Nuclear Engineering and Radiation Science Faculty Research & Creative Works
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Recent documents in Nuclear Engineering and Radiation Science Faculty Research & Creative Works
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Fri, 17 May 2024 03:06:59 PDT
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Cyber Agent on the World Wide Web
https://scholarsmine.mst.edu/nuclear_facwork/567
https://scholarsmine.mst.edu/nuclear_facwork/567
Wed, 15 May 2024 11:36:05 PDT
The World Wide Web has brought the information from a distributed environment into a global information universe. As users keep on surfing the Web and adding their bookmarks, it is increasingly difficult for them to find their desired information even though there are many search tools available. In this paper, a smart engineering system called Cyber Agent is proposed to help users search and organize the information. It contains two major subsystems, namely, WebTracer and WebOrganizer. They adapt their behavior dynamically according to the environment and the special preferences of each individual. WebTracer is the wavefront of the Cyber Agent while WebOrganizer is the brain of the Cyber Agent.
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HyoungKoo Lee et al.

Photon Dose Equivalent Rate from a Cylindrical Source using a Point Kernel Technique
https://scholarsmine.mst.edu/nuclear_facwork/566
https://scholarsmine.mst.edu/nuclear_facwork/566
Wed, 15 May 2024 11:36:04 PDT
The photon dose equivalent rate as a function of distance from a cylindrical source was calculated using a point kernel technique in the energy range 0.35 MeV. Buildup factors for a single medium were those given by the geometric progression formula. The buildup factor for the whole geometry was considered as that from a multilayer shield represented by the Broder formula with two corrections applied to it: the first for finite shield and the second for the contribution of the last layer as given by Kitazume. The accuracy of this algorithm was tested by performing a MCNP (General Purpose Monte Carlo Code for Neutral Particle Transport) calculation for the same source and comparing the two sets of results. The conclusion is that the point kernel technique, with the corrections mentioned above included, gives results that agree with those obtained by using MCNP in most cases to within 10%. Therefore, the method presented here is adequate for performing a dose equivalent rate computation as the effort for using it is much smaller than that needed using the MCNP code.
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Nicholas Tsoulfanidis et al.

Spherical Harmonics  Finite Element Treatment of Neutron Transport in Cylindrical Geometry
https://scholarsmine.mst.edu/nuclear_facwork/565
https://scholarsmine.mst.edu/nuclear_facwork/565
Wed, 15 May 2024 11:36:03 PDT
A variational spherical harmonics (DPN) method is used in conjunction with the finite element method to solve the transport of neutron beams. The method is developed for finite axisymmetric cylindrical geometry. In this model, the angular distribution along the path of neutron travel is separated into two subranges of the forward and the backward moving particles. The system of the model equations is cast in terms of an even and an odd vector analogue to the evenparity transport technique. The finite element method is applied in space to solve the resulting coupled system of equations. A sourcefree cylinder with specified incident flux on the z = 0 surface is considered in this study. The model is based on the DP1 and DP3 orders of expansion. The study demonstrates the advantages of the DPN method in accounting for the discontinuity of the angular flux in the direction of particles with no approximation. Results for the scalar flux are presented in isodose curve (contour) form for homogeneous and nonhomogeneous media with different absorbing and purely scattering media. Numerical results compared favorably with those obtained by the exact solutions. © 1997 Elsevier Science Ltd. All rights reserved.
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Hatem Khouaja et al.

Cadmium Cutoff Energy for MCNP Modeling of Dosimetry Reactions
https://scholarsmine.mst.edu/nuclear_facwork/564
https://scholarsmine.mst.edu/nuclear_facwork/564
Wed, 15 May 2024 11:36:03 PDT
The MCNP code modeling of reactor cavity dosimetry reactions to validate the computed neutron flux hitting the pressure vessel of a pressurized water reactor (PWR) requires the choice of an appropriate cadmium cutoff energy. Since the neutron spectrum is harder in the cavity than in the core, the same cadmium cutoff energy may not be universally applied. The correct cutoff energy for the cavity of a PWR was computed by using MCNP4a and a representative cavity spectrum. Four cadmiumcovered foil reactions were analyzed, and the appropriate energy cutoff was determined to be approximately 0.6 eV for approximately 0.5mmthick cadmium covers.
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Peter G. Laky et al.

