Developments Related to Thorium Fusion

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Thorium

Accelerator Driven Reactors (ADS): The sub-critical ADS system is an unconventional concept that is potentially 'thorium capable'. Spallation neutrons are produced d when high-energy protons from an accelerator strike a heavy target like lead. These neutrons are directed at a region containing a thorium fuel, eg, Th-plutonium which reacts producing heat as in a conventional reactor. The system remains subcritical ie, unable to sustain a chain reaction without the proton beam. Difficulties lie with the reliability of high-energy accelerators and also with economics due to their high power consumption. (See also information page on Accelerator-Driven Nuclear Energy)

A key finding from thorium fuel studies to date is that it is not economically viable to use low-enriched uranium (LEU - with a U-235 content of up to 20%) as a fissile driver with thorium fuels, unless the fuel burn-up can be taken to very high levels - well beyond those currently attainable in LWRs with zirconium cladding.

With regard to proliferation significance, thorium-based power reactor fuels would be very poor source for fissile material usable in the illicit manufacture of an explosive device. U-233 contained in spent thorium fuel contains U-232 which decays to produce very radioactive daughter nuclides and these create a strong gamma radiation field. This confers proliferation resistance by creating significant handling problems and by greatly boosting the detectability (traceability) and ability to safeguard this material.


IPPE: Principle of Operation of Nuclear Pumped Laser

Nuclear Pumped Laser is a laser where nuclear fission fragments captured in special lasing mixture induce plasmas so that the inversion population of levels corresponds to the laser transition with appropriate wavelengths. The energy stored in the inversion population is extracted from laser cell by the optical system as a laser beam. Application of nuclear fission fragments energy for pumping of laser is a prospect and very promising way because of high energy and efficiency of particles.

Neutrons from the ignition reactor passing through the the laser active element (LAEL) are moderated and induce a chain fission reaction of uranium-235 in the coating of LAEL. The fission fragments (high energy ions) captured in lasing mixture induce plasmas with the inversion population of levels. The energy stored in the inversion population is extracted from laser module by the special optical system equipped with "feedback" and output mirrors (so-called "nuclear pumped laser generator").

Physics News Graphics: Laser-Induced Fission

In experiments conducted recently at Lawrence Livemore National Lab, an intense laser beam (from the Petawatt laser, the most powerful in the world) strikes a gold foil (backed with a layer of lead). This results in (1) the highest energy electrons (up to 100 MeV) ever to emerge from a laser-solid interaction, (2) the first laser-induced fission, and (3) the first creation of antimatter (positrons) using lasers.


Energy amplifier - Wikipedia, the free encyclopedia

The concept is credited to Carlo Rubbia, a Nobel Prize nuclear physicist and former director of Europe's CERN international nuclear physics lab. He published a proposal for a power reactor based on a proton cyclotron accelerator with a beam energy of 800 MeV to 1 GeV, and a target with thorium as fuel and lead as a coolant.

Principle and feasibility
The energy amplifier uses a synchrotron or other appropriate accelerator (e.g. cyclotron, fixed-field alternating-gradient) to produce a beam of protons. These hit a heavy metal target such as lead, thorium or uranium and produce neutrons through the process of spallation. It might be possible to increase the neutron flux through the use of a neutron amplifier, a thin film of fissile material surrounding the spallation source; the use of neutron amplification in CANDU reactors has been proposed. While CANDU is a critical design, many of the concepts can be applied to a sub-critical system.[1][2] Thorium nuclei absorb neutrons, thus breeding fissile uranium-233, an isotope of uranium which is not found in nature. Moderated neutrons produce U-233 fission, releasing energy.

This design is entirely plausible with currently available technology, but requires more study before it can be declared both practical and economical.

The concept has several potential advantages over conventional nuclear fission reactors:

Subcritical design means that the reaction could not run away - if anything went wrong, the reaction would stop and the reactor would cool down. A meltdown could however occur if the ability to cool the core was lost.
Thorium is an abundant element - much more so than uranium - reducing strategic and political supply issues and eliminating costly and energy-intensive isotope separation. There is enough thorium to generate energy for at least several thousand years at current consumption rates.[3]
The energy amplifier would produce very little plutonium, so the design is believed to be more proliferation-resistant than conventional nuclear power (although the question of uranium-233 as nuclear weapon material must be assessed carefully).
The possibility exists of using the reactor to consume plutonium, reducing the world stockpile of the very-long-lived element. Less long-lived radioactive waste is produced - the waste material would decay after 500 years to the radioactive level of coal ash. No new science is required; the technologies to build the energy amplifier have all been demonstrated. Building an energy amplifier requires only some engineering effort, not fundamental research (unlike nuclear fusion proposals).
Power generation might be economical compared to current nuclear reactor designs if the total fuel cycle and decommissioning costs are considered. The design could work on a relatively small scale, making it more suitable for countries without a well-developed power grid system
Inherent safety and safe fuel transport could make the technology more suitable for developing countries as well as in densely populated areas.

 

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Granny says, "Dey gonna blow up the world an' den it gonna pass away in fire an' flame like it says inna Bible...

'Critical phase' for Iter fusion dream
6 August 2013 > The world's largest bid to harness the power of fusion has entered a "critical" phase in southern France.

The Iter project at Cadarache in Provence is receiving the first of about one million components for its experimental reactor. Dogged by massive cost rises and long delays, building work is currently nearly two years behind schedule. The construction of the key building has even been altered to allow for the late delivery of key components. "We're not hiding anything - it's incredibly frustrating," David Campbell, a deputy director, told BBC News. "Now we're doing everything we can to recover as much time as possible. "The project is inspiring enough to give you the energy to carry on - we'd all like to see fusion energy as soon as possible."

After initial design problems and early difficulties co-ordinating this unique international project, there is now more confidence about the timetable. Since the 1950s, fusion has offered the dream of almost limitless energy - copying the fireball process that powers the Sun - fuelled by two readily available forms of hydrogen. The attraction is a combination of cheap fuel, relatively little radioactive waste and no emissions of greenhouse gases. But the technical challenges of not only handling such an extreme process but also designing ways of extracting energy from it have always been immense. In fact, fusion has long been described as so difficult to achieve that it's always been touted as being "30 years away".

The foundations for Iter's tokamak - which will contain the hot plasma - have been laid

Now the Iter reactor will put that to the test. Known as a "tokamak", it is based on the design of Jet, a European pilot project at Culham in Oxfordshire. It will involve creating a plasma of superheated gas reaching temperatures of more than 200 million C - conditions hot enough to force deuterium and tritium atoms to fuse together and release energy. The whole process will take place inside a giant magnetic field in the shape of a ring - the only way such extreme heat can be contained. The plant at JET has managed to achieve fusion reactions in very short bursts but required the use of more power than it was able to produce.

The reactor at Iter is on a much larger scale and is designed to generate 10 times more power - 500 MW - than it will consume. Iter brings together the scientific and political weight of governments representing more than half the world's population - including the European Union, which is supporting nearly half the cost of the project, together with China, India, Japan, Russia, South Korea and the United States. Contributions are mainly "in kind" rather than in cash with, for example, the EU providing all the buildings and infrastructure - which is why an exact figure for cost is not available. The rough overall budget is described as £13bn or 15bn euros. But the novel structure of Iter has itself caused friction and delays, especially in the early days.

More BBC News - 'Critical phase' for Iter fusion dream