User:FuzzyMagma/TRISO particle fuel

TRISO

https://escholarship.org/content/qt6v84b2c6/qt6v84b2c6_noSplash_e98abae7627b314acab21260661c66ca.pdf

https://www.nrc.gov/docs/ML2117/ML21175A152.pdf

https://pure.manchester.ac.uk/ws/portalfiles/portal/54559108/FULL_TEXT.PDF

https://pure.manchester.ac.uk/ws/portalfiles/portal/54524750/FULL_TEXT.PDF

https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=2453&context=etd

https://web.mit.edu/pebble-bed/papers1_files/Thesis%20on%20MIT%20Fuel%20Code%20Benchmarking.pdf

http://www.janleenkloosterman.nl/reports/thesis_roubiou_2022.pdf

https://www-pub.iaea.org/MTCD/publications/PDF/TE-1761_web.pdf

https://art.inl.gov/Meetings/GCR_Program_Review_07-13-21/Presentations/Session%201/5%20Gerczak%20-%20SEM%20Analysis.pdf Tristructural-isotropic (TRISO) fuel particle is a type of micro-particle fuel. A particle consists of a kernel of UOX fuel (sometimes UC or UCO), which has been coated with four layers of three isotropic materials deposited through fluidized chemical vapor deposition (FCVD). The four layers are a porous buffer layer made of carbon that absorbs fission product recoils, followed by a dense inner layer of protective pyrolytic carbon (PyC), followed by a ceramic layer of SiC to retain fission products at elevated temperatures and to give the TRISO particle more structural integrity, followed by a dense outer layer of PyC. TRISO particles are then encapsulated into cylindrical or spherical graphite pellets. TRISO fuel particles are designed not to crack due to the stresses from processes (such as differential thermal expansion or fission gas pressure) at temperatures up to 1600 °C, and therefore can contain the fuel in the worst of accident scenarios in a properly designed reactor. Two such reactor designs are the prismatic-block gas-cooled reactor (such as the GT-MHR) and the pebble-bed reactor (PBR). Both of these reactor designs are high temperature gas reactors (HTGRs). These are also the basic reactor designs of very-high-temperature reactors (VHTRs), one of the six classes of reactor designs in the Generation IV initiative that is attempting to reach even higher HTGR outlet temperatures. TRISO fuel particles were originally developed in the United Kingdom as part of the Dragon reactor project. The inclusion of the SiC as diffusion barrier was first suggested by D. T. Livey. The first nuclear reactor to use TRISO fuels was the Dragon reactor and the first powerplant was the THTR-300. Currently, TRISO fuel compacts are being used in some experimental reactors, such as the HTR-10 in China and the high-temperature engineering test reactor in Japan. Spherical fuel elements utilizing a TRISO particle with a UO2 and UC solid solution kernel are being used in the Xe-100 in the United States.

TRISO (from English TRistructural-ISOtropic ) is a form of nuclear fuel processing that consists of triple-jacketed pac-beads. In the center is a core of uranium(IV) oxide, or a uranium/ thorium mixed oxide , which is followed by a porous buffer layer with an inner layer of isotropic pyrographite , then a layer of high strength silicon carbide and finally an outer layer coated with isotropic pyrographite. The core of the German variant has a diameter of 0.5 mm, the entire particle is 0.91 mm in size.

The additional, innermost carbon layer is porous and provides expansion volume for the absorption of fission products; the two pyrographite layers ensure gas tightness.

TRISO was developed around 1970 in Great Britain for the Dragon high-temperature reactor ( 1967-1975), the inventor is considered to be DT Livey. In Germany it was used in the AVR (Jülich) from 1981, but not in the THTR-300. The TRISO particles are clearly superior to the older, double-coated BISO particles with regard to particle breakage caused by radiation. On the other hand, the effect of TRISO silicon carbide as a diffusion barrier for some nuclides such as cesium-137 and silver-110m at higher temperatures is unsatisfactory - even in comparison with BISO particles. Therefore, only maximum working temperatures of 750 °C are currently envisaged for high-temperature reactors with TRISO fuel, and the planned application of TRISO fuel for high-temperature process heat generation (950-1000 °C) has been postponed.

