On the Possibility of Forming a Corium Pool by Induction Heating in a Melt Trap of the Lava-B Facility

Round 1

Reviewer 1 Report

The topic is interesting and falls within the scope of the journal. However, the underlying physics behind the experimental outcome is not described properly by the authors. The graphs need to be described thoroughly.

Hence, I recommend a major revision. 

Author Response

In the new version of the article, the introduction has been significantly revised, computer modeling is described in detail, and graphics are described in more detail.

Author Response File: Author Response.docx

Reviewer 2 Report

This paper discusses the possibility of forming a corium pool by induction heating in a melt trap. The computational results and experimental results presented are valuable but some flaws need to be improved as follows:

1.      The computational model developed in this paper is a two-dimensional axisymmetric model, so how does the author consider the influence of zirconium rods and steel rods shown in Figure 2 on induction heating? Please give a further illustration.

2.      In section 2, the computer simulation results show that the metal component melt forms approximately 60 minutes, please supplement the temperature field results at 60 minutes.

3.      Figure 3(a), the corium average temperature curve gradually becomes flat at 35 minutes, it seems that the melt has been formed at this time. Please give a further explanation of the temperature curve change.

4.      The results of the total integral amount of the heat between computation and experiment are very different, the computational model greatly underestimates the energy loss during the induction heating. Please give a further illustration of the difference.

5.      In Figure 4, the temperature measured by thermocouple 1-08 has an insignificant change. The temperature measured by thermocouple 2-02, which is at the same level as thermocouple 1-08, has a great change. The phenomenon needs further explanation.

Author Response

1. The heat release in the melt was set depending on the features of induction heating: the surface effect of penetration deep into the materials of the electromagnetic field of the inductor or the skin effect (in this calculation, 70% of the total heat was released on the surface layer). The depth of this surface layer is determined by the theory of induction facilities.

The prototype of the corium is a mixture consisting of several components. Taking into account the complexity of induction heating, it is not possible to fully take into account its effect on each of the charge components when conducting computer simulations. In this regard, a significant simplification is made. The trap load or the future corium is presented as a single-structured material.

Validation of the described method of modeling residual modeling in the corium prototype was carried out earlier and, therefore, it can be applied to conduct a non-stationary calculation of temperature changes in the elements of the trap.

In the article we have rewritten the text for a better understanding of this aspect

2. Yes, indeed. The graph shows that by 60 minutes the metal zirconium in the trap melts. You asked to add the temperature field of the trap at 60 minutes, but the purpose of the calculation and experiment was not only to obtain the melt, but also to heat it up to 2500 K. As the calculation shows, this happens by the 75th minute. In this regard, in the article we added an illustration of the temperature field of the model at a time of 75 minutes, not 60 minutes.
3. Yes you are right. The article gave additional explanations.
4. The difference between the experimental and calculated values of the total integral amount of the heat is 2%. We consider this to be a negligible difference given the uncertainty in induction heating. The fact is that determining the amount of energy introduced into the melt is a rather difficult task due to the large dependence of induction heating on the properties of the heated elements. In general, we agree that the model underestimates the heat loss, however, the simulations were carried out to approximate the time required to achieve the set goals with the specified characteristics of the inductor.
5. This is our carelessness. The fact is that thermocouple 1-08 failed during the experiment. it is better to remove its values from the graph, however, when describing the trap in Figure 3, it is marked. In this regard, the reader may have questions. Therefore, in the article we noted that the thermocouple was destroyed during the experiment.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors are presenting experimental facility and numerical modeling of heat transfer in this facility. The material is enough interesting for the specialists, which are planning to use the experiment measurements for the code validation.

 Please check the English language.

Questions (regarding ambiguities in the text):

1.    Regarding Figure 2 in the explanations the links 5 and 8 are showing the same structure. Probably the link 8 (UO2 tablets) should be deleted

2.      What does it mean “temp 100 V/min”?

3.      The abbreviations PMF and CSD are not explained

4.      Regarding Figure 3b – what power profile is assumed in the calculations?

5.      The Figure 4 is not clear: many curves are shown and I couldn't find which curve represents the power; the display of some curves is interrupted – probably the thermo-couples are destroyed at such moment?

6.      Regarding the “heat loss by the radiation from the surface of the charge/corium” – are the authors thinking to reduce heat loses from the top? 

 

Author Response

1. We agree that links 5 and 8 show the same structure. This is our mistake. However, in our opinion, link 8 should not be deleted because it shows the location of UO2 tablets in the trap. We made the appropriate changes in the article.
2. “temp 100 V/min” means that the working power of the inductor is achieved gradually as a result of increasing the voltage of the inductor by 100 per minute. In the article we have rewritten the text for a better understanding of this aspect
3. These abbreviations are an incorrect translation of the word Frequency changer". The article has been corrected accordingly
4. The power profile is assumed in the calculations according to the technical capabilities of the Lava-B installation. The heating power is 120 kW with an efficiency equal to 45%. A detailed description is provided in the section "the research methodology"
5. Red curve represents the power. yes, the display of some curves is interrupted due to their destroying.
6. The proposed method, as the study showed, can be implemented. However, there are a number of problems, including heat loss by radiation from the surface, which do not allow this method to be fully implemented. Reducing heat loss from the surface can significantly improve the efficiency of obtaining a corium prototype in a trap, reduce heating time, etc. Perhaps in the future we will present the results of further research to solve this problem

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The revised manuscript seems good, and authors have improved the qualification and added new contents according to my suggestions.

So I recommend accepting the revised manuscript.