It has been recommended that storage of nuclear waste after sufficient pretreatement should be done in suitably shielded containers buried within rocks about

Options

A. 50 m deep
B. 100 m deep below ocean bed
C. 75 m deep
D. 500 m deep

Answer

### Step-by-Step Solution:

1. **Understanding Nuclear Waste**:
- Nuclear waste is a byproduct of nuclear reactions and can be highly radioactive. It poses significant health risks, including cancer and birth defects, if not managed properly.

2. **Importance of Shielding**:
- To mitigate the risks associated with radiation, nuclear waste must be stored in suitably shielded containers. This shielding is crucial to prevent radiation from escaping and affecting the environment and human health.

3. **Pretreatment of Nuclear Waste**:
- Before storage, nuclear waste undergoes sufficient pretreatment to reduce its radioactivity and volume, making it safer for long-term disposal.

4. **Recommended Storage Depth**:
- The recommended practice for storing nuclear waste is to bury it deep underground. The ideal depth for this storage is approximately 500 meters. This depth helps to ensure that the radiation does not reach the surface and that the waste is isolated from the biosphere.

5. **Evaluating Options**:
- When considering the options provided:
- 500 meters deep: This is the correct answer based on the recommendations.
- 100 meters deep: Incorrect, as it does not provide sufficient isolation.
- 75 meters deep: Incorrect for the same reason as above.
- 50 meters deep: Also incorrect, as it is not deep enough to ensure safety.

6. **Conclusion**:
- Based on the evaluation, the correct answer to the question is that nuclear waste should be stored in suitably shielded containers buried **500 meters deep** within rocks.