On 21st April 2021, Nam Theun 2 started major maintenance operations on one of its four Francis turbines for the first time after 10 years of operations. This major overhaul, conducted with the support from experts from Thailand and France, consisted of the lifting and dismantling of the generating unit for inspection and basic maintenance. General maintenance programs were also scheduled at the switchyard and regulating dam downstream of the powerhouse. This major overhaul was the fruit of over 6 months of preparation with the local authorities and communities in order to ensure the safety of populations living in the project area.
Also scheduled during this major overhaul, maintenance operations were performed on the water channel downstream of the powerhouse (the downstream channel), in order to inspect and reinforce parts of the structure for better performance.
Maintenance works on the downstream channel were completed on 31st May 2021, with the successful re-watering of the man-made channel at 5AM.
The re-commissioning of the Francis turbine FU03 was successfully completed on 4th July 2021 after positive runout and load rejection tests results. This re-commissioning was done after a 4-week delay was induced due to subpar results from the previous tests performed on the unit which required additional adjustments.
Major overhaul operations on the generating units were conducted for the first time in 2020 with the Francis unit FU04. After 10 years of operation since 2010, Nam Theun 2 will conduct major overhauls once a year for each generating turbines. In 2022, Francis unit no.2 will undergoing its major maintenance schedule.