SUBSCRIBE
PROFILE

Coolant leak at Olkiluoto 3 reactor in Finland

On March 7, approximately 100 cubic metres of radioactive coolant leaked into the containment rooms of the Olkiluoto 3 reactor in Finland. The incident, caused by human error during maintenance work, did not compromise nuclear safety.

Share:

Subscribe for unlimited access to all energy sector news.

Over 150 multisector articles and analyses every week.

Your 1st year at 99 $*

then 199 $/year

SUBSCRIBE — 99 $ for the 1st year

Create a free account to read this article

*renews at 199$/year, cancel anytime before renewal.

On March 7, a leak of approximately 100 cubic metres of radioactive coolant occurred within the containment rooms of the Olkiluoto 3 (OL3) reactor in Finland. The incident took place during annual maintenance when a hatch in the reactor pool was not properly closed before filling began.

An incident under control

Operator Teollisuuden Voima Oyj (TVO) stated that the coolant flowed into a drainage system designed to collect and remove any potential leaks. The company emphasised that the event posed no risk to personnel, the environment, or nuclear safety. The contaminated water will be treated according to established procedures, and teams promptly began cleaning the affected areas.

Regulatory oversight and corrective measures

The Finnish Radiation and Nuclear Safety Authority (STUK) was informed of the incident immediately after it occurred. It monitored the cleanup operations and continues to oversee the measures implemented by TVO. An investigation has been launched to determine the cause of the incident, and a detailed report will be submitted to authorities outlining preventive actions.

Annual maintenance and operational outlook

Maintenance work at OL3 began on March 1 and is scheduled to continue until early May. This planned outage includes fuel reloading, containment leak-tightness tests, reactor pump maintenance, and inspections of the steam generators. The incident has not impacted the operational schedule.

The OL3 reactor, with a capacity of 1,600 MWe, began regular electricity production in April 2023. This is the first maintenance performed on an 18-month operating cycle. The next major intervention is scheduled for September 2026.

  • Popular on energynews.pro
Metacon confirms partial delivery and receives EUR 14.9 million
Nano Nuclear partners with Dioxitek to strengthen Argentina’s nuclear supply chain
Ohmium reduces electrolyser footprint to 29.7 m²/MW
CATL deploys TENER Stack system in Brazil to accelerate regional expansion
Canadian Utilities secures AUC approval for Yellowhead gas pipeline project
Sweden lifts uranium mining ban to revive nuclear industry
Stockholm plans to restart uranium extraction by lifting the 2018 ban, aiming to secure strategic supply chains and support domestic nuclear electricity production.
CEA considers deploying a small Calogena nuclear reactor in Cadarache
The French Atomic Energy Commission has signed a letter of intent with start-up Calogena to study the installation of a 30 MW thermal small nuclear reactor at its Cadarache site.
Guidehouse forecasts $8.1 billion revenues for modular reactors by 2034
A Guidehouse Research report anticipates strong growth in the global nuclear modular reactor market, with revenues rising from $375.8 million in 2025 to $8.1 billion in 2034.
Several South Korean groups back $50bn nuclear projects in the United States
KHNP, Doosan, POSCO and Samsung C&T join US partners to develop 5 GW of modular reactors, expand uranium enrichment and build an 11 GW energy complex in Texas.
Washington activates Defense Production Act to secure enriched uranium
The US Department of Energy is creating an industrial consortium to accelerate domestic enriched uranium production and reduce reliance on foreign imports ahead of the Russian supply ban in 2027.
One of the drones from last weekend’s Ukrainian attack struck the Kursk nuclear power plant
The kamikaze drone damaged an auxiliary transformer at the Kursk plant, halving the output of its only reactor in operation, according to Rosatom and the International Atomic Energy Agency.
EDF restarts Gravelines reactors after shutdown caused by jellyfish
The four production units at the Gravelines nuclear power plant, shut down in mid-August by a massive jellyfish incursion, are back online, restoring the site’s full capacity.
enCore Energy completes $115M convertible notes offering
enCore Energy Corp. has completed a $115 million fundraising through convertible notes maturing in 2030, strengthening its financial capacity for upcoming operations.
Vattenfall selects GE Vernova and Rolls-Royce for future nuclear reactors
Vattenfall advances its nuclear project in Sweden by selecting two modular reactor suppliers, GE Vernova and Rolls-Royce SMR, for a potential installation on the Värö Peninsula.
NANO Nuclear Advances to Final Round of US Army’s xTechSearch 9 Competition
NANO Nuclear Energy has been selected to compete in the final round of xTechSearch 9, a US Army initiative aimed at identifying high-potential dual-use technology solutions.
Aalo Atomics raises USD 100 million to launch its first nuclear power plant
Aalo Atomics completes Series B funding, bringing its total to USD 136 million, to build its first modular nuclear power plant dedicated to data centers.
Malaysia Launches Strategic Study on Civil Nuclear Potential
The Malaysian government initiates a national assessment on nuclear energy feasibility, targeting regions facing energy supply constraints and integrating international regulatory requirements.
Premier American Uranium finalizes the acquisition of Nuclear Fuels with Court approval
The merger between Premier American Uranium and Nuclear Fuels reaches a key milestone following final approval of the arrangement plan by the Supreme Court of British Columbia.
Google and Kairos Power to Build a 50 MW Nuclear Reactor in Tennessee
TVA, Google, and Kairos Power formalize an agreement to connect an advanced reactor to the grid, supporting data center energy growth and reinforcing the U.S. nuclear industry.
X-energy and the Pentagon Accelerate Nuclear Microreactor for National Security
The U.S. Department of Defense has signed an agreement with X-energy to develop a commercial nuclear microreactor intended to power sensitive military infrastructure.
NANO Nuclear Raises $209 Million and Accelerates Microreactor Deployment
With cash reserves multiplied sevenfold in nine months, NANO Nuclear intensifies development of its KRONOS MMR and positions itself in the Canadian and U.S. modular nuclear markets.
Equinix secures 20 Radiant microreactors and a nuclear deal in the Netherlands
Equinix signed a preorder for 20 Kaleidos nuclear microreactors and a letter of intent for a power purchase agreement with ULC-Energy, reinforcing its energy supply strategy for its data centers.
Oklo selected for three pilot projects by U.S. Department of Energy
The U.S. Department of Energy selects Oklo and its subsidiary Atomic Alchemy for three pilot reactor projects aiming for criticality before July 2026.
Eleven US companies selected to fast-track small nuclear reactor testing
The United States Department of Energy has selected eleven companies to build experimental nuclear reactors by July 2026, under a programme aimed at meeting rising electricity demand.
South Africa confirms environmental authorisation for Duynefontein nuclear power plant
The South African Minister of the Environment has approved Eskom’s authorisation to build a nuclear power plant in Duynefontein, ending appeals lodged by several environmental organisations.

Log in to read this article

You'll also have access to a selection of our best content.

or

Go unlimited with our annual offer: $99 for the 1styear year, then $ 199/year.

SUBSCRIBE - €99