DESIGN of a TARGET and MODERATOR at the LOS ALAMOS SPALLATION RADIATION EFFECTS FACILITY (LASREF) as a NEUTRON SOURCE for FUSION REACTOR MATERIALS DEVELOPMENT
https://scholarsmine.mst.edu/nuclear_facwork/563
https://scholarsmine.mst.edu/nuclear_facwork/563
Wed, 15 May 2024 11:36:02 PDT
The LASREF facility is located in the beam stop area at LAMPF. The neutron spectrum is fissionlike with the addition of a 3% to 5% component with E > 20 MeV. The present study evaluates the limits on geometry and material selection that will maximize the neutron flux. MCNP and LAHET were used to predict the neutron flux and energy spectru/n for a variety of geometries. The problem considers 760 MeV protons incident on tungsten. The resulting neutrons are multiplied in uranium through (n,xn) reactions. Calculations show that a neutron flux greater than 1019n/m2/s is achievable. The helium to dpa ratio and the transmutation product generation are calculated. These results are compared to expectations for the proposed DEMO fusion reactor and to FFTF.
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Phillip D. Ferguson et al.

Neutron Fluence at the Pressure Vessel of a Pressurized Water Reactor Determined by the MCNP Code
https://scholarsmine.mst.edu/nuclear_facwork/562
https://scholarsmine.mst.edu/nuclear_facwork/562
Wed, 15 May 2024 11:36:01 PDT
Pressure vessel fluence and reaction rates for dosimetry foils in the cavity surrounding the pressure vessel of a pressurized water reactor were determined with a Monte Carlo calculation using the MCNP code. Source neutrons were sampled from a position probability distribution derived from the utilityprovided normalized assembly segment power output. The MCNP model was based on oneeighth core symmetry. Source segment spatial biasing, energy cutoff, spatial importance functions, and weight windows were employed as variance reduction techniques. Computed reaction rates were compared with measured ones and in one case to discrete ordinates transport code calculations. Computed reaction rates matched the measured ones within ±10% for 21 of 33 cases and within ±15% for 26 of 33 cases. Neutron flux and fluence >0.1111 and 1 MeV at the pressure vessel location were computed to <10% statistical uncertainty. The estimated maximum fluence per cycle was found to be of the order of 1017 n/cm2.
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Peter G. Laky et al.

Exposure Buildup Factors of UO2 using the Monte Carlo Method
https://scholarsmine.mst.edu/nuclear_facwork/561
https://scholarsmine.mst.edu/nuclear_facwork/561
Wed, 15 May 2024 11:36:00 PDT
When the gamma dose rate around an irradiated nuclear reactor fuel element is calculated, it is important to know the attenuating characteristics of the fuel element itself, one of them being the buildup factor. Exposure buildup factors of uranium dioxide (UO2) for ten gammaray energies (0.050 to 10.0 MeV) have been computed for ten material thicknesses (0.5 to 10.0 mean free paths) using the MCNP code. The accuracy of the MCNP model was checked by computing the buildup factors of oxygen and uranium and comparing these results with the data given in the literature for these elements. The results indicate that the UO2 exposure buildup factors, for the energies and distances studied, are close to those of uranium.
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Ahmet Bozkurt et al.

Modeling GammaRay Dose Rate from a Spent Pressurized Water Reactor Fuel Assembly
https://scholarsmine.mst.edu/nuclear_facwork/560
https://scholarsmine.mst.edu/nuclear_facwork/560
Wed, 15 May 2024 11:35:59 PDT
Gammaray dose rate distribution around a pressurized water reactor spentfuel assembly is studied using the Monte Carlo Nparticle transport code (MCNP) version 4a. A detailed rodbyrod modeling of the assembly is utilized, showing explicitly the fuel, cladding, control rod channels, and the instrumentation tube. A cylindrically distributed source of gamma rays, within every fuel rod, is considered with a sevengroup energy spectrum. Dose rates are obtained by tallying the gamma rays at several axial and radial positions outside the assembly. The results indicate that the radial distribution of the dose rate can be represented by a power relationship of the form rn, where r is the radial distance from the assembly center. Another important conclusion from this study is that the dose rate close to the assembly surface is overestimated if a homogeneous assembly model is used.
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Ahmet Bozkurt et al.

