25. 



self-concentrate currently the Hanford wastes. Heat, however, 

 builds up in the accumulated sludges of these huge tanks and there is 

 periodic burping. This burping creates pressurized conditions which 

 must be taken into account in future tank construction. Burping is 

 being controlled by agitation. There is an agitation system in the de- 

 velopment stage, which, combined with stronger vessels, shows prom- 

 ise of being able to control the burping. 



I might point out that waste storage tanks are all underground, 

 and that they are concrete tanks, mild steel lined and capped. 



Another new process has been developed and a new plant built 

 which permits recovery of the desired elements without secondary 

 processing; this greatly reduces the quantity of wastes produced. 

 This improvement makes it possible to be optimistic about develop- 

 ing a self-concentration program. 



I want to emphasize this point: the new process gives better 

 recovery and lessens the quantity of waste but it does not eliminate 

 the disposal problem; the difficulties and expenses of storage are 

 still great. 



DR. J. W. WATKINS: Was it your statement that this waste 

 shouldn't be processed for around three years without the addition of 

 nickel ferrocyanide? 



DR. CHRISTY: We were discussing a process which is in use 

 today but is becoming obsolete. The waste from one particular proc- 

 ess has to be aged, mainly so that the recovery process will work. 

 This process was developed for an aged waste, and then it was found 

 that the nickel ferrocyanide could be used on this particular waste 

 after recovery. With these other (-unaged) wastes it appears that 

 self-concentration will be the answer. 



MR. WILLIAM B. HEROY: Your diagram shows a waste line 

 from one plant feeding into another plant; as one plant becomes obso- 

 lete does the other automatically become obsolete? 



DR. CHRISTY: After recovery is complete the subject plant 

 will be obsolete? 



MR. HEROY: In the series of tanks where the overflow from 

 one cascades into the next, what happens to the sludge of precipitated 



