Office for Nuclear Regulation & Environment Agency

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Advanced Passive 1000 - AP1000®

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

Designer (requesting party): Westinghouse

Current positon: Assessment re-started in August 2014 following a pause. Westinghouse are now in the process of resolving outstanding issues before design acceptance can be granted.


  • 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

Make a comment about the AP1000 design

You can make a comment about the AP1000 design via Westinghouse's website. Westinghouse will respond to the comments and issues raised.

Find out the process

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

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 are two regulatory issues published for the AP1000.

More on issues

GDA issues

GDA issues remain following issue of interim design acceptance. They need to be resolved before a final design acceptance can be granted. There are currently 51 outstanding issues for the AP1000 and Westinghouse has published resolution plans for each issue.

More on GDA issues

Interim design acceptance

In December 2011, ONR and the Environment Agency granted interim design acceptance to the AP1000 design.

More on iDAC/iSoDA