An analysis by NPR of video and photographs of the attack and its aftermath shows that the assault by Russian forces was far more dangerous than first thought.

A review of a security camera video shows that Russian forces fired heavy weapons in the direction of the reactor buildings, which housed dangerous nuclear fuel. The administrative building in front of the reactor complex was destroyed by Russian fire. A video from inside the plant shows damage and a possible Russian shell that landed less than 250 feet from the Unit 2 reactor building.

The security camera footage shows Russian troops firing rocket-propelled grenades into the main administrative building at the plant and turning away Ukrainian firefighters as a fire raged out of control in a nearby training building.

There is damage to an office at the Nuclear Power Plant. NPR was able to verify the location of the main administrative building at the front of the facility using buildings visible outside the window.

Energoatom

The International Atomic Energy Agency (IAEA), which acknowledged the seriousness of the assault, emphasized that the action took place away from the reactor, stands in stark contrast to the evidence. The director-general of the IAEA made a reference to a single projectile hitting a training building next to the reactor complex in a news conference immediately after the attack.

Grossi told reporters at the March 4 briefing that the safety systems at the plant were not affected.

The training building was the only part of the site that was hit by Russian forces. The security footage shows damage to the Unit 1 reactor building, the transformer at the Unit 6 reactor and the spent fuel pad, which is used to store nuclear waste. There is a high-voltage line outside the plant. Two lines were damaged in the attack.

The director of nuclear power safety at the Union of Concerned Scientists says that the video is very disturbing. While the types of reactor used at the plant are far safer than the one that exploded in Chernobyl in 1986, the Russian attack could have triggered a meltdown similar to the one that struck Japan in 2011.

It is insane to subject a nuclear plant to this kind of attack.

In a news conference on Thursday, Grossi said that he had met with Ukrainian and Russian officials but failed to reach an agreement to avoid future attacks on Ukraine's other nuclear plants.

The assault

The nuclear plant was preparing for a fight. The facility was described in a news release as operating normally, with a Ukrainian military unit ready for combat.

The Russian decision to move on the plant was clearly premeditated according to an analyst who helped NPR review the video.

Hadavi says that it was planned and involved around 10 armored vehicles as well as two tanks. That is more powerful than a mission that might have stumbled across the plant by chance.

Someone began streaming the security footage of the plant on its YouTube channel. Russian forces began a slow and methodical advance on the plant. The column of armored vehicles, led by the tanks, used spotlights to cautiously approach the plant from the southeast along the main service road to the facility.

A missile from Ukrainian forces disabled one of the two tanks that led the column.

A firefight lasted for two hours at the plant. Russian forces returned fire after the tank was disabled, hitting a transmission line. Two of the high-voltage lines were damaged in the attack. The lines are essential to safe operations.

Russian forces moved into the parking area near the front gate and began shooting.

The main administrative building and the training center were the targets of the fire. Russian forces fired into the nuclear complex at various points during the battle.

It is not clear if the Russian troops were trying to strike more sensitive sections of the plant or if they were returning fire from the Ukrainian forces. The shooting was not accidental.

Hadavi says that the fire is very concentrated. They want to hit Point A, Point B, Point C and Point D.

The reactor compartment of Unit 1 sustained damage after the battle, according to the State Nuclear Regulatory Inspectorate of Ukraine. Two shells landed in an area that used to hold old nuclear waste to the north of the battle. Further damage was reported to the power transformer for the Unit 6 reactor.

At one point in the video, Russian forces are shown directing their firepower towards Unit 6 and the spent fuel area.

The Russian troops were disciplined through most of the attack. Some Russian soldiers seemed to beindiscriminately discharging rocket-propelled grenades towards the main administrative building at the end of the fight. A person was seen stepping from behind an armored vehicle and firing a weapon into the upper floors of a building. Five rocket-propelled grenades were thrown into the facility.

Firefighters denied entry

The fighting ended at A Russian-built MRAP armored vehicle with a gray paint job resembling those used by the Russian National Guard wasReinforcements arrived.

Firefighting vehicles arrived from the nearby town of Enerhodar at around 2:50 a.m. Russian forces forced the firefighters to turn around as the fire raged in the training building.

The damage

In the days after the assault, the Ukrainian state-owned utility that ran Zaporizhzhia released photos of the damage to the site on the social media platform Telegram. A short video shows a Russian shell on an elevated walkway leading to the Unit 2 reactor building.

Hadavi says the shell is similar to some 100mm and 125mm weapons used by Russian armored vehicles and tanks. The video shows two holes that were punched through the walkway ceiling and damage to the steel beams holding up the roof.

The Unit 2 reactor building is close to the location of the possible shell and the damage.

The building used to handle radioactive waste is next to the walkway. The building is not as strong as the nuclear reactor buildings are. Had it been hit, there would have been a chance of a radioactive release.

It was a close call, according to Bielefeld.

There are photos of battle damage to offices at the plant. The main administrative building is located at the front of the facility.

The damage appears to have been to some of the less hardened points within the nuclear plant, according to photos and damage assessments by Ukrainian officials and the IAEA. Unlike office buildings and elevated walkways, the reactor itself and its spent fuel are sealed within a thick steel containment vessel that would survive a lot of damage.

He says that the systems that keep the reactor safe are not hardened against an attack. The control rooms are not designed to operate in a war zone, the cooling systems rely on exterior pipework, backup generators are kept in relatively ordinary buildings, and vital electrical yards are out in the open.

There is a second office in the main building. There is a Russian flag and a Banner of Victory visible through the window.

Energoatom

The site of the worst nuclear disaster in the world, Chernobyl, has an inherently safer design than the ones at Zaporizhzhia, according to Lyman.

If the firefight had damaged more of the plant's critical subsystems, the situation could have been dire.

He says that in a couple of hours you have core damage starting and a situation that is potentially irreversible.

The electrical and cooling systems at the Fukushima Daiichi Nuclear Power Plant were disabled in 2011. The nuclear fuel eventually melted because the three operating reactor's core overheated. The radioactive material spilled into the environment when the containment vessels broke. Over 100,000 people were forced to leave their homes for a period of time.

"Dangerous idiocy"

That didn't happen at the Zaporizhzhia nuclear plant. Russian state media showed off the capture of the plant on Wednesday while carefully detailing the damage done by Russian troops. The nuclear inspectorate of Ukraine says that the two reactor at the site have been rendered useless by the fighting. Repairs to the damaged Unit 6 transformer are being hampered by a lack of personnel and parts.

The regulator said in a statement that incomplete and/or untimely implementation of maintenance measures for equipment important to safety can decrease its reliability and in turn lead to its failure and emergencies.

He is worried about the firefights at the nuclear power stations. The director of the Rivne Nuclear Power Plant told NPR that Ukrainian forces were prepared to defend the plant if Russian troops tried to take it. Russian forces are moving towards the South Ukraine Nuclear Power Station.

I hope this will be the last time we talk about these things.

He is worried that a more serious accident could be just a matter of time without some sort of rules of engagement.

He says that everyone knows that nuclear reactor are not designed to be impervious to all-out military assaults.

Tim Mak and Daniel Wood contributed to the report.