JRQ and JPA irradiated and annealed reactor pressure vessel steels studied by positron annihilation

ABSTRACT

The paper is focused on a comprehensive study of JRQ and JPA reactor pressure vessel steels from the positron annihilation lifetime spectroscopy (PALS) point of view. Based on our more than 20 years’ experience with characterization of irradiated reactor steels, we confirmed that defects after irradiation start to grow and/or merge into bigger clusters. Experimental results shown that JPA steel is more sensitive to the creation of irradiation-induced defects than JRQ steel. It is most probably due to high copper content (0.29 wt.% in JPA) and copper precipitation has a major impact on neutron-induced defect creation at the beginning of the irradiation. Based on current PALS results, no large vacancy clusters were formed during irradiation, which could cause dangerous embrittlement concerning operation safety of nuclear power plant. The combined PALS, small angle neutron scattering and atomic probe tomography studies support the model for JRQ and JPA steels describing the structure of irradiation-induced clusters as agglomerations of vacancy clusters (consisting of 2–6 vacancies each) and are separated from each other by a distribution of atoms.

KEYWORDS:

• Nuclear materials
• positron annihilation spectroscopy
• RPV steel
• irradiation
• ion beam implantation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This article was created with the support of the Ministry of Education, Science, Research and Sport of the Slovak Republic within the Research and Development Operational Programme for the project ‘University Science Park of STU Bratislava’, ITMS 26240220084, co-funded by the European Regional Development Fund and Slovak Academic Information Agency. Authors acknowledge also the support by VEGA 7/00204/13.