south burnett times article, page-4

I assume Bob Stephens has been given access to Cougar's DERM submission and has either skimmed it or not understood what he has read.

At no time has there ever been mention of an explosion in the underground burn chamber ... and he carefully words his comments on this matter so as to be ambiguous imo.

Cougar have always mainained it was a casing design issue that has been overcome with a revised design.

The magnitude of vertical casing movements mentioned by Bob are entirely expected due to thermal expansion of the casing as it heats up to operating temperature.

As an engineer, I can only muse that I would expect the casing to be effectively fixed at the bottom and an inner casing would be permitted to expand upwards as operating temperatures increase. Again, I can muse that if the inner casing was in anyway constrained in vertical expansion, it could put the casing below in compression and in the extreme perhaps local buckling is possible.

None of these issues are totally ground breaking (forgive the bad pun) ... one only has to look at issues of thermal casing expansion in the NZ geothermal industry around Taupo and Rotarua.

I hope that Cougar will correct obvious (to me at least) inaccuracies in Bob's letter.

Cheers
Dex