During early research in nuclear energy, why were scientists surprised that the products from splitting a uranium nucleus had less mass than the reactants? They expected that the large release of energy would cause an increase in mass. Up to that time, only chemical changes were known to form less mass than they started with. All known changes always started and ended with the same amount of mass. Other known nuclear changes resulted in the same mass of products as reactants.

(a) Write the decay equation for the decay of 235U. (b) What energy is released in this decay? The mass of the daughter nuclide is 231.036298 u. (c) Assuming the residual nucleus is formed in its ground state, how much energy goes to the particle?

Enter the correct nuclide symbol in each open tan rectangle in Figure P43.25, which shows the sequences of decays in the natural radioactive series starting with the long-lived isotope uranium-235 and ending with the stable nucleus lead-207. Figure P43.25

The electrical power output of a large nuclear reactor facility is 900 MW. It has a 35.0% efficiency in converting nuclear power to electrical. (a) What is the thermal nuclear power output in megawatts? (b) How many 235U nuclei fission each second, assuming the average fission produces 200 MeV? (c) What mass of 235U is fissioned in one year of fullpower operation?

(a) Calculate the energy released in the neutroninduced fission reaction n+235U92Kr+142Ba+2n, given m(92Kr)=91.926269 and m(142Ba)=141.916361u. (b) Confirm that the total number at nucleons and total charge are conserved in this reaction.

(a) How much energy would be released if the proton did decay 1uria the conjectured reaction (b) Given that the decays to two (s and that the will find an electron to annihilate, what total energy is ultimately produced in proton decay? (c) Why is this energy greater than the proton's total mass (converted to energy)?

(a) How many 239Pu nuclei must fission to produce a 20.0kT yield, assuming 200 MeV per fission? (b) What is the mass of this much 239Pu?

Assume onefourth of the yield of a typical 320kT strategic bomb comes from fission reactions averaging 200 MeV and the remainder from fusion reactions averaging 20 MeV. (a) Calculate the number of fissions and the approximate mass of uranium and plutonium fissioned, taking the average atomic mass to be 238. (b) Find the number of fusions and calculate the approximate mass of fusion fuel, assuming an average total atomic mass of the two nuclei in each reaction to be 5. (c) Considering the masses found, does it seem reasonable that some missiles could carry 10 warheads? Discuss, noting that the nuclear fuel is only a part of the mass of a warhead.

Explain, in terms of conservation of momentum and energy, why collisions of neutrons with prawns will thermalize neutrons better than collisions with oxygen.

(a) Calculate the energy released in the neutron- Induced fission reaction n+235U92Kr+142Ba+2n , given m(92Kr) = 91.926269 u and m(142Ba)= 141.916361 u. (b) Confirm that the total number of nucleons and total charge are conserved in this reaction.