On 2 May 2014, Japan provided the IAEA with an update to current information on radioactivity in seawater at TEPCO's Fukushima Daiichi Nuclear Power Station (NPS).
The update shows that all radionuclides (i.e. Cs-134, Cs-137, total Beta and H-3) have remained at a low level as indicated in the data collected from 21-28 April 2014 at the sampling points T-1 and T-2-1. These sampling points near Fukushima NPS are sentinels to assess effects on the environment by incidents including a leakage of contaminated water.
The NRA also provided an update on the sea area monitoring results for radioactivity obtained from sea water samples taken at a distance of 2 to 200 kilometres from TEPCO's Fukushima Daiichi NPS.
TEPCO also provided a document outlining an agreement they signed with Sellafield, which is available here.