. Frank Gibson W. Dale Clark Library 215 South 15th Street Omaha, Nebraska 68102 Alan H. Kirshen, Esq.
Fellman, Ramsey & Kirshen 1166 Woodmen Tower Omaha, Nebraska 68102 Mr. Larry Yandel.1 U.S.N.R.C. Resident Inspector P. O. Box 309 Fort Calhoun, Nebraska __68023 Mr. Charles B. Brinkman Manager - Washington Nuclear Operations C-E. Power Systems Combustion Engineering, Inc.
4853 Cordell Avenue, Suite A-1 Bethesda, Maryland 20014
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Regional Administrator Nuclear Regulatory Commission, Region IV Office of Executive Director for Ophrations 511 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011 e
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e) Acceptance criteria for perturbations which wculd be allowed within the redundant vital bus without interfering with any protection syste r.:tions, f) Justification that the faults and surges used during the testing exceed the maximum worst-case failures which could occur within the protection systems circuits.
'5.
Looic Matrix Circuitry Failure Due to a Vital Bus Sinale Failure Each plant must be reviewed to assure that, with a channel in bypass, a single failure of a vital bus will not prevent the protection system from performing its protective function.
As stated in item 4 above, the CE reactor protection system forms six logic matricies (AB, AC, AD, BC, BD and CD) from all possible coincidences of two combinations of the four protection channel bistables and associated contacts.
Due to the vital bus arrange-ment a single failure of a vital bus coincident with the bypass.of a channel could prevent the required protective function of the RPS.
Looking at figure-1, assume that a channel A trip parameter is l
bypassed. ' This results in negating the AB, AC and AD logic matricies protective functions.
This now leav.es the BC, BD, and CD logic matricies for protection.
However, as shown in figure 1, these remaining matricies are being supplied by a common vital bus.
It can now be postulated that a single failure (fault, surge, etc.) within the common vital bus system might propogate through the logic matrix power supplies into the matrix circuitry. This could thereby cause a failure (welding of contacts) of the remaining logic
~
matricies such that the required protective function cannot be per-