Is my uranium math mathin', or am I tripping?

We have 1 Uranium fuel cell (UFC) with textbook energy potential of 8 GJ.

We send it to a reactor for 8 GJ. We get 1 Depleted UFC (DUFC).

Reprocessing formula: 5 DUFC = 3 U238.

With Legendary P3 modules in Centrifuge: 5 DUFC = 4.5 U238.

Our 1 DUFC gives 0.9 U238.

Kovarex: 40 U235 + 5 U238 = 41 U235 + 2 U238.

Simplified conversion: 3 U238 = 1 U235.

With productivity: 3 U238 = 1.5 U235.

Simplified: 1 U238 = 0.5 U235.

We will balance our 0.9 units of U238 we got from reprocessing via Kovarex to exactly fit UFC production formula ratio of 1 U235 per 19 U238.

A = new U238 value.

B = new U235 value.

D = change in U238.

A = 0.9 - D.

B = D x 0.5.

B = A / 19.

D x 0.5 = (0.9 - D) / 19.

0.5 D = ~0.047368 - ~0.052632 D.

~0.552632 D = ~0.047368.

D = ~0.085714 (this is how much U238 we convert).

A = ~0.814286 (this is how much U238 remains).

B = ~0.042857 (this is how much U235 we get).

A to B ratio is now that of UFC production.

1 U235 + 19 U238 (+ Iron plates, but irrelevant here) = 10 UFC.

With productivity: 1 U235 + 19 U238 = 20 UFC.

~0.042857 U235 + ~0.814286 U238 = 0.857143 UFC (this is basically now the DUFC to UFC conversion rate).

So technically we lost 1 - 0.857143 = 0.142857 UFC for 8 GJ, which translates to 1 UFC netting us exactly 56 GJ of energy. And that is without neighbor bonus of the reactor.

Is my math mathin'?