” NAGOYA–Chubu Electric Power Co. plans to restart a nuclear reactor west of Tokyo that was swamped with “an unprecedentedly” large amount of seawater in 2011 that caused problems to hundreds of parts.
The damaging seawater flowed into the No. 5 reactor of the Hamaoka nuclear power plant in Omaezaki, Shizuoka Prefecture, two months after the Great East Japan Earthquake and tsunami destroyed coastal areas of northeastern Japan on March 11, 2011. The Nagoya-based utility believes that repairs and upgrades can make the reactor operational again.
“We will use designs to meet the new safety standards and apply (to the Nuclear Regulation Authority),” Chubu Electric Power President Satoru Katsuno said June 7. “We completed our checks and concluded that it is sufficiently possible to use the reactor if we change some parts and implement some repairs.”
The actual application to the NRA, the country’s nuclear watchdog, is expected in 2017 at the earliest.
The No. 5 reactor has an output of 1.38 gigawatts and was the newest among five reactors at the plant. It started operations in 2005.
In May 2011, then Prime Minister Naoto Kan asked Chubu Electric Power to suspend operations at the Hamaoka nuclear plant in light of the Fukushima nuclear disaster. The utility complied.
At that time, pipes in the compound were broken, and about 400 tons of seawater entered the No. 5 reactor and other areas of the plant. Such incidents are rare at nuclear plants.
Rust and other problems were later found in 700 of the 8,700 items checked, including pipes, valves and devices in the No. 5 reactor.
However, Chubu Electric Power concluded that the safety of the reactor can be maintained if the control rods, valves and other items are replaced or fixed.
An NRA inspector expects many challenges with the utility’s application.
“An unprecedentedly large amount of seawater flowed into the No. 5 reactor. Will there be no influence (from the inflow) when the reactor is restarted? How will the utility continuously check after the restart?” the inspector said.
“It will be necessary to conduct safety screening from a viewpoint different from those used so far,” the inspector said. “Therefore, it will take considerable time for the evaluation.”
Chubu Electric Power has already applied to the NRA to restart the No. 3 and No. 4 reactors at the plant. The utility is also working to decommission the No. 1 and No. 2 reactors there.
The Hamaoka plant is considered particularly dangerous because it sits on the projected epicenter area of a long-predicted earthquake that could devastate the Tokai region in and around Nagoya. ”
by Hirobumi Ohinata