23. 



no other safe disposal method was known. In time, under an accel- 

 erated program, storage space was exhausted so another set of tanks 

 was installed. Included in initial wastes was a considerable amount 

 of material for which there was use and which required recovery. 

 The stand-by plant was re -equipped and placed into operation and the 

 waste from most of the tanks was processed. In the chemical proc- 

 essing for recovery the waste fed to the recovery plant was added to, 

 resulting in more waste to store. 



The handling of radioactive wastes at Hanford involved stored 

 quantities measured in many millions of gallons, in underground 

 tank farms separated from two to six miles, and extensive transfer 

 pipe shielding. In initial plant operation, there were several types 

 of waste to handle: a) a high level waste from which a valuable con- 

 stituent was recovered by reprocessing; b) an intermediate waste, 

 active enough to necessitate storing; and c) a low level waste which, 

 after being passed through a series of tanks arranged in a "cascade" 

 system, could be fed into a cribbed excavation and allowed to seep 

 into the ground; by this arrangement, most of the radioactivity of the 

 low level waste is concentrated in sediments that fall out in the tanks. 

 The radioactive material appears to adhere to certain types of solids . 

 If the initial solution is of relatively low activity it can be disposed of 

 through cribs in the ground. A plant producing this type of waste is 

 still operating and the waste is being handled essentially in this fash- 

 ion. The high-level waste is being reprocessed after storage in tanks 

 for a period of a year and a half to two years. After recovery, nickel 

 ferrocyanide is used as a scavenging agent on the resultant wastes to 

 remove two major fission products, cesium 137 and strontium 90. 

 The nickel ferrocyanide is added to the waste before it leaves the 

 plant. The nickel ferrocyanide forms a precipitate, and the presence 

 of the phosphate ion aids in soil retention for cribbing the supernatant. 

 The low level supernatant is allowed to seep into the ground but tanks 

 are required to hold the sludges. The intermediate -type waste has 

 been concentrated in the past by evaporation but the ferrocyanide 

 treatment has proved effective and is now being used in lieu of evapo- 

 ration . 



DR. DAVID T. GRIGGS: Was the reason for the evaporation 

 because the sludge settled and put the water on top? 



DR. CHRISTY: The evaporator was actually a concentrator. 

 All the evaporator -would do is evaporate, the "overheads" were crib- 

 bed and the "hottoms" were transferred to storage tanks. The same 



