What is heavy water?

I probably would not want to drink it. It is used in the production of nuclear energy. It contains some special isotopes that regular water does not have.

Water which uses deuterium, "heavy hydrogen," as opposed to the normal hydrogen, "protium." Deuterium is an isotope of H with two protons. The symbol for heavy water is D[subscript 2]O, and in molecular weight is consequently much heavier than the regular wet stuff. In the 1930s deuterium water was difficult to make, and was the development path of the Germans' haphazard atomic bomb project which had the Allies so worried.

Just check the internet. You get

Heavy water is chemically the same as regular (light) water, but with the two hydrogen atoms (as in H2O) replaced with deuterium atoms (hence the symbol D2O). Deuterium is an isotope of hydrogen; it has one extra neutron. Thus the deutrium atom consists of one proton and one neutron in the atomic nucleus and one orbiting electron. It is the extra neutron that makes heavy water "heavy", about 10% heavier in fact.

Funny enough, the film is based on partial truth. According to a book I own, there was indeed a supply of heavy water that the French handed over to the last British ships leaving France as France fell in June 1940.

I know this is an old post, but I've only seen it today and I just wanted to provide some info. And please, I'm typing this off the top of my head and it's just my 'general' knowledge of heavy water and nuclear chain reactions.

When physicists of that day tried to set off a nuclear chain reaction by bombarding atoms with neutrons, they found the neutrons were simply bouncing off the targeted atoms like ping pong balls off a concrete floor. Soon thereafter, they came to the conclusion they needed to slow down the speed of the neutrons so the targeted atoms would actually accept the neutrons and then the atoms would explode on their own due to the extra neutrons they had assimilated - and thus affect the other atoms in the same way. A chain reaction. (This is all happening in nano-seconds, mind you).

The only way of that day they could slow down these neutrons was by passing them through heavy water. That's why the heavy water was so critical. Later developements proved they could slow down the neutrons an alternate and simpler way and didn't need the heavy water. (Thus ensues the controversy of whether the British-sponsored Norwegian underground had to actually sink the supply of that country's heavy water, that was in-transit to Germany, and kill all those innocent civilians in the process that were on the same ferry transporting it).

As to where the heavy water comes from - it's in the water you're drinking right now. It's everywhere. But it is in minute quantities, like needles in haystacks. So minute, it has no effect at all. And that's why they don't 'make' heavy water, they 'filter' it. They filter it out of the regular water. It's an exhausting process. (Or was at that time, anyways). I don't exactly know how they do it, but I believe it's through a form of electrolysis. It took thousands and thousands of gallons of regular water to filter out say...a quart of heavy water - or less.

And because it was (and is?) such an exhausting process to filter out this water, it took quite a facility to do it. You just couldn't go out to your back yard and set up a processing plant. The one main place in Europe at that time that was set up for this was a hydro-electric plant in Norway. (As far as I remember. If there were other places, I'm sure I'll get corrected). It was much cheaper and expedient to simply get the water from the Norwegians. The Germans had this particular hydro-electric plant under their control and confiscated all the heavy water this facility had filtered. They tried to transport it to Germany in one final shot, but the Norwegian underground foiled their plans by sinking the ferry transporting the barrels of heavy water. A good flick to see regarding this is The Heroes of Telemark. (Though I don't know how accurate all the details and scenes are, as this is basically an action flick starring Kirk Douglas and Richard Harris, but it's pretty close to the actual events).

PBS a few years ago had a documentary on the sunken ferry where they dived to the bottom of the Norwegian lake and retrieved one or two of these barrels and opened them to test the purity of the heavy water. If memory serves me, they got some good samples.

And as to whether heavy water is safe to drink. The water we drink now has minute amounts of heavy water. (Very minute!) Filtered concentrated heavy water though, is not safe to drink.

Again, this is just my general knowledge of heavy water and nuclear reactions and something I typed in here in case anyone was still interested (or confused) regarding heavy water.