Advances in the computation of the Sjöstrand, Rossi, and Feynman distributions

Talamo, Alberto; Gohar, Y.; Gabrielli, F.; Rineiski, A.; Pyeon, Cheol Ho

doi:10.1016/j.pnucene.2017.01.006

Cited by 16 publications

(12 citation statements)

References 12 publications

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“…In the present article, the authors propose a new method of designing the quasi-mono-isotopic detector set for a new subcritical reactor. The method is based on: -precise computer calculations of the reactor eigenvalue -k kcode and delayed neutron fraction - (using MCNP KCODE) and multiple simulations of the Sjöstrand experiment for all planned detector positions and for several possible sensitive detector materials (using the Talamo et al methodology [10]), resulting in values of k eff and differences  k kcode  k eff . As a result, for each detector position, a sensitive material with the lowest absolute value of  is selected, and from multiple evaluations, the most frequently selected material for a given position/detector is proposed for application.…”

Section: Discussionmentioning

confidence: 99%

“…First, detector positions in the well-defi ned reactor computer model should be proposed. Then, in the optimization procedure, from a set of fi ssile and fi ssionable nuclides and possibly other materials like natural uranium, 10 B, and others, one nuclide or material for each detector is selected. The computer simulation of Sjöstrand area method experiment is used to fi nd a detector response for each material of the assumed set.…”

Section: Monoisotopic Chambersmentioning

confidence: 99%

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Fission chambers for space effect reduction in the application of the area method: A new approach

2020

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The possibility of preparing fission chambers for the experimental determination of subcriticality without time-consuming corrections has been presented. The reactor detectors set consists of monoisotopic chambers. Each chamber is intended for a specific position in the system. Individual weights, rated a priori for all detectors in their positions, allow for quick calculation of whole system subcriticality. The inconveniences related to the spatial effect are minimized. This is achieved by computational simulation of the area method results, for each detector position and all possible fissionable and fissile nuclides. Next, one nuclide is selected, specific for the given position, presenting the smallest difference from the MCNP KCODE precisely estimated kkcode. The case study is made using the model of VENUS-F core.

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Section: Discussionmentioning

confidence: 99%

Section: Monoisotopic Chambersmentioning

confidence: 99%

Fission chambers for space effect reduction in the application of the area method: A new approach

2020

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“…Computer simulations of the Sjo ¨strand method experiments should be used to determine the detector response for each material and for all detectors and their positions in the reactor. Numerical simulations were carried out as described in [14] and [9], assuming the detector positions shown in Fig. 1.…”

Section: Mono Isotopic Chambersmentioning

confidence: 99%

Sensitivity of the area method with mono isotopic fission chambers to reactivity changes in subcritical nuclear reactors

2021

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High-level waste is an important safety issue in the development of nuclear power. A proposed solution is the transmutation of waste in fast reactors. The exclusion of the risk of supercriticality by using subcritical reactors is currently under development. Controlling the subcriticality level in such reactors presents difficulties. A problem is posed by the so-called space effect observed when using in reactors many neutron detectors in different locations of the core and reflector. Reactivity obtained from measurements, for example, by the Sjöstrand method, differs by nonnegligible values. Numerical corrections can partially improve this situation. The use of a monoisotopic fission chamber set, designed for a given reactor, when each chamber is intended for a specific position in the system, can improve the situation. A question arises about the sensitivity of the results to reactivity changes. This issue is analyzed by computer simulation for possible fissionable and fissile nuclides for the total range of control rod insertion, changes in reactor fuel enrichment, and fuel temperature. The tested sensitivity was satisfactory at most levels from several dozen to several hundred pcm. A case study was conducted using the VENUS-F core model.

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“…This is exhibited in experimental ADS, where measurements of neutron fluxes show that the properties of the proton source used for producing spallation neutrons strongly influence the time and spatial distributions of neutrons within the core [10]. In general, an approach with an explicit time dependence may be required, for instance when assessing the effect of security devices or when studying the impact of the protron source on the critical properties of the nuclear core [11,12].…”

Section: Introductionmentioning

confidence: 99%

“…The multiplication factor characterizing the growth of neutron fluxes is defined from this time evolution operator. The question then arises of relating the corresponding properties of neutron fluxes, which can be locally measured, to the parameters which characterize the global state of the nuclear core in a time independent way, in particular with respect to criticality [12].…”

Section: Introductionmentioning

confidence: 99%

The criticality of multiplicative processes

Gaveau,

Jaekel,

Maillard

et al. 2018

Preprint

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Keeping in view applications to numerical simulations of the evolution of a nuclear reactor core around criticality, we use a general mathematical framework for describing the evolutions of multiplicative processes (processes involving particle creation) both in particle generations and in time. This framework allows us to obtain, within a same formalism, two corresponding estimates of the multiplication factor which describes the growth of particle numbers at large times. We obtain the relative positions of both estimates with respect to each other and to criticality. These relations may show particularly useful when simulating in a realistic way the monitoring of nuclear cores in subcritical states, such as is the case for Accelerator Driven Systems (ADS). More generally, this study applies to various multiplicative processes which can be found in nature.

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Advances in the computation of the Sjöstrand, Rossi, and Feynman distributions

Cited by 16 publications

References 12 publications

Fission chambers for space effect reduction in the application of the area method: A new approach

Fission chambers for space effect reduction in the application of the area method: A new approach

Sensitivity of the area method with mono isotopic fission chambers to reactivity changes in subcritical nuclear reactors

The criticality of multiplicative processes

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