Irradiation Characteristics of Non-Impregnated Micropore Graphite for Use in Molten Salt Nuclear Reactors

Round 1

Reviewer 1 Report

The manuscript is well written and presents interesting findings, however, I have major concerns about structure and way of presenting the results showing tendencies to subjectively overrating the produced materials.

p2-l72 missing space after dot

p2-l96 important information about the systhesis is not present

- information about the petroleum coke, binder are missing

- information about the dwell time at  2900 C 

p3-l116 reference to the SRIM sotware simulation is missing

p3-l198 How Hg penetration is relevant to molten salt penetration, please ad some reference, that such comparison is adecvate. Otherwise, please refere only to porosimetry 

My main concern lies in the comparison of NSPG and IG-110. In the conclusion, you claim you proved that NSPG is superior to IG-110 in radiation resistance. However, apart from SEM analyses, which are mentioned for both types of graphite, other analyses are poorly showing IG-110. Surface roughness (Fig5) dependence on dpa presented only for NSPG, XRD on dpa (Fig6) only for NSPG. Raman spectra (Fig 7) again only for NSPG, even though you write on p10 l343 that Fig 7f contains data for IG-110, which I cannot find.  

Therefore I cannot accept such strong arguments found in the conclusion about the comparison of both types of graphite. I recomend to add relevant data or reconsider structure of the article. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This study introduces the fabrication of non-impregnated small pore graphite (NSPG) for molten salt reactor applications and investigates the irradiation response of NSPG. This study is of interest of the nuclear community in the design and optimization of graphite components to be used in future reactors. The microstructure of NSPG before and after irradiation was examined by SEM, AFM, XRD and Raman spectra, which was compared with the IG-110 graphite. The results were analyzed and discussed in details, however, a couple of questions need to addressed.

1. Line 236 and line 273, “absorption of irradiation-induced swelling” is an inappropriate description. The shrinkage of the pores is due to mass transport from the matrix to the free surfaces of the pores. Swelling is the volume change due to irradiation damage, and it makes no sense to say that the swelling is absorbed.

2. Line 234, to argue the average size and density of pores have been reduced after irradiation, the authors need to provide the statistics of pore size and density evolution as a function of irradiation dose.

3. Define beta in the equation for calculating Lc.

4. The authors argued that the decrease of Lc was due to the strain accumulation and amorphization induced by irradiation. However, none of these arguments were supported with experiment evidence and were not rationalized with enough support from literature.

5.Oxidation of graphite is a major concern for the application of graphite components in reactor systems. Did the authors observe any surface oxidation in NSPG and IG-110 after irradiation?

6. Figure 1, “Surface”, not “Sueface”. In the caption, use “displacement per atom” to replace “displacement”

7. There are numerous improper and uncommon wordings and grammar mistakes in this manuscript. To name q few:

Line 50, … require time and cost consuming.

Line 71, … whether the irradiation resistant of the…

Line 258, …has a certain resistance…

Line 264-265, …and to quantitatively observed…

Additionally, it is better avoid writing very lengthy sentences, e.g. “These are caused by…, which…, which…, leading to…”. These sentences can be easily divided into several short sentences that are more concise and easy to read.

The authors need to polish the language and carefully proofread their manuscript.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Regarding the article "Irradiation characteristics of non-impregnated micropore graphite for use in molten salt nuclear reactors," the following questions are raised:

 

1.      What are the key technical challenges in the preparation process of NSPG?

2.      7 MeV Xe26+ ions are commonly used to simulate neutron radiation. Please cite relevant literature. Avoid clustering references, such as [13,14,16,18-20].

3.      "IG-110 has already been maturely applied in many reactors." Please provide additional references. Additionally, the density and open porosity of IG-110 measured were 1.77 g/cm3 and 18.4%, respectively. This should be compared with the literature.

4.      The abbreviations NPIG and SSNG should be accompanied by their full names when first mentioned, such as Nanopore-isotropic graphite (NPIG).

5.      The term "Sueface dose" indicated in Figure 1 should be corrected to "surface dose."

6.      How was the uniformity of pore size in the NSPG prepared by the authors ensured?

7.  How do the porosity and microstructure of graphite materials affect their performance? Additional literature can be included to support the explanation.

8.      How does the structural stability of NSPG differ under higher dose radiation or prolonged radiation exposure?

9.      Apart from reducing porosity, what other methods can be used to further enhance the radiation resistance of graphite?

 

10.  The authors should list other materials and compare their abilities in radiation resistance.

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Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The revised manuscript can be accepted for publication.

The authors have adequately addressed my previous comments.

Reviewer 3 Report

The article has been improved to a satisfactory level. Therefore, I can recommend publication in the present form.

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