Indonesian authorities have launched an investigation into radioactive contamination at a housing estate near a nuclear research reactor outside Jakarta.

Officials first discovered elevated radiation levels at the site in late January during a routine check, and suspect the caesium-137 was dumped there from the nearby reactor.

Authorities say a cleanup of soil and vegetation from the site has brought radiation levels down; they are also carrying out medical exams of residents living in the area.

Environmental activists have renewed their calls for the Indonesian government to refrain from developing nuclear power in the country, given the inability of regulators to police even a research facility.

JAKARTA — Authorities in Indonesia have launched an investigation following the discovery of radioactive contamination in an empty lot in a housing complex near a nuclear research facility.

The Nuclear Energy Regulatory Agency, or Bapeten, recorded elevated levels of the radioactive isotope caesium-137 from a routine test at the estate in South Tangerang, a satellite city of Jakarta. The agency has since 2013 conducted regular checks in the estate, which is part of a complex that includes a research reactor run by the National Nuclear Energy Agency, or Batan.

Radiation levels in the empty lot showed 680 millisieverts (mSv) per hour when experts checked at the end of January. That’s about the same as the maximum level of radiation that workers responding to the Fukushima nuclear plant meltdown in Japan in 2011 were exposed to. The normal level determined by Indonesian regulators is 0.03 mSv per hour.

“We found it in the form of shards, so we need to examine it in our laboratory to identify the source of the radioactivity,” said Heru Umbara, a Batan spokesman.

Authorities have collected 115 barrels’ worth of soil and vegetation from the affected lot. Radiation levels there have since dropped to “low levels,” they say, but cleanup efforts were still underway as of Feb. 16.

Direct exposure to large amounts of caesium-137 can cause burns, nausea and even death in some cases. Prolonged exposure also increases the risk of cancer. Bapeten said it had examined nine residents living in the vicinity of the contaminated site. A resident who has lived across from the contaminated lot for more than 10 years, David, said he hadn’t experienced any strange symptoms. He told Mongabay that motorcycle taxi drivers often waited at the empty lot for passengers

Bapeten said it suspected that radioactive material had been deliberately dumped in the lot, likely from the research reactor some 3 kilometers (1.9 miles) away. Indonesia’s nuclear program is limited to research at three reactors.

“We are investigating this further,” said Indra Gunawan, Bapeten’s general counsel.

The discovery has renewed calls by environmental activists for the government to steer clear of developing nuclear power in the country. The government and parliament are drafting a bill on new and renewable energy, which includes nuclear energy.

“This case is a bad precedent for the government and Batan, who have failed to protect public health from the dangers of radioactive waste,” Hindun Mulaika, an energy campaigner at Greenpeace Indonesia, said in a statement.

“The Indonesian government must start to focus more on pushing investment into renewable energy resources that are safer, cheaper, cleaner rather than coal power plants or even nuclear power plants,” she said.

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