Entranceway Radiation Calculator

Determining Radiation Doses and Entranceway Geometry

Radiation Calculator Measurements

Radiation Calculator Measurements

High radiation levels from a nuclear weapon can enter the shelter through the entranceway. It is the most misunderstood area of radiation shielding. Good entranceway design will not allow more than 5 rems to enter the shelter at Point Z. Heavy steel hatches are considered invisible to radiation unless the hatch and tunnel connecting to the hatch is 1.125 inches thick or one HVL (Half Value Layer). The larger the entranceway diameter tunnel, the more radiation is allowed to enter. Placing radiation shielding barriers in the entranceway is not efficient since it has to be so thick and heavy and creates a safety hazard. POP 13.01 does not allow blocks, bricks, or plates to be used. The farther the hatch is away from the connection to the shelter the less radiation enters are Point Z. Neutron radiation has a lifespan of not more than 60 seconds. Any shelter in the neutron radiation area will suffer ground shock which will alert the shelterists to walk away from Point Z. for 60 seconds until the neutron radiation phase passes. After this time gamma radiation is the main threat and will last 30 days. After 30 days 99% of the all the radiation produced will have fallen and decayed. (See Radiation Tables)