No: III-15-004 March 4, 2015

CONTACT: Viktoria Mitlyng 630-829-9662

 Prema Chandrathil 630-829-9663

NRC Will Continue Increased Oversight of Monticello Nuclear Plant

The Nuclear Regulatory Commission staff has decided that despite another inspection finding at the 

Monticello Nuclear Generating Plant, recent performance improvements make it unnecessary to put the facility in 

the category of plants with multiple and systemic performance issues. However, the plant will be under increased 

NRC oversight.

The NRC uses color-coded inspection findings and performance indicators to assess nuclear plant 

performance. The colors go from “green” to “white,” “yellow,” and “red,” commensurate with the safety 

significance of the issue. Performance indicators are statistical measurements of plant and equipment 

performance. The NRC’s action matrix reflects overall plant performance and agency response. There are five 

columns in the matrix with Column 1 requiring a baseline level of inspections. A move to another column results 

in an increased level of NRC oversight and inspections. If the NRC loses confidence in the plant’s ability to 

perform safely, the plant will shut down and move to column 5.

Monticello has been in Column 3 of the performance matrix since 2013 due to a yellow finding related 

to weaknesses in the external flooding strategy. The results of two recent inspections demonstrated that the plant 

has taken effective actions to resolve the issues that led to the violation. The results of the inspection, which 

focused on the flooding issue, indicated a reversal in negative trends that led to the violation. The other 

inspection, which assessed the plant’s ability to identify and resolve problems, also showed improvement in the 

plant’s performance. 

On Feb. 26, the NRC issued Monticello a greater than green security finding identified in the fourth 

quarter of 2014. While the details of this issue are not publicly available, it is important to note that the plant has 

corrected the situation. By the NRC’s normal process, this finding, aggregated with the yellow finding, would 

result in Monticello’s placement in Column 4 in the fourth quarter of last year. 

NRC will deviate from its normal process and place Monticello in Column 2 of the performance action 

matrix based on the fact that the flooding issue has been resolved; there have been no recent indications of new 

significant problems; and improvements in performance. The greater than green security finding warrants a 

follow-up inspection, which will take place after the plant has had the opportunity to address the issues that 

caused the incident. In addition, the NRC will also perform an inspection focused on persistent human 

performance concerns at the plant. 

“Plants in Column 4 tend to have broad and systematic performance issues across multiple areas of plant 

operation. Our recent inspections demonstrate that Monticello’s performance does not warrant its placement in 

Column 4,” said NRC Region III Administrator Cynthia D. Pederson. “However, we will make sure the plant can 

sustain the improvements made so far and has resolved the security finding.”

Monticello, operated by Northern States Power Company – Minnesota is located in Monticello, Minn., 

30 miles northwest of Minneapolis.
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The NRC’s assessment letter and deviation memo are publicly available on the NRC website.