Fast Neutron Irradiation Research Articles

Genomics of predictive radiation mutagenesis in oilseed rape: modifying seed oil composition.

Rapeseed is a crop of global importance but there is a need to broaden the genetic diversity available to address breeding objectives. Radiation mutagenesis, supported by genomics, has the potential to supersede genome editing for both gene knockout and copy number increase, but detailed knowledge of the molecular outcomes of radiation treatment is lacking. To address this, we produced a genome re-sequenced panel of 1133 M2 generation rapeseed plants and analysed large-scale deletions, single nucleotide variants and small insertion-deletion variants affecting gene open reading frames. We show that high radiation doses (2000 Gy) are tolerated, gamma radiation and fast neutron radiation have similar impacts and that segments deleted from the genomes of some plants are inherited as additional copies by their siblings, enabling gene dosage decrease. Of relevance for species with larger genomes, we showed that these large-scale impacts can also be detected using transcriptome re-sequencing. To test the utility of the approach for predictive alteration of oil fatty acid composition, we produced lines with both decreased and increased copy numbers of Bna.FAE1 and confirmed the anticipated impacts on erucic acid content. We detected and tested a 21-base deletion expected to abolish function of Bna.FAD2.A5, for which we confirmed the predicted reduction in seed oil polyunsaturated fatty acid content. Our improved understanding of the molecular effects of radiation mutagenesis will underpin genomics-led approaches to more efficient introduction of novel genetic variation into the breeding of this crop and provides an exemplar for the predictive improvement of other crops.

Gamma, neutron, and charged particle shielding performance of ABKT glass system

In this study, the gamma, charged, thermal neutron, and fast neutron radiation shielding parameters of (5+x)K2O-(25-x)TeO2-(10-x)As2O3-(60-x)B2O3 (where x ranged from 0 (ABKT1) to 20 (ABKT5) mol% in 5 mol% steps) were calculated and simulated. In addition, important optical parameters such as the reflection loss (Rloss), molar refractivity (Rm), molar polarizability (αm), optical transmission (TOpt), metallization criterion (M(n)), static dielectric constant (Ɛsta), optical dielectric constant (Ɛopt) of the glasses, were computed and juxtaposed with the chemical composition of the glasses. The values of Rm and αm decreased from 17.213 cm3/mol to 15.247 cm3/mol and 6.830 x10−24 cm3 to 6.05 x10−24 cm3, respectively, as K2O replaced TeO2 in the ABTK glass system. Similarly, Rloss reduced from 0.173 to 0.164, while TOpt increased from 0.705 to 0.719. The values of M(n), εsta, and εOpt were in the range 0.381–0.397, 5.565–5.87, and 4.565–4.871, respectively. The mass attenuation coefficients of ABKT1–ABKT5 were within the range of 0.0276–30.8789, 0.0269–29.6485, 0.0262–28.3373, 0.0255–29.9370, and 0.0249–25.4384 cm2/g, respectively. ABKT1 is the best gamma photon absorber among the ABKT glasses for narrow and broad beam transmission modes. For electrons, protons, alpha particles, and heavy carbon ions, the mass stopping powers of the glasses follow the order ABKT1>ABKT2>ABKT3>ABKT4>ABKT5. ABKT1 had the best photon and ion absorbing capabilities, while ABKT5 has the highest thermal and fast neutron interaction cross-sections. The ABKT1 glass demonstrated the potential to perform better than some commercial glass shields, standard shielding glasses, light and heavy concretes, and a host of other materials as a transparent gamma radiation shielding material.

