ML19269D100
| ML19269D100 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 02/22/1979 |
| From: | Roe L TOLEDO EDISON CO. |
| To: | Baer R Office of Nuclear Reactor Regulation |
| References | |
| 2-140, NUDOCS 7902270322 | |
| Download: ML19269D100 (2) | |
Text
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TOLEDO 2
%s EDISON Docket Nos. 50-500 LOWELL E. ROE 50-501 vu pre.o.m Facilmes Development (419: 259 5242 Serial No. 2-140 February 22, 1979 Director of Nuclear Reactor Regulation Attn:
Mr. Robert L. Baer, Chief Light Water Reactors Branch No. 2 Division of Project Management U.S. Nuclear Regulatory Commission Washington, D.C.
20555
., ear Mr. Baer:
At the 220th ACRS meeting on August 3, 1978, during discussion on the application for construction permits for Davis-Besse Nuclear Power Station Units No. 2 and 3, a question was asked Toledo Edison Company on the effect of recycling of liquids on in-plant exposures due to the build up of tritium. See Page 96 of the transcript where Dr. Lawrowski requests that we supply information to the Staff. The attachment shows the results of our study on this subject.
Yours very truly, LER:RES Attachment dh d/1 cc: Chairman, Advisory Committee on Reactor Safeguards U.S. Nuclear Regulatory Commission lh Washington, D. C. 20555 k
THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OHIO 43652 7902P.7097
ATTACHMENT TO TOLEDO EDISON COMPANY LETTER DATED FEBRUARY 22, 1979, SERIAL NO. 2-140 TRITIUM EXPOSURE ANALYSIS In response to a question asked at the 220th ACRS meeting of August 3, 1978, the effect of recycling of liquid radioactive waste on in-plant occupational exposures due to the resultant build up of tritium has been examined, and a brief analysis has been performed for zero and one hundred percent recycle cases.
Since tritium is a weak beta emitter, tritium concentrations in piping and equipment throughout the plant have a relatively insignificant effect on exposures due to direct radiation.
The predominant source of tritium exposure is expected to be in areas where there 1.s significant evaporation of tritiated water such as the spent fuel pool area and the containment (during refueling operations. )
It should be noted that even in these areas, the major contribution to the tritium dose is inhalation rather than direct radiation. Equilibrium tritium concentrations are, to some extent, self-limiting since even for a mrximum case of one hundred percent recycle the plant would still lose tritium due to evapor-ation.
In the past four years, two studies were performed by our architect /
engineer, for other PWRs, to determine in-plant tritium concentrations and tritium exposures resulting from recycling of liquid radioactive waste.
These studies indicated an equilibrium tritium concentration in the spent fuel pool and refueling tool of approximately 2.0 pCi/cc (based on a tritiun production rate of 1470 Ci/yr for one unit) for the one hundred percent recycle case.
For the zero percent recycle case, in which all liquid radioactive waste (including shim bleed) is discharged after processing, it is conservatively estimated (based on the same tritium production rate) that the equilibrium tritium concentration in these pools would be less than 0.2 pCi/cc.
Applying these concentrations to the Davis-Besse plant, and using conser-vative assumptions, analysis shows that fcr the range of zero to one hundred percent recycle, tritium doses in the spent fuel pool area would vary between 0.68 and 6.8 Man-rems per year for each unit, and in the containment this variance would be between 1.66 and 16.6 Man-rems per year for each unit.
Summing these contributions results in an in-plant occupational tritium exposure range 2.34 to 23.4 Man-rems per year for each unit corresponding to zero.o a hundred percent recycle.
This r; relatively small when compared.o the 200-400 lbn-rems per year exposure typical for operating plants.
Jh d/9