Decommissioning of Chernobyl units approaches

Wednesday, 19 February 2014

Work could soon start on decommissioning units 1 to 3 of the Chernobyl nuclear power plant in Ukraine after a project to put the units into care and maintenance was approved by a state review authority.

The Chernobyl plant site (Image: ChNPP)

The review by State Enterprise Ukrderzhbudekspertiza confirmed that the project to 'ultimately close and mothball' the units is in accordance with all necessary regulatory and legal requirements.

Work to bring the three units into a 'conserved' state will be carried out in six stages between now and 2028. The first stage is to refurbish the water supply system for the plant's fire protection system. The second stage will involve the dismantling of the pressure tubes and control and protection channels of units 1 to 3. The reactors of units 1 and 2 will then be put into a state of care and maintenance in which they will lie undisturbed, allowing the remaining radioactivity to decay naturally. In the fourth stage, the roofs of the reactor halls of units 1 and 2 will be refurbished while the fuel handling machines of those units will be dismantled. The plant's third unit will then be put into care and maintenance, while in the final stage the unit's reactor hall roof will be refurbished and its fuel handling machinery dismantled.

The Chernobyl site operator said that the ultimate aim of the project is to bring units 1, 2 and 3 "to a condition that ensures safe, controlled storage of radioactive substances and sources of ionizing radiation within them." It said that the project will cost more than UAH385 million ($43 million).

The operator said that the review authority's approval of the project will allow it to obtain a permit to perform the work and start decommissioning of the units.

For the period between 2028 and 2046, the most contaminated equipment will be removed from the units, while the reactors themselves will be dismantled between 2046 and 2064.

On 26 April 1986, the Chernobyl plant suffered the worst nuclear accident in history when a power runaway event wrecked reactor 4. The three remaining reactor units, however, were vital to Ukraine's electricity needs and continued to operate for some years. Unit 2 shut down in 1991, unit 1 in 1996 and unit 3 in 2000.

The decommissioning of units 1-3 is being carried out separately from that of the destroyed unit 4, which is expected to take many years longer to complete.

Researched and written
by World Nuclear News