I have been running the depletion calculation example available on github with the goal of evaluating gaseous radionuclide buildup in fuel pellets (with burnup of 50 GWd/MTHM). I modified the example to use the ENDF/B-VII.1 Chain (PWR Spectrum) data. Interestingly, while some isotopes such as Kr-85 and I-129 are in good agreement with the DoE data, I am seeing very little H-3 buildup in the fuel material (roughly 10 orders of magnitude less per fuel mass than described in the benchmark).
The main source of tritium in spent fuel should be ternary fission reactions. I did not find any reference to this reaction in the depletion chain file. Does OpenMC (or available depletion chains) support the evaluation of H-3 in depletion calculations?
Thank you Shimwell for you attention! It appears that the post you mentioned focuses on (n,t) reactions, whereas I’m actually curious about ternary fission reactions. Upon further investigation, I managed to find this worksheet example by Paul Romano on plotting fission product yields from chain files. Using that example, I am not seeing any ternary fission products such as H-3 and He-4.
Are there any available nuclear data libraries that do support ternary fission reactions, that could potentially be used with OpenMC?
Nice find. Yes you are right the other post is on the (n,t) reaction and the quick fix for that was to add a line to the xml chain file. I suspect the quick solution for this issue would also be to add a line to the chain file to ensure this tritium production from n,f reactions is accounted for. Longer term I guess we need to work on the chain file processing scripts. So while it is a different reaction I suspect the solution is similar. I think this is a case of the processing of nuclear data libraries into chain files misses the T produced in ternary fission but I would have to dig into the source code to be sure