Neutron irradiation impact on structural and electrical properties of polycrystalline Al2O3

High energy neutron irradiations impact on structural and electrical properties of alumina are studied with particular emphasis on real time in-situ radiation induced conductivity measurement in low flux region. Polycrystalline Al2O3 samples are subjected to high energy neutrons produced from D-T neutron generator and Am–Be neutron source. 14 MeV neutrons from D-T generator are chosen to study the role of fast neutron irradiation in the structural modification of samples. Real time in-situ electrical measurement is performed to investigate the change in insulation resistance of Al2O3 due to radiation induced conductivity at low flux regime. During neutron irradiation, a significant transient decrease in insulation resistance is observed which recovers relative higher value just after neutron exposure is switched off. XRD results of 14 MeV neutron irradiated samples suggest annealing effect. Impact of relatively low energy neutrons on the structural properties is also studied using Am–Be neutrons. In this case, clustering is observed on the sample surface after prolonged neutron exposure. The structural characterizations of pristine and irradiated Al2O3 samples are performed using XRD, SEM, and EDX. The results from these characterizations are analysed and interpreted in the manuscript.

Effects of Fast Neutron Irradiation on Switching of Silicon Bipolar Junction Transistor

Background: When bipolar junction transistors (BJTs) are used as switches, their switching characteristics can be deteriorated because the recombination time of the minority carriers is long during turn-off transient. When BJTs operate as low frequency switches, the power dissipation in the on-state is large. However, when BJTs operate as high frequency switches, the power dissipation during switching transients increases rapidly.Materials and Methods: When silicon (Si) BJTs are irradiated by fast neutrons, defects occur in the Si bulk, shortening the lifetime of the minority carriers. Fast neutron irradiation mainly creates displacement damage in the Si bulk rather than a total ionization dose effect. Defects caused by fast neutron irradiation shorten the lifetime of minority carriers of BJTs. Furthermore, these defects change the switching characteristics of BJTs.Results and Discussion: In this study, experimental results on the switching characteristics of a pnp Si BJT before and after fast neutron irradiation are presented. The results show that the switching characteristics are improved by fast neutron irradiation, but power dissipation in the on-state is large when the fast neutrons are irradiated excessively.Conclusion: The switching characteristics of a pnp Si BJT were improved by fast neutron irradiation.

Intensity-Modulated Neutron Therapy (IMNT) for Head and Neck Cancer: Early Toxicity Outcomes

Locally advanced head & neck cancers (HNC) are challenging to treat due to abutment of critical, dose-limiting structures. Fast neutron radiotherapy (NT) is a high linear energy transfer (LET) modality that provides better local control than photons for radioresistant cancers such as salivary gland tumors, but there have been concerns of toxicity with 3D conformal neutron therapy in the past. Recent technological advances have enabled the planning and delivery of IMNT, which improves target conformality and may reduce toxicity compared to 3D conformal NT. We report the first clinical evaluation of early toxicity outcomes of IMNT for HNC. Study is a single-institution retrospective review of all HNC patients treated with curative-intent IMNT from 10/2022 to 2/2023, using a hospital-based cyclotron (50.5 MeV 1H+ beam incident on a Be target) equipped with an isocentric gantry and multileaf collimator (MLC). A commercial treatment planning system with custom neutron-specific scattering kernels was used for IMNT planning using 4-6 fields. Patient-specific quality assurance included ionization chamber measurements and a novel 12C(n,2n)11C positron emission portal imaging system. kV portal imaging was used to confirm patient setup prior to each treatment session. All patients were prescribed 18.4 Gy at 1.15 Gy/fraction, delivered 4 days/week, which is equivalent to an x-ray EQD2 of approximately 70 Gy (RBE ∼ 3.8). Clinical observations suggest the RBE for radioresistant HNC may be as large as 8. Patients underwent weekly toxicity assessment, and acute toxicities were graded (G) by CTCAE v5.0. Ten patients received IMNT, median age 61 (range 34-78). Primary tumor sites were base of tongue (n = 3), sinonasal (n = 3), parotid (n = 2), submandibular (n = 1), larynx (n = 1). Tumor histologies included adenoid cystic carcinoma (n = 7), other salivary gland carcinomas (n = 2) and mucosal melanoma (n = 1). Most had T4 disease (n = 8) and one had N3b disease. Six had surgical resection with high-risk features, and 6 had gross measurable disease prior to IMNT. None had concurrent systemic therapy. Uninvolved salivary glands were spared in most patients. All patients completed treatment. Median follow up was 22 days (0-48). Acute toxicities (n, G 1, 2, 3) included skin (8, 3, 0), dysgeusia (1, 6, 0), xerostomia (3, 5, 0), mucositis (2, 0, 5), nausea (3, 0, 1). One patient had >10% weight loss and brief admission for supportive care and PEG placement; one patient had prophylactic PEG; both regained oral independence during follow-up. There was no Grade 4+ toxicity. IMNT improves the therapeutic ratio compared to 3D conformal NT and expands indications for NT in patients with radiorefractory tumors. Acute toxicity compares favorably with photons. Longer clinical and toxicity follow-up is anticipated. A prospective trial is planned to evaluate quality of life measures.