ComputerBased Teaching and Assessment in Topics on Basic Physics
https://scholarsmine.mst.edu/nuclear_facwork/558
https://scholarsmine.mst.edu/nuclear_facwork/558
Wed, 15 May 2024 11:35:58 PDT
This paper describes an experience in computerbased teaching and assessment in three topics in basic physics. A module is developed for each topic using the Authorware courseware authoring tool. The first module is on fundamental particles, the second on binding energy, and the third on atom density calculation. These modules are also installed on the web. Each module has four components: 1) definition, 2) example, 3) review questions, and 4) quiz. Students can see their performance on review questions interactively and have the option to repeat them, and receive online feedback on their score. Similarly, their performance on a quiz is evaluated online and feedback is provided to them. In addition, their score on each quiz as well as the time they spent taking the quiz are sent back to the instructor and stored in a permanent file. The courseware provides an overall assessment, in graphical format, of the average performance of all students who took a quiz, as well as each individual student's performance. These modules are taught as supplementary part s of a course in Fundamentals of Nuclear Engineering at the University of MissouriRolla Nuclear Engineering Department. The experience has been positive with more than 80% of the students supporting the value of the interactive and selfpace learning of these modules.
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Shahla Keyvan et al.

Benefits of the Undergraduate Research Experience
https://scholarsmine.mst.edu/nuclear_facwork/559
https://scholarsmine.mst.edu/nuclear_facwork/559
Wed, 15 May 2024 11:35:58 PDT
The role of the University should be directed towards cultivating and increasing the ability of students to think. The ability to think is more important than the simple transfer of knowledge. The student's ability to think will increase if research will be used as an active component of teaching.
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Nicholas Tsoulfanidis

Valorization of Spent ZnC Battery and Construction and Demolition Waste (CDW): Fabrication and Characterization of Geopolymer Composites for Radiation Shielding Applications
https://scholarsmine.mst.edu/nuclear_facwork/557
https://scholarsmine.mst.edu/nuclear_facwork/557
Wed, 17 Apr 2024 10:21:46 PDT
There is a Serious Threat of Pollution Due to the High Waste of Energy and Materials Worldwide that Needs to Be Decreased. One Way is to Reduce Waste or Use Them in Secondary Processes. New EcoFriendly Geopolymer Binders Were Fabricated using Metakaolin, CDW, and Battery Waste (BW) Powders as Starting Materials and a Mixture of Potassium Silicate and Sodium Hydroxide as Activation Solutions. 5 Formulations with BW Powder Replacements Ranging from 5 to 40 Wt% Were Prepared and Subjected to Heat Curing at 80 °C for 24 H. the Effect of ZnC Battery Waste Content on the Phase Composition, Densification, Microstructure, Mechanical, and Gamma Shielding Properties of the Obtained Geopolymer Composites Was Investigated. the Results Revealed that Incorporating Battery Waste Reduced the Density and Mechanical Strength of the Geopolymer Composites. Additionally, Microstructural Analysis Indicated that Synthesized Geopolymers Consisted of Unreacted CDW and BW Particles Embedded in a Geopolymer Matrix with a Low Degree of Compactness. the Effect of BW Replacement on the Shielding Capacity Was Also Evaluated Experimentally and Theoretically. the Gamma Transmission Experiments Proved that the Addition of BW Caused a Reduction in the Radiation Shielding Ability of the Composites When They Were Exposed to 137Cs and 60Co GammaRay Sources. Finally, the Variation of the Main Attenuation Parameters (MAC, HVL, EBF, and EABF) with Photon Energy Was Also Obtained Theoretically. the Outcomes of This Investigation Can Provide a Basis for the Design of New CDWBased Geopolymers for Radiation Shielding Applications in the Context of a Circular Economy.
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Raul Florez et al.

