Introduction: If push comes to shove
Fermi I - A Molten Sodium Cooled Fast Breeder Reactor
A
Good Introduction To Molten Salt Reactors From Wikipedia
Part One:
TRISO molten salt cooled very high temperature reactor
Part Two:
Liquid Fluoride Thorium Reactor - the LFTR (The author is still
trying to sort this one out.)
Part Three:
Part Four:
IFR - The Integral Fast Reactor. A molten metal reactor.
Liquid Reactors, Introduction:
If push comes to shove
Global Warming is a real emergency. A conversion demonstration facility project might emerge far sooner rather than expected. What I, as an application engineer, must do: Go with what I find in the catalogs. The other sufficiently hot reactor types shown on other pages - TRISO Pebble Beds, TRISO Prisms, and TRIGA-like Hyperion - discussed on this web site are being offered commercially. So far, the liquid cooled reactors have not been considered ready for 'prime time'.
Liquid cooled reactors, on paper, appear to have both the temperature and sufficient BTU output to be considered as possible candidates for Coal Yard Nuke and Hybrid Nuke applications but have never been used in any commercial application. As an application engineer, I can't specify anything for immediate use that isn't in a vendor's catalog. In some ways, these reactors look like the most promising of the bunch, and at 800°C, 1,500°F, are plenty hot enough to produce the supercritical water needed to drive a 1,000°F superheated steam generator. The jury's is still out on these reactors and I personally hope very much they get a "Two Thumbs Up" when the jury returns.
Why use high temperature - instead of conventional - nuclear reactors to replace coal?
A 550°F conventional nuclear reactor can't power a 1,000°F coal plant . . . It simply isn't hot enough. Coal can produce heat over 2,000°F. Coal power plants use 1,000°F steam for high efficiency. Conventional nuclear reactors cannot produce steam hotter than 550°F, so conventional nuclear reactors cannot be used to produce coal's 1,000°F steam. High-temperature reactors will work just fine.
Why stay with steam?
Water is a wonderful way to turn heat energy into mechanical energy
because when you turn water into steam it changes state, expanding its volume
1,600 times. If the steam is not allowed to expand freely in volume, its
pressure will go up drastically. That's where all that piston-pushing
power in a steam locomotive comes from. If the steam is turned back into
water by cooling it changes state again, this time contracting in volume 1,600 times, creating a powerful vacuum.
Both the Coal Yard Nuke and the Hybrid Nuke are "State of the Market", not "State of the Art", applications where economics plays the pivotal role.
Why use a liquid coolant in a reactor?
A cubic foot of water will carry about 3,000 times as much heat as a cubic foot of air. Gas cooled reactors are odd man out in the reactor world.
Fermi 1 - A Solid Metal Fuel Rod, Molten Sodium Cooled, Fast Breeder Reactor
As an electrical engineering
student, the author worked as a designer in 1959 on the molten
sodium Fermi I reactor being built at Monroe, Michigan, drawing
wiring diagrams for instrumentation systems such multi-point
http://en.wikipedia.org/wiki/Enrico_Fermi_Nuclear_Generating_Station About Fermi 1
http://en.wikipedia.org/wiki/Sodium-cooled_fast_reactor Son of Fermi 1?
http://en.wikipedia.org/wiki/Integral_Fast_Reactor GE-Hitachi ARC - Advanced Reactor Designs.pdf GE-Hitachi Advanced Recycling Center.pdf
A Good Introduction To Molten Salt Reactors From Wikipedia:
http://en.wikipedia.org/wiki/Molten_salt_reactor Wikipedia's page on Molten Salt Reactors
"Research is currently picking up again for reactors that utilize molten salts for coolant. Both the traditional molten salt reactor and the Very High Temperature Reactor (VHTR) have been picked as potential designs to be studied under the Generation Four Initiative (GEN-IV).
A version of the VHTR currently being studied is the Liquid Salt Very High Temperature Reactor (LS-VHTR). It is essentially a standard VHTR design that uses liquid salt as a coolant in the primary loop, rather than a single helium loop. It relies on "TRISO" fuel dispersed in graphite. The fuel graphite would be in the form of graphite rods that would be inserted in hexagonal moderating graphite blocks. The molten salt would pass through holes drilled in the graphite blocks.
The LS-VHTR has many
attractive features, including: the ability to work at very high
temperatures (the boiling point of most molten salts being
considered are >1400 °C, 2,600
Liquid Fluoride-Thorium Reactor
![[thm.jpg]](http://1.bp.blogspot.com/_-1USRv70-rY/SClzQvabLMI/AAAAAAAAAAM/mkD0coPMD-o/S220/thm.jpg)
In many designs the nuclear fuel
is dissolved in the molten fluoride salt coolant as uranium tetrafluoride (UF4).
The fluid becomes critical in a graphite core which serves as the moderator. --
Wikipedia
(Right)
MSR Liquid Reactors Molten-Salt-Reactor Technology Gaps .pdf by Charles W. Forsberg, ORNL, (2006), is a good introductory paper addressing modern thinking about LFTR/MSRs.
MSR = Molten Salt Reactors . . . LFR = Liquid Fluoride Reactors . . . LFTR = Liquid Fluoride - Thorium Reactor
In Coal Yard Nuke service, the secondary (or possibly tertiary) cooling loop could be a gas such as helium or nitrogen and would drive a liquid-lead pressure isolating dual-tube calandria supercritical water heater in much the same manner as the 1,700°F pebble bed reactor. Perhaps multiple heaters in the spirit of THTR-300 or IRIS for increased reliability. Pressures would probably be similar and efficiency would nothing to brag about. But, as with the pebble bed, emissions, not efficiency, would be the name of the game here and no one doubts the ability of a LFTR to make the supercritically hot water needed to simultaneously drive a variety of old superheated and non-superheated steam turbines.
If
the reactor could be located close enough to, and dedicated to, a single
turbine, a Hybrid nuclear reactor, coal turbine, power plant using a
A good place to go to find a lot of papers on the LFTR: http://www.energyfromthorium.com/pdf/
A thorium energy metal company:
http://thoriumenergy.com/
Websnags:
"The molten salt reactor is a
nice design. As I understand it; one of the major drawbacks is that the
reactor operator [ the electric utility company that would employ such a reactor
] would have to operate the molten salt reactor's chemical processing facility.
That is; a facility to continually reprocess the reactor's molten fuel is an
integral part of the operation of such a reactor.
Thus the operation of a molten salt reactor is more complex than even operating
a commercial light water reactor. This was more complexity than most electric
utility companies at the time wanted to undertake - they were in the business of
generating power, not operating a chemical processing plant.
The IFR concept also includes an on-site reprocessing facility - but a facility
based on electrorefining would be simpler to operate than a chemical processing
plant.
For both concepts; it is a matter of how much complexity the reactor owner wants
to manage."
Dr. Gregory Greenman
Physicist
[Note: The circulating core material that is being processed is both very thermally hot and also very radioactive. On the plus side, the liquid does not need to be pressurized. -- JH]
Δ
"Here at Ohio State University, my
class in nuclear design (a team based approach) investigated the LFR. It is a
research based class, and each year, the class builds upon the previous year's
work. It was started (I believe) here at OSU in 2004 or 2005).
The reactor does indeed use a FLiBe salt using thorium, with a blanket
surrounding it as a breeder material. There were some promising results, but
yes, the online processing turned out to be one of the major challenges, as well
as initial startup. It required a substantial amount of U-233 to start, but
eventually enough U-233 was bred so that it could supply startup uranium for
additional reactors. I went through the class Fall 2007, so I don't know what
advances (if any) were made this past quarter."
Mega-Nukes
The author thinks that, for Global Warming mitigation retrofit service, LFTRs are best suited to power the world's 5,000 biggest CO2 offenders. One to six pairs of 1 GWt each would drive a pair of supercritical water trunk lines to as many as 10 steam generators, replacing 10 coal burning boilers. The size of the system would help justify the additional burden of their radioactive core/coolant cleaning facilities.
Cleaning up the world's 5,000 biggest coal burning power plants would push the tipping point back several decades.
Bob Hargraves' "Aim High" LFTR presentation.
You need to watch the entire "Video" (slide + audio)
presentation at:
he also suggests:
Also, a really good 1 hour video on liquid reactors:
(Images below are a few screenshots from from Bob Hargraves' "Aim High" presentation.)
The Integral Fast Reactor
