Why Technical English

Project ITER in progress

December 16, 2012
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Composed by Galina Vitkova 

The ProjectITER is a large-scale international scientific project intended to prove the practicability of nuclear fusion as an energy source. ITER was originally an acronym for the International Thermonuclear Experimental Reactor, but at present it is not considered an official abbreviation, but is connected with the Latin word “Iter” that means “way”, “journey”, “direction”.

English: deuterium-tritium fusion diagram, poi...

The project is expected to collect the data necessary for the design and operation of the first electricity-producing fusion power plant. As known all nuclear power plants (NPPs) currently operating through over the world produce electricity from fission accompanied by high-level and  long-life radioactive waste, which causes great protests of common people against these NPPs.  

The project is based on the Soviet-Russian technology tokamak (toroidal chamber with magnetic coils), which is a device using a magnetic field to confine plasma in the shape of a torus.

ITER is the culmination of decades of fusion research: more than 200 tokamaks (see also Nuclear powertokamaks) built over the world have paved the way to the ITER experiment.

Some History

Just remind the ITER Agreement was officially signed at the Elysée Palace in Paris on 21 November 2006 by Ministers from the seven ITER Members (China, theEuropean Union, India, Japan, Korea, Russia and theUnited States) in the presence of French President Jacques Chirac and the President of the European Commission José Manuel Barroso. This Agreement established a legal international entity to be responsible for construction, operation, and decommissioning of ITER. The seven ITER Members have shared in the design of the installation, the creation of the international project structure, and in its funding.

Fusion Power Grid

On 24 October 2007, after ratification by all Members, the ITER Agreement entered into force and officially constituted the ITER Organization. ITER was originally expected to cost approximately €5 billion. However, the rising price of raw materials and changes to the initial design have augmented that the amount more than triple, i.e. to €16 billion. Necessary to add that ITER members make 90% of their contribution in kind, i.e. they contribute by equipment. It means the members produce appropriate devices and fund them into the project. The remaining 10% of the contribution are paid in cash by the members. Russia undertook obligations to manufacture 18 high technology systems for the project ITER.

The program is anticipated to last for 30 years – 10 for construction, and 20 years of operation. The reactor is expected to take 10 years to build with completion in 2018 (according to some sources in 2020). The ITER site in Cadarache, France stands ready: in 2010, construction began on the ITER Tokamak and scientific buildings.

Testing

At the end of October 2012 in the Saint Petersburg Research institute of electrophysical devices named after D.V.Efremov the first tests of the unique equipment within the project ITER were launched.

Tokamak - Creating the Sun on Earth

 

The components of the diverter target prototype of the ITER reactor faced to plasma are being tested (the details about the diverter target can be found in Вольфрамовая облицовка диверторной мишени для ). A proprietary test facility IDTF (ITER Divertor Test Facility) has been built up for testing. The facility enables to expose the ITER components to the same thermal burden as during operation and  maintenance of the experimental reactor. The plasma temperature is supposed to grow up to 100 – 150  mil. degrees and expected heat loading on the diverter surface will rise up to 20 MW/m2.  That is why the components under tests shall comply with the very strict requirements.  

The components to be tested on the Russian facility have been produced in Japan. The testing is held in the presence of the ITER Agencies of Russia and Japan representants as well as with participation of the ITER International Organisation specialists.  

The conclusions about the test results are expected to be made by the end of November 2012. It will be the first of numerous series of tests and trials the results of which will enable to master well-proven technology of manufacturing the ITER components.

Diagram illustrating, in a schematic way, the ...

 

PS: The technical terms on the topic can be found in
TrainTE Vocabulary (Power engineering: English–Russian-Czech vocabulary) and in
 Vocabulary – power engineering (Russian–English–Czech).
PPS: The Russian version of the article titled Проект ИТЭР в реализации is published at the blog Technical English Remarks.

