Irradiation Embrittlement Of Reactor Pressure Vessels Rpvs In Nuclear Power Plants

Reactor Pressure Vessels (RPVs) contain the fuel and therefore the reaction at the heart of nuclear power plants. They are a life-determining structural component: if they suffer serious damage, the continued operation of the plant is in jeopardy. This book critically reviews irradiation embrittlement, the main degradation mechanism affecting RPV steels, and mitigation routes for managing the RPV lifetime. Part I reviews RPV design and fabrication in different countries, with an emphasis on the materials required, their important properties, and manufacturing technologies. Part II then considers RVP embrittlement in operational nuclear power plants using different reactors. Chapters are devoted to embrittlement in light-water reactors, including WWER-type reactors and Magnox reactors. Finally, Part III presents techniques for studying embrittlement, including irradiation simulation techniques, microstructural characterisation techniques, and probabilistic fracture mechanics. Irradiation Embrittlement of Reactor Pressure Vessels (RPVs) in Nuclear Power Plants provides a thorough review of an issue that is central to the safety of nuclear power generation. The book includes contributions from an international team of experts, and will be a useful resource for nuclear plant operators and managers, relevant regulatory and safety bodies, nuclear metallurgists and other academics in this field Discusses reactor pressure vessel (RPV) design and the effect irradiation embrittlement can have, the main degradation mechanism affecting RPVs Examines embrittlement processes in RPVs in different reactor types, as well as techniques for studying RPV embrittlement

This publication sets out the findings of a co-ordinated research project to determine the influence of the mechanism of the deterioration effect in radiation embrittlement of reactor pressure vessel steels with a high nickel content in nuclear power plants, including procurement of materials, determination of mechanical properties, irradiation and testing of specimens, and microstructural characterisation.

Specific problems such as the embrittlement of the WER reactors or the integrity evaluation of the Yankee Rowe reactor pressure vessel, show the necessity of continuing in the understanding of the mechanisms responsible for the embrittlement. Besides, in order to increase the safety and performance of the nuclear power plants, it is important to optimize the surveillance programmes and develop the mitigation techniques of the damage caused by neutron radiation.

The Swedish nuclear power plants all have plant specific surveillance programs which includes samples from all relevant materials that are subjected to a fluence-level that exceeds 1*1017 n/cm2 over the estimated period of operation for the specific power plants. The Swedish pressurized water reactor (PWR)-plants are currently planning for a service period beyond 50 years of operation. As a portion of that, two of the three PWR units at the Ringhals site are conducting a major effort to verify the fitness to service of the reactor pressure vessel (RPV). In this case it is the weld in the belt-line region of the RPV, which is the apparent limiting factor. The weld metal contains high Nickel and high Manganese levels, not commonly used in other PWR-reactors. The effort includes a densified testing of the available surveillance capsule material in order to better understand the degradation phenomena and also an extended testing scope. A spin off effect of this program is that high fluence data for the base material also is made available from the testing. The chemical composition of the base metal is valid for many of the currently operating PWR-vessels. This study is an analysis of both the weld and the base material data extracted from the surveillance program. The results are evaluated against currently available data and correlation curves. In general, the results point out that the current Regulatory Guide 1.99 revision 2-correlation regarding the prediction of as-irradiated transition temperature is under-conservative for the tested material. The transition temperature shift, here evaluated as the temperature shift at 41J, is under-predicted by the correlation by as much as 70°C in some cases and increases with increasing fluences. However, prediction made by the French average irradiation embrittlement prediction formula, FIM-formula, is consistently better but still slightly under conservative.

This report considers significant ageing mechanisms and degradation locations, as well as current practices for the assessment and management of the ageing of boiling water reactor (BWR) pressure vessels (RPVs). The report emphasises safety aspects and also provides information on current inspections, and monitoring and mitigation practices for managing ageing of BWR RPVs.

