Calculate the dose rate in a drum of U3O8

[Supaylek]

Summary:: Calcul of dose rate.

Hello everyone !
I have to calculate the total dose that an operator takes during different tasks in a workshop. .
I must not use numerical software, so it's only calculous with the data I have. My question could be considered as stupid but the engineer in charge of the radioprotection is not here and I don't find the solution on the internet.

Let's suppose we have had calculated the dose rate at one meter of a drum fulled of U3O8 (capacity of 213 liters) and the result is 2 µSv/h. Is it possible to apply a linear relationship between the volume of U3O8 (or mass) and the dose rate ? What would be the dose rate if the capacity of drum is around 118 litres, or if the drum is almost empty with only 100 grams remaining ? We keep a distance of one meter. I don't have access to the activity of the Uranium but only the dose rate at one meter.

Best

[Mentor Note -- Thread moved from the technical forums to the Schoolwork forums]

 

[Alex A]

Is this an academic question or a real risk assessment?

Are these all the data points you have been given? You are quoting quantity in liters and grams, do you have the density?

A real drum of U3O8 would have self shielding, which makes the dose rate non linear with the mass.

 

[Supaylek]

Both academic question and real risk, it's a kind of project for my school.

Well, when I have the measurement 2 micro Sv/h at one meter, it already takes into account the shielding of the drum I guess. Forget about the mass, my question is more about the radioactive source. It's common that if we have more radioactive material, than the doser is higher. But is this linear ?

 

[Alex A]

Neglecting shielding, radiation dose would be proportional to the activity of the source. Twice the source, twice the dose rate. Though you don't need it, it's also related to distance by the inverse squared law. So at 10 meters away, you would expect 1/100th of the dose rate.

The measured activity of uranium oxide is going to depend on more complex things, like how long since it was refined. U235 and U238 are alpha emitters, so they are not what you are detecting outside the drum. If you are very interested in the subject you could read about Uranium 'daughters' and which of those are removed by chemical extraction.

Assuming dose rate is linear to amount may be just fine for a school project. If you want to read more into the subject you can.