ML20113A321
| ML20113A321 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 11/09/1984 |
| From: | Tucker H DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-85-122-000 PT21-85-122, PT21-85-122-000, SD-414-84-21, NUDOCS 8501210057 | |
| Download: ML20113A321 (3) | |
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DUKE POWER GOMPANY P.O. BOX 33180 CHAMLOTTE, N.C. 28242
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84 MOV $ ?,[3e p ), 1984 3o Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Re: Catawba Nuclear Station, Units 1 and 2 Docket No. 50-414
Dear Mr. O'Reilly:
Pursuant to 10 CFR 50.55e, please find attached Significant Deficiency Report SD 414/84-21.
Very truly yours, fh Hal B. Tucker RWO: sib Attachment cc: Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555 NRC Resident Inspector Catawba Nuclear Station Palmetto Alliance 21351s Devine Street Columbia, South Carolina 29205 INP0 Records Center Suite 1500 1100 circle 75 Parkway Atlanta, Georgia 30339 Robert Guild, Esq.
P. O. Box 12097 Charleston, South Carolina 29412 I220057 g OFFICTAL COPF B
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Duke Power Company Catawba Nuclear Station
' REPORT NUMBER: SD 414/84-hL.
Al REPORT DATE: November 9,'1984 ~
-FACILITY: CATAWBA NUCLEAR STATION, UNIT 2.
IDENTIFICATION OF DEFICIENCY: The Component Cooling Water System could potentially become overpressurized should a tubing failure occur in the reactor coolant pump thermal barrier heat exchanger.
'- INITIAL REPC' T:' On 10/11/84, Al Ignatonus (NRC) was informed by L. M.
Coggins. T. L. Utterback and R. C. Gambert (all Duke Power Co., 422 South Church Street, Charlotte, N.C.
28242).via telephone. Due to a clerical error the initial report was not'made-within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the problem being evaluated as reportable. The initial report was made the next day and we made Mr. Ignatonus aware that we had inadvertently delayed the initial report.
ACTIVITY: This deficiency pertains to criteria used by. Duke Power Co.
in the design of the Component Cooling System. This criteria was-initially 'provided by the NSSS vendor (Westinghouse)' and subsequently revised by them. Westinghouse has indicated that they have reported this deficiency pursuant to 10 CFR 21 for projects where they have provided the design of the Component Cooling System.
DESCRIPTION OF DEFICIENCY: A tube failure in a heat exchanger cooled by the Component Cooling Water System could overpressurize the system.
The limiting case is an assumed rupture of a tube in a reactor coolant pump thermal' barrier heat exchanger. This would result _in a maximum leak rate of 260 gpm (calculated) from the Reactor Coolant-System into the Component Cooling Water System. This leakage would appear as additional fluid in the' surge ranks. The surge tanks are normally
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' vented to atmosphere via a 4" vent line containing an air operated valve which receives a signal to close on high radiation in the component cooling system. Once'this valve closes (as would-be expected due to the activity of'the reactor coolant inflow) the only overpressure protection for the tanks ~would be a~2" overflow line.' The resultant
. pressure losses in this line would overpressurize the surge tank'and portions of the system piping.
ANALYSIS OF SAFETY IMPLICATIONS: A single tube ruptu e in a reactor-coolant pump thermal barrier heat exchanger could generate. fluid pressures in excess of piping and component design pressures. Since the two Component Cooling System trains are connected during normal operation, both could be affected by such a failura. Consequent damage.
to both trains of component cooling could result'in loss of cooling to essential equipment (including reactor coolant pumps, charging', pumps..
etc.).
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- CORRECTIVE ACTION: ' Overpressure protection for-the surge tanks'will be provided_by assuring that the vent valve on each surge tank remains open. A calculation has been performed which shows that the open 4" tank vent provides adequate overpressure protection.
Closure of this valve is not required to prevent an uncontrollable release to the environment of gaseous activity normally' required to be held for decay. Surge tank overflow is directed to the component cooling drain sumps, where it can be pumped to the mixing and settling tank in the Liquid Radwaste System for disposal.
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