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TABLE 1.--Estimated cost of reprocessing power-reactor fuels in plants of various designs
Phillips small plant (2)
Davison Chemical (3).
du Pont (5)
AEC reference plant (7).
*Includes fuel fabrication. ** Actual charge from Ref. 7 will average $20/kgU for a large reactor.
TABLE 2.-Investment and operating costs for small reprocessing plants
The unit costs of reprocessing from Table 1 are plotted in Fig. 3 as a function of rate. The large-scale plant operating continuously at 10 tonnes U/day is the most economical; but as the large plant is sealed down, its unit costs go up. On the other hand the small plant can be scaled up to 0.3 tonne U/day, at which rate the reprocessing cost is the same as for the larger plants or the AEO. reference plant at 1 tonne U/day. The region between 0.3 and 1.0 tonne U/day: can be bridged by building a second and then a third small plant of 0.3-tonneU/day capacity each. As the load builds up beyond 0.3 tonne U/day, the cost will vary between a high of $40/kg U and $20/kg U, the $20 value occurring at 0.3, 0.6 and 0.9 tonne U/day. These unit costs for processing to uranyl nitrate: can be related to power costs by the fact that for the Dresden reactor $21/kg U is equivalent to 0.30 mill/kwh.
If small batches of fuel are put through a large plant on an independent-job, basis, plant holdup and turnaround time raise the unit cost of reprocessing to nearly the same value as for the small plant (9). It is this very problem of handling different fuels from twenty different customers that has confronted the Eurochemic reprocessing facility and reduced its planned actual fuel reproc, essing time to ~150 days/yr. Utility-company financing
If one vises the economics of the electric-generating companies, whose capital structure consists of a common-stock equity of 35% and 65% bonds and preferred stock, the return to the common stockholder from a small plant can be calealated as in Table 3. Three unit charges are assumed, a charge of $21/kg U is equivalent in the power-fuel cycle to 0.30 mill/kwh for the Dresden reactor 88 originally designed; $21/kg U is also the corresponding cost from the AEC
reference plant (10). Thus the return on the common-stock equity in the reprocessing plant would increase linearly with the charge assigned to reprocessing. There might be some question as to whether a reprocessing plant can be financed on the same long-term bases as a modest-interest power-generating utility, whose financial structure derives from the small risk and long-term stability of power plants. The question would be whether the life and ap-: plicability of the small-scale reprocessing plant would justify such long-term. bonding conditions.
TABLE 3.-Profit from Small Plant* with Power-Company-Type Amortization
*$4.77-million capital investment; reprocessing Dresden-reactor-type fuel at rate of 272 kgU/day for 270 days/yr.
Short payout periods
Chemical and petroleum companies usually calculate new ventures on much shorter payout times than those shown in Tables 1 and 3. So we have calculated; the profit from a small-scale plant as a function of reprocessing charges to the utility company, on the basis of 15-yr amortization and an interest on loans of 1% of the investment; in this case 80% of the capital is furnished by the stockholders and the rest is from loans. Table 4 shows that this results in a payout range of 13.1-2.3 yr for unit charges of $21-70/kg U. In 1955 a representative payout for: new investment was 6.7 yr for the petroleum industry, 6.0 yr for the basic-chemical industry and 7.4 yr for the process-chemical industry (11).
Variable factors influence payout standards for business ventures. High-risk projects might require payouts of less than a year. In this regard nuclear-fuel reprocessing does not fit any established pattern and presents new and unique considerations for evaluating what constitutes an acceptable payout period. For instance there is a trend toward furnishing power companies a "package fuel service" in which a company or group of companies furnishes the uranium, fabri.. cates the fuel, reprocesses the spent fuel and reconstitutes the recovered values., Under these conditions one link in the chain might be allowed to produce a lower profit to obtain the over-all business. On the other hand if several competing companies handle most of the fuels in this manner, the total reprocessing load will have to be divided between at least two or three companies and for this: reason we believe several small plants would be more appropriate now thani å single large plant.
Other aspects of reprocessing that can affect the profit are the credit from locating the plant close to areas of power generation (so that spent-fuel shipping charges are lower) and the possibility of extra income through recovering spe; cific or gross fission products for new uses (12). The cost or shipping irradiated fuel under the AEC reference-plant scheme for six major nuclear power reactors i has been estimated to average 0.20 mill/kwh (10). À transportation saving of
0.05-0.15 mill/kwh might be credited to the reprocessing cost if several small reprocessing plants were strategically located with respect to the power-generating industry. Possible locations of several small plants are noted in Fig. 1, but the final choice will depend on many factors (such as state and federal control and industrial criteria, as well as transportation). Available load and plant size
The fuel load is the major factor in the economics of fuel reprocessing. Plants should be sized to an existing load or to a load that will be available within a period of significance to the operator. From an analysis of power reactors and their fuel discharge it appears that ~100 tonnes U/yr will be the fuel load for the next five years from U.S. private and government reactors using slightly enriched UO, fuel in stainless-steel or Zircaloy tubes ; foreign load might be 170 tonnes U/yr, but this can not be relied on. One small-scale plant could handle 74 tonnes U/yr at 272 kg U/day. Two or three small plants would provide means for private industry to enter the business without excessive risk in a changing market and with a chance of modest but increasing profits and also could provide the competitive stimulus necessary for healthy evolution of the nuclear industry. Highly enriched cores
Although it is not normally regarded as part of the private nuclear power program, enriched uranium fuel also should be examined as a potential load for a single small-scale reprocessing plan. The 68-kilogram-U/day Phillips small plant (2) could be redesigned and operated safely on 90-percent enriched uranium fuel alloyed with aluminum and possibly zirconium at 7 kilogram U23/day. The source of these fuels wolud he numerous test and research reactors and the seeds of Shippingport-type reactors. A quick view of soures of enriched alloy fuels in the United States indicates an annual load of 1,000 to 2,000 kilogram U23 by 1966, which is well within the capacity of a small plant.
