ML19308D065
| ML19308D065 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/20/1980 |
| From: | Wilson R METROPOLITAN EDISON CO. |
| To: | Jay Collins NRC - TMI-2 OPERATIONS/SUPPORT TASK FORCE |
| References | |
| TLL-068, TLL-68, NUDOCS 8002270330 | |
| Download: ML19308D065 (3) | |
Text
6 Metropolitan Edison Company gj ff ()
Post Office Box 480 y
Middletown, Pennsylvan,ia 17057 717 044 4041 Writer's Direct Dial Number February 20, 1980 TLL 068 TMI Support Attn:
J. T. Collins, Deputy Director U. S. Nuclear Regulatory Co::: mission c/o Three Mile Island Nuclear Station Middletown, Pa.
17057
Dear Sir:
Three Mile Island Nuclear Station, Unit II (TMI-2)
Operating License No. DPR-73 Docket No. 50-320 Processed Water Storage Tanks As discussed in our letter of January 24, 1980 (TLL 029), enclosed please find the Tank Venting Analysis on the subject tanks.
The controlling isotope for this analysis was determined to be tritium. The release rate was conservatively based on filling the tank at a flow rate of 2,000 gpm, which resulted in a tritium release rate of 4.59pci/sec.
The analysis resulted in concentrations that are well within the limits specified in Appendix B to 10 CFR 20.
The results of these analyses and the limits specified in Appendix B to 10 CFR 20 are given below.
Calculated Concentration 10 CFR Part 20 Appendix B Allowable Offsite Unrestricted Areas 3.08E-11pci/cc 2.0E-7 A i/cc Occupational Workers 1.02E 7 jaC1/cc 5.0E-6jeCi/cc Sincer ly,
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R. F. Wi son 03 Director, TMI-II 0
RFW:LWH: hah Enclosure g\\
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R. Vollmer 8002270 33o Me:roco!itan Ecson Company is a Member of the General Public Utilities System
e ATTACH?'ENT 2
'O TANK VENTING ANALYSIS _
Described below is the analysis perforced to determine the tritium concen-the site boundary and a worker occupational concentration adjacent tration at to the Processed Water Storage Tank (PWST) resulting from tank venting.
isotope.
Tritium was the only isotope considered due to it being the predominant The concentration of tritium in the water (1.05 pCi/ce) was based on 2,000 Ci.
of tritium in 500,000 gallons of water. The relative humidity in the tank to be filled was assumed to be 100 percent.- The evaporation rate of tritium was assumed to be equal to that of water, which results in the relative concen-This results tration of tritium in'the vapor being the same as in the liquid.
in a tritium concentration in the vapor of 3.64E-5 pCi/cc.
The flow rate into the tank was assumed to be 2,000 gpm, this being the limiting flow rate based on the tank vent capacity specified in the tank specification.
flow rate to a volu=e of vapor displaced and using the tritium Converting this concentration in the vapor, the release rate for tritium was calculated to be 4.59 pCi/sec.
Using the average annual X/Q of 6.7E-6 sec/m, the offsite concentration was 3
calculated to be 3.08E-11 pCi/ce.
This is well below the limit of 2.0E-7 pCi/cc specified in Appendix B to 10 CFR 20.
For the arker concentration a X/Q was calculated by using the low wind speed of 2.7 m/sec (6 mph) and an isopleth of Kc = 10.
This resulted in a X/Q of 2.22E-2 sec/m3 Using this X/Q and the flow rate of 4.59 y:Ci/ce, the tritium concentration adjacent to the tank was calculated to be 1.02E-7 pCi/ce.
This is below the limit of 5.0E-6 pCi/cc specified in Appendix E to 10 CFR 20.
Since the resultant tritium concentrations ar'e below the limits specified in Appendix B to 10 CFR 20, the present venting design for the tanks is considered satisfactory.
The following comments are offered regarding the X/Q in the worker concentration The X/Q in this calculation was determined assuming the tank was calculation.
in an open area.
In reality, this is not the case.
However, the X/Q calculation; In addition, did not consider building vake effects from surrounding senceures.
When all of these are con-the Ke = 10 is a conservative value for this case.
sidered, the X/Q used for the determination of the worker concentration is considered a realistic, yet conservative value.
We would point out three significant areas where both of the concentration The first of these is that the anticipated tritium results are conservative.
The concentration is well below the 1.05 pCi/cc assumed for the analysis.
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second area deals with the flow rate of 2,000 gpm into the tank.The transfer pu=ps This value is for the purpose of sizing the tank vent.
been sized but are expected to have no more than half this flow, i'.e. the transfer pumps would be no greater than 1,000 gpm, which would be.the upper The third area concerns how often there would be bound for the flow rate.
It is anticipated that cost of the time there
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flow to one of these tanks.
During this time, the tritium venting from will be no flow to these tanks.
h the tank would be due only to evaporation, which is significantly less t an the assu=ed flow rate.
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