A spare pressure vessel flange bolt is discovered inside the reactor shroud during a refueling outage of a nuclear power plant. The bolt has a mass of 250 grams and has the following elemental composition (by weight): Fe-80%, Ni-19%, Mn-0.5%, Cr-0.5%. The bolt was exposed to a mean thermal neutron flux of 2x10^12 n/cm^2s during the 3 years that it was in the reactor. Assuming that the bolt will be allowed to cool until 21 days into the outage, find the following;
a)The primary radioisotopes and activities of each in the bolt.
b)The approximate dose rate at a distance of 1m from the unshielded bolt
c)The amount of water necessary between the bolt and a technician to reduce this dose rate to 25 mrem/hr.