Thermal Column Research Articles

A significant review on beam optimization for boron neutron capture therapy

The thermal column at the TRIGA PUSPATI (RTP) research reactor can produce thermal neutron. However, the optimization on the thermal neutron flux produced should be performed to gain a sufficient thermal neutron for boron neutron capture therapy purpose. Thus, the objective of this review is to optimize the thermal neutron flux by designing the collimator with different materials at the thermal column. In order to fulfil the requirement, set by the IAEA standard, the study of BNCT around the world was being reviewed to study the suitable measurement, material, design, and modification for BNCT at the thermal column of TRIGA MARK-II, Malaysia. Initially, the BNCT mechanisms and history was review. Then, this paper review on the design and modifications for BNCT purpose around the world. Based on this review, suitable material and design can be used for the BNCT in Malaysia. Moreover, this paper also reviews the current status of BNCT at the RTP with the measurement of the thermal neutron flux was conducted along the thermal column at 250 kW. The thermal column of RTP was divided into 3 phases (Phase 1, Phase 2 and Phase 3) so that an accurate measurement can be obtained by using gold foil activation method. This value was used as a benchmark for the neutron flux produced from the thermal column. The collimator was designed using different types of materials, and their characteristic towards gamma and neutron flux was investigated. The reviewed demonstrated that the final thermal neutron flux produced was significantly for BNCT purpose. Lastly, this paper recommends the future research can be conducted on BNCT at RTP.

A design on the collimator for boron neutron capture therapy (BNCT) research facility at the thermal column of TRIGA MARK II

The development of the Boron Neutron Capture Therapy (BNCT) facility in Malaysia can be performed at the thermal column of the Malaysia research reactor. TRIGA MARK II is one of the facilities that can provide neutron source for BNCT facility. The specification of neutron flux and the gamma dose rate must consider for the development of the BNCT facility as a safety precaution for this research. Based on previous research, the thermal column identified as a suitable place for BNCT facility. To design the neutron collimator for BNCT purpose, the characterization of material towards thermal neutron flux explored using TLD and Microspec-6 and the collimator design was simulate using Monte Carlo N-Particle (MCNP) software based on the characterize materials in order to produce high thermal neutron flux. The combination of lead, HDPE, 30% borated polyethylene and aluminium as collimator design D1 simulate the highest thermal neutron 1.5770 x 109 neutron.cm−2s−1 and suitable for BNCT research purpose at the thermal column.

A simulation on desired neutron flux for the boron neutron capture therapy (BNCT) purpose by using Monte Carlo N-Particle (MCNPX)

Boron Neutron Capture Therapy (BNCT) is a nuclear application to cure cancer by using the interaction between the boron compound and the slow (thermal and epithermal) neutron beam obtained from the neutron source. The previous feasibility study shows that the thermal column can generate higher thermal neutrons for BNCT application at the TRIGA MARK II reactor. Currently, the BNCT facility is planned to be developed at the thermal column. Thus, to fabricate the nuclear application such as BNCT required several required such as the study of design, material, neutron desired and safety for the application. Therefore, the use of simulation software such as Monte Carlo N-Particle (MCNP) was extensively essential to identify and determine the most convenient design of the BNCT facility with proper safety requirement standard. Besides that, the simulation also useful in terms of identifying good material and best geometry and the uses of simulation can guide to make sure this research achieves the best results. Generally, MCNP function to track the particle over its energy range using the irradiation transport and the neutron flux and the gamma flux produced from the simulation using MCNPX code was consider right if the relative errors contributed was lower than 5%. This research simulates that the uncovered collimator provides high neutron flux and high collimator performance compared to the fully covered collimator. This research is useful in the simulate on the desired neutron from the BNCT facility design at the TRIGA MARK II reactor.

