Integral Fast Reactor ???
he...@link.physchem.kth.se
Would someone please be able to briefly explain the concept of the IFR
(Integral Fast Reactor) I keep hearing about whilst reading this newsgroup.
Also, what makes this rector design inherently safe and how does it differ from
conventional fast breeder reactors ?
Feel free to point me in the direction of an article if you like.
Kind Regards
James Crawford
T Orth FP/207/ 8505
The IFR reactor is first a pool type reactor which uses liquid sodium as
coolant. Within the pool is a primary to secondary heat exhanger which is
sodium to sodium. There are actually two on each side of the reactor and they
sit above the level of the core, which is a relatively small part of the
pool. From thise secondary loop, heated sodium is circulated through a
secondary (sodium to water) heat exchanger. The resulting steam is used in
a conventional steam cycle. The sodium is used due to its low neutron
moderation cross-section and extremely high thermal conductivity properties.
Fast reactor cores have a high power density, so efficient operation requires
the ability to carry heat away rapidly. Sodium fills these needs.
The safety advantages of sodium are 1) it can be maintained at atmoshpheric
pressure without boiling at operating temperature, thus eliminating the need
for a pressure vessel of the type in LWR's. 2) The pool type design means that
the primary coolant never leaves the pool, and therefore can't leak out of
a pipe or some other contrivance, and since the heat exchangers are above the
level of the core, it cannot become uncovered even if it did leave the core,
(which it cannot). 3) The sodium pool has so much thermal inertia that in the
event of an accident, the pool can handle all of the heat produced simply by
absorbing it and natural convection (high specific heat+high thermal
conductivity).
The fuel system is metal as opposed to oxide which is the conventional fuel.
There are some historic reasons why oxide was developed over metal originally
for the power industry, but I won't get into those here. Suffice it to say
that IFR fuel has been demonstrated to be meltdown proof in EBR-II, which is
the test reactor for IFR fuel, and similar to what an actual IFR would be like.
The mechanisms here are that metal fuel expands during over power transients
(accidents), + the whole core expands (geometrically larger with the same number
of fissile atoms) thus reducing reactivity. This effect is large enough in a
fast reactor (very sensitive to geometry) that the fission reaction shuts down
at these temperatures. This feature was demonstrated in 1986 in a series of
experiments. The two main ones were loss of heat sink and loss of primary
flow. In all cases, the reactor shut itself down by the afore mentioned
mechanisms, and the high thermal conductivity of metal (10 times greater than
oxide) combined with the thermal properties of sodium kept the reactor within
operating guidelines, and well below the boiling point of the sodium at
standard pressure.
This is what is meant by inherently safe. The reactor controls itself without
human intervention in accident situations. The idea is that, instead of
relying on sohpisticated backup machines and operator analyses/judgement and
then proper action, make the machine "inherently" safe so to speak.
The IFR is now in the stage of testing the fuel recycling phase, and
subsequently testing the recycled fuel in the reactor. Calculations have been
made to determine the effects of high levels of waste in the fuel on
neutronics etcetera, but we need to see some actual experiments. Also, we need
to try the proposed fuel cycle with "hot" fuel, to test the equipment and
procedures for handling it. Also, we are interested in recycling commercial
reactor waste, as well as weapons grade plutonium from the defense industry.
To answer your question about breeders. Fast reactors can usually be operated
in a breeding mode by surrounding the reactor with a U238 "blanket" that absorbs
the neutrons which leak out to produce Pu239. Actually, it first becomes
neptunium 239 and beta decays to Pu239 after a few days. Plutonium production
occurs in all reactors which have U238 in them, but fast reactors, due to
their neutronics, can actually breed more Pu239 than the U235/Pu239 that they
consume. The IFR is different from most breeders because of it's metal fuel
system explained earlier. The French are currently using an oxide system.
Japan is interested in the metal system as well, but is currently using an
oxide system as well. However it is jointly involved with the IFR program
testing mixed-oxide fuels in EBR-II in Idaho.
