Literature Reviews

Introduction

The safe, dependable, and economic process of any nation’s nuclear power reactor fleet has always been a topmost importance to countries that have the capacity to handle the use of nuclear energy. In the United States, the nuclear industry’s continual upgrading of technology, as well as advanced resources and nuclear fuels, remains vital to the industry’s achievement (Bragg-Sitton, 2014). Many decades of research joint with repetitive operations have created steady developments in technology and have also produced a wide base of information, know-how, and awareness on light-water reactor fuel performance both under normal and accident circumstances (Bragg-Sitton, 2014).

One of the exclusive undertakings of the Department of Energy’s Office of Nuclear Energy (NE) in the United States is to produce nuclear fuels and claddings with improved accident tolerance. In 2011, after the earthquake and tsunami attacks in Japan and the resultant destruction to the Fukushima Daiichi nuclear power plant complex, improving the accident tolerance of LWRs turned into a subject of serious debate (Bragg-Sitton, 2014). As such, with the directions from Congress in the United States, NE commenced accident-tolerant fuel (ATF) improvement as a key factor of the Fuel Cycle Research and Development (FCRD) Advanced Fuels Campaign (Bragg-Sitton, 2014). Before the accident at Fukushima, the importance of advanced LWR fuel progress was on developing nuclear fuel performance in terms of improved burnup for waste minimization, improved power density for power advancements, and improved fuel consistency (Bragg-Sitton, 2014).

 

 

Why use Accident-tolerant Fuel (ATF)

  • Protection
  • Dependability
  • Lower Operating Cost (Westinghouse, 2015)

Neutron properties of U3Si2

The mixed U3Si 2-Al fuel is a newly established dispersal fuel structural material used mainly in research reactors (Yong et.al, 2004). The processing technique impacts largely on the neutron and mechanical characteristics of the dispersion fuel plate, particularly, the fatigue characteristics, which are of great importance for the dependability and performance of fuel components in most reactors. The known fatigue behaviors characterized by this neutrons can be well defined by two fracture types, that is the Mode I and the mixed mode I-II (Yong et.al, 2004).

Burn Up limit

A term largely used in nuclear power technology, burnup (also identified as fuel utilization) is a degree of how much energy is taken out from a main nuclear fuel source. Burn Up is measured both as the portion of fuel atoms that went through fission in %FIMA (that is, fissions per initial metal atom) and as the real energy extracted per mass of early fuel in gigawatt-days/metric ton of thick metal or related units (ricin, 2016). To clearly understand “burnup,” it is crucial to understand more about the uranium that drives or fuels a reactor. Before fuel is made, uranium is treated to upsurge the concentration of atoms that can be divided in an organized chain response in the reactor (ricin, 2016).

So, the atoms will basically release energy as they divide. This energy generates the heat which is then turned into electricity. All together, the greater the concentration of those atoms, the lengthier the fuel can withstand a chain reaction (U.S. NRC, 2015). And the lengthier the fuel rests in the reactor, the greater the burnup. Generally, the burnup level interferes with the fuel’s temperature, physical makeup and radiation. Therefore, how hot and how radioactive used fuel is rest on burnup, along with the fuel’s initial makeup and situations in the core. All these aspects must be taken into consideration especially during the designing and approving dry storing and transport structures for used fuel (U.S. NRC, 2015).

Neutron properties of UO2

Uranium oxides, particularly UO2 have for a long time been the subject of spectroscopic examination. On the one hand, taking into account the technological significance of UO2 as a nuclear fuel, it is anticipated that spectroscopy might assist to clarify experimental outcomes of practical use (Keller, 2013). One crucial example was to come up with enough mechanisms for transport properties or characteristics or offer suitable models for the deficiency structure which is liable for nonstoichiometry. In addition, UO2 can be seen as a model compound especially uranium compounds. A number of outcomes particularly magnetic, point to a rather strong ionicity in its bond with a whole localization of the 5f shells in the U+4 ion (Keller, 2013).

