Fuel Assembly
Structured bundle of 200-300 fuel rods, spacers, and guide tubes in a square lattice. Core building block delivering ~100 MW thermal per assembly in PWRs.
PWR assemblies are 4m long, 21cm square, with 17x17 rod arrays (e.g., Westinghouse design). BWR assemblies use 8x8 or 10x10 cruciform patterns. Replaced every 12-24 months; fresh assemblies cost $5-10M each. Hold ~500 kg UO2.
Why it matters now
Standardized assemblies critical for SMR licensing (e.g., NuScale) and data center PPAs in 2025-2026. ATF upgrades target existing fleets.