Polarization Of ComptonScattered Prompt GammaRay Technique For HEU Detection At 186 KeV
https://scholarsmine.mst.edu/nuclear_facwork/556
https://scholarsmine.mst.edu/nuclear_facwork/556
Fri, 05 Apr 2024 07:00:08 PDT
Prompt GammaRay Polarization Is A Practical Method For Detecting Highly Enriched Uranium (HEU) In Concealed Sources. It Also Provides Information On Their Geometry, Magnetic Fields, And Radiation Mechanisms. However, Prompt GammaRay Polarization Measurements Have Rarely Been Applied In Nuclear Nonproliferation Areas To Detect HEU. In This Study, The Feasibility Of Detecting The Characteristic Energy Peak Of 186 KeV, Which Is Associated With The Asymmetry Of The Activation Mechanism And The Detection Of EnergyDependent Polarization From Concealed HEU Sources, Was Evaluated Using The Compton Scattering Approach. A Monte Carlo NParticle Transport Code Simulation Was Used To Realize The Activation Mechanism Of HEU Via Two 1.4Mm Strips Of Converter Material [I.e., Cesium Lead Tribromide (CsPbBr3)], Transported By Secondary Scattered Gamma Rays During The ThreeStage Process Of Compton Scattering, Polarization, And Detection. This Paper Presents The Mathematical Model, The Physics Of Compton Scattering, And The Polarization Mechanism For The Detection Technique. In This Case, The Physics Is Relevant To Both Processes In Which The Emitted Secondary Scattered Gamma Rays Undergo Initial Orthogonal Polarization. Specifically, To Meet The Objective Of Testing The Technical Protocol For The Enhanced Detection Of Energy Peaks Associated With HEU, Particularly 186 KeV, Simulations Were Conducted To Quantify The HEU Volume And Neutron Source Strength In The MCNP Data Card To Perform Error Analysis. The Detector System Had The Potential To Acquire Good Resolved Photopeak With A 4.5% Relative Error Or Less, With A 1 Ci Source Activity, And A PeakToBackground Ratio Of 1.15. This Resolution Took 163 S For HighPurity Germanium Detection, Which Is Comparable To Current Methods Used For Material Detection Placed Within 100 To 900 S To Completion. The Small Error Difference Was Due To The Attributes Of The Phenomenal Enhancement Properties Of Cesium Tribromide And Polarimetry. The Identified Photo Peaks Included KShell XRays From 235U, 61 KeV From Fission, 511KeV Annihilation, And The Peak Of Interest At 186 KeV. The Result From Spectral Analyses Showed Clear Signatures Related To Pure And Adulterated HEU. HEU Detection With The Low Neutron Yield And The Easiness Of Shielding The Yield Of The HEU Sample Showed That The HEU Characterization Was Feasible When Shielded, With The Highest Success Rate Under Both Enhancement Approaches. The Optimization And ScaleUp Of This Technique Are Expected To Enhance Its Applications In A LargeScale HEU Detection Design.
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Athanas Mutiso et al.

Simulation Study Of Electron Beam Optics For A Distributed XRay Source Toward Stationary CT Architecture
https://scholarsmine.mst.edu/nuclear_facwork/555
https://scholarsmine.mst.edu/nuclear_facwork/555
Wed, 27 Mar 2024 08:45:23 PDT
For computed tomography (CT) imaging to be considered "real time", one set of tomographic projections are to be acquired in less than 30 ms. Current conventional CT systems are limited to approximately 300 ms because of mechanical and material limitations. To bypass the mechanical limitations of a conventional gantry system, there is an open design challenge to develop a distributed Xray source that is tightly packed and bright. The work presented here reports a design for a distributed Xray source based on a rotating cylindrical anode. In particular, this work focuses on designing the electron beam optics for said Xray source and refining these optics via multiphysics simulation studies. We designed these studies to investigate the electron beam behavior for switching, steering, and focusing. We demonstrated that the highenergy electron beam could be turned off and on via the gridswitching technique, could be steered, and could be dynamically focused for distinct positions along the cylindrical anode. We also report the optimal set of parameters that result in the desired electronic focal spot size (1 mm x 7 mm) and shape at each source position for our system.
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Jordan Fox et al.