The cost of reprocessing highly enriched uranium-aluminum fuel can be calculated according to the AEC reference plant figures. Batch size is of prime importance in calculating total cost. The processing rate for enriched uraniumaluminum alloys now is based in the reference plant on 400 kilogram alloy/day. If one assumes an ETR alloy composition of 4.5 w/o uranium, then the reference plant throughout is 18 kilogram U/day or 167 kilogram U235
*/day, based on 93 percent enriched uranium. The reference plant annual costs for 1,000 kilogram U28/ year in plant batches of 50, 100, and 1,000 kilogram U* are $2.04, $2.04 and $1.16 million, respectively. The annual cost of $1.293 million for the small plant when operating at a rate of 69 kilogram/day (of low-enriched uranium) should be about the same as the operative costs to process 3.7 kilogram U238/day (1,000 kilogram U23$/year) from uranium-aluminum alloy; on this basis the small plant charges at $1,293/kilogram U235 would be more economical than the reference plant, except when the entire year's load is processed in the reference plant in a single campaign. Although a single continuous campaign is feasible, it would involve problems of storing the fuel during the year and of providing shipping facilities.
Because AEC reference plant charges should be considered as somewhat arbitrary and of only interim applicability, a direct measure of the cost of reprocessing uranium-aluminum alloy in AFC facilities would be a better basis on which to compare the charges of a small-scale plant with Government recovery costs. The cost of enriched fuel reprocessing as performed at the Idaho Chemical Processing Plant has been described (13). We have assigned a batch process operating at 9 kilogram U/day from highly enriched uranium-aluminum alloy a capital cost of $9.2 million and an annual operating cost of $2 million. If the fixed charges are 16.9 percent of capital cost, the total annual cost is $3,550,000, or $1,410/kilogram U28 on a basis of operating 300 days/year. Even if we neglect the fact that 1,000 kilogram U235 / year of fuel would not keep a plant running continuously for 300 days at 9 kilogram U/day, the reprocessing cost of $1,410/ kilogram U236 is slightly higher than the $1,160/ U235 for a continous 1,000-kilogram-U235 run in the AĚC reference plant, and lower than the $2,040 for smaller batches.
TABLE 4.- Payout from reprocessing Dresden reactor fuel in a small plant* at
different unit costs (petroleum company financing)
*$4,770,000 capital investment; reprocessing 272 kilogram U's per day for 270 days per year.
DESIGN FEATURES OF A SMALL REPROCESSING PLANT Although large reprocessing plants at Hanford and Savannah River are re covering plutonium from irradiated natural uranium, the concept of a small radiochemical plant is not new and untried. Related technologies are known and well developed. Perhaps the most significant existing small plnat is ré covering radiobarium from 2-day-cooled MTR fuel elements (15, 16).
This small plant, a unit that is located at the Idaho Chemical Processing Plant, has recovered routinely more than 1.5 million curies of purified Ba? in batches of up to 50,000 curies. The plant is in a single shielded cell 16 X 17 X 36 ft. and has a cask-entry and -unloading station, dissolver, off-gas scrubber, two remote and cooled centrifuges, numerous hold tanks and three miles of piping. The short half-life Ball requires rapid processing.
We have in mind small plants that would recover uranium and plutonium from spent low-enrichment fuel elements at a rate of 0.068-0.3 tonne U/day. Design details of a small 0.068-tonne-U/day plant have been described (2). In addition, Allis-Chalmers has proposed a small-scale processing and fuelfabrication plant in Italy for CNEN. The table in this box compares major features of small and large plants.
Although we originally considered the small plant as a single-purpose plant that might process fuel from one or more reactors of the same type, by using a chop-leach headend the plant could process fuel rods whether they were clad in Zircaloy-2 or stainless steel. In most cases the equipment would be critically safe by geometry. The core and blanket of a reactor could be handled successively. Obviously there would be no reason to make each sthall plant fully universal, which probably would be required of a large multipurpose plant. Although development studies at Oak Ridge and ICPP have shown ways in which several fuel types can be handled by one process, the process choice would depend partly on the type of fuel being favored by the "package fuel service" of the reprocessing company.