This chart shows the essential argument -- the proliferation risk of three spent-fuel strategies over time: 1) use once and send to storage (red); 2) conventional reprocessing (green); 3) Moltex process (blue). Note: each step that is shown in parentheses is relevant for only one fuel strategy. 6/9

Here's a schematic of shielding on the N.S. Savannah, with 84 cm. of water along with much thinner layers of lead, iron, and polyethylene. The "shielding" also included 2.7-5.2 meters of equipment space.
Source: www.nrc.gov/docs/ML1000/...

From a presentation by Robin Rickman of @terrestrialenergy.bsky.social, this chart explains how fluid-fuel reactors can be much less expensive than conventional nuclear reactors. I'll try to explain the meaning of each bar in the chart. 1/7