Further delay to completion of Rokkasho facilities

Japan Nuclear Fuel Limited has announced a further three-year delay in the schedule for completing the Rokkasho reprocessing plant and J-MOX mixed-oxide fuel fabrication plant. The delay is due to additional regulatory requirements.

Japan Nuclear Fuel Limited has announced a further three-year delay in the schedule for completing the Rokkasho reprocessing plant and J-MOX mixed-oxide fuel fabrication plant. The delay is due to additional regulatory requirements. 

The Rokkasho fuel cycle centre in Japan's northern Aomori prefecture (Image: JNFL)

JNFL said the reprocessing plant is now scheduled for completion in the first-half of fiscal year 2021 (ending March 2022) instead of in the first-half of FY2018. Completion of the MOX plant has been put back from the first-half of FY2019 to the first-half of FY2022.

The company said that, during the additional three years, safety measures at both the reprocessing plant and the J-MOX fuel fabrication plant would be enhanced.

At the reprocessing plant, additional equipment and systems will be installed for the recovery of radioactivity in the event of a severe accident. An evaluation will also be carried out of the impact on control devices and equipment in the event of a leak of high-pressure and high-temperature steam, and the development and installation of relevant countermeasures, if deemed necessary. A new emergency control room will also be constructed at the reprocessing plant. Additional safety-related countermeasures will also be put in place, such as internal flood protection, strengthening of the seismic resistance of pipework, improving cooling water tower resistance against tornadoes and improving measures against internal fires.

The Nuclear Regulation Authority (NRA) will also carry out a safety review and associated procedures at the reprocessing plant during this period. JNFL noted that obtaining approvals for design and construction methods will also take some time.

At the J-MOX fuel fabrication plant, work will be carried out to enhance the earthquake resistance of structures in operations rooms. Equipment to counter internal fires will also be installed. JNFL noted that the plant floor space will need to be expanded in order to accommodate both these measures. Again, the NRA will conduct a safety review of the J-MOX plant.

JNFL said it will prioritise safety during all construction activities at both the reprocessing plant and MOX fuel plant. It added, "JNFL will use this scheduling opportunity to continue improving its quality assurance program, thoroughly inspect equipment and devices, and conduct intensive training for operators and maintenance technicians." It will also continue to make "company-wide efforts to achieve safe and stable commercial operation" at both plants.

Construction of the Rokkasho reprocessing plant began in 1993 and was originally expected to be completed by 1997. However, its construction and commissioning have faced several delays. Problems in the locally-designed vitrification plant - where dried out and powdered high-level radioactive waste is mixed with molten glass for permanent storage - have contributed to these delays. JNFL designed the vitrification unit to go with the reprocessing section supplied by Areva. The Rokkasho reprocessing facility is based on the same technology as Areva's La Hague plant in France.

Construction of the J-MOX plant at Rokkasho began in late 2010. Construction of the 130 tonne per year plant had been delayed by three years from the planned 2007 start by revision of seismic criteria following on from the powerful Niigata-Chuetsu-Oki earthquake.

Revised safety standards

Following the March 2011 accident at the Fukushima Daiichi nuclear power plant, new safety standards for power plants were introduced by the NRA in July 2013. In December of that year, new standards came into force that apply to the country's fuel fabrication plants and its reprocessing facilities. Used fuel and radioactive waste storage and disposal facilities are also subject to the revised rules, as are research reactors and nuclear fuel research centres.

The requirements vary from facility to facility, but generally include reinforcement measures against natural threats such as earthquakes and tsunamis, and in some cases tornadoes, volcanoes and forest fires.

The standards require that fuel fabrication plants are able to contain radioactive material in the event of an accident, and have measures in place to prevent accidental criticality events. Reprocessing plants need to demonstrate these as well as countermeasures specifically for terrorist attacks, hydrogen explosions, fires resulting from solvent leaks and vaporisation of liquid waste.

The NRA has allowed Japan's fuel cycle facilities to continue operating, but they have until the end of 2018 to undergo inspections to ensure they meet the revised safety standards.

In November 2015, JNFL announced that completion of the Rokkasho reprocessing plant and J-MOX plant had been postponed by around two years as work continued to comply with new the safety requirements.

Researched and written
by World Nuclear News