b'P ROVING THE P RINCIPLEfuel and to study reactivity changes in before we had high-speed computers The spent MTR fuel went to thehafnium, zirconium, and other fuel and elaborate computational modeling Gamma building in 26,000-pound carri-materials as a function of their total that now replace such experimental ers shielded with lead, steel, concrete,irradiation. One of its first operators, programs. and water. In the Gamma canal, six feet14Joe W. Henscheid, recalled: 13 wide and about sixteen feet deep, theThe spent fuel cooling off in the MTR fuel rested near the bottom. OperatorsWed irradiate a small piece of uraniumcanal opened up other research oppor- placed the elements, now referred to asfuel for several days in the MTR, then tunities. The fuel emitted gamma gamma sources, into cadmium boxestake it out and quickly insert it in the raysthe fresher the fuel the stronger and parked them at safe distances fromRMF. Some of the fission products in the radiation. They had a penetrating each other. Experimenters then dippedthe hot fuel sample, although relativelypower similar to X-rays and could, their samples into the canal at a pre-short lived, would decay into very high-among other things, kill pathogens. selected distance from the fuel element.cross-section neutron absorbers (so- Many industries in America wanted to Depending on how long the sample wascalled neutron poisons). Reactor know if gamma radiation could do to be exposed, its package could be adesigners, especially in the Navy something beneficial for their products. plastic bag, a can, or a special containernuclear program, were interested in The U.S. Army hoped irradiation would with a corrosion-resistant coating. Anknowing more about the adverse effectimprove the safety and shelf life of experimenter could specify the degreethese neutrons could have in power food. Phillips built a special Gamma of aging or freshness in the fuelreactors. In the RMF, as these poisonsFacility and opened it in 1955. The needed for a given test.built up, we had to withdraw control building was placed outside the MTRrods to keep the reactor critical. This exclusion area so that industrial scien- Sponsors paid non-profit rates (40 centsprovided a very precise way to track tists without security clearances, who per million roentgens plus shipping; $10and measure the effect of these poisons.were not allowed near the MTR, could minimum charge) and waited their turnRecall that this was all being done enter the building and do work. 15 on a first-come, first-served basis. Theysubjected nearly everything imaginableto gamma radiationmeat, grain, fruit,plastics, drugs, coal, gold, diamonds.Hawaii wanted to know if it couldimprove the shelf life of papayas andmangos and build its export trade.Restless visitors were always on thescene, anxious to learn how gamma rayshad changed their product. Typically,the canal contained forty to fifty fuelelements and scores of samples. 16Typical 1955 scene at the Gamma Facility. Sacks ofpotatoes await experimental irradiation in the canal.INEEL 55-16721 1 2'