I don't know exactly what risk modeling the PSC could have...

I don't know exactly what risk modeling the PSC could have specifically requested in response to the concerns raised. I had previously read the report presented to the AELB that contains RESRAD modeling results for LAMP residues so I don't know what their exact objections to the previous modeling results are. Like you said, it might just be that they want modeling done based on ACTUAL residues not predicted residue compositions, which would have to wait until some actual product is made from the kilns.

In the previous modeling report, it was assumed that disposed solid residues from LAMP would be covered with 1 meter of soil. That option was modelled and found to present a very trivial gamma exposure. If they want, they can model radon exposure from the buried solid waste, as I have examples of EPA studies where that was done. The outcome would probably be cancer risks from radon that are many orders of magnitude less than one cancer incidence per million persons exposed, since the soil cover will inhibit radon release rates and huge dilution factors would result from the mixing of slowly diffusing radon from soil into ambient air. Again, the gaseous radon emitted would be extremely diluted and in the form a radioisotope decay product of Th-232 which has a half life of 55 seconds so would only exist for a few seconds before decaying into a solid element.

As far as stack emissions containing Th-232 particulate dusts, I have read the LAMP has stack air filtration capture systems to control the emissions of dust. LAMP has designed their pollution control equipment to comply with emission standards. I do not have direct knowledge of what the expected particulate emission rate would be AFTER filtration, but it would certainly be quite small if the capture equipment is functioning properly. Furthermore, downstream dilution and disperson modeling could be used to also show that any exposures to partulate forms of Th-232 by off-site residents would be predicted to be many orders of magnitude less than a one in a million cancer risk. Therefore, there would seem to be no potential for anyone to have measurable alpha exposures other than certain on-site plant employees who would occasionally have to change the baghouse dust filters on the air pollution equipment or otherwise working directly around the kilns and other sources of dry dust residues. But that becomes a question of occupational exposure, not offsite resident exposure. Occupational exposures can be controlled and prevented by wearing appropriate personal protective equipment (PPE) such as respiratory protection masks, gloves, and Tyvex suits.