Saturday, December 13, 2008

More on ammonium dinitramide (ADN)

After it came out that NASA was investigating ammonium dinitramide (ADN) as a replacement for ammonium perchlorate (AP) in the Ares SRMs, I looked at Wikipedia for a little background on this stuff. I noted that it was more sensitive/hazardous than AP but that it was more efficient and lighter. Without any quantification of said hazard, my previous post ended with the thought that this could lead to small H's that fell under the 62.5g limit. Well, the Rocketry Planet thread on the NASA story led to a comment by Anthony Cessaroni of CTI. Since Anthony is what you call a professional rocket scientist/propellant guy, I thought his comment was worth noting. That is, it puts to bed any wild gleam-in-my-eye over 62.5g H's:
Anyone who knows anything about ammonium dinitramide (ADN) or has worked with it knows better. It’s a class 1.1D high explosive for starters and is thermally unstable. It’s also quite hygroscopic and although water does stabilize it somewhat, that makes a mess of propellant formulation chemistry and ballistics. Its intermediate decomposition products are ammonium nitrate and nitrous oxide. ADN is also photo sensitive. In other words it doesn’t care much for light.

ATK and the Navy have been playing around with it for years for tactical applications and had set up a pearling tower a while back to convert it. About 4 years ago, DREV was attempting to mix about 40 kilos of it with an alternative binder. I actually had the mixer involved at our facility for a program at one point. In any event, one of the blades touched the bowl and the batch detonated. The mixer was about 12 feet tall and weighed at least a couple of tons. The largest piece they found was about the size of a quarter and the damage to the blast proof facility was over $1 million dollars. The former Soviet Union flew some tactical systems with it but lost the plant where the ADN was made when it exploded. ADN has a lot of history.

There are better solutions for this especially since it’s not a tactical application.