EU Science Hub


Publication Year: 
JRC Publication N°: 
GIADA Silvia
Oct 22 2008
Oct 24 2008

This workshop is organised by the Agriculture Unit of JRC-IPSC , in collaboration with the GEO Global Agricultural Monitoring and in the framework of the support of JRC to the Food Security Information Systems in the Horn of Africa.

Following a preliminary assessment of the relative importance of the various ageing mechanisms experienced by materials used in European nuclear power plants (NPPs), the primary purpose of this synthesis report is to deliver a coherent and comprehensive review of research into irradiation embrittlement performed during Euratom Research Framework Programmes 4, 5, 6 and 7, linking the research to the related projects, reports, materials and components.


Reactor pressure vessel (RPV) irradiation embrittlement has raised increasing concern again since the middle of the 1990s. One aspect was the beginning discussion about possible long term operation beyond the plant lifetime. Another aspect was the end of the Cold War together with the opening of Eastern Europe. The RPV of WWER-440 plants located in Eastern Europe are known to be susceptible to irradiation embrittlement because of their geometry leading to a high neutron flux.

1.2.1 Surveillance programmes

The accurate analysis of data coming from surveillance programmes (which are part of codes and standards in each country [Keim2012]) is a key factor for direct understanding of “real” materials in operating plants as their lead factor (2–18) with respect to the reactor pressure vessel (RPV) beltline is generally small [

  • Temperature: < 400 °C
  • Medium: not relevant
  • pH: not relevant
  • DO: not relevant
  • Chemical Composition: P > 0.01 wt.-%
  • Fluence: > 1021 n/m2 (E > 1 MeV)
Publication Year: 
JRC Publication N°: 
KENNY Robert

1.4.1 Susceptibility of Materials to Irradiation Embrittlement

Typically, irradiation embrittlement of the reactor pressure vessel (RPV) is to be considered in the areas near the core where neutron irradiation exceeds 1017 n/cm2 (E > 1 MeV). At lower neutron irradiation levels, irradiation embrittlement can be neglected.

1.5.1 Irradiation Embrittlement Parameters

Typical parameters varied in studies on irradiation embrittlement are especially fluence, but also chemical composition and irradiation temperature, and – to a lesser extent – flux and microstructure. Chemical composition covers the influence of certain alloying elements (intentionally inside the material) as well as the influence of accompanying elements originating from the manufacturing process (“impurities”, unintentionally inside the material).

1.6.1 Surveillance

The surveillance of the reactor pressure vessel (RPV) material is not directly a countermeasure against irradiation embrittlement but may allow the use of more realistic values of material properties for the integrity assessment of the RPV than predictive formulas. The surveillance of light-water reactor (LWR) RPVs includes destructive testing of specimens made from the ferritic base and weld metals used for the RPV beltline which are irradiated during operation with a higher neutron flux than the RPV itself.