scholarly journals The implication of Thorium fraction on neutronic parameters of pebble bed reactor

2021 ◽  
Vol 48 (3) ◽  
Author(s):  
Zuhair Zuhair ◽  
◽  
R. Andika Putra Dwijayanto ◽  
Suwoto Suwoto ◽  
Topan Setiadipura ◽  
...  
Keyword(s):  
Neutron Transport ◽  
Neutron Generation ◽  
Neutron Lifetime ◽  
Reactor Model ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Bed Reactors ◽  
Fuel Burn ◽  
Neutronic Parameters ◽  
High Level

Thorium abundance in the Earth's crust is estimated to be three to four times higher than uranium. This is one potential advantage of Thorium as a provider of attractive fuel to produce nuclear energy. Fewer transuranics produced by Thorium during the fuel burn up in the reactor may also be another advantage for reducing the long-term burden of high-level long-lived waste. The scope of this paper is to study the implication of Thorium fraction on neutronic parameters of pebble bed reactor. The reactor model of HTR-10 was selected, and the (Th, 235U)O2 fuel was used in this study. The MCNP6 code was applied to solve a series of neutron transport calculations with various Thorium fractions in (Th,235U)O2 fuel based on the ENDF/BVII library. The calculation results show that the total temperature coefficient of reactivity of Thorium-added pebble bed reactors is generally more negative than those of LEU-fuelled one, except for 10% Thorium fraction. The kinetic parameters, especially prompt neutron lifetime and neutron generation time of pebble bed reactors, are higher, which means the addition of Thorium in the fuel makes the reactor more easily controlled. However, the burn-up calculations show that the introduction of Thorium in the same fuel kernel as LEU within the pebble bed reactor is unable to lengthen the fuel residence time, except for a minimum of 40% Thorium fraction.

scholarly journals Physical Analysis of the Initial Core and Running-In Phase for Pebble-Bed Reactor HTR-PM

2017 ◽  
Vol 2017 ◽  
pp. 1-6
Author(s):  
Jingyu Zhang ◽  
Fu Li ◽  
Yuliang Sun
Keyword(s):  
Physical Parameters ◽  
Physical Analysis ◽  
Fuel Management ◽  
Fuel Temperature ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Bed Reactors ◽  
Management Scheme ◽  
Typical Scheme ◽  
Scheme Evaluation

The pebble-bed reactor HTR-PM is being built in China and is planned to be critical in one or two years. At present, one emphasis of engineering design is to determine the fuel management scheme of the initial core and running-in phase. There are many possible schemes, and many factors need to be considered in the process of scheme evaluation and analysis. Based on the experience from the constructed or designed pebble-bed reactors, the fuel enrichment and the ratio of fuel spheres to graphite spheres are important. In this paper, some relevant physical considerations of the initial core and running-in phase of HTR-PM are given. Then a typical scheme of the initial core and running-in phase is proposed and simulated with VSOP code, and some key physical parameters, such as the maximum power per fuel sphere, the maximum fuel temperature, the refueling rate, and the discharge burnup, are calculated. Results of the physical parameters all satisfy the relevant design requirements, which means the proposed scheme is safe and reliable and can provide support for the fuel management of HTR-PM in the future.

scholarly journals Pebbles Making Waves

2008 ◽  
Vol 130 (02) ◽  
pp. 34-38
Author(s):  
Lee S. Langston
Keyword(s):  
South Africa ◽  
Power Plant ◽  
Packed Bed ◽  
Nuclear Fission ◽  
Reactor Power ◽  
Reactor Vessel ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
High Level ◽  
Reactor Power Plant

This paper describes various high-level nuclear researches including nuclear-fuelled pebbles that are being conducted across South Africa. The pebbles are ingenious industrial products, designed to passively limit the amount of heat unleashed by the nuclear fission reactions that drive the reactor. The spheres that give the pebble bed reactor its name enclose fissionable uranium inside layers that serve various roles, such as moderating fission, containing pressure, and accommodating deformation of the core. Nuclear-fuelled pebbles are introduced at the top of the reactor vessel and slowly wend their way down through the annular-packed bed under the action of gravity to the bottom of the reactor vessel. In a towering building at the headquarters of Nesca in Pelindaba, South Africa, reactor components are being tested for their ability to work with high-pressure helium. Those parts will go in the pebble bed modular reactor power plant to be constructed at Koeburg, near Cape Town. The plan of the pebble bed reactor power plant will use the helium coolant to run the turbine directly rather than heat a secondary fluid, as in a water reactor.

scholarly journals STUDY ON MCNP6 MODEL IN THE CALCULATION OF KINETIC PARAMETERS FOR PEBBLE BED REACTOR

2020 ◽  
Vol 60 (2) ◽  
pp. 175-184
Author(s):  
. Zuhair ◽  
. Suwoto ◽  
Topan Setiadipura ◽  
Zaki Su'ud
Keyword(s):  
Kinetic Parameters ◽  
Nuclear Reactor ◽  
Inherent Safety ◽  
Neutron Lifetime ◽  
Uranium Enrichment ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Monte Carlo Transport ◽  
Selection Of ◽  
Parameters Calculation