Further development is currently only taking place in the USA. In tests there, a short-term temperature resistance of the coatings of 1800 °C was achieved.


 * Preliminary three-dimensional neutronic analysis of IFBA coated TRISO fuel particles in prismatic-core advanced high temperature reactor https://doi.org/10.1016/j.anucene.2021.108551
 * Preliminary Study of a Prismatic-Core Advanced High-Temperature Reactor Fuel Using Homogenization Double-Heterogeneous Method https://doi.org/10.1080/00295639.2019.1672511
 * TRISO fuel descripción
 * Non-Destructive Examination of SiC Nuclear Fuel Shell using X-Ray Fluorescence Microtomography Technique
 * GT-MHR fuel compact process
 * Description of TRISO fuel for "pebbles"
 * LANL webpage showing various stages of TRISO fuel production
 * Method to calculate the temperature profile in TRISO fuel

The fuel used in HTGRs is coated fuel particles, such as TRISO   fuel particles. Coated fuel particles have fuel kernels, usually made of uranium dioxide, however, uranium carbide or uranium oxycarbide are also possibilities. Uranium oxycarbide combines uranium carbide with the uranium dioxide to reduce the oxygen stoichiometry. Less oxygen may lower the internal pressure in the TRISO particles caused by the formation of carbon monoxide, due to the oxidization of the porous carbon layer in the particle. The TRISO particles are either dispersed in a pebble for the pebble bed design or molded into compacts/rods that are then inserted into the hexagonal graphite blocks. The QUADRISO fuel concept conceived at Argonne National Laboratory has been used to better manage the excess of reactivity.

The basic design of pebble-bed reactors features spherical fuel elements called pebbles. These tennis ball-sized pebbles (approx. 6.7 cm in diameter) are made of pyrolytic graphite (which acts as the moderator), and they contain thousands of micro-fuel particles called tristructural-isotropic (TRISO) particles. These TRISO fuel particles consist of a fissile material (such as 235U) surrounded by a ceramic layer coating of silicon carbide for structural integrity and fission product containment. In the PBR, thousands of pebbles are amassed to create a reactor core, and are cooled by a gas, such as helium, nitrogen or carbon dioxide, that does not react chemically with the fuel elements. Other coolants such as FLiBe (molten fluoride, lithium, beryllium salt) ) have also been suggested for implementation with pebble fuelled reactors. Some examples of this type of reactor are claimed to be passively safe.

QUADRISO fuel
In QUADRISO particles a burnable neutron poison (europium oxide or erbium oxide or carbide) layer surrounds the fuel kernel of ordinary TRISO particles to better manage the excess of reactivity. If the core is equipped both with TRISO and QUADRISO fuels, at beginning of life neutrons do not reach the fuel of the QUADRISO particles because they are stopped by the burnable poison. During reactor operation, neutron irradiation of the poison causes it to "burn up" or progressively transmute to non-poison isotopes, depleting this poison effect and leaving progressively more neutrons available for sustaining the chain-reaction. This mechanism compensates for the accumulation of undesirable neutron poisons which are an unavoidable part of the fission products, as well as normal fissile fuel "burn up" or depletion. In the generalized QUADRISO fuel concept the poison can eventually be mixed with the fuel kernel or the outer pyrocarbon. The QUADRISO concept was conceived at Argonne National Laboratory.

Companies
U-Battery

Centrus Energy

THTR-300

HT3R

Pebble Bed Modular Reactor (PBMR): South Africa

Pebble Bed Modular Reactor (PBMR): South Africa
The Pebble Bed Modular Reactor (PBMR) is a modernized version of a design first proposed in the 1950s and deployed in the 1960s in Germany. It uses spherical fuel elements coated with graphite and silicon carbide filled with up to 10,000 TRISO particles, which contain uranium dioxide and appropriate passivation and safety layers. The pebbles are then placed into a reactor core, comprising around 450,000 "pebbles". The core's output is 165MWe. It runs at very high temperatures (900°C) and uses helium, a noble gas as the primary coolant; helium is used as it does not interact with structural or nuclear materials. Heat can be transferred to steam generators or gas turbines, which can use either Rankine (steam) or Brayton (gas turbine) cycles. South Africa terminated funding for the development of the PBMR in 2010 and postponed the project indefinitely ); most engineers and scientists working on the project have moved abroad to nations such as the United States, Australia, and Canada.

