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Title: A point kinetics model for dynamic simulations of next generation nuclear reactor

Authors:
ORCiD logo;
Publication Date:
Sponsoring Org.:
USDOE Office of Electricity Delivery and Energy Reliability (OE), Power Systems Engineering Research and Development (R&D) (OE-10)
OSTI Identifier:
1359775
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Progress in Nuclear Energy
Additional Journal Information:
Journal Volume: 92; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 09:11:13; Journal ID: ISSN 0149-1970
Publisher:
Elsevier
Country of Publication:
United Kingdom
Language:
English

Citation Formats

El-Genk, Mohamed S., and Tournier, Jean-Michel P. A point kinetics model for dynamic simulations of next generation nuclear reactor. United Kingdom: N. p., 2016. Web. doi:10.1016/j.pnucene.2016.07.007.
El-Genk, Mohamed S., & Tournier, Jean-Michel P. A point kinetics model for dynamic simulations of next generation nuclear reactor. United Kingdom. doi:10.1016/j.pnucene.2016.07.007.
El-Genk, Mohamed S., and Tournier, Jean-Michel P. 2016. "A point kinetics model for dynamic simulations of next generation nuclear reactor". United Kingdom. doi:10.1016/j.pnucene.2016.07.007.
@article{osti_1359775,
title = {A point kinetics model for dynamic simulations of next generation nuclear reactor},
author = {El-Genk, Mohamed S. and Tournier, Jean-Michel P.},
abstractNote = {},
doi = {10.1016/j.pnucene.2016.07.007},
journal = {Progress in Nuclear Energy},
number = C,
volume = 92,
place = {United Kingdom},
year = 2016,
month = 9
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.pnucene.2016.07.007

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  • The method of point reactor kinetics in conjunction with the new concepts of delayed spectrum factor and beta growth factor is used to calculate the sensitivity of the dynamic behavior of a fast breeder reactor to large changes in delayed neutron energies following postulated reactivity accidents. The positive ramp rates are introduced not to simulate physical possibilities but solely to test the sensitivity to delayed neutron spectral changes under different conditions. A limited number of transient calculations are made using the point-kinetics code SENSTVTY, six precursor groups, and Doppler feedback. The calculational method and the reactor model are described. Delayedmore » neutron requirements in reactor dynamics are discussed, and a brief review of the sensitivity studies is presented. The results of the sensitivity calculations indicate that the relative power, the peak power, and the accident energy release are sensitive to changes in {beta}{sub eff} resulting from uncertainty in the delayed spectral data, but the sensitivity of the relative power is much greater than the peak power and the accident energy release. The spread in the maximum reactivity reached is found to be {approximately}18%, and the time spread in the melting of fuel and cladding is in milliseconds.« less
  • Few new orders for nuclear power plants have been placed anywhere in the world in the last 20 years, but that is not discouraging Raytheon Engineers Constructors from making plans to explore new light water reactor technologies for commercial markets. The Lexington, Mass.-based company, which has extensive experience in nuclear power engineering and construction, has a vision for the light water reactor of the future - one that is based on the use of thorium-232, an element that decays over several steps to uranium-233. The use of thorium and a small amount of uranium that is 20 percent enriched ismore » seen as providing operational, environmental, and safety advantages over reactors using the standard fuel mixture of uranium-238 and enriched uranium-235. According to Raytheon, the system could improve the economics of some reactors' operations by reducing fuel costs and lowering related waste volumes. At the same time, reactor safety could be improved by simpler control rod systems and the absence from reactor coolant of corrosive boric acid, which is used to slow neutrons in order to enhance reactions. Using thorium is also attractive because more of the fuel is burned up by the reactor, an estimated 12 percent as compared to about 4 percent for U-235. However, the technology's greatest attraction may well be its implications for nuclear proliferation. Growing plutonium inventories embedded in spent fuel rods from light water reactors have sparked concern worldwide. But according to Raytheon, using a thorium-based fuel core would alleviate this concern because it would produce only small quantities of plutonium. A thorium-based fuel system would produce 12 kilograms of plutonium over a decade versus 2,235 kilograms for an equivalent reactor operating with conventional uranium fuel.« less
  • Nuclear energy has not become the preferred method of electrical energy production largely because of economic, safety, and proliferation concerns and challenges posed by nuclear waste disposal. Economies is the most important factor. To reduce the capital costs, the authors propose a compact configuration with a very high power density and correspondingly reduced reactor component sizes. Enhanced efficiency made possible by higher operating temperatures will also improve the economics of the design, and design simplicity will keep capital, operational, and maintenance costs down. The most direct solution to the nuclear waste problem is to eliminate waste production or, at least,more » minimize its amount and long-term radiotoxicity. This can be achieved by very high burnups, ideally 100%, and by the eventual transmutation of the long-lived fission products in situ. Very high burnups also improve the economics by optimal exploitation of the fuel. Safety concerns can be addressed by an inherently safe reactor design. Because of the intrinsic nature of nuclear materials, there probably is no definitive answer to proliferation concerns for systems that generate neutrons; however, it is important to minimize proliferation risks. The thorium cycle is a promising option because (a) plutonium is produced only in very small quantities, (b) the presence of {sup 232}U makes handling the fuel very difficult and therefore proliferation resistant, and (c) {sup 233}U is a fissile isotope that is less suitable than {sup 239}Pu for making weapons and can be diluted with other uranium isotopes. An additional benefit of the thorium cycle is that it increases nuclear fuel resources by one order of magnitude. A fast flux fluid fuel reactor is a concept that can satisfy all the foregoing requirements. The fluid fuel systems have a very simple structure. Because integrity of the fuel is not an issue, these systems can operate at very high temperatures, can have high power densities, and can achieve very high burnups. It is possible to continuously remove the fission products and to minimize maintenance requirements. Fluid fuel systems possess favorable in-core transient response via a very high immediate negative temperature coefficient because of the expansion of the liquid fuel. Control rods are not necessary because the loss of reactivity can be compensated for by adding fuel in the on-line circuit. The main challenges posed by fluid fuel systems are possible fluctuations of reactivity caused by density changes, loss of delayed neutrons in the fuel leaving the core for the on-line reprocessing circuit, and corrosion and erosion of the containers. The fast flux choice is dictated by the much better neutronic economy offered by a hard spectrum system. The system is flexible enough to be either a burner, a converter, or a breeder. The fast spectrum is the only one that will allow all the transuranics to be efficiently burned. Moreover, because of the very high operating temperatures (1,000 C or more), refractory metals have to be used for the container. These materials have quite large absorption cross sections in the thermal and epithermal range. Therefore, they can be used only in a hard spectrum system without compromising the neutronic efficiency. Two different types of fast flux fluid fuel reactors are being considered: liquid-metal fluid fuel reactors and molten salt reactors.« less
  • The traditional version of the ..cap alpha.. method is based on a point one-group kinetic model of reactivity. In fast reactors with a moderating reflector this method is inapplicable because of the strong dependence of the neutron generation time in the region of asymptotic neutron flux decay on the subcriticality. In this paper the authors modify the alpha method to a two-group point kinetic model with a corresponding modification of the measurement procedure in order to extend the method to this class of reactors. The modifications are tested against experimental results of pulsed investigations on a BFS-40 fast critical pilemore » with a beryllium reflector.« less