Estimate the doseequivalent rate at a distance of 80 cm from

Estimate the dose-equivalent rate at a distance of 80 cm from a 210Po–B point source that emits 2.2×107 neutrons s–1 and is shielded by 30 cm of water.
(b) How thick would the water shield have to be to reduce the dose-equivalent rate to 0.025 mSv h–1?

Solution

estimation Neutron dose equivalent rate by two methods:

1. Using the Source Activity and a Neutron Dose Constant

H=AN/d^2

A -source activity or mass

N-dose rate constant

d is the distance from the source to the point at which the dose equivalent rate is calculated

.2. Using the Neutron Fluence Rate:

Q=S/4pid^2 pi=22/7

N is the neutron fluence rate (n/cm 2/s)

S is the neutron emission rate (n/s)

d is the distance from the source at which the fluence rate is calculated (cm).