Evaluation of Serpent Capabilities for Hyperfidelity Depletion of Pebble Bed Cores

2021 ◽  
Author(s):  
Yves Robert ◽  
Massimiliano Fratoni
Keyword(s):  
Cross Sections ◽  
Memory Usage ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Regular Lattices ◽  
High Flexibility ◽  
Computing Machines ◽  
Monte Carlo Transport ◽  
Burnup Calculation ◽  
Made In

Abstract Accurate burnup calculation in pebble bed reactor cores is today necessary but challenging. The continuous advancement in computing capabilities make the use of Monte Carlo transport codes possible to efficiently study individual pebbles depletion without making strong assumptions. The purpose is to eliminate unnecessary typical assumptions made in existing codes, while being flexible and suitable for commonly available computing machines. Among the available codes, Serpent 2 provides extremely useful tools to make pebble beds modeling and simulation efficient. The explicit stochastic geometry definition handles irregular pebble beds with comparable performances to regular lattices. Optimization modes controlling the use of unionized energy grids, cross-sections pre-calculation and flux calculation through spectrum collapse or direct tally lead to high flexibility and optimal memory usage while limiting calculation time. Automated burnable materials division is a useful tool to lower the memory requirements while quickly generating the geometry and materials. Finally, parallelization and domain decomposition allow for decreasing unreasonable memory constraints for large cores. This work thus explores the possibilities of Serpent 2 when applying depletion in pebble beds, compares the optimization modes and quantifies the simulation time and memory usage depending on the conditions of the calculation. Overall, the results show that Serpent 2 is well adapted to the use of small to large cores calculations with commonly available resources.

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

Preliminary neutronic study on Pu-based OTTO cycle pebble bed reactor

Kerntechnik ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. 643-647 ◽  
Author(s):  
T. Setiadipura ◽  
D. Irwanto ◽  
Zuhair
Keyword(s):  
Otto Cycle ◽  
Pebble Bed ◽  
Pebble Bed Reactor

Effect of bed configuration on pebble flow uniformity and stagnation in the pebble bed reactor

2014 ◽  
Vol 270 ◽  
pp. 295-301 ◽  
Author(s):  
Nan Gui ◽  
Xingtuan Yang ◽  
Jiyuan Tu ◽  
Shengyao Jiang
Keyword(s):  
Flow Uniformity ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Flow

scholarly journals Two-Side Laser Processing Method for Producing High Aspect Ratio Microholes

2017 ◽  
Vol 5 (4) ◽  
Author(s):  
Vahid Nasrollahi ◽  
Pavel Penchev ◽  
Stefan Dimov ◽  
Lars Korner ◽  
Richard Leach ◽  
...  
Keyword(s):  
Cross Sections ◽  
Laser Processing ◽  
Industrial Applications ◽  
Laser Drilling ◽  
Special Focus ◽  
Geometrical Accuracy ◽  
Aspect Ratios ◽  
Wide Range ◽  
High Flexibility ◽  
Accuracy And Repeatability

Laser microprocessing is a very attractive option for a growing number of industrial applications due to its intrinsic characteristics, such as high flexibility and process control and also capabilities for noncontact processing of a wide range of materials. However, there are some constrains that limit the applications of this technology, i.e., taper angles on sidewalls, edge quality, geometrical accuracy, and achievable aspect ratios of produced structures. To address these process limitations, a new method for two-side laser processing is proposed in this research. The method is described with a special focus on key enabling technologies for achieving high accuracy and repeatability in two-side laser drilling. The pilot implementation of the proposed processing configuration and technologies is discussed together with an in situ, on-machine inspection procedure to verify the achievable positional and geometrical accuracy. It is demonstrated that alignment accuracy better than 10 μm is achievable using this pilot two-side laser processing platform. In addition, the morphology of holes with circular and square cross sections produced with one-side laser drilling and the proposed method was compared in regard to achievable aspect ratios and holes' dimensional and geometrical accuracy and thus to make conclusions about its capabilities.

V.—The Brookwood Deep-Well Section

1886 ◽  
Vol 3 (8) ◽  
pp. 353-357
Author(s):  
A. Irving
Keyword(s):  
Loamy Sand ◽  
Free Access ◽  
The South ◽  
Pebble Bed ◽  
Deep Well ◽  
Western Side ◽  
High Road ◽  
Made In ◽  
Geological Magazine

