I don&#x27;t believe him.<p>1kg of uranium spread into 10x ingots, suspended in a pool of heavy water ... I don&#x27;t think this is sufficient to actually maintain criticality, even if he had a startup neutron source.  There isn&#x27;t nearly enough mass.  A commonly cited figure for a CANDU reactor is ~8 kg, in a well-designed geometry, with a properly designed reflector in addition to the moderator.<p>He used metallic uranium instead of uranium oxide.  Therefore, I don&#x27;t think he had a sufficient neutron source to get the chain reaction started.  For example, modern power reactors rely on (alpha + oxygen -&gt; neon + neutron) reaction, with the alpha decay of the fuel as the alpha source.<p>&quot;Should the reactor run away&quot;  Water-moderated reactors have a negative temperature coefficient of reactivity.  So if he actually achieved criticality and generated enough power to produce heat, the reactor would be self-regulating.