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Advanced In-Core Fuel Cycles for the Gas Turbine-Modular Helium Reactor
KTH, School of Engineering Sciences (SCI), Physics.
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

In 1789 a German chemist, Martin Heinrich Klaproth, announced the discovery of a new element: uranium; few years later, the head of father of the modern chemistry, Antoine Lavoisier, was swept away by guillotine: a new era was destined to be opened, either where energy would have been produced in large scale by nuclear processes delivering hundreds of times the energy of chemical processes or where a mass of people, revolutionary or not, would have been melted down into a couple of seconds. After a quite long time, on the 2nd December 1942, the first nuclear reactor has been put into operation by Enrico Fermi in Chicago; few years later, came also the dark side utilization of fissile materials in Hiroshima and Nagasaki. Since those moments, three power plants generations succeeded, until the current one which is the generation IV of nuclear reactors. The latter has the goal of generating electricity in a safe manner, for the core is designed to provide an effective passive cooling of the decay heat. Amid generation IV of nuclear power plants, the Gas Turbine – Modular Helium Reactor, designed by General Atomics, is the only core with an energy conversion efficiency of 50%; the above consideration, coupled to construction and operation costs lower than ordinary Light Water Reactors, renders the Gas Turbine – Modular Helium reactor rather unequaled.

In the present studies we investigated the possibility to operate the GT-MHR with two types of fuels: LWRs waste and thorium; since thorium is made of only fertile 232Th, we tried to mix it with pure 233U, 235U or 239Pu; ex post facto, only uranium isotopes allow the reactor operation, that induced us to examine the possibility to use a mixture of uranium, enriched 20% in 235U, and thorium. We performed all calculations by the MCNP and MCB codes, which allowed to model the reactor in a very detailed threedimensional geometry and to describe the nuclides transmutation in a continuous energy approach; finally, we completed our studies by verifying the influence of the major nuclear data libraries, JEFF, JENDL and ENDF/B, on the obtained results.

Place, publisher, year, edition, pages
Stockholm: KTH , 2006. , x,60 p.
Series
TRITA-FYS, ISSN 0280-316X ; 2006.25
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-3901ISBN: 91-7178-328-8 (print)OAI: oai:DiVA.org:kth-3901DiVA: diva2:9951
Public defence
2006-04-21, Sal FA31, AlvaNova, Roslagstullsbacken 21, Stockholm, 14:00
Opponent
Supervisors
Note

QC 20100922

Available from: 2006-04-05 Created: 2006-04-05 Last updated: 2014-12-17Bibliographically approved
List of papers
1. The burnup capabilities of the deep burn modular helium reactor analyzed by the Monte Carlo continuous energy code MCB
Open this publication in new window or tab >>The burnup capabilities of the deep burn modular helium reactor analyzed by the Monte Carlo continuous energy code MCB
2004 (English)In: Annals of nuclear energy, ISSN 0029-5639, Vol. 31, no 2, 173-196 p.Article in journal (Refereed) Published
Abstract [en]

In the future development of nuclear energy, the graphite-moderated helium-cooled reactors may play an important role because of their valuable technical advantages: passive safety, low cost, flexibility in the choice of fuel, high conversion energy efficiency, high burnup, more resistant fuel cladding, and low power density. General Atomics possesses a long experience with this type of reactor, and it has recently developed the gas turbine-modular helium reactor (GT-MHR), a design where the nuclear power plant is structured into four reactor modules of 600 MW(thermal). Amid its benefits, the GT-MHR offers a rather large flexibility in the choice of fuel type; Th, U, and Pu may be used in the manufacture of fuel with some degrees of freedom. As a consequence, the fuel management may be designed for different objectives aside from energy production, e.g., the reduction of actinide waste production through a fuel based on thorium. In our previous studies we analyzed the behavior of the GT-MHR with a plutonium fuel based on light water reactor (LWR) waste; in the present study we focused on the incineration of military Pu. This choice of fuel requires a detailed numerical modeling of the reactor since a high value of keff at the beginning of the reactor operation requires the modeling both of control rods and of burnable poison; by contrast, when the GT-MHR is fueled with LWR waste, at the equilibrium of the fuel composition, the reactivity swing is small.

