[en] The Large High Altitude Air Shower Observatory (LHAASO) is a multipurpose project with a complex detector array for high energy gamma ray and cosmic ray detection. The array of 1 km² is composed of five types of detectors to measure shower arrival direction, total number of secondary particles, muon content, Cherenkov image and high energy gamma rays near shower core, respectively. The main scientific goals are (1) searching for galactic cosmic ray origins by extensive spectroscopy investigations of gamma ray sources above 30 TeV; (2) all sky survey for gamma ray sources at energies higher than 300 GeV; (3) energy spectrum and composition measurements of cosmic rays over a wide range covering knees with fixed energy scale and known fluxes for all species at the low energy end. In this paper, the progress on relevant detector developments is reported, including constructions of prototype detectors at Tibet site and coincidence operation with the ARGO-YBJ resistive plat chamber full coverage array at 4300 m a.s.l. The energy spectrum of cosmic ray hydrogen and Helium nuclei up to 0.8 PeV is reported as the first piece of physics measurements by the LHAASO experiment

[en] Gamma ray source detection above 30 TeV is an encouraging approach for finding galactic cosmic ray sources. All sky survey for gamma ray sources using wide field of view detector is essential for population accumulation for various types of sources above 100 GeV. In order to target those goals, a large air shower particle detector array of 1 km² (the LHAASO project) at 4300 m a. s. l. is proposed. By adding two MagicIItype telescopes in the array as proposed, LHAASO will be enhanced in source morphologic investigation power. The proposed array will be utilized also for energy spectrum measurement for individual cosmic ray species above 30 TeV. By re-configuring the wide field of view telescopes into fluorescence light detector array, the aperture of the detector array can be enlarged to cover an energy region above 100 PeV where the second knee is located. Cosmic ray spectrum and composition will be measured in order to transfer an energy scale to ultra high energy cosmic ray experiments. (authors)

[en] Highlights: • Two dimensional module is developed to analyze integrity of lower head. • Verification step has been done to evaluate feasibility of new module. • The new module is applied to simulate large-scale advanced PWR. • Importance of 2-D approach is clearly quantified. • Major parameters affecting vessel temperature distribution are identified. - Abstract: In order to evaluate the safety margin during a postulated severe accident, a module named ASAP-2D (Accident Simulation on Pressure vessel-2 Dimensional), which can be implemented into the severe accident simulation codes (such as ATHLET-CD), is developed in Shanghai Jiao Tong University. Based on two-dimensional spherical coordinates, heat conduction equation for transient state is solved implicitly. Together with solid vessel thickness, heat flux distribution and heat transfer coefficient at outer vessel surface are obtained. Heat transfer regime when critical heat flux has been exceeded (POST-CHF regime) could be simulated in the code, and the transition behavior of boiling crisis (from spatial and temporal points of view) can be predicted. The module is verified against a one-dimensional analytical solution with uniform heat flux distribution, and afterwards this module is applied to the benchmark illustrated in NUREG/CR-6849. Benchmark calculation indicates that maximum heat flux at outer surface of RPV could be around 20% lower than that of at inner surface due to two-dimensional heat conduction. Then a preliminary analysis is performed on the integrity of the reactor vessel for which the geometric parameters and boundary conditions are derived from a large scale advanced pressurized water reactor. Results indicate that heat flux remains lower than critical heat flux. Sensitivity analysis indicates that outer heat flux distribution is more sensitive to input heat flux distribution and the transition boiling correlation than mass flow rate in external reactor vessel cooling (ERVC) channel, and the correlation for molten vessel and ERVC coolant inlet temperature. According to the results achieved, the new developed module shows good applicability to simulate the pressure vessel behavior during melt pool formation. Thus it can be applied for the future study of the severe accidents relating to lower head integrity

[en] A parton model based on perturbative QCD is developed for the description of ultra-high energy interaction between cosmic rays and air nuclei. A LLA QCD calculation of jet production cross sections in proton-proton scattering and a hadronization scheme based on independent fragmentation model are presented. A number of parameters in the hadronization scheme are so selected that the basic features of hadronic production in e⁺e^- collision covering C. M. energy region from 14 GeV to 91 GeV can be reproduced. A Monte Carlo generator is constructed to reproduce the basic characteristics of proton-antiproton scattering in the C. M. energy region from 60 to 1800 GeV and to extrapolate smoothly to ultra-high energy region extending to 22 TeV

[en] In this review, I will report progress in UHE neutrino search using existing experiments and status of constructing detectors. Physics relevant to UHE neutrinos are updated as well

[en] The method of plasma density control by gas puffing feedback and experimental results in the HL-1 device are given. Effective control of the density has been fulfilled. The drawbacks of some feedback patterns and system are discussed

[en] A hypothesis of regarding injecting test as 'anti-pumping' test is presented, and pumping test's 'match line method' is used to process data of injecting test. Accurate hydrogeologic parameters can be obtained by injecting test in the sandstone uranium deposits with low permeability and small pumping volume. Taking injecting test in a uranium deposit of Xinjiang for example, the hydrogeologic parameters of main ore-bearing aquifer were calculated by using the 'anti-pumping' hypothesis. Results calculated by the 'anti-pumping' hypothesis were compared with results calculated by water level recovery method. The results show that it is feasible to use 'anti-pumping' hypothesis to calculate the hydrogeologic parameters of main ore-bearing aquifer. (authors)

[en] A Monte Carlo generator of Chou-Yang model to describe proton-proton soft scattering is developed based on pp NSD scattering data and the subtraction of the contribution due to hard scattering. This generator can be used for the description of soft hadronic NSD proton-proton interactions from 26 GeV to 22 TeV. Major experimental results observed on colliders are reproduced reasonably by using the generator combined with the calculation of large p_T jet production and hadronization. A decrease of inelasticity with the increase of energy is predicted

[en] Cosmic Ray Tau Neutrino Telescopes (CRTNT) for sub-EeV cosmic ray measurement is discussed. Performances of a stereoscope configuration with a tower of telescopes plus two side-triggers are studied. This is done by using a detailed detector simulation driven by Corsika. Detector aperture as a function of shower energy above 10¹⁷ eV is calculated. Event rate of about 20k per year for the second knee measurement is estimated. Event rate for cross calibration with detectors working on higher energy range is also estimated. Different configurations of the detectors are tried for optimization. (authors)

[en] [Background] Uncertainty exists in melt pool parameters when postulated severe accident occurs in reactor, and heat flux distribution obtained by two-layer or three-layer melt pool configuration would vary from each other, hence it is necessary to analyze the uncertainty of in vessel retention (IVR) in different configurations. [Purpose] This study aims to investigate quantization uncertainty brought by three-layer configuration. [Methods] First of all, the self-developed code SPIRE was employed to verify with references and analyze the uncertainty of IVR in three-layer melt pool configuration based on core damage frequency (CDF). The input parameters were obtained according to the simulation results of accident scenarios. Then the three-layer melt pool configuration results were compared with that of two-layer melt pool configuration. Finally, uncertainty analysis was carried out based on Monte Carlo sampling and sensitive analysis. [Result] Compared with the two-layer melt pool configuration results, the safety margin at bottom of melt was decreased notably whilst safety margin at top of ceramic layer was increased. In 125000 cases generated by sampling, conditional failure probability in two-layer condition is 0, while in three-layer condition is 7.11 × 10^-5 (failure occurred in light metallic layer). [Conclusion] Sensitivity analysis showed that, within the scope of this study, the probability distribution for input parameters had little influence on the result; conditional failure probability was notably affected by the uranium oxidation fraction; melt fraction of core had certainty influence on safety margin at top of ceramic layer. (authors)