1 Mars 2016
March 1, 2016
THE ASAHI SHIMBUN
Just three days after restarting, a reactor at the Takahama nuclear power plant came to a sudden halt when an automatic stop signal activated Feb. 29, the second recent incident that has local officials concerned.
The stoppage occurred in the No. 4 reactor at the plant in Takahama, Fukui Prefecture, in which radioactive water had been found leaking from a pipe on Feb. 20.
Radioactive material was not emitted in the latest mishap, according to Kansai Electric Power Co.
The problem occurred in the vicinity of the transformer, but the exact cause has yet to be determined, the operator announced in a news conference at its head office in Osaka on March 1.
The transformer boosts the voltage of the electricity produced by the generator from 23,000 volts to 500,000 volts before transmitting it through power lines.
“We find the continuous mishaps at the No. 4 reactor, the water leak on Feb. 20 and the latest halt of the reactor, highly regrettable,” Fukui Prefecture Deputy Governor Tatsuji Sugimoto told Kansai Electric executive Vice President Hideki Toyomatsu in a videoconference at 4 p.m. on Feb. 29.
Kansai Electric has halted all work regarding the resumption of the reactor until it can pinpoint the source of the problem.
The reactor ceased operations automatically shortly after it had started generating and transmitting power. The shutdown occurred as the power generation and transmission procedures were being monitored by media representatives at a nearby Kansai Electric facility.
Although the utility plans on starting the commercial operation of the reactor in late March, the latest setback could cause a significant delay as the investigation into the problem “will take days,” according to a company official.
Despite the Feb. 20 leakage incident, the No. 4 reactor went back online Feb. 26 after passing new safety checks introduced to nuclear power plants in the aftermath of the Fukushima nuclear disaster, which unfolded five years ago.
An alarm went off in the control room at 2:01 p.m. on Feb. 29 just as the operator started transmitting power at 5 percent output, bringing the generator to a halt. Electricity had been generated by rotating the turbine with the steam from the heat of the nuclear reaction taking place inside the reactor. A second later, the No. 4 reactor automatically stopped and all its control rods were inserted to terminate the reaction of the nuclear fuel.
The operator shortly afterward notified the Nuclear Regulation Authority and the Fukui prefectural government of the incident.
Kansai Electric divides its incidents into five categories between Level 0 for mishaps that do not have to be publicized and Level 4 for those that require swift announcements. With the reactor forced to halt, the latest incident was designated a Level 4.
Local government officials are becoming uneasy over the series of problems that have continued to plague the reactor's restart.
“With these errors happening so often, we're thinking, ‘Enough is enough,’” said Ryozo Tatami, the mayor of neighboring Maizuru, Kyoto Prefecture.
Maizuru is just west of Takahama, and some parts of the city are less than 5 kilometers from the nuclear plant.
Keiji Yamada, the governor of Kyoto Prefecture, which has seven municipalities that are within 30 kilometers of the plant, said, “We urge them to find the cause of the error and report the preventative measures properly.”
(Hiroki Ito contributed to this article.)
FUKUI – Commercial operation of the troubled reactor 4 at the Takahama facility in Fukui Prefecture will likely be pushed back to April after the Nuclear Regulation Authority said it will be difficult to proceed until preventive steps are approved.
Kansai Electric Power Co. had initially planned to start commercial operation of the reactor in late March.
The change in schedule became necessary after the reactor shut down automatically Monday, only three days after coming back online under safety regulations strengthened following the 2011 Fukushima meltdowns.
Kansai Electric said there was no leak of radioactive substances in the incident. But the shutdown followed a leak of radioactive coolant water at the reactor just days before its restart.
The utility said Tuesday a strong electrical current beyond a preset level may have been detected by a monitoring device around a transformer of the reactor, causing an alarm to go off upon the start of power generation and power transmission.
Also Tuesday, the utility began the process of bringing the unit to a state of cold shutdown by lowering the temperature of coolant water.
The NRA will eventually have to examine Kansai Electric’s analysis of the cause of the emergency halt and measures to prevent a similar incident.
Even if it gets the go-ahead for another restart, the No. 4 reactor will need to go through a final inspection by the NRA again before reactivation and subsequent commercial operation.
The latest incident was the second halt of the reactor in 10 days, following the radioactive coolant water leak on Feb. 20 in a building attached to the reactor. Kansai Electric had rebooted it, deeming it had taken sufficient steps to prevent a similar leak.
The rash of incidents come as the government aims to bring more reactors back online after the disaster at the Fukushima No. 1 nuclear power plant led to a nationwide shutdown of nuclear plants, as it is seeking to generate at least 20 percent of Japan’s electricity through nuclear power by 2030.
“It’s very regrettable,” industry minister Motoo Hayashi said of the latest incident. “I hope Kansai Electric will do its utmost to find the cause of the incident and work extra carefully,” putting safety ahead of the need to restart the reactor quickly.