Office for Nuclear Regulation & Environment Agency

Advanced Passive 1000 - AP1000®

©Westinghouse Electric Company LLC.  All rights reserved.  Used with permission.

Designer (requesting party): Westinghouse

Current positon: Assessment of reactor design complete. Design Acceptance Confirmation issued in March 2017. NuGen preparing to apply for a nuclear site licence to build and operate three AP1000 reactors at Moorside in Cumbria.


  • Apr-Sep 2007 - Step 1 (preparatory step)
  • Sep 2007 - Jun 2008 - Step 2 (initial assessment)
  • Jun 2008 - Dec 2009 - Step 3 (detailed assessment)
  • Jan 2010 - Dec 2011 - Step 4 (detailed design, safety case and security evidence assessment)
  • Dec 2011 - Westinghouse paused GDA activities with 51 outstanding issues remaining
  • Aug 2014 - Westinghouse recommenced GDA of the AP1000
  • March 2017 - DAC/SoDA Issue

Summary of the GDA issue close-out assessment of the AP1000© Reactor

Regulatory Issues and Resolution Plans

A regulatory issue is a serious regulatory shortfall identified by the regulators. The issues are potentially significant enough to prevent provision of design acceptance. There were two regulatory issues published for the AP1000®.

More on issues

Progress reports

At the end of each step of the assessment, the regulators publish detailed technical reports and a summary report.

Find out more about progress reports

GDA issues

There were 51 GDA Issues raised following the Interim Design Acceptance (iDAC) in 2011. For each of these issues Westinghouse published resolution plans to outline how the intended to address the issue.

More on GDA issues

Design acceptance

In March 2017, ONR and the Environment Agency the AP1000© design a Design Acceptance Confirmation and Statement of Design Acceptability.

More on DAC/SoDA