A nuclear reactor using `.^(235)U` generates `250 MW` of electric power. The efficiency of the reactor (i.e., efficiency of conversion of thermal energy into electrical energy) is `25%`. What is the amount of `.^(235)U` used in the reactor per year? The thermal energy released per fission of `.^(235)U` is `200 MeV`.

Explanation

To solve the problem, we need to find the amount of Uranium-235 (U-235) used in a nuclear reactor that generates 250 MW of electric power with an efficiency of 25%. We will follow these steps:

### Step 1: Calculate the total thermal power produced by the reactor.
The efficiency of the reactor is given as 25%. This means that only 25% of the thermal energy produced is converted into electrical energy.

\[ \text{Thermal Power} = \frac{\text{Electrical Power}}{\text{Efficiency}} = \frac{250 \, \text{MW}}{0.25} = 1000 \, \text{MW} \]
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