So, they generally run on highly radioactive power sources, which are dangerous even during launch.

所以，飞船的飞行通常依赖于高强度的辐射能源，这种能源甚至在发射时也是有危险的。

youdao

Any missions hoping to go farther will need a means of acceleration that can get the spacecraft to the edge of explored space faster—before it has depleted its radioactive power source.

故而，任何更深空的宇宙探索都需要寻找技术途径来加速航天器，以便在放射性能源耗尽之前到达星系边缘。

youdao

Some elements such as uranium, commonly used as fuel in nuclear power plants, are always radioactive; there is no nonradioactive form of them that naturally occurs in nature.

一些如铀一般的元素，通常在核电厂用作核燃料，都是有放射性的；这些元素由于自身的性质是没有无放射性状态的。

youdao

In 2009, Esa funded a pilot project to examine the cost and practicality of establishing a European source of material for Radioactive Power Sources (RPS).

BBC: Nuclear space batteries could boost Sellafield jobs

Radioactive materials used in nuclear power generation must be isolated from human or environmental contact for thousands of years.

FORBES: The Economic Reasons Behind Nuclear Power

Rokkasho has been seen as a facility that will allow Tokyo to reduce radioactive wastes from its nuclear power plants by reprocessing spent nuclear fuel.

WSJ: U.S. Opposes Japan's Nuclear Plan