Small Modular Reactors Licensing Process Based on BEPU Approach: Status and Perspective
Round 1
Reviewer 1 Report
This work reviews the Best Estimate Plus Uncertainty (BEPU) approach and clarifies the possibility of using this approach in the licensing process of Small Modular Reactors (SMRs). The lack of experimental data and tight coupling of phenomena along with uncertainty quantification are the main challenges ahead of using BEPU in the licensing process of SMRs. SMR licensing is one of the most critical challenges in the front deployment of these reactors. This challenge stems from innovations in SMR designs and systems. Due to the lack of experimental data and technology knowledge, the licensing challenge for non-water coolant SMRs is more complicated. Almost all the previous generation reactor licenses were based on conservative analysis, while the decision-making methods based on the best-estimate and realistic approach have received more attention in recent years. Implementation of the BEPU approach in the licensing process is an open issue in several countries but the most of previous licensing was based on a conservative approach, thus, there are resistances to replacing the BEPU methodology as an efficient substitute licensing strategy for new construction reactors.
I have a suggestion which I think will improve the overall readability of the paper: to discuss in more detail the new results given in the paper. In my opinion more of the results and discussions in the manuscript are already presented in previous papers, so an accent of the new results shown in this paper will be helpful for the readers.
Summarizing. The article is well written and articulated. I appreciate the work done, presentation, and once the point raised above is addressed the manuscript can be accepted for publication in Sustainability.
Author Response
Dear Respected Reviewer,
The authors all truly appreciate your valuable comments and suggestion. The answers file has been attached and according to your comments, the required changes have been implemented in the revised manuscript.
Sincerely yours,
Dr. Reza Akbari
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Licensing based on BEPU is demanding because it requires the performance of a large number of calculations, as well as the prior definition of uncertain parameters, their distributions, and uncertainty intervals. How would this procedure be carried out in SMR licensing, where uncertainties are much greater than in older generations of NPPs where there is an extensive operating experience?
In abstract you mention that BEPU approach is selected for licensing in some cases. Do you know some examples of using BEPU in current legislation?
The values of key quantities, such as PCT or DNBR, can vary within wide intervals, after performing an uncertainty analysis, due to variation in input parameters or a lack of modelling accuracy of some physical phenomena occurring in SMRs. In that case, it can be realistically expected that some calculations will exceed the acceptance criteria. How the analysis is then carried out further to reduce uncertainties? Do you have any examples of uncertainty analysis for SMR that you could present in the paper?
Author Response
Dear Respected Reviewer,
The authors all truly appreciate your valuable comments and suggestion. The answers file has been attached and according to your comments, the required changes have been implemented in the revised manuscript.
Sincerely yours,
Dr. Reza Akbari
Author Response File: Author Response.pdf
Reviewer 3 Report
1 the chanllenges of MSR for the licencing process should be discussed in detail.
2 The advantage and disadvantages could be added.
Author Response
Dear Respected Reviewer,
The authors all truly appreciate your valuable comments and suggestion. The answers file has been attached and according to your comments, the required changes have been implemented in the revised manuscript.
Sincerely yours,
Dr. Reza Akbari
Author Response File: Author Response.pdf
Reviewer 4 Report
Ø The abstract focuses on the challenges and limitations of using BEPU approach for licensing SMRs, but there is a lack of experimental data, and tight coupling of phenomena poses significant challenges
Ø Resistance from developers and regulatory bodies to re-assess previous reactors using the BEPU approach. Potential solutions should be provided to overcome challenges or address resistance.
Ø No clear overview of the advantages/disadvantages of SMRs or how they compare to traditional nuclear reactors. The status discusses the licensing process of Nuclear Power Plants (NPPs) and the challenges faced in licensing Small Modular Reactors (SMRs), but it does not clearly state the research question or objective. Additionally, there is no clear structure or flow in perspective, making it difficult to follow the main argument.
Ø The perspective does not provide a critical analysis and only presents information without offering any insight or analysis which should be improved.
Ø The challenge and cost of implementing the BEPU methodology should be improved. The need for qualified computer codes and software, verification, and validation, and uncertainty quantification to achieve confidence in the safety assessments can be included
Ø The need for adequate scaling programs of SMR technologies should be included.
Ø Lack of discussion on potential drawbacks or limitations of using BEPU methodology in SMR licensing process. No specific information or data was provided on the degree of challenge related to licensing SMR technologies.
Ø detailed information on potential challenges and limitations of implementing the BEPU methodology for SMR licensing would improve the perspective.
Author Response
Dear Respected Reviewer,
The authors all truly appreciate your valuable comments and suggestion. The answers file has been attached and according to your comments, the required changes have been implemented in the revised manuscript.
Sincerely yours,
Dr. Reza Akbari
Author Response File: Author Response.pdf
