Dose rates seem off despite significant shielding - help validate

All,

I am trying to determine the shielding required to bring the dose rate on the surface of my reactor monolith down to acceptable dose rates (32 nSv/s, or 1 mSv/year). I am simulating a 5 MWth reactor design with tungsten carbide shielding. However, despite significant shielding (45 cm of tungsten carbide) I am still getting very high doses on the surface - 7.2 x 10^6 nSv per second.

I used the following examples as guidance:

I have attached my code below as well. In essence, I turned on photon transport, set up a current tally with the surface mesh of the outer shielding, set up an energy filter with the openmc.data.dose_coefficients, divided by the surface area, and normalized the data according to the procedure for k-eigenvalue simulations. Again, the full geometry and procedure is in the code, which I tried to comment and make as readable as possible.

I find it strange that even after 45 cm of tungsten carbide there is still significant dosage of photons - 7.2 x 10^6 nSv per second - this seems high to me. However, I may be wrong, so I was interested if someone could give me a sanity check on this. I want to make sure my code is structured properly.

parametric_keff.py (35.0 KB)
Thank you all in advance!

Hello asunkari!

The coefficients you’re using should be used to convert a fluence to a dose (hence a flux to a dose rate), not a current to a dose rate. Hope this helps.

Matteo

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