EPRI Core Protection NANTeL Practice Test 2026 – Complete Exam Prep

The first barrier to fission product release is the fuel itself—specifically the fuel pellet and its cladding. Fission products are formed in the fuel matrix and are initially contained within the pellet; the surrounding cladding (the metal tube around the pellet) provides the first containment boundary. If the cladding remains intact, these fission products stay isolated from the reactor coolant. Only if this barrier is breached could materials enter the coolant and move toward subsequent barriers. The next barriers, in order, are the reactor coolant system boundary, then the containment, which finally prevents any release to the environment. Shielding serves to protect workers from radiation, not to serve as a containment barrier for fission products.