Plastics in the tunnel question?
 

Hello all. Its been a long, loooong time since I have posted on this forum. Sorry but work, school and falling in (and out) of love (twice) have kept me extremly busy the last couple of years. More then I can handle some days. :dead:

Anyway as we know on nuke boats there is a 'tunnel' seperating the reactor end of the boat from the 'front of the boat'. For sheilding and safety to the crew. This tunnel is heavely sheilded with lead, tungsten, H2O and diesal fuel etc. It is also sheilded with a plastic(?) or polymar(?) type of plastic or resin.

My question is what is the type of plastic or more importantly what is this "plastic" sheilding for? Alpha waves?

I am in school at present and my instructor used to do NDT work on British submarines in the 60's.

When I asked him this question he stood by his non disclousure agreement but I am sure I have either heard or read about it in detail some where in the past.

Can anyone help?

One day I WILL get back into SC/DW. Just need the time. :yep:

Several things come to mind immediately.

First is that "depleted" uranium is a very good neutron shield. Not even lead is as good as U-238. And the toxicity of uranium is far above arsenic, mercury, lead, iron, tungsten, and titanium. There is probably a fraction of a millimeter of uranium in that shielding. The plastic will serve to stop alpha particles from said uranium, but the lead would do the same. However, the uranium would be most efficient if it was furthest from the reactor, meaning that the lead would be closer. That plastic probably shields some steel, which is shields the uranium, which shields the reactor.

Second is that plastic will prevent galvanic corrosion and surface oxidation in that oxygen-enriched area. Zero maintenance is good maintenance on a boat. Anything you don't have to paint on a regular basis is, like, totally cool.

Third is that, if there really was a thermal event, that plastic would melt. Possibly sealing off the room. Yes, that plastic will breakdown and form vapors, but every last little bit of shielding and/or prevention is taken into account when a boat is designed. The engineers get paid to do their jobs, and given all considerations (both political and resource), boats are actually designed well. Things that sound stupid might very well be up until that one lucky break where they are a saving grace.

Hey tycho102: Thanks for the answer but...have since relearned that the shielding mentioned is for neutron radiation. Depleated uranium or tungsten or lead are crappy forms of shielding for this type of radiation. Heres a link than can explain it better then I: http://en.wikipedia.org/wiki/Neutron_radiation

This is why nuke subs are designed in such a way that their water supply and diesal fuel are stored in such a way as to offer shielding along with polymar plastics in the tunnel as the tunnel is behind the aforementioned liquids.

:sunny:

My bad. Obviously I'm no nuclear engineer.

The lead and uranium shield gamma radiation. I've always assumed they shield against neutrons, but looking at various moderators now, they are all relatively light in comparison. Sounds kind of strange that fresh water would be used as shielding, though.