A serviceman with a Russian flag on his uniform stands guard near the Zaporizhzhia nuclear power plant outside the Russian-controlled city of Enerhodar, Ukraine, on August 4. (Alexander Ermochenko/Reuters)
CNN  — 

“The day has come,” Rafael Grossi, the head of the International Atomic Energy Agency (IAEA) declared Monday, marking the beginning of his journey to the largest nuclear plant in Europe that sits on the fire line between the Russian occupiers and Ukrainian forces.

On Thursday, a group of 14 inspectors led by Grossi arrived at the Zaporizhzhia nuclear power plant (NPP) in southern Ukraine, despite concerns about constant shelling in the area.

Since early March, when Russia captured the plant, international and local experts have voiced grave warnings, not only for the safety of the plant’s workers, but also for fear of a nuclear disaster that could affect thousands of people in the surrounding area.

Here’s a closer look at the perilous situation at the plant:

The significance of the plant

Ukraine relies heavily on nuclear power – about half of its electricity comes from 15 nuclear reactors at four plants across the country, according to the World Nuclear Association.

Zaporizhzhia NPP, with six reactors, is the largest nuclear power station in Europe. It was mostly built in the Soviet era and became Ukrainian property after its declaration of independence from the Soviet Union in 1991.

Until recently, only two reactors were connected to Ukraine’s national grid and providing power, though the units have been taken offline at various points – and for various reasons – since the invasion.

Where is it and who controls it?

Zaporizhzhia NPP is located on the eastern bank of the Dnipro river in Ukraine. The area, and the nuclear complex, has been under Russian control since the beginning of the war, but the plant is still mostly operated by Ukrainian workers.

At the start of the invasion, Ukrainian forces stopped Russian forces from capturing a second nuclear facility – the South Ukraine Nuclear Power Plant – and forced them to retreat to Dnipro, according to Petro Kotin, president of Energoatom, which runs nuclear power plants in Ukraine. The frontline hasn’t moved much in months.

Each of Zaporizhzhia’s reactors would cost $7 billion to replace, making the plant a target for Russians to capture undamaged, with hopes of serving its own electricity market, according to analysis by defense and security intelligence firm Janes. Should Russia keep it, Ukraine would lose 20% of its domestic electricity generating capacity.

What does its position on the frontline mean?

Shelling in the surrounding towns as well as near the power plant is common, according to local reports.

Ukraine has accused Russian forces of storing weaponry and launching attacks from the plant, knowing that Ukraine can’t return fire without risking hitting the nuclear facility. Russia in turn claims Ukrainian forces are targeting the site.

The international community has been on high alert about nuclear safety, yet experts believe a Chernobyl-style disaster is unlikely. The plant is equipped with modern security systems, meaning even if there was neglect to its upkeep, or major military action caused serious damage, the result would be most comparable to the nuclear disaster in Fukushima – which was contained locally, according to Janes and Energoatom.

Yet risks remain, one of which is potential damage to nuclear waste stored openly on site – in ponds of water and in casks, according to Kotin from Energoatom.

Kotin has also warned that Russian attempts to switch the plant from the Ukrainian to the Russian power grid would require disconnecting all the reactors from power for a certain time, relying on emergency power generation never failing – a “very dangerous” prospect, he told CNN in an August 22 interview.

Which parts of the plant have been affected by the conflict?

The plant’s main exclusion security zone, where the reactors and nuclear fuel are located, is surrounded by Dnipro waters to the northwest and Enerhodar town to the east.

The below satellite image highlights the plant’s facilities, which are vital to the accompanying timeline of events since the war began. They show just how narrowly Zaporizhzhia NPP has avoided a nuclear disaster.

Key developments at the plant since the start of the war

March 4, 2022

Russian troops take control of the Zaporizhzhia nuclear power plant (NPP), with operators working at “gunpoint,” according to Ukrainian nuclear officials. Russian shelling damages buildings around one nuclear reactor and Ukrainian authorities say a fire breaks out at a training center outside the main site. The UN’s nuclear watchdog, the International Atomic Energy Agency (IAEA), condemns the move.

Smoke rises from administrative buildings at Zaporizhzhia NPP on March 5, 2022. (IAEA/Energoatom via Telegram)

March 6

The UN and Ukrainian nuclear regulators lose lines of reliable communication with the plant’s workers as Russia switches off some mobile networks and the internet at the plant.

March onwards

Two out of six reactors in the plant are active. Meanwhile, the frontline – along the River Dnipro that the plant stands on – has moved little since early March. Kyiv has repeatedly accused Russian forces of storing heavy weaponry inside the complex and using it as cover to launch attacks.

Russian military patrols the territory of the Zaporizhzhia nuclear power plant on May 1. (Andrey Borodulin/AFP/Getty Images)

April 2

At least four people injured by explosions amid protests against Russian occupation in Enerhodar, the town closest to the Zaporizhzhia plant.

