US-based energy firm Ameren Missouri will be investing around $150m for improvements at its Callaway Energy Center, located in Callaway county near Fulton, Missouri.
Upgrades will be carried out to replace the head that fits on the nuclear reactor at the facility, reports abc17news.com.
Ameren nuclear operations senior director Shannon Abel was quoted by abc17news.com as saying: "Certain systems have to be shutdown in order to do maintenance or modifications on them and our refuelling outage allows us to do those particular those type of maintenance activities."
The facility, which supplies power to almost 700,000 households annually, had been shut down for the pending renovations since mid-October.
Ameren takes the nuclear power plant offline for maintenance and refuelling after every 18 months. This time, the energy firm will be utilising the pre-scheduled break for replacing the nuclear reactor head with the new $150m equipment.
Ameren director of engineering projects Shannon Abel said, according to abc17news.com: "The assembly is very complex. There’s a crew of about 60 people (which) actually that put the thing together. Then once it’s all together it has to be tested (to make sure) everything’s functioning the way it’s supposed to function."
The old head of the nuclear reactor had been functioning for the last 30 years.
The nuclear facility is also undergoing its license renewal process, which will allow it to function till 2044. This renewal process is expected to be concluded by the end of this year, post safety inspections by the US Nuclear Regulatory Agency.