An aerial view from a plane shows a New Safe Confinement (NSC) structure over the old sarcophagus covering the damaged fourth reactor at the Chernobyl Nuclear Power Plant during a tour to the Chernobyl exclusion zone, Ukraine April 3, 2021. Ukraine International Airlines made a special offer marking the 35th anniversary of the Chernobyl nuclear disaster. Tourists get a bird's eye view of abandoned buildings in the ghost town of Pripyat and the massive domed structure covering a reactor of the Chernobyl Nuclear Power Plant that exploded on April 26, 1986. Picture taken April 3, 2021. REUTERS/Gleb Garanich

Passengers are seen onboard a plane during a tour to the Chernobyl exclusion zone, Ukraine April 3, 2021. Ukraine International Airlines made a special offer marking the 35th anniversary of the Chernobyl nuclear disaster. Tourists get a bird's eye view of abandoned buildings in the ghost town of Pripyat and the massive domed structure covering a reactor of the Chernobyl Nuclear Power Plant that exploded on April 26, 1986. Picture taken April 3, 2021. REUTERS/Gleb Garanich

An aerial view from a plane shows a New Safe Confinement (NSC) structure over the old sarcophagus covering the damaged fourth reactor at the Chernobyl Nuclear Power Plant during a tour to the Chernobyl exclusion zone, Ukraine April 3, 2021. Ukraine International Airlines made a special offer marking the 35th anniversary of the Chernobyl nuclear disaster. Tourists get a bird's eye view of abandoned buildings in the ghost town of Pripyat and the massive domed structure covering a reactor of the Chernobyl Nuclear Power Plant that exploded on April 26, 1986. Picture taken April 3, 2021. REUTERS/Gleb Garanich

A pilot wearing a protective face mask addresses passengers onboard a plane during a tour to the Chernobyl exclusion zone, Ukraine April 3, 2021. Ukraine International Airlines made a special offer marking the 35th anniversary of the Chernobyl nuclear disaster. Tourists get a bird's eye view of abandoned buildings in the ghost town of Pripyat and the massive domed structure covering a reactor of the Chernobyl Nuclear Power Plant that exploded on April 26, 1986. Picture taken April 3, 2021. REUTERS/Gleb Garanich

Passengers wear protective face masks onboard a plane during a tour to the Chernobyl exclusion zone, Ukraine April 3, 2021. Ukraine International Airlines made a special offer marking the 35th anniversary of the Chernobyl nuclear disaster. Tourists get a bird's eye view of abandoned buildings in the ghost town of Pripyat and the massive domed structure covering a reactor of the Chernobyl Nuclear Power Plant that exploded on April 26, 1986. Picture taken April 3, 2021. REUTERS/Gleb Garanich

Passengers board a plane during a tour to the Chernobyl exclusion zone at the Boryspil International Airport outside Kyiv, Ukraine April 3, 2021. Ukraine International Airlines made a special offer marking the 35th anniversary of the Chernobyl nuclear disaster. Tourists get a bird's eye view of abandoned buildings in the ghost town of Pripyat and the massive domed structure covering a reactor of the Chernobyl Nuclear Power Plant that exploded on April 26, 1986. Picture taken April 3, 2021. REUTERS/Gleb Garanich

Passengers board a plane during a tour to the Chernobyl exclusion zone at the Boryspil International Airport outside Kyiv, Ukraine April 3, 2021. Ukraine International Airlines made a special offer marking the 35th anniversary of the Chernobyl nuclear disaster. Tourists get a bird's eye view of abandoned buildings in the ghost town of Pripyat and the massive domed structure covering a reactor of the Chernobyl Nuclear Power Plant that exploded on April 26, 1986. Picture taken April 3, 2021. REUTERS/Gleb Garanich

An aerial view from a plane shows the Chernobyl Nuclear Power Plant during a tour to the Chernobyl exclusion zone, Ukraine April 3, 2021. Ukraine International Airlines made a special offer marking the 35th anniversary of the Chernobyl nuclear disaster. Tourists get a bird's eye view of abandoned buildings in the ghost town of Pripyat and the massive domed structure covering a reactor of the Chernobyl Nuclear Power Plant that exploded on April 26, 1986. Picture taken April 3, 2021. REUTERS/Gleb Garanich

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

Cooks from Euskal Gozogileak (Basque confectioners) create a full-sized reproduction of Picasso's Guernica made with chocolate, ahead of the 85th anniversary of the bombing of the town, in Lezo, Spain, April 20, 2021. Picture taken April 20, 2021. REUTERS/Vincent West

