<p>As the demand for utilizing HPC resources in large-scale scientific computing continues to grow, LHC experiments such as ALICE are actively pursuing the integration of HPC resources into their global grid environments. However, supercomputers have structural and operational characteristics—such as system architecture, security policies, and software deployment methods—that differ significantly from those of general-purpose servers. These differences pose practical limitations to the application of existing standardized Grid integration models to HPC systems. In particular, HPC systems that require interconnection across multiple security domains face even more complex integration challenges. We propose a neutral integration strategy for HPC systems that does not depend on their specific architectures. By using existing constraints in a reversed way, the approach allows flexible integration with minimal service interruptions and operational overhead, even during infrastructure changes like system upgrades or migrations. This method was applied to Nurion, the national supercomputer operating across multiple security domains, and successfully integrated it into the ALICE Grid Site. Over approximately 17 months of operation, the site demonstrated stable job processing and efficient utilization of multicore resources. We also found CPU over-consumption behavior in the ALICE middleware through continuous system monitoring. By presenting a feasible and system-independent strategy for HPC integration, this paper offers a practical reference architecture for building next-generation HPC-based grid computing infrastructures in preparation for the HL-LHC era, where upgraded detector performance will require even greater computational capacity.</p>