[en] Under European regional TC project RER/4/011, IAEA and VUJE Training centre organized a workshop on On-line Testing of Nuclear Power Plant Temperature and Pressure Instrumentation and Other Critical Plant Equipment in Trnava, Slovak Republic, from 25 to 29 May 1998. The objective of the workshop was to review the state-of-the-art in NPP instrumentation, cover typical instrumentation problems and solutions, describe technical and regulatory requirements for verifying the performance of nuclear power plant instrumentation, describe new methods developed and applied in NPPs for on-line verification and performance of instrumentation and present new techniques using existing instrumentation to identify the on-set problems in the plant electrical, mechanical and thermal hydraulic systems. Particular emphasis was placed on temperature measurements by Resistance Temperature Detectors (RTDs) and thermocouples and pressure measurements using motion-balanced and forced-balanced pressure transmitters. This proceedings includes papers presented by the invited speakers and the participants each with an abstract as wells as a summary of the Round-Table discussions

[en] The mission of the World Association of Nuclear Operators (WANO) is highlighted, and WANO's Peer Review programme is described. At the Dukovany nuclear power plant, a Peer Review was undertaken in December 1997. The results gave evidence of a good level of safety, reliability and culture of operation of the plant. (P.A.)

[en] Exhaust ducts 2F and 3F of Research Building No.4 was renewed by replacing old steel ducts lining with vinyl chloride to hard type vinyl chloride ducts. Following the preparation works from July 1997, the construction was started at the beginning of December 1997 and finished at the end of April 1998. Before the construction, a working group consisting of the facility manager, the manager for radiation protection and the representative users of the facility was organized in order to discuss various things concerning the construction such as plans, specifications and so on. All of the management works during construction was done by the working group. In this paper, the renewal of exhaust ducts inside the radiation controlled area (Research Building No.4) is described. (author)

[en] The Ohio State University Nuclear Reactor Laboratory (OSU NRL) participated in the Department of Energy (DOE) grant program commonly denoted as the University Reactor Instrumentation (URI) program from the period September 1990 through August 1995, after which funding was terminated on a programmatic basis by DOE. This program provided funding support for acquisition of capital equipment targeted for facility upgrades and improvements, including modernizing reactor systems and instrumentation, improvements in research and instructional capabilities, and infrastructure enhancements. The staff of the OSU NRL submitted five grant applications during this period, all of which were funded either partially or in their entirety. This report will provide an overview of the activities carried out under these grants and assess their impact on the OSU NRL facilities

[en] The use of software-based systems in safety-important roles on nuclear power plants is a steadily growing trend, now almost without exception for new plant designs and increasingly evident for the replacement of obsolescent systems in older plants. This trend is fueled by more sophisticated functionality per unit of cost which the technology affords, with the economic attractiveness of enabling higher plant outputs whilst acceptably preserving (even, arguably, enhancing) plant safety. It would be of obvious value to both supplier and user if international regulatory agreement could be established so to the constituents of an acceptable safety-case demonstration for a computer system in a safety-important role on a nuclear power power plant. Representatives of the nuclear regulatory authorities from Canada (Atomic Energy Control Board), France (Direction de la Surete des Installations Nucleaires/Institut de Protection et de Surete Nucleaire), United Kingdom (Nuclear Installations Inspectorate) and United States (Nuclear Regulatory Commission) have met to compare regulatory approaches, experiences and learning in this area. A body of consensus has been successfully developed and presented in a report with supporting background information to enable an appreciation to be gained of the regulatory systems applying in the four countries. While the report should not be regarded as official regulatory guidance, it nevertheless does serve to identify the basic set of commonly agreed demonstration elements, compatible with the individual countries' regulatory requirements, which all four regulatory bodies would expect to see addressed in a safety case for a software-based system intended for safety-important usage on a nuclear power plant. The purpose of this paper is to raise awareness of the consensus report and the guidance it provides. (author)

