The completion of additional required safety measures at unit 2 of Japan’s Onagawa nuclear power plant in Miyagi Prefecture will not be completed until 2022/3, two years later than previously scheduled.
Tohoku Electric Power Company, which operates the 825MWe boiling water reactor, reported the delay at its regular press briefing on 30 April.
The Nuclear Regulation Authority (NRA) approved the planned safety upgrades to Onagawa 2 in February, clearing the way for it to resume operation.
“Regarding the safety measures for Onagawa unit 2, we were aiming to complete the construction in 2020, but now we are aiming to complete the construction in 2022,” the company said.
Japan's NRA and relevant local governments, including Miyagi Prefecture, Onagawa Town, and Ishinomaki City, will be informed of the delay.
Tohoku had expected to spend about JPY340 billion ($3.2 billion) on the countermeasures, which include seismic reinforcement of Onagawa 2 and construction of a 29-metre high and 800m long sea wall to protect the plant from tsunamis.
The company had initially planned to complete this work by April 2017, but the schedule has been pushed back several times.
Tokohu said it had reviewed its upgrade plan following discussions with NRA.
The main works that need to be changed include “improvement measures for groundwater level lowering equipment" and the emergency seawater pump room, as well as “installation work for tornado protection".
This construction work needs to be carried out "in a small area" around the sewater pump room and could not take place simultaneously, Tohoku said.
To avoid congestion and in the interests of safety, the construction period will be extended until FY 2022 (ending March 2023).
“In the future, we will continue to make steady efforts not only to comply with the new regulatory standards, but also to further improve the safety level of the nuclear power plant," Tohoku said.
The Onagawa plant was the closest nuclear station to the epicentre of the March 2011 earthquake and tsunami, but sustained less damage than expected. This enabled operates to bring its three boiling water reactors to cold shutdown. Onagawa 1 briefly suffered a fire in the non-nuclear turbine building.
Tohoku has decided to decommission Onagawa 1, but hopes to restart unit 3 at the plant.
Photo: Onagawa Nuclear Power Plan taken by Nekosuki600(talk / Contributions) in November 16th 2003 and uploaded by Nekosuki600(talk / Contributions) to Japanese Wikipedia in September 25th 2005