People pause to photograph blooming spring flowers and trees on Earth Day in Manhattan's Riverside Park in New York City, New York, U.S., April 22, 2021. REUTERS/Mike Segar

A man jogs a path through blooming spring flowers and trees on Earth Day in Manhattan's Riverside Park in New York City, New York, U.S., April 22, 2021. REUTERS/Mike Segar

A woman walks a path through blooming spring flowers and trees on Earth Day in Manhattan's Riverside Park in New York City, New York, U.S., April 22, 2021. REUTERS/Mike Segar

People watch historic footage of late Chinese chairman Mao Zedong at an exhibition marking the 100th founding anniversary of the Chinese Communist Party (CCP) in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

People pose for pictures in front of an installation that includes an image of Chinese President Xi Jinping at an exhibition marking the 100th founding anniversary of the Chinese Communist Party (CCP) in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

People swear an oath to the Chinese Communist Party (CCP) in front of an installation that includes an image of Chinese President Xi Jinping at an exhibition marking the party's 100th founding anniversary in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

People stand in front of the Chinese national flag at an exhibition marking the 100th founding anniversary of the Chinese Communist Party (CCP) in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

People gather for a group photo at an exhibition marking the 100th founding anniversary of the Chinese Communist Party (CCP) in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

People stand in front of a painting depicting late Chinese chairman Mao Zedong inaugurating the People's Republic of China at Tiananmen Square at an exhibition marking the 100th founding anniversary of the Chinese Communist Party (CCP) in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

A person takes a picture of an installation that includes an image of Chinese President Xi Jinping at an exhibition marking the 100th founding anniversary of the Chinese Communist Party (CCP) in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

The emblem of the Chinese Communist Party (CCP) illuminates the ceiling of an exhibition marking the party's 100th founding anniversary in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

A man takes a picture of the emblem of Chinese Communist Party (CCP) at an exhibition marking the party's 100th founding anniversary in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

People walk past a painting depicting late Chinese chairman Mao Zedong inaugurating the People's Republic of China at Tiananmen Square at an exhibition marking the 100th founding anniversary of the Chinese Communist Party (CCP) in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

The emblem of the Chinese Communist Party (CCP) illuminates the ceiling of an exhibition marking the party's 100th founding anniversary in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

People hold the Chinese national flag as they pose for a group picture at an exhibition marking the 100th founding anniversary of the Chinese Communist Party (CCP) in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

People stand in front of a display of historic international issues of the Communist Manifesto at an exhibition marking the 100th founding anniversary of the Chinese Communist Party (CCP) in Beijing, China, April 22, 2021. REUTERS/Thomas Peter

A view shows the abandoned city of Pripyat near the Chernobyl Nuclear Power Plant, Ukraine, April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

A child's gas mask is seen in a kindergarten near the Chernobyl Nuclear Power Plant in the abandoned city of Pripyat, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

A vintage doll, which was placed by a visitor, is seen on a bed at a kindergarten near the Chernobyl Nuclear Power Plant in the abandoned city of Pripyat, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

Toys are seen in a kindergarten near the Chernobyl Nuclear Power Plant in the abandoned city of Pripyat, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

A view shows the abandoned city of Pripyat near the Chernobyl Nuclear Power Plant, Ukraine, April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

Remains of burnt houses are seen in the abandoned village of Poliske in the Chernobyl zone, Ukraine April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

An elk is seen in a burnt forest in the Chernobyl zone, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

Constructions of a Soviet made over-the-horizon (OTH) radar system "Duga" are seen near the Chernobyl Nuclear Power Plant, Ukraine, April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

An employee is seen in a control centre of the stopped third reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An employee walks through a corridor of the stopped third reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An employee is reflected in a control centre of the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An employee is seen in the reactor hall of the stopped third bloc at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An employee walks at a control centre of the damaged fourth reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An employee gestures in a corridor near the damaged fourth reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An employee walks through a corridor of the stopped third reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An employee undergoes a radioactive contamination check near the damaged fourth reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An employee walks down the stairs at the stopped third reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

A Przewalski's horse is seen in a burnt forest in the Chernobyl zone, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

A house is seen in the abandoned village of Zalissya near the Chernobyl Nuclear Power Plant in Ukraine April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

A calendar is seen on the wall in a house in the abandoned village of Zalissya near the Chernobyl Nuclear Power Plant, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

An interior view shows the house in the abandoned village of Zalissya near the Chernobyl Nuclear Power Plant, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

An interior view shows the house in the abandoned village of Zalissya near the Chernobyl Nuclear Power Plant in Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich