Do 2 Kilowatt Nuclear Reactor Still Exist

[average guy]

i was told that the smallest nuclear reactor power
station is 2 Kilowatts and they take up about
half a city block?
is that correct?
can they be built?

Have A Nice Day!

 

[Simon Bridge]

What makes you think there is a lower limit to the power output to a nuclear power plant?
If nothing else, you could just use a normal one to drive a really really inefficient generator :)

Even sub-critical masses of radioisotopes can produce enough heat to do useful work.

 

[average guy]

simon
your question/answer:
1 i don't know
2 doesn't sound like a good idea.
3 that went over my head.
can a 2 Kilowatt Nuclear Power Generator be
built the size of a city block?

Have A Nice Day!

 

[Pengwuino]

simon
your question/answer:
1 i don't know
2 doesn't sound like a good idea.
3 that went over my head.
can a 2 Kilowatt Nuclear Power Generator be
built the size of a city block?

Have A Nice Day!

2 KW is extremely small in terms of power generation. They sell gasoline generators at the store that you can put in your trunk that will do that. I would be very surprised if you couldn't build a reactor of that size in a very small foot print. There would be considerations for shielding and a lot of other things, but I don't see any theoretical reason why it would not be possible. Hell, how big are nuclear reactors in submarines? They produce a couple dozen megawatts

 

[Simon Bridge]

[after a sleep and a cup of coffee]
I suppose I could break this into two parts:
1. is the historical 2kW plant still running? (which one?)
2. what is the minimum power from a supra-critical core? eg. how far can you damp a critical mass and still have a chain reaction?

close enough?

note: we usually think of a nuclear reactor as like the one in Fukushima and Chernobyl[1] - these exploit a nuclear chain reaction to produce heat to run a steam engine, which is hooked to an electric generator. To get a chain reaction, you need a minimum mass of fuel ... called a "critical mass".

However, the fuel gets warm before it goes critical.
You can get a few tens of grams of plutonium, for eg, and insulate it, and it can get red-hot quite quickly.
You can use this to drive, say, a stirling engine ... or a thermo-couple. These things are normally called nuclear "batteries" rather than reactors but I would argue that this is just spin. "Battery" sounds nicer than "reactor".

Now I could take a nuclear battery and just connect it to something that will glow - so it becomes a nuclear powered light.

One way of doing this, rather than go through a generator and wires and stuff, is to just surround the fissioning material with glass coated with phosphor (or whatever) so it glows when the fission fragments hit it. This is how beta-lights work... from beta-decay (a nuclear reaction). So if I am going to be really general by defining a nuclear power reactor as any machine which generates useful power from nuclear reactions, I'll have to include beta-lights as nuclear reactors. Which may be pushing the definition a tad :)

------------------------
[1] the building you see on the news are much much bigger than the actual reactor itself. Similarly, the "city block" sized plant would just be the building.
iirc the first atomic pile fit comfortably inside a squash court.

 

[russ_watters]

I suppose you could take a thousand megawatt reactor, pull 2 kW off it and dump the other 999,998 kW as waste heat...

 

[Astronuc]

i was told that the smallest nuclear reactor power
station is 2 Kilowatts and they take up about
half a city block?
is that correct?
can they be built?

Have A Nice Day!

I've not heard of a 2 kWe nuclear power plant. Would it be a simple thermal plant for district heating. A capacity of 2 kWe is an appropriate capacity for 1 home. Half a city block would be wasted on 2 kWe.

I'll have to check my records, but the smallest nuclear electrical plant of which I'm aware was Big Rock Point at about 60 MWe.

 

[Simon Bridge]

I suppose you could take a thousand megawatt reactor, pull 2 kW off it and dump the other 999,998 kW as waste heat...

Yeah - the really really really inefficient generator idea.
Just cause you are producing the energy does not mean you have to use it ... but where's the fun in that?

It's been too long since I did any nuclear chain reaction stuff ... not actually being interested in nuclear power (being in NZ and all) at the time.
iirc the reaction rate broadly depends on the range of the fast neutrons v how diffuse the fuel is (and the kind of moderator)? Wasn't there a naturally occurring reactor in prehistory that was very slow?

 

[average guy]

simon
i may have the rating number wrong, it's been more than
8 years since i talked to this person.
what is the smallest true nuclear power plant that
can be built and it's power output?

Have A Nice Day!

 

[Simon Bridge]

define "nuclear power plant"
The Radioisotope thermoelectric generators in spacecraft are of order of 100s of Watts and about man-sized. Voyagers were 470W. Pic from Cassini probe:

... weighs 57kg and outputs 300W

 

[Astronuc]

simon
i may have the rating number wrong, it's been more than
8 years since i talked to this person.
what is the smallest true nuclear power plant that
can be built and it's power output?

Have A Nice Day!

The AGN-201M has a power of 5 W. It's nice for practicing reactor startup, or analyzing neutron source strength, differential rod worth, approach to criticality.

It would be impractical for any power generation.

 

[average guy]

simon
what most people would consider a nuclear power plant.
the guy said it can be built in less than a city block and
it generates electricity and is nuclear powered.

astro nuke
think bigger!

Have A Nice Day!

 

[Schr0d1ng3r]

Well, the research reactor at my school is rated at 5MW(t), and the reactor facility takes up MUCH less than half a block. I know there are SLOWPOKE reactors that run around 20kW(t), so there's no reason that I can see preventing one from making a 2kW(e) nuclear power station in half a block or less. There's just no point...

 

[Pengwuino]

I'll have to check my records, but the smallest nuclear electrical plant of which I'm aware was Big Rock Point at about 60 MWe.

I love it.

 

[average guy]

schroding
sure there is!
there's that 2!
20 kilowatt was probably what he was talking about!
the idea is to have people work at them and
get used to them.
the neighborhood GE Nuclear Power Plant!
sounds like a winner to me!
penguin
what do you love?

Have A Nice Day!

 

[Simon Bridge]

simon
what most people would consider a nuclear power plant.
the guy said it can be built in less than a city block and
it generates electricity and is nuclear powered.

astro nuke
think bigger!

Have A Nice Day!

Oh yeah but there were already others chiming in who knew about the other kinds.
eg Astronuc was checking records...
I think these ones are cool.

Admittedly the AGN-201M probably takes the prize.
http://nuclear.tamu.edu/features/agn/photos/AGNcurrent.jpg
But mine is much cooler to look at xD
I mean it is black and shiny and has fins and it sits in a precision engineered clamp - not some old bits of 2x4... look, it's the porsche of nuclear technology - you don't see any women checking out the AGN in that pic do you? No! Case closed. ;)

 

[Ryan_m_b]

To put the 2KW figure into perspective; I'm sitting next to an electric heater that consumes so much. A "city block" sized reactor to fuel that would indicate a gargantuan waste. IIRC a normal nuclear reactor operates at 1 million times this.

 

[gmax137]

EBR-1 lit four 200W bulbs in 1951, near Arco Idaho. Later it made more power; also famous for melting down.

http://www.roadsideamerica.com/story/2960

http://en.wikipedia.org/wiki/Experimental_Breeder_Reactor_I

etc.

 

[Astronuc]

Well, the research reactor at my school is rated at 5MW(t), and the reactor facility takes up MUCH less than half a block. I know there are SLOWPOKE reactors that run around 20kW(t), so there's no reason that I can see preventing one from making a 2kW(e) nuclear power station in half a block or less. There's just no point...

http://en.wikipedia.org/wiki/SLOWPOKE_reactor

Note "The SLOWPOKE-2 uses 93% (originally) enriched uranium in the form of 28% uranium-aluminum alloy with aluminum cladding." More modern designs would have to use lower enrichment to comply with current anti-proliferation matter.

And " The Chalk River prototype went critical in 1970, and was moved to the University of Toronto in 1971. It had one sample site in the beryllium reflector and operated at a power level of 5 kW. In 1973 the power was increased to 20 kW "

See also - "AECL also designed and built a scaled-up version (2-10 MWth) called SLOWPOKE-3 for district heating at its Whiteshell Nuclear Research Establishment in Manitoba." That's not for electrical generation.

And finally - "SLOWPOKE reactors are used mainly for neutron activation analysis (NAA), in research and as a commercial service, but also for teaching, training, irradiation studies, neutron radiography (at the Royal Military College of Canada) and the production of radioactive tracers."

 

[average guy]

physics forum members
is the gist of this that there's an
'economics of scale' where it is
better to just build a full size one
for generating electricity?

Have A Nice Day!

 

[Astronuc]

physics forum members
is the gist of this that there's an
'economics of scale' where it is
better to just build a full size one
for generating electricity?

Have A Nice Day!

Economics is a key part of it, and to some extent, when dealing with nuclear, so is safety.

When developing an electrical power generating system, one must consider the thermodynamic efficiency as well as cost. One has to consider choices like the thermodynamic cycle, e.g., Rankine (steam - or really 2 phase liquid/vapor), Brayton (gas), Stirling (gas), Kalina (steam/ammonia), thermoelectric, or combinations thereof, e.g. combined cycle such as Brayton/Rankine.

The objective of the designer is to develop a cost effective solution. If one can build a system for $500/kWe, it makes no sense to build a system for $1000/kWe or $5000/kWe.

One has to consider the capital cost, the cost of interest on that capital, assuming one uses debt to finance construction, the operational and maintenance cost, the fuel cost, and the waste disposal cost (as distinct from other O&M costs).

 

[Caniche]

Just how do you work out the cost of a statistically predictable catastrophic accident? Any loss adjusters out there?

 

[jim hardy]

the Army built one that goes on a flatbed trailer truck. its intent was to make power for mobile communications centers back in the vacuum tube days..

i am told one of them provided power for the early Antarctic research station. it had advantage that they didn't have to haul in boatloads of diesel fuel and dispose of the empty drums..

google words 'los alamos godiva flattop' and you'll fnd lots of infrmation about many very odd reactors that were built in the R&D days.

Godiva was a low power unshielded (i.e. naked) reactor used for among other things studying effect of radiation on rats. (now there's one for political thread...)

as to someone's question what is minimum power level for sustained chain reaction -

practical limit would be enough neutrons arriving at your instrument to measure.
anybody know how much power the Chicago pile made?
my guess in milliwatts.

 

[russ_watters]

Economics is a key part of it, and to some extent, when dealing with nuclear, so is safety.

I would say that safety is an economic issue, including an economy of scale issue: the cost of dealing with regulations does not scale proportionally to the size of a reactor/plant. I suspect this is why coal plants in the hundreds of megawatts are common, but nuclear plants are all (?) in the thousands of megawatts.

 

[Astronuc]

I would say that safety is an economic issue, including an economy of scale issue: the cost of dealing with regulations does not scale proportionally to the size of a reactor/plant. I suspect this is why coal plants in the hundreds of megawatts are common, but nuclear plants are all (?) in the thousands of megawatts.

The cost of safety is certainly an economic issue, and most of that is probably in the upfront capital cost - the cost of the structures and safety system with some redundancy.

In the US, there are NP plants in the 500-800 MWe range, 800-1000 MWe, and > 1000 MWe.

35 of 69 PWRs in the US have net electrical capacity > 1000 MWe.

R.E.Ginna          498 MWe
Fort Calhoun       500 MWe
Point Beach 1      512 MWe
Point Beach 2      514 MWe
Prairie Island 2   545 MWe
Prairie Island 1   551 MWe
Kewaunee           556 MWe
H.B.Robinson       710 MWe
Turkey Point 4     720 MWe
Turkey Point 3     720 MWe
Palisades          778 MWe
Three Mile Isl. 1  786 MWe
Surry 1            799 MWe
Surry 2            799 MWe
Crystal River 3    838 MWe
St. Lucie 2        839 MWe
St. Lucie 1        839 MWe
ANO 1              843 MWe
Oconee 1           846 MWe
Oconee 2           846 MWe
Oconee 3           846 MWe
Beaver Valley 2    846 MWe
J.Farley 1         851 MWe
J.Farley 2         860 MWe
Calvert Cliffs 2   862 MWe
Calvert Cliffs 1   873 MWe
Millstone 2        884 MWe
Beaver Valley 1    892 MWe
Shearon Harris     900 MWe
Davis Besse        913 MWe
V.C. Summer        966 MWe
North Anna 2       972.9 MWe
North Anna 1       980.5 MWe
ANO 2              995 MWe

