The problem with super-secret projects is that more effort is put into secrecy than is allocated to the rest of the project. I was a Lab Tech in the industry at the time of the SL1 incident in Idaho, Jan 3, 1961. I don't know about the geometry of the SL1 but our research reactor's fuel rods (actually plates) sat in a frame work of slots and the control rods were inserted between the plates. Only gravity held the fuel in place. For whatever reason, the control rods would sometimes stick to the fuel plates and they would be withdrawn together. Then the fuel element would slip free and drop into the core causing a power excursion. Detection of the power excursion would drop the control rods back into the core (they were held to the control mechanism with electromagnets) to scram (shut down) the reactor. The AEC mandated that the fuel elements needed to be secured in place rather than simply relying on gravity. Accomplishing that task on a hot core is another story. My real question was "why did it take a Federal Mandate to implement the safety device?" That was when I started looking into another career path... John Ferrell http://DixieNC.US ----- Original Message ----- From: "Russell McMahon" To: "PIC List" Sent: Wednesday, September 01, 2004 1:14 AM Subject: [OT:] Nuclear Accidents > I'll put this under a separate subject as it MAY have a life of its own. _______________________________________________ http://www.piclist.com View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist