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Gigaton - some Big Energy ideas
Why wasn’t fusion considered? It will be available in far less then ten years. Do some research?
The concept of fusion-fission hybrids – using high-energy neutrons from fusion reactions to transmute, or burn, fissile material – has been explored by Andrei Sakharov, Hans Bethe and other scientists since about 1951. Although the focus of many of these studies was the use of fusion neutrons to generate fuel for fast nuclear reactors, Nikolai Basov and others discussed the possibility of fast neutrons to drive a fission blanket for generating power. Many proposals have also been made to use accelerators to generate neutrons that can then be used to burn nuclear waste and generate electricity.
Fusion-fission engines did not advance beyond the discussion stage at that time because powerful high energy neutron sources and other required technologies did not exist. Similarly, accelerator-based schemes never advanced past the conceptual study phase, in part because a complete nuclear fuel cycle – including uranium enrichment and nuclear waste reprocessing – was still required to generate economical electricity. The inefficiency and cost of those systems outweighed the benefit of transmuting nuclear waste.
Today, however, researchers have demonstrated the physics and key technologies required to make fusion/fission hybrid a reality. The capability of Field Reversed Configuration (
) to create the conditions required for ignition and thermonuclear burn in the laboratory with inertial confinement fusion (
) has been demonstrated by the 1/3 scale model of the Helion Energy prototype.
The FRC Power Plant
The FRC is designed to operate with fusion energy gains of about 6 and fusion yields of about 20 MJ to provide about 100 to 200 megawatts (
) of fusion/fission power – about 80 percent of which comes in the form of 14.1 million electron-volt (MeV) neutrons with the rest of the energy in X-rays and ions.
The fission blanket contains 40 metric tons (
) thorium (Th232);
The point source of fusion neutrons acts as a catalyst to drive the fission blanket, so there is no need for a critical assembly to sustain the fission chain reaction. Starting from as little 20 MW of fusion power, a single FRC engine can generate 100 to 200 megawatts in steady state for periods of years to decades.
The fission Blanket
The blanket is comprised of a molten salt called flibe (2LiF + BeF2 ) and thorium fluoride. It carries away heat and also produces tritium that can be harvested to manufacture new deuterium-tritium fusion plasma packets.
The Burn Chamber
The neutrons pass through the first beryllium wall which surrounds the point of T – D fusion. This wall generates 1.8 neutrons for every neutron that it absorbs. The newly generated neutrons have a significantly lower energy spectrum that is ideal for fission energy generation in the thorium blanket. To keep the first wall cool, the molten salt is allowed to form a constantly flowing cover on the inside of the first wall where a coating of imbedded carbon nano-fibers increase the service area and the thickness of this liquid first wall.
The moderated neutrons strike the next layer, a two-meter-thick, subcritical fission blanket containing 40 MT of thorium fuel. The neutrons absorbed by the blanket drive neutron capture and fission reactions, releasing tremendous amounts of heat to drive turbines.
The burn chamber is oriented vertically, and the molten fluoride salt is pumped from top to bottom within the chamber. Both a blanket of high pressure helium and an axial magnetic field keeps the molten salt away from the second wall and at the same time cools its surface and the pulsed magnets on the outside of the burn chamber.
The flow of helium gas removes both tritium produced during fission of lithium 6 in the filBe and gaseous fission products.
Heat is removed from the molten salt by the primary heat exchangers.
A fission/fusion hybrid is the only way to go. The fusion energy gain Qfus can be less then one and still produce copious amounts of heat from the fission blanket.
The production of ion heating from fusion alone hardly matters Almost all of the power of the FRC reactor is produced as heat from the fission reaction.
Even if fusion breakeven is not achieved; more power is produced by fission in the blanket that is formed in a perfectly efficient fusion reactor.
Because of the continuous availability of external neutrons from the fusion source, a FRC engine can extract more than 99.8 percent of the energy content of its fuel, resulting in greatly enhanced energy generation per metric ton of nuclear fuel. The external source of neutrons also allows the FRC engine to burn the initial fertile or fissile fuel to more than 99 percent FIMA (fission of initial metal atoms) without refueling or reprocessing, allowing for nuclear waste forms with significantly reduced concentrations of long-lived, weapons-usable actinides per gigawatt-year of electric energy produced. This remaining waste has such a low actinide content that it falls into DOE's lowest attractiveness category for nuclear proliferation.
In addition, because of the very high fission product content, the waste is self-protecting for decades: its radiation flux is so great that any attempt at stealing it would be suicidal.
Following the initial interim storage and cooling at the reactor site, a geological repository similar to Yucca Mountain could be used for long-term storage or disposal. The size of a geological repository needed to accommodate a entire fleet of FRC engines (with the same generating capacity as our current Light water reactor (
) fleet with a once-through fuel cycle) will be approximately 5 percent of that required for disposal of LWR nuclear waste in a geological repository similar to Yucca Mountain.
Jun 27 02:07 AM
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Nuclear Power: Going Fast
By imposing an ever increasing price on a ton of CO2 emissions, a carbon tax (aka - cap and trade) will force utilities to convert CO2 producing power plants to non CO2 producing ones.
This clear market signal for clean power production may be blunted by conflicting business as usual policies currently in place at the NRC.
I predict that both the existing reactor builders as well as some new industry entrants encouraged by the possibilities implied in this powerful market signal will introduce air cooled intermediate sized reactors. This market signal will also strongly motivate the utilities to convert existing coal plants to nuclear. What may stop this trend is the conflicting custom built big reactor culture that has firmly entrenched itself deeply in the nuclear power business.
In order for cap and trade to avoid being distorted so that it may do its job effectively, the government must be wise enough to restructure the NRC to ease the way for the commercialization of the intermediate sized reactor market. This future market need for clean base load power will almost certainly be there and if not properly met will lead to confusion, disillusionment, and recrimination that has typified nuclear power for so long.
Jun 23 03:35 PM
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Forget Biofuels, Future Energy Architecture Will Have Solar at Its Core
The time is right to support a new nuclear technology in America.
In his open letter to the President Obama, the climatologist Dr. Jim Hanson recommended the Thorium fuel cycle and the Liquid Fluoride Thorium Reactor (
). Dr. Edward Teller, the father of Fusion, after a lifetime of work on every aspect of nuclear technology had at the end of his life come to this conclusion in his final study: the LFTR is the best of all possible reactor types.
The LFTR, which is currently in development in France, Japan, and Russia, is a little known but very simple, efficient, and elegant type of reactor which allows for base load, load following, or peak power production. It can start up on any kind of nuclear fuel, bomb material, or nuclear waste product to produce very efficient, high temperature heat and at the same time breed more fuel in the bargain. This thrifty approach to nuclear energy greatly appeals to me, but I became even more interested in the LFTR when the details of a new patent were revealed by Dr LeBlanc (see below @ minute 53). It opens up the possibility of building a very compact but powerful reactor that can run for 30 years without refueling. With no danger of a core meltdown or runaway reaction, it can be operated remotely in an unattended fully automated intrusion detecting mode and sited underground while it breeds self perpetuating new fuel within the thorium structure of the reactor itself.
In order to get to its fuel, U233 that has been produced inside the very solid metal walls of this 200 ton reactor containment vessel, a proliferator must destroy and disassemble the reactor, lift its heavy reactor core out of a 100 meter deep reinforced aircraft crash proof hole in the ground, then cut the thorium containment vessel up into small pieces while enduring heavy killing gamma radiation exposure, next reprocess these reactor pieces using isotopic separation since the U233 is denatured with enough U238 to make chemical separation of bomb grade U233 impossible, and do all this without being detected. Now, this is a tall order for any proliferator and may just be an impossible assignment.
At the end of the service life of the Lftr, the reactor vessel is sent back to the factory where it is reduced to liquid fluoride salts that become the feedstock of a next new Lftr. This feedstock can only be used by the new Lftr and not for bombs. A few handfuls of waste products are held at the factory for a few hundred years to cool down before they are mined for the many precious elements contained within like platinum and iridium. Now that is what I call a safe, efficient and thrifty mode of operation!
To learn more see one of the following:
What Fusion Wanted To Be
Liquid Fluoride Reactors: A New Beginning for an Old Idea
Apr 30 04:37 PM
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