Walkaway Safe. Thoron 500 fuel is in liquid form. If the reactor overheats for whatever reason, the Thorcon 500 will shut itself down, and passively handle the decay heat. No power, no machinery, no operator action is required. This is built into the reactor physics. The operators can do nothing to prevent safe shutdown and cooling. The ThorCon 500 has at least three barriers between the fuelsalt and the atmosphere. The reactor operates at garden hose pressure. In the event of a primary loop rupture, there is no dispersal energy and no phase change. The spilled fuel merely flows to a fuelsalt catcher where it is passively cooled. The most troublesome fission products, including Sr-90 and Cs-137, are chemically bound to the salt. They will end up in the drain tank as well. Visit Safety.