[Research]: Investigate IAEA/NIST isotopic abundance data aggregation

[bryanchriswhite]

Background

Issue #96 (Weighted Fuel Proportions and Materials Catalog) currently uses the existing pcaNCrust field from the NuclidesPlus database table for natural isotopic abundances.

Research Objectives

1. Compare data sources: Evaluate differences between:

   • Current pcaNCrust field (Earth's crust abundance)
   • IAEA Nuclear Data Services isotopic abundances
   • NIST Atomic Weights and Isotopic Compositions

2. Assess accuracy: Determine which source provides the most accurate natural isotopic abundance data for LENR simulation purposes

3. Evaluate aggregation strategy: Determine if/how to aggregate multiple data sources:

   • Use IAEA/NIST as primary with DB fallback
   • Store multiple abundance types (crust, solar, natural)
   • Allow user selection of abundance source

4. Implementation pathway: Document viable approaches for importing authoritative abundance data

Data Sources

• IAEA Nuclear Data Services: https://www-nds.iaea.org/
• NIST Atomic Weights and Isotopic Compositions: https://www.nist.gov/pml/atomic-weights-and-isotopic-compositions

Related

• Parent issue: [Feature]: Weighted Fuel Proportions and Materials Catalog for Realistic Cascade Simulations #96

Deliverables

• Comparison document showing differences between data sources
• Recommendation for implementation approach
• Draft schema changes (if needed)

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Note: This is a follow-up research task identified during Issue #96 implementation.

[esaruoho]

Research Findings: IAEA/NIST Isotopic Abundance Data

I've investigated the three data sources mentioned in this issue. Here's a summary:

Current pcaNCrust Column

Despite the "NCrust" suffix, the pcaNCrust values are actually natural isotopic abundances (mole fraction percentages), NOT Earth's crust abundances. The ppmNCrust column contains actual crustal abundances. Spot-checking against NIST:

Nuclide	pcaNCrust (%)	NIST/CIAAW (%)	Delta
H-1	99.9850	99.9885	0.0035
D	0.0150	0.0115	0.0035
Li-6	7.4200	7.59	0.17
Li-7	92.5800	92.41	0.17
Ni-58	67.7700	68.0769	0.31

The Parkhomov values appear to be from an older IUPAC evaluation (pre-2009), with differences in the 0.01-0.5% range.

Data Sources Compared

Aspect	IAEA LiveChart	NIST
API	REST CSV: nds.iaea.org/relnsd/v1/data?fields=ground_states&nuclides=all	CGI ASCII: physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ascii=ascii
Data vintage	NuBase 2020 (latest)	CIAAW 2009/2013
Uncertainties	Yes (unc_a column)	Yes (parenthetical notation)
Format	Clean CSV	Custom key-value ASCII (needs parser)
Coverage	~3,340 nuclides, ~290 with abundance	~400 isotopes listed, ~290 with abundance
License	Free with IAEA attribution	US Gov public domain
Auth required	No	No

Both ultimately derive from IUPAC CIAAW (the international authority since 1899). IAEA is more recent (NuBase 2020 vs NIST's 2009/2013 data.

Recommendation

Use IAEA LiveChart API as primary source (fetched at build time, not runtime):

1. Add a build script to that fetches IAEA ground states CSV

2. Add columns to :

3. Retain for backward compatibility

4. Optionally cross-validate with NIST data

5. UI: offer abundance source selector in cascade simulations

Estimated effort: 1-2 days for data import + schema change, 1 day for UI toggle.

Useful Links

• IAEA LiveChart API Guide
• IAEA API Notebooks (GitHub)
• NIST Isotopic Compositions
• IUPAC CIAAW
  ENDOFCOMMENT
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[bryanchriswhite]

Investigation graduated into implementation — src/constants/iaeaAbundances.ts is a 2,089-line dataset landed by #155 alongside scripts/fetch-iaea-abundances.cjs. Closing as superseded.