High Temp. Helium

[USMA German]

Hi

 

I am designing a thermodynamic process which uses a Helium/Xenon gas to drive the Turbines. I am not to familiar with Helium and its properties when put under extreme temperatures of around 800 to 1000 C. The biggest concern I have is corrosive effects of the Helium on the material used for the piping. I will be using some alloy of stainless steel to construct the pipes. The danger is if the pipes experience corrosive effects then there will be a leak and this could cause contamination of the thermodynamic (secondary loop).

 

Any help on this would be great! Thank you.

 

Fischhaber

Go Army

Branch: EN

[Martin]

...

I am designing a thermodynamic process which uses a Helium/Xenon gas to drive the Turbines. ...pipes experience corrosive effects then there will be a leak and this could cause contamination of the thermodynamic (secondary loop).

...

 

in the 1970s there was a lot of development in Germany and in the US of the HTGR nuclear reactor that used helium in the primary loop.

 

Indeed I think that the helium of the primary loop may actually have been used directly to drive turbines and generate power

 

In Germany several of the "pebble-bed" type of HTGR reactor were built.

 

these had the nuclear fuel in ceramic balls and the helium coolant would flow up thru the bed and be heated

 

the US type was not quite so successful as the German pebblebed HTGR.

 

the US company involved in HTGR work was "General Atomic" (I believe it was connected with Gulf Oil Company)

 

After the 1970s there was a decline in nuclear power plant orders and a decline in development.

 

helium is a very good coolant. (one of the least corrosive you can have)

 

technically the HTGR ("high temperature gas-cooled reactor") was very promising as a replacement for the Light Water reactor.

 

the pebblebed reactor has some excellent safety features

 

also the high temperature leads to high thermodynamic efficiency.

 

unfortunately all the information I have seen about this is OLD and I do not know of anything on line too help you.

If you have a nuclear engineering library at USMA then go look up

under keyword HTGR. These things were built at one time, and indeed may still be in operation in Germany!

[Martin]

here are some links.

I do not recommend them but they may give something

 

http://www.nuke.hun.edu.tr/english/links/htgr.html

 

http://www.picosearch.com/cgi-bin/ts0.pl?index=40882

 

http://www.iaea.org/inis/aws/htgr/abstracts/

(this actually looks very good to me!)

 

the IAEA (Vienna) is a good organization. this looks like a very useful page about HTGR. but I do not have time to try it for you. you must check it out

 

WOW! look at this:

http://www.iaea.org/inis/aws/htgr/abstracts/abst_te_1382_web.html

there is actually performance reports available online!

 

Remember that these advanced HTGR use HELIUM

so they are relevant to your project

you should read some about them, I think

[jdurg]

Helium is a 100%, completely inert gas. It will not react with anything. Xenon is also an inert gas which will only react with pure fluorine under certain conditions. You have nothing to worry about in regards to your piping corroding upon exposure to helium and/or xenon.

[Tetrahedrite]

Helium is a 100%, completely inert gas. It will not react with anything. Xenon is also an inert gas which will only react with pure fluorine under certain conditions. You have nothing to worry about in regards to your piping corroding upon exposure to helium and/or xenon.

Ahhhh...... the old XeF6 molecule.....a chemistry teacher's best friend

[budullewraagh]

Helium is a 100%, completely inert gas. It will not react with anything. Xenon is also an inert gas which will only react with pure fluorine under certain conditions. You have nothing to worry about in regards to your piping corroding upon exposure to helium and/or xenon.

sorry but i have to nitpick a little. xenon can form the difluoride, tetrafluoride (hydrolyzes to form Xe, O2, HF and XeO3), hexafluoride (hydrolyzes to form XeOF4 and XeF4 and trioxide (used in lights). also, perxenates do exist, for example.

 

i also would like to add that helium isn't going to react with things, unless you want to call an alpha particle "helium"

[jdurg]

sorry but i have to nitpick a little. xenon can form the difluoride' date=' tetrafluoride (hydrolyzes to form Xe, O2, HF and XeO3), hexafluoride (hydrolyzes to form XeOF4 and XeF4 and trioxide (used in lights). also, perxenates do exist, for example.