Keyword
Monte Carlo method, Modular design, Burnup, Three dimensional model, Military application, Plutonium, Incineration, Gas turbine, Helium cooled reactors, Nuclear reactor
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-5543 (URN)10.1016/S0306-4549(03)00213-5 (DOI)000186662100005 ()2-s2.0-0141818957 (Scopus ID)
Note

QC 20100922

Available from: 2006-04-05 Created: 2006-04-05 Last updated: 2014-12-17Bibliographically approved
2. Key Physical Parameters and Temperature Reactivity Coefficients of the Deep Burn Modular Helium Reactor Fueled with LWRs Waste
Open this publication in new window or tab >>Key Physical Parameters and Temperature Reactivity Coefficients of the Deep Burn Modular Helium Reactor Fueled with LWRs Waste
2004 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 31, 1913-1931 p.Article in journal (Refereed) Published
Abstract [en]

We investigated some important neutronic features of the deep burn modular helium reactor (DB-MHR) using the MCNP/MCB codes. Our attention was focused on the neutron flux and its spectrum, capture to fission ratio of Pu-239 and the temperature coefficient of fuel and moderator. The DB-MHR is a graphite-moderated helium-cooled reactor proposed by General Atomic to address the need for a fast and efficient incineration of plutonium for nonproliferation purposes as well as the management of light water reactors (LWRs) waste. In fact, recent studies have shown that the use of the DB-MHR coupled to ordinary LWRs would keep constant the world inventory of plutonium for a reactor fleet producing 400 TWe/y. In the present studies, the DB-MHR is loaded with Np-Pu driver fuel (DF) with an isotopic composition corresponding to LWRs spent fuel waste. DF uses fissile isotopes (e.g. Pu-239 and Pu-241), previously generated in the LWRs, and maintains criticality conditions in the DB-MHR. After an irradiation of three years, the spent DF is reprocessed and its remaining actinides are manufactured into fresh transmutation fuel (TF). TF mainly contains non-fissile actinides which undergo neutron capture and transmutation during the subsequent three-year irradiation in the DB-MHR. At the same time, TF provides control and negative reactivity feedback to the reactor. After extraction of the spent TF, irradiated for three years, over 94% of Pu-239 and 53% of all actinides coming from LWRs waste will have been destroyed in the DB-MHR. In this paper we look at the operation conditions at equilibrium for the DB-MHR and evaluate fluxes and reactivity responses using state of the art 3-D Monte Carlo simulations.

Keyword
coated particle fuel, gas-cooled reactors, nuclear-waste, monte-carlo, behavior, htgr, transmutation, elements, release, safety
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-5544 (URN)10.1016/j.anucene.2004.05.006 (DOI)000224257800006 ()2-s2.0-4444238018 (Scopus ID)
Note
QC 20100922 QC 20110915Available from: 2006-04-05 Created: 2006-04-05 Last updated: 2017-11-21Bibliographically approved
3. Comparative Studies of ENDF/B-6.8, JEF-2.2 and JENDL-3.2 Data Libraries by Monte Carlo Modeling of High Temperature Reactors on Plutonium Based Fuel Cycles
Open this publication in new window or tab >>Comparative Studies of ENDF/B-6.8, JEF-2.2 and JENDL-3.2 Data Libraries by Monte Carlo Modeling of High Temperature Reactors on Plutonium Based Fuel Cycles
2004 (English)In: Journal of Nuclear Science and Technology, ISSN 0022-3131, E-ISSN 1881-1248, Vol. 41, no 12, 1228-1236 p.Article in journal (Refereed) Published
Abstract [en]

We performed a numerical comparative analysis of the burnup capability of the Gas Turbine-Modular Helium Reactor (GT-MHR) by the Monte Carlo Continuous Energy Burnup Code (MCB). The MCB code is an extension of MCNP that includes the burnup implementation; it adopts continuous energy cross sections and it evaluates the transmutation trajectories for over 2,400 decaying nuclides. We equipped the MCB code with three different nuclear data libraries: JENDL-3.2, JEF-2.2 and ENDF/B-6.8 processed for temperatures from 300 to 1,800 K.

The GT-MHR model studied in this paper is fueled by actinides coming from the Light Water Reactors waste, converted into two different types of fuel: Driver Fuel and Transmutation Fuel. The Driver Fuel supplies the fissile nuclides needed to maintain the criticality of the reactor, whereas the Transmutation Fuel depletes non-fissile isotopes and controls reactivity excess. We set the refueling and shuffling period to one year and the in-core fuel residency time to three years.

The comparative analysis of the MCB code consists of accuracy and precision studies. In the accuracy studies, we performed the burnup calculation with different nuclear data libraries during the year at which the refueling and shuffling schedule set the equilibrium of the fuel composition. In the precision studies, we repeated the same simulations 20 times with a different pseudorandom number stride and the same nuclear data library.

