"Separately, these three types of risks are not great causes for concern."

(Paragraph 5)

The synonym of the underlined word is

danger

Discussion:

Finally, there is the problem of accidental expo-sure due to a leak or an explosion at the power station. As with the other two hazards, this is not very likely, so that it does not provide a serious objection to the nuclear program. Nevertheless, it can happen. Separately, these three types of risk are not great causes for concern. On the whole through, the probability of disaster is still high.