A pre-construction design review of the Hitachi-GE ABWR in the UK has proceeded to the next phase. Following a preliminary phase that ended in January 2014, the reactor design completed an initial technical assessment in August. But there remains lots more work to do before final approval, tentatively scheduled for December 2017.
"At the end of our Step 2 assessments we have not identified any fundamental safety or security issues that might prevent issue of a DAC or that would need to be addressed in order to acquire one," wrote the UK regulator, the Office for Nuclear Regulation. The reactor is also being reviewed by the UK Environment Agency, which said it has not found any ‘obviously unacceptable’ issues so far.
The next step of the process is a year-long analysis of the design at the systems level and primarily focuses on the safety arguments. The final step is the detailed assessment phase and focuses on the evidence provided by Hitachi-GE in the safety analysis, on a sampling basis, and typically takes around 28 months.
Despite the positive assessment, several technical issues did come up during the step 2 review.
First was an issue about common-cause failure in the reactor’s instrumentation and control systems, an issue that has also affected the UK EPR and Westinghouse AP1000 designs that have previously passed through the process.
Second, ONR has raised concerns about Hitachi-GE’s probabilistic safety assessment work for the reactor design. "At this point ONR do not have sufficient information to properly understand the risk profile for the UK ABWR, as this requires a full scope, modern standards PSA." As a result, ONR said that it would request Hitachi-GE to develop a detailed PSA programme and submit the PSA models, data, supporting analysis and accompanying documentation throughout Steps 3 and 4.
The Hitachi Horizon programme proposes building at least two circa 1300 MW plants at each of Horizon’s sites at Wylfa, Anglesey, and Oldbury, Gloucestershire, with the first unit becoming operational in the first half of 2020s.
