The International Atomic Energy Agency, an arm of the United Nations that sets safety standards for the world, says that the Chernobyl nuclear power plant in northern Ukraine and the nation's 15 operating reactor are safe and secure.

The only real issue is if a nearby target got hit and caused some damage. I don't think Russia would target a plant.

In 1986, the Chernobyl nuclear power plant had a meltdown that sent radioactive clouds over Europe and left a wasteland of contaminated soil. The work force at the Chernobyl plant closely watches the safety of the Unit 4 reactor, which exploded and caught fire in 1986. The abandoned plant is surrounded by an exclusion zone that restricts public access.

One of Russia's main invasion routes is the plant, which is some 10 miles from Belarus. Western experts said it was in Moscow's interest to keep the reactor and electrical system running so that regime change wouldn't ruin the country.

There is a risk of a direct hit, according to R. Scott Kemp, a professor of nuclear science at the Massachusetts Institute of Technology.

The biggest threat is the degradation of the power grid in Ukraine, which could cause cascading power failures.

The Russian invasion and military takeover of Chernobyl may cause another ecological disaster if the war continues, according to the Ukrainian government.

Nuclear experts did not raise any strident alarms. The director general of the International Atomic Energy Agency, based in Vienna, said in a statement on Thursday that his Ukrainian counterpart reported that the nation's 15 nuclear power plants were operating safely. The Ukrainian body reported no casualties or destruction at the Chernobyl site.

On Friday, the agency noted reports of higher radiation readings at the Chernobyl site, and quoted the nuclear body of Ukraine as saying that the readings may have been caused by heavy military vehicles.

The agency said that the readings are low and remain within the operational range measured in the Exclusion Zone.

According to the international atomic agency, Ukraine gets more than half of its electricity from its reactor.

Two of the four operational nuclear sites in Ukraine are in the western part of the country, far from Russia's main invasion routes. The southern region is close to the ongoing military strikes.

The Zaporizhzhia Nuclear Power Plant is the largest of Ukraine's atomic plants. It is on the Dnieper River in the north. The peninsular part of southern Ukraine was annexed by Russia in the summer of 2014).

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What is the root of this invasion? Russia considers Ukraine to be within its sphere of influence, and it is worried that the country might join NATO or the European Union. The United States and Europe give financial and military aid to Ukraine.

Are these tensions starting now? The Russian military crossed into Ukrainian territory after the overthrow of their Russia-friendly president. There was a cease-fire in 2015, but fighting continues.

How has the Ukrainians responded? The state of emergency was declared after cyberattacks knocked out government institutions. Volodymyr Zelensky declared martial law after the attacks. The foreign minister called for the world to stop the attacks.

The World Nuclear Association, an industry trade group based in London, reported that the Ukrainian state-owned nuclear power firm had detailed some of the rules meant to enhance the safety and security of its nuclear plants.

The group said that early this month, as Russia built up its forces around Ukraine, Petro Kotin, the acting president of Energoatom, described how a bombing would prompt a nuclear plant to shut down and said that its operators would unload its radioactive fuel.

If a plant lost its electrical power, backup generators would kick in to keep the reactor running. The stock of diesel fuel located at nuclear power plants significantly exceeds the established standards, he was quoted as saying.

The reactor vessels and the surrounding containment areas of the Ukrainian power plants were designed to survive an aircraft crash.

On Friday, the World Nuclear Association reported that the security divisions of Ukraine's plants are on high alert.