Gunfire and explosions disperse a crowd in Enerhodar, Ukraine on April 2. (from Telegram)

April 26

Two guided missiles hit the city of Zaporizhzhia, less than 40 miles northeast of the plant. Energoatom claims the missiles flew at low altitudes directly above the nuclear power plant site. This is one of multiple local reports of hostilities in the vicinity of the plant.

A pillar of smoke rises from behind a residential building after missile strikes in Zaporizhzhia, Ukraine, on April 26. (Albert Koshelev/Ukrinform/Future Publishing/Getty Images)

June 6

Head of UN nuclear watchdog Rafael Grossi says he is determined to send an IAEA expert mission to Zaporizhzhia NPP to assess the safety of operation and working conditions. The IAEA spent weeks negotiating a trip with Ukraine and Russia.

July 19

A Ukrainian drone attack targets a Russian tent complex inside the plant’s main security exclusion zone, including a parked BM-21 ‘Grad’ rocket launcher. The attack led to a fire but did not damage the reactors or fuel storage areas.

Smoke billows upward as soldiers run out from tents on Zaporizhzhia NPP main site, Enerhodar, Ukraine. (Defense Intelligence of Ukraine)

Aug. 5-6

Explosions reported near an electrical switchboard caused one reactor to shut down temporarily, the IAEA said. Separately, rockets hit roughly 30 to 60 feet from a dry storage facility holding casks of spent nuclear fuel, according to Energoatom. Ukraine and Russia continue to accuse each other of shelling the Zaporizhzhia NPP in early August.

A rocket fragment is seen near the Zaporizhzhia nuclear power plant in territory under Russian military control, according to a photo still of a video released by Russian Defense Ministry Press Service on August 7. (Russian Defense Ministry Press Service/AP)

Aug. 11

IAEA chief Rafael Grossi tells the UN Security Council that the situation has “deteriorated rapidly to the point of being very alarming.” Ukraine’s representative accuses Russia of resorting to “manipulations and unjustified conditions for the site visit,” despite public declarations of cooperation.

International Atomic Energy Agency (IAEA) Director General Rafael Grossi addresses the United Nations Security Council via video conference on August 11 at UN headquarters. (Mary Altaffer/AP)

Aug. 12

Ukrainian authorities say the Ukrainian-controlled towns of Nikopol and Marhanets, across the Dnipro River from the plant, have been attacked by Russian rocket fire for several nights in a row.

Aug. 20-22

Shelling damages laboratory and chemical facilities inside the main plant complex and causes a temporary power cut-off from a backup thermal power station nearby, according to the IAEA, citing Ukrainian officials.

Aug. 24

Kyiv says since March, three Ukrainian workers have been killed by the Russian military, and at least 26 others have been detained on accusations of leaking information.

Aug. 25-26:

Ukraine informs the IAEA that a power blackout disconnected all six reactors from the national grid for the first time in the plant’s history after the last remaining power line was damaged. By August 27, it had been repaired.

A satellite image shows Zaporizhzhia nuclear power plant and fires nearby in Enerhodar on August 24. (European Union/Copernicus Sentinel-2 imagery/Reuters)

Around Aug. 28

Authorities in Ukrainian-controlled Zaporizhzhia city make iodine tablets available to residents as concern grows over a possible nuclear accident: the pills protect users against radioactive iodine and help prevent thyroid cancer.

Zaporizhzhia residents line up at the local administration office to receive iodine tablets in the city’s eastern Khortytskyi district on August 29. (Dmytro Smolienko/Reuters)

Sept. 1

After striking a hard-fought bargain with Ukrainian and Russian officials, a group of 14 international nuclear inspectors, including the IAEA head Rafael Grossi, arrives at the plant following a dangerous journey. Just hours before, Energoatom accused Russia of shelling the plant, which resulted in the fifth reactor shutting down and an activation of its emergency protection system.

Personnel from the International Atomic Energy Agency and the United Nations prepare to depart for Zaporizhzhia from a hotel in Kyiv, Ukraine, on August 31. (David Ryder/Anadolu Agency/Getty Images)

Source: IAEA, UN, The Institute for the Study of War with AEI’s Critical Threats Project, Janes, Energoatom, Ukraine’s State Nuclear Regulatory Inspectorate, Ukraine’s State Emergency Services, Defense Intelligence of Ukraine, Ukrainian Parliament Commissioner for Human Rights, regional Ukrainian authorities.

Credits

Reporting and writing: CNN Staff and Henrik Pettersson

Digital design and graphics: Natalie Croker and Byron Manley

Photo editor: Clint Alwahab

Editors: Anna Brand, Nick Thompson and Eve Bower