D.C.Cook 1        1009 MWe
Indian Point 2    1020 MWe
Indian Point 3    1025 MWe
D.C.Cook 2        1060 MWe
San Onofre 2      1070 MWe
San Onofre 3      1080 MWe
McGuire 1         1100 MWe
McGuire 2         1100 MWe
A.Vogtle 1        1109 MWe
Watts Bar 1       1123 MWe
Sequoyah 2        1126 MWe
A.Vogtle 2        1127 MWe
Catawba 2         1129 MWe
Catawba 1         1129 MWe
Salem 2           1130 MWe
Byron 2           1136 MWe
Sequoyah 1        1148 MWe
Diablo Canyon 2   1149 MWe
Comanche Peak 2   1150 MWe
Diablo Canyon 1   1151 MWe
Braidwood 2       1152 MWe
Byron 1           1164 MWe
Wolf Creek1       1166 MWe
Salem 1           1174 MWe
Braidwood 1       1178 MWe
Comanche Peak 1   1200 MWe
Millstone 3       1227 MWe
Callaway          1236 MWe
Waterford         1250 MWe
Seabrook 1        1295 MWe
Palo Verde 3      1335 MWe
Palo Verde 2      1335 MWe
Palo Verde 1      1335 MWe
South Texas 2     1410 MWe
South Texas 1     1410 MWe

18 of 35 BWRs in the US have net electrical capacity > 1000 MWe.

Vermont Yankee     510 MWe
Monticello         579 MWe
Oyster Creek       619 MWe
Nine Mile Point 1  621 MWe
Duane Arnold       640 MWe
Pilgrim            685 MWe
Cooper             830 MWe
J.A.Fitzpatrick    852 MWe
Dresden 3          867 MWe
Dresden 2          867 MWe
Quad Cities 1      867 MWe
Quad Cities 2      869 MWe
E.I.Hatch 1        876 MWe
E.I.Hatch 2        883 MWe
Brunswick 2        937 MWe
Brunswick 1        938 MWe
River Bend 1       989 MWe

Hope Creek 1      1061 MWe
Browns Ferry 1    1065 MWe
Clinton           1065 MWe
Browns Ferry 2    1104 MWe
Peach Bottom 2    1112 MWe
Peach Bottom 3    1112 MWe
Browns Ferry 3    1115 MWe
LaSalle 1         1118 MWe
LaSalle 2         1120 MWe
Fermi 2           1122 MWe
Limerick 2        1134 MWe
Limerick 1        1134 MWe
Susquehanna 2     1140 MWe
Nine Mile Point 2 1140 MWe
Susquehanna 1     1149 MWe
Columbia Gen Sta  1190 MWe
Perry 1           1261 MWe
Grand Gulf        1297 MWe

Source: US NRC

 

[average guy]

astro nuke
i'll be with the living here in a moment.
jim
how about an 'Atomic Powered Bomber' ?
http://en.wikipedia.org/wiki/Nuclear_aircraft
same idea as 'no diesel needed'.

Have A Nice Day!

 

[jim hardy]

""jim
how about an 'Atomic Powered Bomber' ?""

now THAT was a crazy idea...
i saw a photo of it in the bomb bay of a B36 -
had they ever run it it'd probably have killed the crew
and been unapproachable on the ground.

if you find such history interesting you'd like Freeman Dyson's book "Disturbig the Universe"
He was a Manhattan Project physicist who worked on experimental reactors of the fifties, including the rocket engine.
He's still actively writing about science, must be in his nineties now,

and remains as refreshingly logical and insightful as ever.

http://www.nybooks.com/articles/archives/2011/dec/22/how-dispel-your-illusions/?pagination=false

 

[etudiant]

""jim
how about an 'Atomic Powered Bomber' ?""

