Impact of Approximations in Operating History Data on Spent Fuel Properties with Serpent 2

2021 ◽  
Author(s):  
Silja Häkkinen
Keyword(s):  
Spontaneous Fission ◽  
Spent Nuclear Fuel ◽  
Emission Rate ◽  
Photon Emission ◽  
Fuel Properties ◽  
Fission Rate ◽  
Decay Heat ◽  
Activity Decay ◽  
Operating History ◽  
Assembly Activity

Abstract In this work, the effect of averaging operating history parameters such as power history, boron concentration and coolant density and temperature on spent nuclear fuel properties was investigated. The examined properties were assembly activity, decay heat, photon emission rate, spontaneous fission rate and the concentration of some mobile nuclides and fissile nuclides. Calculations were performed on two similar VVER-440 fuel assemblies irradiated in different positions of the core using Serpent 2. Averaging power history over the entire irradiation history had a significant effect on assembly activity, decay heat and photon emission rate overestimating these properties approximately 70 % right after irradiation. However, the effect quickly died out and after 10 years of cooling the effect was less than 1 %. If the last cycle (3rd cycle) was modelled accurately and the power density of only the first two cycles were averaged, the differences remained always below 1 %. The effect of operating history approximations on spontaneous fission rate and the nuclide concentrations was much smaller reamaining mostly below 1.5 %. The sensitivity of nuclide concentrations to approximations in individual operating history parameters was dependent on the nuclide in question and no trend applying to all studied nuclides could be observed.

The Effect of Serpent 2 Calculation Parameters on Evaluated Spent Nuclear Fuel Source Term

2021 ◽  
Author(s):  
Riku Tuominen ◽  
Ville Valtavirta
Keyword(s):  
Source Term ◽  
Spent Nuclear Fuel ◽  
Photon Emission ◽  
Relative Difference ◽  
Fission Rate ◽  
Decay Heat ◽  
Probability Table ◽  
Zone Division ◽  
Energy Dependent ◽  
Fuel Source

Abstract The estimation of spent nuclear fuel source term (decay heat, reactivity, nuclide inventory etc.) has several sources of uncertainty such as uncertainties in nuclear data, uncertainties in the operation history, choice of calculation parameters etc. In this work the effect of calculation parameters is studied by estimating the source term with the built-in burnup capability of Serpent. The effect of the following parameters is considered: depletion zone division, burnup steps, unresolved resonance probability table sampling, Doppler-Broadening Rejection Correction (DBRC) and energy dependent branching ratios. As a test case a 2D BWR fuel assembly was modelled by first running a burnup calculation followed by a decay calculation. The following source term components were considered when investigating the effect of the studied parameters: total decay heat, photon emission rate and spontaneous fission rate. In general the differences resulting from the use of different parameter variations were small for all three studied source term components. For the decay heat largest absolute relative difference was approximately 0.6 % and for the photon emission rate approximately 1.1 %. For the spontaneous fission rate maximum absolute relative difference of nearly 8 % was observed. For all three components the variation of the depletion zone division resulted in the largest relative differences. Clear differences were also observed for burnup step length and DBRC variations. The use of unresolved resonance probability table sampling and energy dependent branching ratios had an insignificant effect on the studied source term components.

scholarly journals Tailoring the Geometry of Bottom-Up Nanowires: Application to High Efficiency Single Photon Sources

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1201
Author(s):  
Dan Dalacu ◽  
Philip J. Poole ◽  
Robin L. Williams
Keyword(s):  
Quantum Dot ◽  
High Efficiency ◽  
Emission Rate ◽  
Single Photon ◽  
Collection Efficiency ◽  
Photon Emission ◽  
Device Performance ◽  
Bottom Up ◽  
Selective Area ◽  
Photon Generation

For nanowire-based sources of non-classical light, the rate at which photons are generated and the ability to efficiently collect them are determined by the nanowire geometry. Using selective-area vapour-liquid-solid epitaxy, we show how it is possible to control the nanowire geometry and tailor it to optimise device performance. High efficiency single photon generation with negligible multi-photon emission is demonstrated using a quantum dot embedded in a nanowire having a geometry tailored to optimise both collection efficiency and emission rate.

scholarly journals Decay heat power of spent nuclear fuel of power reactors with high burnup at long-term storage

2017 ◽  
Vol 153 ◽  
pp. 07035 ◽  
Author(s):  
Mikhail Ternovykh ◽  
Georgy Tikhomirov ◽  
Ivan Saldikov ◽  
Alexander Gerasimov
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Heat Power ◽  
Decay Heat ◽  
Long Term Storage ◽  
High Burnup ◽  
Term Storage

scholarly journals Prediction of the maximum temperature inside container with spent nuclear fuel

