As usual, a good first move would by tidying up the input. Splitting the hydrogen and oxygen up and seperating out the uranium would be a good idea.
Note that if there's only one uranium atom in the tainted water, it's always on the lower part.
Using a sensor loop that checks if the lower atom of the water is uranium, strips it and rotates the molecule around should take off all the uranium. After that the remaining hydrogen and oxygen needs to be broken down and output elsewhere.
I find this does an adequate job of it
Note the red waldo is parking on Bond- and note that the output hydrogen / oxygen stream has hydrogens in two different places.
The uranium can go to the laser, probably though a reactor with an edge-triggered control mechanism so you can control the flow. The hydrogen and oxygen need to make hydrogen peroxide, but first they need to be sorted.
Check the solution to the level Split Before Bonding on Danopth.
Let's sort the hydrogen and oxygen and then double bond them before sending them on to a reactor which acts like the solution to Split Before Bonding.
This will do it. A pass across design will be a lot faster.
...like this.