Calculating the integrated Beta dose in dense materials (radiolysis)

[solpete]

TL;DR Summary

I need to calculate the Beta dose deposited in plastic. Source is Co-60 or Cs-137. The question is relevant for radiolysis/degradation of plastic materials in a repository.

I have plastic which contains large amounts of Co-60 and Cs-137. I have already calculated the integrated (50k years) deposited dose from the gamma radiation using Monte-Carlo methods (SCALE).

I am now interested in the contribution to deposited dose from the Beta emissions.
-I am assuming that all Beta is stopped in the plastic itself.
-For Co-60, the average Beta energy is about E=0,31*(1/3) Mev.
-The conversion factor from MeV to Joules is C=1.6e-13 J/MeV.

Would the instant contribution to deposited dose in Gy (J/kg) per second from Co-60 Beta be:
E*C*I/m,

where I is the intensity in Bq and m is the mass?

Side note: Bremsstrahlung photons will also contribute to dose, but I have a feeling that this contribution is minor.

Peter, Phd

 

[Astronuc]

One would calculate the energy emitted from the ⁶⁰Co and ¹³⁷Cs. In one's problem, one wishes to calculate the dose in the plastic, so one must determine the mass of the radionuclides and then multiply by the ratio of mass of radionuclide(s) to the mass of the plastic.

 

[raining Pete]

Hello Peter, Phd,

Thank you for sharing your calculations and assumptions regarding the contribution of Beta emissions to the deposited dose from Co-60 and Cs-137 in plastic.

Based on your formula, the instant contribution to deposited dose in Gy (J/kg) per second from Co-60 Beta would be E*C*I/m. This formula takes into account the energy of the Beta emissions (E), the conversion factor from MeV to Joules (C), the intensity in Becquerels (I), and the mass (m) of the plastic.

I agree with your side note that Bremsstrahlung photons may also contribute to the dose, but it is likely a minor contribution compared to the Beta emissions.

Thank you for your contribution to the discussion on this topic.