Arkansas Nuclear One

Arkansas Nuclear One (ANO) is a two-unit pressurized water nuclear power plant located on Lake Dardanelle outside Russellville, Arkansas. Owned by Entergy Arkansas and operated by Entergy Nuclear, it is the only nuclear power facility in Arkansas.

Units
Both units were designed by Bechtel Power and both are located on the Northeast Shore of Lake Dardanelle. Both units employ a combined number of 950 personnel at ANO. The two units generate enough power to meet approximately 56% of the total energy demand of Entergy Arkansas’ 700,000 customers.

Unit One
Unit One has a generating capacity of 836 megawatts and began commercial operation on December 19, 1974. ANO Unit 1 had its license to operate issued May 21, 1974 and it was later renewed June 20, 2001. It is licensed to operate through May 20, 2034. Its nuclear reactor and turbine generator were supplied by Babcock & Wilcox and Westinghouse, respectively. Unit One utilizes Lake Dardanelle as its source of cooling.

Unit Two
Unit Two has a generating capacity of 988 megawatts and began commercial operation on March 26, 1980. ANO Unit 2 had its license to operate issued September 1, 1978 and it was later renewed June 30, 2005. It is licensed to operate through July 17, 2038. Its nuclear reactor and turbine generator were supplied by Combustion Engineering and General Electric, respectively. Unit Two utilizes a recirculating-water system from a 447-foot tall cooling tower.

Surrounding population
The Nuclear Regulatory Commission (NRC) defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of 10 mi, concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about 50 mi, concerned primarily with ingestion of food and liquid contaminated by radioactivity.

The 2010 U.S. population within 10 mi of Arkansas Nuclear One was 44,139, an increase of 17.2 percent in a decade, according to an analysis of U.S. Census data for msnbc.com. The 2010 U.S. population within 50 mi was 308,219, an increase of 13.3 percent since 2000. Cities within 50 miles include Russellville (6 miles to city center).

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 Arkansas Nuclear One was 1 in 243,902, according to an NRC study published in August 2010.

March 2013 incident
On March 31, 2013, an industrial accident at the facility killed one person and injured eight other workers, including four seriously. The accident took place "in a non-radiation area, and there was no risk to public health and safety." According to Entergy, the old stator of Unit One's generator fell during an operation to replace it. The falling component ruptured a water pipe, causing water infiltration into the plant's switchgear, which knocked out power to all of Unit One and one train of Unit Two's electrical system, which was online at the time. The electrical failure caused an automatic shutdown of Unit Two. The plant's emergency generators started and restored power to the emergency systems of both units. Unit One was in a refueling outage. Emergency diesel generators, water pumps and feed water were functioning following a loss of all off-site power on Unit One, according to the NRC event notification. The plant was placed under an "unusual event classification", which is the lowest of four emergency classification levels for abnormal events designated by the federal Nuclear Regulatory Commission, which regulates American civil nuclear installations. One plant worker died, and ten other injuries required offsite medical treatment. The company released an official statement of condolence. Entergy announced that they would immediately commence repairs to Unit Two and hope to have the unit back online within several weeks. Entergy also acknowledged that Unit One would be offline for an extended time while the company surveyed the damage and established a timeline for repairs.

The cost of the repairs was estimated at $95–120M, not counting additional costs to replace lost electricity from the reactors being down for four months. Both units were repaired, and started up on August 7, 2013, capable of returning to full power. During the recovery from the incident a specialist engineering company named Lowther-Rolton assisted with the recovery of the existing Stator and performed a "Technical Audit" (also called a "third-party review") of the engineering for lifting and installation of the new Stator to ensure safety of operations.

December 2013 incident
On December 9, 2013, Unit Two was taken offline due to a transformer fire in the site switchyard. The fire was contained without injuries or threats to safety.

Potentially defective reactor vessel head
In December 2016, it was disclosed that a certificate of conformity for Unit 2's steel reactor vessel head, supplied by Creusot Forge, had been forged by the manufacturer, violating safety standards and potentially undermining the vessel head's mechanical ability to withstand sudden breakdown in certain conditions if excess carbon is present inside the steel.