[en] Pressurizer Safety Valve(PSV) is designed to prevent reactor overpressure during design basis accidents. For Korean plants, the PSVs have been assumed to open within ±1% tolerance of set pressure and the tolerance is verified with an in-service testing in accordance with technical specification. In the licensing safety analyses for overpressure protection capability of the Korean plants, test equipment (auxiliary lift device) uncertainty of +1% has been simply added to the set pressure as a bias (penalty) for PSV opening. However, PSV set pressure test results so far shows a probability distribution and thus the tolerance should be determined on the basis of the test results not by a bias since statistically all kinds of physical phenomena have a non-zero probability to go beyond certain fixed limits by faults. A new statistical approach of determining PSV test tolerances by elimination of the test equipment uncertainty and the effects on the licensing safety analyses and plant designs are discussed

No abstract available

[en] A study on the valve opening time in rupture disc type S/R valve for the high pressure vessel is necessitated to assure the safety and relief of the high pressure vessel. So, in the present study, an experimental study by using a shock tube facility with dimensional analysis is performed to estimate the effects of diaphragm curvature radius, pressure ratio and the depth of the groove on the valve opening time. As a result, it is found that the radius of curvature of the rupture disc becomes smaller, the thickness of the rupture disc is thinner, the ultimate strength of the rupture disc is smaller for the same conditions, the valve opening time is shorter, and, the radius of curvature and the ultimate strength of the rupture disc for the same conditions are smaller, the maximum pressure rise caused by the coalescences of the compression wave is smaller

No abstract available

[en] Abstract Bibliography related to the design of ceramic floorings, their historic progression and current background is extensive. The investment in the research of new materials formulations, both for ceramic supports, glazes and dyes has been intensive in the last decades, in order to maximize industrial productivity. Nevertheless, there are very few works engaged with the peculiarities of the geometric and structural configuration of ceramic products, where the back relief of the tile could have an essential role. In this article, we report the development of back relief's along time, according to the technological determinants of the sector. Then, we analyze the current situation of ceramic back relief's, as well as their development opportunities with regard to new design factors, namely, the new sales market, the new environmental requirements, and the accomplishment of the international regulations in the matter of quality production and building safety. Finally, we report the new approaches undertaken in the ceramic cluster of Castellon (Spain), with the collaboration of the Universidad Politecnica de Valencia, based on computer aided design. (Author)

[en] This paper describes a nuclear reactor control system for controlling the reactivity of the core of a nuclear reactor. It includes a control gas having a high neutron cross-section; a first tank containing a first supply of the control gas; a first conduit providing a first fluid passage extending into the core, the first conduit being operatively connected to communicate with the first tank; a first valve operatively connected to regulate the flow of the control gas between the first tank and the first conduit; a second conduit concentrically disposed around the first conduit such that a second fluid passage is defined between the outer surface of the first conduit and the inner surface of the second conduit; a second tank containing a second supply of the control gas, the second tank being operatively connected to communicate with the second fluid passage; a second supply valve operatively connected to regulate the flow of the control gas between the second tank and the second fluid passage

[en] In this article author made conclusion that at determination ofcontemporary maximal intensity it is possible use of intensity of seismicinfluence determined with the help of pale-seismological method

[en] The Savannah River Site operates a Relief Valve Repair Shop certified by the National Board of Pressure Vessel Inspectors to NB-23, The National Board Inspection Code. Local maintenance forces perform inspection, testing, and repair of approximately 1200 spring-operated relief valves (SORV) each year as the valves are cycled in from the field. The Site now has over 7000 certified test records in the Computerized Maintenance Management System (CMMS); a summary of that data is presented in this paper. In previous papers, several statistical techniques were used to investigate failure on demand and failure rates including a quantal response method for predicting the failure probability as a function of time in service. The non-conservative failure mode for SORV is commonly termed 'stuck shut'; industry defined as the valve opening at greater than or equal to 1.5 times the cold set pressure. Actual time to failure is typically not known, only that failure occurred some time since the last proof test (censored data). This paper attempts to validate the assumptions underlying the statistical lifetime prediction results using Monte Carlo simulation. It employs an aging model for lift pressure as a function of set pressure, valve manufacturer, and a time-related aging effect. This paper attempts to answer two questions: (1) what is the predicted failure rate over the chosen maintenance/ inspection interval; and do we understand aging sufficient enough to estimate risk when basing proof test intervals on proof test results?

[en] Modular Design is a new design method which is rapidly developed in the world. The basic concept of modular design was introduced in this paper. The modular construction of pressurizer pilot operated safety valve was analyzed and divided into several independent modules. The design proposal of the pilot operated safety valve localization production was studied based on the former modular analysis for the nuclear auxiliary system such as RRA and RCV. (authors)

[en] In this study, thermal and structural analyses are carried out to design a crankcase relief valve for marine diesel engines that are capable of preventing the flame and sudden pressure rise of the crankcase. Numerical analyses are performed using a commercial program (ANSYS), and by applying the pressure change according to the time in the crankcase. In order to ensure the normal operation of the part under high pressure, thermal and structural analyses of five types of flame traps are performed to determine the shape using the maximum stress and minimum temperature. Based on the numerical analysis results, the maze-type valve disk was manufactured. The explosion phenomenon was compared before and after mounting the relief valve. As a result, the effectiveness of the relief valve was confirmed by the prevention of the external discharge of the flame while discharging the excess pressure during an explosion.