Assessments of the resistance to fast fracture of the beltline region
of a PWR vessel subjected to a pressurized thermal shock (PTS) transie
nt have been carried out using the procedures of French (RCC-M) and Ge
rman (KTA) design codes, and comparisons made with results obtained us
ing the R6 procedure as applied for Sizewell B. The example chosen for
these comparisons is of a generic nature, and is taken as the PTS ide
ntified by the Hirsch addendum to the Second Marshall report (1987) as
the most servere transient with regard to vessel integrity All assess
ment methods show the beltline region of the vessel to be safe from th
e risk of fast fracture, but by varying factors of safety. These facto
rs are discussed in terms of margins between limiting and reference de
fect sizes, fracture toughness and stress intensity factor, and materi
al temperature and temperature at the onset of upper-shelf materials b
ehaviour. Based on these studies, consideration is given to issues inv
olved in the harmonization of those sections of the design codes which
are concerned with methods for the demonstration of the avoidance of
the risk of failure by fast fracture.