Fuel-cycle costs

To achieve a fuel management scheme with the lowest fuel cycle cost consistent with the current thermal and material performance limits, the following parameters are selected (l)a fuel cycle incorporating uranium/thorium (2) a fuel lifetime of four years (3) an average power density of 8.4 W/cm3 and (4) a refueling frequency of once a year. 

Zabunoglu, O.H. Ozdemir, L. Purex co-processing of spent LWR fuels Comparative fuel cycle cost analyses, Ann. Nucl. Energy 32 (2005) 137-149. 

Fuel cycle costs in nuclear power stations (January 1995, PtVkWh) ... 

Figure 3.14 shows the total steady-state fuel-cycle cost for an interval of 1.0 year between refuelings as a function of feed enrichment for batch fractions, /, of 5, j, and j. The batch fraction is defined as 1 In, where n is the number of fuel zones. Also plotted in this flgure are levels of constant energy production (E) or capacity factor (/. ) and lines of constant burnup... 

To illustrate use of Fig. 3.14, the example of the line L =0.9 will be discussed. Suppose that this 1060-MWe reactor is expected to operate at an availability-based capacity factor L = 0.9 with a 1-year interval between refuelings. The minimum fuel-cycle cost of 41 million will occur at a batch fraction /= 5 and a feed enrichment of 3.75 w/o U. This will require fuel to sustain an average burnup B of slightly over 40,000 MWd/MT. If average bumup should be limited for mechanical reasons to slightly over 30,000 MWd/MT, the minimum fuel cycle cost of 42 million will occur at / = 5 and a feed enrichment of 3.2 w/o, the combination suggested by the manufacturer for this reactor. 

Figure 3.15 shows the unit fuel-cycle cost in mills per kilowatt-hour as a function of the same variables. This unit cost is obtained by dividing the total cost in dollars by the electric energy in megawatt-hours. For example, the unit cost at L = 0.9 and /= 5 is 41,000,000/7317 X 10 MWh = 5.6 /MM or 5.6 mills/kWh. Because of the overlap of lines. 

To calculate fuel-cycle costs, it is necessary to focus attention on individual fuel sublots and determine ... 

A somewhat simplified, approximate procedure for calculating fuel-cycle costs will be illustrated by the example of sublot 2A of the PWR whose fuel management was described in... 

Table 3.6 gives numerical values for material quantities, unit costs or credits, and total direct costs or credits involved in each fuel-cycle step and calculates the overall net direct cost for lot 2A as 26.4 million. A total of 27.8 million is paid out for UF and fabrication in transactions 1 and 2 before any revenue is received from the sale of electricity. Because of this delay in receiving revenue, the total fuel-cycle cost includes also charges for carrying the 27.8 million advanced several years before it is recovered through revenue from the sale of electricity. Similarly, there is a financing charge on the net credit of 1.4 million in steps 3 throu 6, delayed until after revenue is received from the sale of electricity. 

The assumptions going into the calculation of direct costs in Table 3.6 will be described first. Then the procedure for calculating financing charges will be described, and finally a value will be given for the complete fuel-cycle cost. 

Table 3.6 Direct fuel-cycle costs or credits, lot 2A... 

Financing charges. A company generating electricity that pays out Z dollars for fuel-cycle costs f years before it receives revenue from generation of electricity from that fuel must pay to the bondholders and stockholders who advanced the funds for the fuel the return they require on their investment, and must also pay income taxes to the government on the profits from which the stockholders return is obtained. It is possible to represent all of these financing charges as the product yZt, where y is known as the atmual cost of money before income taxes. For a privately owned U.S. electric company, a value of / = 0.151 per year is representative. 

Between t2 and when payment is made for shipping fuel, the dollars invested in fuel is the difference between the initial outlay Zy + Zpg and the direct fuel-cycle cost Z, which is equivalent to... 

From the foregoing transaction times and the direct fuel-cycle costs or credits of Table 3.6, the carrying charges and total fuel-cycle costs may be calculated, as shown in Table 3.8 for sublot 2A. Division of the total fuel-cycle cost of 33,173,168 by the electricity generated by sublot 2A, 5.5456 X 10 kWhe, and conversion to mills per kilowatt-hour of electricity by Eq. 

Table 3.8 shows that more than 20 percent of the fuel-cycle cost arises from carrying charges. 

The procedure for calculating fuel-cycle costs and the assumptions regarding unit costs described in Sec. 5.1, and the assumptions regarding the time displacement between financial... 

Table 3.8 Calculation of fuel-cycle costs for sublot 2A from schedule of payments and receipts...

Figure 3.27 Components of steady-state unit fuel-cycle cost, PWR, three-zone fueling, 90 percent avail-ability-based capacity factor, 0.125-year refueling downtime.

The minimum fuel-cycle cost of around 5.9 mills/kWhe results from use of feed containing around 3.3 w/o which permits burnup of around 33,000 MWd/MT and an elapsed time of around 3 years between start and end of irradiation. 

Evaluate the fuel-cycle cost in mills per kilowatt-hour of electricity for lot IB of fuel charged to the 1060-MWe PWR power plant described in Sec. 4, using the material quantities, burnup increments, unit costs, and transaction times given in that section. The unit costs of uranium charged and recovered are as follows ... 

Very high bumup (192 GWd/t) has been achieved for mixed oxide fuel compared to the initial target value of about 62 GWd/t [3] and there has been very few fuel pin failures. This gives scope for significant decrease in fuel cycle cost. The smaller number of fuel pin failures has led to very clean sodium circuits which has also contributed to low radiological impact. 

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