Questions and Answers for NUMO's Geological Disposal Program
A question on high-level waste disposal
Q1. What is high-level waste?
In Japan, highly radioactive liquid waste arising from the reprocessing of spent fuel is solidified in a glass matrix. This is termed high-level waste (HLW).As of December 31st 2015, the total volume of spent fuel that had been produced is equivalent to around 24,800 canisters of vitrified waste. As of March 31st 2016, the number of canisters being stored in Japan is 2,300.
In Japan, spent fuel is reprocessed to extract uranium and plutonium for re-use in the nuclear fuel cycle. The remaining highly active liquid waste has no further use. It is immobilized in a glass matrix which is surrounded by a stainless steel fabrication canister. Internationally, countries such as Sweden have opted for direct disposal of spent fuel. In such cases, the concept of geological disposal is also applied.
NUMO's disposal program
Q2. What is the disposal concept for high-level waste?
Following a period of interim storage to allow cooling, the vitrified high-level waste will be emplaced in a deep engineering repository.
High-level waste will be disposed of in a stable geological formation at a depth of more than 300 meters. The vitrified waste in fabrication canisters will be encapsulated in strong metal containers (overpacks) and, once emplaced in the repository, will be surrounded by a clay buffer material. The canisters, overpacks and clay buffer material are referred to as the engineered barrier system. The geological environment, which isolates the waste for long time periods, is termed the natural barrier. The multibarrier system used for safe waste disposal is a combination of engineered and natural barrier. Research and development on the multibarrier system will continue with a view to building confidence in this concept.
Q3. How can the choice of geological disposal be justified?
At present, international consensus is that geological disposal is the best means of ensuring the long-term safety of waste disposal, Japan's strategy is thus in line with this consensus.The Nuclear Safety Commission of Japan is presently discussing safety regulations, which will be embodied in separate legislation. Waste disposal will have to comply with these regulations.
Q4. How much will final disposal cost?
The cost of final disposal will be approximately 3.7 trillion Japanese yen.The waste producers (utilities, JAEA and JNFL) are required to make payments into a fund which will cover the cost. These payments are reflected in the price of electricity paid by the consumer.