Page 258 - Handbook of Energy Engineering Calculations

8. Compute the average fuel-cycle time
Use the relation A = B /F , where A = average fuel-cycle time, s. Thus A =
f
r
f
ma
f
19
26
7
2.18 ×10 /(1.5 ×10 ) = 1.45 ×10 s = 4040 h = 30 weeks, approximately.
9. Compute the reactor neutron flux
Use the reaction N = P C/Σf V , where N = reactor neutron flux; Σf = N U 235
f
T
f
f
× σ f 235 , where σ f 235 = total microscopic absorption cross section for U 235;
6
24
10
other symbols as before. So N = 500 × 10 (3 × 10 )/(0.00033 × 10 )(549 ×
f
6
13
10 −24 )(2.31 × 10 ) = 3.57 ×10 . Note that values of σ f 235 are obtained from
nuclear data sources.
Related Calculations. Use this general method for any reactor designed to
generate power. The method presented is the work of Henry C. Schwenk and
Robert H. Shannon, as reported in Power magazine.

At the time of this writing (1994), the United States is generating more
than 22 percent of its power requirements in nuclear plants. Thus, nuclear
stations are number two in generating electricity for the United States.
Nuclear power does not pollute the air. Recent studies show that the

nuclear plants currently operating annually reduce the amount of carbon
dioxide that would be emitted to the atmosphere by some 500 million tons.
Likewise, these plants reduce atmospheric pollution by 3.6 million tons of
methane and some 2 million tons of nitrous oxides annually. The NO

reduction closely approximates the requirements of amendments to the 1990
Clean Air Act. *

COMPARISON OF COAL AND FISSIONABLE MATERIALS
AS HEAT-GENERATION SOURCES

How many tons of coal are required to produce the heat equivalent of 1 lb

(0.45 kg) of fissionable U 235? If heat is worth 40 cents per million Btu (37.9
6
cents per 10 kJ), what is 1 g of fissionable U 235 worth? One ton of coal
6
6
contains 24 ×10 Btu (25.3 ×10 kJ).

Calculation Procedure: