The Interplay between Breeding and Thermal Feedback in a Molten Chlorine Fast Reactor

Round 1

Reviewer 1 Report

Interesting paper. Actually, quite nice extension of the previous paper. Please consider, if repetition of the figures is necessary. 

Text "been demonstrated on a laboratory scale [8]" suggest that B. Merk has a laboratory and did the test of closed fuel cycle there. Please consider if reference is needed at all. If so, I would rather expect reference from 1946-1956. E.g. Zinn W. H., 1946, Design of fast neutron breeder test pile, Chicago. Univ. Metallurgical Lab, TID-10085.

At the same time, Pu recycling was more than proven by loading Russian BN reactors with MOX fuel. Nonetheless, the paper speaks only about enriched uranium. The relevance is thus indirect. Probably only initial fuel cycle is analyzed. 

As in the previous paper fuel composition evolution is not shown/considered to be important. Multiplication factor acts as a single criteria. 

The applied cross-section library is not specified in this paper.  

The idea, that temperature can be used to control the reactivity and even prolong the irradiation is interesting. It is actually used in some PWR already now to increase the burn-up. Consider a reference. The only technological issue will the the needed temperature range. Other reactivity control mechanisms can be cheaper than to extend the operating range to quite high temperatures.  

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors,

the manuscript aims at providing a basic neutronics study on the dynamic behavior of a model of a molten salt reactor.

Additional information/review are kindly required. Please, see below:

Lines 31-38

I guess that this is a ‘relict’ from the authors guideline, please update.

Lines 50-51

Why ‘However’? The above-mentioned projects (lines 47-48) also include feasibility studies of MRSs loaded with fuels with a significant amount of Minor Actinides aimed at close fuel cycle employment.

Table 1.

Please correct ‘b103’ to ‘b 10³’.

Lines 116-127

I guess that this is a ‘relict’ from the authors guideline, please update.

Chapter 3

Please, provide the initial vector of the heavy metal isotopes.

Line 142.

Please, provide a reference for the v7-252 cross section library.

Lines 151-156

Please, specify the reasons of such modelling. Does it come from the studies performed in the frame of the projects mentioned in Lines 47-48?

Lines 162-163

Up to this point of the manuscript, the aim of this parametric study is unclear. The goal of the paper is described in Lines 76-82. Nevertheless, it is not clearly stated how these ‘general’ goals are translated in the study. Namely, which physical parameters affected by the variation of the radius and of the fissile content one should look at?

Lines 173-174

Why the first guess thermal feedback is set to -6.5 pcm/K?

Lines 185-186

The meaning is kept, but the sentence is complicated. Please rephrase.

Table 3.

• Please correct ‘cm’ to ‘m’.
• How much is the uncertainty on the criticality values?

Lines 222-237

The precursors are assumed to be at the equilibrium, I guess.

Line 261-264

The behavior observed in Figure 6 is not specific of MSRs only, but of any system when a transient calculation is broken down into successive steady-state calculations.

Results in Figure 6 are also deeply affected by the change of the fuel composition during the burn-up. How much vary the feedback coefficients during the cycle?

Table 5.

• Please correct ‘cm’ to ‘m’.
• How much is the uncertainty on the criticality values?

Best Regards

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Dear Authors,

thanks for your clarifications and for your review.

Best Regards