Investigation on hydraulic-mechanical properties in bentonite-sand mixture with consideration of salinity water

Bentonite with fine components much such as extremely expansive soil has been commonly required as buffer/backfill materials in order to prevent seepage for construction of further deep geologicalrepository for disposal of high-level radioactive waste (i.e. HLW). The buffer received significant hydromechanical efforts from host rock at underground environment. While the construction/maintenance with long-time operation of a repository, it was predicted that high compacted bentonite will be progressively hydration due to pore water flow or infiltrated from surrounding host rock. The purpose of this study is to establish the connection among the basic mechanical properties, soil retention characters and chemical couple properties under unsaturated condition and saturated conditions for a bentonite-sand mixture. This conducted out some testing programs, which are soil-water characteristic curve test, unconfined compression test, creep test and triaxial compression test for unsaturated sodium bentonite sand mixture and saturated bentonite sand mixture. In addition, the influence of salinity water on mechanical properties is considered with comparison to saturated bentonite sand mixture subjected to swelled due to distilled water

Behavior of compacted Ca-bentonite subjected to HMC loading: observations and interpretation

This study presents result of HMC experimental test and discussions of chemical effort in Cabentonite. SWCC test, swelling pressure test and unconfined compression test as hydro-mechanical-chemical (HMC) test were applied to Cabentonite-sand mixture. Na-type bentonite has been studied to predict safety and confidence for artificial barrier layer consist of bentonite that many experimental research reports are represented, and can offer technology advanced comprehensive performance due to mathematical simulation models associated to physical parameters on thermal-hydration-mechanical-chemical properties. This study proposed a significant property for calcium bentonite to relate evaluating safety in radioactive waste disposal system, which emphasised much influence of suction and salinity chloride to hydration-mechanical behaviour for Calcium bentonite

Experimental verification of real-time gamma-ray energy spectrum and dose monitor

The purpose of this study is to develop a portable monitor that can measure the energy spectrum and dose of gamma-rays simultaneously in real time for the benefit of medical staff who must work in clinical radiation environments. For this purpose, we have developed a prototype monitor using a CsI (Tl) scintillator combined with a multi-pixel photon counter (MPPC). For real-time measurement, we employed an improved sequential Bayesian estimation (k-α method) to convert the measured pulse height spectrum into an energy spectrum. Then we confirmed that reconstruction of the energy spectrum and dose estimation could simultaneously be carried out in real time by the k-α method in a radiation field composed of mixed standard gamma-ray sources. In this study, we carried out measurements in a background gamma-ray field to confirm applicability of the prototype monitor to the weakest type of radiation field. In addition, we conducted measurements in front of a nuclear fuel storage room (∼2 μSv/h) in the authors’ laboratory to evaluate practicality of the monitor for measuring fields with a complex energy spectrum. As a result, it was found that the dose could be estimated in about 20 s after start of measurements even in the background field. For the energy spectrum, it was instantly reconstructed within 60 s in front of the fuel storage room. On the other hand, it could successfully be estimated within 10 min in the background gamma-ray field. Currently, the convergence of the energy spectrum is determined visually from time dependent change of the spectrum and dose. As a next step, we will attempt to develop a more quantitative procedure for determining the convergence

Clinical practice competencies for standard critical care nursing: consensus statement based on a systematic review and Delphi survey

Objectives A clear development process and scientifically validated clinical practice competencies in standard critical care nursing (SCCN) have not yet been developed in Japan. Thus, this study aimed to develop a consensus-based set of SCCN competencies to provide a framework for critical care nursing education, training and evaluation.Design Multistep, modified Delphi study (a systematic review, focus group interviews, a three-round web-based Delphi survey and an external validation process).Participants A systematic review of 23 studies, focus group interviews by 12 experts, a Delphi survey by 239 critical care experts (physicians, nurses and physical therapists) and an external validation by 5 experts (physicians and nurses).Results A systematic review identified 685 unique competencies. The focus group interviews resulted in the addition of 3 performance indicator items, a synthesis of 2 subdomains and 10 elements. Of the 239 participants, 218 (91.2%), 209 (98.9%) and 201 (96.2%) responded in rounds 1, 2 and 3 of the Delphi survey, respectively. After round 3, 57 items were below the consensus level and were removed in the final round. External validation process feedback was received from experts after two revisions to ensure that the final competencies were valid, applicable, useful and clear. The final set of competencies was classified into 6 domains, 26 subdomains, 99 elements and 525 performance indicators.Conclusions This study found a set of SCCN competencies after a multistep, modified Delphi study. The results of this study are robust, and the competency framework can be used in multiple areas to improve clinical practice, including the assessment, training and certification of standard critical care nurses