AP1000 – the Westinghouse Entry

“You can be sure if it’s Westinghouse”

The old advertising slogan from the 1950’s still contains a grain of truth. However, the Westinghouse of today is very different from the old company with several changes of ownership over the intervening years. At the moment the majority shareholder of Westinghouse Nuclear is Toshiba who purchased it from British Nuclear Fuels in 2006 who had purchased it from CBS in 1996 and so on.

Nevertheless, Westinghouse in its various incarnations can claim to have designed or built about half of the world’s nuclear power plants including many now operating in the US, France and Japan, an impressive record.

The AP1000 is a pressurized water reactor (PWR) moderated and cooled by light (normal) water using enriched uranium fuel.  It belongs in the same class of reactors as the AREVA EPR but with a net electrical power of 1100MW compared to 1600 MW of the EPR.

Personally, I find a lot to like in the design philosophy of the AP1000. The designers to the extent possible use components already tested and operating in existing reactors. In addition to having established suppliers, this also facilitates experience-based prediction of the operational characteristics of these components, information critical for convincing Probabilistic Risk Assessment of system safety. This key factor accounts for the AP1000 design being so far along in the US and European licensing processes.

Another design emphasis is on making the reactor simpler that its predecessors. For example, the AP1000 claims to use 50% fewer safety-related values, 89% less piping, and 85% less cabling.  That appeals to me on the grounds that the fewer components there are, the less there are to go wrong. Both Maintenance and construction should be easier.  

The AP1000 incorporates several “passive safety” features meaning that the reactor can make use convection and other natural phenomena to deal with accident scenarios. This used to be called “inherent safety” but this expression to my mind in the same class as “unsinkable ship” has thankfully passed into history as has the Titanic.

As noted elsewhere on this blog, Westinghouse has concluded a deal for two AP1000 reactors for South Carolina. Construction in China on the first AP1000 started in February this year. It is being constructed by a Chinese utility using technology transferred from Westinghouse and is expected to go into operation in 2013. This is an impressive schedule and it remains to be seen if the reactor can be built on time and on budget.

There was a rumour around a few months ago that Westinghouse was less interested than it might be in the Canadian market because it wished to concentrate on the US market. The forgings shortage and the fact that they were the only reactor vendor to show up at the Polish Engineers in Canada session in spite of the Ontario government gag order have been mentioned in support of this speculation.  I hope the rumour is false because from what I know at this point the AP1000 looks to be an excellent reactor.

Posted in AP1000. 1 Comment »

One Response to “AP1000 – the Westinghouse Entry”

  1. Don Jones Says:

    Re AP 1000 – the Westinghouse entry

    The AP1000 was developed from the Westinghouse reactors now operating in the U.S. These in turn were developed from submarine reactors that Westinghouse built for the U.S. navy, starting with the USS Nautilus, launched in 1954. The last order, in 1979, was the 1,188 MWe (net) Sizewell B unit in the UK which was based on the generic Standardized Nuclear Power Plant System (SNUPPS) design used for the Wolf Creek and Callaway plants in the U.S. The AP1000 makes more use of passive safety features than Westinghouse’s previous plants which depended on engineered safety systems.

    Prior to China ordering four AP1000 reactors, Westinghouse had no reactor orders since Sizewell B, in the UK, was ordered in 1979. The AP1000 has new passive safety features that are a major departure from the earlier proven designs of the 1970s. Westinghouse claim a 36 month construction schedule from first concrete pour to fuel load but this is based on computer simulation not on recent build experience like Team CANDU has had with the CANDU 6, the reference plant for the ACR-1000. Engineering, procurement and construction contracts for two plants, each with two AP1000 units, have been signed in the U.S., but no commitment to build.

    The AP1000 had design certification in the U.S. in 2006 but Westinghouse submitted an application in 2007 May to amend the certified design due to design changes. The regulator is currently reviewing this application. Anyway, design certification in the U.S. does not mean automatic, or even easier, licensing in Canada. The Canadian nuclear regulator does not have much experience with LWR technology so licensing would take longer than licensing an ACR-1000.

    While the EPR is an N4 with more engineered safety the AP 1000 safety design started from scratch to incorporate (untried) passive safety features. We should all thank China for being the first to take the risk in building the four FOAK AP1000s. The US government provided substantial financial aid to Westinghouse’s bid in China.


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