Short answer: Indonesian measurements don’t show a persistent Fukushima signal. Monitoring since 2011 finds very low Cs-137, and Cs-134 (the Fukushima “fingerprint”) was below detection—so what’s in Indonesia is overwhelmingly legacy fallout from older nuclear testing.
Here are the key data points:
- Coastal Indonesia (2011–2013): Seawater 0.12–0.32 Bq/m³ Cs-137; sediments 0.10–1.03 Bq/kg. Fukushima-specific Cs-134 was not detected, implying no measurable Fukushima input at those sites.
- Indian Ocean off West Sumatra & South Java (2015 study): Surface seawater <MDA to 0.13–0.28 Bq/m³ Cs-137; Cs-134 < MDA. Authors conclude these waters “have not yet been influenced by the Fukushima radioactive release.”
- Lombok Strait / Indonesian Throughflow monitoring: Follow-on work mapping Cs-137 in outflow waters (no persistent Cs-134 detected) supports that Indonesian levels largely reflect background from historical testing, with transport shaped by Pacific→Indian Ocean flow.
- Global/Regional context (UNSCEAR): Fukushima released Cs-137 and Cs-134 that were detected worldwide in 2011 at trace atmospheric levels; long-term environmental levels outside Japan (including SE Asia) are dominated by pre-1980s test fallout.
Bottom line for Indonesia
- Air (2011): Brief, very low Fukushima-related traces likely passed through, consistent with global measurements, then decayed/dispersed.
- Oceans & coasts (2011–present): No sustained Fukushima signature; current Cs-137 is low and attributable to older sources.
If you’d like, I can pull specific sites (e.g., Java Sea vs. Sulawesi vs. Lombok) and lay out a tiny table of measured ranges and detection limits.
