The Monticello Nuclear Generating Plant is a
nuclear power plant
A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a electric generator, generato ...
located in
Monticello, Minnesota
Monticello ( ) is a city next to the Mississippi River in Wright County, Minnesota, United States. The population was 14,455 at the 2020 census.
Geography
According to the U.S. Census Bureau, the city has a total area of , all land. The city' ...
, along the
Mississippi River
The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...
. The site, which began operating in 1971, has a single
nuclear reactor
A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nu ...
(
boiling water reactor
A boiling water reactor (BWR) is a type of light water nuclear reactor used for the generation of electrical power. It is a design different from a Soviet graphite-moderated RBMK. It is the second most common type of electricity-generating nuc ...
) of the
General Electric
General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...
BWR-3 design generating 671 MWe. The reactor was originally licensed until 2010; a renewal license issued in 2006 allows it to continue operating until September 8, 2030.
The plant is owned by
Xcel Energy
Xcel Energy Inc. is an American utility holding company based in Minneapolis, Minnesota, serving more than 3.7 million electric customers and 2.1 million natural gas customers in Colorado, Texas, and New Mexico in 2019. It consists of four ope ...
and operated by Northern States Power, its regional subsidiary.
Surrounding population
The
Nuclear Regulatory Commission
The Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began operat ...
defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of , concerned primarily with exposure to, and inhalation of, airborne
radioactive contamination
Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is unintended or undesirab ...
, and an ingestion pathway zone of about , concerned primarily with ingestion of food and liquid contaminated by radioactivity.
According to the 2010 U.S. Census, the population was 62,976 within of Monticello, an increase of 36.5 percent in a decade; and 2,977,934 within , an increase of 8.6 percent. Cities within 50 miles include the
Twin Cities
Twin cities are a special case of two neighboring cities or urban centres that grow into a single conurbation – or narrowly separated urban areas – over time. There are no formal criteria, but twin cities are generally comparable in statu ...
of
Minneapolis
Minneapolis () is the largest city in Minnesota, United States, and the county seat of Hennepin County. The city is abundant in water, with thirteen lakes, wetlands, the Mississippi River, creeks and waterfalls. Minneapolis has its origins ...
(38 miles to city center) and
St. Paul
Paul; grc, Παῦλος, translit=Paulos; cop, ⲡⲁⲩⲗⲟⲥ; hbo, פאולוס השליח (previously called Saul of Tarsus;; ar, بولس الطرسوسي; grc, Σαῦλος Ταρσεύς, Saũlos Tarseús; tr, Tarsuslu Pavlus; ...
(45 miles to city center).
The Monticello section of the Mississippi River remains unfrozen during winter and attracts hundreds of
trumpeter swans
The trumpeter swan (''Cygnus buccinator'') is a species of swan found in North America. The heaviest living bird native to North America, it is also the largest extant species of waterfowl, with a wingspan of 185 to 250 cm (6 ft 2 in to 8 ft 2 in ...
, largely due to warm water discharged by the nuclear plant.
Incidents and updates
Roughly 1,300 gallons (4.9 cubic meters) of radioactive water which accidentally leaked from the plant into the
Mississippi River
The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...
in an incident on 5 May 1982, was determined to be "no threat" to the public.
In January 2007 a 13-ton control box fell eight to twelve inches and caused an unexpected shutdown. This control box was located in the condenser room of the turbine building and contained valves which controlled steam pressure. Emergency response teams at the station deemed that the event was likely caused by inadequate welds at the time of installation and fatigue due to vibrations over the life of the plant.
Construction of the on-site independent
spent fuel storage installation (ISFSI) pad began in June 2007. The target date for the completion of the pads was December 2007 with insertion of the first ten dry storage containers (holding
spent fuel assemblies ) into
horizontal storage modules (HSMs) in mid-2008. Initially, 12 HSMs will be placed on the storage pad. Each HSM—a thick, reinforced, pre-cast concrete structure about the size of a single car garage—has the capacity to hold 61 fuel bundles.
On September 11, 2008, a cable fault tripped the transformer which supplied power to the site. This resulted in a loss of off-site power and the plant automatically shut down.
On September 18, 2008, an employee for a rental equipment company was electrocuted by one phase of the 115-kV power line outside of the plant due to a lack of situational awareness. The individual was raising a bucket lift without watching overhead and contacted one phase of the 115-kV line. The plant was offline at the time due to the forced outage described above.
In February 2011, the site's plant officials determined that four
control rod
Control rods are used in nuclear reactors to control the rate of fission of the nuclear fuel – uranium or plutonium. Their compositions include chemical elements such as boron, cadmium, silver, hafnium, or indium, that are capable of absorbing ...
blades could be affected by a potentially substantial safety hazard. Vice President Tim O'Connor indicated that the blades would be replaced in March.
In 2006, Xcel Energy proposed a series of upgrades to the plant in order to increase its output and extend its life for an additional 20 years. In December 2013, the Nuclear Regulatory Commission approved the license amendment allowing the unit to increase output from 600 MWe to 671 MWe However, final project implementation costs significantly outstripped initial estimates by more than $400 million. In 2015, the Minnesota Public Utilities Commission denied full cost recovery and determined that, while Xcel Energy could include the additional cost in customer rates, it could not earn a return on those costs. Xcel Energy would record a greater than $100 million loss in 1Q 2015 as a result and recouped $27 million less than expected from the project.
In March 2013, the plant was shut down for a routine refueling. During this time, workers replaced several original plant components. This increased the plant's electrical output from the original 600 MWe to 671 MWe. In early August, the plant was brought back online with the new equipment. Refueling outages as such increase the population of the plant's workforce by the thousands.
In November 2022, 400,000 gallons (more than 1500 cubic meters) of water contaminated with
tritium
Tritium ( or , ) or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with half-life about 12 years. The nucleus of tritium (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus o ...
leaked from a water pipe running between two buildings at the facility. Only 25% of the released tritium was recovered as of March 16, 2023, with cleanup continuing. Another leak of hundreds of gallons of tritium-laced water, originating from a short-term fix for the original leak, was discovered on March 22. Xcel announced that the nuclear plant would be powered down on March 24, 2023, to cut out a leaking 50-year-old pipe to repair the ongoing leak. Xcel president Chris Clark said that "there is always a risk that it would spill over again and have more tritium enter the groundwater."
Seismic risk
The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Monticello was 1 in 52,632, according to an NRC study published in August 2010.
Electricity production
See also
*
List of power stations in Minnesota
This is a list of electricity-generating power stations in Minnesota, sorted by type and name. In 2020, Minnesota had a total summer capacity of 17,944 MW through all of its power plants, and a net generation of 56,510 MWh. The corresp ...
References
footnote number 6:
Nuclear Regulatory Commission, Preliminary Notification – Region III, Sept. 15, 2008, Preliminary Notification Of Event Or Unusual Occurrence – PNO-III-08-009;
External links
Nuclear Tourist: Monticello Nuclear Power Plant
{{U.S. Nuclear Plants
Energy infrastructure completed in 1971
Buildings and structures in Wright County, Minnesota
Nuclear power plants in Minnesota
Xcel Energy