Prompt Fission Gamma-Ray Measurements at UML Research Reactor

Neutron-induced fission of 235U was studied at the thermal column of the UMass Lowell 1 MW Research Reactor. A collimated, 2.25-inch diameter beam of thermal neutrons with the flux of ~5x105 n/cm2/sec induced fission reaction on a plate of low-enriched uranium with the areal density ~25 mg/cm2 of 235U. We have used the prompt fission-neutron tagging method to identify the fission reaction in the off-line analysis. The method employs the pulse-shape discrimination of neutrons and gamma-ray events in stilbene scintillator and enables identification of coincidence events of prompt fission gamma-rays and prompt fission neutrons in coincidence time intervals less than 20-30 ns. The prompt gamma-ray radiation was detected using two co-linear NaI(Tl) detectors. The measured spectra of prompt-fission gamma rays between 150 keV and 6 MeV are presented. The results from these initial measurements demonstrate the feasibility of the experimental method. Future measurements with extended arrays of detectors are planned.

Present Geothermal Characteristics and Influencing Factors in the Xiong’an New Area, North China

The present geothermal characteristics and influencing factors are analyzed to conduct geothermal resource exploration in the Xiong’an New Area. Thermal conductivity data for 100 rock samples are obtained from different wells and a sedimentary strata thermal conductivity column is proposed. From these data, heat flow distribution in the area is mapped using equilibrium temperature logs obtained for 32 wells. The heat flow in this area is found to be 53.3–106.5 mW·m−2 (average: 73 mW·m−2). The uplift heat value in Niutuozhen and Rongcheng uplift is 106.5 and 90 mW·m−2, respectively. The sag heat flow is relatively low and the Baxian sag’s heat flow value is 48.9–61.6 mW·m−2. Thermal conductivity differences among Cenozoic caprock, Proterozoic carbonate reservoirs, and basement rock mainly affects the geothermal distribution. The low and high thermal conductivities of the caprock and thermal reservoir as well as basement, respectively, cause heat flow redistribution in the surface during conduction. Groundwater rises to geothermal reservoirs through heat-controlling faults, causing convective heat transfer and increasing the geothermal reservoir temperature; therefore, high-temperature groundwater accumulates in the shallow uplift areas. The caprock’s thin uplift area exhibits a high geothermal background due to water convergence. Understanding the geothermal characteristics and influencing factors is necessary for understanding the distribution law and factors influencing geothermal resources and guiding geothermal exploration and development in the Xiong’an New Area.

The Thermal Response of Concrete Frame Buildings in Arabic Area Considering Time-Dependent Properties of Concrete

The Arabic area is known for its significant changes in climate temperatures within different seasons. Riyadh, Cairo, Abu Dhabi, Ras Al-Khaimah, Kuwait, and Baghdad are subjected to the maximum variance in daily temperatures and presents the mean values of daily temperatures considering the data collected by the Hong Kong observatory in China for the last 30 years. The maximum mean value of daily temperature, which is 44.6 ℃ in Kuwait, and the minimum mean value of the daily temperature in Baghdad is 3.8 ℃. The maximum difference values of daily temperatures are observed in the Arabic Gulf area countries, such as Abu Dhabi, Kuwait, and Riyadh. Hence, these values will be considered in this analysis. This study results fit the thermal requirements of Arabic area and regions with similar temperature variation, accounting for various design aspects considering both methodologies of time-dependent properties of concrete as per CEB FIP 90 code and non-time dependent properties as per ACI 224.3R. For those targets a finite element method is utilized by generating 272 single- storey concrete ETABS models. The models are categorized according to column support conditions and development of concrete properties over time. The study findings are utilized to develop a clear understanding of mentioned variable's effects at thermal deformations and column reactions to aid structural engineers in the thermal design of super-long buildings with similar conditions of this study within time. The thermal displacement grows in proportion to the height of the column and the length of the slab. The findings of the analysis also show that employing thick slabs slightly decreases thermal displacements for models with hinged column supports and a 6 m column height. The thermal reactions increase in proportion to the length of the slab and the fixity conditions. Meanwhile, these reactions are inversely proportional to the height of the column. The ratios of time-dependent deformation and reaction to those of non-time-dependent properties are within the range [159%-163%] and [168%-171%] respectively. Ignoring this difference imposes defects, additional cracks, and damages at the structures and related serviceability conditions for 70 years period.

