A Possibility for Large-Scale Production of 238Pu in Light-Water Reactor VVER-1000
, Nikolay I. Geraskin, Vladimir A. Apse, Vasily B. Glebov *, Gennady G. Kulikov and Evgeny G. Kulikov
Joseph R. Burns
Round 1
Reviewer 1 Report
Abstract - clarify the sentence about the specific Pu-238 production (i.e., explicitly mention Pu-238 kg per NpO2 kg).
Abstract - consider quantifying the "remarkably larger" statement - larger by what factor/percentage?
Section 1 - I'm not sure references 1 and 2 support the assertion that US production capabilities do not keep up with demand, but the HFIR and ATR production numbers do. Include the HFIR and ATR references here.
Section 1.1 - Include a reference supporting the Pu-238 production cost per kg.
Section 1.1 - Consider including Pu-238 reaction cross sections to clarify how Pu-238 mass can be reduced while trying to produce it.
Section 1.2 - Consider annotating Figure 2 to show the desirable/undesirable energy ranges and including the capture/fission ratios.
Section 1.3 - Include a reference for the global share of Mayak radioisotope production.
Section 1.3 - Include a reference for the claim of 5 kg Pu-238 supporting 3-5 satellites' RITEGs.
Section 2.1 - Include a discussion here on the physical mechanisms of neutrons slowing down in natural Pb and Pb-208. What reactions are relevant for improving Pu-238 production, as well as for the impact on doppler coefficient and mean neutron lifetime?
Section 2.1 - What is the composition of the NpO2 rods? Is any Al included?
Section 2.2 - Are there any other model visualizations available? Consider including here for clarity.
Section 2.2 - I'd like to see more thorough discussion of the computational workflow. I.e., are cross sections generated for each of the 8 cylindrical reactor layers? Is the diffusion calculation 3D? Any divisions in the axial dimension? How much detail is lost in assuming cylindrical geometry? Is the cylindrical geometry assumption standard practice for VVER calculations? Fresh core composition, or equilibrium? Are control elements present? What other assumptions are made in the model?
Section 3.1 - What is the cycle length? Are outages included in the calculations?
Section 3.1 - In variant 1 (the reference core), is Pu production still assessed in the central FA, as in the variants with the ID included?
Section 3.1 - What are the neutronic mechanisms affecting Pu-238 production in each variant? What are the relevant reactions in light water, natural Pb, and Pb-208?
Section 3.1 - Clarify whether the pitch parameterization studies are carried out by keeping the number of rods constant and varying the rod size. Any changes to the cladding dimensions?
Section 3.1 - Clarify that the first set of pitch parameterizations were carried out with natural lead.
Section 3.1 - Clarify the units of the y-axis of Figure 7. Is it kg Pu/year/kg Np? Is it total Pu or Pu-238?
Section 3.1 - Consider dividing this section into further subsections, one for Pu production in each variant, one for pitch parameterizations, etc.
Section 3.2 - What strength properties are impacted by DDD? Yield strength, ductility, etc.? What properties are most relevant and under what reactor conditions?
Section 3.2 - What displacement cross section data are used? How is this calculation run?
Section 3.2 - Consider plotting DDD for each ID variant all on one plot to highlight minimal impact to vessel dpa. Also explicitly indicate which layer includes the vessel. Then include perhaps one other plot to highlight the impact of water gap thickness.
Section 3.2 - Not necessary to include, but it would be interesting to see the impact on vessel dpa if the ID is moved away from the center, even if not practical for maximizing Pu production.
Overall - What other reactor performance indicators are impacted by including the ID? Do we lose cycle length due to removal of U, and do we need more enrichment to recover it? Impact on other safety-relevant parameters? I think including some brief studies on these considerations is important.
Overall - What do you envision for putting this into practice, and what are your recommendations? Could all VVERs do this? Are there numbers available to compare specific Pu-238 production to ATR and HFIR? Sounds like it could be a game-changer for Pu-238 production.
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
This a very good work and well written manuscript. Text material is all right. Few English mistakes are there in the text, which have been given below. However, there is big confusion between choosing the heading results and discussion. The discussion part is looking like a long conclusion. I feel, one heading can be results and discussion. The other part should be conclusion. So the manuscript be accepted in JNE after its minor revision.
Needed corrections and suggestions
Abstract
1. Page 1. ---around of the NpO2 assembly---
Change as
---around the NpO2 assembly---
Keywords
2. Page 1. “plutonium isotope 238Pu” is not necessary
1. Introduction
1.1. 238Pu production in nuclear reactors.
3. Page 2. --- US dollars per one 238Pu kilogram.---
Change as
--- US dollars per one kilogram of 238Pu.
1.2. Isotope 237Np as a starting material for 238Pu production
4. Page 3. ---can initiate both fruitful 237Np(n,γ)238Pu reaction and useless 237Np(n,2n)236Pu reaction.
Change as
---can initiate fruitful 237Np(n,γ)238Np reaction and useless 237Np(n,2n)236Np reaction and their respective decay products 238Pu and 236Pu.
1.3. 238Pu production in the Russian Federation and in the USA
5. Page 4. ---(for instance, [1, 7, 11])---
Change as
---(for instance, Refs. [1, 7, 11])---
6. Page 4. ---are able intensify fruitful 237Np(n,γ)238Pu reaction and, at the same time, to suppress undesirable 237Np(n,2n)236Pu reaction which can be---
Change as
---are able intensify fruitful 237Np(n,γ)238Np reaction and, at the same time, to suppress undesirable 237Np(n,2n)236Np reaction, which can be---
7. Give the full form of ATR
2. Materials and Methods
2.1. Method of 238Pu production
8. All right
2.2. Mathematical model
9. All right
3. Results
10. Since measure part of discussion is there in the results part, heading can be as follows.
3. Results and discussion
3.1. Variants of the ID design and evaluations of 238Pu production
11. Page 8. ---237Np(n,2n)236Pu reaction rate.
Change as
---237Np(n,2n)236Np reaction rate.
3.2. Analysis of the displacement damage dose
12. Page 9. This statement is correct for all chemical elements which can be used as constituents of metal structures in nuclear reactors.
I feel, one comma is missing. So change as
This statement is correct for all chemical elements, which can be used as constituents of metal structures in nuclear reactors.
4. Discussion
13. Measure part is the conclusion. Discussion part has gone in the results part. If want to keep the results and discussion part as heading as mentioned before then the discussion heading can be a conclusion, which is long. Then make the heading as follows.
4. Conclusion
14. It can be a long conclusion. If possible some part of this can go in the earlier section.
15. If some part will go the earlier section, write the conclusion part in proper way
16. In summary, text is all right. However, confusion between the headings results and discussion. I feel, one heading can be results and discussion. The other heading should be conclusion. So choose the text materials accordingly.
Author Response
Please see the attachment
Author Response File: Author Response.docx
