The absorbing elements of the control and protection system in a VVER-1000 nuclear reactor are essential for maintaining operational stability and ensuring safe shutdown during emergencies. Their performance and reliability are critically dependent on the structural integrity of the enclosing shells, which are subjected to the combined effects of assembly welding and operational thermomechanical loading. However, these factors may introduce stress concentrations and structural weaknesses, particularly in the weld regions, posing a potential risk to the long-term reliability of the system. Using finite element modeling of the welding process and subsequent thermal–mechanical loading, the evolution of stresses in the weld area was investigated. Additionally, brittle fracture resistance was assessed through a postulated defect approach, enabling the determination of quantitative strength parameters of the absorbing elements. The analysis revealed that stress triaxiality in the weld zone results in the highest susceptibility to failure in the subsurface region. These findings provide a foundation for refining procedures for instrumental monitoring of the condition and reliability of the control and protection system.