TAIPEI - A fire broke out at a nuclear power station in southern Taiwan shortly before midnight on Sunday, forcing the shutdown of one of its two reactors.

The fire began inside an auxiliary electrical transformer at the Third Nuclear Power Plant in Pingtung County, setting off an alarm at 11:58 pm, the Taiwan Power Company (Taipower) said.

It was put out by the plant's own firefighters 17 minutes later and the plant is continuing to operate as normal, though it is estimated that it will take two weeks to get the second reactor operational again.

The incident has caused no radioactive leak and no personnel have needed to be evacuated, Taipower said in a statement on its website.

The No 2 reactor was operating at full capacity when a short-circuit of the transformer's busbar, an assembly of conductors for collecting electric currents and distributing them to outgoing feeders, led to the reactor's shutdown, Taipower said.

A loud noise was heard at midnight around the plant as the turbine released steam into the sky during the process, the company said.

The No 1 reactor was unaffected by the incident and is operating as normal, according to the company.

Preliminary investigation showed the transformer, which was one of a number of devices supplying electricity to the plant, has been damaged and will take about two weeks to repair, Taipower said.

Electricity is still being safely supplied to the plant, as two other electricity suppliers with voltages of 345KV and 161KV are still powering it, together with three reserve emergency diesel generators.

With an electricity generating capacity of 951,000 kilowatts, the No 2 reactor was the second of the plant's two to enter operation, in May 1985.

Taiwan has three nuclear power plants in operation and another one under construction, but there has been much public debate about whether the island should become a nuclear power-free society, particularly in the wake of the Fukushima nuclear crisis that followed the massive earthquake and tsunami in the Japanese prefecture in 2011.