Development of advanced CRDM without canopy seal welds
Kiyoshi Takanabe a,*, Takashi Miyake a, Yasumi Nagura b
a Mitsubishi Heay Industries Ltd., 1- 1- 1 Wadasaki-cho, Hyougo-ku, Kobe 652- 8585, Japan
b Mitsubishi Heay Industries Ltd., 2- 1- 1 Shinhama, Arai-cho, Takasago 676- 8686, Japan
Received 4 April 2001; received in revised form 20 July 2001; accepted 20 November 2001
Abstract
Leakage of primary coolant from the canopy seal welds of control rod drive mechanism (CRDM) for PWR has
been reported not only in Japan but also all over the world since the 1970s. The canopy seal weld is a circular weld
designed to retain the pressure of reactor coolant while the strength of joints is maintained by thread. Since the
coolant inside the canopy seal welds makes it easier for dissolved oxygen density to increase when a plant starts up,
stress corrosion cracking (SCC) becomes a potential issue. Consequently, an advanced CRDM housing that
eliminates all canopy seal welds has been studied, verified, and now applied to Vessel Head Replacement (VHR)
plants in Japan.
发表于 2010-9-13 09:35:12