Hanford critical radiation dosimeter

The modified Hanford critical radiation dosimeter provides a rapid, accurate, and relatively inexpensive means of determining neutron and gamma radiation exposure dose from a radiation release of accident proportions. An accident is defined as a radiation release of such magnitude that personnel in the vicinity of the release may receive a total absorbed radiation dose in excess of the permissible limits. The neutron exposure estimation is arrived at rapidly by counting either the gold or TLD chips from the center of the paraffin moderator and performing the calculation. If the neutron spectrum has not been greatly degraded toward thermal energies, the dose value thus obtained will be accurate to within +-15%. Degradation depends on the amount and type of shielding material through which the neutrons pass before reaching the dosimeter. Shielding materials with a high hydrogen content, such as concrete, paraffin, and water, are usually used when neutron shielding is desired. Nonhydrogen-bearing shielding materials commonly used for beta and gamma radiation shielding, such as lead or iron, are relatively poor neutron shields