now THAT was a crazy idea...
i saw a photo of it in the bomb bay of a B36 -
had they ever run it it'd probably have killed the crew
and been unapproachable on the ground.

if you find such history interesting you'd like Freeman Dyson's book "Disturbig the Universe"
He was a Manhattan Project physicist who worked on experimental reactors of the fifties, including the rocket engine.
He's still actively writing about science, must be in his nineties now,

and remains as refreshingly logical and insightful as ever.

http://www.nybooks.com/articles/archives/2011/dec/22/how-dispel-your-illusions/?pagination=false

Afaik, the B36 was only the carrier aircraft for a reactor mockup, not for a real one.
The idea was to test the ancillary gear in a flight configuration. The actual nuclear powered aircraft would have been materially bigger.
Oddly enough, the idea died primarily because the nuclear propulsion was not easily applied to supersonic flight, the USAF priority at the time. I believe the nuclear reactor was a classic steam generator, rather than something that heated air directly. A later concept did involve direct core heating of the air for propulsion in a mach 3 low altitude ramjet, but this would have been an unmanned vehicle, an early cruise missile.

Apart from the aircraft speculation, it still seems to me that a small reactor for supporting remote sites would be a very good idea. The fuel convoys across Antarctica drecking up the worlds cleanest landscape are an ongoing scandal, imho, when a small reactor could supply all the heat and light needed. Could a standard Navy reactor not be used instead or is the lack of liquid cooling water a deal killer?

 

[jim hardy]

you know more about it than i do.

i had an older friend who'd worked on airp;ane reactor, said it heated air for the turbojets but didnt say whether direct or via intermediate heat transport medium like water.

AFAIK the Army plant in Antarctica was a scaled down Navy style plant.
no reason it couldn't reject steam cycle heat to an air cooled condenser
and distill its own water needs. if you parked it adjacent a lake it could cool itself from that.

""Afaik, the B36 was only the carrier aircraft for a reactor mockup, not for a real one.
The idea was to test the ancillary gear in a flight configuration. The actual nuclear powered aircraft would have been materially bigger.""

Bigger than a B36?? Now that's something. My earliest memory is from ca 1948 - i was about two, living not far from OpaLocka Airfield near Miami.. We kids heard this terrifying roar and shriek and a HUGE airplane flew over at treetop level, the wings seemed horizon to horizon and had their propellers on wrong side. We all high-tailed it for the bushes. Still a vivid memory after 63 years.

 

[etudiant]

you know more about it than i do.

i had an older friend who'd worked on airp;ane reactor, said it heated air for the turbojets but didnt say whether direct or via intermediate heat transport medium like water.

AFAIK the Army plant in Antarctica was a scaled down Navy style plant.
no reason it couldn't reject steam cycle heat to an air cooled condenser
and distill its own water needs. if you parked it adjacent a lake it could cool itself from that.

Bigger than a B36?? Now that's something. My earliest memory is from ca 1948 - i was about two, living not far from OpaLocka Airfield near Miami.. We kids heard this terrifying roar and shriek and a HUGE airplane flew over at treetop level, the wings seemed horizon to horizon and had their propellers on wrong side. We all high-tailed it for the bushes. Still a vivid memory after 63 years.

The waste heat issue should not be a problem in a place such as Antarctica, simply because even the residual hot water would be a desirable resource. The heat exchanger would need to be specified with some care though, because it would need to function equally well at 50 below in a 100 mph wind as on a quiet sunny above freezing day. Lakes are a temperate zone luxury, unfortunately not found in Antarctica.

The projected atomic plane would have been at least twice the gross weight of a B-36. My guess is a 30+% increase in wingspan, perhaps someone who knows could add detail.
I'm surprised by the input about using the reactor heat for the engines directly.
The problem with using heat directly from the core is that a jet engine performance is constrained by the materials, which have to withstand the heat produced by compression of the incoming air. Superheating that air with a reactor rather than feeding it through the combustors would really be wonderful, but currently requires unobtainium to be workable.
Did they find a deposit of it back in the 1950s? Or maybe Powerpoint engineering has a longer history than we appreciate.