Plant experience and evolution; high temperature components and design methods

PAPERS 15-22

A. J. Neylan, General Atomic Company, San Diego With reference to Paper 16, the SG tube vibrations were noted primarily on reactor 2. Was the fix applied to reactor 2 only? Was it possible either by subsequent test or by analysis to predict or correlate the vibrational differences with the observed spatial (looseness) differences found? What is the resulting reduction in plant design life due to tube plugging?

A. H. Speller, Paper 16

The Wylfa boilers are not pod boilers but fully occupy the annular space between the pressure vessel and the core. The internal vessel diameter is about 100 ft and small differences in construction resulted in the boiler packets being much more tightly fitted in reactor 1; consequently, the gaps are smaller and thus the gas driving forces are smaller. The problem thus principally affected reactor 2 and no modifications were needed on reactor 1.