jlconlin
commented
3 years ago @HunterBelanger Welcome to NJOY! We are glad that you are interested in making changes/improvements to NJOY.
Please note, that NJOY2016 is not being actively developed. Instead, we are working on NJOY21. It would be better if you could write a module for NJOY21 instead of NJOY2016. We have already modernized our THERMR module for NJOY21 and are putting the finishing touches on it.
I think it would be best if we had a teleconference to talk about this before you spend a lot of time working on it. We want to encourage this kind of contribution/collaboration so that it is available to the broader community. Would be willing to have a teleconference before you get too far along?
HunterBelanger
Hello,
My name is Hunter, and I am new here to the NJOY2016 project. I am currently a PhD student at CEA Saclay, working on Monte Carlo transport methods. As part of my thesis, I plan on implementing a method which has previously been developed by Pavlou and Ji, to treat and sample thermal neutron scattering data for use with continuous temperatures. The details of this implementation are outlined in the two papers which I have referenced to at the end. While the method they developed worked quite well, and seems to be in very good agreement with the traditional treatment of S(a,b) tables, there is currently not publicly available code to process the ENDF data in the required manner, and produce the required coefficients to sample alpha and beta.
Because there is currently no code to do this, I have started writing one, in the form of a new module to NJOY. Essentially, this new module would be called instead of THERMR, to treat the thermal scattering data. The module would read the S(a,b,T) table from the ENDF files, and then calculate all of the coefficients as outlined in the cited papers. It would also read the data for the coherent/incoherent elastic scattering data if present. While these are not considered in the papers, both of these are already given in a manner which can be treated continuously with regards to temperature, so no extra processing (or very little at most) should be required for this data.
There are a few point to consider however. As there are no available codes to process this data in the required manner, there are also no transport codes which currently use this data, which also means that there is no accepted format to currently store this data. I planned on writing a new format, which saves the data in an ACE compatible manner, as reading it from an ACE (like) file would be best for my currently desired uses. That being said, I would like if this project to be available and of use to all in the community. If you think it could be possible that this project be added to NJOY, I would greatly appreciate your thoughts and ideas, on implementation and output format before I fall to far down the rabbit hole.
A. T. Pavlou and W. Ji, “On-the-fly sampling of temperature-dependent thermal neutron scattering data for Monte Carlo simulations,” Ann Nucl Energy, vol. 71, pp. 411–426, 2014, doi: 10.1016/j.anucene.2014.04.028.
A. T. Pavlou, W. Ji, and F. B. Brown, “Implementation and testing of the on-the-fly thermal scattering Monte Carlo sampling method for graphite and light water in MCNP6,” Ann Nucl Energy, vol. 91, pp. 111–126, 2016, doi: 10.1016/j.anucene.2016.01.006.