TwoGroup DriftFlux Model for Dispersed GasLiquid Flow in LargeDiameter Pipes
https://scholarsmine.mst.edu/nuclear_facwork/554
https://scholarsmine.mst.edu/nuclear_facwork/554
Thu, 26 Oct 2023 10:50:12 PDT
Interfacial Heat and Mass Transfer Are Prevalent in Industrial Processes. the Interfacial Transfer Rate Can Be Obtained by the Product of their Fluxes and Interfacial Area Concentration (IAC) Calculated by the Interfacial Area Transport Equation (IATE). Bubbles Show Different Behavior According to their Sizes. Hence, Bubbles Are Classified into Two Groups. Consequently, TwoGroup IATE is Required Causing to Use of Two Gas Momentum Equations Leading to More Complexity. the Present Study Suggests a New Reliable TwoGroup DriftFlux Modeling to Reduce the Two Gas Momentum Equations to One Gas Mixture Momentum Equation for GasLiquid Flow in LargeDiameter Pipes. the Model is Developed based on the DriftFlux Model Concept and Experimental Data. GroupOne and GroupTwo Distribution Parameters and Drift Velocities Are Validated through Experimental Data. the Results Show that the Proposed TwoGroup DriftFlux Model Can Support the Concept of Drift Velocity from the Bubbly to Beyond the Bubbly Flow and Consistency between the OneGroup and TwoGroup DriftFlux Models. Moreover, SteamWater Data Are Used to Validate the Applicability of the Model in SteamWater Flows Condition. the Developed TwoGroup DriftFlux Model is Indispensable for Reducing the Two Gas Momentum Equations to One Gas Mixture Momentum Equation When TwoGroup IATE is Implemented into ThermalHydraulic Codes to Improve the Prediction Accuracy of IAC.
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Hossein Barati et al.

3D CFD Simulation of a Bubble Column with Internals: Validation of Interfacial Forces and Internal Effects for Local Gas Holdup Predictions
https://scholarsmine.mst.edu/nuclear_facwork/553
https://scholarsmine.mst.edu/nuclear_facwork/553
Mon, 16 Oct 2023 11:05:14 PDT
CFD Models (Turbulent Models and Interfacial Forces) Incorporated with the Population Balance Model (PBM) Have Been Validated, Azimuthally, with the GammaRayComputed Tomography (CT) Results to Address the Effect of the Presence of Internals with Different Arrangements and Diameters. the Superficial Gas Velocity Applied Was Varied from 0.05 to 0.45 M/s. the Results Exhibit the Capability to Predict the Hydrodynamics of the Bubble Column, Further Incorporating the Population Balance Model and Promoting the Prediction of Simulation in High Superficial Gas Velocity. the Effect of Internals Revealed that the Gas Holdup Was Significantly Enhanced in the Bubble Column's Wall Region, While the Gas Holdup Was Increased Remarkably in the Center and the Wall Regions of the Bubble Column Equipped by Internals of 1 In. Diameter More Than in Internals of 0.5 In. However, Internals with a Hexagonal Arrangement Increase the Gas Holdup in the Central Region and Less in the Wall Than in the Circular Arrangement.
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Hayder AlNaseri et al.

CementBased Materials With SolidGel Phase Change Materials For Improving Energy Efficiency Of Building Envelope
https://scholarsmine.mst.edu/nuclear_facwork/552
https://scholarsmine.mst.edu/nuclear_facwork/552
Fri, 22 Sep 2023 13:11:37 PDT
This paper evaluated the cementbased materials incorporated with novel solidgel phase change materials (PCMs) for improving the energy efficiency of building envelopes. This novel PCM is formstable, which will not leak as solidliquid PCMs do and not need encapsulation, and it features high energystorage capacity. Experimental results showed that the thermal properties of cementbased materials were improved as the increase of PCM content. A 30% replacement of sand by volume with PCM can increase the latent heat of the mixture from around 0 to 7 J/g and decrease the thermal conductivity of PCM mortar based on the generalized selfconsistent (GSC) model by about 20%. However, the workability and mechanical properties were compromised. The simulation results indicated that 30% PCMincorporated walls can contribute to 5% energy saving for cooling in a whole year and 12% reduction in peak cooling load compared with the reference without PCM. The proposed PCM composite offers a promising avenue to achieve energyefficient building envelopes.
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Zhuo Liu et al.

