ML20053C367
| ML20053C367 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 05/21/1982 |
| From: | Adensam E Office of Nuclear Reactor Regulation |
| To: | Parker W DUKE POWER CO. |
| References | |
| NUDOCS 8206020009 | |
| Download: ML20053C367 (5) | |
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Docket Nos.: 50-413/414 GCC !v59, Q
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[4 %ID7 Mr. William O. Parker, Jr.
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Vice President - Steam Production P.O. Box 33189 Charlotte, North Carolina 28242 c'
Dear Mr. Parker:
Subject:
Request for Additional Information - Catawba Nuclear Station l
In the performance of the Catawba Station licensing review, the NRC staff has l
Identified additional concerns in the Instrumentation and Control Systems area as stated in the Enclosure. We request that you provide the information needed no later than June 30, 1982.
If you require any tiarification of this matter, please contact the project manager, Kahtan Jabbour, at (301) 492-7821.
The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under P.L.96-511.
Sincerely, Elinor G. Adensan, Chief Licensing Branch Ho. 4 Division of Licensing
Enclosure:
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" CATAWBA Mr. William 0. Parkes-Vice President - Steam Production Duke Power Cogany P.O. Box 33189 Charlotte, North Carolina 28242 cc: William L. Porter, Esq.
North Carolina Elec.cric Membership Duke Power Company Corp.
P.O. Box 33189 3333 North Boulevard Charlotte, North Carolina 28242 P.O. Box 27306 Raleigh, North Carolina 27611 J. Michael McGarry, III, Esq.
Debevoise & Literman Saluda River Electric Cooperative, 1200 Seventeenth Street, N.W.
Inc.
Washington, D. C.
20036 207 Shemood Drive Laurens, South Carolina 29360 North Carolina MPA-1 P.O. Box 95162 Mr. Peter K. VanDoorn Raleigh, North Carolina 27625 Floute 2, Box 179N York, South Carolina 29745 Mr. F. J. Twogood Power Systems Division James P. O'Reilly, Regional Administrator Westinghouse Electric Corp.
U.S. Nuclear Regulatory Commission, P.O. Box 355 Region 11 Pittsburgh, Pennsylvania 15230 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 Mr. J. C. Plunkett, J r.
NUS Corporation Robert Guild, Esq.
2536 Countryside Boulevard 314 Pall Mall Cleamater, Florida 33515 Columbia, South Caroline 29201 Mr. Jesse L. Riley, President Palmetto Alliance Carolina Environmental Study Group 2135 1/2 Devine Street 854 Henley Place Columbia, South Carolina 29205 Charlotte, North Carolina 28208 Richard P. Wilson, Esq.
Assistant Attorney General S.C. Attorney General's Office P.O. Box 11549 Columbia, South Carolina 29211 Mr. Henry Presler, Chairman Charlotte - Mecklenburg Environmental L
Coalition
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943 Henly Place Charlotte, North Carolina 28207
ENCLOSURE INSTRUMENTATION AND CONTROL' CONCERNS FOR CATAMBA During our review of the UHI system,'we have been concerned with the adequacy of instrumentation and control features provided. These concerns are centered on the following characteristics of this system:
- 1) Termination of injection by the UHI system is effected automatically by the use of local level switches. This makes surveillance of the system difficult if not impractical daring power operation and therefore greatly reduces the confidence in its ability to perform its required safety function.
- 2) The valves used to terminate upper injection utilize accumulators to effect automatic fast closure. Manual closure is only provided by the use of the hydraulic oil pump, closing one valve at a time. The hydraulic oil pump is not safety grade and valve closure by this means is a slow process.
- 3) Level indication is only provided for the accumulator surge tank and not for the accumulator itself.
The Easic concern with this design is that the total emphasin appears to con-sider only the large break LOCA and not other potential r,ents.
For small and intermediate break LOCA's, steam generator tube ruptures and overcooling events it would appear that with better control and indication features in the design of the UHI system a significant improvement could be provided for the operator to cope with these events.
' The argument for not providing ' safety grade manual closure of the termination valves, is that the transient is so fast that operator action would not be possible. While this may be true for a large break LOCA, perhaps operator action to prevent operation of the UHI system might be important for severe overcooling transients or for steam generator tube rupture accidents where it might be a goal to prevent the UHI system from maintaining reactor coolant system pressure.
Providing level indication would appear to be useful for all events to either confirm discharge of the UHI accumulator or not, whichever may be desired.
With present designs a relative indication of level can be inferred from pressure indication. This in itself would be one means to provide diversity as a backup means to terminate injection.
The level switches used to automatically terminate UHI injection are differ-ential pressure indicating switches which sense the height of water in the accumulator.
Since the sensing connections are on the water accumulator which is water solid, level indication is normally pegged full scale. This further reduces the ability to perform surveillance to confirm that indication is normal.
It would have been preferable if level transmitters had been used with an indicating range that extends to the normal water level in the surge tank. This would permit surveillance to confirm that the readings of all channels are normal and thus provide greater confidence in the systems oper-abili ty. McGuire Unit 1 LER 82-13 confirms to an extent the problems noted with present systems.
The following questions summarize concerns that ICSB has on the adequacy of the design of UHI systems.
- 1) What is the safety significance of the automatic termination of UHI injection for a large break LOCA? Should diverse means be provided to terminate injection and/or should the design te modified to improve surveillance capabilities?
- 2) Should features be provided to insure a safety grade neans to manually close valves to block UHI system operation for events other than a large break LOCA? Further, should plant procedures be revised to include specific instruction for their use, such as AT0G?
- 3) Should a direct indication of water level be provided for UHI accumulators as a means to confinn the safety actions of the system or for use in events other than large treak LOCA?
We would like to discuss your response to the above questions and any other comments relative to this issue which you may have based on the concerns and our interpreta-tion of this subject noted above.
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