The 60Co source at a rate of 1.5 m/s, at a distance of 2 m you stopped to look into the 60Co (20 Ci) source for 20 seconds realizing that the interlock system is not operating and that the source is not in its shield, and you run out of the laboratory at a rate of 5 m/s.

1) Calculate your total absorbed dose from vising your friend’s laboratory and report your answer in SI units.

2) Calculate the absorbed dose rate to the cortical bone, skeletal muscle tissue, adipose tissue, lung tissue and water from this incident. 

3) Calculate your effective dose from this exposure to 60Co.

4) Based on actual measurements two days later, you determine that the source was 18.5 Ci. If the source was retracted in the shielding made of 10 cm lead and you passed 2 meters in front of the shielded 60Co source and you estimate your exposure time was 20 seconds, as described in the incident, calculate the change in your equivalent dose compared to the incident scenario. 

ADDITIONAL INFO:

 60Co decays with the emission of 1.17 and 1.33 MeV gamma-rays, each of 100% abundance. And that 131I emits both gamma and beta radiation and that the average energy of each 131I beta particle is:

Energy (MeV/transition) | Yield, f

0.0701 0.016

0.0955 0.069

0.1428 0.005

0.1917 0.904

0.2856 0.006