Localization of Plastic Deformation in the Copper and Stainless Steels Samples, Irradiated with Neutrons

The reduction of ductility of austenitic stainless steels as a result of long-term operation in the nuclear reactor core is an important problem of modern radiation materials science. Understanding the mechanisms of the effect of neutron irradiation on the mechanical properties of austenitic steels is impossible without research of localization processes occurring during the deformation. In this paper, it was found that the value of the true local deformation corresponding to the onset of neck formation in face-centered cubic structured metals decreases with an increase in the radiation dose, while the true stress remains almost constant. Additional hardening of AISI 304 steel due to the intensive formation of the martensitic α’-phase increases not only the stress at which a neck is formed in this alloy, but also the true local deformation. As a result, the uniform elongation increases and remains high after neutron irradiation to 0.05 dpa. The forehanded formation of the martensitic α’-phase in sufficient quantity before the necking onset can be considered as an additional deformation mechanism that will increase the ability of the material to deform uniformly.

Investigation of Al-B4C Metal Matrix Composites Produced by Friction Stir Additive Processing

Aluminium—boron carbide metal matrix composites (Al-B4C MMCs) belong to the class of materials extensively used in the nuclear industry as a thermal neutron absorber in spent fuel casks. This article investigates a novel production method of Al-B4C MMCs—Friction Stir Additive Processing (FSAP)—as an alternative production method to casting or sintering. FSAP is derived from friction stir welding, which can be used to local modifications of microstructure, or it can be used to incorporate the second phase into the processed material. During this study, a variant of FSAP for MMC production was proposed, and its mechanical and thermal neutron absorbing properties have been investigated. Further, the influence of neutron irradiation on mechanical properties has been studied. Results show that FSAP can successfully produce Al-B4C MMCs with 7 mm thickness. Neutron irradiation causes only a slight increase in hardness, while its effect on tensile properties remains inconclusive.

Fast neutron irradiation long term effect on Ocimum basilicum germination and initial vegetative parameters

The goal of this study is to assess the long-term (3-year) effects of rapid neutron irradiation using an Americium-Beryllium source on two generations (M0 and M1) of Ocimum basilicum commercial trait. Seeds of each variety and generation were irradiated with 0, 7.5, 20, 40, and 50 Gray in 2018, and then seeded in 2021 – with their corresponding controls – to see how the different irradiation treatments affected germination and early vegetative metrics three years after irradiation. In the first generation, no significant changes between the treatments were seen. Increased irradiation dosage resulted in a significant decrease in germination % in the second generation (M1), but a significant increase in seedling height. The M0 generation seedlings, on the other hand, were substantially shorter than controls. In the M0 generation, the higher dosages (40 and 50 Gray) were deadly, and seedlings were terminated 7–10 days after germination. The irradiation dose of 20 Gray was shown to be the most successful in inducing viable and beneficial alterations for phenotypic characteristics in basil. When compared to control plants, the lower (7.5 and 20 Gray) bombardment generated leaf anomalies such as smaller leaves and internodes, a split apex, and a ribbon-like stem.

Efficacy of Boron Neutron Capture Therapy in Primary Central Nervous System Lymphoma: In Vitro and In Vivo Evaluation

Background: Boron neutron capture therapy (BNCT) is a nuclear reaction-based tumor cell-selective particle irradiation method. High-dose methotrexate and whole-brain radiation therapy (WBRT) are the recommended treatments for primary central nervous system lymphoma (PCNSL). This tumor responds well to initial treatment but relapses even after successful treatment, and the prognosis is poor as there is no safe and effective treatment for relapse. In this study, we aimed to conduct basic research to explore the possibility of using BNCT as a treatment for PCNSL. Methods: The boron concentration in human lymphoma cells was measured. Subsequently, neutron irradiation experiments on lymphoma cells were conducted. A mouse central nervous system (CNS) lymphoma model was created to evaluate the biodistribution of boron after the administration of borono-phenylalanine as a capture agent. In the neutron irradiation study of a mouse PCNSL model, the therapeutic effect of BNCT on PCNSL was evaluated in terms of survival. Results: The boron uptake capability of human lymphoma cells was sufficiently high both in vitro and in vivo. In the neutron irradiation study, the BNCT group showed a higher cell killing effect and prolonged survival compared with the control group. Conclusions: A new therapeutic approach for PCNSL is urgently required, and BNCT may be a promising treatment for PCNSL. The results of this study, including those of neutron irradiation, suggest success in the conduct of future clinical trials to explore the possibility of BNCT as a new treatment option for PCNSL.

TB-6 Experimental evaluation of the therapeutic potential of boron neutron capture therapy in primary central nervous system lymphoma

Background: High-dose methotrexate and whole brain radiation therapy (WBRT) is the recommended treatment for primary central nervous system lymphoma (PCNSL). Although the initial treatment is successful, the recurrence rate is high and the prognosis is poor. Boron neutron capture therapy (BNCT) is a nuclear reaction-based tumor cell-selective particle irradiation that occurs when non-radioactive boron-10 is irradiated with neutrons to produce α particles (10B [n, α] 7Li). In this study, we conducted a basic research to explore the possibility of BNCT as a treatment option for PCNSL. Methods: Cellular uptake of boron using human lymphoma cell-lines after exposure to boronophenylalanine (BPA) were evaluated. The cytotoxicity of lymphoma cells by photon irradiation or neutron irradiation with BPA were also evaluated. The lymphoma cells were implanted into the mouse brain and the bio-distribution of boron after administration of BPA were measured. In neutron irradiation studies, the therapeutic effect of BNCT on mouse CNSL models were evaluated in terms of survival time. Results: The boron concentration in lymphoma cells after BPA exposure was sufficiently high, and lymphoma cells showed cytotoxicity by photon irradiation, and also by BNCT. In in vivo bio-distribution study, lymphoma cells showed enough uptake of BPA with well contrasted to the brain. In the neutron irradiation experiment, the BNCT group showed a significant prolongation in their survival time compared to the control group. Conclusions: In our study, BNCT showed its effectiveness for PCNSL in a mouse brain tumor model. PCNSL is a radio-sensitive tumor with a extremely good response rate, but it also has a high recurrence rate / a high rate of adverse events, so there is no effective treatment for recurrence after treatment. Our translational study showed that BNCT is possibly have an important role against PCNSL during the therapy lines as a new treatment option for PCNSL patients.