In 2008, Nuclear and Industrial Safety Agency (NISA) (currently integrated to the Nuclear Regulatory Authority) launched a project to develop a soundness assessment method for concrete members subject to a radiation environment. Presently, the soundness of concrete members subject to radiation is evaluated based on whether the predicted fast neutron fluence and gamma-ray dose values are lower than specific reference values in Japan, which are 1×10 20 n/cm 2 and 2×10 5 kGy, respectively. These reference values were determined based on report by Hilsdorf et al. This project begins by reviewing Hilsdorf et al.'s report, and we find that the scientific evidence for the current reference values is weak. We thus conclude that new experimental research is required to assess the current reference values and to propose a new alternative soundness assessment procedure if needed. We quantitatively evaluated the influence of neutrons, gammarays, and the resultant heating and drying processes on the strength of concrete as well as their underlying mechanisms. The irradiation experiments confirmed the degradation mechanism of concrete due to neutron irradiation. The main reason for this degradation is the metamictization of rock-forming minerals, which, in turn, leads to aggregate expansion. Due to aggregate expansion, cracks around aggregates form, which reduce the compressive strength and Young's modulus of concrete. Among the rock-forming minerals, α-quartz is the most sensitive to neutron radiation.60 Co gamma-ray irradiation experiments demonstrated that concrete strength increased as the gamma-ray dose and gammaray flux does not have a dose-rate impact on the first radiolysis of evaporable water in cement paste within the present study. The effect of gamma-ray irradiation on the properties of concrete is equivalent to that of heating and drying. Concrete strength alteration due to heating and drying is attributed to the colloidal and porous nature of hardened cement paste and crack formation around the aggregate due to a mismatch in the volume changes of the mortar and aggregate. In addition, a numerical analysis code called DEVICE (Damage EValuation for Irradiated ConcretE) is developed to harness knowledge obtained from concrete samples to predict the distribution of the physical properties in concrete members and their changes over time. From these fundamental studies, we propose a new soundness assessment procedure for concrete members subject to radiation. We also recommend a new radiation-induced strength-degradation reference value of 1×10 19 n/cm 2 for fast neutron.

In this paper, we consider phenomenology of a model with an L µ − L τ gauge symmetry. Since the muon couples to the L µ − L τ gauge boson (called Z boson), its contribution to the muon anomalous magnetic moment (muon g-2) can account for the discrepancy between the standard model prediction and the experimental measurements. On the other hand, the Z boson does not interact with the electron and quarks, and hence there are no strong constraints from collider experiments even if the Z boson mass is of the order of the electroweak scale. We show an allowed region of a parameter space in the L µ − L τ symmetric model, taking into account consistency with the electroweak precision measurements as well as the muon g-2. We study the Large Hadron Collider (LHC) phenomenology, and show that the current and future data would probe the interesting parameter space for this model.

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Concrete aggregate identified as "meta-chert" was irradiated with gamma-rays and neutrons. To identify the volume expansion of the aggregate under neutron irradiation, the following analyses were performed for pristine and irradiated α-quartz and metachert: X-ray diffraction (XRD)/Rietveld analysis, dimension change, water pycnometry, He-pycnometry, light optical microscopy (LOM), and scanning electron microscopy (SEM). From the difference of volume expansion observed from dimension change and water/helium pycnometry, the crack opening inside the aggregate subjected to irradiation was elucidated, and this was confirmed by LOM and SEM analysis. The crack contribution to the expansion of the aggregate was significant for neutron fluence > 6.99 × 10 19 n/cm 2 , for E ≥ 0.01 MeV. Based on the XRD analysis, changes in lattice parameters were identified and the cell volume expansion was compared with the data obtained by helium pycnometry. Based on the density change calculation and phase calculation data, the density of X-ray amorphous phase was consistent with that of expanded crystal α-quartz.

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