Software for computers in the safety systems of nuclear power stations

2001 ◽  
1983 ◽  
Author(s):  
Peter Doyle ◽  
Lothar Schroeder ◽  
Stephen Brewer
Keyword(s):  

2021 ◽  
pp. 1-18
Author(s):  
Ilina Cenevska

Abstract This case comment explores the relationship between two intertwined objectives – ensuring security of electricity supply and environmental protection – in the context of the judgment of the Court of Justice of the European Union in Inter-Environnement Wallonie ASBL and Bond Beter Leefmilieu Vlaanderen ASBL v. Conseil des ministres. The analysis focuses on the application of the Environmental Impact Assessment Directive and the Habitats Directive to the facts of the case, which concerns the extension by a ten-year period of the operation of two Belgian nuclear power stations (Doel 1 and Doel 2) as part of a national energy policy strategy to ensure the security of Belgium's electricity supply. The case comment also considers the legal and practical implications that arise as a result of employing the ‘security of electricity supply’ exemption to enable derogation from the requirements of the aforementioned Directives in circumstances where a Member State considers the security of its electricity supply to be under threat.


Author(s):  
Ying Hong ◽  
Xuesheng Wang ◽  
Yan Wang ◽  
Zhao Zhang ◽  
Yong Han

Stainless steel 304 L tubes are commonly used in the fabrication of heat exchangers for nuclear power stations. The stress corrosion cracking (SCC) of 304 L tubes in hydraulically expanded tube-to-tubesheet joints is the main reason for the failure of heat exchangers. In this study, 304 L hydraulically expanded joint specimens were prepared and the residual stresses of a tube were evaluated with both an experimental method and the finite element method (FEM). The residual stresses in the outer and inner surfaces of the tube were measured by strain gauges. The expanding and unloading processes of the tube-to-tubesheet joints were simulated by the FEM. Furthermore, an SCC test was carried out to verify the results of the experimental measurement and the FEM. There was good agreement between the FEM and the experimental results. The distribution of the residual stress of the tube in the expanded joint was revealed by the FEM. The effects of the expansion pressure, initial tube-to-hole clearance, and yield strength of the tube on the residual stress in the transition zone that lay between the expanded and unexpanded region of the tube were investigated. The results showed that the residual stress of the expanded joint reached the maximum value when the initial clearance was eliminated. The residual stress level decreased with the decrease of the initial tube-to-hole clearance and yield strength. Finally, an effective method that would reduce the residual stress without losing tightness was proposed.


Author(s):  
Thomas G. Scarbrough

In a series of Commission papers, the U.S. Nuclear Regulatory Commission (NRC) described its policy for inservice testing (IST) programs to be developed and implemented at nuclear power plants licensed under 10 CFR Part 52. This paper discusses the expectations for IST programs based on those Commission policy papers as applied in the NRC staff review of combined license (COL) applications for new reactors. For example, the design and qualification of pumps, valves, and dynamic restraints through implementation of American Society of Mechanical Engineers (ASME) Standard QME-1-2007, “Qualification of Active Mechanical Equipment Used in Nuclear Power Plants,” as accepted in NRC Regulatory Guide (RG) 1.100 (Revision 3), “Seismic Qualification of Electrical and Active Mechanical Equipment and Functional Qualification of Active Mechanical Equipment for Nuclear Power Plants,” will enable IST activities to assess the operational readiness of those components to perform their intended functions. ASME has updated the Operation and Maintenance of Nuclear Power Plants (OM Code) to improve the IST provisions for pumps, valves, and dynamic restraints that are incorporated by reference in the NRC regulations with applicable conditions. In addition, lessons learned from performance experience and testing of motor-operated valves (MOVs) will be implemented as part of the IST programs together with application of those lessons learned to other power-operated valves (POVs). Licensee programs for the Regulatory Treatment of Non-Safety Systems (RTNSS) will be implemented for components in active nonsafety-related systems that are the first line of defense in new reactors that rely on passive systems to provide reactor core and containment cooling in the event of a plant transient. This paper also discusses the overlapping testing provisions specified in ASME Standard QME-1-2007; plant-specific inspections, tests, analyses, and acceptance criteria; the applicable ASME OM Code as incorporated by reference in the NRC regulations; specific license conditions; and Initial Test Programs as described in the final safety analysis report and applicable RGs. Paper published with permission.


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