Tom Orth
Nuclear Engineer
Fuels and Engineering
Experimental Analyses Section
Argonne National Laboratory
Speaking for myself
or...@flicker.fp.anl.gov
Don T. Borowski
: The IFR reactor is first a pool type reactor which uses liquid sodium as
: coolant. Within the pool is a primary to secondary heat exhanger which is
: sodium to sodium. There are actually two on each side of the reactor and they
: sit above the level of the core, which is a relatively small part of the
: pool. From thise secondary loop, heated sodium is circulated through a
: secondary (sodium to water) heat exchanger. The resulting steam is used in
: a conventional steam cycle.
Could you explain what is done to make sure that heat exchange at the
secondary sodium/water interface is done safely? Obviously, I am
thinking here of what happens if the heat exchanger develops a crack.
Donald Borowski WA6OMI Hewlett-Packard, Spokane Division
"Angels are able to fly because they take themselves so lightly."
-G.K. Chesterton
John De Armond
>The fuel system is metal as opposed to oxide which is the conventional fuel.
>There are some historic reasons why oxide was developed over metal originally
>for the power industry, but I won't get into those here. Suffice it to say
>that IFR fuel has been demonstrated to be meltdown proof in EBR-II, which is
>the test reactor for IFR fuel, and similar to what an actual IFR would be like.
>The mechanisms here are that metal fuel expands during over power transients
>(accidents), +the whole core expands (geometrically larger with the same number
>of fissile atoms) thus reducing reactivity. This effect is large enough in a
>fast reactor (very sensitive to geometry) that the fission reaction shuts down
>at these temperatures. This feature was demonstrated in 1986 in a series of
>experiments. The two main ones were loss of heat sink and loss of primary
>flow. In all cases, the reactor shut itself down by the afore mentioned
>mechanisms, and the high thermal conductivity of metal (10 times greater than
>oxide) combined with the thermal properties of sodium kept the reactor within
>operating guidelines, and well below the boiling point of the sodium at
>standard pressure.
Tom, I have to take great exception to this kind of party line propaganda.
There are a number of us nukes who have been active in this group
for years who don't want to see our credibility destroyed by
propagandizing. Specifically,
* Neither oxide nor metal fuel is "meltdown-proof". "Meltdown" has
become a loaded term and must be used carefully. Either type
of fuel will melt from decay heat given loss of cooling for a
reasonable interval after shutdown.
* Negative temperature coefficient cores are certainly not unique to
metal fueled fast reactors. Thermal and void coefficients
in thermal reactors are at least as effective a self-regulation
mechanism.
* Fast reactors bring their own set of safety concerns that should
not be glossed over when trying to convince the skeptics.
* The IFR's intrinsically safe cooling system's properties are at
best only obliquely related to fuel type. Munging fuel and
coolant properties together as you did above does not serve
the purpose very well.
* Stating that a particular fuel or core is "meltdown-proof" is
false on its face to anyone with rudimentary knowledge of nuclear
reactors. Stating so destroys your credibility.
You need to think long and hard about your credibility in this forum.
You went off half-cocked on the Freon issue and you're propagandizing
on this topic. The IFR may be the best thing since sliced bread but
no one will believe you if you continue using hype and are fast and
loose with the facts.
John
--
John De Armond, WD4OQC | For a free sample magazine, send
Performance Engineering Magazine(TM) | a digest-size 52 cent SASE
Marietta, Ga "Hotrods'n'computers" | (Domestic) to PO Box 669728
j...@dixie.com "What could be better?" | Marietta, GA 30066
P Angelo /RA/208G/osra 7550
>or...@salt.ra.anl.gov (T Orth FP/207/ 8505) writes:
>
>>The fuel system is metal as opposed to oxide which is the conventional fuel.
>>There are some historic reasons why oxide was developed over metal originally
>>for the power industry, but I won't get into those here. Suffice it to say
>>that IFR fuel has been demonstrated to be meltdown proof in EBR-II, which is
>>the test reactor for IFR fuel, and similar to what an actual IFR would be like.
