Source, Califomium-252 neutron

In the startup of a reactor, it is necessary to have a source of neutrons other than those from fission. Otherwise, it might be possible for the critical condition to be reached without any visual or audible signal. Two types of sources are used to supply neutrons. The first, appHcable when fuel is fresh, is califomium-252 [13981-174-Jwhich undergoes fission spontaneously, emitting on average three neutrons, and has a half-life of 2.6 yr. The second, which is effective during operation, is a capsule of antimony and beryUium. Antimony-123 [14119-16-5] is continually made radioactive by neutron... 

Among other isotopes produced at SRP were uranium-233 for breeder research, cobalt-60 [10198-40-0] for irradiators, plutonium-238 for spacecraft such as V ojager 2in.d lunar research power suppHes, and califomium-252 as a fast neutron source. The accomplishments of Du Pont at SRP are well chronicled (53). 

Gahfornium s uses are limited, which is why the U.S. Nuclear Regulatory Gommission, which controls the output and use of radioisotopes, has made califomium-252 available for commercial use at the cost of only 10 per millionth of a gram. This small quantity is adequate for many sources of free neutrons to be used commercially. For example, free neutrons can... 

Califomium-252 is an intense neutron source. One gram emits 2.4 x 1012 neutrons per second. This isotope shows promise for applications in neutron activation analysis, neutron radiography, and as a portable source for field use in mineral prospecting and oil well logging. 

J. T. MIHALCZO, The Use of Califomium-252 u a Randomly Pulsed Neutron Source for Prompt-Neutron Decay Measurements, Y DR 41 UCC-ND, Oak Ridge Y-12 Plant (1970) also. NucL ScL Eng., 53,393 (1974). 

The PINS equipment consists of a califomium-252 neutron source, a high-purify germanium (HPGe) gamma-ray detector, a portable multicharmel analyzer (MCA), a notebook computer, a detector stand and shielding, and certain support equipment. The equipment is contained for shipment and storage in six equipment boxes. 

---