Prediction of the effects of radiation for reactor pressure vessel and in-core materials using multi-scale modelling


Prediction of the effects of radiation for reactor pressure vessel and in-core materials using multi-scale modelling

Prediction of the effects of radiation for reactor pressure vessel and in-core materials using multi-scalemodelling


In nuclear power plants, materials undergo degradation due to severe irradiation conditions that may limit their operational lifetime. Utilities that operate these reactors need to quantify the ageing and potential degradation of certain essential structures of the power plant to ensure their safe and reliable operation. So far, the monitoring and mitigation of these degradation phenomena rely mainly on long-term irradiation programs in test reactors as well as on mechanical or corrosion testing in specialized hot cells.

Continuous progress in the physical understanding of the phenomena involved in irradiation damage and progress in computer sciences have now made possible the development of multi-scale numerical tools able to simulate the materials behaviour in a nuclear environment. Indeed, within the PERFECT project of the EURATOM framework program (FP6), a first step has been successfully reached through the development of a simulation platform that contains several advanced numerical tools aiming at the prediction of irradiation damage in both the reactor pressure vessel (RPV) and its internals using available, state-of-the-art-knowledge. These tools allow simulation of irradiation effects on the nanostructure and the constitutive behaviour of the RPV low alloy steels, as well as their fracture mechanics properties. For the more highly irradiated reactor internals, which are commonly produced using austenitic stainless steels, the first partial models were established, describing radiation effects on the nanostructure and providing a first description of the stress corrosion behaviour of these materials in a primary coolant environment.

Recently, relying on the existing PERFECT Roadmap, the FP7 Collaborative Project PERFORM 60 was launched with the overall objective of building on the success of PERFECT to develop similar tools that would allow simulation of the combined effects of irradiation and corrosion on internals, in addition to a further improvement of the existing tools which model irradiation effects in RPV bainitic steels.

From a managerial viewpoint, PERFORM 60 is based on two technical sub-projects, namely (i) RPV and (ii) Internals. In addition, a User's Group and training scheme have been initiated in order to allow representatives of constructors, utilities, research organizations, etc. from Europe, USA and Japan to participate actively in the process of appraising the limits and potentialities of the developed tools and to assess their validation against qualified experimental data. Furthermore, significant efforts are being made to share knowledge and experience with young researchers in the field of nuclear materials degradation and to disseminate the results as widely as possible both within the project, and in international conferences, peer reviewed journals and via a dedicated website, that the latter serving as an ‘open window’ for internal communications and as a close link with similar projects underway worldwide.

PERFORM 60 officially kicked off on March 1st, 2009 for a duration of 4 years. There are 20 participants. These comprise European organizations and Universities active in the nuclear field: all are engaged directly in the consortium to provide the intended software tools and to ensure that these are underpinned by physical understanding of the main mechanisms behind the observed in-service degradation phenomena.


► Multi-scale and multi-physics modelling are adopted by PERFORM 60 to predict irradiation damage in nuclear structural materials. ► PERFORM 60 allows to Consolidate the community and improve the interaction between universities/industries and safety authorities. ► Experimental validation at the relevant scale is a key for developing the multi-scale modelling methodology.

Abbreviations: AKMC, atomistic kinetic Monte Carlo; AFTM, Advanced Fracture Toughness module; ASME, American Society of Mechanical Engineers; BWR, boiling water reactor; CP, crystal plasticity; DD, dislocation dynamics; DDD, discrete dislocation dynamics; DFT, density functional theory; DRX, X-ray diffraction; EAM, embedded atom model; EBSD, electron back-scattering diffraction; EKMC, event kinetic Monte Carlo; EPRI, Electric Power Research Institute; EU, European Union; IAEA, International Atomic Energy Agency; IASCC, irradiation assisted stress corrosion cracking; IGRDM, International Group of Radiation Damage in Metals; IRSN, L’Institut de Radioprotection et de Sûreté Nucléaire; LWR, light water reactor; MD, molecular dynamics; NEA, Nuclear Energy Agency; NULIFE, Network of Excellence for Plant Life Management Studies; OKMC, object kinetic Monte Carlo; PWR, pressurized water reactor; PERFECT, European project within the 6th framework program (2003–2008), see:; PTS, pressurized thermal shock; RCC-M, Règles de Conception et de Construction des Matériels mécaniques des îlots nucléaires des REP translated as design and construction rules for mechanical components of PWR nuclear islands; RT, rate theory; RPV, reactor pressure vessel; SCC, stress corrosion cracking; SIESTA, Spanish Initiative for Electronic Simulations with Thousands of Atoms; SP, sub-project; TAP, tomographic atom probe; TEPCO, Tokyo Electric Power Company; TEM, transmission electron microscopy; UG, User Group; VASP, Vienna ab-initio simulation package; WP, work package




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