Reaction rates in fissile material

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Beam neutron energy optimization for boron neutron capture therapy using Monte Carlo method

In last two decades the optimal neutron energy for the treatment of deep seated tumors in boron neutron capture therapy in view of neutron physics and chemical compounds of boron carrier has been under thorough study. Although neutron absorption cross section of boron is high (3836b), the treatment of deep seated tumors such as gliobelastoma multiform (GBM) requires beam of neutrons of higher energy that can penetrate deeply into the brain and thermalize in the proximity of the tumor. Dosage from recoil proton associated with fast neutrons however poses some constraints on maximum neutron energy that can be used in the treatment. For this reason neutrons in the epithermal energy range of 10eV-10keV are generally to be the most appropriate. The simulation carried out by Monte Carlo methods using MCBNCT and MCNP4C codes along with the cross section library in 290 groups extracted from ENDF/B6 main library. The optimal neutron energy for deep seated tumors depends on the size and depth of tumor. Our estimated optimized energy for the tumor of 5cm wide and 1-2cm thick stands at 5cm depth is in the range of 3-5ke

Molybdenum transmutation via

99mTc is the usual medical isotope for imaging in nuclear medicine. The use of accelerators to produce 99Mo is an alternative to nuclear reactors. Here, the neutron production from a new neutron source is investigated to achieve a proper production yield. The induced neutron was simulated from 30 MeV protons on a beryllium target. The Adiabatic Resonance Crossing (ARC) method was evaluated using lead and bismuth moderators, and lead(II) fluoride reflector around a moderator region. The flux and energy of the aggregated neutrons within different regions of the proposed activator were estimated by the MCNPX code. The epithermal flux in the reflector region was greater than that in the moderator region, since the maximum amount was estimated to be $6.00\text{E}+11\ \text{n/cm}^{2}\text{/s}$ when the bismuth moderator was employed. The outcomes demonstrated that the production yield of 99Mo improved using the bismuth material, whereas the 98Mo sample at a distance $z = -38\ \text{cm}$ from the target showed a greater amount by 5.03E + 5 MBq through a 0.1 cm sample thickness. When the sample was positioned in the reflector region, the obtained yield increased taking advantage by the more accumulated flux in the epithermal range. The ARC method can replace conventional reactor-based prototypes of the 99Mo-99mTc generator, or complement them, because it is safe and more accessible

Magnetohydrodynamic (MHD) stability of wendelstein7-X reactor with resistive wall (RWMs)

Plasma stability is the biggest challenge facing the nuclear fusion industry. One of the best methods of stability study is magnetohydrodynamic (MHD) equations, which has two linear and nonlinear states. Usually linear stability analysis is used to describe the MHD state, which is obtained by linearizing nonlinear equations. The reactor under study is the W7-X reactor, which is an optimal example of a stellaratoric system. The question raised in this research is how to create suitable conditions for the formation of plasma and heat transfer produced by the melting reaction. Many efforts have been made in this direction, but still the record holder for plasma state maintenance belongs to the international ITER project and around 1000. However, IPP researchers at the Max Planck Institute in Germany (maker of the W7-X reactor) predicted that by 2020 they would produce a pulse of 30 minutes. The numerical method is used to investigate the stability of the reactor. In this paper, boundary conditions were expressed in terms of resistance wall. With the help of the mathematical Matlab software, magnetic field values ​​were obtained from experimental reports extracted from the Max Planck Institute for various values ​​of β. From the values ​​obtained, it was concluded that the appropriate field value is β = 5 according to the ideal MagnetoHydroDynamic state and the interval defined by the Max Planck Institute

Comparison of Different Packaging Materials and Solutions on a Cost Basis for Volvo Logistic Corporation

The basic problem that this thesis addresses was to compare different packaging materials for Volvo Logistics Corporation (VLC) from a cost perspective. Since this thesis was conducted for VLC only, their main packaging solutions were defined and categorized by size. With this, various materials in each size category were studied, analyzed and compared from different aspects. These aspects ranged from volume efficiency to ergonomics and cleanliness. Some of these aspects were easy to quantify and calculate while others, such as ergonomics and cleanliness, had to be evaluated qualitatively. The outcome of this research was a financial/comparative model, which allows users to choose the packaging solution with the lowest possible cost or the packaging solution that best meets their requirements. The conclusion is that technically the best packaging solution is not necessarily the cheapest because of the indirect logistical costs in addition to the packaging price.Uppsatsnivå:

Presenting and simulating an innovative model of liver phantom and applying two methods for dosimetry of it in neutron radiation therapy

AimA new model of liver phantom is defined, then this model is simulated by MCNPX code for dosimetry in neutron radiation therapy. Additionally, an analytical method is applied based on neutrons collisions and mathematical equations to estimate absorbed doses. Finally, the results obtained from two methods are compared to each other to justify the approach.BackgroundThe course of treatment by neutron radiation can be implemented to treat cancerous tissues, although this method has not yet been widespread.The MIRD and the Stylized Family Phantom were the first anthropomorphic phantoms, although the representation of internal organs was quite crude in them. At present, a water phantom is usually used for clinical dosimetry.Materials and methodsEach of the materials in an adult liver tissue including water and some organic compounds is decomposed into its constituent elements based on mass percentage and density of every element. Then, the accurate mass of every decomposed material of human liver tissue is correlated to masses of the phantom components.ResultsThe absorbed doses are computed by MCNPX simulation and analytical method in all components and different layers of this phantom.ConclusionsWithin neutron energy range of 0.001[[ce:hsp sp="0.25"/]]eV–15[[ce:hsp sp="0.25"/]]MeV, the calculated doses by MCNPX code are approximately similar to results obtained by analytical method, and the derived graphs of both methods approve one another. It is also concluded that through increasing the incident neutron energy, water receives the largest amounts of absorbed doses, and carbon, nitrogen and sulfur receive correspondingly less amounts, respectively