In April, Tepco released highly contaminated water to the sea.
In May, Tepco announced the leaked Iodine and Cesium are “ONLY” 4,700 trillion Bq, which is less than 5,200 trillion Bq leaked from Sellafield in England.
However, this assumption does not include the leakage in March. If they include it, it may be the worst sea contamination in history.
In October, IRSN re-estimated that even if you only count Cs-137, it’s 27 quadrillion Bq, which is 28 times worse as Tepco’s report.
Japanese scientists try to deny the number by saying sea should dilute the cesium.
(Source)