1. There are also concerns about militants trying to obtain radioactive materials.

2. The scientists used other radioactive isotopes to date the samples they examined.

3. In fact, it is the biggest pulse of radioactive liquid dropped in the ocean ever, he said.

4. Robots and even humans could one day make nuclear power by using radioactive decay there.

5. The cost of completing the plant to treat radioactive waste now stands at $16.8 billion.