Defect Generation Mechanisms In Silica Under Intense Electronic Excitation By Ion Beams Below 100 K: Interplay Between Radiative Emissions
https://scholarsmine.mst.edu/nuclear_facwork/551
https://scholarsmine.mst.edu/nuclear_facwork/551
Thu, 17 Aug 2023 09:33:47 PDT
Ionbeam effects on bulk silica at low temperature have been studied with the aim of understanding the routes and mechanisms leading from the initial generation of free carriers and selftrapped excitons (STEs) to the production of two stable defect structures in irradiated silica, nonbridging oxygen hole centers (NBOHCs) and oxygen deficient centers (ODCs). Ion beam induced luminescence (ionoluminescence, IL) spectra were obtained using 3 MeV H, 3.5 MeV He, 19 MeV Si, and 19 MeV Cl ions and a range of cryogenic irradiation temperatures from 30 to 100 K. The kinetic behavior of three emission bands centered at 1.9 eV (assigned to NBOHCs), 2.1 eV (assigned to the intrinsic decay of STEs), and 2.7 eV (assigned to ODCs) reveal the physical origin of these emissions under intense electronic excitation. The creation of NBOHCs is governed by a purely electronic mechanism. The kinetics curve of the NBOHC band shows two main contributions: an instantaneous (beamon) contribution, followed by a slower fluence and temperaturedependent process correlated with the concentration of STEs. The beamon contribution is proportional to deposited ionization energy. The growth of the ODC band is linear in fluence up to around 2 x 1012 cm−2. The growth rate is independent of temperature but proportional to the number of radiationinduced oxygen vacancies per ion, showing, unambiguously, that the 2.7 eV emission can be associated with ODCs created in an excited state.
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M. L. Crespillo et al.

Dose Rates For Several Organs In A Human From Contaminated Soil And Hot Particles Using The Qad Computer Code
https://scholarsmine.mst.edu/nuclear_facwork/550
https://scholarsmine.mst.edu/nuclear_facwork/550
Fri, 04 Aug 2023 13:10:36 PDT
Dose rates from contaminated soil and hot particles have been calculated for several organs of a reference human. The calculation was performed using the computer code QADCGGP, a point kernel code employing combinatorial geometry for the representation of the human phantom. QAD uses buildup factors based on the geometric progression form, a buildup factor representation adopted by the American Nuclear Standards Committee. The results indicate that QAD is a powerful and easytorun code that produces useful results for practicing health physicists. © 1991 Health Physics Society Pergamon Press plc.
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Nicholas Tsoulfanidis et al.

Radioactive Waste Management
https://scholarsmine.mst.edu/nuclear_facwork/548
https://scholarsmine.mst.edu/nuclear_facwork/548
Fri, 04 Aug 2023 13:10:35 PDT
The management of radioactive waste is a very important part of the nuclear industry. The future of the nuclear power industry depends to a large extent on the successful solution of the perceived or real problems associated with the disposal of both lowlevel waste (LLW) and highlevel waste (HLW). All the activities surrounding the management of radioactive waste are reviewed. The federal government and the individual states are working toward the implementation of the Nuclear Waste Policy Act and the LowLevel Waste PolicyAct. The two congressional acts are reviewed and progress made as of early 1990 is presented. Spentfuel storage and transportation are discussed in detail as are the concepts of repositories for HLW. The status of state compacts for LLW is also discussed. Finally, activities related to the decommissioning of nuclear facilities are also described.
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Nicholas Tsoulfanidis et al.

Sensitivity Analysis Of Thermalhydraulic Parameters And Probability Estimation Of Boiling Transition In A Standard BWR/6
https://scholarsmine.mst.edu/nuclear_facwork/549
https://scholarsmine.mst.edu/nuclear_facwork/549
Fri, 04 Aug 2023 13:10:35 PDT
A model correlating the minimum critical power ratio (MCPR) of standardized boiling water reactors (BWRs) to a set of thermalhydraulic variables in parameter space is developed. A statistical approach with fractional factorial sampling along with response surface methodology and orthogonal central composite design are employed. The COBRAII computer code, after modifications to include MCPR calculation, is used to simulate the thermal hydraulics of the BWR/6. The sensitivity is obtained by differentiating a quadratic equation that represents the state of the system with respect to its constituent variables. Taking this correlation as a joint multivariable probability distribution function and using crude Monte Carlo integration techniques, the probability of boiling transition during normal operation in a standardized BWR/6 is estimated. The result agrees very well with data available in open literature.
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Smaeil M. Aceil et al.