>>The mechanisms here are that metal fuel expands during over power transients
>>(accidents), +the whole core expands (geometrically larger with the same number
>>of fissile atoms) thus reducing reactivity. This effect is large enough in a
>>fast reactor (very sensitive to geometry) that the fission reaction shuts down
>>at these temperatures. This feature was demonstrated in 1986 in a series of
>>experiments. The two main ones were loss of heat sink and loss of primary
>>flow. In all cases, the reactor shut itself down by the afore mentioned
>>mechanisms, and the high thermal conductivity of metal (10 times greater than
>>oxide) combined with the thermal properties of sodium kept the reactor within
>>operating guidelines, and well below the boiling point of the sodium at
>>standard pressure.
>
>Tom, I have to take great exception to this kind of party line propaganda.
>There are a number of us nukes who have been active in this group
>for years who don't want to see our credibility destroyed by
>propagandizing. Specifically,
John, I think you are debating semantics. Refer to Fistedis' book
Demonstration of the Inherrent Safety of the IFR using EBR-II, 1986
North Holland pub. This is an account of the battery of tests called
SHRT (sounds like shirt), which proved the inherrent safety of the reactor
core. The metal fuel concept IS the technology because it lends itself to
core expansion (in fuel region) and also electrorefining/recast into new
fuel.
>
>* Neither oxide nor metal fuel is "meltdown-proof". "Meltdown" has
> become a loaded term and must be used carefully. Either type
> of fuel will melt from decay heat given loss of cooling for a
> reasonable interval after shutdown.
>
Yes but I think in context, meltdown refers to the act of destroying fuel
(or clad breach) while undergoing some sort of transient. Granted decay heat
is a consideration, but the configuration of EBR-II as a pool type reactor,
prohibits the transfer of fuel out of the reactor until an acceptable level
of decay heat is achieved. Note: the EBR-II reactor has a sucessful operating
record of over 30 years!!!! Also, after a reactor run, a subassembly is
removed to a storage basket, located next to the core, and also contained in
the same pool vessel. Thus fuel handling OUT of the basket is accomplished by a
Fuel Unloading Machine (FUM),under constant coolant. In this case, it
is an argon gas flowing through the FUM. Loss of cooling accidents under
fuel transfer have been analyzed and have not contributed to degradation of
safety/fuel integrity.
>* Negative temperature coefficient cores are certainly not unique to
> metal fueled fast reactors.
To my knowledge, the IFR is the ONLY metal fueled fast reactor concept
either in operation or demonstration. Please do not refer to the current
crop of FBRs as metal fueled. This is why the IFR was conceived in the
early 80's; to handle ALL questions Clinch River BR could not.
> Thermal and void coefficients
> in thermal reactors are at least as effective a self-regulation
> mechanism.
>
I think you miss the importance of axial expansion fuel growth wrt reactivity
effects. Numerous experiments loaded in the EBR-II core have demostrated the
fuel expansion reactivity effects, and this is supported by the calculations.
I also think you are missing the point that because of a harder spectrum
the overridding coefficient is doppler broadening.
>* Fast reactors bring their own set of safety concerns that should
> not be glossed over when trying to convince the skeptics.
>
I think the skeptics pull everything out of the air, from trying to equate
fast reactors to bombs, to misunderstanding the concept of why a fast
reactor is unique (than LWRS, or other types)
>* The IFR's intrinsically safe cooling system's properties are at
> best only obliquely related to fuel type. Munging fuel and
> coolant properties together as you did above does not serve
> the purpose very well.
>
Again this is wrong. The IFR as a reactor has yet to be built .The cooling
system as you refer to is in reality, a very large inventory of sodium in the
reactor tank (remember EBR-II is the reactor used to demonstrate IFR fuel)
which has demonstrated (remember the SHRT tests) core cooling even with
the primary pumps turned off.
>* Stating that a particular fuel or core is "meltdown-proof" is
> false on its face to anyone with rudimentary knowledge of nuclear
> reactors. Stating so destroys your credibility.
>
I think Tom was stating the facts as presented in the literature. You should
really understand the context by which he refers to. I believe that to
state a reactor is "meltdown-proof" in its entirety is like stating an airplane
is "crash-proof". In this context, it is obsurd to think an airplane is
designed to crash. If you consider the absolute possibility that an accident
can happen, well that discussion has been beat like a dead horse.
