Completion of Ohma 1 expected in 2020

Friday, 14 November 2014

Construction of additional safety features at unit 1 of the Ohma nuclear power plant, being built in Japan's Aomori prefecture, will be completed by the end of 2020, the Japan Electric Power Development Corp (J-Power) has announced.

The construction site of Ohma 1 (Image: J-Power)

Work to build the 1383 MWe Advanced Boiling Water Reactor (ABWR) was about 40% complete in March 2011 when a tsunami caused the accident at the Fukushima Daiichi plant. Construction of Ohma 1 was suspended following the accident, but was resumed in October 2012. At that time, J-Power said it would strive to establish a safe power plant by, among other things, ensuring that reinforced safety measures are implemented that take into account the lessons learned from the Fukushima accident.

J-Power has now announced that it has concluded formulation of the measures for reinforcing safety at the plant, taking into account new safety standards set by the country's nuclear regulator in July 2013. These measures include tsunami countermeasures, ensuring power supplies, ensuring heat removal functions, and severe accident responses.

The company said that the maximum assumed ground acceleration at the site as a result of an earthquake has been revised from 450 gal to 650 gal, while the maximum assumed tsunami height has been raised from 4.4 meters to 6.3 meters.

"For design basis to prevent severe accidents, J-Power will further strengthen earthquake and tsunami resistance measures, and for the newly established measures against severe accidents, J-Power will incorporate measures to prevent core damage and containment vessel failure, and install a specified severe accident response facility as a countermeasure to terrorist attacks such as an airplane crash," the company said.

All the reinforced safety measures are being implemented during the construction of Ohma 1, J-Power said. The construction works for these measures will begin in November 2015 and are scheduled to be completed in December 2020, it said. J-Power noted that its schedule is based on estimated times for inspections and licensing by the Nuclear Regulation Authority. The budget for construction of the additional safety features is some JPY 130 billion ($1.1 billion).

J-Power plans to use all mixed oxide (MOX) uranium and plutonium nuclear fuel in the reactor core of Ohma 1. It would be the first Japanese reactor built to run solely on MOX fuel incorporating recycled plutonium. It will be able to consume a quarter of all domestically-produced MOX fuel and hence make a major contribution to Japan's "pluthermal" policy of recycling plutonium recovered from used fuel. This policy increases Japan's self-sufficiency in energy fuels from 4% to 18% by making maximum use of imported uranium.

The start of construction of the Ohma plant was originally due in August 2007, with commercial operation planned for March 2012. However, the imposition of more stringent seismic regulations put back the start of construction to May 2008 and commercial operation to November 2014.

Although construction of Ohma 1 now looks set for completion in 2020, J-Power said it has not yet scheduled a date for the start of operation of the unit.

Researched and written
by World Nuclear News