Validate and perfect constraint-assessment tools and methods through systematic investigations of irradiated and thermally aged materials representative of different plant types, thereby strengthening and expanding the materials database and methods applicability.

Develop best-practice guidance for testing low-constraint specimens and for evaluation of low-constraint condition results in the ductile-to-brittle transition region, providing a basis for future standardisation efforts, and supporting the development and integration of a high-quality database.

Identification of inconsistencies in safety margins in RPV safety assessments through harmonisation and benchmarking activities, incorporating different constraint-assessment methods, various national practices, and material variability, using both deterministic and probabilistic assessments.

Develop best practice guidance, directly compatible with current nuclear codes, for the application of constraint-assessment methods in RPV safety evaluations and incorporating practical experience and improved methods generated during the project.

• Strengthens the capability of EU Member States and Associated Countries to assess and operate RPVs to the highest safety standards.
• Supports the retention of existing nuclear generating capacity and helps avoid additional carbon emissions that could result from premature plant shutdowns and replacement by fossil-fuel-based generation.
• Provides methodologies that will reduce unnecessary conservatism while maintaining safety and thus strengthens the European knowledge base and supports future developments in nuclear safety research
• By extending the operation of a 1,000-megawatt (MW) nuclear power plant for 10 additional years saves roughly $4 billion to $4.5 billion compared to building and running a brand-new replacement plant.

•  Procedure for low-constraint fracture toughness testing in the ductile-to-brittle transition region
•  High-quality low-constraint fracture toughness database for degraded RPV steels
•  Validated and improved constraint-assessment methods for degraded RPV materials
•  Benchmark cases for constraint-informed RPV safety assessment and quantifying the effect on safety margins
•  Best practice guidance on use and implementation of constraint- assessment in nuclear
•  Harmonisation recommendations and possible exemption rules
•  Training package on low-constraint testing and constraint-informed RPV assessment

VTT/ CEA/ FRAMATOME-G/ SCK CEN/ UJV/ IPP/ UC/ AEMI/ EDF

Project coordinator:

Sebastian.Lindqvist@vtt.fi