For reactor nuclear power plants built, the noun “Components structural integrity” for metal SSCs is required to consider the potential consequences of structural failure of SSCs and whether there is protection and mitigation against these consequences. The structural integrity class includes High Integrity Component (HIC), Structural Integrity Class 1 (SIC-1), Structural Integrity Class 2 and 3 (SIC-2, SIC-3). For HICs, because of unacceptable consequences after their failure, probability of the failure should be extremely low so that their gross failure can be discounted. There are many internal hazards sources located in nuclear power plant which can impact on HICs. Therefore a safety case is expected to demonstrate that the SSCs with highest reliability claims are not challenged by internal hazards such that the estimated likelihood of gross failure is very low. Therefore, it is required that the HICs functionality is not challenged by internal hazards, and that eliminating hazards scenarios impacting on HICs is the preferred option for the layout and design of the plant. For nuclear power plants, no practicable methods have been presented yet to be used for HICs against internal hazards. Through the systematic research of requirement for HICs against internal hazards, the failure mode of equipment against internal hazards and scenarios of internal hazards impacting HICs, this paper introduces protection strategy and assessment method for HICs against internal hazards. This general protection strategy and assessment method based on the deterministic approach could be used as guidance for HICs against internal hazards safety evaluation for nuclear power plants.