Russia expects to reprocess all of its 'damaged' used nuclear fuel - at Mayak Production Association in Ozersk - by 2030, and to open the second stage of its centralized dry storage facility - at the Mining and Chemical Combine (MCC) in Zheleznogorsk - by 2016.

"My view is that it is better to try and reprocess, rather than store, damaged fuel to avoid the problems associated with its long-term storage," Evgenvy Kudryavtsev, head of the department for regulation of the safety of nuclear fuel cycle facilities at Russian regulator Rostechnadzor, told World Nuclear News. "We expect to complete this in Russia in 10-15 years." Kudryavtsev spoke at the side of the 58th International Atomic Energy Agency General Conference being held in Vienna this week.

Russia's stated policy is to close the nuclear fuel cycle as far as possible and utilize recycled uranium, and eventually also to use plutonium in mixed-oxide (MOX) fuel. In 2011 only about 16% of used fuel was reprocessed, but the target is 100% by 2030.

This strategy has four main elements. The RT-1 used fuel reprocessing facility at Mayak will be updated and then decommissioned in about 2030. At MCC, a MOX fuel fabrication plant for fast reactors will be completed this year; a pilot demonstration centre for used nuclear fuel reprocessing will be completed by 2016; a full-scale RT-2 facility will be completed to reprocess VVER, RBMK and BN used fuel into MOX fuel or into Remix — the regenerated mixture of uranium and plutonium oxides; and used fuel pool storage will be replaced with dry storage.

The first phase of the centralized 'dry' interim storage facility (ISF) for used fuel from its RBMK-1000 reactors - some 270 metres long, 35 metres wide and 40 metres high - was commissioned in December 2011. This is used to store 8129 tonnes of RBMK fuel from the three power plants in the country using that kind of reactor: Leningrad, Kursk and Smolensk. The used fuel from these plants was stored in on-site water-filled pools that were reaching full-capacity.

Later, used VVER-1000 fuel from reactors at the Balakovo, Kalinin, Novovoronezh and Rostov plants will also be stored at the facility. Such fuel has already been sent to Zheleznogorsk for storage in water pools. Three buildings of the dry store will ultimately hold about 30,000 tonnes of used RBMK and VVER fuel.

The fuel will be stored in the facility for up to 50 years, during which time substantial reprocessing capacity should be brought online. In the long-term, a geological repository for high-level radioactive waste is planned.

Construction of the second phase of the dry storage facility "is nearly finished" and will be commissioned at the end of next year or in early 2016, Kudryavtsev said. "It is very important that most of the accumulated fuel from Russian nuclear power plants will be shipped and stored at a single long-term storage site."


Two messages

Kudryavtsev said he had relayed two key messages at the General Conference.

The first was that although dry storage of high burnup and MOX fuel "has become a mature technology and its safety has been satisfactorily demonstrated", the risk of damage to fuel rod cladding – typically, a thin protective barrier made of zirconium alloy - from a prolonged period of irradiation during storage needs the industry's attention. With MOX fuel, this stress is caused by a build-up of decay helium. The risk of damage is not only an issue for storage of such fuel, but also for its transportation.

"If breached fuel is stored directly in the pool, there may be an additional release of fuel particulate to the water and fission gas to the atmosphere above the pool. To maintain acceptable radiation levels, additional water and air purification systems may need to be installed," he said. "If the protective barrier is under stress and in bad condition, then the overall safety of the fuel management system is at risk."

The second issue is that some types of fuel currently in storage, including legacy fuels and research reactor fuels, are already damaged. Heavily damaged fuel can be stored in canisters and safely stored under constant monitoring, but the additional release of fission products can interact with the cladding and the canisters themselves.

"That is why I believe it is better to reprocess than store damaged fuel," he said. For example, damaged fuel assemblies from the Soviet-era Paks nuclear power plant in Hungary were shipped this year to Russia for reprocessing.

Russia has "a few hundred tonnes" of poor quality fuel from the very first prototype reactors at the Beloyarsk nuclear power plant and damaged RBMK fuel which do not meet long-term storage requirements. It also had damaged fuel from some of its research facilities, which was transported for reprocessing, and from its nuclear submarine fleet, part of which is still in storage, he said.

Countries with large used fuel inventories and radioactive waste inventories are showing uneven progress, he said, but the Netherlands has "very interesting information" to share with the industry. Kudryavtsev was referring to COVRA's HABOG facility - an interim storage for high-level waste (HLW) – that was commissioned in 2003. HABOG has two compartments, one for medium-level waste such as canisters containing fuel element claddings after reprocessing of their uranium contents; and one for the vitrified HLW returned after used fuel reprocessing (fission products and transuranics). It stores all the HLW from Dodewaard fuel reprocessed at Sellafield in UK, and all the waste returned from reprocessing Borssele fuel at La Hague.

Kudryavtsev stressed the important role Rostechnadzor plays in Russia's nuclear industry. "We are independent and are not under a ministry - we report directly to the government."


Source: World Nuclear News