(Reuters) - South Carolina power company Scana Corp and Santee Cooper, the state-owned generating company, said on Monday they would stop building both reactors under construction at the V.C. Summer nuclear power plant.

That decision adds to the long list of reactors power companies have canceled over the past 40 years.

The companies planned to spend about $9.8 billion to build the two Westinghouse AP1000 reactors at the Summer site and originally expected the units to enter service in 2016 and 2019. They started building the reactors in 2013.

But after years of delays and billions of dollars of cost overruns at the only two nuclear plants under construction in the United States - Summer and the Vogtle project in Georgia - Westinghouse, the primary construction contractor and designer of the plants, filed for bankruptcy protection in March.

Last week, Westinghouse’s parent, Toshiba Corp, agreed to pay Santee Copper and Scana almost $2.2 billion to enable the Japanese conglomerate to walk away from the two unfinished reactors.

Santee Cooper and Scana had said they did not expect the Summer reactors to enter service until sometime after Jan. 1, 2021.

Analysts estimated the total bill for both Summer units could rise to between $14 billion to as much as $23 billion, depending on whether they included financing and transmission costs.

Separately, Toshiba agreed to pay the Vogtle owners, including Southern Co’s Georgia Power unit, almost $3.7 billion to get out of Westinghouse’s earlier commitments on that project.

The Vogtle owners said they were working on an analysis to determine the cost and timeline needed to complete the project, which Georgia Power will take to the Georgia Public Service Commission to determine the best path forward for customers.

Power companies started construction of all 99 reactors now in service in the United States before the Three Mile Island accident in Pennsylvania in 1979.

At that time, utilities had permits from the U.S. Nuclear Regulatory Commission (NRC) to build around 97 reactors, most of which were already under construction. The utilities, however, completed only 53 of those units.

See below for a list of reactors that were never finished after obtaining a construction permit from the NRC, according to data from the NRC and Reuters:

Plant Utility State Size (megawatt Cancel

electric) Date

Summer 3 Scana SC 1,117 2017

Summer 4 Scana SC 1,117 2017

Washington Nuclear 1 Energy Northwest WA 1,266 1995

Washington Nuclear 3 Energy Northwest WA 1,242 1995

Grand Gulf 2 Entergy Nuclear Operations Inc MS 1,250 1990

* Shoreham Long Island Lighting Co NY 820 1989

Seabrook 2 Public Service Co of New Hampshire NH 1,198 1988

Bellefonte 1 Tennessee Valley Authority AL 1,235 1988

Bellefonte 2 Tennessee Valley Authority AL 1,235 1988

Midland 2 Consumers Power Co MI 818 1986

Midland 1 Consumers Power Co MI 492 1986

Marble Hill 1 Public Service of Indiana IN 1,130 1985

Marble Hill 2 Public Service of Indiana IN 1,130 1985

Zimmer 1 Cincinnati Gas & Electric Co OH 810 1984

River Bend 2 Gulf States Utilities Co LA 934 1984

Hartsville A1 Tennessee Valley Authority TN 1,233 1984

Hartsville A2 Tennessee Valley Authority TN 1,233 1984

Yellow Creek 1 Tennessee Valley Authority MS 1,285 1984

Yellow Creek 2 Tennessee Valley Authority MS 1,285 1984

Cherokee 1 Duke Power Co SC 1,280 1983

Shearon Harris 2 Carolina Power & Light Co NC 900 1983

Clinton 2 Illinois Power Co IL 933 1983

Cherokee 2 Duke Power Co SC 1,280 1982

Cherokee 3 Duke Power Co SC 1,280 1982

Hartsville B1 Tennessee Valley Authority TN 1,233 1982

Hartsville B2 Tennessee Valley Authority TN 1,233 1982

Phipps Bend 1 Tennessee Valley Authority TN 1,220 1982

Phipps Bend 2 Tennessee Valley Authority TN 1,220 1982

Washington Nuclear 4 Energy Northwest WA 1,218 1982

Washington Nuclear 5 Energy Northwest WA 1,242 1982

North Anna 3 Virginia Electric & Power Co VA 907 1982

Shearon Harris 3 Carolina Power & Light Co NC 900 1981

Shearon Harris 4 Carolina Power & Light Co NC 900 1981

Bailly 1 Northern Indiana Public Service Co IN 645 1981

Hope Creek 2 Public Service Electric & Gas Co DE 1,067 1981

Callaway 2 Union Electric Co MD 1,150 1981

Forked River 1 Jersey Central Power & Light Co NJ 1,070 1980

Jamesport 1 Long Island Lighting Co NY 1,150 1980

Jamesport 2 Long Island Lighting Co NY 1,150 1980

Sterling Rochester Gas & Electric Corp NY 1,150 1980

North Anna 4 Virginia Electric & Power Co VA 907 1980

Surry 3 Virginia Electric & Power Co VA 882 1977

Surry 4 Virginia Electric & Power Co VA 882 1977

** Vogtle 3 Georgia Power Co GA 1,113 1974

** Vogtle 4 Georgia Power Co GA 1,113 1974

Tyrone 2 Northern States Power Co WI 1,150 1974

* Long Island Lighting Co, or LILCO, finished building the Shoreham reactor but was not able to operate it commercially due to opposition in New York.

** The Vogtle 3 and 4 reactors that were canceled in the 1970s are different from the reactors currently under construction in Georgia.