Status of Scoping Nuclear Analyses for the Evolving Design of ITER TBM Port Cells

Round 1

Reviewer 1 Report

The paper addresses a very important nuclear calculation regarding the ITER TBM program. Is well presented but it needs some revision before publication. All the comments are reported in the file attached.

Comments for author File: Comments.pdf

Author Response

The authors would like to extend their gratitude for the time and effort the reviewer has put in reviewing the manuscript. Below is a point-by-point reply:

• Comment 1: The word artificial was initially used to signify that the configuration with the TBM-PP with two dummies and the PF is indeed an artificial one. This is due to the fact that the PF will be present only with the actual TBMs in the PP. The TBM-PP with dummies is intended to provide the same shielding functionality as the original TBMs in case of its absence, due to delays in procurements or any other unforeseen causes. Since both the TBM-PP with dummies and with the original WCLL/HCBP will provide the same shielding performance, it was possible to use it to perform analyses in support of the PF and BP designs, which is the main purpose of the analysis presented in the paper. This is mentioned in section 2.3, line 177.
• Comment 2: definition is added.
• Comment 3: The authors prefer to keep the two paragraphs as is. In nuclear analysis of fusion facilities, preparation of the radiation transport model is an integral part of the analysis itself. It is often the case that different workflows are used, and that is the main reason the authors included those two paragraphs to give a glimpse on how the neutronics model was prepared from CAD. Also, this is the latest updates on the PF/BP design and a new final design phase is to start in the future, so the authors do not currently intend on publishing an additional article on this analysis and it would be beneficial to have all possible information on the model/analysis in a single paper.
• Comment 4: the subfigures were enlarged for a better visibility/readability.
• Comment 5: This is an internal ITER document. "IO" was added before the word "nuclear" to highlight that the standards are IO's.
• Comment 6: the word "artificial" is removed to alleviate any confusion.
• Comment 7: LiPb exists only in the PF! The TBM-PP has two dummies which provide the same shielding as the TBM-PP with the original sets. Hence, the TBM-PP with dummies was used to perform analyses that target assessing the impact of the evolution of the PF and BP designs. This was decided to be consistent with previous analyses on the IO side. LiPb is not present in the TBM-PP with dummies but since on the radiation transport that would be similar to the one with the original sets, it was possible to have such configuration and focus on the radiation transport results in the PI; namely the PF and BP.
• Comment 8: position highlighted on figure 6a.
• Comment 9: No necessary since it has been already implemented in figure 6a. Figure 6a, 7a&b are complementary to 6a.
• Comment 10: the word "density" is removed since the unit of the activity will suffice to convey it is indeed the activity density.
• Comment 11: It is indeed an important parameter. IO provided the parameter value based on internal documents of previous analyses. The document is not disclosed by IO as part of the analysis described in this paper, but the needed input was provided by IO. As a result, the most suitable form to report a reference for this is as personal communication, since any other form of referencing won't be accessible to the reader!
• Comment 12: figure has been enlarged.
• Comment 13: The following sentence was added, "It is imperative to keep in mind that the approximation to the LiPb contribution - to the SDDR in the PI - introduced below is just for scoping and doesn't necessarily reflect the final calculation of the SDDR contribution from residal LiPb in the PF. As a result, no safety or maintenance scheduling should be based off these estimations." As for the uncertainty, the comment is not clear since the uncertainty in the SDDR is already reported in the table!
• Comment 14: Same as in the 17th reference! The input was provided by IO and was used to perform the nuclear analysis. The internal documents describing the references are internal to IO and were not part of the data exchanged in connection to the nuclear analysis contract with KIT.

Reviewer 2 Report

The manuscript is interesting and clear. The nuclear analysis is described in a way rather comprehensive. The results are also in line with a similar analysis carried out for the EU TBM Program, where the WCLL and HCPB-TBM sets have been considered. However there are two small points:

1. many of the radiation map figures are very difficult to be read. They should be enlarged, if possible;

2. in the Conclusion, there is a typo in the neutron flux (row 503) that needs to be fixed.  

Author Response

The authors would like to extend their gratitude for your valuable time and efforts in reviewing the manuscript. Below is a point by point reply:

1- All figure have been enlarged. 

2- The typo has been fixed.

Thank you

Round 2

Reviewer 1 Report

The reviewer acknowledges and thanks the author for the great effort in reviewing the paper which is now more clear and readable. I understood all explanations in the answers to original comments. Only one point to clarify before publication related to the comment #13 which was probably not clear.

Paragraph 5.3 related to “Residual Activated LiPb Source” is now clearer to the reader. Anyway, the uncertainties reported in the table 4. (2^nd raw) is not the uncertainty related to the procedure used to define the new level of SDDR due to LiPb residual layer but it is indicated as the MCNP relative error which is not the same.

Could the author roughly quantify the uncertainties related to the approximated procedure used for this evaluation?

Author Response

Thanks to the reviewer for clarifying the comment on the uncertainties in table 4. The uncertainties in the activated column is the one reported by MCNP from the SDDR calculation step - photon transport. On the second row, while the previously calculated SDDR due to LiPb was indeed that reported by MCNP, in this paper we used an approximation to estimate the contribution in the new model. As a result. the uncertainties were calculated for that approximated contribution. However, the uncertainties is so low that they appear identical in the second row. This is manily due to the nature of the distributed source along the LiPb pipe which resulted in low uncertainty for the SDDR over the mesh covering the equatorial port. The uncertainty of the sum is calculated based on the previously mentioned uncertainties. The word (Calculated Relative Error) could be replaced with (MCNP Relative Error) to highlight that it is an estimated uncertainty and not the one reported by MCNP.