Experimental investigation of thermal performance of large-sized battery module using hybrid PCM and bottom liquid cooling configuration

A hybrid thermal management system (TMS) using phase change material (PCM) and bottom liquid cooling techniques for a large-sized power battery module was experimentally investigated. The system consisted of 106 test batteries in 18650 format, connected with a heat spreading plate, adjacent thermal columns and a cold plate populated with mini-channels installed beneath the module for liquid cooling to form the interconnected thermal structure. The experiment was conducted by heating the test batteries and monitoring representative battery temperatures. Three different heat dissipation options were studied with the same test bench, including the PCM cooling, liquid cooling and the hybrid cooling. Comparing with the liquid cooling, the hybrid cooling reduced the maximum battery temperature and temperature difference at steady-state. A temperature nonuniformity factor is introduced to evaluate the temperature difference across the module of different sizes. In addition, the test with the hybrid cooling for battery module under the cyclic working conditions exhibited sustaining temperature control, which is favorable for the battery module in continuous operation.

Optimization and designing collimator for boron neutron capture therapy at the thermal column of RTP

Boron Neutron Capture Therapy (BNCT) is a promising method to cure cancer by using interaction between boron compound and the slow neutron beam obtained from nuclear power reactor, nuclear research reactor and neutron generator. Based on the previous feasibility study shows that the thermal column can generate higher thermal neutrons for BNCT application at the TRIGA MARK II reactor. Currently, the facility for BNCT are planned to be developed at thermal column. Thus, the main objective was focused on the optimization of thermal neutron and epithermal neutron flux at the thermal column by designing collimator. This paper briefly goes through the characterization of collimator for the ideal neutron collimator design. Several collimators with variable geometries have been designed using Monte Carlo Simulation Codes of MCNPX. The results are then compared in term of thermal neutron, epithermal neutron and gamma fluxes yielded and the ideal collimator then optimize based on aperture size, shielding thickness and collimator condition This research is useful in the selection of neutron collimator design BNCT facility at the TRIGA MARK II reactor.

Release of C-14 and H-3 from Irradiated Graphite of the Thermal Column of VVR-S Reactor to Gas Phase

Release of C-14 and H-3 from Irradiated Graphite of the Thermal Column of VVR-S Reactor to Gas Phase

The research reactor TRIGA Mainz – a strong and versatile neutron source for science and education

Abstract The TRIGA Mark II-reactor at the Johannes Gutenberg University Mainz (JGU) is one of three research reactors in Germany. The TRIGA Mainz became first critical on August 3rd, 1965. It can be operated in the steady state mode with a maximum power of 100 kWth and in the pulse mode with a peak power of 250 MWth and a pulse length of 30 ms. The TRIGA Mainz is equipped with a central thimble, a rotary specimen rack, three pneumatic transfer systems, four beam tubes, and a graphite thermal column. The TRIGA Mainz is intensively used both for basic and applied research in nuclear chemistry and nuclear physics. Two sources for ultra-cold neutrons (UCN) are operational at two beam ports. At a third beam port a Penning-Trap for highly precise mass measurements of exotic nuclides is installed. Education and training is another main field of activity. Here, various courses in nuclear and radiochemistry, reactor operation and reactor physics are held for scientists, advanced students, engineers, and technicians utilizing the TRIGA Mainz reactor.

An Improved Parameterization for Retrieving Clear-Sky Downward Longwave Radiation from Satellite Thermal Infrared Data