The main point is that "melt-down" proof simply refers to the fact that
the fuel will 1)never be uncovered as long as it remains in the pool
2) That transients such as over-power,loss of flow,loss of heat-sink, can not
contribute to anomolous fuel behavior, due to the fact that the metal fuel
alloy, could release its energy to the coolant before centerline temperatures
ever get to alloy melt temperatures (this also has been demonstrated)
>You need to think long and hard about your credibility in this forum.
>You went off half-cocked on the Freon issue and you're propagandizing
>on this topic. The IFR may be the best thing since sliced bread but
>no one will believe you if you continue using hype and are fast and
>loose with the facts.
>
>John
>--
>John De Armond, WD4OQC | For a free sample magazine, send
>Performance Engineering Magazine(TM) | a digest-size 52 cent SASE
>Marietta, Ga "Hotrods'n'computers" | (Domestic) to PO Box 669728
>j...@dixie.com "What could be better?" | Marietta, GA 30066
I believe Dr.Orth is very credible in this forum. Now, with respect to
the IFR, I believe it is the next best thing to sliced bread, provided that
bread continues to be buttered by the money necessary to keep the technology
viable. I know you have DOE and LWR experience. I too share the same background.
However, whereas I see the donut, you see the hole. I think that in this forum
it is clear who is credible and who is not (Mr.Yodaiken). Credibility has a lot
to do with perception, and it is something that the net lacks the capability
to discern.
Peter Angelo
On my soapbox-by myself
pan...@anl.gov
T Orth FP/207/ 8505
maintained at approximately atmoshperic pressure. Any cracks in the heat
exchanger would result in water forced into the sodium side, and not the
other way around. This sodium loop is furthermore non-radioactive. Your
concerns about the chemical reactivity of sodium and water are well founded,
although an accident of this type would 1) be a non-nuclear accident, and 2)
be contained do to the pressure gradient, and 3) would be minimal due to a
lack of sufficient oxygen to sustain a reaction.
Tom Orth
Nuclear Engineer
Fuels and Engineering
Experimental Analysis Section
T Orth FP/207/ 8505
|> Tom, I have to take great exception to this kind of party line propaganda.
|> There are a number of us nukes who have been active in this group
|> for years who don't want to see our credibility destroyed by
|> propagandizing. Specifically,
|>
|> * Neither oxide nor metal fuel is "meltdown-proof". "Meltdown" has
|> become a loaded term and must be used carefully. Either type
|> of fuel will melt from decay heat given loss of cooling for a
|> reasonable interval after shutdown.
You're reading way too much into my statements. The fuel was demonstrated
meltdown proof in the conditions in which I described. They were the loss of
flow and loss of heat sink without scram tests. Certainly, without adequate
decay heat removal the fuel will melt. The claim here is that there is adequate
heat removal in these conditions.
|>
|> * Negative temperature coefficient cores are certainly not unique to
|> metal fueled fast reactors. Thermal and void coefficients
|> in thermal reactors are at least as effective a self-regulation
|> mechanism.
Of course negative temperature coefficient cores aren't unique to metal fueled
fast reactors. I didn't say that did I? I simply described the dominant effect
in overpower transients. The void coefficient requires sodium boiling or
bubbling btw. This didn't occur in the over power tests, therefore the thermal
expansion and doppler broadening were the dominant effects in those scenarios.
Finally, the thermal expansion characteristics are part of the overall thermal
coefficient. Thermal coeficients are the result of the interactions of coolant
,moderatoer and fuel, not just coolant.
|> * The IFR's intrinsically safe cooling system's properties are at
|> best only obliquely related to fuel type. Munging fuel and
|> coolant properties together as you did above does not serve
|> the purpose very well.
I didn't suggest that the cooling systems properties were related to fuel type.
I discussed these as a separate issue. However, the peak temperature seen by
the fuel is much lower than that for oxide fuel due to the thermal conductivity
of the metal. Furthermore, after a certain degree of burnup, the fission
gas bubbles interconnect in the fuel and release the gas to the plenum of the
fuel pin. This interconnectivity allows the bond sodium to fill the voids, thus
increasing the fuel thermal conductivity at that point. So, when the fuel is
100% dense, it has high thermal conductivity which slowly decreases until
interconnectivity of fission gas bubbles, at which time it deceases again to
roughly the same value as it's as built value.
|>
|> * Stating that a particular fuel or core is "meltdown-proof" is
|> false on its face to anyone with rudimentary knowledge of nuclear
|> reactors. Stating so destroys your credibility.
