Nuclear Reactor Health Physics and Radiation Protection Quiz

Introduction to Nuclear Reactor Health Physics and Radiation Protection

• Nuclear fission was discovered in 1938, and the first fission reactor operated in Chicago in 1942.
• At the end of 2011, there were 435 nuclear plants in operation, 61 under construction, 156 planned, and 343 proposed.
• Fission is the splitting of a nucleus into two approximately equal parts.
• Most fission neutrons are emitted almost instantaneously, while some are released seconds or even minutes after fission.
• Of the 2-4 neutrons produced per fission, some are captured in non-fission reactions, and some escape from the core (leakage); the remainder are available to cause further fissions.
• An assembly of fissile material is said to be critical if the number of neutrons from each fission equals the number of neutrons absorbed plus the number of neutrons escaping plus one.
• Majority of commercial power reactors are light water reactors (LWRs), which are of two types: pressurized water reactors (PWR) and boiling water reactors (BWR).
• The reactor core contains fuel assemblies or fuel elements, a control system, a moderator, a cooling system, and a biological shield.
• During shutdown, exposure control is more difficult because of the need to carry out non-routine jobs on radioactive systems.
• Sources of radiation in a reactor include fission neutrons and γ-rays, fission product decay γ-rays, neutron capture γ-rays, and decay γ-rays from activated materials.
• Fuel storage ponds pose two special hazards: criticality and loss of shielding.
• Fuel reprocessing is the chemical separation of spent fuel into uranium, plutonium, and waste streams. It presents severe radiological problems. Long-term storage can be done through wet storage in ponds or dry storage in casks with no significant radiological problems.