1.30 points, A nuclear power company has been working on a conceptual design for a differenttype nuclear reactor due to the availability of newly developed alloys that can stand much highertemperatures. The new concept is based on the plate type fuel elements that use U-235 and U-238.Each element is in the shape of a thin slab with 160 cm high, 12 cm wide and 0.6 cm thick(space between the claddings). On each side, a cladding with a thickness of 0.016 cm is added.The coolant bulk temperature, Tf, is fixed at 316 oC. The following are the properties of the fueland cladding. Density of fuel (U-235+U-238) = 19.5 g/cm3, thermal conductivity of fuel=32 W/mK, thermal conductivity of cladding=23 W/mK. Nuclear fission cross section=375x10-24 cm2 (375 barns). Thermal neutron flux=3x1013 Neutrons/cm2s. (a)If the maximum temperature of the fuel is allowed at 500 oC and the convective heat transfercoefficient between the cladding and the coolant is 2.6x104 W/m2K, what is the maximumfuel enrichment (weight percent of U-235) ? (b)For this case, if the fuel enrichment is decreased to 2% and everything else is the same asthose in case (a), what would be the percent decrease in Carnot efficiency as compared tothat of case (a) ? The Carnot efficiency for a nuclear power plant is defined as 1-TL/TH ,where TH is the temperature at which heat is added to the coolant, that is the cladding surfacetemperature. TL is the sink temperature at which heat is removed from the condenser. UseTL= 5 oC for your calculation.

1. 30 points, A nuclear power company has been working on a conceptual design for a different type nuclear reactor due to the availability of newly developed alloys that can stand much higher temperatures. The new concept is based on the plate type fuel elements that use U-235 and U238. Each element is in the shape of a thin slab with 160cm high, 12cm wide and 0.6cm thick (space between the claddings). On each side, a cladding with a thickness of 0.016cm is added. The coolant bulk temperature, Tf, is fixed at 316C. The following are the properties of the fuel and cladding. Density of fuel (U235+U238)=19.5g/cm3, thermal conductivity of fuel =32W/mK, thermal conductivity of cladding =23W/mK. Nuclear fission cross section =3751024cm2 ( 375 barns). Thermal neutron flux =31013 Neutrons /cm2s. (a) If the maximum temperature of the fuel is allowed at 500C and the convective heat transfer coefficient between the cladding and the coolant is 2.6104W/mK, what is the maximum fuel enrichment (weight percent of U235 )? (b) For this case, if the fuel enrichment is decreased to 2% and everything else is the same as those in case (a), what would be the percent decrease in Carnot efficiency as compared to that of case (a) ? The Carnot efficiency for a nuclear power plant is defined as 1TL/TH, where TH is the temperature at which heat is added to the coolant, that is the cladding surface temperature. T is the sink temperature at which heat is removed from the condenser. Use T=5 " for your calculation