‘I’m glad you think so.’
‘I should really get on with the job at hand, you know. I wouldn’t like to fall behind schedule.’
‘What schedule is that?’
‘The repair schedule. I mean, this is a high-security environment, isn’t it? I’m sure you just want us out of here as soon as possible.’
‘Yes, I suppose you must be right. All the same, I’ve enjoyed our little talk.’
‘Me too.’
‘It’s been most helpful to me.’
‘Good, I’m glad.’
‘There’s not a great deal of opportunity to discuss things out here. To reflect upon the basis of all certitude. Ideas and things.’
‘I can imagine.’
‘Yes, that’s really what it’s all about, isn’t it? Imagining. Anyway, please let me know if I can be of any further assistance to you all.’
‘Thanks a lot,’ said Simou, who couldn’t quite believe in the beneficence of the Descartes computer any more than he could accept the idea of a benign and concerned God.
‘No really, I’m quite sincere.’
‘I think I know you are,’ said Simou.
‘Yes, that’s the best way of putting it. Really that’s all anyone can say, isn’t it?’
‘Yeah,’ said Simou, and carried on working.
VI
‘When we get to the other side of the next door, it will all be new to me,’ said Dallas, as he waited for Cavor to climb aboard the perimeter car. Thirty minutes had passed since the two men had entered the R&R area, during which time they had more or less restored themselves with hot drinks and lots of calories.
‘It must have been at about this stage in the simulation that Rimmer walked through your hotel door with a gun in his hand. Or maybe even earlier. What I am sure of,’ added Dallas, ‘is that as soon as we left the R&R area and went through the first radial arc door, things went seriously wrong for us.’
‘You never said exactly what happened in there,’ said Cavor.
‘You’ve seen Gates’s hair,’ Dallas said. ‘My liver’s probably the same color.’
Cavor made no further mention of the incident except to observe that the main facility seemed eerie enough without the addition of any more tangible horrors.
‘Horror doesn’t even begin to cover what happened,’ said Dallas, and then he floored the accelerator. ‘But take my word for it, there are more than enough genuine ordeals that still lie ahead of us. Not least the labyrinth and the stealth robot that guards it. This place is the Mecca of adversity.’
A few minutes later the car pulled up in front of the airlock door that led out of the R&R area and into the section of the facility perimeter that was lacking an atmosphere. Once inside the airlock, both men switched on their life-support systems and awaited their exit, each with his own thoughts.
The silence persisted as long as it took for the electric car to travel through a semicircular section of the perimeter and arrive in the water purification and processing plant.
‘Are you sure we can pull this off, Dallas?’ Cavor’s question was prompted by a first sight of the exterior door of the nuclear reactor.
‘Nothing is ever certain where nuclear power is concerned,’ said Dallas. ‘Especially when you’re flirting with uranium neutrons. The nuke engineers make a calculation they call PRA. Probabilistic risk assessment. It’s a description of the safety of a nuclear plant in terms of the frequency and consequence of any possible accident and whether the engineering safeguards can prevent such an occurrence. Well, that’s what we have here, Cav. PRA. Thanks to Prevezer’s computer model we have a predicted operational safety window. The computerized TLDs[121] we’re wearing will tell us how many centigrays we’re absorbing and at what rate. They’ll also tell us where the lethal dose will lie.’
He stopped the car outside the reactor, and switched off the power.
‘However, I’m not sure we can pull this off, no. There’s a risk, but the probability of it proving lethal has been assessed.’
‘Why not just scram the reactor?’
‘It’s a good question,’ said Dallas. He stepped down from the car and approached the red light of the proximity detector, waiting for the door computer to scan the ID chip in his helmet. ‘As a matter of fact, a reactor shutdown is exactly what we must be careful to avoid. If we scram the reactor, the chain reaction will stop. If the chain reaction stops, the turbine will slow down. If the turbine slows down, then the electricity stops. And if the electricity stops, the vault door won’t open. So not only can we not scram the reactor as a deliberate choice, we’ve got to be careful not to do it accidentally. The containment room walls may not have security vibration detectors, but there are lots of sensitive instruments and operating mechanisms in there. We bump into anything, or jar something, and that could cause a scram by itself.’
The red light above the proximity reader turned green, and an electronic voice pronounced that they were clear to proceed on foot only. Cavor collected his gear and followed Dallas through the reactor room door.
The type of nuclear facility operating inside the First National Blood Bank was a graphite-moderated, gas-cooled reactor using a highly enriched fuel consisting of tiny pellets of uranium 235, each surrounded by the same kind of heat-resistant ceramic material that covered the nose of the Mariner. These ceramic shells provided the fuel with a miniature containment system: In the event of a total coolant loss, the temperature of the fuel would remain below the failure point of the ceramic coatings. A meltdown was, therefore, theoretically impossible. Removing heat from the reactor core was the job of the coolant, which in this case was helium gas. Although helium coolant was considered less capable than water of handling excess heat in an emergency, helium cannot boil and, unlike water, does not react chemically with other substances, thus avoiding the possibility of steam or hydrogen explosions; and also unlike water, helium exists in plentiful supply on the Moon. The use of water in this helium-cooled, graphite-moderated reactor was therefore limited to providing a steam source, being boiled by the reactor inside a steam generator to turn a turbine electricity generator. Water was provided in the shape of ice blocks from the huge ice field at South Pole-Aitken Basin,[122] from condensed steam, or from the recycled urine of First National security employees.
Dallas led the way into the reactor room, pointing out the turbine, the condenser, and the generator along the way.
‘It’s not as big as I’d expected,’ said Cavor.
‘It doesn’t have to be very big. It’s only a small reactor, about the same size as you’d get on an oceangoing warship. Powering this facility requires only a few hundred kilowatts.’ He drew Cavor’s attention to where pipes from the turbine and the condenser entered a heavy concrete wall and the massive steel door that was located between these.
‘That’s the containment room in there,’ he said. ‘The idea being to contain radioactivity in the event of an accident. Once we’re through that door we’ll be right alongside the reactor. The whole thing is controlled by the Descartes computer from inside the vault. The Altemann Übermaschine. Same kind as the one that runs Terotechnology back on Earth. Pretty damn good computer. About the most powerful there is.
‘Most of the time,’ Dallas continued, ‘exposure will be quite steady. But it is possible that the computer may adjust the power output of the reactor, and that’s where our problems will start. You see, controlling a reactor means limiting the number of neutrons from each fission that cause subsequent fissions to precisely one neutron per fission. It’s what the nuke engineers call the multiplication factor. You control the MF by the use of graphite control rods between the uranium fuel rods. If the MF goes above one, then you insert control rods to absorb more neutrons and reduce the MF.’
121
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