Fred Starr recollects... Lies, Damned Lies and Nuclear Power
October’s article about the closedown of Wylfa, Britain’s longest running Magnox reactor, brought to mind the first time I was lied to about nuclear power. I was on a sixth form visit to Calder Hall, the world’s first nuclear power station and the forerunner of the Magnox series. My innocent query was taken as a ruse to get the white-coated scientist, as he played around with a fuel rod, to admit that the real aim was the production of weapons-grade plutonium, not electricity.
Wylfa has been running for more than 40 years, thanks to the discovery of ‘rusty bolts corrosion’ in the first set of Magnox reactors. The rusty bolts phenomena is just one variant of breakaway corrosion, where after a few thousand hours of exposure to hot corrosive gases, oxidation rates shoot upwards. In Magnox, it was the coolant, CO2 at high pressure, that was the cause. I first heard about it through the national press, and though treated flippantly, like many nuclear embarrassments, a big reduction in operating temperatures was the only solution. This was imposed at Wylfa right from the start, hence its longevity. The Advanced Gas Cooled Reactor, or AGR, was the follow-on to Magnox, and although higher alloyed materials were used, breakaway corrosion was an issue with these, too, as temperatures were higher.
In the 1980s, over in British Gas, my team had switched to novel methods of power generation. We were developing a new gas turbine concept, where the vital piece of equipment was a pressurised heater fired by natural gas. The tubing was fabricated from a novel, extremely costly, ytteria dispersion strengthened, iron-aluminium-chromium alloy. At a metal temperature of 1,170°C it made the heater the hottest that had been built. Opposite numbers across Europe were enthusiastic, and made us the centrepiece of an EU programme, with money coming in to British Gas.
I was told that the oxidation resistance of the alloy was so good that long term testing would be a waste of time. In the back of my mind was what had happened to the nuclear people, who must have thought that CO2 could not be much more aggressive than air. And, being cynical, such tests were profitable. The walk down to the test bay to check temperatures was costed at three hours a day even though it only took twenty minutes.
We stuck one of the tubes into a two-metre-long furnace, so there was a considerable length at 1,200°C. After 6,000 hours the oxide was egg-shell smooth and just as thin, so we took the tube across to Belgium to show our sponsors just how well things were going. On getting back to London we restarted the test. Fortuitously, the furnace windings burnt out just 1,000 hours later, so we had the chance for another look. As the picture shows, it was horrifying, with the 30mm-diameter tube being festooned with thumb-sized clumps of black scale. We had got ourselves a virulent form of breakaway.
Joe Quadakkers, at the German Energy Centre in Juelich, came up with an explanation, as he too had started to experience the phenomenon. But his tests used tiny samples in which the breakaway was not that easy to see. I am absolutely certain we would have brushed his results to one side, unless we ourselves had experienced something so horrific. Inevitably, this has led to no end of PhDs!
That the Magnox programme made me aware of breakaway and need for long term testing doesn’t quite make up, for me, the deceit and obfuscations that have formed the backdrop to nuclear energy. But I am of an age that saw nuclear as getting us out of a coal-based economy, and I remain sympathetic. I date the demise of the British nuclear programme to the time when the rusty bolts issue hit the press. It’s been downhill since. Others have a different view of why things went wrong. I am looking forward to a Newcomen Society lecture in Manchester on 26 January titled The AGR programme - The wrong technology or the right technology badly managed? When I mentioned the talk to a nuclear insider, he snorted ‘Just one lecture? It needs at least five!’ For details about the lecture, visit bit.ly/1kYThF9