Shipyard productivity, shipyard quality

To supply the electricity that the emerging economies so desperately need, we will require 100 one GWe ThorCons per year for the foreseeable future. And we need them soon. We need a system for producing fission power plants, not individual fortresses. Fortunately such a system exists. It’s called a shipyard.

ThorCon’s genesis is in ship production. The Hellespont Fairfax is one of eight ships built by ThorCon’s predecessor company. This ship is the largest double hull tanker ever built. She can carry 440,000 tons of oil. Her steel weight is 67,000 tons. She required 700,000 man-hours of direct labor, a little more than 10 man-hours per ton of ship steel. About 40% of this was expended on hull steel; the rest on outfitting. She was built in less than 12 months and cost 89 million dollars in 2002.

A good shipyard needs about 5 man-hours to cut, weld, coat, and erect a ton of hull steel. The yards achieve this remarkable productivity by block construction. Sub-assemblies are produced on a panel line, and combined into fully coated blocks with piping, wiring, HVAC (and scaffolding if required) pre-installed. In the last step, the blocks, weighing as much as 600 tons, are dropped into place in an immense building dock.

Block construction is not just about productivity. It’s about quality. Very tight dimensional control is automatically enforced. Extensive inspection and testing at the sub-assembly and block level is an essential part of the yard system. Inspection at the block level can be thorough and efficient. Defects are caught early and can be corrected far more easily than after erection. In most cases, they will have no impact on the overall project schedule.

Daewoo Shipbuilding & Marine Engineering shipyard

ThorCon is designed to bring shipyard quality and productivity to fission power. But ThorCon’s structure is simpler and much more repetitive than a ship’s. The fission island employs steel plate, sandwich walls filled with concrete or sand. This results in a strong, air-tight, ductile building, all simple flat plate. A properly implemented panel line will be able to produce these blocks using less than 2 man-hours per ton of steel.

The complete ThorCon power plant will be towed to its installation site.

Small is beautiful

Fissile fuel has a million times more energy than fossil fuel. Not only does this mean that fuel requirements (and waste) for a big power plant are measured in kilograms per day rather than thousands of tons per day; but it also means that, if you operate at low pressure, the plants can be small. The ThorCon reactor operates at near ambient pressure. ThorCon does not need much space. Nor does it consume a lot of resources. In fact, ThorCon is so small that the fission island almost fits into two center tanks of the Hellespont Fairfax, and requires one-fourth as much steel.

The steel weight of a 500 MW ThorCon is about 50,000 tons. The world’s largest shipyard can build more than 2,000,000 steel tons of ships per year. A single shipyard can produce 20 GW’s of ThorConIsle power per year. In terms of resource requirements, one gigawatt of ThorCon power is not a big deal. The scale up rate will not be limited by shipyard capacity, but by the rate at which the turbogenerators can be built.

If it breaks, send it back

In the ThorCon system, no complex repairs are attempted on site. Everything in the fission island except the hull itself is replaceable with little or no interruption in power output. Rather than attempt to build components that last 40 or more years in an extremely harsh environment with nil maintenance, ThorCon is designed to have all key parts regularly replaced.

Up to 50 ThorCon plants are supported by a Centralized Recycling Facility (CRF) and a separate Fuel Handling Facility (FHF). Normally, the Cans are changed out every four years. When the Cans need replacing, they are shipped to the CRF in a special purpose Canship. The video above shows a Can being transferred to the Canship. At the CRF, the Cans are disassembled, cleaned, inspected, and worn parts replaced. The problems of decontamination and waste disposal are shifted from the plant to this facility.

This system of regular replacement of the most critical components means that major upgrades can be accomplished without significantly disrupting power generation. And since the returned Cans are disassembled and fully inspected, incipient problems will be caught before they can turn into casualties.

Such renewable plants can operate indefinitely; but if a ThorCon is decommissioned the process is little more than pulling out but not replacing all the replaceable parts.