Surface downward longwave radiation (DLR) is a crucial component in Earth’s surface energy balance. Yu et al. (2013) developed a parameterization for retrieving clear-sky DLR at high spatial resolution by combined use of satellite thermal infrared (TIR) data and column integrated water vapor (IWV). We extended the Yu2013 parameterization to Moderate Resolution Imaging Spectroradiometer (MODIS) data based on atmospheric radiative simulation, and we modified the parameterization to decrease the systematic negative biases at large IWVs. The new parameterization improved DLR accuracy by 1.9 to 3.1 W/m2 for IWV ≥3 cm compared to the Yu2013 algorithm. We also compared the new parameterization with four algorithms, including two based on Top-of-Atmosphere (TOA) radiance and two using near-surface meteorological parameters and water vapor. The algorithms were first evaluated using simulated data and then applied to MODIS data and validated using surface measurements at 14 stations around the globe. The results suggest that the new parameterization outperforms the TOA-radiance based algorithms in the regions where ground temperature is substantially different (enough that the difference between them is as large as 20 K) from skin air temperature. The parameterization also works well at high elevations where atmospheric parameter-based algorithms often have large biases. Furthermore, comparing different sources of atmospheric input data, we found that using the parameters interpolated from atmospheric reanalysis data improved the DLR estimation by 7.8 W/m2 for the new parameterization and 19.1 W/m2 for other algorithms at high-altitude sites, as compared to MODIS atmospheric products.

Thermal analysis of conjugated cooling configurations using phase change material and liquid cooling techniques for a battery module

A novel conjugated cooling configuration using phase change material (PCM) and liquid cooling techniques is proposed, and its thermal performance is investigated for a battery module. 106 cylindrical batteries are connected to the cold plate at the bottom through a heat spreading plate and the adjacent thermal columns, with PCM filled in between the gaps, which forms the cooling configuration. Three-dimensional numerical models are established for the cooling of the representative battery and battery module, which includes the battery connected to a liquid cooled mini-channel cold plate through the heat spreading plate and thermal column structures. The thermal characteristics of the battery incorporating the PCM melting and liquid cooling are examined at large flow rate. The geometrical parameters such as the size of the thermal column, the thickness of the heat spreading plate and the spacing of the batteries are investigated for the present conjugated cooling configuration. Both the battery temperature ramp-up rate and the steady-state battery temperature are significantly reduced by the conjugated cooling, in comparison with single PCM or liquid cooling conditions. The effects of various structure parameters on the thermal performance can be visualized by plotting the working time t50 vs the heat density based on the PCM volume. A comparison of the numerical simulation with the preliminary experiment work shows good agreement. This work can be useful in the design of conjugated configurations for the battery thermal management.

14C High Concentration Measurements with Relevance for Decommissioning of Nuclear Reactors

ABSTRACTDecommissioning of nuclear reactors requires determination of all remnant long-lived isotopes that were produced during their long functioning time of the respective facilities. Radiocarbon (14C) is such an isotope (T1/2 = 5730 yr), widely produced by neutron reactions in a thermal column of a nuclear reactor. Accelerator mass spectrometry (AMS) uses 14C for precise dating of up to 50,000 years old archaeological artifacts. This study presents a premier AMS measurement of high concentrated 14C samples that are strictly forbidden in laboratories dedicated to perform 14C dating. The determined 14C activities range from the natural level (isotopic ratio 14C/12C = 1.2 × 10–12) up to values of 10,000 times higher. 14C bulk and depth profile concentrations were measured in the thermal column disks of a decommissioned nuclear reactor. Results have shown that the 14C concentration in the thermal column, close the reactor core is about 75 kBq/g and decreases to 0.7 Bq/g and the end of the column. Such AMS measurements are applicable for decommissioning and waste management of nuclear reactors.

THE DOSE ANALYSIS OF BORON NEUTRON CAPTURE THERAPY (BNCT) TO THE BRAIN CANCER (GLIOBLASTOMA MULTIFORM) USING MCNPX-CODE WITH NEUTRON SOURCE FROM COLLIMATED THERMAL COLUMN KARTINI RESEARCH NUCLEAR

