Reliability and mass analysis of dynamic power conversion systems with parallel of standby redundancy

A combinatorial reliability approach is used to identify potential dynamic power conversion systems for space mission applications. A reliability and mass analysis is also performed, specifically for a 100 kWe nuclear Brayton power conversion system with parallel redundancy. Although this study is done for a reactor outlet temperature of 1100K, preliminary system mass estimates are also included for reactor outlet temperatures ranging up to 1500 K

Performance of the electrical controls for the Mini-Brayton system

The design theory and performance of a breadboard of the proposed Mini-Brayton electrical control system is presented. The Mini-Brayton is a nuclear isotope powered dynamic power conversion system. Testing was performed with an electronic simulation of a turbine alternator. Data on the voltage regulation, speed control, power consumption, reliability and transient response are presented for the breadboard

Preliminary survey of 21st century civil mission applications of space nuclear power

The purpose was to collect and categorize a forecast of civilian space missions and their power requirements, and to assess the suitability of an SP-100 class space reactor power system to those missions. A wide variety of missions were selected for examination. The applicability of an SP-100 type of nuclear power system was assessed for each of the selected missions; a strawman nuclear power system configuration was drawn up for each mission. The main conclusions are as follows: (1) Space nuclear power in the 50 kW sub e plus range can enhance or enable a wide variety of ambitious civil space mission; (2) Safety issues require additional analyses for some applications; (3) Safe space nuclear reactor disposal is an issue for some applications; (4) The current baseline SP-100 conical radiator configuration is not applicable in all cases; (5) Several applications will require shielding greater than that provided by the baseline shadow-shield; and (6) Long duration, continuous operation, high reliability missions may exceed the currently designed SP-100 lifetime capabilities

Experiment for Justification the Reliability of Passive Safety System in NPP

This article gives an overview of the formation of the global nuclear industry, highlighted a critical issue of ensuring safe operation of nuclear power systems in modern projects. Considering the use of passive safety systems in the design of a nuclear power plant, and discussed the different mathematical methods for assessing the reliability of passive systems. Also it considers the possibility of finding the mean time between failures, using these methods to assess the reliability of passive safety systems

Human reliability analysis in low power and shut-down probabilistic safety assessment: Outcomes of an international initiative

Since the beginning of the nuclear power generation, human performance has been a very important factor in all phases of the plant lifecycle: design, commissioning, operation, maintenance, surveillance, modification, and decommissioning. This aspect has been confirmed by the operating experience. A workshop was organized by the IAEA and the Joint Research Centre of the European Commission, on Harmonization of low power and shutdown probabilistic safety assessment for WWER nuclear power plants. One of the major objectives of the Workshop was to provide a comparison of the approaches and results of human reliability analyses for WWER 440 and WWER 1000, and gain insights for future application of human reliability analyses in Low Power and Shutdown scenarios. This paper provides the insights and conclusions of the workshops concerning human reliability analyses and human factors

The NASA CSTI high capacity power project

The SP-100 Space Nuclear Power Program was established in 1983 by DOD, DOE, and NASA as a joint program to develop technology for military and civil applications. Starting in 1986, NASA has funded a technology program to maintain the momentum of promising aerospace technology advancement started during Phase 1 of SP-100 and to strengthen, in key areas, the chances for successful development and growth capability of space nuclear reactor power systems for a wide range of future space applications. The elements of the Civilian Space Technology Initiative (CSTI) High Capacity Power Project include Systems Analysis, Stirling Power Conversion, Thermoelectric Power Conversion, Thermal Management, Power Management, Systems Diagnostics, Environmental Interactions, and Material/Structural Development. Technology advancement in all elements is required to provide the growth capability, high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall project will develop and demonstrate the technology base required to provide a wide range of modular power systems compatible with the SP-100 reactor which facilitates operation during lunar and planetary day/night cycles as well as allowing spacecraft operation at any attitude or distance from the sun. Significant accomplishments in all of the project elements will be presented, along with revised goals and project timelines recently developed

