Neutron Sources For University Reactor Arrive

Press, Volume C, Issue 29651, 23 October 1961, Page 10

Neutron Sources For University Reactor Arrive

An innocent-looking 30gallon drum, crated and lashed to the foremast of the Port Fairy, which arrived at Lyttelton on Saturday morning has been watched with considerable respect throughout its journey from the United States, and will be handled with the scientific equivalent of kid gloves until it is delivered to the University of Canterbury this week. It contains the plutoniumberyllium neutron sources for the university’s sub-critical nuclear reactor, which will be commissioned in about two weeks. The “plutonium” label in the manifest is understood to have caused a stir among the crew when the unusual cargo came on board, but the shipping authorities were able to give assurance that, properly handled, it was quite safe. In fact this is the most powerful neutron source ever to be delivered to New Zealand, and it is believed to be the first that is plutoniumbased. Paraffin Wax Within the drum, ■which is almost full of paraffin wax—the simplest and most effective screen—is a shielded cylinder containing the three sources, two of two Curies each and one of one Curie. Each is about Ijin long and lin in diameter. The neutron sources and the experimental nuclear reactor, in which they will be used in the electrical engineering department of the School of Engineering, are gifts of the United States Government to New Zealand under its “atoms for peace” programme. At each port of-call in the United States, on the way across the Pacific, and down the east coast of New Zealand. the Port Fairy has been

visited by the United States Coast Guard or other similar authorities and by health officers to check that the special cargo is intact. This cargo is consigned to the Department of Scientific and Industrial Research, as Government agent, and during its unloading and trucking to Christchurch it will be supervised by an officer of the Dominion X-ray and Radium Laboratory. Probably tomorrow, it will be placed ire the charge of Professor N. M. MacElwee at the School of Engineering. “Neutron Howitzer” There the neutron sources will be transferred later into their permanent safe storage, called a “neutron howitzer” because, in addition to serving as a safe, it can be used to fire beams of neutrons for certain experiments.

In two or three weeks, the sources will be inserted for the first time into the nuclear reactor, which is already assembled. In handling, screw threads in the toip of the neutron source tubes will be engaged and they will then be lifted by 6ft tongs. Workers will not wear protective clothing, as the operation is safe if done quickly. However, constant checks will be made on the radiation. to which they are exposed. Professor MacElwee said last evening that the term "sub-critical nuclear reactor” meant that the neutrons could not multiply of their own volition to dangerous levels. However, when the neutrons bombarded the uranium fuel of the reactor there would be a controlled build up, but not to critical values. Therein lay the great experimental value of the whole installation. It could, in fact, simulate most of the reactions of a power reactor.