FeCrNi medium entropy alloys as potential shielding materials for nuclear applications.

Metallic alloys of different compositions are basic structures for building different types of nuclear reactors. This study evaluates the nuclear properties for three medium entropy alloys against incident neutrons and gamma radiation. The alloys had different chemical compositions prepared by powder technology and were compared with two stainless steel alloys for use in constructing different parts of nuclear power plant units.

Nuclear-excited source of coherent and incoherent radiation with direct nuclear pumping.

Uranium fission fragments, as well as the products of He(n,p)H and B(n,α)Li nuclear reactions were utilized in the nuclear reactor for gas ionization and excitation. However, the Li(n,α)H nuclear reaction was less examined. The use of lithium-6 as a surface source of excitation of the gas medium, due to the long path length of tritium nuclei in the gas, allows to excite large volumes of gas as opposed to using U or B.

Stopping criteria for neutron spectrum unfolding algorithms.

Neutron spectrum unfolding is a crucial process in radiation protection and dosimetry. Unfolding codes using iterative algorithms require a criterion to stop the iterations. One approach often relies on the Root Mean Square Error (RMSE) criterion to assess the convergence of iterative algorithms.

Neutron pumping of active medium formed by gadolinium isotopes Gd and Gd pair: A feasibility study.

The possibility of creating technical means for controlling the processes of accumulation and conversion of the energies of thermal and epithermal neutrons into the energy of monoenergetic photons due to neutron pumping of an active medium consisting of nuclei with long-lived isomeric states was studied in this work. The system under study consisted of an external pulse-periodic source of deuterium-tritium neutrons (PSN) and a subcritical blanket, which included a variable neutron-collimation beam-shaping assembly (vBSA) and an active medium. The vBSA was composed of moderating blocks and selective plates designed to trap and shape a pulsed neutron flux with subsequent conversion of a millisecond signature into monoenergetic photon emission.

Comparison of H*(10) estimations, due to neutrons and γ-rays, around FANT with two Am/Be sources.

FANT (Fuente Ampliada de Neutrones Térmicos; in Spanish) is a thermal neutron irradiation facility with an extended and very uniform irradiation area, which has been developed by the Neutron Measurement Laboratory of the Energy Engineering Department at Universidad Politécnica de Madrid (LMN-UPM). In FANT, an isotopic neutron source (Am/Be) produces the primary neutrons. The design and facility optimization were carried out by extensive Monte Carlo calculations.

Mechanical and radiation shielding characterization of W-based alloys for advanced nuclear unit.

The paper aims to investigate the mechanical and radiation shielding properties of two tungsten-based alloys manufactured by powder technology; their features when compared with two standard stainless steel grades for advanced nuclear applications. Multiple measurements were performed to characterize the alloys' structural and mechanical properties. XRD analysis and average surface roughness measurements showed the crystalline and morphological structure of the alloys.

Dosimetric evaluation of I (Iodide) and Tc (Pertechnetate) in the thyroid of neonates using Cristy-Eckerman and Segars anatomical representations.

Using the MIRD formalism, and the Cristy-Eckeman and Segars anthropomorphic representations, the absorbed dose in the thyroid of newborns, was calculated when I (iodide) and Tc (pertechnetate) are used during the diagnostic procedures. The dose results will allow exploring the dosimetric impact generated by the use of these radiopharmaceutical compounds and the use of two representations. Regardless the radiopharmaceutical compound and the anthropomorphic representation is the thyroid self-dose is the greatest, due to electrons emitted during the I and Tc radioisotopes.

Spectra, fluence and absorbed doses in sensitive organs due to scattered X-rays during a chest CT.

The use of ionizing radiation for the treatment and diagnosis of diseases is becoming more frequent. The technologies associated with diagnostic imaging are constantly evolving, allowing faster and cheaper diagnoses to benefit the patient. However, this has caused an increase in the exposure to ionizing radiation of patients and health professionals.

Estimation with Monte Carlo of thermal neutrons in the FANT, using Cf and Am/Be neutron source.

