Shipyard Production of Nuclear Power Plants

There had been an immense amount of hype, and considerable nonsense written about Small Modular Reactors. When you are trying to solve a problem as big as the Gordian knot, the closely coupled issues of electricity poverty and planet heating, small is not beautiful. There are strong economies of scale in nuclear power generation. Any solution that does not recognize this will be hopelessly wasteful. But it is also true that we must take advantage of the order of magnitude improvement in productivity and quality associated with assembly line manufacture, as compared to conventional on site construction. What we need are Big Modular Reactors, the biggest reactors we can build on an assembly line.

The masters of building big on an assembly line are the shipyards. World class commercial shipyards, exposed to a brutally competitive market, have developed truly remarkable productivity. I spent three years in Korea watching this magic. Flat plate comes in at one end of the property and an immense, complex ship goes out the other end. A good yard needs only 400,000 man-hours to build a ship weighing 30,000 tons, a little more than 10 man-hours per ton. This includes everything: coating, piping, wiring, machinery, and testing. The contract is fixed price, which will be about $3000 per ton. The ship will be built in less than a year. The ship must perform per contract and there are substantial penalties for late delivery.

The shipyards achieve their remarkable productivity by a combination of automation and block construction. Sub-assemblies are produced on a automated panel line, combined into assemblies, and then into fully coated blocks with HVAC, piping, wiring (and scaffolding if required) pre-installed. In the last step, super blocks, weighing as much as 3000 tons, are dropped into place in a building dock.

Figure 1. One man controlling 48 welding machines

Block construction not only creates order of magnitude improvements in productivity; but it also produces striking improvements in quality. Very tight dimensional control is automatically enforced. The blocks are 30 m cubes with an overall tolerance of +/-5 mm. Westinghouse targeted +/-15mm on their far tinier AP1000 modules, and did not maintain this, in some cases, not even close.

Figure 2. Two super blocks in building dock

Extensive inspection and testing at the sub-assembly, assembly, and block levels is an essential part of the yard's productivity. Inspection at these levels is easy. Defects and faults are caught early and can be corrected far more easily than after erection.

For this to work, detailed design and production scheduling must be tightly integrated. All the world class yards do their own engineering. The process is divided into basic design and detailed design. Basic design takes a potential project far enough to do accurate costing, allow the yard to bid the job, and be confident that it has a good handle on the resources required. After they sign a contract, detailed design takes over. Detailed design not only does the working drawings, but just as important the production scheduling down to per shift detail. This includes scheduling each sub-block and block lift by crane. The weight and center of gravity of each lift is calculated and the lifting lugs are part of the design. Even any scaffolding which will be required in final erection is part of each block design, and installed at the block level. Detailed design and production scheduling cannot be separated.

The production process is so tightly scheduled that any delay cascades throughout the yard. A problem on one project is a problem for every project in the yard. To prevent these delays, the yards have a well developed Test and Inspection System. The yards' Quality Standards are 200 page books covering just about every imaginable defect. A steel sample is taken of every ladle. Plates are marked by date and ladle. Tests are much easier to do and to automate at the sub-assembly and block level then after erection. Every fillet weld is pressure tested at the block stage. Critical welds are either xrayed or tested ultrasonically.

The whole process is overseen by an independent inspection and certification outfit, known as a Classification Society. The Classification Society approves every drawing, and Classification Society inspectors witness and sign off on every scheduled test. The cost of this service is about 2% of the ship's price. Classification Society approval is required for the shipowner to purchase insurance.

A third layer is the buyer's own inspectors. The shipowner will have a team of his own people in the yard, witnessing and signing off on every test, constantly patrolling and ensuring the contract standards are upheld.

The overall result is the ships are almost always delivered on time and perform as designed. We need to build nuclear power plants like the world class shipyards build ships.

But the shipyards are petrified of nuclear. A key to the efficiency of this whole process is that all the players understand and agree to the rules of the game. Once the contract is signed, all the quality standards, all the test protocols, everything is known and fixed. Tests are scheduled when the yard wants to do the test. The Classification Society and the owner's inspectors need only be given proper notification. If they don't show up for the test, the test is deemed approved.

The current US nuclear regulatory system is just the opposite. There are no rules. This was demonstrated in early 2022, when two of the three NRC commissioners voted to rescind the licence extensions that a year earlier had been granted to the Turkey Point and Peach Bottom plants, after an 18 month review which cost the applicants millions of dollars. The two non-elected men, neither of whom had any background in energy, decided that the word initial in the NRC regulations did not mean initial. No sentient investor can allow himself to be exposed to such an inconsistent, arbitrary regime.

The yard system is based on functional tests. How the yard produces the product is the yard's business. The only thing that counts is the result. Test the weld; not the welder. If they allow nuclear style regulation into the yard, the shipyards know their finely tuned production process will be thrown into complete disarray. The yards cannot afford to have NRC-like bureaucrats telling them how to do things.

The nuclear regulatory system grew out of the way the US Navy builds ships. The shipyards that build Navy ships have access to exactly the same production technology as the Korean and Japanese yards. In fact, if you go into the US Naval yards, you will see the same equipment. But the results are completely different. Even a very lightly armed, non-combatant Navy ship will cost the taxpayers well in excess of $60,000 per ton. For comparison, a 600 MWe super-critical steam turbine and generator weighs about 1200 tons. It costs 100 million or $80,000 per ton and it is ALL high precision machinery. A ship --- Navy or otherwise --- like a nuclear plant is mostly simple steel.

Moreover, Navy ships are almost never delivered on time or anywhere close. Cost overruns of a factor of two or more are commonplace. And ``despite" elaborate quality assurance requirements and procedures, they almost never perform per original spec. In many cases, their performance is a tragic joke.

I have seen both sides of this coin. I spent the first 15 years of my career working for the U.S. Navy and the next 30 years in foreign flag tankers. So when I come to nuclear power plants, the question is not: can we build them in a shipyard? The answer is obviously yes. But the real question is: what manner of shipyard?

1) Will we build nuclear power plants the way the Koreans build ships?

2) Or will we build nuclear power plants the way the US Navy builds ships?

Will it be the certificate shuffling, ass covering, talent stifling, paperwork obsessed operation that Naval ship construction is or will it be competitive market enforced efficiency and quality? In America, even the most casual observer of US nuclear knows the answer to this question. Unless this changes completely, building a nuclear power plant in a shipyard will be no better than building it stick by stick in a swamp.