Fluoride salt-cooled high-temperature reactor
The fluoride salt-cooled high-temperature reactor (FHR), also called advanced high temperature reactor (AHTR), is also a proposed Generation IV molten salt reactor variant regarded promising for the long-term future. The FHR/AHTR reactor uses a solid-fuel system along with a molten fluoride salt as coolant.

One version of the Very-high-temperature reactor (VHTR) under study was the liquid-salt very-high-temperature reactor (LS-VHTR). It uses liquid salt as a coolant in the primary loop, rather than a single helium loop. It relies on "TRISO" fuel dispersed in graphite. Early AHTR research focused on graphite in the form of graphite rods that would be inserted in hexagonal moderating graphite blocks, but current studies focus primarily on pebble-type fuel. The LS-VHTR can work at very high temperatures (the boiling point of most molten salt candidates is >1400 °C); low-pressure cooling that can be used to match hydrogen production facility conditions (most thermochemical cycles require temperatures in excess of 750 °C); better electric conversion efficiency than a helium-cooled VHTR operating in similar conditions; passive safety systems and better retention of fission products in the event of an accident.

In 2021, Tennessee Valley Authority (TVA) and Kairos Power announced a TRISO-fueled, fluoride salt-cooled 50MWt test reactor would be deployed at Oak Ridge, Tennessee. Also in 2021, Southern Company, in collaboration with TerraPower and the U.S. Department of Energy announced plans to build the Molten Chloride Reactor Experiment, the first fast-spectrum salt reactor at the Idaho National Laboratory.

Heat pipe reactor design is the simplest microreactor, which improves power transfer and avoids the use of pumps to circulate the coolant. Microreactors based on HTGR technology use a three-structure isotropic (TRISO) fuel, the same as that used in larger HTGR designs. For FR technologies that provide compactness and energy efficiency, proven oxide fuels, more experimental metals or nitride fuels are available. The experimental fuel is expected to be more efficient for microreactors, as the residence time of the fuel in the reactor core is much longer than in conventional reactors, leading to higher radiation exposure.

In December 2022, BWXT started the TRISO fuel production at BWX Technologies Inc's Lynchburg facility in Virginia.

It will use TRISO fuel (2022)—Idaho National Laboratory will assemble a Project Pele transportable nuclear reactor, and test it for up to three years; if test performance warrants it, this type of reactor will generate a nominal 2 MWe (1 to 5 MWe— megaWatts, electrical) for up to 3 years, for isolated areas such as the Arctic, or for an island; the reactor will be gas-cooled;   the fuel will be high-assay low-enriched uranium (HALEU); experiments for handling the nuclear fuel will be performed at Idaho National Labs Transient Reactor Test Facility (TREAT), or the Hot Fuel Examination Facility (HFEF) during the three year test period. Mobile Microreactor startup testing at the Materials and Fuels Complex (MFC), or at the Critical Infrastructure Test Range Complex (CITRC). Assembling, operating, and disassembling, and transporting the Mobile Microreactor at the MFC, or at the CITRC. Transporting the disassembled mobile microreactor to temporary storage at the Radioactive Scrap and Waste Facility (RSWF), or at the Outdoor Radioactive Storage Area (ORSA). Potentially conducting mobile microreactor and spent nuclear fuel post-irradiation examination (PIE) and disposition at Idaho National Lab. Produce reliable electrical power on an electrical grid that is separate from the public utility grid at Idaho National Lab.

The Gas Turbine Modular Helium Reactor (GT-MHR) is a class of nuclear fission power reactor designed that was under development by a group of Russian enterprises (OKBM Afrikantov, Kurchatov Institute, VNIINM and others), an American group headed by General Atomics, French Framatome and Japanese Fuji Electric. It is a helium cooled, graphite moderated reactor and uses TRISO fuel compacts in a prismatic core design. The power is generated via a gas turbine rather than via the more common steam turbine.

X-energy claims that TRISO fuel will make nuclear meltdowns virtually impossible.

AVR reactor