 

i also would like to add that helium isn't going to react with things, unless you want to call an alpha particle "helium"[/quote']

 

 

Ummmm............ okay? (Just wondering what it is you're questioning. ) I also agree that helium won't reaction with anything. That's what my first sentence says. And I just said that xenon will react with pure fluorine. What it creates really depends on the reaction conditions.

[budullewraagh]

i was just noting the fact that xenon forms oxides

[Babbler]

i was just noting the fact that xenon forms oxides

 

Yes, but it react with oxygen only at several kilobars of pressure. The poster neved said anything about pressures. And the componds are toxic as well.

[budullewraagh]

i will reiterate: "i was just noting the fact that xenon forms oxides"

 

yes, it requires significant amounts of pressure and i never doubted this. i was just "noting the fact," as said multiple times above. yes i know that any compound containing oxidized "inert" gases makes for an incredibly strong oxidizing agent. thank you anyway

[USMA German]

Helium maybe a noble gas however it is a small element.

 

Babbler, you mentioned that Xenon can react under extreme pressures.

 

What about Helium under extreme temperatures of 800 to 1000 C. Pressure in the system can be assumed minimal. However, temperature is the major concern.

 

How does Helium react with metals under high temperatures.

 

Thanks!

 

Fischhaber

Go Army

Branch: EN

[Martin]

...

 

How does Helium react with metals under high temperatures.

...

 

I think the verdict is that it doesnt, even at 1000 celsius

[Martin]

if part of your assignment is to worry about corrosion then maybe you should worry about fissionproducts leaking out of the fuel-cladding and contaminating the helium with traces of more corrosive elements.

 

pure helium by itself is not likely to be a problem.

[USMA German]

Yeah fission products is not a concern. However, neutrons can cause pitting in certain types of metals inside the containment facility but this can be resolved by choosing certain materials which brings me to a new question.

 

I would like to reduce the amount of neutron pitting that will occur on the containment facility walls. Is there a chemical compound which absorbs neutrons.

 

Thanks

 

Fischhaber

Go Army

Branch: EN

[jdurg]

Although it's kind of drastic, Uranium 238 is VERY good at reflecting neutrons back into whatever generated them. In fact, in nuclerar fission devices they generally tend to encase the fission area with a shell of U-238 to direct any stray neutrons back into main critical mass. It's kind of neat how Uranium itself is radioactive, but it's one of the best shields against the more harmful forms of radiation. (Providing that the uranium is U-238).

 

Also, to reiterate again, Helium will not react with anything. There are no temperatures and/or pressures attainable by mankind that will cause helium to react. The only 'reaction' I know of with helium is a fusion reaction deep inside the stars.

[USMA German]

Your are right. U238 reflector is called a tamper on a nuclear fission devise. It allows the devise to produce a greater yeild because more of the fuel will be burned up. They first wanted Gold as the tamper but discovered U238 gains better results.

[jdurg]

It's actually a brilliant maneuver by the government in terms of cost-effectiveness. Sure they could have used gold, but that would cost quite a bit of money. They were already separating the U-238 from the U-235 to make the fissionable material, so why not make good use of the 'waste' product? You have to give them a bunch of credit for that. (In a somewhat twisted kind of way).

[swansont]

Yeah fission products is not a concern. However' date=' neutrons can cause pitting in certain types of metals inside the containment facility but this can be resolved by choosing certain materials which brings me to a new question.

 

I would like to reduce the amount of neutron pitting that will occur on the containment facility walls. Is there a chemical compound which absorbs neutrons.

 

Thanks

 

Fischhaber

Go Army

Branch: EN[/quote']

 

 

Boron-10 is used as a reactor "poison" but only absorbs one neutron (and is thus a "burnable" poison). Gadolinium also, I think.

 

Hafnium is used in control rods because it has several stable isotopes that all have reasonable cross-sections for neutron capture, so any one nucleus can absorb several neutrons. Cadmium-Indium-Silver is also used; Cd-113 has a large thermal cross-section while the other materials have signifcant resonance capture cross-sections.

 

Go Navy