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given in Title 10, Chapter 1, Part 20, Code of Federal Regulations, Re- vised 1959 (proposed). POTENTIAL SOURCES OF RADIOACTIVE WASTES Of all the unwanted radioactive byproducts, or wastes, produced in the operation of a nuclear reactor, the fission products comprise the bulk. Under present and contemplated design, these fission products would be contained largely in the spent fuel elements. Additional wastes result from the induced activity of corrosion products in the primary coolant, together with small amounts of fission products which may be transferred to the primary coolant as a result of minor failures in the cladding of the fuel elements. The amount of radioactive materials in the primary coolant is maintained at relatively low levels by use of a bypass purification system resulting in the accumulation on ion exchange resins of corrosion product activity, and a considerably smaller amount of fission product activity. The greater part of the fission products is removed from the ship in the spent fuel elements at the time of refueling. The possible ultimate fate of such high level wastes is beyond the scope of this re- port. It is, however, our basic assumption that these high level wastes do not enter the marine environment through normal operation of a nuclear-powered ship. Only in the case of a highly improbable maxi- mum credible accident could any portion of these materials enter the marine environment. The potential sources of radioactive wastes which might be dis- charged to the marine environment from nuclear-powered ships are, then: (a) the expansion volume of primary coolant during warm-up of a pressurized water reactor; (b) operational leakage from various com- ponents of the primary and auxiliary systems, and wastes from the lab- oratory, from sampling, from equipment decontamination, and shower and laundry wastes associated with the reactor plant; (c) ion exchange resins which remove corrosion products from the primary coolant; and (d) contaminated solid materials. AMOUNT AND COMPOSITION OF WASTES The amount and composition of radioactive wastes cannot be pre- dicted accurately for all potential marine reactors. In order to have some reasonable basis for evaluation, data for the proposed N.S. SAVANNAH, obtained from the report of the Maritime Administration entitled "Waste Disposal Considerations in the Nuclear-Powered Merchant Ship Program" (January, 1959), have been employed as rep- resentative of the composition and amount of "typical" potential radio- active wastes from a nuclear-powered merchant ship. In addition, actual operating data from the nuclear-powered sub- marine NAUTILUS have been made available in the report "Radioactive Waste Disposal from U. S. Naval Nuclear-Powered Ships" (January, 1959) presented for inclusion in the record of the public hearings on
industrial radioactive waste disposal held by the Special Subcommittee on Radiation of the Joint Committee on Atomic Energy, Congress of the United States, 27 January to 3 February, 1959. These data also have been utilized by this working panel. The major source of potential liquid waste is the primary coolant. For the SAVANNAH,* after 50 days of operation during which a single ion exchange bed has been utilized for by-pass clean-up, and assuming 1530 grams of exposed fuel, it is estimated that the concentration of ac- tivity of the significant isotopes in the primary coolant will be about 8 x 10'2 uc/ml, of which the greatest amount will be Cr 51, Co 60, Fe 55, and Ta 182. Strontium 90 is estimated to have a concentration in the primary coolant water of 1.4 x 10'7 The expansion volume during reactor warm-up is estimated to amount to 290 ft', or 8.2 x 10^ ml. Thus during each warm-up a total release of about 6.8 x 10'1 curies would occur. Cr 51 would contribute about 0.4 curies, while Co 60, Fe 55 and Ta 182 would contribute about 0.1 curie each, and Sr 90 would contribute about 1 x 10'6 curies per warm-up to the potential liquid effluent. Leakage and other minor sources of liquid waste might contribute 100 gals/day, or 3.8 x 105 ml, of liquid effluent of about the same activity as the warm-up water. This would be equivalent to a total activity per day of 3.0 x 10'2 curies. Assuming that each vessel had an average of two warm-ups per month, the total potential activity in the liquid wastes from one ship during one year's operation would be 16 curies from warm-up and 11 curies from leakage and other minor sources. The ion exchange resins used in the by-pass clean-up of the pri- mary coolant would contain far greater activity than that present in the primary coolant itself. It is estimated that in the present merchant ship design these resins, after 50 days of operation, would contain a total activity of about 400 curies, with Cr 51, Ta 182, Co 60, and Fe 55 each contributing about 100 curies. Assuming a change of resin every 50 days, the total activity released per ship per year from this source would be 2900 curies. It is estimated in a later section of this report that 300 nuclear- powered ships of all nations will be in service by 1975. These 300 ships would then potentially release to the marine environment approximately 2500 curies per year from expansion water, some 3400 curies per year from leakage and other minor sources of liquid wastes, and some 9 x 105 curies per year from the ion exchange beds. 'Since completion of this report, subsequent re'evaluation of the probable character and activity of the primary coolant and the ion exchange resins has been issued by the Oak Ridge National Laboratory (1959). While this ORNL report includes somewhat different values for the activity in these potential wastes, the general conclusions arrived at here remain unchanged.
According to the report "Radioactive Waste Disposal from U. S. Naval Nuclear-Powered Ships", the actual operating results of the U. S. S. NAUTILUS and the U. S. S. SKATE have produced radioactive wastes considerably less, both in intensity of activity and in amount, than those predicted in the Maritime Administration's report for the SAVANNAH. The average gross activity of the primary coolant of the NAUTILUS, 15 minutes after sampling, was 5 x 10'2pc/ml. However, the bulk of this activity was associated with Mn 56 (2.5 hr half life) and F 18 (1.9 hr half life). The gross activity 120 hours after sampling has averaged 3 x 10'' uc/ml. The measured activity of Co 60, Fe 59, and Ta 182 has averaged 5.7 x 10'6 , 1.5 x 10'4, and 7.3 x 10'3 uc/ml re- spectively. Fe 55 apparently does not occur in measurable quantities in the primary coolant of the NAUTILUS. The expansion volume on warm-up for the NAUTILUS is much less than that predicted for the SAVANNAH, averaging about 500 gals (67 cubic feet). The maximum activity on the spent ion exchange resins in the NAUTILUS, and the rate at which these resin beds require re- placement, are likewise much less than the corresponding figures for the SAVANNAH. The total activity on the spent resin beds is reported to be no more than 12.5 curies, with the bulk of the activity (some 10 curies) resulting from Co 60. The beds have required replacement about once every six months. During each warm-up involving the average discharge of 67 ft3 or 1.9 x 10Â° ml, the NAUTILUS then releases approximately 9.5 x 10'2 curies (measured 15 minutes after sampling). Co 60, Fe 59, and Ta 182 would contribute 1.1 x 10'5 curies, 2.9 x 10"* curies, and 1.4 x 10'2 curies, respectively. Assuming two warm-ups per month, the total activity in the expansion volume liquid wastes from the NAUTILUS during one year would be about 2.3 curies measured 15 minutes after sampling and 0.14 curie measured 100 hours after sampling. In comparison with these amounts, the activity in the fission prod- ucts contained in the spent fuel elements is quite large. Thus the fis- sion products in the fuel elements from a 60 MW reactor which had been in service for one year on a nuclear-powered ship would amount to over 107 curies. It has been stated that the vast majority of the fission product wastes will be stored on land, after chemical separation from unused fuel and useful by-products. However, even a small fraction of this activity could be significant if released in coastal areas. Release of activity to the coastal environment by land based nuclear installations, particularly chemical processing plants, may be difficult to avoid. Thus, under a carefully controlled program designed to limit the re- turn of activity to man to a safe level, the Windscale Works in England is authorized to release over 105 curies per year into the coastal waters of the Irish Sea. The major part of the safe capacity of these inshore areas should then be reserved for land based operations, since nuclear-powered ships could conceivably delay discharge of wastes until outside such areas.