Fabrication of UO2 pellets

Oxide fuel often comes in the form of cylinder-shaped pellets that measure about both in 1cm in height and diameter. This pellets are fabricated by precipitate metallurgy, extracted from enhanced uranium oxide precipitate (Parisot, 2009). Uranium enhancement is undertaken by way of the vaporous UF6 molecule. The uranium fluoride is again transformed into uranium oxide through the means of a dry transformation procedure (Parisot, 2009). The entire procedure comprises the use of an incorporated facility, including, at the head end, a hydrolysis reactor, and a rotary kiln, inside which defluorination is achieved by reductive pyrolysis, which results into the creation of uranium dioxide precipitate (Parisot, 2009).

zr neutron resistance

Zirconium is a chemical component with symbol Zr and bearing the atomic number 40. The name zirconium is formed from the mineral known as zircon, the most essential source of zirconium (Lee et.al, 2005). The term zircon generally comes from the Persian term zargun which means “gold-colored”. It is a radiant, grey-white, strong transition metal that bears the similarity of hafnium and, to a slighter extent, titanium (Lee et.al, 2005). Zirconium is regularly utilized as opacifier and a refractory even though it is used in small quantities as an alloying agent for its robust resistance to erosion (Lee et.al, 2005). Zirconium creates a selection of non-living and organometallic compounds for instance, zirconium dioxide and zirconocene dichloride, correspondingly. In this particular compound, five isotopes ensue naturally of which three are steady. Zirconium compounds have no well-known biological responsibility.

Cost of UO2 VS U3Si2

The entire cost of UO2 assembly entirely rests on the enrichment, the cost of uranium ore, transformation and enrichment, with fabrication as a smaller factor. With the anticipated ore and enrichment costs, the UO2 expenditures range from 1800 to 2000 $/kgU, or between $3.8b and $4.5b for a complete 100tPu project (Walter, 2012). Generally, the cost of U3Si2 needed for any given case is associated with weight percentages of Carbon (C) and oxygen (O) in the UC charge (Hausner, 2012). Where C’ is the weight percentage of carbon creating carbon monoxide (Hausner, 2012).

Comparison of radiation damage of fuel UO2/U3Si2 and radiation damage to SiC /Zr alloys

An important step in comprehending the effects of irradiation on UO2/U3Si2 fuels, or any material, must begin with the general nature of radiation damage on the atomic level. The atomic damage displacement ends up in a mass of defects that basically influence the fuel performance of UO2/U3Si2. On the other hand, SiC /Zr alloys compounds are regarded as attractive efficient and structural constituents for fission and fusion energy systems. The brilliant high temperature characteristics in SiC /Zr alloys, their extraordinary heat flux resistance, and importantly their radiation damage tolerance can offer intrinsic safety characteristics to the systems.

 

 

References:

Bragg-Sitton S. (2014), Overview of International Activities in Accident Tolerant Fuel Development for Light Water Reactors. Retrieved on 25th January 2016 from https://www.iaea.org/OurWork/ST/NE/NEFW/Technical-Areas/NFC/documents/TWGFPT/2014/Presentations/10-Overview_of_International_Activities_in_Accident_Tolerant_Fuel_Development_for_Light_Water_Reactors_%28Sh._Bragg-Sitton%29.pdf

Hausner H.H (2012), Modern Developments in Powder Metallurgy: Volume 3 Development and Future Prospects. Springer Science & Business Media

Keller C. (2013), Uranium: Supplement Volume C5 Uranium Dioxide, UO2, Physical Properties. Electrochemical Behavior. Springer Science & Business Media.

Lee K.L. et.al, (2005), Structure-Property Relations in Nonferrous Metals: Engineering case studies online. John Wiley & Sons

Parisot F.J. (2009), Nuclear fuels. Retrieved on 25th January 2016 from http://www.materials.cea.fr/en/PDF/MonographiesDEN/Nuclear-fuels-CEA-en.pdf

ricin (2016), About fuel burn-up rates. Retrieved on 25th January 2015 from http://www.ricin.com/nuke/bg/burnup.html

U.S. NRC (2015), Backgrounder on High Burnup Spent Fuel. Retrieved on 25th January 2015 from http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/bg-high-burnup-spent-fuel.html

Walter C.E (2012), Advanced Nuclear Systems Consuming Excess Plutonium: Volume 15 of Nato Science Partnership Subseries: 1. Springer Science & Business Media

Westinghouse (2015), Accident-tolerant Fuel Game-changing Technology for Safety, Reliability and Lower Operating Cost. Retrieved on 25th January 2016 from http://www.westinghousenuclear.com/Portals/0/Technovation%20Stuff/Accident%20Tolerant%20Fuel%20Brochure%20.pdf

Yong X. et.al, (2004), Sample records for u3si2 dispersion fuels. Retrieved on 25th January 2015 from http://www.science.gov/topicpages/u/u3si2+dispersion+fuels.html

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