2018 ◽  
pp. 31-35
Author(s):  
S. Alyokhina ◽  
О. Dybach ◽  
A. Kostikov ◽  
D. Dimitriieva
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Maximum Temperature ◽  
Storage Facility ◽  
Storage Container ◽  
Atmospheric Air ◽  
Decay Heat ◽  
Fuel Storage ◽  
Maximum Temperatures ◽  
Cooling Air

The definition of the thermal state of containers with spent nuclear fuel is important part of the ensuring of its safe storage during all period of storage facility operation. The this work all investigations are carried out for the storage containers of spent nuclear fuel of WWER-1000 reactors, which are operated in the Dry Spent Nuclear Fuel Storage Facility in Zaporizhska NPP. The analysis of existing investigations in the world nuclear engineering science concerning to the prediction of maximum temperatures in spent nuclear fuel storage container is carried out. The absence of studies in this field is detected and the necessity of the dependence for the maximum temperature in the storage container and temperature of cooling air on the exit of ventilation duct from variated temperatures of atmospheric air and decay heat formulation is pointed out. With usage of numerical simulation by solving of the conjugate heat transfer problems, the dependence of maximum temperatures in storage container with spent nuclear fuel from atmospheric temperature and decay heat is detected. The verification of used calculation method by comparison of measured air temperature on exit of ventilation channels and calculated temperature of cooling air was carried out. By regression analysis of numerical results of studies the dependence of ventilation air temperature from the temperature of atmospheric air and the decay heat of spent nuclear fuel was formulated. For the obtained dependence the statistical analysis was carried out and confidence interval with 95% of confidence is calculated. The obtained dependences are expediently to use under maximum temperature level estimation at specified operation conditions of spent nuclear fuel storage containers and for the control of correctness of thermal monitoring system work.

scholarly journals Modeling of decay heat removal from CONSTOR RBMK-1500 casks during long-term storage of spent nuclear fuel

Energy ◽  
2019 ◽  
Vol 170 ◽  
pp. 978-985 ◽  
Author(s):  
R. Poškas ◽  
V. Šimonis ◽  
H. Jouhara ◽  
P. Poškas
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Heat Removal ◽  
Decay Heat ◽  
Long Term Storage ◽  
Term Storage

scholarly journals Thermal Excitation Control over Photon Emission Rate of CdSe Nanocrystals

Nano Letters ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 2322-2328
Author(s):  
Benjamin T. Diroll ◽  
Richard D. Schaller
Keyword(s):  
Emission Rate ◽  
Photon Emission ◽  
Cdse Nanocrystals ◽  
Thermal Excitation ◽  
Excitation Control

Resonant photon emission during relative sliding of two dielectric plates

2020 ◽  
Vol 35 (03) ◽  
pp. 2040011 ◽  
Author(s):  
Aleksandr Volokitin
Keyword(s):  
Heat Generation ◽  
Doppler Effect ◽  
Radiative Heat ◽  
Emission Rate ◽  
Photon Emission ◽  
Frequency Range ◽  
Surface Phonon ◽  
Photon Tunneling ◽  
Plasmon Polaritons ◽  
Different Origin

The effect of resonances in the photon emission rate in radiative heat generation and transfer, and Casimir friction at the relative sliding of two plates of polar dielectrics is studied. Resonances are of a different origin in the frequency range of the normal (NED) and anomalous (AED) Doppler effect. In the NED domain, resonances are associated with resonant photon tunneling between surface phonon/plasmon polaritons. In the AED domain resonances are associated with the instantaneous generation of excitations in both plates. While in the NED domain the resonances are finite, in the ADE domain singular resonances are possible even in the presence of dissipation in the system.

Air Cooling Temperature Analysis of Spent Fuel

2005 ◽  
Author(s):  
A. L. Laursen ◽  
F. J. Moody ◽  
J. C. Law
Keyword(s):  
Nuclear Reactor ◽  
Spent Nuclear Fuel ◽  
Natural Circulation ◽  
Maximum Temperature ◽  
Air Cooling ◽  
Spent Fuel ◽  
Decay Heat ◽  
Spent Fuel Pool ◽  
Large Water ◽  
The Relationship

Spent nuclear fuel is currently being stored at nuclear reactor sites. The spent fuel removed from the reactor is first placed in a large water pool to remove the initial decay heat. After several years, when the decay heat has dropped below a set level, the fuel is moved into concrete storage casks where natural circulation continues the cooling process. The purpose of this report is to predict, using a simplified analysis, how hot the fuel rods get when cooled by air in the cask. The increase in temperature and the decrease in density cause a chimney effect in the cask. This paper presents an analytical method of obtaining maximum fuel clad temperature in the cask. A non-dimensional model is derived, which is used to calculate the entrance and exit air velocities of the cask. The relationship between these velocities and the temperature used to obtain the maximum fuel clad temperature. A numerical scheme used to predict the maximum temperature is presented here and the results are compared to the analytical model. Both methods yielded corroborating results for fuel placed in the casks after spending similar amounts of time in a spent fuel pool.

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