Underwater acoustic sensor networks (UASNs) have gained increasing importance in various military and civilian applications due to their ability to facilitate communication in challenging underwater environments. However, routing in UASNs faces unique challenges stemming from the harsh characteristics of underwater acoustic communication caused by water currents and node mobility. This work suggests a comprehensive routing framework that uniquely integrates void avoidance with intelligent, deep reinforcement learning-based routing techniques.The contribution from this research is the performance of void avoidance and routing for the effective transmission. Specifically, a novel HH-VBF (hop-by-hop vector-based forwarding) method is employed to detect and eliminate the void nodes, thereby enhancing reliability and reducing packet loss. Furthermore, the proposed deformable bi-level routing attention-based multi-agent adaptive deep deterministic policy gradient (DBRAMADDPG) algorithm, optimized using the improved nuclear reaction optimization algorithm (ImNROA), dynamically learns optimal routing paths to reduce end-to-end delay and energy consumption by avoiding the void area.This unified approach can effectively mitigate void-induced disruptions while balancing energy efficiency, extending the network lifetime, and improving the quality of service. Extensive simulations demonstrated that our model outperformed existing methods, reducing delay by up to 7%, while taking the number of nodes as 10, the delays of the IR2P (intelligent reinforcement learning routing protocol with integrated power-control), HMERP (hybrid message encoding-based routing protocol), ROAR (resource-optimized adaptive routing), VAHR (void-aware hybrid routing), and the proposed ImNROA-DBRAMADDPG were 0.8948%, 0.8639%, 0.84533%, 0.80878%, and 0.78594%, respectively, ensuring more stable data delivery in complex underwater scenarios.These advancements contribute to the state of the art by offering robust routing strategies capable of dynamically adapting to underwater environmental challenges and void formations. The findings provide potential implications for designing resilient and energy-efficient UASNs, paving the way for improved real-time underwater monitoring and secure acoustic communication systems. These findings pave the way for more reliable, sustainable, and intelligent underwater sensor networks, with significant implications for real-time marine exploration, defense, and environmental monitoring.
Accident-tolerant cladding for water-cooled reactors requires materials capable of withstanding severe transients, including loss-of-coolant accidents (LOCA), station blackout (SBO), and loss of heat sink, while preserving acceptable neutron economy. This study investigates the neutronic feasibility of two yttrium-based ceramic oxides, Y2Sn2O7 and Y2TiO5, as alternative fuel cladding materials in a VVER-1200 reactor using full-core continuous-energy Monte Carlo simulations with Serpent 2.1.31. A realistic VVER-1200 core model with 163 fuel assemblies, enrichment zoning, and gadolinia-bearing fuel was employed, and the effect of cladding replacement was isolated by preserving all non-cladding parameters of the reference E110 alloy design. The computational methodology was supported by code-to-code comparison with OpenMC using ENDF/B-VII.1 nuclear data. The results indicate that both candidate materials impose negative reactivity effects over the entire depletion interval, but with markedly different severity. Relative to the reference core, Y2Sn2O7 caused a moderate beginning-of-life reduction in keff from about 1.16 to 1.13, while Y2TiO5 lowers it to about 1.10. The corresponding reactivity penalties are approximately -2200 pcm for Y2Sn2O7 and -5000 to -3700 pcm for Y2TiO5 over depletion. Although the thermal neutron spectrum remains generally preserved, Y2TiO5 induces greater spectral hardening and a larger neutronic departure from the reference case. The analysis uses a fixed-loading depletion history; results beyond the calculated criticality crossings are treated as exploratory numerical continuations rather than predictions of sustained reactor operation. These findings identify Y2Sn2O7 as the more promising of the two investigated ceramic cladding options from a neutronic perspective, and they provide reactor-specific evidence supporting its further evaluation in coupled thermal-hydraulic, structural, and safety analyses for VVER-1200 accident-tolerant fuel design.