In situ observation of crystal reorientation in polygranular graphite by synchrotron X-ray diffraction and neutron imaging

The capacity of polygranular graphite to accommodate strain is important to its use within structural components. This study has used in situ neutron and synchrotron X-ray experiments to demonstrate that reorientation of crystal domains accompanies the accommodation of applied mechanical strain in unirradiated Gilsocarbon (GCMB/IM24) graphite. Orientation changes were observed using 3D X-ray Diffraction, and local changes in neutron scattering were also observed with energy-resolved Bragg-edge neutron imaging. In both cases, this behaviour at the crystal level was partially recovered when the load was removed. This study provides new evidence for crystal deformation mechanisms that contribute to polycrystalline graphite's elastic non-linearity and the development of permanent set, which may also explain the effects of fast neutron irradiation on graphite elastic behaviour.

Comparing neutron and helium ion irradiation damage of REBa2Cu3O coated conductor using x-ray absorption spectroscopy

Understanding the effects of high energy neutron damage on REBa2Cu3O (REBCO) coated conductor is of vital importance for the design of the magnetic confinement systems for compact nuclear fusion power plants. However, neutron irradiation campaigns can only be carried out in a few facilities, and the experiments are very slow and expensive partly because the samples become radioactive. Ion irradiation provides an easily accessible alternative route to studying the effects of radiation on high temperature superconductors, which not only increases the volume of technical data that can be obtained but also enables more complex experiments such as in situ cryogenic irradiation. The question is, does ion damage offer a good proxy for neutrons? Here we use high energy resolution fluorescence detected x-ray absorption spectroscopy to probe the effects of fast neutron irradiation on the local environment around the copper ions in the REBCO layer of coated conductor tapes. We find that the spectral changes are similar to those induced by helium ion irradiation, suggesting that both projectiles produce the same types of structural defect in the REBCO lattice, although there is some evidence of an additional type of defect present in the sample heavily damaged by He+ ion irradiation. It is also shown that the linear degradation of superconducting transition temperature (T c ) of coated conductors with the calculated number of displacements per atom occurs at the same rate for neutrons and helium ions. Together these results provide new evidence suggesting that helium ions can emulate neutron point defect damage in REBCO high temperature superconductor reasonably well, increasing confidence that helium ions could be used as a useful proxy for neutrons in future experiments.

Tensile properties of modified 316 stainless steel (PNC316) after neutron irradiation over 100 dpa

ABSTRACT The effects of fast neutron irradiation on tensile properties of 20% cold-worked modified 316 austenitic stainless steel (PNC316), which was improved swelling resistance and creep strength, claddings and wrappers for fast reactors were investigated. PNC316 claddings and wrappers were irradiated in the experimental fast reactor Joyo at irradiation temperatures between 400°C and 735°C to fast neutron doses ranging from 21 to 125 dpa. The post-irradiation tensile tests were carried out at room and irradiation temperatures. Elongations of PNC316 measured by the tensile tests were maintained at an engineering level, although the material incurred significant irradiation hardening and softening depending on irradiation temperature. The maximum swelling of PNC316 wrappers was about 2.5 vol.% at irradiation temperature between 400°C and 500°C up to 110 dpa. Japanese 20% cold-worked austenitic steels, PNC316 and 15Cr-20Ni, had sufficient ductility and work-hardenability even after above 10 vol.% swelling, while they had very weak plastic instabilities.

