MOSCOW — Polls are open in Kazakhstan Sunday for a landmark referendum on building the country’s first nuclear power plant, confronting the country's painful legacy as a testing ground for Soviet nuclear weapons.

The proposal is backed by the government and President Kassym-Jomart Tokayev, who hopes to boost the country’s energy security.

The plant, which is slated to be built close to Lake Balkhash in southeastern Kazakhstan, would take pressure off the coal-powered power stations on which the country heavily relies.

Although the use of renewable energy is growing, supporters believe Kazakhstan’s position as one of the world’s largest uranium producers makes nuclear energy a logical choice.

However, the use of nuclear materials remains a controversial and often sensitive topic in Kazakhstan, which was used as a testing ground for the Soviet Union’s nuclear program.

The weapon tests made large swaths of land in the northeastern Semei region uninhabitable, devastating the local environment and affecting the health of nearby residents. In total, 456 tests were carried out between 1949 and 1989 at the Semipalatinsk test site. It was officially closed in August 1991.

Critics have also drawn attention to the project’s high costs: The Kazakh government estimates that the nuclear power plant could cost up to $12 billion.

There are also concerns that Russia’s state atomic agency, Rosatom, could be invited to take part in the plant’s construction at a time when an increasing number of Kazakhs wish to distance themselves from Moscow's influence. Rosatom had previously been named by the government as one of four companies whose reactors could be used for the plant, as well as companies from China, South Korea and France.

Tokayev, who has maintained a delicate balancing act between Moscow and the West following sanctions against Russia, has tried to allay such fears by suggesting that the plant could be built by a multinational team.

“The government must analyze and negotiate,” he told reporters after casting his vote Sunday. “But my personal vision is that an international consortium of companies with the most advanced technology possible should work together in Kazakhstan.”

While the referendum is binding, it isn’t clear that the vote will be free and fair.

Some Kazakhs have sought to protest but have been impeded by authorities. Several anti-nuclear protesters were arrested across Kazakhstan Sunday, while other activists said that permission to hold anti-nuclear rallies on the day of the vote had been denied by officials in six Kazakh cities.

Radio Azattyq, the local service of U.S.-funded broadcaster Radio Free Europe/Radio Liberty, shared footage that appeared to show a voting station official in the Turkestan region dropping large numbers of papers into a ballot box.

The result of the referendum is due to be announced on Monday.