To say that it is "meltdown proof" period is false. But, that's not what I said.
I said that in the experiments that were done, it was proven to be meltdown
proof under those conditions. Once again, you have chosen to read into what
I have said
|>
|> You need to think long and hard about your credibility in this forum.
|> You went off half-cocked on the Freon issue and you're propagandizing
|> on this topic. The IFR may be the best thing since sliced bread but
|> no one will believe you if you continue using hype and are fast and
|> loose with the facts.
|>
I never claimed to be an expert on Freon, and I still don't claim to be. I
was reporting the results of an article that I had read about the law in 95 that
would ban certain CFC's. This is an entirely different kind of topic..one
related to laws and economics, not technical CFC issues or nuclear reactors.
Furthermore, I haven't been fast and loose with the facts regarding the IFR,
but you have chosen to ignore all of the parts of my article which dealt with
the issues you have raised here. Further, suggesting that the void coeficient
is more meaningful in the loss of flow and loss of heat sink scenarios tested
in 86 shows your general lack of understanding of the experiments.
|> John
|> --
|> John De Armond, WD4OQC | For a free sample magazine, send
|> Performance Engineering Magazine(TM) | a digest-size 52 cent SASE
|> Marietta, Ga "Hotrods'n'computers" | (Domestic) to PO Box 669728
|> j...@dixie.com "What could be better?" | Marietta, GA 30066
I don't know what your agenda is here. Especially regarding the freon issue.
I don't see what that has to do with a technical issue like this one. But
purposefully ignoring key phrases in my article and then claiming that I
ignored it is close to maligning my character. I also object to your tone.
Additionally, anyone who is willing to read the article carefully will see that
I haven't ignored the things which you have claimed I have. Hopefully this
response clears that up.
Tom Orth
Nuclear Engineer
E. Michael Smith
Tom, John, can you two guys call a truce? Watching two pro-nukes
go at each other ('They were in violent agreement at the top of
their lungs!' comes to mind...) is more than an aging Friend of The Earth-er
can handle!
In article <CBLqs...@mcs.anl.gov> or...@salt.ra.anl.gov (T Orth FP/207/ 8505) writes:
>
John De Armond wrote:
>|> Tom, I have to take great exception to this kind of party line propaganda.
>|> There are a number of us nukes who have been active in this group
>|> for years who don't want to see our credibility destroyed by
>|> propagandizing. Specifically,
Technical nit harvesting deleted... along with the nit spray...
John was just warning you that there are a bunch of leaches and sharks
in these waters and that he has the scars to prove it. (Heck, I think
I may have even put one or two tinsy ones somewhere on his thick hide ;-)
So be carefull when you jump in the water...
>|> You need to think long and hard about your credibility in this forum.
>|> You went off half-cocked on the Freon issue and you're propagandizing
>|> on this topic. The IFR may be the best thing since sliced bread but
>|> no one will believe you if you continue using hype and are fast and
>|> loose with the facts.
>I never claimed to be an expert on Freon, and I still don't claim to be. I
>was reporting the results of an article that I had read about the law in 95 that
>would ban certain CFC's. This is an entirely different kind of topic..one
Well, I have to side with John here. Credibility gets dented when you
make a mistake, in your field or not. He is trying to make sure you
stay a strong and TRUSTED voice on his side of the debate - pro nuke.
>related to laws and economics, not technical CFC issues or nuclear reactors.
>Furthermore, I haven't been fast and loose with the facts regarding the IFR,
>but you have chosen to ignore all of the parts of my article which dealt with
>the issues you have raised here. Further, suggesting that the void coeficient
>is more meaningful in the loss of flow and loss of heat sink scenarios tested
>in 86 shows your general lack of understanding of the experiments.
John understands them. He was just pointing out that there are a BUNCH
of folks who will take any minor glossing over of a minor technical nit
and use it to bludgion you. Heck, after about 6 months of needling, I
finally got John to admit that yes, you could make a nuclear bomb from
'reactor grade' plutonium. It'd likely be a fizzle yield and kill you
from exposure before you could set it off, but it COULD be done. He had
made the 'mistake' of being reasonable and simply stating the truth that
it isn't practical, but used the word 'impossible' (or something close...)
rather than taking twenty pages to say in detail that it was theoretically
possible but one of the most brain dead things someone could try.
Why did I spend 6 months after that needling him over the
fact that he had not been quite exactly and excruciatingly precise?
Heck, I donno any more... I was more anti-nuke then, I guess...
...
>I don't know what your agenda is here. Especially regarding the freon issue.
To warn you about bored sharks looking for a free lunch on some
minor trivial error you make in a public forum....
>I don't see what that has to do with a technical issue like this one. But
>purposefully ignoring key phrases in my article and then claiming that I
>ignored it is close to maligning my character. I also object to your tone.
>Additionally, anyone who is willing to read the article carefully will see that
>I haven't ignored the things which you have claimed I have. Hopefully this
>response clears that up.
Please back down the escalation level, both of you guys, OK?
John wasn't being a bad boy, he was just hinting at what folks
with a strong anti-nuke agenda would do with your posting... Giving
you a gentile idea how it would be attacked by all the anti-nukes.
I've played both sides of the fence some, so I can appreciate John's
actions a bit more, I guess... When I first started reading sci.energy
(gads, a decade ago?... sigh...) I was a moderately anti-nuke. Over
the years of debate I've been moved to a moderately pro-nuke (or at
least nuke-tolerant) (and it's all John's fault ;-) All he was doing
was, seeing you were a bit 'new on the block' and were 'on his side'
of the debate, offering a bit of friendly advice about how to save
yourself some grief... and I'd suggest listening to the 'ol one eyed
dog when he talks about the local scruffy cats ;-)
Now can we get back to the usual pro vs anti nuke debate? This
pro vs pro nuke debate could get someone educated about how a nuke works! ;-)
--
E. Michael Smith e...@apple.COM
'Whatever you can do, or dream you can, begin it. Boldness has
genius, power and magic in it.' - Goethe
I am not responsible nor is anyone else. Everything is disclaimed.
Michael Moroney
>|> Could you explain what is done to make sure that heat exchange at the
>|> secondary sodium/water interface is done safely? Obviously, I am
>|> thinking here of what happens if the heat exchanger develops a crack.
>|>
>The steam side is maintained at high pressure, whereas the sodium loop is
>maintained at approximately atmoshperic pressure. Any cracks in the heat
>exchanger would result in water forced into the sodium side, and not the
>other way around. This sodium loop is furthermore non-radioactive. Your
>concerns about the chemical reactivity of sodium and water are well founded,
>although an accident of this type would 1) be a non-nuclear accident, and 2)
>be contained do to the pressure gradient, and 3) would be minimal due to a
>lack of sufficient oxygen to sustain a reaction.
You don't need external oxygen for excitement to happen. Hot sodium is
more than sufficiently active to rip the oxygen right out of water, producing
hydrogen, lye and much heat.
-Mike
T Orth FP/207/ 8505
|>
|> E. Michael Smith e...@apple.COM
|>
|> 'Whatever you can do, or dream you can, begin it. Boldness has
|> genius, power and magic in it.' - Goethe
|>
|> I am not responsible nor is anyone else. Everything is disclaimed.
Thanks for the advice both of you. Any way you can help me break this
net news addiction? Does it die down after a while?
T Orth FP/207/ 8505
Steam generator leaks are usually pretty small, but you're right, sodium is
much more active in water than it is in air.
Another question came to me via email about sodium as a choice of coolant.
Lead has been suggested, but due to its weight, special pumping problems
occur. I don't know what the status is on this.
Sodium disposal came up as well. The half lives of the activations in sodium
are short for those with large activation cross-sections, and on the order of
2 years for the less major ones. Activation isn't a problem. I think for
disposal or storage the proposed methods range from forming a salt with it to
forming oxides of some kind to stabilized it chemically. This is out of my
area though, so if any one can help me out here I'd appreciate it.
