1 January 2002

The first paragraph of our article stated that the proposed approach will be practised under risk informed performance based (RIPB) regulation defined by RG1.174-RG1.178, which are available on the NRC website. These regulations are the presumptions and foundation of this article and our research project.

RG1.174 prescribes the required procedure and information needed for applying for changing the original licensing commitments, which include detailed impact analysis, rationale, accuracy, uncertainty, sensitivity, and so on. Moreover, all information has to be open to the public for comments. The concerns raised by Professor Bloomfield et al are addressed by RG1.174 regulations and also specified in the last paragraph of our article as issues needed to be solved. In other words, if the issues that concern the Professors cannot be solved, RIPB approach will not be used.

Our article was abridged from two of our previous technical reports:

The Applicability of Applying RIPB to Digital I&C Regulation.

A Bayesian Approach for Applying RIPB to Digital I&C QA Programmes

Readers who are interested in the above reports may e-mail the author ( for a copy of these reports.

  We understand that the application of PRA, especially the expert opinion part, has always been controversial. This is why RG1.174 set up rigourous criteria for applying risk informed practice, and it even requires all information open to the public for comments. We consider these requirements important and necessary to ensure the safety of nuclear power plants, and thus criticisms are highly appreciated.

There are indeed errors in the printed BBN figure (nodes in central upper part with names: analysis financial pressure and analysis schedule pressure). The errors were made during the re-drawing process by NEI staff since the original figure we submitted could not be printed directly. It really demonstrates how error-prone and difficult BBN technique may be, as pointed out by the Professors' comment. The correct figure can be found in our technical report. We apologise for the mistake and thank you for the correction.

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