Swelling of safety rod guide tubes in nonuniform fields of temperature and irradiation

AbstractSafety rod guide tubes are important components of fast reactor cores for ensuring safe reactor operation. Their failure or considerable changes of their size may lead to safety rod wedging that is unacceptable. Two guide tubes, one each from BN-350 and BOR-60, were examined post-irradiation to determine the reasons for their deformation and loss of functionality. These tubes were constructed from high-nickel alloy EP-150 and austenitic 18Cr9Ni, respectively.It is found that various forms of deformation of safety rod guide tubes occur due to non-uniform swelling along the tube height, perimeter and across-wall thickness. The swelling gradients can lead to bowing and ovality, and can be accompanied by significant internal stresses within the tube material. The latter can lead to size reduction of guide tube dimension in some directions due to irradiation creep. High levels of swelling-induced residual stresses, in combination with a swelling-induced embrittlement of the tube material, can lead to the tube failure even in the absence of any external loading

When is a face a face? Schematic faces, emotion, attention and the N170

Emotional facial expressions provide important non-verbal cues as to the imminent behavioural intentions of a second party. Hence, within emotion science the processing of faces (emotional or otherwise) has been at the forefront of research. Notably, however, such research has led to a number of debates including the ecological validity of utilising schematic faces in emotion research, and the face-selectively of N170. In order to investigate these issues, we explored the extent to which N170 is modulated by schematic faces, emotional expression and/or selective attention. Eighteen participants completed a three-stimulus oddball paradigm with two scrambled faces as the target and standard stimuli (counter-balanced across participants), and schematic angry, happy and neutral faces as the oddball stimuli. Results revealed that the magnitude of the N170 associated with the target stimulus was: (i) significantly greater than that elicited by the standard stimulus, (ii) comparable with the N170 elicited by the neutral and happy schematic face stimuli, and (iii) significantly reduced compared to the N170 elicited by the angry schematic face stimulus. These findings extend current literature by demonstrating N170 can be modulated by events other than those associated with structural face encoding; i.e. here, the act of labelling a stimulus a ‘target’ to attend to modulated the N170 response. Additionally, the observation that schematic faces demonstrate similar N170 responses to those recorded for real faces and, akin to real faces, angry schematic faces demonstrated heightened N170 responses, suggests caution should be taken before disregarding schematic facial stimuli in emotion processing research per se

Study of materials for reactors employing molten fluoride salts or PB-BI coolant using an electron irradiation test facility

Overview of results obtained within the framework of the STCU Project #294 is givenНаведено огляд результатів, отриманих в рамках проекту УНТЦ № 294.Приведен обзор результатов, полученных в рамках проекта УНТЦ № 29

Radiation resistance of copper alloys at high exposure levels

Copper alloys are currently being considered for high heat flux applications in fusion power devices. A review is presented of the results of two separate series of experiments on the radiation response of copper and copper alloys. One of these involved pure copper and boron-doped copper in the ORR mixed spectrum reactor. The other series included pure copper and a wide array of copper alloys irradiated in the FFTF fast reactor 16 refs., 13 figs

Can a shift in the purchase of local foods by Supplemental Nutrition Assistance Program (SNAP) recipients impact the local economy?

In recent years, several initiatives have sought to encourage redemption of food assistance benefits at direct-to-consumer (DTC) market venues such as community supported agriculture programs and farmers' markets in the USA, with the dual goal of increasing access to healthy foods for low-income families and sales of locally-grown foods for farmers. Proponents of these interventions assert that these programs have a positive impact on local economies yet there is limited evidence to validate this argument. This research project used a customized input-output model to simulate potential economic impacts of programs and policies that enable Supplemental Nutrition Assistance Program (SNAP) recipients to shift purchases from traditional food retailers to DTC venues in four states. Two different scenarios were explored: (1) increased outreach to low-income consumers and (2) financial support for using SNAP benefits at DTC market channels. We found a positive, though modest, economic impact at the state level under both scenarios when accounting for (a) business losses in the food retail and wholesale sectors, (b) a shift in acreage from commodity to specialty crops and (c) the cost to taxpayers. Since most of the increased economic activity would be in the produce farming sector, we discuss the opportunities and challenges for this sector along with potential policy implications

Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at s√ = 13 TeV with the ATLAS detector

A measurement of the top-quark mass (mt) in the tt¯ → lepton + jets channel is presented, with an experimental technique which exploits semileptonic decays of b-hadrons produced in the top-quark decay chain. The distribution of the invariant mass mℓμ of the lepton, ℓ (with ℓ = e, μ), from the W-boson decay and the muon, μ, originating from the b-hadron decay is reconstructed, and a binned-template profile likelihood fit is performed to extract mt. The measurement is based on data corresponding to an integrated luminosity of 36.1 fb−1 of s√ = 13 TeV pp collisions provided by the Large Hadron Collider and recorded by the ATLAS detector. The measured value of the top-quark mass is mt = 174.41 ± 0.39 (stat.) ± 0.66 (syst.) ± 0.25 (recoil) GeV, where the third uncertainty arises from changing the PYTHIA8 parton shower gluon-recoil scheme, used in top-quark decays, to a recently developed setup

Search for resonances decaying into photon pairs in 139 fb−1 of pp collisions at √s = 13 TeV with the ATLAS detector

Searches for new resonances in the diphoton final state, with spin 0 as predicted by theories with an extended Higgs sector and with spin 2 using a warped extra-dimension benchmark model, are presented using 139 fb−1 of √s = 13 TeV pp collision data collected by the ATLAS experiment at the LHC. No significant deviation from the Standard Model is observed and upper limits are placed on the production cross-section times branching ratio to two photons as a function of the resonance mass

Search for single vector-like B quark production and decay via B → bH(b¯b) in pp collisions at √s = 13 TeV with the ATLAS detector

A search is presented for single production of a vector-like B quark decaying into a Standard Model b-quark and a Standard Model Higgs boson, which decays into a b¯b pair. The search is carried out in 139 fb−1 of √s = 13 TeV proton-proton collision data collected by the ATLAS detector at the LHC between 2015 and 2018. No significant deviation from the Standard Model background prediction is observed, and mass-dependent exclusion limits at the 95% confidence level are set on the resonance production cross-section in several theoretical scenarios determined by the couplings cW, cZ and cH between the B quark and the Standard Model W, Z and Higgs bosons, respectively. For a vector-like B occurring as an isospin singlet, the search excludes values of cW greater than 0.45 for a B resonance mass (mB) between 1.0 and 1.2 TeV. For 1.2 TeV < mB < 2.0 TeV, cW values larger than 0.50–0.65 are excluded. If the B occurs as part of a (B, Y) doublet, the smallest excluded cZ coupling values range between 0.3 and 0.5 across the investigated resonance mass range 1.0 TeV < mB < 2.0 TeV

Searches for exclusive Higgs boson decays into D⁎γ and Z boson decays into D0γ and Ks0γ in pp collisions at √s = 13 TeV with the ATLAS detector

Searches for exclusive decays of the Higgs boson into D⁎γ and of the Z boson into D0γ and Ks0γ can probe flavour-violating Higgs boson and Z boson couplings to light quarks. Searches for these decays are performed with a pp collision data sample corresponding to an integrated luminosity of 136.3 fb−1 collected at s=13TeV between 2016–2018 with the ATLAS detector at the CERN Large Hadron Collider. In the D⁎γ and D0γ channels, the observed (expected) 95% confidence-level upper limits on the respective branching fractions are B(H→D⁎γ)&lt;1.0(1.2)×10−3, B(Z→D0γ)&lt;4.0(3.4)×10−6, while the corresponding results in the Ks0γ channel are B(Z→Ks0γ)&lt;3.1(3.0)×10−6

Measurement of vector boson production cross sections and their ratios using pp collisions at √s = 13.6 TeV with the ATLAS detector

Abstract available from publisher's website