Also, why were oxides chosen over metals originally? Metal fuel grows a lot
during irradiation, and the mechanisms for this growth were poorly understood
in the beginning. The metal would swell and strain axially and radially, and
in the first designs, it would push up against the cladding and rip it open.
The solution was simply to give the fuel enough room to grow, and eventually it
stopped swelling after it had grown about 30 %. Also, although metal fuel has
a much higher thermal conductivity than oxide, it also has a lower melting
temperature, and undergoes phase changes across the thermal gradient, and
perhaps during transients, startup, or shutdown. It turns out that the thermal
conductivity is sufficient to makeup for this lower melting temperature.
The main effect that kept metals out of the mainstream was primarily the
growth which limited the burnup. There is disagreement on this though, as some
would argue it was melting temperature.
So, obviously metals would need some development. Oxides were quick and
relatively easy to develop, although their promise for efficiency etcetera was
limited for the future. Why didn't we put the effort into metal then?
It goes back to Admiral Rickover's selection of a navy reactor. The reactor had
to be compact, and quick and easy to develop. This left out almost every design
save the LWR with ceramic fuels. When it came time to commercialize, that is
where we had experience, and so that's what we built. Simple as that.
ref (Joseph G. Morone, Edward J. Woodhouse, "The Demise of Nuclear Energy?"
Yale University Press)
So, different alloys have
been played with over the years, primarily in EBR-II. The current IFR fuel
is something like U-19Pu-10Zr by weight percent. There may be better ones out
there, better alloying elements than Zirc for example, but we'll probably never
know. Operating experience and the experiments that I have looked at show
operational reliability of this alloy and alloys similar to it to be completely
reliable up to burnups close to 20%.
The IFR is not the only plutonium burning concept out there. Mixed oxides in
LWR's have been proposed, as well as mixed oxides (MOX) in fast reactors.
The rate of burning in all of these concepts depends on the percentage of
Pu you can cast into the fuel. The main benefit in the short term would be
simply that you are activating it and mixing it with other fission products/
actinides, thus making it diversion resistant.
Tom Orth
Nuclear Engineer
Gary Coffman
>|>
>|> Could you explain what is done to make sure that heat exchange at the
>|> secondary sodium/water interface is done safely? Obviously, I am
>|> thinking here of what happens if the heat exchanger develops a crack.
>|>
>|> Donald Borowski WA6OMI Hewlett-Packard, Spokane Division
>|>
>maintained at approximately atmoshperic pressure. Any cracks in the heat
>exchanger would result in water forced into the sodium side, and not the
>other way around. This sodium loop is furthermore non-radioactive. Your
>concerns about the chemical reactivity of sodium and water are well founded,
>although an accident of this type would 1) be a non-nuclear accident, and 2)
>be contained do to the pressure gradient, and 3) would be minimal due to a
>lack of sufficient oxygen to sustain a reaction.
Actually,
1) This should be a designed for contingency.
2) It will be *driven* by the pressure gradient.
3) Sodium is sufficiently reactive with water that it rips the
oxygen from the molecule generating hydrogen gas, lye, and
a lot of heat.
Now the heat isn't necessarily a major problem, this is a heat
exchanger after all. The lye is a contaminant, but it's less
reactive than the regular working fluid so that shouldn't present
major problems either. The hydrogen gas could be a problem, but as
you note, there's no free oxygen present in the heat exchanger.
While removing the hot hydrogen could be tricky, it won't necessarily
cause an explosion.
The real problem depends on the magnitude of the break. Cracks that
weep a bit would just be a nuisance. Major guillotine breaks would
put the heat exchanger out of action and likely cause a large
pressure transient in the heat exchanger and the steam system piping.
If the systems aren't designed to contain this transient, *then* you'd
have an accident rather than just a contingency fault requiring shutdown
and repair.
Gary
--
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E. Michael Smith
>
>Thanks for the advice both of you. Any way you can help me break this
>net news addiction? Does it die down after a while?
Yeah, eventually you die, and then a bit later someone at work notices
and turns off your terminal, then you stop reading net news ... ;-)
Seriously, though, folks tend to go through cycles. Eventually most
folks swear off of most groups and persist in haunting only one or two.
