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Groundwater recovery enters final phase at Xcel Energy’s Monticello plant

Updated estimates show total volume of water higher; no risk to health or the environment

MINNEAPOLIS (December 14, 2023) — A year after detecting a leak of tritiated water from its Monticello Nuclear Generating Station, Xcel Energy has recovered the majority of the tritium released and completed actions to contain the leaked water while remediation continues.

The company has removed about 7 million gallons of water from the ground and lowered groundwater tritium concentrations at the site by more than 90%. The low concentrations continue to pose no risk to public health or the environment, as previously confirmed by the Nuclear Regulatory Commission. Tritium has not been detected in the nearby Mississippi River at any point, despite increased sampling by the company and state regulators.

In addition to permanently fixing the source of the leak during a maintenance outage in March 2023, Xcel Energy has taken numerous actions to contain the tritium to the site and facilitate its removal. The company has built an underground barrier wall as an additional groundwater containment measure, has drilled dozens of new wells to monitor concentrations in different areas of the site, has increased the frequency of its measurements and is finalizing a system of underground pumps to control groundwater flow.

“As part of our charge in providing safe, reliable and clean energy to communities, we are responsible for being good stewards of those communities and the natural environment,” said Chris Clark, president of Xcel Energy–Minnesota, North Dakota and South Dakota. “We have made significant progress over the past year to retrieve the water released from our plant and keep it on-site as we do so. We will continue to work closely with state and federal regulators to ensure a thorough remediation.” 

Upon first discovering the leak, Xcel Energy made an initial estimate of the total volume of tritiated water released. The estimate was based on the duration and flow rates of the leak known at the time. The company has since completed a detailed accounting based on more comprehensive information now available, including a higher flow rate of water and signs that the leak may have started a few weeks earlier than previously estimated. This updated and more accurate modeling places the total amount of water leaked between 750,000 and 900,000 gallons, including about 14 curies of tritium. 

The revised estimate does not present any concern for health or the environment, nor does it require any new measures as the company continues groundwater recovery. In line with state remediation guidance, Xcel Energy will continue its strategy to pump and store groundwater until all monitoring wells are below the EPA standards. The company continues to coordinate with state and federal regulators as well as local officials. After remediation efforts have finished, groundwater monitoring will continue for the remainder of the plant’s operating life.

Tritium is a compound that is naturally present in the environment and is commonly created in the operation of nuclear power plants. It emits low levels of radiation, similar to everyday materials people use and the food they eat. Tritium is only harmful when consumed in very large quantities. According to the Nuclear Energy Institute, no tritium release from a nuclear power plant has ever posed a public health threat or exceeded EPA regulatory limits in drinking water.

Visit the Monticello groundwater page for more information. 

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DATE:             December 14, 2023
                         For Immediate Release

CONTACT:      Stephen Mikkelson
                          (218) 316-3887 | Stephen.Mikkelson@state.mn.us

Xcel Energy Inc. fined $14,000 related to tritiated water storage at Monticello nuclear facility

MINNEAPOLIS (December 14, 2023) — According to a Minnesota Pollution Control Agency (MPCA) enforcement investigation, Xcel Energy Inc. began storing groundwater contaminated with tritium in aboveground storage tanks before obtaining a required permit at its Monticello nuclear power plant. Tritium is a radioactive material that leaked from the company’s facility last fall and required cleanup and on-site storage.

As part of Xcel Energy’s response and cleanup of the November 2022 release, the company needed to install temporary tanks. MPCA staff informed the company in March 2023 that the installation of storage tanks exceeding one-million gallons of total capacity would require an aboveground storage tank major facility permit.

After installing and filling more than 20 temporary tanks, the company began filling its newest tank with tritiated groundwater in early April, before obtaining the required permit. That tank increased the total capacity of its temporary tanks to just over 1.4-million gallons.

In addition to paying the $14,000 civil penalty, Xcel Energy was required to immediately obtain the permit before continuing its response and cleanup. The MPCA issued the appropriate permit in May 2023, requiring the use of temporary tanks to end by Nov. 1. The company has since transferred the tritiated water to a more permanent in-ground lined pond and has emptied and dismantled the temporary tanks.

MPCA rules and regulations are designed to protect human health and the environment by limiting pollution emissions and discharges from facilities. When companies do not fully comply with regulatory requirements, the resulting pollution can be harmful to people and the environment.

When calculating penalties, the MPCA takes into account how seriously the violations affected or could have affected the environment, and whether they were first-time or repeat violations. The agency also attempts to recover the economic benefit the company gained by failing to comply with environmental laws in a timely manner.