ML19256F279
| ML19256F279 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/13/1979 |
| From: | Wilson R METROPOLITAN EDISON CO. |
| To: | Vollmer R NRC - TMI-2 OPERATIONS/SUPPORT TASK FORCE |
| References | |
| FOIA-80-301 GQL-1506, NUDOCS 7912180428 | |
| Download: ML19256F279 (4) | |
Text
{{#Wiki_filter:. s [ ".~~ ':* Metropolitan Edison Company m' ] k* f { Post Office Box 480 ([ ~ {' " ' Middletown, Pennsylvania 17057 su 717 9444041 Writer's Direct Dial Number December 13, 1979 GQL 1506 DII Support Attn: R. Vollmer, Director U. S. Nuclear Regulatory Commission Washington, D.C. 20555
Dear Sir:
Three Mile Island Nuclear Station, Unit 2 (TMI-2) Operating License No. DPR-73 Docket No. 50-320 BWST Tech. Spec. Modification Enclosed please find justification for reducing the minimum Borated Water Storage Tank (BWST) volume from 350,000 gallons to 100,000 gallons. Please note that the water currently contained in the Unit 2 BWST is "non Unit 2 accident" water and has been sampled. These samples contain radionuclide concentrations and ratios indicative of pre-accident Unit 1 Spent Fuel Pool water which was presumed to be the primary source of this water. Therefore, it is requested that the BWST be drained to within allowable limits and that EPICOR II processed and borated water be used to fill the BWST. Your prompt attention to this matter would be greatly appreciated. 'ncer ly, -fl k L R. F. Wilson Director ntI-2 RFW:LWH: hah Enclosure cc: D. Brinkman J. T. Collins 1608 260 Aco! sgf ve~cccoa, Ec son cen:2,y s a ';ercer core cere a:;uc c u u es s, rem [ 7912189
The proposed Technical Specifications currently limit the minimum Borated Water Storage Tank (BWST) inventory to 350,000 gallons (Reference Page 3.1-1 paragraph 3.1.1.1 TMI-2 Tech. Spec., Appendix A) which was based on the core decay heat rate in June 1979. Extrapolated calculations for a December 14, 1979 core decay heat generation rate show that there is at least three days core cooling capacity with a minimum of 100,000 gallons (see Appendix A). Three days would allow sufficient time to provide borated water to the BWST from other water sources. The alternatives which would be used prior to cooling water from the BWST are described in Emergency Procedure 34 (EP-34). The existing Unit II BWST inventory is approximately 460,000 gallons. Upon approval of the above proposed changes we would commence transfer of approximately 360,000 gallons to Unit I BWST and EPICOR I consistant with necessary clean up and processing restrictions. This would leave a minimum of 100,000 gallons of borated water in the Unit II BWST at all times. Refill /boration could then commence from EPICOR II at a controlled but less critical pace. (EPICOR II effluent would, of course, be checked for compatability with BWST chemistry requirements and doped with H B03 to meet the 3,500 3 ppm Boron minimum requirement prior to being pumped into the Unit II BWST). Use of the Unit II BWST for storage of EPICOR II effluent will minimize the total quantity of processed water which must be disposed of through the ultimate disposal method finally adopted for TMI-2. 1608 261
a ~% APPENDIX "A" Minimum Required BWST Inventory ~ Design Case: Provide three days supply of cooling water for a break in the Reactor Coolant pressure boundry on the reactor outlet piping at or below t the elevation of the Decay Heat letdown line at its' connection to the hot leg. Core decay heat to be removed thru sensible heating of Reactor Make-up (no steam cooling credit). Cooling path would be from the BWST thru a Make-up pump to a Reactor cold leg; thru the core and out the break to the Reactor Building sump. 6 Decay Heat (December 14, 1979) 1.06 x 10 BTU /hr. BWST maximum te=perature 90*F; Break outlet te=perature (212*F assume 200*F 6 Required feed rate = q [Decav Head 1.06 x 10 BTU /hr. = h'201 - h'90* 110 BTU / ibm 9636. LBM/ttr. _ m feed = or 19.34 gpm 3 days at 19.34 gpm is 83,555 gallons total feed BWST internal diameter is 37' - 6" and the centerline of the 20" discharge nozzle is 2' - 2" above the bottom of the tank (Ref. Pittsburgh - Des Moines Steel Co=pany Drawing E-2, Contract 11011; TMI File #7-34-0102). Therefore at S261 gal /ft the dead storage is less than 16,500 gallons.
- and, 16500 gallons dead storage
+ 83500 gallons 3 days inventory 100,000 gallons minimum BWST inventory For reference this is equivalent to 12.1 feet of BWST level. 1608 262
Appendix "A" page 2 However, to account for possibic error in the level instrumentation string, a safety factor must be added to this value to find the set-level. The instrumentation string has an overall accuracy better than 2% full scale and was calibrated for Boric Acid solution with a specific gravity of 1.004. At 3600 ppm (B) the specific gravity of our solution is approximately 1.008. The correction factor to assume that at least 100,000 gallons are in the tank is. 1.008 (0.02) 56, = 1.12' BWST TECH. SPEC. MINIMUM LEVEL SEQULD BE 12.1'+ 1.l' = 13.2 feet 1608 263}}