This section, which was completed last year, appears of such value and interest to students of the Tertiary strata of the London Basin, that I have thought it worth while to offer a description of it to the readers of the Geological Magazine. Through the courtesy of Dr. Barton, the Governor of the Asylum, I have had free access to the specimens preserved of the various strata passed through, and very careful use of them has been made in the preparation of the tabulated statement which follows; much of the information having been kindly furnished from the engineers who were employed. The Asylum is situated at Knap Hill, about a mile and a quarter from Brookwood Station on the South-Western Eailway, and is on the Upper Bagshot Sands. The mouth of the well is in the valley just below, about 140 feet above O. D., and about the same level as that at which the Middle Bagshot Beds occur in the famous Goldsworthy section, which furnished Prof. Prestwich, some forty years ago, with the clue to the succession of the beds of the Bagshot Formation. It is about a mile and a half distant therefrom. The evidence as to the horizon in the Bagshot Series, at which the well commences, is very clear to those who are familiar with the stratigraphy. The widely-extended pebble-bed at the base of the Upper Bagshot Sands occurs here very near the top of the well, and I saw it exposed again at about the same level in an excavation made by the side of the high road which runs along the western side of the Asylum Estate. The same greenish loamy sand was intermingled with the pebbles in both cases. In the ploughed field a stiff yellow loam, such as so commonly occurs above this pebble-bed in the Bagshot area, crops out in the valley where the well is situated. The ‘brown sandy bed’ which occurs at the top of the section is probably a portion of this, re-constructed by later drift action, and mingled with more sandy materials washed down from the sandy strata situated at higher levels on the slopes of the valley.

scholarly journals A Safety Re-Evaluation of the AVR Pebble Bed Reactor Operation and Its Consequences for Future HTR Concepts

2008 ◽  
Author(s):  
Rainer Moormann
Keyword(s):  
Fission Product ◽  
End Of Life ◽  
Fission Products ◽  
Normal Operation ◽  
Primary Circuit ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Hot Gas ◽  
Design Basis ◽  
Gas Tight

The AVR pebble bed reactor (46 MWth) was operated 1967–1988 at coolant outlet temperatures up to 990°C. Also because of a lack of other experience the AVR operation is a basis for future HTRs. This paper deals with insufficiently published unresolved safety problems of AVR and of pebble bed HTRs. The AVR primary circuit is heavily contaminated with dust bound and mobile metallic fission products (Sr-90, Cs-137) which create problems in current dismantling. The evaluation of fission product deposition experiments indicates that the end of life contamination reached several percent of a single core inventory. A re-evaluation of the AVR contamination is performed in order to quantify consequences for future HTRs: The AVR contamination was mainly caused by inadmissible high core temperatures, and not — as presumed in the past — by inadequate fuel quality only. The high AVR core temperatures were detected not earlier than one year before final AVR shut-down, because a pebble bed core cannot be equipped with instruments. The maximum core temperatures were more than 200 K higher than precalculated. Further, azimuthal temperature differences at the active core margin were observed, as unpredictable hot gas currents with temperatures &gt; 1100°C. Despite of remarkable effort these problems are not yet understood. Having the black box character of the AVR core in mind it remains uncertain whether convincing explanations can be found without major experimental R&D. After detection of the inadmissible core temperatures, the AVR hot gas temperatures were strongly reduced for safety reasons. Metallic fission products diffuse in fuel kernel, coatings and graphite and their break through takes place in long term normal operation, if fission product specific temperature limits are exceeded. This is an unresolved weak point of HTRs in contrast to other reactors and is particularly problematic in pebble bed systems with their large dust content. Another disadvantage, responsible for the pronounced AVR contamination, lies in the fact that activity released from fuel elements is distributed in HTRs all over the coolant circuit surfaces and on graphitic dust and accumulates there. Consequences of AVR experience on future reactors are discussed. As long as pebble bed intrinsic reasons for the high AVR temperatures cannot be excluded they have to be conservatively considered in operation and design basis accidents. For an HTR of 400 MWth, 900°C hot gas temperature, modern fuel and 32 fpy the contaminations are expected to approach at least the same order as in AVR end of life. This creates major problems in design basis accidents, for maintenance and dismantling. Application of German dose criteria on advanced pebble bed reactors leads to the conclusion that a pebble bed HTR needs a gas tight containment even if inadmissible high temperatures as observed in AVR are not considered. However, a gas tight containment does not diminish the consequences of the primary circuit contamination on maintenance and dismantling. Thus complementary measures are discussed. A reduction of demands on future reactors (hot gas temperatures, fuel burn-up) is one option; another one is an elaborate R&D program for solution of unresolved problems related to operation and design basis accidents. These problems are listed in the paper.

scholarly journals Modeling of Fuel Elements Cycling System in Pebble Bed Reactor Based on Timed Places Control Petri Nets

2013 ◽  
Vol 05 (04) ◽  
pp. 510-516
Author(s):  
Hongbing Liu ◽  
Peng Shen ◽  
Dong Du ◽  
Xin Wang ◽  
Haiquan Zhang
Keyword(s):  
Petri Nets ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Cycling System ◽  
Fuel Elements

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.

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