SYMPOSIA PAPER Published: 01 June 2023

Long-Term Aging of NPP Ferritic Steels and Components


A review of long-term thermal aging data from reactor pressure vessel steels shows that the main aging mechanism is embrittlement from phosphorus segregation to grain boundaries. Some softening can be seen in lightly tempered steels or hardening in high-copper steels. An investigation of data from the UK's Sizewell B reactor indicates that hardening may also be distinguishable around flaws if plastic zones are introduced just prior to service in a stress test.

Author Information

Styman, Paul
National Nuclear Laboratory, GB
Chivers, Katharine
EDF Energy, Gloucester, GB
Long, Elliot
Electric Power Research Institute, Palo Alto, CA, US
Ortner, Susan
National Nuclear Laboratory, GB
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Pages: 105–120
DOI: 10.1520/STP164720220040
ISBN-EB: 978-0-8031-7742-0
ISBN-13: 978-0-8031-7741-3