Keyword
GT-MHR, JENDL, JEF, ENDF/B, TRISO, gas-cooled, graphite-moderated, plutonium, burnup
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-5545 (URN)10.3327/jnst.41.1228 (DOI)000227001800012 ()2-s2.0-13244277620 (Scopus ID)
Note
QC 20100922Available from: 2006-04-05 Created: 2006-04-05 Last updated: 2017-11-21Bibliographically approved
4. Performance of the Gas Turbine – Modular Helium Reactor fuelled with different types of fertile TRISO particles
Open this publication in new window or tab >>Performance of the Gas Turbine – Modular Helium Reactor fuelled with different types of fertile TRISO particles
2005 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 32, no 16, 1719-1749 p.Article in journal (Refereed) Published
Abstract [en]

Preliminary studies have been performed on operation of the gas turbine-modular helium reactor (GT-MHR) with a thorium based fuel. The major options for a thorium fuel are a mixture with light water reactors spent fuel, mixture with military plutonium or with with fissile isotopes of uranium. Consequently, we assumed three models of the fuel containing a mixture of thorium with 239Pu, 233U or 235U in TRISO particles with a different kernel radius keeping constant the packing fraction at the level of 37.5%, which corresponds to the current compacting process limit. In order to allow thorium to act as a breeder of fissile uranium and ensure conditions for a self-sustaining fission chain, the fresh fuel must contain a certain quantity of fissile isotope at beginning of life; we refer to the initial fissile nuclide as triggering isotope. The small capture cross-section of 232Th in the thermal neutron energy range, compared to the fission one of the common fissile isotopes (239Pu, 233U and 235U), requires a quantity of thorium 25-30 times greater than that one of the triggering isotope in order to equilibrate the reaction rates. At the same time, the amount of the triggering isotope must be enough to set the criticality condition of the reactor. These two conditions must be simultaneously satisfied. The necessity of a large mass of fuel forces to utilize TRISO particles with a large radius of the kernel, 300 μm. Moreover, in order to improve the neutron economics, a fuel cycle based on thorium requires a low capture to fission ratio of the triggering isotope. Amid the common fissile isotopes, 233U, 235U and 239Pu, we have found that only the uranium nuclides have shown to have the suitable neutronic features to enable the GT-MHR to work on a fuel based on thorium.

Keyword
Fission reactions, Gas turbines, Helium, Light water reactors, Plutonium, Radioisotopes, Spent fuels, Thorium, Uranium
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-5546 (URN)10.1016/j.anucene.2005.06.006 (DOI)000233056800002 ()2-s2.0-27144433532 (Scopus ID)
Note
QC 20100922Available from: 2006-04-05 Created: 2006-04-05 Last updated: 2017-11-21Bibliographically approved
5. Comparative Studies of JENDL-3.3, JENDL-3.2, JEFF-3, JEF-2.2 and ENDF/B-6.8 Data Libraries on the Monte Carlo Continuous Energy Modeling of the Gas Turbine - Modular Helium Reactor Operating with Thorium Fuel
Open this publication in new window or tab >>Comparative Studies of JENDL-3.3, JENDL-3.2, JEFF-3, JEF-2.2 and ENDF/B-6.8 Data Libraries on the Monte Carlo Continuous Energy Modeling of the Gas Turbine - Modular Helium Reactor Operating with Thorium Fuel
2005 (English)In: Journal of Nuclear Science and Technology, ISSN 0022-3131, E-ISSN 1881-1248, Vol. 42, no 12, 1040-1053 p.Article in journal (Refereed) Published
Abstract [en]

One of the major benefits of the Gas Turbine-Modular Helium Reactor is the capability to operate with several different types of fuel; either Light Water Reactors waste, military plutonium or thorium represent valid candidates as possible types of fuel. In the present studies, we performed a comparison of various nuclear data libraries by the Monte Carlo Continuous Energy Burnup Code MCB applied to the Gas Turbine-Modular Helium Reactor operating on a thorium fuel. A thorium fuel offers valuable attractive advantages: low fuel cost, high reduction of actinides production and the possibility to enable the reactor to act as a breeder of fuel by the neutron capture of fertile Th-232. We evaluated the possibility to mix thorium with small quantities, about 3% in atomic composition, of Pu-239, U-233 and U-235. The mass of thorium must be much larger than that one of plutonium or uranium because of the low capture cross section of thorium compared to the fission one of the fissile nuclides; at the same time, the quantity of the fissile isotopes must grant the criticality condition. These two simultaneous constraints force to load a huge mass of fuel in the reactor; consequently, we propose to allocate the fuel in TRISO particles with a large radius of the kernel. For each of the three different fuels we calculated the evolution of the fuel composition by the MCB code equipped with five different nuclear data libraries: JENDL-3.3, JENDL-3.2, JEFF-3, JEF-2.2 and ENDF/B.

