Filing is concentrated: the top 5 assignees hold 51.0% of all 51 records in scope, and the top 10 extend that to 80.4%. The leading single assignee holds 6 records, with a gradual drop to 4 at fifth place and 3 at tenth, meaning several holders occupy comparable positions rather than one company dominating outright. Anyone entering this space should expect to file adjacent to an established, if not enormous, set of incumbents.

No — filing peaked in 2018 at 9 records and the 2022 midpoint reads zero, indicating a flat-to-declining trend rather than continued growth. The most recent year is always undercounted because publication typically lags filing by around 18 months, so the true 2025-2026 picture will fill in somewhat as records publish. Even accounting for that lag, the multi-year decline from the 2018 peak is the dominant signal.

Every record in this dataset carries the core G21F radiation-protection classification by design of the search. Beyond that, C08K (polymer additives) appears in 25.5% of records and G21C (nuclear reactor context) in 15.7%, making polymer-composite formulation the more active secondary claim area compared to reactor-specific shielding engineering. Smaller classes — C08L, C01B, C08J, C08F, B64G — each cover single-digit percentages, pointing to niche applications like spacecraft shielding.

The thinnest-covered secondary classes in this dataset — C08F addition polymers at 3.9% of records and B64G spacecraft applications at 2.0% — suggest under-claimed ground in vinyl-polymer-based composites and space-application shielding. Computational design approaches for attenuation coefficients, as seen in the King Saud University filing, also appear lightly represented relative to the empirical formulation claims that dominate the set. Any white-space claim should be checked against a fuller search before committing, since this dataset is narrowly scoped.

US20190378628A1, filed by King Saud University and published in December 2019, claims a computational method for selecting a polymer, a metal, and a polymer:metal ratio, then calculating an attenuation coefficient to identify the best-performing candidate before preparing the material. It is a method claim over a design workflow, not a composition-of-matter claim over any specific shielding material — so it constrains automated screening approaches that follow this same select-compute-identify-prepare sequence, but does not by itself block someone formulating a shielding composite through empirical testing rather than computational candidate selection. A freedom-to-operate review should check this claim's exact scope language against any planned computational screening pipeline.