Fuel burnup costs

Fuel burnup costs. Using as fuel, the yearly burnup costs are... 

In many cases the additional fuel inventory charges and reactor vessel costs corresponding to higher conversion ratios more than offset the reduction in fuel burnup costs. The economically optimum reactor is neither a burner nor a converter with maximum conversion ratio, but somewhat betw een these extremes. 

Chem. proc. cycle, da3 S M23 T) M T) M23 T) MUT) M 23 T) BR(T ) Fuel inventory- charges, /day Fuel burnup costs, /daj Chem. proc. costs, /day Total variable cost, /day... 

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. 

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 ... 

Figure 2 shows burnup distribution in the unloaded FAs. Analyzing fuel loadings of Ukrainian reactors it is possible to state, that the use of some FAs in 4 annual fuel cycles has allowed to increase unloaded FAs average burnup from 38-39 MWd/kgU up to 41,5 MWd/kgU. It leads to a reduction of the fuel cycle costs by 10%. 

The inherent differences in the neutronics, and the low fabrication cost of HWR fuel, mean that the optimal enrichment in HWRs is much lower than in PWRs between -0.9% and 1.2% in current HWRs, corresponding to burnups between -14 MW d/kg HE and -21 MW d/kg HE. This is in contrast with LWR fuel, where the much higher fuel fabrication cost drives the optimal enrichment to as high a level as can be achieved. This pushes LWR fuel technology toward life-limiting fuel performance limits. In the current designs of HWR, most of the benefits of SEU can be realized at an enrichment level near 0.9%. This represents a small incremental step technically in the evolution of HWR fuel cycles. 

This section presents an overview of the INEL concept. This concept is not completely defined because of the short duration of this project. Table 1 lists the design parameters that have been chosen. The ranges indicate the design flexibility for minimizing fuel fabrication costs within acceptable safety limits. The INEL selected a power level of 1,000 MW(t) to achieve an acceptable plutonium destruction rate with a low power density over a large, but reasonably sized core. Although the core has a low power density, the fuel is expected to remain in the reactor for several years to achieve high burnup. A few (three to six) reactors of this power level could bum most of the plutonium in a reasonable time frame (30-40 years). 

The fuel cost items which vary with thc.se two parameters are (1) bismuth iiiM iiiiiiy, (2) fuel inventory, (3) fuel burnup, (4) thorium amortization, thorium burnup, and ((>) chemical processing. Nuclear calculations spei ilietl the fuel concentrations for both core. and blanket and breeding ratios, These I alues were then used to determine the chemical processing l yclc for the blanket and the pertinent costs. 

Fuel costs. The fuel costs as presented in this report include (1) bismuth inventory, (2) fuel inventory, (.3) fuel burnup, (4) thorium... 

The total power of the second core was fixed by the overall layout of the ship Otto Hahn. A change in lattice pitch could only be made satisfactorily if the size of the fuel elements and consequently the proper position of the control rod drives were changed too. Since in the optimum the fuel cycle costs depend not very strongly on the lattice parameters, the basic pin lattice of the first core was also taken for the second core. The main properties, in which the second core is essentially representative for the design of large commercially attractive ship propulsion reactors, are the power density and the burnup, the use of zircalloy for cladding and spacers, and finally the use of finger absorbers in the control elements. 

Although this policy would involve many risks, it would, on the other hand, allow the industry to profit from the most recent technical developments that are oriented toward the reduction of the fuel cycle costs either by simplifying the core design or by increasing the conversion ratio, the thermal efficiency, the burnup, or any combination of these factors. 

MWd/MT, now obtainable from oxide fuel before physical damage necessitates fuel replacement, fabrication and reprocessing contribute 6.7/MWd or more to the cost of heat, or 0.9 miUs/kWh to the cost of electricity in a power plant that is 30 percent efficient. It is thus of considerable economic importance to strive for maximum burnup until limited either by physical damage or by offsetting economic factors such as the higher cost of the richer fuel needed for higher burnup. The economic optimum burnup will be discussed later in this chapter. 

Uniform burnup. Because of the high cost of fuel fabrication and reprocessing, it is also important to manage fuel so that every element at discharge has been irradiated to nearly the same burnup. If this is not done, some of the fuel would have generated much less heat than elements that had received the maximum permissible irradiation, and the unit cost of heat from these underirradiated elements would be undesirably high. 

The economics of switching from natural uranium to SEU depend on the cost of uranium, the cost of enrichment, and the burnup achieved by the SEU fuel. Use of slight enrichment is even more attractive if the enriched material is RU. 

To determine the cost per kWh, it is necessary to know how many kWh of energy the fuel assembly will generate before it is discharged. In the early days of Generation II PWR plants, the average burnup that a fuel assembly would experience was 33,000 MW per metric ton of heavy metal (uranium and produced plutonium). More recently, the assemblies have been run to burnups exceeding 60,000 MWD/MTHM. 

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