Information Notice No. 82-21: Buildup of Enriched Uranium in Effluent Treatment Tanks

                                                            SSINS No.:  6835
                                                            IN 82-21 

                                UNITED STATES
                           WASHINGTON, D.C.  20555

                                June 30, 1982

                                   TREATMENT TANKS 


All uranium and plutonium fuel fabrication licensees. 


This notice provides information about the potential for the buildup of 
enriched uranium in large liquid waste tanks after the waste solutions have 
been released from criticality control.  For nuclear criticality control 
purposes, licensees must sample or monitor effluent streams containing 
uranium prior to release of such liquids from favorable geometry hold 
systems.  On two occasions significant quantities of uranium were detected 
in large, non-favorable geometry effluent treatment systems as a result of 
post-precipitation or other chemical/mechanical action.  This information 
should be brought to the attention of all personnel having operational and 
safety responsibilities for waste treatment systems. 

Description of Circumstances: 

In one event, uranium was to be removed from waste liquids by precipitation 
and centrifugation.  The centrifugate was pumped through a polishing filter 
and an inline monitor.  If the uranium concentration in the filtrate was low
enough, the liquid was directed to a large retention tank with a side 
discharge.  At the request of the NRC inspector, the tank was inspected and 
found to have a significant quantity of uranium sludge below the discharge 
line.  Corrective actions included relocating the discharge line, improving 
the recirculation system in the tank, and periodic inspections of the tank 
for uranium buildup. 

In a second event, waste solutions containing very low levels of uranium 
were mixed with a precipitating agent, pumped through a filter press and 
collected in a large effluent holding tank.  The holding tank had a side 
discharge line about two feet above the bottom of the tank.  Sludge 
containing a significant quantity of uranium was found in the bottom of the 
tank.  Corrective actions included relocation of the discharge line, a study 
of the precipitation process to assure completion precipitation, prior to 
filtration, and periodic inspections to detect uranium buildup. 

                                                            IN 82-21 
                                                            June 30, 1982 
                                                            Page 2 of 2 


These incidents are significant to nuclear criticality safety in that 
enriched uranium was accumulating beyond "criticality safety release 
points".  If your effluent waste treatment system includes large tanks or 
other such hold systems, procedures for detection and removal of significant 
accumulations of enriched uranium from these tanks or other hold or handling 
systems should be reviewed for adequacy. 

No written response to this information notice is required.  If you need 
additional information regarding this subject, you should contact the 
Regional Administrator of the appropriate regional office. 

                             L.I. Cobb, Director 
                             Division of Fuel Facilities, Materials 
                               and Safeguards 

Technical Contact:  D. Sly

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