Radiation characterizations of two isotopic neutron sources merging in one irradiator for experimental applications in the laboratory

Neutron sources are utilized for different aims, such as studying the material’s internal structure, investigating the materials’ crystal structures, and neutron therapy. Using more than one isotopic neutron source in some aims could be beneficial. Herein, a neutron irradiator consisting of two 241Am-9Be neutron sources has been designed. Radiation characterizations, including the neutron fluence and dose rate, were investigated. The Monte Carlo simulation code Monte Carlo N-particle transport code version 5 (MCNP5) was used to conduct all the required investigations to achieve an optimal design. Two factors were considered; the first was the dose rate due to both neutron and gamma radiations to meet radiation protection requirements; MCNP5 was used to determine the adequate thickness of the shielding material. The second parameter is the neutron fluence. Two irradiation sites have been proposed, one for fast neutron irradiation and the other for thermal neutron irradiation. By utilizing MCNP5, we have determined the radiation characterization at the two sites to be used as the irradiation sites. After the optimal design had been produced, the thermal and the epithermal neutron fluences inside the two irradiation sites were determined experimentally. The experimental results showed a perfect agreement with the simulation ones. The neutron irradiator designed from merged two isotopic neutron sources could be a benefit in the neutron radiation applications in the labs.

The effect of phosphorus on precipitation in irradiated reactor pressure vessel (RPV) steels

Embrittlement of light water reactor pressure vessel (RPV) steels by fast neutron irradiation may limit extended nuclear plant life. Embrittlement, which is manifested as increases in various indexes of a ductile to brittle transition temperatures (ΔT), is primarily due to hardening by nanoscale precipitates containing Cu, Ni, Mn, and Si, which form under irradiation. In addition to these elements, P has also been found to play a role in embrittlement. While only slightly enriched in the precipitates, hardening and embrittlement increase with trace P concentrations in low-Cu steels. Here, we characterize the individual and synergistic irradiation precipitation and hardening mechanisms in a series of RPV steels containing no to low-Cu and with systematic variations in Ni and P. The steels were irradiated to a fluence of ∼ 1.38×1020 n/cm2 at ∼ 292 °C in the UCSB ATR-2 experiment. In nominally Cu-free medium and high-Ni RPV steels, atom probe tomography shows that P and Ni promote precipitation of P-Mn-Si-Ni and Mn-Si-Ni precipitates, respectively. The precipitate microstructure correlates with the observed irradiation hardening.

Understanding the nanoscale chemistry of as-received and fast neutron irradiated Nb3Sn RRP® wires using atom probe tomography

Atom probe tomography (APT) has been used to study the effect of fast neutron irradiation on the local chemistry of Nb3Sn samples. Two RRP® wires doped with 2 at% Ti were analysed, one in the as-received condition and the other irradiated to a neutron fluence (E > 0.1 MeV) of 2.82 × 1022m−2 in the TRIGA-II reactor. The irradiated sample had a reduced T c, an increase in F p, a shift in the peak of the F p curve suggesting the introduction of secondary point pinning, and an increase in the estimated scaling field B*. APT analysis has shown that polycrystalline Nb3Sn has three distinct regions of composition, near stoichiometry Nb3Sn (low Nb), regions with a higher Nb content than expected in equilibrium Nb3Sn (high Nb) and grain boundaries. The summed composition of these three regions lies within the Nb3Sn phase for both the as-received and irradiated samples. The distinct regions of high Nb Nb3Sn demonstrate incomplete diffusion in the as-received sample, and the reduction in volume of these high Nb regions after irradiation implies significant radiation induced diffusion has occurred. The presence of other features in the atomic-scale chemistry, such as the extent of Cu segregation at grain boundaries, three types of dislocation array, and unreacted Nb nanoparticles, are compared between samples.

