RadSed-INT: A Scenario-Aware Protocol for Radioactivity Assessment in Dynamic Beach Sediments

Beach sediments may contain natural radionuclides, fallout-derived radionuclides, naturally occurring radioactive material (NORM) or technologically enhanced naturally occurring radioactive material (TENORM), but their radiological significance depends on sediment dynamics and exposure scenario as much as on bulk activity concentration. RadSed-INT is introduced as a tiered field–laboratory protocol for assessing radioactivity in dynamic beach sediments. The protocol links in situ gamma screening, statistically designed transects, primary/confirmatory A/B sampling, high-purity germanium (HPGe) gamma-ray spectrometry, grain-size and heavy-mineral partitioning, vertical mini-core radiostratigraphy, and triggered dust, radon/thoron and ingestion pathway modules. Its central requirement is radiometric mass closure between directly measured bulk activity and the mass-weighted reconstruction from sediment fractions. External and internal doses are evaluated only for explicitly defined material status, exposure pathways, occupancy assumptions and regulatory domains; construction-material and NORM indices are retained as context-specific comparators, not universal beach-sediment limits. RadSed-INT defines escalation triggers from reconnaissance to confirmatory spatial, grain-size, vertical or aerosol investigations. This article is methodological and does not report new primary field data. Supplementary Material provides extended notation, a date-sensitive regulatory matrix, confounder checklists, implementation tables and a minimal worked example, while the main text retains the core protocol logic.