Mykhailo Poperechnyuk was driving towards the town of Nikopol, in southern Ukraine, earlier this month when he saw a barrage of Russian rockets streaking across the night sky.

The missiles were fired from what may be the most impregnable Russian positions along the entire front line: those around the Zaporizhia nuclear power plant just 5km away on the other side of the Dnipro river.

The Russian army seized the vast facility — the biggest in Europe, with six 950MW reactors — in the early weeks of its invasion, destroying a training office during the assault despite the obvious risks of damaging the plant and radiation leaks.

Since then, Ukrainian officials say, the Russians have stationed 500 troops and heavy weapons within the perimeter — in breach of International energy conventions — and are using the reactor blocks to protect against retaliatory fire.

“Imagine how cynical and immoral the Russians are,” said Poperechnyuk, a businessman and activist who is a member of Ukraine’s territorial defence forces. “They’re putting their artillery just behind the reactors so Ukrainian armed forces cannot respond.”

The people of Nikopol, a down-at-heel Russian-speaking steel town made up of factories and Soviet-era housing blocks, now live in the shadow of a power plant that has been turned into a Russian fortress. And there is little the country’s military can do either to attack or defend.

Since the salvo Poperechnyuk witnessed on July 14 there have been almost nightly Russian bombardments, frightening and exhausting residents — just as other towns and cities in the eastern Donbas region and southern Ukraine are being pulverised by Moscow’s assault.

Over two nights this week, the Russians fired 100 rockets at Nikopol and at one point air raid warnings sounded for 19 hours straight.

Among the scores of people waiting for food parcels at a charity centre in the town funded by Poperenchuk, the fear was palpable. The previous night five Russian missiles had hit several residential blocks and a factory, killing two people.

“It was scary,” said Lisa, a refugee from the southern city of Mariupol, where she spent seven weeks living in a basement amid a ferocious Russian bombardment. “We gave some antidepressants to our kid who was in tears at 4am. The kid was panicking so we hugged him very hard.”

“I’m shocked by what happened last night,” Zina Sidorenko, a pensioner, said of the latest attack, as tears welling in her eyes. She insisted she would not leave, but thousands already have.

Poperenchuk estimated that Nikopol’s population had halved from about 100,000 in the eight years since Russia annexed the Crimea peninsula and the separatist war broke out in the Donbas.

Tens of thousands have fled in the months since Moscow’s troops swept through southern Ukraine in the spring and took up positions just a few kilometres away.

“Before the rockets hit, business was bouncing back,” said Andriy Vezetelnik, who owns a restaurant, gym and a group of convenience stores in the town. Now “everyone has gone”.

Just across from his restaurant, dozens of mostly elderly locals had laid out on the grass a few meagre possessions for sale — some cups, a cracked casserole dish, a skipping rope. But there were few customers.

Mariya Poloz, operations manager for Poperenchyuk’s foundation, expressed a mix of trepidation and defiance at the prospect of a Russian attack.

“I’m a lawyer, a volunteer and a woman — I understand what they [Russian soldiers] can do if they come here. But a lot of people watch me. If they see me leave it’s a bad sign that there’s no hope here.”

In the nearby town of Oleksiyivka, Oksana Glushko was handing out food parcels to locals from outside the village hall. The municipal councillor hailed the extraordinary effort of ordinary Ukrainians to help not only their neighbours but also to support the war effort.

She and other activists have been delivering clothing, boots, car parts and 10,000 homemade ready meals to army units up to 250km away. They raised enough money to buy two vehicles and were now fundraising for a third. Glushko pulled out a ledger recording every delivery.

“Our people are generous,” she said. “Our people are our wealth.”

Ukraine’s armed forces have come to rely on crowdfunding and charity for vehicles, basic supplies and non-lethal equipment such as drones and computers. But it is the country’s military high command that distributes heavy weaponry. And Nikopol’s defenders do not have any.

“Now people from the top need to help us out,” said Volodymyr, a platoon commander in the territorial defence forces and veteran of the Donbas war.

Standing on the waterfront, the fortified nuclear power station visible in the distance, he said the Russians could try to launch an assault on Nikopol using helicopters and boats.

“But for now their strategy is to threaten civilians,” he said, pointing to a residential block on the crest of a hill. “Those people feel particularly exposed.”

Nikopol’s beach, a short strip of sand backed by a playground, was fenced off and mined to thwart a possible Russian amphibious assault. Along the road, at the SOK beach club, manager Svetlana was trying to make the best of a business she only bought last autumn.

A few guests lounged in the sweltering heat as others launched themselves from a pontoon into the greenish waters of the Dnipro.

“There’s good energy here,” she said, “it’s a kind of sacred place. Those people [the Russians] will have to fight hard with us.”