‘That still wouldn’t explain the reactor being so reluctant to start though, would it?’
‘No, but a hundred things could explain that. After all, we didn’t know much about that new moderator at the time.’
‘Can you tell us, in simple terms,’ pursued Arlen, ‘what your basic design mistake was?’ That familiar trick of his again, of looking over Self’s shoulder. ‘Was it, in fact, the moderator?’
‘Quite right. We thought it behaved exactly like pure graphite. It certainly did in our initial experiments. However, during my friendly chat with the electronic computer last night, I included some data which we hadn’t known at the time. It seems that under some conditions it undergoes a chemical change.’
Gatt jerked his eyes on to him. ‘I wonder… I mean, supposing that chemical change occurred again — in reverse, so to speak — when those rods were out, substantially changing the conditions so that the whole works was well over critical mass?’
Seff matched his gaze. ‘Yes, I’d thought of that, too. We’ll have to do some research on the moderator material. We dropped it after the Project 3 episode; so we still don’t know very much about it.’
‘Well, it’s very funny,’ said Manson, ‘that there should suddenly be all this interest in the moderator. It’s the first I’ve heard of it.’
‘What’s so funny about it?’ said Gatt coldly.
‘Well, it’s got such odd characteristics, hasn’t it? I mean, first you say it underwent some chemical change so as to reduce the mass below critical; then you say it had second thoughts and increased it again.’
Seff remarked, without emotion: ‘Well, no one knew the true effects of Wigner growth until after the piles at Windscale had been assembled. Their moderators were made of plain, ordinary graphite; yet people still got quite a shock when Number One Pile got all steamed up.’
‘I see,’ said Manson. ‘If in doubt, blame the moderator!’ He banged his fist angrily down on to the table, and when he spoke his voice had lost its banter. ‘Let’s face it, Seff. Your “moderator theory” smacks of third-rate science fiction. It’s unsubstantiated and, to say the least, extremely unlikely.’ Manson’s accusing eyes were unblinking, and somehow looked abnormally large. ‘I say you realised your miscalculation — perhaps, as you so helpfully suggest, a few days beforehand — plied yourself with a few whiskies and whipped a few enriched slugs from the other reactor.’ His laugh was a most unpleasant sound. ‘All that stuff about moderators! Well, which fits the facts best — your theory or mine?’
‘I must say, Manson,’ said Hargreaves, ‘I find your inferences extremely ill-timed.’
‘On the contrary,’ said Seff grimly, ‘I think they are singularly illuminating in a way. Not very factual, perhaps. But interesting, none the less. And, oddly enough, scientifically very plausible.’
Gatt smiled at Seff in an odd sort of way. ‘I for one,’ he commented, ‘am very glad it was said.’
Manson clutched at this straw. ‘Well, it may have sounded pretty unpleasant; but someone had to say it.’
This remark was entirely ignored.
Gresham came in quietly, and handed a copy of the new press release to the Director, who accepted it without comment. Gresham took his place at the table.
Gatt said: ‘All right. Since we all seem to be coming out in the open, I suppose I should admit that I was guilty myself of wondering whether, to be blunt, your judgment was affected by alcohol — though not exactly on the lines our friend has just suggested.’
‘Well, let’s have it.’
Gatt put two of his tablets in a glass of water and watched them fizz. ‘If you drive a car when you’ve had a few you don’t go wild. Under normal circumstances you drive very much the same as you do when sober. Only your reactions are slowed down. Instead of responding to an emergency in something like point four of a second, it takes you, say, double that time.’ He swirled the mixture round in the glass pensively. ‘Now, I was thinking of those control rods. I take it that when the reaction did not start as it should have done, you raised them right out of the pile, to absorb the minimum of neutrons and therefore allow them to do their stuff. Am I right so far?’
‘More or less. Actually, you can’t lift them right out. If the thing won’t cook when they’re raised about three-quarters of the way out, you can reckon that something’s cock-eyed somewhere.’
Gatt drank the liquid and pulled a face. ‘Beastly stuff! I see. And you lifted them to that extent?’
‘As I’ve already said, yes.’
‘I just want to get the chain of events firmly fixed in my mind. What happened then?’
‘I lowered the rods back to the half-way position and checked that the artificial neutron source was working. I found that it was.’
‘Ed Springle was with you, wasn’t he?’
‘Yes. Ed was there. In fact, the next thing I did was to tell him to lower the gas pressure, which he did. (Incidentally I phoned him yesterday about this — among other things — and his recollection of what happened in the Control Room checks with mine.) When Ed had reduced the pressure sufficiently, I then started to raise the control rods again.’
‘And what happened?’
‘Precisely nothing. Sweet damn-all.’
‘Then what?’
‘I had to do some hard thinking. Ed suggested he got us some food from the canteen, and he went off to get it.’
The Director said: ‘So you were left alone?’
‘As you say, I was left alone.’
Gatt said: ‘And the control rods were still raised nearly as far as they would go?’
‘That’s right. I was still hoping for the thing to make up its mind to co-operate.’
Gresham said: ‘Wasn’t that rather risky, old boy? I mean, if the confounded thing suddenly went into action?’
Seff drew hard on his cigarette, so that it made a little plop when he took it out of his mouth. ‘It was a risk, Frank, but a calculated one. Leaving the rods out gave it the best chance to start reacting, and you can stick them back in a matter of seconds — even without pressing the shut-down button.’
‘I’m sorry — this is probably a bloody-fool question. But wouldn’t it have been better to have assumed that something was wrong, put the rods back in, and left it till the next day? I mean, it wasn’t a matter of life and death, was it?’
‘As things turned out, it would have been a damn’ sight better, yes. But I hardly expected the pile to go clean off its head.’
‘Sorry, old chap. I suppose I’m being wise after the event.’
Manson had been keeping very quiet. But now he nerved himself to ask the obvious question. ‘What happened then, Jack?’
Seff spoke to the room in general, not to him. ‘Two things. Two things happened almost simultaneously. The output meter on the panel suddenly shot up to 20 megawatts — that’s twice the rated output — and Ed came in with the supper. The warning lights on the console were giving a very creditable impersonation of Piccadilly Circus at night, and the alarm bells started ringing. Ed shouted: “For the love of Mike, what’s happening?” I remember saying “Ed, the blowers!” and he just threw the tray on the floor and made a dive for the switches of the gas-cooling system. (Actually there was no need; they had started up automatically by then.) At the same time I pressed the shut-down button and waited for the needle of the output meter to drop back. But it didn’t.’
Gatt leaned forward in his chair and gazed very intently at him. The atmosphere in the room was stressed to maximum rated tension. ‘Are you absolutely sure that the meter didn’t go up to 20 megawatts before Springle came into the control-room?’