In order to develop the integrity evaluation technology for aged major components of nuclear power plants, the Japan Power Engineering and Inspection Corporation (JAPEIC) has carried out the project named "Nuclear Power Plant Integrated Management Technology (PLIM)" entrusted by Japanese Ministry of Economy, Trade and Industry since 1996 Fiscal Year (FY). One of the objectives of this project is to establish the method for integrity evaluation of aged Japanese reactor pressure vessels (RPV) by developing the prediction equations of reduction of Charpy V-notch upper shelf energy (USE) due to neutron irradiation embrittlement and the correlation equations between USE and fracture toughness. In order to study the effect of certain chemical elements, such as Cu, Ni, P and Si, and initial USE on irradiation embrittlement, nine kinds of base metal, four kinds of weld metal and one kind of heat affected zone were prepared as test materials. They were irradiated at the OECD Halden test reactor, at three fluence levels (3, 6 and 10x1019n/cm2: E>1MeV) considering total fluence estimated after 48 Effective Full Power Year (EFPY) operation of Japanese PWR plants (2 and 3 loop). Post irradiation Charpy impact tests at the upper shelf region were completed to date. This paper is an interim test report about the reduction of USE in the high fluence region.

High-performance alloys that can withstand operation in hazardous nuclear environments are critical to presentday in-service reactor support and maintenance and are foundational for reactor concepts of the future. With commercial nuclear energy vendors and operators facing the retirement of staff during the coming decades, much of the scholarly knowledge of nuclear materials pursuant to appropriate, impactful, and safe usage is at risk. Led by the multi-award winning editorial team of G. Robert Odette (UCSB) and Steven J. Zinkle (UTK/ORNL) and with contributions from leaders of each alloy discipline, Structural Alloys for Nuclear Energy Applications aids the next generation of researchers and industry staff developing and maintaining steels, nickel-base alloys, zirconium alloys, and other structural alloys in nuclear energy applications. This authoritative reference is a critical acquisition for institutions and individuals seeking state-of-the-art knowledge aided by the editors’ unique personal insight from decades of frontline research, engineering and management. Focuses on in-service irradiation, thermal, mechanical, and chemical performance capabilities. Covers the use of steels and other structural alloys in current fission technology, leading edge Generation-IV fission reactors, and future fusion power reactors. Provides a critical and comprehensive review of the state-of-the-art experimental knowledge base of reactor materials, for applications ranging from engineering safety and lifetime assessments to supporting the development of advanced computational models.

Materials in a nuclear environment are exposed to extreme conditions of radiation, temperature and/or corrosion, and in many cases the combination of these makes the material behavior very different from conventional materials. This is evident for the four major technological challenges the nuclear technology domain is facing currently: (i) long-term operation of existing Generation II nuclear power plants, (ii) the design of the next generation reactors (Generation IV), (iii) the construction of the ITER fusion reactor in Cadarache (France), (iv) and the intermediate and final disposal of nuclear waste. In order to address these challenges, engineers and designers need to know the properties of a wide variety of materials under these conditions and to understand the underlying processes affecting changes in their behavior, in order to assess their performance and to determine the limits of operation. Comprehensive Nuclear Materials 2e provides broad ranging, validated summaries of all the major topics in the field of nuclear material research for fission as well as fusion reactor systems. Attention is given to the fundamental scientific aspects of nuclear materials: fuel and structural materials for fission reactors, waste materials, and materials for fusion reactors. The articles are written at a level that allows undergraduate students to understand the material, while providing active researchers with a ready reference resource of information. Most of the chapters from the first Edition have been revised and updated and a significant number of new topics are covered in completely new material. During the ten years between the two editions, the challenge for applications of nuclear materials has been significantly impacted by world events, public awareness, and technological innovation. Materials play a key role as enablers of new technologies, and we trust that this new edition of Comprehensive Nuclear Materials has captured the key recent developments. Critically reviews the major classes and functions of materials, supporting the selection, assessment, validation and engineering of materials in extreme nuclear environments Comprehensive resource for up-to-date and authoritative information which is not always available elsewhere, even in journals Provides an in-depth treatment of materials modeling and simulation, with a specific focus on nuclear issues Serves as an excellent entry point for students and researchers new to the field

