Research on the Influence of Negative KERMA Factors on the Power Distribution of a Lead-Cooled Fast Reactor

Round 1

Reviewer 1 Report

Overall, I think the discussion of differences in KERMA data leading to differences in reactor heating calcualtions is a very interesting topic.  However, I think there are changes that need to be made.

The biggest thing missing from this paper is a detailed discussion of why you do not expect negative KERMAs.  In reality, negative KERMAs are a real effect in systems at elevated temperature, although NJOY cannot produce data for this case.  For what is in the paper, KERMA should not be negative, true -- but this needs to be better explained to the reader.  For instance, you could discuss that KERMA is the sum of kinetic energy of each charged output product, and the sum of positive quantities cannot be negative.

Next, the results shown aren't directly related to negative KERMAs.  Running MCNP doesn't allow these negative KERMAs, so you are showing the results of differences between ENDF and CENDL calculated KERMAs.  They could be all positive, and there would still be differences.  Other than positivity, there's almost no discussion of why the CENDL data is preferred.  If it's indeed photon production in MF12-15, then show the data and make an argument to support it.

You several times mention deficiencies in NJOY processing, but the negative KERMAs you point to are not a deficiency of NJOY but a result of unbalanced data in ENDF.  You should suggest that ENDF be improved.  If you know of deficiencies in NJOY, those should be fully explained.

Finally, substituting CENDL data for ENDF data could influence reactor heating calculations for reasons other than KERMA data, as the rest of the evaluations are different.  You could do something like substituting only the photon data into the file and make the same comparison, which would make it much cleaner.

For presumably non-native English speakers, the quality of the English is strong in this paper.  There are a few unnatural sounding sentences, but the points are all clearly made, and nothing is problematic.  Thank you for the attention to detail.

Author Response

Dear reviewers and editor,
        The detail reply can be found in the attached file. Some equations can not view in the txt reply. 

Thanks very much.

Xubo Ma

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper tackles important problem in numerical modelling of energy deposition by neutrons and photons in nuclear systems. The additional explanations and improvements are necessary:

32 – Please explain the term „reactor economy”

58 – What defect of NJOY code? Please explain.

64 – What does the authors understand under “and so on”. Please explain.

85 – 68 – The sentences is not clear. Please reformulate.

128 – What elements exactly contain Moa nd Nb? Please explain in the paper

146 – What is the error or std of Keff and tallies?

164 – MW thermal or electrical. Please explain.

181 – What normalisation issue? Please explain.

Fig.6 – Please provide reference dimensions.

General comments:

Please add at the literature level more information about lead cooled fast reactor, e.g. on Monte Carlo modeling of Lead-Cooled Fast Reactor in adiabatic equilibrium state.

At the end of “Introduction” the section with brief introduction of other sections content should be provided.

Please explain all used abbreviations.

Please explain in more details RBEC-M benchmark.

The power distribution depends on many factors also on detection of numerical power shift anomalies in burnup modelling, which should be referred and referenced in the paper.

Moderate editing of English language required

Author Response

Dear reviewers and editor,
     Detail reply can be found in the attached file, some figures and equations can not be viewed. 

Best regards.

Xubo Ma

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thank you for your responses and your changes to this manuscript.  This is indeed a very interesting study, and it is a good reminder for the ENDF and data processing community to pay attention to KERMA.

I still don't like some of the discussion surrounding "negative" versus "different" KERMA values between the libraries.  The negative values are egregious problems, but there are lots of ways for KERMA to be unphysical without being negative -- and I think unphysical KERMA is the true purpose of your study.

That said, highlighting which nuclides lead to negative values, which must be incorrect in your study, is valuable feedback for the community.  And showing the effect of replacing them is also valuable.  So rather than continue to debate about some of the details of the language used, I think I can recommend this manuscript for publication.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The point was not adequately adressed. The concept of adiabatic equlibrium was not mentioned n the paper, please improve.  Please add at the literature level more information about lead cooled fast reactor operating in adiabatic equlibrium, e.g. on Monte Carlo modeling of Lead-Cooled Fast Reactor in adiabatic equilibrium state (https://doi.org/10.1016/j.nucengdes.2016.02.025). 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf