[IROC]

I drive past this place twice a day...

Monday, Nov. 4, is the 70th anniversary of the morning the Graphite Reactor -- then known as the "Clinton Pile" -- achieved a nuclear chain reaction for the first time. It was the initial major milestone for the facility designated X-10 to demonstrate the production of plutonium in a nuclear reactor.

The reactor was constructed with remarkable speed -- work had started only the preceding February -- cloaked in the now legendary secrecy of the Manhattan Project. The project was led by Enrico Fermi, who directed the small staff (by Manhattan Project standards) with his mixture of English and Italian. The staff included future Lab Director Emeritus Alvin Weinberg.

Tim Gawne, who occasionally combs the records looking for institutional history related documents related to his work, recently came across some documents relating to "critical reached." According to Tim:

"The reactor suddenly at 5 a.m. came to life showing signs of a self-sustaining chain reaction. As the story goes one was dispatched to wake Fermi to come and verify that they had reached criticality.

"There are theories surrounding why it went critical early. One is that the person on duty wanted it to go critical when they were there. There may be a more simple explanation -- a miscalculation.

"Initially, it was calculated long before the pile was finished that it would take in excess of 70 tons of fuel to bring the reactor to criticality. This was actually calculated by Alvin Weinberg. However closer to the moment it was surmised that it would take 35 tons of material. It actually only took 30.5 tons. So if you assume the average of 2.5 tons per hour you come closer to a more timely arrival of criticality -- after at least a breakfast of biscuits and gravy with a side of orange juice of around 7:30-8 a.m."