Microstructural evolution of TiC nano powders under fast neutron irradiation: A multi-technique analysis

In this work, titanium carbide nano powders were irradiated at normal conditions of 293.15 K and 1 atm with fluencies of 4.0 × 1012 n/cm2, 8.0 × 1012 n/cm2, 1.3 × 1013 n/cm2, 4.0 × 1014 n/cm2, and 1015 n/cm2 (neutron energy 1 MeV). The microstructure of the titanium carbide nano powders after irradiation was examined using X-ray diffraction, Raman spectroscopy, and FTIR spectroscopic analysis methods. The X-ray diffraction analysis revealed that no significant phase transition or amorphization occurred in the TiC nano powders exposed to fast neutrons. More sensitive results obtained from the FTIR analysis showed that the water molecules absorbed on the material surface were disintegrated under the influence of fast neutrons. Exceptional structural stability to neutron irradiation of titanium carbide without amorphization was also observed by morphological analysis via transmission electron microscopy (TEM) and selected area electron diffraction (SEAD).

Novel method for fast neutron irradiation of materials via positron emission tomography isotope producing cyclotron

A proof-of-principle experiment for the irradiation testing of candidate reactor materials utilizing fast neutrons from a cyclotron as it produces clinical Positron Emission Tomography (PET) isotopes is presented. The reaction 18O(p, n)18F results in 18F for use in the radio-pharmaceutical fluorodeoxyglucose, as well as a significant flux of by-product fast neutrons. In this work, wrought forms of alloy Inconel 625 and its additively manufactured counterpart were placed in near proximity to the 18F producing cyclotron targets. The microhardness values were tracked periodically for over 25 weeks as the samples acquired fast neutron dose; up to approximately 9 × 1015 1-MeV-equivalent n/cm2. Hardness values for the wrought sample evolved with dose, by as much as ∼15% throughout the experiment. However, the additively manufactured samples remained relatively unchanged under identical dose. These results demonstrate the promising feasibility of using this irradiation method to explore mechanical property changes in nuclear-relevant alloys under low-dose conditions.

Effect of Si and Nb additions on carbonitride coatings under proton irradiation: A comprehensive analysis of structural, mechanical, corrosion, and neutron activation properties

In the present study, understoichiometric TiZrCN, TiZrNbCN, and TiZrSiCN coatings were produced using the cathodic arc technique with a C/N ratio of approximately 0.5 to investigate their potential use in nuclear technology. The coatings were evaluated for their corrosion resistance in 3.5 % NaCl and neutron activation. The effect of adding Si and Nb to the quaternary TiZrCN system was also investigated. The results showed that the addition of Si (∼4.64 at.%) to the matrix of TiZrCN improved their electrochemical properties in NaCl solution, the protective efficiency was 92%, while the Nb addition (∼5.5 at%) lead to the decrease in corrosion resistance by 1.39 times comparing with TiZrCN. Furthermore, after fast neutron irradiation at a nominal power of 1450 kW, none of the coatings were activated, indicating good radiation resistance. It was determined from the structural analysis that the Ti6Al4V substrate before corrosion consists of hexagonal and cubic space groups with different lattice parameters. By adding Si and Nb, a small amount of ZrO2 and Si3N4 was detected along with the main phases in the TiZrCN structure.

Study on changes in electrical and switching characteristics of NPT-IGBT devices by fast neutron irradiation

We studied the irradiation effects of fast neutron generated by a 30 MeV cyclotron on the electrical and switching characteristics of NPT-IGBT devices. Fast neutron fluence ranges from 2.7 × 109 to 1.82 × 1013 n/cm2. Electrical characteristics of the IGBT device such as I–V, forward voltage drop and additionally switching characteristics of turn-on and -off were measured. As the neutron fluence increased, the device's threshold voltage decreased, the forward voltage drop increased significantly, and the turn-on and turn-off time became faster. In particular, the delay time of turn-on switching was improved by about 35% to a maximum of about 39.68 ns, and that of turn-off switching was also reduced by about 40%–84.89 ns, showing a faster switching.

