Serious deformation of pond wall has appeared under full water level in a large clarified water pond of 1 000 m3 made out from steel thin-sheel for 300 MW unit in one power plant

having risk to lose stability and collapse.For this

a three-dimmensional finite element model of said pond has been established by using the finite element software ANSYS

and the stress strength being calculated and analysed

and the stress shtrength being evaluated according to JB4732-1995 《steel made pressure vessel analysis and design》.Results show that the integral reinforcement in joint area of barrel shell and conical shell

as well as in joint area of column and conical shell

haven't been carried out

resulting in local insufficient strength of the water pond

leading to exceeding set standard of stress

making the local deformation to be enlarged.