Chennai, May 24 : Russia's integrated nuclear power major Rosatom on Wednesday said it has shipped the thrust and supporting rings for the fifth 1,000 MW atomic power unit coming up in Kudankulam in Tamil Nadu. Items are machined rings with slots, which are designed to secure the nuclear reactor in the central part and from above, protect against vertical, horizontal dynamic loads, seismic impact, Rosatom said. The weight of one item is about 20 tons; the diameter is more than five meters. For the first time, two items were shipped by motor vehicle transport at once. First, the equipment will be delivered to the port of St. Petersburg, and then by water transport to India. The reactor is an item of the first safety class, which is a vertical cylindrical vessel with an elliptical bottom. Inside the reactor, there is a core and Internals. From above, the vessel is hermetically sealed by a cover with drives of mechanisms and control and protection units installed on it, nozzles for outputting cables of in-core monitoring sensors. India's atomic power plant operator Nuclear Power Corporation of India Ltd (NPCIL) has two 1,000 MW plants (Units 1 and 2) at Kudankulam, while four more (Units 3, 4, 5 and 6) are under construction. All the six units are built with Russian technology and equipment supplied by Rosatom. Major equipment for building the third and fourth units have reached Kudankulam from Russia. A sizable number of components for the fifth and sixth units are to come from Russia. /IANS