1. The problem statement, all variables and given/known data A control rod to limit the rate at which a nuclear reactor is working is made from boron which is sealed in a casing. A boron atom (105B) is able to capture a neutron; an atom of lithium (Li) and an alpha particle being produced in the process. As a result helium gas is produced which occupies the spaces between the atoms in the rods which may be assumed to have a crystalline structure. Each cubic metre of the control rod can absorb 1.5 * 1027 neutrons before it must be replaced. (a) Write down an equation for the nuclear reaction which takes place in the control rods. (b) How many moles of helium are liberated in each cubic metre of control rod? (c) The boron atoms themselves occupy 75 % of the total volume occupied by the rods. Calculate the pressure inside the casing, at a temperature of 300 K, just before the rod is replaced. (Molar gas constant R = 8.3 J mol-1 K-1, Avogadro constant NA = 6.0 * 1023 mol-1.) Answers: (b) 2.5 * 103 mol, (c) 2.5 * 107 Pa. 2. The attempt at a solution (a) 105B + 10n → 63Li + 42α + 42He. Is it correct? (b) No idea where to begin.