Stichting Laka

Publication Laka-library:
Vessel head penetration cracking in nuclear reactors (part I&II) (1993)

Author	Greenpeace
	6-01-3-10-57.pdf
Date	March 1993
Classification	6.01.3.10/57 (NUCLEAR SAFETY - REACTORS - GENERAL)
Front

SUMMARY

Part I

In September 1991, during routine testing on a French 900 MW nuclear reactor, a 
leak was detected at the reactor vessel bead. The cause was identified as a cracked 
vessel bead penetration. These devices allow the control rods, the crucial device for 
safely shutting down the reactor, to manoeuvre into the pressure vessel. The rupture 
of one or several vessel bead penetrations could therefore lead not only to a loss of 
coolant accident but also a severe reduction of reactor control.

Part II

Reports on vessel bead penetration cracking (VHPC) findings have not been confined 
to France, but further incidences have occurred in Sweden (Rhingals), Switzerland 
(Beznau) and Belgium (Tihange).

Although plant operators and regulatory bodies from other countries have 
reportedly been following the VHPC issue, no inspection efforts were immediately 
initiated; on the contrary, the safety implications have been played down and the 
applicability to reactors outside of France neglected.