News Column

Patent Issued for Nuclear Reactor Having Efficient and Highly Stable Thermal Transfer Fluid

June 4, 2014

By a News Reporter-Staff News Editor at Journal of Engineering -- University of Florida Research Institute Foundation, Inc. (Gainesville, FL) has been issued patent number 8731133, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Baney, Ronald H. (Gainsville, FL); Tulenko, James S. (Gainsville, FL); Powers, Kevin W. (Gainsville, FL).

This patent was filed on February 22, 2007 and was published online on May 20, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "A pressurized water Nuclear reactor (PWNR) has a core immersed in water in a large steel tank. The fuel rods and control rods make up a vertical array. The control rods are movable, and are pulled up above the fuel rods when the plant is in full operation. The purpose of the control rods is to absorb neutrons which trigger the splitting of atomic nuclei in the fissionable material in the fuel rods. With all the control rods inserted, there is negligible fission (and heating) in the fuel rods. When the control rods are pulled out the fuel rods heat the water, which is circulated by pumps in the primary or, inner loop, to a heat exchanger.

"A feature of this design is that only the water in the inner loop is in contact with the radioactive fuel rods. Thus, only the inner loop has contamination from the inevitable small amount of rust and corrosion. There are filters in this inner loop to capture the small particles which are radioactively contaminated. There are additional pumps to circulate cooling water through the core, which form the Emergency Core Cooling System (ECCS). It is essential that circulation be maintained to carry heat away from the fuel rods to prevent them from melting in the event that the main primary circulation pumps should fail. The water in the tank and the primary circulation loop is never supposed to boil, and thus always remain as water because steam is a much poorer conductor of heat as compared to water. The fuel rods are supposed to always stay under water. To prevent boiling, the tank and primary loop are maintained at very high pressure.

"The secondary loop water is heated through a heat exchanger with the primary loop. Water in the secondary loop is allowed to boil in a steam generator tank. The steam is used to drive a turbine which turns an electrical generator. The residual steam is condensed back to water, which is pumped back through the heat exchanger again to make more steam. Also, circulation usually through a large cooling tower which is used to remove the waste heat.

"One problem with conventional thermal transfer fluids used in PWNRs is the onset of a heat transfer condition that can lead to a departure from nuclei boiling (DNBR) that occurs at a condition call the critical heat flux. (CHF) which results in a blanketing of the fuel rod with bubbles that interferes with heat transfer and leads to a condition called dryout that can result in a critical failure of the fuel rods. What is needed is nanofluid having enhanced thermal transfer and stability for PWNRs to raise the heat flux level at which dryout condition will occur. This heat flux level is called the critical heat flux (CHF)."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "A pressurized water nuclear reactor comprises a core comprising a containment shield surrounding a reactor vessel having fuel assemblies that contain fuel rods filled with fuel pellets and control rods, and a steam generator thermally coupled to the reactor vessel. A flow loop comprises the steam generator, a turbine, and a condenser, and a pump for circulating a water-based heat transfer fluid in the loop. The heat transfer fluid comprises a plurality of nanoparticles comprising at least one carbon allotrope or related carbon material dispersed therein. As used herein, the phrase 'carbon allotrope or related carbon material' includes the carbon allotropes, such as diamond, graphite, lonsdaleite, fullerenses including C60, C540 and C70, amorphous carbon and carbon nanotube, and related materials including pyrolitic carbon, carbon black and diamond-like carbon. In some cases the allotrope or related material is functionalized, such as hydoxy-functionalized fullerenes to promote dispersion in solution.

"The diamond particles are typically primarily colloidal and have a mean size of 0.5 nm to 200 nanometers. In other embodiments of the invention the mean particle size is 1 nm to 100 nm, such as 40 nm to 100 nm. A concentration of nanoparticles can range from 0.0001 to 10 volume percent of the heat transfer fluid, such as from 0.1 to 3 volume percent of the heat transfer fluid.

"A method of transferring heat using a heat transfer fluid comprises the steps of providing a water based heat transfer fluid comprising a plurality of carbon allotrope or related carbon material dispersed therein, placing the heat transfer fluid in a system comprising a coolant loop including a heat source and a heat sink, and circulating the heat transfer fluid in the coolant loop during operation of the system. The system can comprise a pressurized water nuclear reactor."

For the URL and additional information on this patent, see: Baney, Ronald H.; Tulenko, James S.; Powers, Kevin W.. Nuclear Reactor Having Efficient and Highly Stable Thermal Transfer Fluid. U.S. Patent Number 8731133, filed February 22, 2007, and published online on May 20, 2014. Patent URL:

Keywords for this news article include: University of Florida Research Institute Foundation Inc.

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Source: Journal of Engineering