audience. Comment on this flexibility, please. Can CFR 20.160E allow the aec to limit discharges below mpc when the mpd is exceeded in a sample of food?

auerbach. The flexibility, as I understand it, is partly based on the nature of the population that is to be exposed, or may be exposed, to the radiation. I should make the point that under the recommendation of icrp, the basic limitations are the dose to the population; if the limitation of exposure for the general population is.17 mrad, that governs and over­rides the mpc’s.

audience. Does heat have any proved effect on algal growth? Could you name specific studies? Are there any other studies under way?

brungs. Even without citing sources — which would take research because I’m a fisheries biologist and not an algologist — I can say that any biological process, such as metabolism or growth, is affected by tempera­ture. Within limits, as the temperature rises, the rate of these biological processes would increase also, and therefore, algal growth would increase. Obviously, if the temperature goes beyond too high a level, the algae can actually be killed off. The growth will increase, then start decreasing, and eventually, mortality will occur. For specific references, I’d prefer to con­sult my files rather than rely on memory.

audience. What is the current state of knowledge concerning the concentration of tritium in the environment and in body tissue?

tamp lin. I know that there has been some discussion of the possi­bility that tritium is one of the radionuclides that will concentrate when moving up through food chains to man. This question came up with re­spect to the Lake Cayuga reactor. We heard about possible concentration in the food chain there, and we looked into it. Our opinion was that the question being asked could be resolved if someone made a detailed study on the concentration of deuterium over this period of time. Tritium has a mass of three, compared to hydrogen’s one, and will react at a rate differ­ent from hydrogen within the various biological systems. The difference in the reaction rates between tritium and hydrogen could cause tritium to concentrate. When we looked at the data that was available — deuterium to hydrogen ratios and tritium to hydrogen ratios — we concluded that tritium probably would not be concentrated in man by more than a factor of three. The data were not sufficient to indicate that tritium would not be concentrated by as much as a factor of three.

audience. Great emphasis is placed on elucidation and anticipation of problems and finding solutions. In your evaluation, is the aec providing the public with adequate safeguards in plants presently built? Would the Minnesota Pollution Control Agency limit on plant operation improve or make more hazardous plant operation at Monticello?

bray. I definitely endorse the degree of public safety being provided by the reviews of the aec based on my experience with the applications that we have brought forth with our clients. I have always been impressed with the detailed evaluation techniques, the multitudinal questions, and the meticulously detailed review of the dockets of the applications that have been made. First, one goes in with a preliminary safety analysis re­port and then amendments are made. The amendments are based upon questions raised by the regulatory staff and answered by the applicants. The technical level of these questions and answers is a manifestation of the high degree of safety that is sought.

With respect to the second question, I don’t think it is a question of improving or making plant operation more hazardous. It is a question of using different limits than are now invoked for plants being operated. It is a question of whether the limits can be complied with or whether the means by which they could be carried out should be made clearer. These limits are not yet agreed upon.

tamplin. Should the Minnesota limits become law in the state of Minnesota, would you be able to meet them?

bray. There is still a question of fully appreciating what each part of the limits means. There are questions with respect to measurement tech­niques and procedures. I’m not fully familiar with the limits since they are still the subject of discussion. Until it is clear what is being requested, I’m not able to comment on whether we could meet the mpca limits.

audience. Mr. Tamplin, would you please show the calculations which allow you to make the statement about dose rates you made at the start of your paper—that mpc for air for one year for 13TCs gives a dose of 2,555 rads to children?

tamplin. The mpc for air is 2 X Ю9 ftCi/ml. Since there are 10® ml in a cubic meter, we next get 2 X Ю-3 /лСі/m3. If this concentration is maintained for a day, 24 hr, we end up with 48 X 10’8 /лСі hr/m3. There have been a number of experiments performed which have measured the concentration in air and then measured the concentration that gets de­posited out of the air. From that comes a ratio called deposition velocity; by assuming that cesium is on small particles in the atmosphere (which is likely), we arrive at a deposition velocity of 17 meters (m) per hour. When these two numbers are multiplied, the deposition is.82 ^Ci/m2. Starting with this deposition on forage and considering the facts that a cow eats over 45 m2 of forage per day, that 1 per cent of the cesium she takes in goes out in each liter of her milk (1 per day), and that cesium has a half-life in the child’s body, the result is that a deposition on forage of.12 /tCi/т2 is equivalent to 1 rad received by a child drinking 1 liter of milk per day. This kind of information is tabulated for all the radionuclides listed in the chart of nuclides (UCRL 50163, Pt. IV, p. 86).