An atomic power nuclear reactor can deliver `300 MW`. The energy released due to fission of each nucleus of uranium atom `U^238` is `170 MeV`. The number of uranium atoms fissioned per hour will be.

Options

A. `30 xx 10^25`
B. `4 xx 10^22`
C. `10 xx 10^20`
D. `5 xx 10^15`

Explanation

To solve the problem, we need to determine the number of uranium atoms fissioned per hour in a nuclear reactor that delivers 300 MW of power, given that each fission of a uranium-238 nucleus releases 170 MeV of energy.

### Step-by-Step Solution:

1. **Convert Power to Watts**:
The power of the reactor is given as 300 MW. We convert this to watts:
\[ P = 300 \text{ MW} = 300 \times 10^6 \text{ W} \]

2. **Convert Energy from MeV to Joules**:
The energy released per fission is given as 170 MeV. We need to convert this energy into joules. The conversion factor is:
\[ 1 \text{ MeV} = 1.6 \times 10^{-13} \text{ J} \]
Therefore, the energy released per fission is:
\[ E = 170 \text{ MeV} = 170 \times 1.6 \times 10^{-13} \text{ J} = 2.72 \times 10^{-11} \text{ J} \]

3. **Calculate the Number of Fissions per Second**:
Power is defined as energy per unit time. Thus, we can express the number of fissions per second (\( n/t \)) as:
\[ P = \frac{n \cdot E}{t} \]
Rearranging gives:
\[ n/t = \frac{P}{E} \]
Substituting the values we have:
\[ n/t = \frac{300 \times 10^6 \text{ W}}{2.72 \times 10^{-11} \text{ J}} \approx 1.102 \times 10^{19} \text{ fissions/second} \]

4. **Convert to Fissions per Hour**:
To find the number of fissions per hour, we multiply the fissions per second by the number of seconds in an hour (3600 seconds):
\[ n = n/t \times 3600 = 1.102 \times 10^{19} \text{ fissions/second} \times 3600 \text{ seconds} \approx 3.97 \times 10^{22} \text{ fissions/hour} \]

5. **Final Result**:
Rounding the result gives:
\[ n \approx 4 \times 10^{22} \text{ fissions/hour} \]

### Conclusion:
The number of uranium atoms fissioned per hour is approximately \( 4 \times 10^{22} \).