Equipment Reliability Process in Krško NPP

To ensure long-term safe and reliable plant operation, equipment operability and availability must also be ensured by setting a group of processes to be established within the nuclear power plant. Equipment reliability process represents the integration and coordination of important equipment reliability activities into one process, which enables equipment performance and condition monitoring, preventive maintenance activities development, implementation and optimization, continuous improvement of the processes and long term planning. The initiative for introducing systematic approach for equipment reliability assuring came from US nuclear industry guided by INPO (Institute of Nuclear Power Operations) and by participation of several US nuclear utilities. As a result of the initiative, first edition of INPO document AP-913, ‘Equipment Reliability Process Description’ was issued and it became a basic document for implementation of equipment reliability process for the whole nuclear industry. The scope of equipment reliability process in Krško NPP consists of following programs: equipment criticality classification, preventive maintenance program, corrective action program, system health reports and long-term investment plan. By implementation, supervision and continuous improvement of those programs, guided by more than thirty years of operating experience, Krško NPP will continue to be on a track of safe and reliable operation until the end of prolonged life time

Measurement of residual stresses in a dissimilar metal welded pipe

Dissimilar metal welds (DMW) are used in light water reactor power plants to join ferritic and austenitic steel piping components. High residual stresses remaining in this type of welded joint can significantly increase its susceptibility to stress corrosion cracking (SCC) under water reactor chemistry conditions. This degradation mechanism has compromised the integrity of many nuclear power plants throughout the world over the past 10 years. The Open University (OU) is undertaking a programme of research aimed at improving the reliability of residual stress measurements in DMWs using neutron diffraction. AREVA, the French nuclear power plant constructor, has developed an improved narrow gap DMW weld using a nickel-based corrosion resistant filler (alloy-52) to eliminate the risk of SCC in next generation nuclear plant. Through-wall neutron measurements have been carried out on a full-size DMW mock-up (352 mm OD, 40 mm thick) using the ENGIN-X instrument at the ISIS Facility in the UK. The results have shown that the largest tensile stress components in the welded component lie in the hoop direction, and have values of around 250 MPa and 225 MPa in the austenitic and alloy-52 materials respectively. These measured stresses were in reasonable agreement with those obtained from deep-hole drilling and numerical simulations. A notable finding in the experimental work was a wide scatter in the measured unstressed lattice parameters within a range equivalent to micro-strains of ≈ 430, 400 and 600 for austenitic stainless steel, ferritic steel and alloy-52 respectively. This scatter was reduced by two orders of magnitude through making additional measurements whilst slowly rotating the stress-free reference cubes. The OU is undertaking systematic studies to identify the origins of the observed measurement scatter in order to improve the reliability of measurements

Feasibility Analysis of Solar Power for the Safety of Fast Reactors during beyond Design Basis Events

This chapter presents a new design that unites the favorable technical and ecological characteristics of the solar and nuclear power plants. The current designs of nuclear reactors promise integral configuration of the primary coolant loop, secondary coolant loop, and a number of passive safety functions and overall simplification of the reactor. The present nuclear reactor design emphasizes on the safety of the reactor core at all times, i.e., controlling the reactor, cooling the reactor core, and maintaining containment. In case of non-availability of standby emergency DGs during beyond design basis event like Fukushima incident, etc., leading to extended station blackout conditions, the passive decay heat removal system will be affected. Hence, additional DGs have been made as a mandatory requirement in nuclear power plants. In case the ADG could not be mobilized during BDBE, an additional backup power source not affected by BDBE is appreciated. Hence in addition to the diesel power sources (EDG and ADG), a new design was developed for integration of diesel power with solar power. The hybrid system was designed to improve the reliability and availability of passive heat removal system, to ensure a reliable supply without interruption, and to improve the overall system reliability (by the integration with the battery bank). This hybrid power also gives the redundant power supply to the safety critical systems. This chapter also features a detailed reliability analysis carried out for power supplies to the safety critical loads. In addition a comparison was made between PV/diesel/battery with diesel/battery. These new hybrid systems conserves diesel fuel and reduce CO2 as well as particulate emissions that are harmful to environment health. Integration of solar power to the existing battery power will increase the reliability and extended availability of the system and thereby ensures safety of the plant during crisis/calamities

Status of the advanced Stirling conversion system project for 25 kW dish Stirling applications

Heat engines were evaluated for terrestrial Solar Distributed Heat Receivers. The Stirling engine was identified as one of the most promising heat engines for terrestrial applications. Technology development is also conducted for Stirling convertors directed toward a dynamic power source for space applications. Space power requirements include high reliability with very long life, low vibration, and high system efficiency. The free-piston Stirling engine has the potential for future high power space conversion systems, either nuclear or solar powered. Although both applications appear to be quite different, their requirements complement each other