Every so often those folks take a few months break. You can quit any
time you want. Heck, I've done it dozens of times ... Only a few people
end up consumed by it longer than the first year...
--
P Angelo /RA/208G/osra 7550
[good stuff deleted]
>limited for the future. Why didn't we put the effort into metal then?
>It goes back to Admiral Rickover's selection of a navy reactor. The reactor had
>to be compact, and quick and easy to develop. This left out almost every design
>save the LWR with ceramic fuels. When it came time to commercialize, that is
>where we had experience, and so that's what we built. Simple as that.
>ref (Joseph G. Morone, Edward J. Woodhouse, "The Demise of Nuclear Energy?"
>Yale University Press)
Professor Morone is on faculty at RPI in Troy,NY. I remember when his book
came out and he held a seminar. Alot of management (energy policy makers) and
nuclear engineers were in attendance. His talk did emphasize that Rickover's
legacy was to doom the commercial nuclear industry to an offshoot of the
Navy's. I don't know who was booed more, he or Sterglass. His point was
left unfufilled when he posed no real solution for commercial nuclear, more
like a laizze faire let the market decide.
I do believe that his fundamental premise was correct, since light water
was plentiful as both moderator and coolant to a Navy ship. But these ships
have a different service mission (frequent startup/shutdowns, power ramps
etc.) The first commercial nuclear plant used the old Nautilus core for a
demo.
More importantly, Rickover was also BOTH the AEC and the Navy Nuclear Board
(he could ask himself a Navy question and answer it as an AEC rep)
Hyman Rickover: Lesson in Management (see American Scientist June/July) for
a review
BTW I think that nuclear engineers should be involved more in energy policy
making decisions. It would help only to keep intervenors honest and not let
them ramrod their personal opinions down the public's throat.
Peter Angelo
on my soapbox-alone
pan...@anl.gov
John De Armond
>was reporting the results of an article that I had read about the law n 95 that
>would ban certain CFC's. This is an entirely different kind of topic..one
>related to laws and economics, not technical CFC issues or nuclear reactors.
>Furthermore, I haven't been fast and loose with the facts regarding the IFR,
>but you have chosen to ignore all of the parts of my article which dealt with
>the issues you have raised here. Further, suggesting that the void coeficient
>is more meaningful in the loss of flow and loss of heat sink scenarios tested
>in 86 shows your general lack of understanding of the experiments.
I'm not sure what meaningful means. With both types of cores, intrinsic
self-regulation is designed -in, both cores will shut themselves down
under LOCA conditions and both will melt from residual heat if cooling
remains absent.
>I don't know what your agenda is here. Especially regarding the freon issue.
>I don't see what that has to do with a technical issue like this one. But
>purposefully ignoring key phrases in my article and then claiming that I
>ignored it is close to maligning my character. I also object to your tone.
>Additionally, anyone who is willing to read the article carefully will see that
>I haven't ignored the things which you have claimed I have. Hopefully this
>response clears that up.
My "agenda" (as much as I might ever have one) is to not see you booger
up your credibility by using what amounts to press release language in
this forum. Remember we're on the same side. The Yackadamns (at least
those with some actual technical capabilities) will be far less
kind.
T Orth FP/207/ 8505
|>
|> My "agenda" (as much as I might ever have one) is to not see you booger
|> up your credibility by using what amounts to press release language in
|> this forum. Remember we're on the same side. The Yackadamns (at least
|> those with some actual technical capabilities) will be far less
|> kind.
|>
|> John
Point well taken. However, it seemed like there was a broad cross-section of
readers here. I'm not Chuck Till or Alan Shriesheim, and I'm not talking to
representative so and so from wherever, so I think I gave a good description
in qualitative lay terms. It seemed like you were answering a post that
wasn't made...sort of like a politician attacing a response of his
opponent by totally changing the content of his opponents response. But oh..
sorry, we're on the same side.
BTW, what was the deal with the metal fatigue thing and Yodaiken? I'm still
boggling about that one (metal fatigue = radiation emrittlement?????!!!!)
|>
|> --
|> John De Armond, WD4OQC | For a free sample magazine, send
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Tom Orth