Construction of a third nuclear power reactor at Pakistan's Chashma site officially started on 28 May, according to the International Atomic Energy Agency (IAEA). The Chashma Nuclear Power Plant unit 3, also known as Chasnupp 3, is a 340 MWe pressurized water reactor (PWR) being constructed by China. It is expected to start commercial operation in 2016. There are already two 300 MWe PWRs at Chashma, also supplied by China. Chasnupp 1 started operating in June 2000, while Chasnupp 2 began operating in May 2011. The construction of Chasnupp 4, another 340 MWe PWR, has already been approved and is expected to begin in 2012. The main construction contract for units 3 and 4 - a project costing some $2.37 billion - was signed in June 2010 by the Pakistan Atomic Energy Commission (PAEC) and Shanghai Nuclear Engineering Research and Design Institute (Snerdi). Pakistan also has a Canadian-supplied 125 MWe pressurized heavy water reactor (PHWR) near Karachi, known as Kanupp.