IR Spectroscopy of Vacancy Clusters (Amber Centers) in CVD Diamonds Nanostructured by Fast Neutron Irradiation

We investigated the IR absorption spectra of CVD diamond damaged by fast neutrons (>0.1 MeV) with high fluences ranging from 1 × 1018 to 2 × 1019 cm−2 and annealed at temperatures of 200 °C to 1680 °C. After annealing above 1000 °C, the formation of “amber-centers” (ACs), associated with multivacancy clusters, is detected as deduced from the appearance of a strong absorption line at 4100 cm−1. Moreover, the concentration of the ACs in the irradiated diamond can be an order of magnitude higher than that observed previously in the darkest brown natural diamonds. A number of other absorption lines, including the H1b center at 4936 cm−1 (0.612 eV) and new lines at ~5700 cm−1 (0.706 eV) and 9320 cm−1 (1.155 eV) not reported before in the literature, are observed, and their intensity evolutions at annealing temperatures are documented. At the highest fluences, all the lines show reduced intensities and broadening and spectral shifts due to a very high defect concentration and partial amorphization. The obtained experimental data can be used for the analysis of defect generation, transformations and healing in irradiated synthetic and natural diamonds.

Exceptional structural and functional stability of Zr-doped REBaCuO tapes with respect to neutron irradiation and overheating

The impact of neutron irradiation on the properties of second-generation REBaCuO tapes was studied. The main aim of the present study was to identify the fast neutrons irradiation fluence threshold, φ th, at which the high-field critical current at low temperatures, I c (10 K, 8 T), starts degrading. Following up on our previous publication for low irradiation fluences, two new irradiation steps were added. Up to the last but one irradiation step, the T c in all samples followed a linear dependence on the fast neutrons irradiation fluence, T c(φ) ≈ T c(0) − τφ (τ being a numerical constant in units of K/1022 m−2 and φ in 1022 m−2). In parallel, I c (10 K, 8 T) continuously grew with φ up to the threshold fluence, φ th ≈ 3× to 4.3 × 1022 m−2. The last gradual irradiation by φ≈ 1.83 × 1022 m−2 brought a severe degradation both in T c and I c (10 K, 8 T) in most samples, irrespective of their irradiation history. This effect was attributed to radiation overheating. Annealing of pristine tapes in dilute Ar confirmed this scenario. Two of the SuperPower tapes, doped by Zr, appeared to be exceptionally stable against both types of overheating. The tape doped with 7.5% Zr, T c(φ) followed the linear dependence up to the highest cumulative fluence φ =6.16 × 1022 m−2, while the I c (10 K, 8 T) drop was several orders of magnitude lower than in the samples without Zr. TEM study found that the Zr-doped tapes survived the overheating during the last irradiation step in a crystalline form, while all other samples were amorphized.

Measurement of 6Li burn-up reaction rate using a single crystal CVD diamond detector under fast neutron irradiation environment

The study aimed to develop a technique for measuring the 6Li burn-up rate using a single crystal diamond (SCD) detector (SDD) made by chemical vapor deposition (CVD) with a thin lithium fluoride foil. The method relied on pulse shape discrimination (PSD) to separate pulses by nuclear reaction products of 6Li from pulses due to fast neutrons and gamma-rays.By applying the PSD method, the rectangular shape pulses induced by events occurred at the specific depth positions of the SCD, i.e., the incident surface, the ballistic center region (BCR), and the rear surface, were extracted. Thereafter, pulses occurred each specific depth position of the SCD were discriminated according to the pulse width.Due to a short range of nuclear reaction products in the SCD, pulses at the incident surface should be induced by both fast neutrons and nuclear reaction products, although pulses at the BCR are caused by fast neutron only. The study demonstrated that quantitative measurements of nuclear reaction products in the 6Li burn-up reaction under fast neutron irradiation can be achieved using only one SDD by analyzing event rates at the incident surface and in the BCR region.