When conducting a nuclear reactor transient analysis, the most important parameter, called the kinetic parameter, is required. The calculation of kinetic parameters can be conducted using several methods. The deterministic method is one possible method that relies on the forward and adjoint neutron fluxes to provide the kinetic parameters calculation based on the perturbation theory. In this study, the Monte Carlo transport code MCNP6 was utilized to perform the exact prediction of the kinetic parameters of a pebble bed reactor. The core was modelled with a different fuel composition of uranium loading per pebble, <sup>235</sup>U enrichment and H/D ratio. It was found that <em>k</em>eff strongly depends on the uranium loading, uranium enrichment and H/D ratio while the <em>β</em>eff dependence is insignificant. The increase in the prompt neutron lifetime (ℓ) and mean generation time (Ʌ) as a function of H/D ratio are insignificant as compared to the decrease of those parameters in the case of uranium loading or uranium enrichment. These results conclude that the selection of uranium loading per pebble, <sup>235</sup>U enrichment and H/D ratio should be considered carefully for the control and inherent safety performances

scholarly journals The effects of fuel type on control rod reactivity of pebble-bed reactor

Nukleonika ◽  
2019 ◽  
Vol 64 (4) ◽  
pp. 131-138
Author(s):  
◽  
Topan Setiadipura ◽  
Jim C. Kuijper ◽  
Keyword(s):  
Reactor Core ◽  
Fuel Type ◽  
Reactor Model ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Control Rod ◽  
Reactor Geometry ◽  
Calculation Results ◽  
Control Rods ◽  
Selection Of

Abstract As a crucial core physics parameter, the control rod reactivity has to be predicted for the control and safety of the reactor. This paper studies the control rod reactivity calculation of the pebble-bed reactor with three scenarios of UO2, (Th,U)O2, and PuO2 fuel type without any modifications in the configuration of the reactor core. The reactor geometry of HTR-10 was selected for the reactor model. The entire calculation of control rod reactivity was done using the MCNP6 code with ENDF/B-VII library. The calculation results show that the total reactivity worth of control rods in UO2-, (U,Th)O2-, and PuO2-fueled cores is 15.87, 15.25, and 14.33%Δk/k, respectively. These results prove that the effectiveness of total control rod in thorium and uranium cores is almost similar to but higher than that in plutonium cores. The highest reactivity worth of individual control rod in uranium, thorium and plutonium cores is 1.64, 1.44, and 1.53%Δk/k corresponding to CR8, CR1, and CR5, respectively. The other results demonstrate that the reactor can be safely shutdown with the control rods combination of CR3+CR5+CR8+CR10, CR2+CR3+CR7+CR8, and CR1+CR3+CR6+CR8 in UO2-, (U,Th)O2-, and PuO2-fueled cores, respectively. It can be concluded that, even though the calculation results are not so much different, however, the selection of control rods should be considered in the pebble-bed core design with different scenarios of fuel type.

Spectral Zones Determination for Pebble Bed Reactor Cores Using Diffusion Theory Spectral Indices

2008 ◽  
Author(s):  
Ramatsemela Mphahlele ◽  
Abderrafi M. Ougouag ◽  
Kostadin N. Ivanov ◽  
Hans D. Gougar
Keyword(s):  
Diffusion Theory ◽  
Surface Fluxes ◽  
Spectral Indices ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Absolute Value ◽  
Pebble Bed Reactors ◽  
Spectral Changes ◽  
Diffusion Constants

A practical methodology is developed for the determination of spectral zones in Pebble Bed Reactors (PBR). The methodology involves the use of spectral indices based on few-group diffusion theory whole core calculations. In this work a spectral zone is defined as made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. Therefore, spectral indices that reflect the physical behaviors of interest can be used to characterize said behaviors within each zone and thus to identify and distinguish the spectral zones. Several plausible spectral indices have been investigated in this work. Special emphasis and focus was placed on the trend or behavior of the spectral index at various positions along the radial and axial dimensions in the core. The ratio of group-wise surface currents to total surface fluxes, has been used to successfully identify spectral zone boundaries. A plot of the absolute value of this ratio versus position in the reactor exhibits a series of minima and maxima points. These extrema correlate with regions of significant spectral changes, and therefore are identified as plausible spectral zone boundaries.

Gas-Cooled Modular Reactors With Spherical Fuel Elements — Their Inherent Safety and Applications Not Just for Power Generation

2014 ◽  
Author(s):  
Walter Jaeger ◽  
H. J. Hamel ◽  
Heinz Termuehlen
Keyword(s):  
Power Generation ◽  
High Temperature ◽  
Reactor Design ◽  
Inherent Safety ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Bed Reactors ◽  
Fuel Elements ◽  
High Temperature Gas

The gas-cooled reactor design with spherical fuel elements, referred to as high-temperature gas-cooled reactors (HTGR or HTR reactors) or pebble bed reactors has been already suggested by Farrington Daniels in the late 1940s; also referred to as Daniels’ pile reactor design. Under Rudolf Schulten the first pebble bed reactor, the 46MWth AVR Juelich reactor (Atom Versuchs-Reactor Jülich) was built in the late 1960s. It was in operation for 22 years and extensive testing confirmed its inherent safety.

scholarly journals A simulation of a pebble bed reactor core by the MCNP-4C computer code

2009 ◽  
Vol 24 (3) ◽  
pp. 177-182 ◽  
Author(s):  
Moshkbar Bakhshayesh ◽  
Naser Vosoughi
Keyword(s):  
Computing Time ◽  
Reactor Core ◽  
Computer Code ◽  
Critical Height ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Bed Reactors ◽  
New Generation ◽  
And Control ◽  
Control Rods

Lack of energy is a major crisis of our century; the irregular increase of fossil fuel costs has forced us to search for novel, cheaper, and safer sources of energy. Pebble bed reactors - an advanced new generation of reactors with specific advantages in safety and cost - might turn out to be the desired candidate for the role. The calculation of the critical height of a pebble bed reactor at room temperature, while using the MCNP-4C computer code, is the main goal of this paper. In order to reduce the MCNP computing time compared to the previously proposed schemes, we have devised a new simulation scheme. Different arrangements of kernels in fuel pebble simulations were investigated and the best arrangement to decrease the MCNP execution time (while keeping the accuracy of the results), chosen. The neutron flux distribution and control rods worth, as well as their shadowing effects, have also been considered in this paper. All calculations done for the HTR-10 reactor core are in good agreement with experimental results.

scholarly journals Initial prediction of dust production in pebble bed reactors

2011 ◽  
Vol 2 (2) ◽  
pp. 189-195 ◽  
Author(s):  
M. Rostamian ◽  
S. Arifeen ◽  
G. P. Potirniche ◽  
A. Tokuhiro
Keyword(s):  
Computational Simulation ◽  
Fission Products ◽  
Initial Attempt ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Bed Reactors ◽  
Safety Issues ◽  
Dust Generation ◽  
Very High Temperature Reactor ◽  
Very High

Abstract. This paper describes the computational simulation of contact zones between pebbles in a pebble bed reactor. In this type of reactor, the potential for graphite dust generation from frictional contact of graphite pebbles and the subsequent transport of dust and fission products can cause significant safety issues at very high temperatures around 900 °C in HTRs. The present simulation is an initial attempt to quantify the amount of nuclear grade graphite dust produced within a very high temperature reactor.

Proposal for an International Experimental Pebble Bed Reactor

2008 ◽  
Author(s):  
Dawid Serfontein ◽  
Eben Mulder ◽  
Eberhard Teuchert
Keyword(s):  
Carbon Fiber ◽  
Fuel Cycle ◽  
Heat Removal ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Bed Reactors ◽  
Fuel Cycles ◽  
Short Time Span ◽  
Enriched Uranium ◽  
Vessel Development

HTRs, both prismatic block fuelled and pebble fuelled, feature a number of uniquely beneficial characteristics that will be discussed in this paper. In this paper the construction of an international experimental pebble bed reactor is proposed, possible experiments suggested and an invitation extended to interested partners for co-operation in the project. Experimental verification by nuclear regulators in order to facilitate licensing and the development of a new generation of reactors create a strong need for such a reactor. Suggested experiments include: • Optimized incineration of waste Pu in a pebble bed reactor: The capability to incineration pure reactor grade plutonium by means of ultra high burn-up in pebble bed reactors will be presented at this conference in the track on fuel and fuel cycles. This will enable incineration of the global stockpile of separated reactor grade Pu within a relatively short time span; • Testing of fuel sphere geometries, aimed at improving neutron moderation and a decrease in fuel temperatures; • Th/Pu fuel cycles: Previous HTR programs demonstrated the viability of a Th-232 fuel-cycle, using highly enriched uranium (HEU) as driver material. However, considerations favoring proliferation resistance limit the enrichment level of uranium in commercial reactors to 20%, thereby lowering the isotopic efficiency. Therefore, Pu driver material should be developed to replace the HEU component. Instead of deploying a (Th, Pu)O2 fuel concept, the proposal is to use the unique capability offered by pebble bed reactors in deploying separate Th- and Pu-containing pebbles, which can be cycled differently; • Testing of carbon-fiber-carbon (CFC) structures for in-core or near-core applications, such as guide tubes for reserve shutdown systems, thus creating the possibility to safely shutdown reactors with increased diameter; • Development of very high temperature reactor components for process heat applications; • Advanced decay heat removal systems e.g. design specific air flow channels, or heat pipe designs external to the reactor pressure vessel; • Development of a plutonium fuelled peaking reactor with the proposed duel cycle; • A radial coolant flow pattern with increased power output; • Testing of carbon-fiber-carbon (CFC) core barrel applications. The design will facilitate ease of licensing by sacrificing performance in favor of safety and employing redundant defense-in-depth safety systems. Speedy licensing is therefore expected. The economic model will be based on a commercial expedition of the agreed experimental value to collaborating participants. Target costs will be minimized by exploiting known technology only and by utilizing off-the-shelf components as far as possible.

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