WASHINGTON, Nov 14 (Reuters) - The CEO of NuScale Power Corp defended its small modular nuclear reactor business on Tuesday, saying work continues in the U.S. and two other countries after the company canceled its first plant at an American government lab, amid rising costs.

NuScale said last week it had agreed with a Utah coalition of municipal power systems to cancel the six-reactor, 462-megawatt project, which was to be built at the U.S. Idaho National Laboratory by 2030. NuScale and the Utah Associated Municipal Power System said the cancellation was due to worries about low subscription for the plant's power.

John Hopkins, NuScale's CEO, was upbeat despite the cancellation. "I know from a financial perspective we have $200 million in the bank. That's cash, no debt. So we have a healthy balance sheet," Hopkins said at an American Nuclear Society conference in Washington.

The end of the plant, which received public funding, was a blow to U.S. ambitions for a wave of new nuclear energy to help fight climate change. NuScale's design is a departure from traditional plants powered by one or more large reactors.

In 2020, the Department of Energy approved $1.35 billion over 10 years for the plant, known as the Carbon Free Power Project, subject to congressional appropriations. The department has provided NuScale and others about $600 million since 2014 to support commercialization of small reactor technologies.

Hopkins said NuScale projects in Romania and South Korea continue to develop.

He also said a plan with service provider Standard Power to develop two gigawatts of nuclear power intended for data centers in Pennsylvania and Ohio was on track. A contract for that project would be completed "if not this week, next," Hopkins said.

NuScale was the first U.S. company to secure regulatory approval for its design of a small, modular reactor. Backers say such projects can be built in remote locations and can power heavy industries with emissions that have been traditionally difficult to abate.

NuScale said in January the target price for power from the plant jumped 53% to $89 per megawatt hour, raising concerns about customers' willingness to pay.

Critics say small, modular reactors and other advanced reactor designs are too expensive to succeed.

"The termination of NuScale's contract signals the broader challenges of developing nuclear energy in the United States," said Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists. "Placing excessive reliance on untested technologies without adequate consideration of economic viability, practicality, and safety concerns is irresponsible and clearly won’t work." (Reporting by Timothy Gardner; editing by Jonathan Oatis and Leslie Adler)