Test operation begins for world’s first deep geological nuclear waste repository in Eurajoki

The test operation of the spent nuclear fuel repository has commenced in Eurajoki, Olkiluoto. Named Onkalo, this facility is the world’s first deep geological repository for high-level nuclear waste. In the upcoming months, the repository will be tested without any actual spent fuel.

During this phase, the systems and equipment of the repository will be operated together for the first time in accordance with planned processes. According to a statement from Posiva, the test phase aims to ensure safe disposal before the actual operations begin. Spent fuel cools for approximately 40 years prior to disposal.

At Posiva’s facility, the fuel will be encapsulated in cast iron canisters, which are protected by a corrosion-resistant copper shell. These canisters will be placed in drilled holes nearly half a kilometer deep, surrounded by bentonite clay. During the test operation without nuclear waste, four canisters will be placed in eight-meter-deep holes within a roughly 70-meter-long repository tunnel, which will then be filled with bentonite clay and sealed with a concrete plug. The test will also simulate the retrieval of a damaged canister to the surface.

“There are many unique devices and systems, the result of decades of research, that are being used together for the first time. Therefore, this test is also referred to as a collaborative trial. It is a significant test for our organization,” stated Posiva’s Production Director, Karri Osara.

According to Posiva’s CEO, Ilkka Poikolainen, this test operation marks a historic milestone for both Posiva and the world. “Posiva is now taking a significant step closer to commencing actual disposal operations.” While the exact start date for disposal has not yet been disclosed, Poikolainen mentioned earlier this year that the plant is expected to be operational by the middle of this decade.