The thermal neutron irradiation device (FANT), developed at the Neutron Measurements Laboratory of the Energy Engineering Department at Universidad Politécnica de Madrid, is a high-density polyethylene regular parallelepiped, with a rather uniform neutron fluence inside its irradiation chamber. It uses a Am95241/Be49 neutron source aiming to provide thermal neutron fluence rates. Neutron spectra and neutron fluences were estimated with Monte Carlo methods in the FANT irradiation chamber when a Cf98252 neutron source is used and were compared with the results obtained with the Am95241/Be49 source.

How much should you worry about contaminant neutrons in spatially fractionated grid radiation therapy?

Neutron contamination in radiation therapy is of concern in treatment with high-energy photons (> 10 MV). With the development of new radiotherapy modalities such as spatially fractionated grid radiation therapy (SFGRT) or briefly grid radiotherapy, more studies are required to evaluate the risks associated with neutron contamination. In 15 MV SFGRT, high-Z materials such as lead and cerrobend are used as the block on the tray of linear accelerator (linac) which can probably increase the photoneutron production.

Improving the properties of commercial steel alloys in the industrial/nuclear field by RF plasma carbonitriding.

The study investigates the effect of RF plasma on the commercial SS201 and Steel alloys physical, structural and nuclear properties, using an atmosphere of nitrogen (85%) plus acetylene (15%) at 500 W working for 0.5 h. The results were compared with untreated alloys and AISI304L.

Doses and spectra, of leaking-out and scattered photons from X-ray tubes used in dentistry.

Diagnosis by X-ray image are procedures widely used to improve the diagnosis or to follow the evolution of a medical procedure, also are used to support the cancer treatment with linear accelerators. The procedure involves the X-ray unit and the detection system, while the X-ray beam is projected onto the patient; along this procedure X-rays are scattered out from the patient body and X-rays leak-out from the X-ray unit. Both, the scattered and the leaking out radiation, are important during the evaluation or the design of the shielding barriers.

Effect of changing the neutron moderator in a thermal subcritical nuclear reactor.

Subcritical thermal nuclear reactor is the combination of nuclear fuel, moderator and external neutron source. Nevertheless, the amount of neutrons increases through nuclear fissions in the U in the fuel, the absorption and leakage of neutrons maintain the subcriticality condition. There are several subcritical reactors with different features and purposes.

Age-specific calibration for in vivo monitoring of thyroid: is it necessary?

Usually, an age-specific calibration of detectors used for in vivo monitoring of I thyroid radioactivity is not performed in practice. This study aimed to investigate the reduction in uncertainty that one can expect if an age-specific calibration is performed. For this, voxel and stylized computational phantoms of the thyroid, corresponding to children at different age groups, were used to simulate the calibration process of I detectors used for thyroid monitoring.

Characteristics, as a shield against ionizing photons, of concrete blocks used in the construction industry.

INEGI reports that 81% of new constructions are built with durable materials, such as concrete blocks, including rooms where ionizing radiation is used, such as clinics and hospitals. The volume ratios used in the manufacture of concrete blocks have a 1: 5: 2 ratio of: portland cement, sand and crushed gravel. The percentage mass content of each atom in the sample is obtained with the energy-dispersed X-ray fluorescence, these results are used to calculate the characteristics such as shielding of the concrete blocks, which have been partially reported, in this work several characteristics are presented for photons from 1 keV to 100 GeV, such as linear attenuation coefficients, the hemireductive layer, the effective, atomic and electronic sections, the effective atomic number (Zef).

Gamma-ray energy spectrum unfolding of plastic scintillators using artificial neural network.

In this study, the unfolding of the plastic scintillator spectrum was undertaken using the artificial neural networks tools of MATLAB. To this purpose, the response matrix of the plastic scintillator was generated for 145 energy groups and in 512 pulse-height channels using the MCNPX2.6 code.

Mathematical description of the effect of HIF inhibition on the radiobiological response of LNCaP cells.

