LYCOS RETRIEVER 
Nuclear Chain Reaction
built 654 days ago
"A nuclear reaction chain would immediately start in the Middle East and would potentially impact around the globe as other countries come to the conclusion that the restraint regime is over," argues Joe Cirincione, a US non-proliferation expert. "You could quickly see us go into a world with not eight or nine nuclear nations, which we have now, but ten, 20 or 25 - the nightmare world that John F Kennedy warned us about." The nightmare may be looming on the horizon but the problem remains trying to work out what to do about it. Fashioning a new consensus between the nuclear haves and have-nots looks far from easy.
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There were only 200 kilos -- not enough for a chain reaction, but enough to determine if a chain reaction was feasible. Experiments were begun, then abruptly interrupted when the Germans launched a lightning attack through Belgium into France one month later. The entire inventory of heavy water was taken to England. Two and a half years later it would be moved to a secret laboratory in Montréal.
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Taq polymerase, the key ingredient for a polymerase chain reaction, is extracted from a deep-sea, thermal vent-dwelling bacterium, Thermus aquaticus. It works well for copying, but not perfectly, making an error about once every 8 million base pairs. Before Taq polymerase, other polymerases were used, but many of them broke down at the necessary temperatures for the reaction to commence. The heating cycle is complicated, but includes temperatures briefly ranging almost all the way to the boiling point, so durability in the polymerase is essential.
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[S]ince the first man-made sustained nuclear chain reaction in 1942, nuclear technology has grown to tremendous proportions to meet the needs of a growing society. Starting out with the prime thrust of nuclear power, nuclear technology has rapidly expanded to fulfill a spectrum of needs in industry, the medical profession, and the research community. The nuclear engineering program at the University of Cincinnati (UC) has followed a similar path. Since its founding in 1957, the program has grown and developed to fill the needs of society for energy, health, and related support-system engineering. It is now an internationally-recognized training ground of quality nuclear engineers, health physicists, and medical physicists.
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The next step in the polymerase chain reaction is called annealing. The primers, which are custom-made, short DNA strands, are designed specifically to bond to sites at the beginning and end of the segment to be copied. If the primers are incorrectly designed or the temperature at this stage is wrong, the primer will bind randomly to the DNA, resulting in the wrong segment copy. Most primers melt at about two-thirds of the way to boiling point, and annealing, a 1-2 minute process, takes place at a few degrees below this.
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A fizzle occurs if the nuclear chain reaction is not sustained long enough to cause an explosion. This can happen if, for example, the yield of the fissile material used is too low, the compression explosives around fissile material misfire or the neutron initiator fails.
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Nuclear Chain Reaction