This research was aimed at discovering the optimum concentration of Boron-10 in concentrations range 20 µgram/gram until 35 µgram/gram with Boron Neutron Capture Therapy (BNCT) methods and the shortest time irradiation for cancer therapy. The research about dose analysis of Boron Neutron Capture Therapy (BNCT) to the brain cancer (Glioblastoma Multiform) using MCNPX-Code with a neutron source from Collimated Thermal Column Kartini Research Nuclear has been conducted. This research was a simulation-based experiment using MCNPX, and the data was arranged on a graph using OriginPro 8. The modelling was performed with the brain that contains cancer tissue as a target and the reactor as a radiation source. The variations of Boron concentrations in this research was on 20, 25, 30 and 35 μg/gram tumours. The outputs of MCNP were neutron scattering dose, gamma ray dose and neutron flux from the reactor. Neutron flux was used to calculate the doses of alpha, proton and gamma rays produced by the interaction of tissue material and thermal neutrons. Based on the calculations, the optimum concentration of Boron-10 in tumour tissue was for a 30 µg/gram tumour with the radiation dose in skin at less than 3 Gy. The irradiation times required were 2.79 hours for concentration 20 μg/gram ; 2.78 hours for concentration 25 μg/gram ; 2.77 hours for concentration 30 μg/gram ; 2.8 hours for concentration 35 μg/gram.

Release of 14C and 3H from Irradiated Graphite of the Thermal Column of VVR-S Reactor to Solution Phase

ABSTRACTGenerally, 14C is produced in all types of reactors, mainly through neutron-induced reactions with isotopes of carbon, nitrogen, and oxygen. These isotopes are present in the fuel, fuel cladding, coolant, moderator, and structural materials of the reactor. Irradiated graphite contains a range of activation products but, from the point of view of geological disposal, another radionuclide which has to be taken into account is tritium (3H or T), produced through the neutron induced reaction Li(n,α)T. In this study we have investigated the release of 14C and 3H into the solution phase from two intact samples of irradiated graphite which have been cut from the thermal column disc located near the VVR-S reactor core. To evaluate 14C and 3H long-term release in solution the graphite samples were submerged in a solution of 0.1 M of sodium hydroxide. The experimental results regarding the release of 14C and 3H from VVR-S irradiated graphite to liquid phase show that a major fraction of the total release occurs in the first months and a slower release on a long time scale. However, these results should be applied cautiously for long time prediction.

Thermal conductivity of sedimentary rocks in the Sichuan basin, Southwest China

The optical scanning method was adopted to measure the thermal conductivities of 418 drill-core samples from 30 boreholes in Sichuan basin. All the measured thermal conductivities mainly range from 2.00 to 4.00 W/m K with a mean of 2.85 W/m K. For clastic rocks, the mean thermal conductivities of sandstone, mudstone, and shale are 3.06 ± 0.73, 2.57 ± 0.42, and 2.48 ± 0.33 W/m K, respectively; for carbonate rocks, the mean thermal conductivities of limestone and dolomite are 2.53 ± 0.44 and 3.55 ± 0.71 W/m K, respectively; for gypsum rocks, the mean thermal conductivity is 3.60 ± 0.64 W/m K. The thermal conductivities of sandstone and mudstone increase with burial depth and stratigraphic age, but this trend is not obvious for limestone and dolomite. Compared with other basins, the thermal conductivities of sandstone and mudstone in Sichuan basin are distinctly higher, while the thermal conductivities of limestone are close to Tarim basin. The content of mineral composition such as quartz is the principal factor that results in thermal conductivity of rocks differing from normal value. In situ thermal conductivity of sandstones was corrected with the consideration of water saturation. Finally, a thermal conductivity column of sedimentary formation of the Sichuan basin was given out, which can provide thermal conductivity references for the research of deep geothermal field and lithospheric thermal structure in the basin.

Alternate Strategies for Optimal Unmanned Aerial Vehicle Thermaling

This paper investigates optimal glider trajectories for gaining altitude from thermal updraft columns (“thermaling”). Thermal updraft columns provide a natural energy resource that can be beneficial for enabling long-term autonomous soaring objectives. In this paper, computational optimal control is used to investigate possible alternatives to the common strategy of circularly orbiting the thermal to harvest potential energy. The Legendre–Gauss–Lobatto pseudospectral method is applied to a simulated glider in multiple scenarios over a range of thermal sizes, thermal intensities, and glider start conditions. Results for the Gedeon thermal model, which simulates dropoff in wind intensity with distance from the thermal core and additionally incorporates external downdrafts, are considered. These are then compared in performance to centered circular orbiting as well as two other alternate heuristic strategies suggested by the optimal control results: off-centered circular orbiting and “figure eights”. Results suggest benefits to using alternatives to centered circular orbiting when encountering small-diameter thermal updrafts. Results also support the utility of centered circular orbiting for medium- to large-diameter thermals while providing new insights into the optimal parameters of the circular orbit.

