OREANDA-NEWS. February 16, 2010. The strength and tightness testing of the leak-tight enclosure system (LES) was successfully carried out at Bushehr NPP (the Islamic Republic of Iran) being built by JSC Atomstroyexport.

The leak-tight enclosure system is a confining system; its main purpose is to prevent releases of radioactive substances into the external environment in case of failures in the primary circuit and to protect the primary equipment against external impacts.

The leak-tight enclosure system has been restored by the Russian specialists after the work had been terminated by the German Concern Kraftwerk Union A.G. Its main feature that makes it different from LES at the Russian plants is the steel protective shell in the form of a sphere of 56 meters in diameter, which contains the major primary equipment, i.e. the reactor, steam generators, main circulation pumps, pressurizers.

The works to erect and test such LES structure are carried out by the Russian specialists for the first time, because a reinforced concrete structure lined with steel sheets is used at the Russian NPPs.

At present, Bushehr NPP is preparing for the hot runs of the reactor installation.