ML20023A743

Interim Deficiency Rept Re Potential Reportable Deficiency 86 on Disparity in UHS Tornado Case Test Results.Initially Reported on 820830.Equipment Not Significantly Impacted at 104 F.Deficiency Not Reportable Per 10CFR50.55(e)

ML20023A743
Person / Time
Site:	Waterford
Issue date:	10/06/1982
From:	Maurin L LOUISIANA POWER & LIGHT CO.
To:	Madsen G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
10CFR-050.55E, 10CFR-50.55E, W3I82-0049, W3I82-49, NUDOCS 8210190542
Download: ML20023A743 (3)

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m LOUISIANA 142 OELARONDE STREH P O W E R & L l G H T! P O BOX 6000 + NEW DALEANS. LOUISIANA * (504) 366-234570174 so m UTiuTis system Vice President Nuclear Operations W3I82-0049 Q-3-A35.07 l 3-A1.01.04 i

Mr. G. L. Madsen O Reactor Projects Branch, Region IV U. S. Nuclear Regulatory Commission I f 611 Ryan Plaza Drive, Suite 1000 (

Arlington, Texas 76012 l i

SUBJECT:

Potential Reportable Deficiency #86, " Disparity in Ultimate Heat Sink Tornado Case Test Results"

REFERENCE:

W3I82-0020, Documentation of felephone Communications, W. A. Cross to W. A. Crossman/L. Martin dated 8/30/82 On Monday August 30, 1982 a disparity in Ultimate Heat Sink Preoperational Test results for the tornado loading case was reported as Potential Reportable Deficiency #86. This letter is to inform you that after further evaluation, this specific problem is not considered to be reportable pursuant to the requirements of 10CFR50.55(e).

BACKGROUND The Waterford 3 Ultimate Heat Sink (UHS) consists of dry and wet cooling towers and water stored in the wet cooling tower (WCT) basin. One of the design bases of the UHS is to dissipate heat removed by the Component Cooling Water System and the Auxiliary Component Cooling Water System from the reactor and its auxiliaries to permit safe shutdown of the unit coincident with a loss of offsite power, multiple tornado missiles and a single active failure.

On each train three of the five dry cooling tower (DCT) cells are missile protected. The remaining DCT cells and the WCT cells are unprotected from certain missiles. Under the assumptions of the tornado missile scenario described above, the plant must rely on one train of the protected DCT's (3 ceits) and one train of the WCT's acting in a natural circulation mode. It has been determined that this configuration will, in fact, provide sufficient heat removal capability to allow safe shutdown of the plant under these design basis conditions.

8210190542 021006 PDR ADOCK 05000382 .-

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,s Mr. G. L. Madsen October 6,198?

Page 2 EVENT Each train of the Essential Services Chilled Water System (ESCWS) consists of: one water chiller, one chilled water pump, one expansion tank, instrumentation and controls, and piping and valves (FSAR 9.2.9). The ESCWS furnishes chilled water to air handling systems which cool spaces containing equipment required for safety-related operations. Heat is rejected from the ESCWS t7 the Component Cooling Water System which rejects its heat to the Ultimate Heat Sink, specifically the WCT basin. Ce.lculations have shown that in order to ensure that cafety-related plant areas cooled via the ESCWS are maintained at or belcw 104'F the CCW return temperature from the WCT basin must be less than 105'F.

The cooling towers were recently tested for performance under the design basis tornado missile conditions. During this test it was observed that the WCT basin water temperature rose to 118'F and stabilized there. It has been determined that this would cause temperatures in certain safety-related areas to exceed their design ambient temperatures.

The areas involved, their design ambient temperature (DAT), and their post tornado peak cemperatures are as follows:

Post Tornado Area DAT (F*) Peak Temperature (F')

CCW Heat 104 109 Exchanger Room CCW Pump Room 104 115 Emergency FW 104 113 ,

Pump Room (Motor Driven)

Shutdown Cooling 104 111 Heat Exchanger Room EVALUATION No areas containing sensitive safety-related electrical equipment, such as, the Switchgear Room, Control Room, cr Relay Room exceeded their design ambient temperatures under this tornado-missile scenario. The concern focused on the environmental qualification of the equipment in the four (4) rooms as described above. The safety-relatdd equipment in these areas, was specified to operate ~ in an environment with temperatures of 104'F.

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4 Mr. G. L. Madsen.

October 6, 1982 Page 3 i'

Worthy of mention is the fact that there are conservatisms in the Environmental

-Qualifications analysis. It should also be noted that for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the tornado event the plant is maintained in hot standby conditions via the' Emergency Feedwater System. Only after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when plant cocidown commences does the environment in these rooms exceed the 104*F DAT and then only for a brief period of time compared to a 40 year operating lifetime.

These temperature excursions were forwarded to the Ebasco Environmental Qualification Task Group for analysis. Their analysis. consisted of evaluating the environmental effects of operating these rooms at their average normal operating temperatures plus the brief minor temperature excursion described above versus; operating.at the design ambient temperature of 104'F for forty

. years. The conclusion is that the latter is more conservative for the equipment located in these areas and that the qualified life of equipment present in these areas would not be significently impacted.

CONCLUSION The concern this situation presented was not for the ability to safely shut down. The heat dissipation capacity of the three operable Dry Cooling Tower cells and the Wet Cooling Towers in natural circulation were sufficient for that purpose. Based on the above evaluation the event is not considered significant nor has any impact on the Waterford 3 Environmental Qualification Program.

Thus this event is not reportable under 10CFR50.55(e).

Ver truly yours, L. V. Maurin LVM/WAC:keh i