What will the radiation dose rate be for a 100 Ci Ir-192 source 25 feet from the source using a tungsten collimator with a HVL of 4?

To determine the radiation dose rate from a 100 Ci Ir-192 source located 25 feet away and using a tungsten collimator with a half-value layer (HVL) of 4, it’s essential to apply the principles of radiation attenuation and inverse square law.

Ir-192 emits gamma radiation, and its dose rate can be calculated using the known dose rate for a particular activity at a specific distance. Generally, for Ir-192, the standard dose rate is approximately 3 R/hr at 1 meter for a 1 Ci source. However, since the distance is 25 feet (about 7.6 meters), the inverse square law states that the radiation intensity decreases with the square of the distance from the source.

First, convert the source activity from Ci to R/hr:

1. For a 100 Ci source at 1 meter, the dose rate would be approximately:

Dose Rate = 3 R/hr * 100 Ci = 300 R/hr at 1 meter.

2. Next, apply the inverse square law to find the dose rate at 7.6 meters:

Dose Rate at 7.6 m = Initial Dose Rate / (Distance^2)

= 300 R/hr /