Determination of toxicity and radioprotective properties of bacterial and fungal eumelanin pigments

Purpose Determination of the protective property of melanin, an organic polymer class consisting of phenolic and/or indolic compounds isolated from bacteria and fungi, against fast neutron radiation. To show that these melanin samples, which also have antioxidant and metal chelating properties, can be used as an active ingredient for a drug to be developed against neutrons used in nuclear research and medicine. Materials and methods Bacterial and fungal media were prepared, and melanin pigments were produced and isolated. For molecular characterization of pigments, bacterial genomic DNA extraction, 16S rDNA gene amplification processes, and fungal genomic DNA extraction, ITS1, and ITS4 Gene Regions amplification were performed. The DEL assay was implemented to determine the genotoxicity properties of bacterial and fungal melanin pigments. Samples were prepared in a pad measuring 10 ml volume (60 × 15 mm) at a concentration of 0.2–1 microgram in 1% agarose gel for radiation-absorbed dose measurements. Absorption measurements were made using 241Am-Be fast neutron source and Canberra brand NP series BF3 gaseous detector to determine the neutron radiation absorption capacity of all samples. The results obtained to determine the absorption degrees of melanin samples were compared with paraffin and normal concrete, which are widely used in neutron radiation shielding studies. Results Melanin pigments were obtained using different bacteria and fungi strains. Afterwards, the fast neutron radiation absorption capacity of these purified pigments were determined. Compared to reference samples, these pigments were found to have slightly lower radiation absorbing ability. In addition to these experiments, cytotoxicity tests were carried out using the Yeast DEL assay technique to evaluate the potential for use of these organic pigments in fields such as medicine and pharmacology. According to the results obtained from the tests, it was determined that these melanin samples did not have any toxic effects. Conclusion It was determined that these melanin samples have the potential to be used as a radioprotective drug active substance to protect the tissues and cells of people exposed to neutron radiation after a nuclear accident or nuclear war. Giving a drug that will be developed by using these active ingredients before or after people are exposed to a radiation environment can provide great benefits.

A chromosome 16 deletion conferring a high sucrose phenotype in soybean.

Sucrose in soybean seeds is desirable for many end-uses. Increased sucrose contents were discovered to associate with a chromosome 16 deletion resulting from fast neutron irradiation. Soybean is one of the most economically important crops in the United States. A primary end-use of soybean is for livestock feed. Therefore, genetic improvement of seed composition is one of the most important goals in soybean breeding programs. Sucrose is desired in animal feed due to its role as an easily digestible energy source. An elite soybean line was irradiated with fast neutrons and the seed from plants were screened for altered seed composition with near-infrared spectroscopy (NIR). One mutant line, G15FN-54, was found to have higher sucrose content (8-9%) than the parental line (5-6%). Comparative genomic hybridization (CGH) revealed three large deletions on chromosomes (Chrs) 10, 13, and 16 in the mutant, which were confirmed through whole genome sequencing (WGS). A bi-parental population derived from the mutant G15FN-54 and the cultivar Benning was developed to conduct a bulked segregant analysis (BSA) with SoySNP50K BeadChips, revealing that the deletion on Chr 16 might be responsible for the altered phenotype. The mapping result using the bi-parental population confirmed that the deletion on Chr 16 conferred elevated sucrose content and a total of 21 genes are located within this Chr 16 deletion. NIR and high-pressure liquid chromatography (HPLC) were used to confirm the stability of the phenotype across generations in the bi-parental population. The mutation will be useful to understand the genetic control of soybean seed sucrose content.