  References

 

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Fuel cycle in fusion reactors

May 25, 2011
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Composed by Galina Vitkova

Common notes

The basic concept behind any fusion reaction is to bring two or more nuclei close enough together, so that the nuclear force in nuclei will pull them together into one larger nucleus. If two light nuclei fuse, they will generally form a single nucleus with a slightly smaller mass than the sum of their original masses (though this is not always the case). The difference in mass is released as energy according to Albert Einstein’s mass-energy equivalence formula E = mc2. If the input nuclei are sufficiently massive, the resulting fusion product will be heavier than the sum of the reactants’ original masses. Due to it the reaction requires an external source of energy. The dividing line between “light” and “heavy” nuclei is iron-56. Above this atomic mass, energy will generally be released by nuclear fission reactions; below it, by fusion.

Fusion between the nuclei is opposed by their shared electrical charge, specifically the net positive charge of the protons in the nucleus. In response to it some external sources of energy must be supplied to overcome this electrostatic force. The easiest way to achieve this is to heat the atoms, which has the side effect of stripping the electrons from the atoms and leaving them as nuclei. In most experiments the nuclei and electrons are left in a fluid known as a plasma. The temperatures required to provide the nuclei with enough energy to overcome their repulsion is a function of the total charge. Thus hydrogen, which has the smallest nuclear charge, reacts at the lowest temperature. Helium has an extremely low mass per nucleon and therefore is energetically favoured as a fusion product. As a consequence, most fusion reactions combine isotopes of hydrogen (“protium“, deuterium, or tritium) to form isotopes of helium.

In both magnetic confinement and inertial confinement fusion reactor designs tritium is used as a fuel. The experimental fusion reactor ITER (see also The Project ITER – past and present) and the National Ignition Facility (NIF) will use deuterium-tritium fuel. The deuterium-tritium reaction is favorable since it has the largest fusion cross-section, which leads to the greater probability of a fusion reaction occurrence.

Deuterium-tritium (D-T) fuel cycle

D-T fusion

Deuterium-tritium (D-T) fusion

 

The easiest and most immediately promising nuclear reaction to be used for fusion power is deuterium-tritium Fuel cycle. Hydrogen-2 (Deuterium) is a naturally occurring isotope of hydrogen and as such is universally available. Hydrogen-3 (Tritium) is also an isotope of hydrogen, but it occurs naturally in only negligible amounts as a result of its radioactive half-life of 12.32 years. Consequently, the deuterium-tritium fuel cycle requires the breeding of tritium from lithium. Most reactor designs use the naturally occurring mix of lithium isotopes.

Several drawbacks are commonly attributed to the D-T fuel cycle of the fusion power:

  1. It produces substantial amounts of neutrons that result in induced radioactivity within the reactor structure.
  2. The use of D-T fusion power depends on lithium resources, which are less abundant than deuterium resources.
  3. It requires the handling of the radioisotope tritium. Similar to hydrogen, tritium is difficult to contain and may leak from reactors in certain quantity. Hence, some estimates suggest that this would represent a fairly large environmental release of radioactivity.

Problems with material design

The huge neutron flux expected in a commercial D-T fusion reactor poses problems for material design. Design of suitable materials is under way but their actual use in a reactor is not proposed until the generation later ITER (see also The Project ITER – past and present). After a single series of D-T tests at JET (Joint European Torus, the largest magnetic confinement experiment currently in operation), the vacuum vessel of the fusion reactor, which used this fuel, became sufficiently radioactive. So, remote handling needed to be used for the year following the tests.

In a production setting, the neutrons react with lithium in order to create more tritium. This deposits the energy of the neutrons in the lithium, for this reason it should be cooled to remove this energy. This reaction protects the outer portions of the reactor from the neutron flux. Newer designs, the advanced tokamak in particular, also use lithium inside the reactor core as a key element of the design.

PS: I strongly recommend to read the article FUSION(A Limitless Source Of Energy). It is a competent technical text for studying Technical English. Consequently it offers absorbing information about the topic.

 


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