[en] Digital technology is being applied to control systems in nuclear power plants. Especially in Japanese BWRs, control systems are being digitized both in constructing plant and in retrofit of operating plants. Digital technology has many advantages compared with analog technology. However, its high performance and flexibility may result in too complicated software structure, which will cause long design time and long testing time and increase cost. In introduction of digital technology, it is most important to restrict unnecessary flexibility of software. The function of control systems can be divided in standard part and variable part. Standard function may be common to every plant while variable function should be designed for each plant. Even in current design, standard design is preserved to be reused in next application. However, this design approach is not always effective because standard function may be changed by customer and nothing is considered for variable part even if it is large. To keep reliability and reduce cost by software reuse, Toshiba adopts modular design of control software, where standard part is designed as a set of standard functional modules and variable function is designed as a complex of standard functional modules and plant unique modules. Toshiba firstly applied modular design method to fuel handling machine control system. In this application the design work has been reduced to 30 percent by reusing of functional module which was first developed in former applications. This remarkable reduction of design work has enhanced reliability with less cost. In addition, software, has been produced and tested according to the functional module. These qualified software modules will be applied to next system and will realize highest reliability and least cost. Toshiba is now planning the application of this modular design method for every digital control system. (author)

[en] Since foundation of Nuclear Power Plant Research Institute (NPPRI) in 1977, the department of diagnostics has been dealt with problems related to the theoretical, practical and organizatory questions of operational diagnostics connected with PWR type nuclear components. This department acts directly in locality of NPP Jaslovske Bohunice, but there are performances for all NPP in Slovak or Czech Republic (Dukovany, Mochovce, and Temelin). Besides direct services and achievements for NPP there exist advisory, experts and research activities for the government and supervising authorities, too. In 1985, NPPRI began systematically construct and verify technical means for operational diagnostics of main circulating pumps (MCP) with good results, based on own rich practical experiences and contacts with organisations abroad. In recent years NPPRI as one of recognised qualified and authorised institutions in Slovak Republic has begun to develop a new generation of diagnostic systems for NPP on high technical level but with lower procuring costs in comparison with western countries products. This contribution deals with four following types of diagnostic systems which were not only developed but also delivered and installed on Slovak and Czech nuclear units: - Loose part monitoring system (LPMS), - Humidity monitoring system (HUMON), - Reactor coolant pumps monitoring system (RCPMS), - Primary circuit vibration monitoring system (VMS). Main features of new generation from middle of 1990's of these systems are described in this paper and operational experiences with them too. (author)

No abstract available

[en] The Nuclear Reactor Program at North Carolina State University initiated an upgrade program at the NCSU PULSTAR Reactor in 1990. The originally supplied instrumentation has been replaced with solid-state and current technology equipment. The financial assistance from the US Department of Energy has been the primary source of support. This is the final report for the Instrumentation Upgrade

[en] In order to establish a method of probabilistic safety analysis for passive safety features, the event-tree (E/T) of ULOF accident sequences in the early stage of accident progression was constructed for an 600 MWe LMFBR model plant equipped with passive safety features such as Self Actuated Shutdown System (SASS) and Gas Expansion Modules (GEM). The development of this E/T was based on the results of some ULOF accident sequence analyses considering the effect of GEM. Even if the negative reactivity introduced by the GEM could not be enough to terminate the accident progression completely, there is some possibility to make the accident progression slower and to terminate the accident by manual reactor scram procedures with successfully starting of the pony motors in primary coolant loops. This accident mitigation pass was introduced into the E/T. Using this E/T and some fault tree (F/T) models related to the reactor shutdown function and the pony motor, the accident sequences were quantified and the conditional probability of coolant boiling when ULOF accidents occur was evaluated. Though the evaluation was in a preliminary stage, the conditional probability of coolant boiling when ULOF accidents occur was evaluated in the order of 10^-3 due to the effect of the passive safety features such as GEM and SASS. Through the preliminary evaluation, system analysis models such as E/T and F/Ts for ULOF sequence with considering the effect of passive safety features were developed. (author)