ML17208A743

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Responds to IE Bulletin 80-05.Existing Measures for Vacuum Protection Are Adequate & No Further Mods Are Required
ML17208A743
Person / Time
Site: Saint Lucie NextEra Energy icon.png
Issue date: 06/11/1980
From: Robert E. Uhrig
FLORIDA POWER & LIGHT CO.
To: James O'Reilly
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
IEB-80-05, L-80-178, NUDOCS 8006250307
Download: ML17208A743 (3)


Text

P.o. BOX 529100, MIAMI, FL 33162 I

y)l Ili,p USNRC REC-'I'I't "

.4 ILANTA I-.I, nI'eIr FLORIDA POWER 8 LIGHT COMPANY qo JUN i3 ~ll: O8 June 11, 1980 L-80-178 Mr. James P. O'Reilly, Director, Region II Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission +o-s~w 101 Marietta Street, Suite 3100 Atl anta, Georgi a 30303

Dear Mr. O'Reilly:

Re: RI I: JPO 50-335 IE Bulletin 80-05 Florida Power 8 Light Company has reviewed the subject bulletin and has the following response:

1. Tanks with cover gas which can be valved to contain RCS water are provided i n Table l. Also provided are the tank internal design pressures, their system designations and volumes. As requested in the bulletin, our evaluation will be limited to low pressure tanks, or tanks with an internal design pressure of 15 psig or below. Thus, based on Table 1, only the RWMS Holdup Tanks and Refueling Water Storage Tanks (RWST) are considered. Adequate measures have been taken to protect these tanks against vacuum conditions that could result in tank damage.

These measures are discussed in our response to item 2 below.

2. The systems reviewed in item 1 included the Reactor Coolant System, the Chemical Volume and Control System, the Safety Injection System, and the Radioactive Waste Mangement System. As indicated in item 1, the only tanks requiring further consideration are the RWMS holdup tanks and RWST-The four RWMS holdup tanks are each designed in accordance with ASME Section VIII Division 1-and have an external design pressure of 2 psig.

There are three pumps connected to the tanks, each with a run out flow of ~130 gpm for a ccmbi ned total of ~390 gpm. Thus, the maximum expected flow out of a given RWMS holdup tank would be +390 gpm or 52 SCFM. The tanks have a nitrogen cover gas system which maintains a 1 psig over pressure. The cover gas system utilizes one Model 95L Fisher pressure regulator (1 psig outlet setting and normal N2 inlet pressure of 10 psig) feeding a 3 inch supply header to all four tanks. Calculations were perfomIed to determine the Nq flow rate available (assuming worst case pressure drop) to a given RWHS holdup tank when at an internal pressure of 12.7 psia. The calculated N2 flow rate to the tank was 57 SCFM.

This value is in excess of the maximum expected outflow of 52 SCFM which would preclude vacuum conditions which could result in tank damage. This calculation is conservative as normal operating procedures would preclude pumping from one tank with all three pumps.

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I PEOPLE... SERVING PEOPLE 4

Mr. James P. O'Reilly Page 2 The venting capacity of the RWST was calculated assuming all pumps which take suction from the tank are operating at maximum flow simultaneously. The tank was shown to have a safety factor of 7.34 in its venting capacity.

Based on the above discussion, the exi sting measures for vacuum protection at St. Lucie Unit 1 are adequate and no further modifications are required. As a general note, the St. Lucie/CE 1'etdown system degasses the RCS water through the flash tank prior to reaching the RWMS holdup tanks and clean N2 is used for cover gas. Both measures significantly reduce the consequences of tank rupture. The Westinghouse units referenced in the bulletin do not degas the water before it enters the holdup tank and most Westinghouse units utilize a waste gas decay tank as cover gas supply.

Very truly yours, Robert E. Uhrig Vice President Advanced Systems 8 Technology REU/MAS/cph cc: Director, Office of Inspection and Enforcement Harold F. Reis, Esquire

TABLE 1 TANK *SYSTEM QUANTITY VOLUME DESIGN PRESSURE PS IG (Gal) INT/EXT

1. Pressurizer RCS 1,570 100/15 Quench Tank (QT)
2. Reactor Drain RWMS 1,600 25/15 Tank (RDT)
3. Volume Control CVCS 4,700 75/15 Tank (VCT)
4. Flash Tank RWMS 400 70/15 (Fl')
5. CVCS Holdup RWMS 40,000 10/2 Tanks (HUT) (each)
6. Ref uel i ng SIS 525,000 Atmospheric Water Storage Tanks
  • RCS -- REACTOR COOLANT SYSTEM AND AUXILIARIES CVCS - CHEMICAL VOLUME AND CONTROL SYSTEM RWMS - RADIOACTIVE WASTE MANAGEMENT SYSTEM