Keyword
GT-MHR, JENDL, JEF, JEFF, ENDF/B, TRISO, gas-cooled, graphite-moderated, thorium
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-5547 (URN)10.3327/jnst.42.1040 (DOI)000235408400005 ()2-s2.0-32444444500 (Scopus ID)
Note
QC 20100922Available from: 2006-04-05 Created: 2006-04-05 Last updated: 2017-11-21Bibliographically approved
6. Adapting the Deep Burn In-Core Fuel Management Strategy for the Gas Turbine - Modular Helium Reactor to a Uranium-Thorium Fue
Open this publication in new window or tab >>Adapting the Deep Burn In-Core Fuel Management Strategy for the Gas Turbine - Modular Helium Reactor to a Uranium-Thorium Fue
2005 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 32, no 16, 1750-1781 p.Article in journal (Refereed) Published
Abstract [en]

In 1966, Philadelphia Electric has put into operation the Peach Bottom I nuclear reactor, it was the first high temperature gas reactor (HTGR); the pioneering of the helium-cooled and graphite-moderated power reactors continued with the Fort St. Vrain and THTR reactors, which operated until 1989. The experience on HTGRs lead General Atomics to design the gas turbine - modular helium reactor (GT-MHR), which adapts the previous HTGRs to the generation IV of nuclear reactors. One of the major benefits of the GT-MHR is the ability to work on the most different types of fuels: light water reactors waste, military plutonium, MOX and thorium. In this work, we focused on the last type of fuel and we propose a mixture of 40% thorium and 60% uranium. In a uranium-thorium fuel, three fissile isotopes mainly sustain the criticality of the reactor: U-235, which represents the 20% of the fresh uranium, U-233, which is produced by the transmutation of fertile Th-212, and Pu-239, which is produced by the transmutation of fertile U-238. In order to compensate the depletion of U-235 with the breeding of U-233 and Pu-239, the quantity of fertile nuclides must be much larger than that one of 235 U because of the small capture cross-section of the fertile nuclides, in the thermal neutron energy range, compared to that one of U-235. At the same time, the amount of U-235 must be large enough to set the criticality condition of the reactor. The simultaneous satisfaction of the two above constrains induces the necessity to load the reactor with a huge mass of fuel; that is accomplished by equipping the fuel pins with the JAERI TRISO particles. We start the operation of the reactor with loading fresh fuel into all the three rings of the GT-MHR and after 810 days we initiate a refueling and shuffling schedule that, in 9 irradiation periods, approaches the equilibrium of the fuel composition. The analysis of the k(eff) and mass evolution, reaction rates, neutron flux and spectrum at the equilibrium of the fuel composition, highlights the features of a deep burn in-core fuel management strategy for a uranium-thorium fuel.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-5548 (URN)10.1016/j.anucene.2005.07.002 (DOI)000233056800003 ()2-s2.0-27144468977 (Scopus ID)
Note
QC 20100922Available from: 2006-04-05 Created: 2006-04-05 Last updated: 2017-11-21Bibliographically approved
7. Managing the Reactivity Excess of the Gas Turbine – Modular Helium Reactor by Burnable Poison and Control Rods
Open this publication in new window or tab >>Managing the Reactivity Excess of the Gas Turbine – Modular Helium Reactor by Burnable Poison and Control Rods
2006 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 33, no 1, 84-98 p.Article in journal (Refereed) Published
Abstract [en]

The gas turbine-modular helium reactor coupled to the deep burn in-core fuel management strategy offers the extraordinary capability to incinerate over 50% of the initial inventory of fissile material. This extraordinary feature, coming from an advanced and well tested fuel element design, which takes advantage of the TRISO particles technology, is maintained while the reactor is loaded with the most different types of fuels. In the present work, we assumed the reactor operating at the equilibrium of the fuel composition, obtained by a 6 years irradiation of light water reactor waste, and we investigated the effects of the introduction of the burnable poison and the control rods; we equipped the core with all the three types of control rods: operational, startup and shutdown ones. We employed as burnable poison natural erbium, due to the Er-167 increasing neutron capture microscopic cross-section in the energy range where the neutron spectrum exhibits the thermal peak; in addition, we utilized boron carbide, with 90% enrichment in 1013, as the absorption material of the control rods. Concerning the burnable poison studies, we focused on the k(eff) value, the Er-167 mass during burnup, the influence of modifying the radius of the BISO particles kernel and the fuel and moderator coefficients of temperature. Concerning the control rods studies, we investigated the reactivity worth, the changes in the neutron flux profile due to a partial insertion, the influence of modifying the radius of the BISO particles kernel and the beta(eff), at the beginning of the operation

Keyword
deep-burn, monte-carlo, nuclear-waste, fuel, htr, transmutation, features, project, core
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-5549 (URN)10.1016/j.anucene.2005.08.005 (DOI)000234259100010 ()2-s2.0-28244447052 (Scopus ID)
Note
QC 20100922Available from: 2006-04-05 Created: 2006-04-05 Last updated: 2017-11-21Bibliographically approved

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