PRAGUE -- PRAGUE (AP) -- Dana Drábová, the popular head of the Czech nuclear watchdog for more than a quarter century during a period when the country has relied heavily on nuclear power, has died. She was 64.

Drábová, a nuclear physicist and well-known expert on nuclear energy, was head of the State Office for Nuclear Safety from 1999 until her death Monday. She died after battling a serious illness, the office said.

She had posted daily reports on X about the radiation situation in Ukraine since the Russian full-scale invasion in February 2022, with the last one posted just hours before her death.

"The daily reports are taking a break," her account announced. "The radiation situation in Ukraine remains normal."

Soon after she took the helm of the state office in 1999, the country faced strong criticism from the Austrian government and protests by anti-nuclear activists at home over a new nuclear power plant in Temelín near the Austrian border. Vienna said the plant might not be safe.

It was a baptism of fire for Drábová, who kept calm, argued factually and helped contribute to easing the controversy surrounding the plant.

Drábová served two terms on the board of governors of the International Atomic Energy Agency and chaired the Western European Nuclear Regulators Association, or WENRA. She also was an advisor to the Japanese government since 2018.

"A personality who did truly exceptional work for the security of our country has passed away," Czech President Petr Pavel said. "I loved her for her courage, humanity, and sense of humor. I respected her expertise and admired her directness and charisma."

Also, outgoing Prime Minister Petr Fiala and the winner of last week's parliamentary election, Andrej Babiš, offered their condolences.

She had been awarded state decorations by two former presidents, Václav Klaus and Miloš Zeman.

Last year, she received the Japanese Order of the Rising Sun, Gold and Silver star, for her contribution to boosting relations in the field of nuclear energy.

Dana Drábová, popular head of the Czech nuclear watchdog, has died at 64