The characteristic time‐scale of perceived information for decision‐making: Departure from thermal columns in soaring birds

Abstract Animals are often required to make decisions about their use of current resources while minimising travel costs and risks due to uncertainty about the forthcoming resources. Passive soaring birds utilise warm rising‐air columns (thermals) to climb up and obtain potential energy for flying across large areas. However, the utilisation of such inconsistent natural resources may be challenging for soaring‐gliding birds and involve a set of decisions to maintain efficient flight. To assess which temporal scales of previous experience with environmental inputs best predicted thermal‐climbing departure decisions of soaring birds, we used movement data from Eurasian griffon vultures (Gyps fulvus) tracked by GPS transmitters. We applied Cox proportional hazard regression and a model selection approach to identify thermal‐climbing departure decisions and to compare a range of temporal scales. Our findings support the use of current and recent (short‐term; last 20 min) experiences, compared to longer term, past experiences, in predicting the time until departure from thermals. The models supported decision rules that integrated information originating from different temporal scales, implying a tendency to depart from a thermal later when the current climb rate was higher than experienced recently and vice versa. In addition, climb rates in thermals revealed significant autocorrelation over short time‐scales (shorter than 30 min). The correspondence between thermals' characteristics and the factors that best predicted thermal‐climbing departure decisions presumably reflects optimal decisions individuals make to handle their dynamic environment and to reduce movement‐related costs of such a basic activity for soaring‐gliding birds. A plain language summary is available for this article.

Effects of intensification on process features and control properties of lignocellulosic bioethanol separation and dehydration systems

Separation and dehydration process is a key step to reduce the total production cost of lignocellulosic bioethanol. In the earlier work (Torres-Ortega and Rong, 2016), we have obtained new intensified systems for lignocellulosic bioethanol separation and dehydration through dividing wall columns, which have considerable reduction to both capital and energy costs. This work presents the analysis of process features and control properties of the intensified systems with similar capital reduction and energy savings. The control properties were based on singular value decomposition (SVD) and dynamic performances under mild disturbances and changes of set point in Aspen Dynamics V8.8. The control properties and dynamic responses of the intensified separation systems were examined against the reference system for their structural changes during intensification by thermal couplings and column section recombination. The simultaneous analysis of process feature changes by intensification and their control properties achieved the intensified systems with both cost savings and competitive control properties.

Net Emission Coefficient and Radiation Transfer Characteristics of Thermal Plasma Generated in Nitrogen-PTFE Vapor Mixture

The radiation characteristics of thermal plasma columns filled with N2-polytetrafluoroethylene vapor mixture has been studied for the first time. The net emission coefficient is first calculated for typical mixture concentrations. The discrete ordinate method (DOM), which has proven to be an approximate method of reasonable accuracy for radiation transfer in thermal plasmas, is then used to characterize the emission and absorption behavior of cylindrical plasma columns with typical temperature distributions. Results show that the radiative power loss per unit volume at the column center is not always proportional to the local gas pressure. The DOM12-9 configuration, i.e., considering 24 directions in the $r$ -plane of the calculation point and 18 directions crossing the $r$ -plane, produces remarkably accurate results. It is likely to recover the accurate emission and absorption profile by scaling the output from the DOM5-3 configuration with a scaling factor between 0.7 and 0.8. Furthermore, the DOM5-3 configuration accurately locates the absorption layer at the edge of the plasma column. Maximum absorption takes place at a radial location whose distance to the inner radius of the absorption layer is 30% of the layer thickness despite of the very different radial temperature profiles. Under the conditions studied 35%–60% of the radiation from the central part of the column is absorbed in the surrounding cooler gas.