NEW cracks have been discovered in one of Scotland’s ageing nuclear reactors, raising radiation safety fears and resulting in a prolonged shutdown, the Sunday Herald can reveal.

Checks have detected fresh cracks in the graphite core of a reactor at Hunterston B in North Ayrshire. The reactor was taken offline on March 9, but is not now due to restart until May 1 at the earliest, more than a month later than originally planned.

The UK Government safety watchdog, the Office for Nuclear Regulation (ONR), is assessing whether the cracks render the reactor too dangerous to fire up. Its operator, EDF Energy, insists it will reopen, but critics say it should stay shut.

The integrity of the thousands of graphite blocks that make up the reactor core is vital to nuclear safety. They ensure that the reactor can be cooled and safely shut down in an emergency.

But bombardment by intense radiation over decades causes the blocks to start cracking. If they fail, experts say, nuclear fuel could overheat, melt down and leak radioactivity in a major accident.

Both the ONR and EDF told the Sunday Herald that new cracks had been found at Hunterston reactor number three during inspections in recent weeks, but they wouldn’t say how many, or how significant they were.

“We are currently assessing the safety case submitted by EDF after a planned outage identified a number of cracks in the graphite blocks that make up reactor three’s core,” said an ONR spokesman.

“Before we grant permission to EDF to restart reactor three we will require that an adequate safety case justifying further operation has been made. ONR has to formally permission the restart of the reactor.”

The ONR’s decision was still “a number of weeks” away, he added. “We will publish the justification behind our decision once it has been made.”

According to EDF’s website, Hunterston reactor three was originally due back online on March 30 after a “graphite inspection outage”. But this has been repeatedly postponed to April 6, April 19, April 24 and now May 1.

The company confirmed that it had “discovered cracks in the inspections during the current outage”. It promised to report the details to the local site stakeholder group after the reactor was restarted.

“As part of the normal ageing process we expect to see defects occurring in some of the graphite blocks that make up the reactor core of our plants,” said an EDF spokeswoman.

“This phenomenon is understood and is recognised in our operational safety cases which are agreed with the nuclear safety regulator. We have prepared well for this; we have a £100 million graphite research programme.”

She added: “Hunterston B remains safe to operate and will be back online once the current outage is completed. We will, as normal, consult with our regulators before returning the reactor to service.”

Hunterston reactor three, which has been running since 1976, is one of the oldest of its kind. It’s where “graphite defects are most advanced” and hence has more inspections than other reactors, said the EDF spokeswoman.

But Pete Roche, a nuclear critic and consultant in Edinburgh, warned that EDF’s optimism that the reactor will restart could be misplaced. “Cracks could prevent control rods from being inserted causing the nuclear fuel to overheat, potentially resulting in a nuclear accident,” he said.

It was “all a bit of a gamble”, he argued. “Hunterston is already 42 years old - when it was only expected to operate for 30 or 35 years. It is clearly time to say goodbye to reactor three.”

Expert nuclear engineer John Large also suggested that the reactor should be closed down. “The core at Hunterston may now be in such a poor structural state that its collapse during a relatively modest earthquake could result in a nuclear fuel meltdown and significant radioactive release,” he said.

“All that EDF can do is permanently shut Hunterston, there being no alternative means to remedy this very serious situation.”

Professor Paul Bowen, a metallurgist from the University of Birmingham who advises the ONR, thought that the body was likely to insist on more frequent inspections rather than reactor closure. “I’m absolutely confident that the regulator will take a very conservative position,” he said.

According to Rita Holmes, a local resident who chairs the Hunterston site stakeholder group, people were worried. “The local communities are unhappy that the reactor has any cracks, and certainly not happy that one with a growing number of cracks could be allowed to continue generation,” she said.

The Scottish Greens MSP for the west of Scotland, Ross Greer, warned that the discovery of new cracks would cause widespread concern. “EDF and the regulator must explain what has been found, and seek the community's views, before putting this reactor back online,” he said. </s> The Fukushima nuclear power plant’s (NPP) operator has detected extremely high radiation levels at a damaged reactor at the Fukushima power plant in Japan.

Radiation levels that are lethal after brief exposure were found inside the second reactor on Thursday

Tokyo Electric Power Company also found a hole which was likely caused by melted nuclear fuel was also discovered at the reactor.

Radiation levels of up to 530 Sieverts per hour were detected inside an inactive Reactor 2 at the Fukushima Daiichi nuclear complex damaged during the 2011 earthquake and tsunami catastrophe, Japanese media reported on Thursday citing the plant operator, Tokyo Electric Power Company (TEPCO).

A dose of about 8 Sieverts is considered incurable and fatal.

A hole of no less than one square meter in size has also been discovered beneath the reactor’s pressure vessel, TEPCO said. According to researchers, the apparent opening in the metal grating of one of three reactors that had melted down in 2011, is believed to be have been caused by melted nuclear fuel that fell through the vessel.

The iron scaffolding has a melting point of 1500 degrees, TEPCO said, explaining that there is a possibility the fuel debris has fallen onto it and burnt the hole. Such fuel debris have been discovered on equipment at the bottom of the pressure vessel just above the hole, it added.

The latest findings were released after a recent camera probe inside the reactor, TEPCO said. Using a remote-controlled camera fitted on a long pipe, scientists managed to get images of hard-to-reach places where residual nuclear material remained. The substance there is so toxic that even specially-made robots designed to probe the underwater depths beneath the power plant have previously crumbled and shut down.

However, TEPCO still plans to launch further more detailed assessments at the damaged nuclear facility with the help of self-propelled robots.

Earlier this week, hopes for a more efficient cleanup at Fukushima were high, as the plant operator announced a portion of nuclear fuel debris responsible for a lot of the lingering contamination from six years ago may have finally been found. </s> An area of the Fukushima Daiichi nuclear plant is showing record levels of radiation, the highest since the complex suffered a nuclear meltdown initiated by a tsunami in 2011. The plant operator Tokyo Electric Power Company (Tepco) announced that the containment vessel of the No 2 reactor showed radiation levels of up to 530 sieverts per hour, which can kill a human in under a minute.

Previous analysis of the area back in 2012 showed records of 73 sieverts per hour in the same area. The new discovery, which was made on 30 January, is based on images captured by three manned cameras which were mounted on a robot to gather information about the state of the reactor.

Images also indicated a hole below the pressure vessel, Nekkei Asian Review reported. According to Tepco, the hole may have been the result of nuclear fuel that entered the vessel as it overheated. Loss of reactor cooling functions in the days following the tsunami could have led to the melting of the walkway.

"It may have been caused by nuclear fuel that would have melted and made a hole in the vessel, but it is only a hypothesis at this stage," Tepco spokesman Tatsuhiro Yamagishi told AFP on 3 February.

"We believe the captured images offer very useful information, but we still need to investigate given that it is very difficult to assume the actual condition inside."

The radiation levels could effectively shut down TEPCO's robots that are being used for the investigation in under two hours, AFP reported. However, the operators plan to extend the probe and check conditions by sending a robot to the bottom of the reactor containment vessel.

The Fukushima plant suffered three meltdowns as a result of the tsunami on 11 March, 2011 which destroyed the emergency generators which provided power to cool the reactors. The accident led to one of the worst nuclear disasters since Chernobyl in 1986, and last year, researchers were able to detect radiation from the site all the way in Oregon, USA.
Cracks are discovered in the core of Hunterston B nuclear power station in North Ayrshire, Scotland. The Office for Nuclear Regulation is investigating to determine if the reactor is now too dangerous to restart.