51. 



Clinch River, and be disposed of by dilution. There are several 

 types of wastes. The principal types are: sanitary sewage which is 

 treated separately; cooling water which has no opportunity for being 

 contaminated with radioactivity and can be discharged directly to 

 White Oak Creek; the slightly- contaminated process water from lab- 

 oratory sinks, and the like, which, after brief retention, is discharged 

 into White Oak Creek; chemical wastes; and metal wastes. Chemical 

 wastes, which we call intermediate, containing 1 /300th to l/30th of a 

 curie per gallon, have to be disposed of with care; and metal wastes 

 have to be stored in tanks until reprocessed for recovery of the fuel 

 materials . 



About 1951 the intermediate radiochemical wastes were filling 

 up the available concrete storage tanks, despite the use of the waste 

 evaporator, and the construction of new tanks had to be considered. 

 Prior to that a survey by a geologist had indicated that a nearby bed 

 of Conasauga shale had a thickness of at least 1500 feet. The shale 

 is relatively impervious and laboratory tests showed that it might be 

 suitable for containing wastes of this kind. We first excavated an ex- 

 perimental pit with a capacity of 200,000 gallons (Pit No. 1). After 

 introducing 130,000 gallons of evaporator concentrate a break-through 

 to the surface occurred because it was on a steep hillside. Subsequent 

 excavations have been located more carefully. Two additional pits 

 have been dug, and another is to be started in October 1955, each hav- 

 ing one million gallons capacity (Pit No. 2, No. 3, and No. 4). The 

 use of Pit 1 was discontinued after a few months. 



Pit 2 and Pit 3 are still in operation. Pit 3 is nearly full, Pit 2 

 is two-thirds full, and Pit 4 will be in operation in time to relieve these 

 when they are full. We are trying to evolve a safe but economical de- 

 sign to get the maximum possible efficiency from pits. Since June 

 1952, we have put two and a quarter million gallons of intermediate 

 level waste containing nearly 30,000 curies of activity into these pits. 

 About 75 per cent of the activity is due to ruthenium, and about 20 to 

 22 per cent is due to cesium. Three or four monitoring wells were in- 

 stalled around each pit for making radiologs and taking samples in an 

 effort to detect the underground movement of the waste. Sampling at 

 a distance of 80 to 85 feet showed, after about a month and a half, 

 ruthenium and nitrates in the well. In the highest concentration, the 

 activity was about 70,000 counts per minute per milliliter and the 

 nitrates about 3,000 parts per million. The activity of the waste as 

 originally put into the pit was about a million counts per minute per 

 milliliter, at 10 per cent counting efficiency, or about 10' disintegra- 

 tions per minute per milliliter. 



