My own personal Fukushima

The NPL-Cranfield Primary Acoustic Thermometer

The NPL-Cranfield Primary Acoustic Thermometer

On Thursday we began taking data which marks the end of a four year quest to make the most accurate measurement of temperature humanity has ever made. It has been hard, and the last few  months have been especially difficult, working through Christmas and New Year and struggling to overcome some significant problems. But on Friday, the data we had collected overnight looked very sweet – and we just needed to do exactly the same thing 44 more times in order to finish. The apparatus temperature was stable and uniform  to within ±50 micro kelvin, the pressure was stable at 650,000 pascal and known to within a few pascal. So inside the bustle of the laboratory – humming pumps and flashing lights – was a perfectly calm and stable region in which we could carry out our experiments. I even found myself uttering the fateful words:  ‘What could possibly go wrong?“…

At 4:30, the power failed, for about 1 second. My colleague Gavin Sutton and I raced from our office to the lab, and within 30 seconds were trying to sort things out. It was all very confusing. Temperatures and pressures were changing and it was very hard to figure out exactly which pieces of apparatus had been affected. For example, some equipment is protected by an Uninterruptible Power Supply (UPS), and other pieces of equipment are not. The computers had re-started and some equipment wouldn’t respond to computer controls and overall it took several hours to gain control again, and even then there was a sting in the tail. One of the Mass Flow Controllers (a kind of automatic valve that lets a precisely controllable amount of gas through) had broken, but we didn’t know because that particular controller was not used when the pressure was stable – it was only used when we changed the pressure. So it was only later  on  that I discovered the fault. After several hours in the lab yesterday and today, and a fair amount of monitoring from home, I think we will be able to make repairs on Monday and limp along.

Now the details don’t matter – but this is a piece of apparatus that Gavin and I know very well. Together with our colleague Robin Underwood, we have built it together over several years and written every line of computer code which controls it. But as we struggled to put things right, my thoughts drifted to the workers at  Fukushima who just one week before must have been having a normal Friday afternoon. Perhaps they were reflecting on how well the reactor was working. And then an Earthquake struck. Alarms would have been sounding everywhere and nothing would have been normal. They would have rushed to control panels and seen that the control rods had dropped in place and that emergency cooling circuits had activated. After around 20 minutes – when they were probably just beginning to regain some composure – they were hit with a tsunami…

Now I don’t put the efforts of Gavin and myself into the same category as the efforts of the workers at Fukushima. But we did share that sense of instantly shifting from complacency to acting urgently without fully knowing what has happened. So I feel as though we glimpsed a small fraction of what the workers at Fukushima must have felt. And my thoughts went out to them. I have been reading more about the events that happen to a nuclear reactor when it is shut down, and it seems that the first few minutes are critical. And so although it would be something  of an understatement to say that they have been having a ‘bad week’, their actions in the first minutes after the earthquake, may have stopped the week from being a whole lot worse.

2 Responses to “My own personal Fukushima”

  1. Richard Says:

    An interesting perspective- I like! A lab with the power going down is unsettling at the best of times, but that sounds like a particularly good incident you had.

    That was some power blip if it took out a mass flow controller. Would this be a good time to mention that the normal types don’t *totally* seal when they’re switched on (IIRC)?

    • protonsforbreakfast Says:

      Thank Richard. The fault is that the MFC is closed when its closed, but when it is set to any value other than zero, then it goes full open. This means all the gas just rushes straight out of my resonator!

      Hope everything is well at the MO.

      All the best


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