分类： 物理学 >> 核物理学 提交时间： 2016-09-19
摘要： Spent nuclear fuel (SNF) antineutrino flux is an important source of uncertainties for a reactor neutrino flux prediction. However, if one want to determine the contribution of spent fuel, many data are needed, such as the amount of spent fuel in the pool, the time after discharged from the reactor core, the burnup of each assembly, and the antineutrino spectrum of the isotopes in the spend fuel. A method to calculate the contribution of SNF is proposed in this study. In this method, reactor simulation code verified by experiment have been used to simulate the fuel depletion by taking into account more than 2000 isotopes and fission products, the quantity of SNF in each six spend fuel pool, and the antineutrino spectrum of SNF varying with time after SNF discharged from core. Results show that the contribution of SNF to the total antineutrino flux is about 0.26%~0.34%, and the shutdown impact is about 20%. The SNF spectrum would distort the softer part of antineutrino spectra, and the maximum contribution from SNF is about 3.0%, but there is 18\% difference between line evaluate method and under evaluate method. In addition, non-equilibrium effects are also discussed, and the results are compatible with theirs considering the uncertainties.
分类： 物理学 >> 核物理学 提交时间： 2024-05-17
Yan Zhang
Hao-Ran Zhang
Ren-Bo Wang
Ming-Yu Li
Rui Chen
Hai-Tao Wang
Xiang-Ting Meng
Shu-Min Zhou
Bin Tang
摘要： A passive neutron multiplicity measurement device, FH-NCM/S1, based on field-programmable gate arrays(FPGAs), is developed specifically for measuring the mass of plutonium-240 (240Pu) in mixed oxide fuel. FHNCM/S1 adopts an integrated approach, combining the shift-register analysis mode with the pulse-positiontimestamp mode using an FPGA. The optimal effective length of the 3He neutron detector was determined tobe 30 cm, and the thickness of the graphite reflector was ascertained to be 15 cm through MCNP simulations.After fabricating the device, calibration measurements were performed using a 252Cf neutron source; a detectionefficiency of 43.07% and detector die-away time of 55.79 μs were observed. Nine samples of plutoniumoxide were measured under identical conditions using the FH-NCM/S1 in shift-register analysis mode and aplutonium-waste multiplicity counter. The obtained double rates underwent corrections for detection efficiency(ε) and double gate fraction (f d), resulting in corrected double rates (Dc), which were used to validate the accuracyof the shift-register analysis mode. Furthermore, the device exhibited fluctuations in the measurementresults, and within a single 20-s measurement, these fluctuations remained below 10%. After 30 cycles, therelative error in the mass of 240Pu was less than 5%. Finally, correlation calculations confirmed the robustconsistency of both measurement modes. This study holds specific significance for the subsequent design anddevelopment of neutron multiplicity devices.
分类： 核科学技术 >> 乏燃料后处理技术 提交时间： 2022-05-28
摘要： Nuclearmateriallicenseholdershoulddevelopanuclear materialaccountingmanagementsystemandachievethe closedbalance. Accordingtoregulationsrequirements, nuclear materialaccountancyimplementationisbasedonphysical inventoryandmaterialmeasurement. Generally, thespentfuel reprocessingplantoperatesuninterrupted, annualthroughput ofnuclearmaterialsishuge, differentmeasurementand analysistechniquesareconfiguredcombingthereprocessing process. Sotheclosedbalanceapproachofnuclearmaterials accountingisagreatchallenge. Inordertoimprovethe accuracyandreliabilityofnuclearmaterial, enhancethe timelinessofabnormaldetection, near-realtimeaccounting prospectofspentfuelreprocessingplantwasresearched. Inthis paper, thecrucialaspectaffectingtheclosedbalanceofnuclear materialswasdiscussed, thefactorssuchasthehead-end receiver-shipperdifference, theon-lineprocessmonitoring accuracy,theapplicabilityoftheinternationaltargetvalueof nuclearmaterialmeasurementuncertainty, andalsothe nuclearmaterialbalancemodelofreprocessingplants. As summarized,proposedsuggestionsandsolutionsfornuclear materialbalanceinspentfuelreprocessingplantwasput forwardontheendofthepaper.
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