Constraint-Based Disassembly Sequencing Algorithms for Dismantling Applications—A Comparative Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript Disassembly Sequencing Algorithms for Nuclear Decommissioning -A Comparative Study is undoubtedly of scientific interest.
The authors provide a comprehensive review of known algorithms for cutting and dismantling various industrial structures and facilities. At the same time, they note that there are no tried-and-tested algorithms for the safe dismantling of nuclear power plants in the nuclear industry. Although in today’s reality, it is important for the development of robotic dismantling systems to plan and execute complex engineering operations while minimizing human involvement in hazardous areas. This confirms the high relevance and novelty of the presented work. The authors have done extensive work in developing four algorithms, comparing their parameters, and seeking ways to optimize them. Overall, the work appears well-structured, the narrative is logical and clear, and the level of English corresponds to that of a scientific journal.
However, a weakness in the practical application of these algorithms is their idealized representation of the geometry and the dismantling process (the algorithms are designed solely to cut objects and remove them safely).I understand that this paper outlines the first steps in this direction; nevertheless, the title of the article suggests that it will focus on the decommissioning of nuclear power plants. Therefore, if the authors focus on a more realistic object, such as a reactor vessel, it will become clear that these algorithms will require significant adjustment and refinement. 
This raises questions : (1) Can these algorithms be applied in real-world scenarios? (2) How versatile is the proposed approach? (3) What are the limitations? (4) What kind of input data is required to get started?
Thus, to better understand the importance of this research, the authors are advised to include information on the intended practical application of these algorithms. For example, they could consider a hypothetical case (a nuclear power plant steam generator, a hull, etc.). This would clarify many aspects, ranging from the input data (structural geometry, components, materials, etc.) to the potential limitations of these algorithms.
If the authors believe it is still too early to discuss the practical application of these algorithms, then it is recommended that they revise the title, abstract, and introduction to focus solely on the problem of algorithm development and avoid any mention of nuclear power plants.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The study addresses an important problem of decommissioning of the large structures. A computational approach for determining the optimal path of structure disassembly is proposed and four algorithms were compared in the paper: First Feasible Random Search (FFRS), Greedy Search (GS), Height-Decreasing Search (HDS), and Stochastic Tree Search (STS). The comparative analysis was performed and results showed pros and cons of each algorithm in a given situation.

Despite the overall good quality of the research its title does not correspond to the content of the paper. The paper does not address the uniqueness of the Nuclear Decommissioning, namely: the study does not address the problem of the radioactive contamination of the objects that are subject to disassembly. This crucial constrain is unique for nuclear decommissioning and must be considered in the study, that claims to address this problem for nuclear decommissioning. Through the whole narrative of the paper no clear examples of constructions undergoing disassembly that are typical to nuclear facilities were given. No consideration regarding activation and radioactive hot spots were given in the paper. 

This study is more suitable for a general decommissioning process rather than specific for nuclear facilities. Either the title of the paper should be changed, or the study should undergo significant re-work.

Additional comments regarding the narrative.

Line 38. Formatting of the number is broken.
Line 40. RPVs, pipe network and gloveboxes are on significantly different scales of sizes. It is not appropriate to put them together as a group.
Line 50-51. "... prior knowledge and engineering judgment". Priore knowledge of what? Engineering judgment of what? This statement is to ambiguous and should be more specific.
Line 55. "...consistently and at greater speed than manual approaches, ..." What this statement is based on? The statement has no support in the narrative or references.
Lines 153-157. Problem description is too general and does not address any specifics of nuclear facilities.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This paper compares four algorithms for solving the disassembly sequencing problem in two dimensions. It was observed that  Stochastic Tree Search consistently finds optimal or near-optimal solutions, its factorial runtime limits scalability, whereas  Greedy Search approach produces high-quality solutions efficiently but can become trapped in infeasible configurations. At the same time, Height-Decreasing Search offers strong reliability and speed at the expense of solution quality. On the base of obtained results, authors proposed a hybrid height-based backtracking algorithm to optimize the serarching process. It was noted that such approach combine the efficiency of greedy search with the robustness of stochastic exploration. It was concluded that observed strengths and limitations of different sequencing strategies can be useful for future extension to 3D robotic disassembly applications. Paper is well-organized and well-written, so it can be accepted in present state.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Corrections made are reviewed and are expectable. The focus of the paper shifted towards the algorithm itself rather than on direct implementation into nuclear decommissioning. No additional comments.