A federal inspection of Missouri's only nuclear power plant found three violations, none of which were critical.
The nuclear plant, located in Callaway County, had two violations related to mitigating systems and failed to maintain standard siren height.
The U.S. Nuclear Regulatory Commission inspected Ameren Missouri's nuclear power plant from July 1 through Sept. 30. Subsequent findings and the inspection report were issued Nov. 8.
The Callaway Energy Center is Missouri's only nuclear power plant and it produced almost 11 percent of the state's electricity last year, according to the U.S. Energy Information Administration.
Coal-fired power plants, by comparison, made up 70 percent of the state's electricity production last year.
NRC conducts routine inspections of the country's nuclear power facilities each quarter using the Reactor Oversight Process, a review program to ensure plants are operating safely.
The inspection looks at seven cornerstones for safe operation, all of which contribute to upholding reactor safety, radiation safety and safeguards.
Two of the Callaway nuclear plant's violations were concentrated to one cornerstone: mitigating systems.
Federal inspectors reviewed select procedures and records, observed employee activities and interviewed personnel to assess the facility's overall performance and compliance with NRC rules and regulations, procedures and standards, according to the inspection report.
The first violation was a failure to establish proper specifications for motorized valves, which resulted in excessive force being used to close them. The extra 25 percent of applied force created a long-term failure in the valve and prevented the facility from using an additional cooling mechanism.
The second violation was a failure to monitor the service water system performance. The inspection found the nuclear plant didn't conduct a required maintenance evaluation or establish goals for the system. As a result, the system had at least two preventable function failures.
Both violations were given green performance indicators, meaning the findings were of "very low safety or security significance."
Additionally, NRC found the Callaway nuclear plant had most of its sirens mounted on poles approximately 10 feet off from the regulatory specifications of 50 feet above the ground.
Between December 2020 and January 2021, the Callaway Energy Center replaced 23 of its 29 sirens and placed them on poles 40 feet above the ground. The facility didn't submit the change to FEMA for approval, which is a requirement when deviating from standard design elements.
According to the inspection report, the Callaway Energy Center is evaluating the differences in design and will coordinate with FEMA to work on a resolution.
NRC will make a determination on whether the siren heights constitute a performance deficiency after FEMA makes a determination on whether they are acceptable at 40 feet.
The Callaway nuclear plant passed all other inspections related to reactor safety, radiation safety and safeguards, which included reviews of weather protections, equipment alignment, operator performance and fire protections, among other measures.
The Callaway Energy Center has maintained a strong inspection record since it began operating in 1984 as NRC inspection reports routinely find that plant operations preserve public health and safety.
In 2015, NRC granted the Callaway Energy Center a license extension for 20 years, which allows the nuclear plant to operate through 2044.