The 2nd design flaw is the positive void coefficient due to it using light water as a coolant and graphite as a moderator.  In its scheme, the light water is a neutron absorber, and if steam voids form in it, there&#x27;s less water absorbing neutrons.  More neutrons -&gt; more split atoms -&gt; more heat -&gt; more&#x2F;bigger voids, this repeats until the reactor sufficiently disassembles itself: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Void_coefficient" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Void_coefficient</a><p>Such designs are illegal in the US, one of the reasons all but the latest version of the CANDU reactor can&#x27;t be used here.