According to the National Institute of Public Health, prostate cancer (PCa) is the leading cause of cancer death in Mexican men, highly associated with aggressiveness, resistance to treatment, and metastatic spread (Bharti et al., 2019) mediated by activation of the hypoxia-inducible factor 1 (HIF-1α). The objective of the present study was to evaluate the participation of HIF-1α activation in the radiobiological response of the human prostate adenocarcinoma cell line LNCaP, describing the phenomena with a mathematical model.

Feasibility of 18-MV grid therapy from radiation protection aspects: unwanted dose and fatal cancer risk caused by photoneutrons and scattered photons.

Purpose: Photoneutron production is a common concern when using 18-MV photon beams in radiation therapy. In Spatially Fractionated Grid Radiation Therapy (SFGRT), the grid block in the collimation system modifies the neutron production, photon scattering, and electron contamination in and out of the radiation field. Such an effect was studied with grids made of different high-Z materials by Monte Carlo simulations.

Beam port filters in a TRIGA MARK III nuclear reactor to produce epithermal neutrons for BNCT.

Glioblastoma multiforme is the most common and aggressive brain tumor and it is difficult to treat with conventional surgery, chemotherapy, or radiation therapy. An alternative treatment is boron neutron capture therapy which requires an energy modulated beam of neutrons and aB drug capable of adhering to the tumor. In this work, MCNP6 Monte Carlo code was used to evaluate the effect on the neutron spectrum by placing two filters along the radial beam tube of the TRIGA Mark III nuclear reactor of ININ in Mexico.

Monte Carlo evaluation of out-of-field dose in 18 MV pelvic radiotherapy using a simplified female MIRD phantom.

This study was devoted to determining the unwanted dose due to scattered photons to the out-of-field organs and subsequently estimate the risk of secondary cancers in the patients undergoing pelvic radiotherapy. A typical 18 MV Medical Linear Accelerator (Varian Clinac 2100 C/D) was modeled using MCNPXcode to simulate pelvic radiotherapy with four treatment fields: anterior-posterior, posterior-anterior, right lateral, left lateral. Dose evaluation was performed inside Medical Internal Radiation Dose (MIRD) revised female phantom.

Comparison of FANT results using the ENDF/B-VII.1, JEFF-3.3 and TENDL2017 nuclear data libraries.

FANT (Fuente Ampliada de Neutrones Térmicos; in Spanish) is a thermal neutron irradiation facility with an extended and very uniform irradiation area, that has been developed by the Neutron Measurements Laboratory of the Energy Engineering Department at Universidad Politecnica de Madrid (LMN-UPM). This device is a parallelepiped box made of high-density polyethylene (HDPE), moderator material, that uses an A95241m/B49e neutron source of 111 GBq nominal activity for irradiating materials. The facility design was previously optimized, and the neutron spectra were estimated by extensive calculations with the MCNP6.

Dosimetric evaluation of radiopharmaceuticals in kidneys and uterine wall of a woman with early pregnancy using Stabin/Segars representations.

MIRD method with the Stabin/Segars anthropomorphic representations were used to calculate the absorbed doses in kidneys and uterine wall of an early-stage pregnant woman when Tc (DTPA), Tc (DMSA) and Tc (MAG3) are used for renal studies. Stabin and Segars anatomical representations are phantoms that are used in Monte Carlo calculations to determine the SAF, that with the pharmaceutical residence time are used to calculate the absorbed dose, from source organs, on target organs. Concerns about the impact on the absorbed dose due to the use of the three Tc-based compounds as well as the use of different phantoms were here treated for the case of a female at early pregnant state.

Gamma-ray spectroscopy with anode pulses of NaI(Tl) detector using a low-cost digitizer system.

Recently, digital gamma-ray spectroscopy employing low-cost and publicly available (Commercial off the shelf) digitizers has been frequently used in different studies worldwide. In this paper, we considered the digital methods for gamma-ray spectroscopy in which the anode pulses of the photomultiplier tube (PMT) output in a NaI(Tl) scintillation detector were immediately digitized by a PC sound card. We introduced and developed the methods for gamma-ray spectroscopy of microCurie gamma-ray sources by a sampling rate of 96 kHz.