Commercial operation at India’s Russian-supplied nuclear power plant at Kudankulam again slipped by a month and is now expected to be in May this year, according to a new update from Nuclear Power Corporation of India Ltd. (NPCIL).

NPCIL said physical progress of the VVER-1000 project stood at 99.85 % in March. Fuel was first loaded in the unit in October 2012. It reached criticality in July 2013 and was given permission to operate at 50% power in August last year by the Atomic Energy Regulatory Board (AERB). Subsequently, the regulator allowed the unit to generate power up to 75% of its rated 1000MW capacity

According to local reports NPCIL has applied to the AERB for permission to increase the power levels up to 90%, but commercial operation is now set at May, a month later than NPCIL expected in its last update in February.

The second 1,000 MW unit at the site is planned to start commercial operations in December 2014, according to an NPCIL update that also said physical progress of the project is 97.03 % complete as of March 2014. The project passed a milestone – the containment boundary pressure test – in February this year.

The reactors at Kudankulam are India’s first collaboration with Russia’s nuclear industry and also its first deployment of pressurised water reactor (PWR) technology, dubbed VVER in Russia. The longstanding collaboration has made slow progress, hampered by political and financial issues. When the two-reactor project was first agreed the original commercial operation date for unit one was expected to be December 2007 and the second unit was planned to reach commercial operation in December 2008.