The dose rate seems to be very high for DU gamma radiation. I calculated 400nSv/h using 0.7 Sv/Gy on contact for 0.2 w/o U235 for newly depleted material. The dose rate will increase a bit as daughter products accumulate over thousands of years, but that isn’t particularly relevant.

Steam is clear and colorless and is water vapor…water in gaseous form. Water vapor that condenses from its gaseous phase to its water phase is called condensed water vapor, or fluffy white clouds. Condensed water vapor consists of a multitude of tiny droplets of liquid water. Condensed water vapor converts to steam, invisible gaseous water vapor, if it is heated above 100 C.

The steam that enters a turbine at a nuclear plant is around 800 degrees F, depending on whether it is a pressurized or boiling water reactor. The white fluffy clouds of water droplets coming from the cooling towers at some nuclear plants is within several degrees of atmospheric temperature.

Exactly! Sound does travel through the vacuum of space, just not at a high enough frequency for human hearing to perceive. The frequency is very low; so low that it might be hard to describe it as sound at all. And sound travels very slowly in space, slower than a typical walking pace.