The Chernobyl nuclear disaster in 1986 is widely believed to have caused the death of at least 4,000 people, with a further untold number of children born with abnormalities.

The explosion forced the evacuation of more than 100,000 Ukrainians and Belarussians, laying waste an area measuring 3,000 sq miles (7,769 sq km) that remains uninhabitable to this day.

Within weeks of the fire that started at about 01:30 BST on 26 April, 30 years ago, hill farmers across north Wales were also dragged into the developing crisis.

Heavy rain in April and May drenched higher ground with alarming quantities of radioactive caesium and iodine. The authorities reacted by imposing a blanket ban on the sale of all farm animals. Panic spread.

Glyn Roberts, now the president of the Farmers Union of Wales, said: "At the time we were worried what effect the fallout would have on our health. My wife was expecting and we were worried what effect it would have on our children, that was the prime issue.

"The news was difficult to believe, and it made you think 'how safe is nuclear energy production?'.

"I remember I was in Ruthin market when we were told that we could not sell any of our lamb or beef. That was when it hit home, and there was quite a bit of accumulative cash flow problems."

Image caption Glyn Roberts' farm was one of 344 in Wales to be put under restrictions

Mr Roberts, and others at the time, felt the government's response was too slow, and matters came to a head at a public meeting in Llanrwst, Conwy county, when representatives of the Welsh Office were not allowed to leave until firm promises of compensation were given.

"When someone said that the issue was not going to be addressed that night, the crowd outside went a bit wild," he said.

"Following that, Nicholas Edwards the Secretary of State came to this farm and we explained our situation.

"From there things did move on a bit and we were told that there was going to be some compensation."

In total, 344 Welsh farms were put under restrictions, with animals' radiation levels monitored before they were allowed to be sold at market.

The number of failing animals peaked in 1992, but some still recorded higher levels of caesium as recently as 2011.

'Abnormal lambs'

A year later, the authorities decided the numbers were then insignificant and there was no reason to continue the monitoring. This saved the taxpayer about £300,000 a year.

Some farmers were in favour of further monitoring, if only to maintain the public's trust in Welsh meat, but the majority approved and welcomed the end of a long saga that started 1,500 miles (2,414km)away deep, in the former Soviet Union.

The following years were still full of concern for many Welsh hill farmers.

"Every farm has some abnormal lambs born, but I believe that for the first years after Chernobyl there were more abnormalities in the lambs," Mr Roberts said. "I have no evidence, but that is what I feel."

But at least the Welsh farmers were able to stay in their homes and keep their livestock and livelihoods.

It was a different story in northern Ukraine, where anyone living within a 30-mile (48km) radius of the power plant had to leave their homes.

As well as the cities of Chernobyl and Pripyat, that meant the emptying of villages and hamlets.

One of the largest was Parashev, some 10 miles (16km) east of the power station.

Maria Adnamova was born there and, after a few years of enforced exile, she, her husband and a few other unhappy souls decided to return.

Image caption Maria Adnamova is one of just five people living in Parashev

But the world had moved on, and Parashev with its hundreds of empty homes, shops, schoolroom and council offices rotted away before their eyes.

Today, the widowed Mrs Adnamova, 81 years old and with failing health, is one of just five people existing in Parashev.

A translator for Mrs Adnamova explained why the threat of Chernobyl's poisoned legacy was not enough to keep her from her home.

"They were evacuated late on 3 May. They were given a house some place in the Kiev region, quite far from here, but she did not like the climate. She decided to return, because her parents and grandparents live here. She will die on her own land."

The power station stands at the centre of a sprawling complex of buildings and can be seen from many miles away.

The fourth reactor, the cause of so much suffering, is encased in a crumbling concrete shell, built in the years immediately after the disaster.

Image caption The fourth reactor will eventually be encased in this 'sarcophagus'

Its usefulness has expired and will be replaced by the so-called sarcophagus, the international community's expensive answer to the vexing issue of how to deal with the problem of reactor number four.

At first glance, in the bright spring sunshine, it could be mistaken for the Wales Millennium Centre.

Built by the Americans it will, later this year, be slid along the ground, a few meters at a time, before finally engulfing the crumbling reactor and its still poisonous contents.

No trip to Chernobyl is complete without a visit to Pripyat. A few days before we filmed, a minibus of Welsh football fans also made the journey.

A city of almost 50,000 people at the time of the disaster, Pripyat was, according to our guide, the model of Soviet efficiency.

Image caption Pripyat was evacuated before the fairground was ever used

Today, the countless empty tower blocks, supermarkets, swimming pool, hotel and shops, and the fairground that never opened, is a permanent reminder of the dangers associated with the nuclear industry. Pripyat was emptied in just a few days, and will never again be called home.

On the outskirts of the Welsh capital lives one of the world's most renowned nuclear physicists, an expert on the dangers posed by radiation.

Prof Glyn O Phillips, a consultant to the International Atomic Agency for more than 20 years, specialising in the effects of radiation on the human body, is an ardent supporter of nuclear energy production, but worried the Chernobyl story may not yet be over in Wales.

Image caption Prof Glyn O Phillips said it was possible the effects of Chernobyl could be felt in Wales for generations to come

"The word that they use officially is low risk. But risk is a very difficult question when you deal with low level radiation," he said.

"There is great uncertainty and extrapolation is only possible with time and we will only see in the next generation or generation after that whether there are any significant effects to be demonstrated then."

On Tuesday in Chernobyl, and also in Pripyat, people will stand to remember those who died, the lives that were ruined and the dreams that were lost with them.

Here in Wales, the disaster's legacy may be felt for generations to come.