Pulsed columns then purify the plutonium, removing the troublesome fission products that remain.
2.
Pulsed columns were chosen to avoid the risk of a criticality incident occurring within the plant.
3.
Pulsed columns ( designated HA / HS ) are used to initially separate the majority of the uranium and plutonium from the fission products by transferring them into the solvent phase, which comprises tri-butyl phosphate in odourless kerosene ( TBP / OK ).
4.
The transfer is done in the HA column with the HS column providing further removal of fission products . 2 further pulsed columns ( designated BS / BX ) and a mixer / settler assembly ( 1BXX ) then separate the uranium and plutonium into separate streams.