Taiwan: Explosion completely destroys surge protection device at Guosheng Nuclear Power Plant, May 29; could have caused ‘disastrous damage’

Nuclear Event in Taiwan on May 29 2016 04:22 PM (UTC).

Taiwan Power Co (Taipower) yesterday said that it is still investigating what damaged a surge protection device at the Guosheng Nuclear Power Plant in New Taipei City’s Wanli District earlier this month, while dismissing allegations that the incident was caused by an explosion.

Three surge arresters of the generator at the plant’s No. 2 reactor – which is undergoing annual maintenance – burned down for unknown reasons on May 16, an incident that was publicized by New Power Party Executive Chairman Huang Kuo-chang on Friday. Local residents had reported a fire at the plant, and the Atomic Energy Council on Thursday told Huang the incident was only a “tripping event,” but failed to explain what caused the event.

Huang visited the facility and saw “three surge arresters and bus bars [that] were completely destroyed by an explosion and burned black,” he wrote on Facebook on Friday. “Parts that were blown off [from arresters and bus bars] shattered the casing of a nearby fan, suggesting the power of the explosion. The most shocking part was that the explosion occurred just a few steps away from a hydrogen cooling system, which, had it been ignited, would have caused disastrous damage,” he said.

The aging plant’s damaged equipment had been in use since the plant’s construction in the 1970s, while the power generation system involved in the incident had just passed a Taipower maintenance test that was approved by the council, Huang said, questioning the reliability of the test.

The party caucus plans to propose a motion at the Legislative Yuan this week to suspend reactivation of the reactor until the cause of the explosion is understood, with reactivation subject to approval by the legislature, he said.

Taipower vice president Chai Fu-feng said a task force consisting of company officials and foreign experts is still analyzing what caused the incident, adding that what happened was not an explosion, but rather a “high-temperature compression.”

“The high-temperature compression was caused by overvoltage, with heated inflated gases inside the arrester casings triggering an electric arc effect that damaged the casings. We are still trying to understand what caused the overvoltage and are examining the power generation facilities, including fans and transformers,” Chai said.

The task force has identified a number of factors that might have resulted in overvoltage, which have yet to be confirmed and cannot be revealed at the moment, he added. The reactor was not damaged at all, he said. A complete analysis is to be submitted to the council next month at the earliest, while repairs are expected to be completed in July, meaning the reactor can only be restarted then, he said.