Plant life management (PLiM) is a methodology focussed on the safety-first management of nuclear power plants over their entire lifetime. It incorporates and builds upon the usual periodic safety reviews and licence renewals as part of an overall framework designed to assist plant operators and regulators in assessing the operating conditions of a nuclear power plant, and establishing the technical and economic requirements for safe, long-term operation. Understanding and mitigating ageing in nuclear power plants critically reviews the fundamental ageing-degradation mechanisms of materials used in nuclear power plant structures, systems and components (SSC), along with their relevant analysis and mitigation paths, as well as reactor-type specific PLiM practices. Obsolescence and other less obvious ageing-related aspects in nuclear power plant operation are also examined in depth. Part one introduces the reader to the role of nuclear power in the global energy mix, and the importance and relevance of plant life management for the safety regulation and economics of nuclear power plants. Key ageing degradation mechanisms and their effects in nuclear power plant systems, structures and components are reviewed in part two, along with routes taken to characterise and analyse the ageing of materials and to mitigate or eliminate ageing degradation effects. Part three reviews analysis, monitoring and modelling techniques applicable to the study of nuclear power plant materials, as well as the application of advanced systems, structures and components in nuclear power plants. Finally, Part IV reviews the particular ageing degradation issues, plant designs, and application of plant life management (PLiM) practices in a range of commercial nuclear reactor types. With its distinguished international team of contributors, Understanding and mitigating ageing in nuclear power plants is a standard reference for all nuclear plant designers, operators, and nuclear safety and materials professionals and researchers. Introduces the reader to the role of nuclear power in the global energy mix Reviews the fundamental ageing-degradation mechanisms of materials used in nuclear power plant structures, systems and components (SSC) Examines topics including elimination of ageing effects, plant design, and the application of plant life management (PLiM) practices in a range of commercial nuclear reactor types

The increasing age of European nuclear power plants and envisaged extensions of reactor pressure vessel (RPV) lifetimes up to 80 years require the accurate prediction and management of RPV neutron irradiation embrittlement. LONGLIFE ("Treatment of long term irradiation embrittlement effects in RPV safety assessment") is a collaborative project of the seventh Framework Programme of EURATOM. This project has been initiated as the next step forward towards obtaining an improved understanding of irradiation effects in RPV steels under conditions representative of long term operation (LTO) of RPVs. Phenomena that might become important at high neutron fluences (such as late-blooming effects and flux effects) must be considered in detail as part of the process of upgrading safety assessments and embrittlement surveillance procedures to underwrite the safety of LTO of RPVs. The work starts with the collection and evaluation of plant-specific information and data, such as target neutron fluences for LTO and the chemical compositions of the materials. This includes a survey of available results of RPV materials data from decommissioned plants of validating surveillance data and specific irradiation effects relevant for LTO. Microstructural data are obtained from different techniques with the aim of assessing the adequacy of current dose-damage models with respect to their relevance to the mechanisms of irradiation damage associated with LTO of RPVs. Complementary mechanical tests are performed in order to address gaps in existing experimental data. Microstructural data pertaining to the evolution of irradiation damage are correlated with changes in mechanical properties, and the most important influencing factors will be identified. Surveillance guidelines for LTO of RPV base materials and welds will be developed as one of the principal outputs of the project. The scope of work and the project structure are outlined in the paper. Two LTO relevant phenomena--late blooming effect and flux effect--are discussed in more detail.

Radiation embrittlement and its mitigation by annealing of VVER-440 reactor pressure vessel steels are studied. The Russian regulatory approach for prediction of radiation embrittlement of VVER-440 steels is considered. Results of an investigation of materials cut out of operating nuclear power plants are discussed. Different models of re-irradiation embrittlement are compared. A new model for assessment of embrittlement under re-irradiation is developed.