Page 259 - Handbook of Energy Engineering Calculations

1. Compute the heat produced by 1 lb (0.45 kg) of fissionable material
When all the nuclei in the atoms of 1 lb (0.45 kg) of fissionable U 235
fission, about 0.001 lb (0.45 g) of material converts to heat energy. Since by
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Einstein’s mass-energy equation, 1 lbm = 11.3 ×10 kWh of energy, 1 lb
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(0.45 kg) of fissioning U 235 produces 0.001 (3413)(11.3 ×10 ) = 39.5 ×10 9
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Btu/lb (91.9 ×10 kJ/kg). In this relation, the constant 3413 (3600.9) converts
kW to Btu (kJ).

2. Compute the heat equivalent of the fissionable material
Use the relation equivalent tons of coal per pound of U 235 = heat released
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per pound of U 235, Btu/heat released by 1 ton of coal, Btu = 39.5 ×10 /(24
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×10 ) = 1645 tons of coal per pound of U 235 (3290.0 t of coal per 1 kg U
235). Thus, it takes 1645 tons of coal to equal the potential heat produced by
1 lb (3290 t/kg) of U 235 in a nuclear reactor.

3. Compute the monetary worth of the nuclear material
Since heat is worth 40 cents per million Btu in this plant, the value of 1 lb
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(0.45 kg) of U 235 is (39.5 ×10 )(0.4/10 ) = $15,800, or about $34.80 per
gram of U 235.

Related Calculations. Use this general procedure for other fissionable

materials used for fuels in nuclear plants. The method presented is the work
of Henry C. Schwenk and Robert H. Shannon, as reported in Power
magazine.

With nuclear-power generation there is always the consideration of what to
do with spent fuel. Spent nuclear fuel is still radioactive and hazardous to
humans.
Spent nuclear fuel is a waste material that requires much more care than
ash from coal or SO emitted by a power-plant stack for a coal-fired
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generating plant. Environmental regulations are equally strong in their control
of nuclear waste, stack and boiler-grate effluent, and internal-combustion

engine exhausts.
But fossil-fuel-fired generating plants have an option nuclear plants do not
have. A fossil-fuel plant can purchase allowances to emit SO , as sanctioned
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by Title IV, the acid-rain provisions, of the 1990 Clean Air Act Amendments