Zaporizhzhia nuclear plant hit by shells, no radiation leaks: Ukraine regulator

Europe's largest nuclear power plant, the six-unit Zaporizhzhia in Ukraine, received a direct hit by Russian artillery shells on the nuclear compartment building of unit 1, but there was no threat of radioactive release, Ukraine's nuclear regulation agency reported March 4.

The initial assessment of damage caused by the Russian artillery attack on Zaporizhzhia revealed that at least two shells hit the dry storage site for spent nuclear fuel, but no radioactive leaks were detected there either, State Nuclear Regulatory Inspectorate Ukraine said in a statement early that morning.

"The degree of damage to the structures and systems of these nuclear installations and their impact on safety requires additional assessments based on the results of thorough inspections by special services of the operating organization," the inspectorate said.

The attack caused a fire, since extinguished, that "severely damaged" a building housing the plant's training center, located in the immediate vicinity of the reactors, it said in a later statement issued at 8:20 am local time (0620 GMT).

Ukraine was forced to shut two units that were in the line of fire of Russian artillery forces, and currently only unit 4 is connected to the power grid, operating at 69% of capacity, the regulator said.

Unit 1 was already in an outage before the attack and units 2, 3, 5 and 6 are currently cooling down, it said.

"Operational personnel, who were on shift at the time of the Russian occupation of the Zaporizhzhia NPP site, were forced to continue working at their jobs for more than 24 hours," the agency said. "There are no dead or injured among the Zaporizhzhia NPP staff. Some of the staff received medical care due to stress."

A rotation of operational staff has been carried out, and it was previously planned that the new shift would work until 11 pm local time (2100 GMT), the inspectorate said.

"The work of the personnel is carried out under pressure from the armed forces of the Russian Federation that have captured Zaporizhzhia plant," the agency said, without providing further details.

Operator fatigue could pose safety risks

Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists, suggested in a UCS press briefing March 4 that operators might be continuing to operate Unit 4 as insurance against a possible loss of off-site power supplies to the plant.

Nuclear power plants and spent fuel storage pools require secure sources of electric power even when shut down, in order to operate safety equipment and provide large amounts of cooling water for continuous removal of decay heat from fuel in the reactor cores and storage pools. Three boiling water reactors at the Fukushima I plant in Japan experienced meltdowns in March 2011, despite having already been shut after being devastated by a tsunami caused by a high-magnitude earthquake.

Lyman said he did not see any strategic interest for Russia in destroying the plants or attempting to release radioactivity from them as a weapon. However, he expressed concern that reactor operators and other workers at Zaporizhzhia might be working far longer shifts than usual and possibly are being impeded by Russian forces from leaving and entering the plant.

That situation could jeopardize safety at the plant as worker attentiveness is reduced over time by fatigue and stress, he warned.