Marine Organisms Rearing Test

Purpose

We will demonstrate that the water to be discharged is safe “in a visible manner”.

While ensuring safety in the design and operational management of the facilities for ALPS treated water discharge into the sea, through marine organisms rearing test, we will also demonstrate that the water to be discharged is safe “in a visible manner”, thereby reducing the adverse impact on reputation.

Disclosure of rearing condition

The following data is being disclosed in order to demonstrate in a visible manner that there is no detrimental impact on marine organism life.

  • Live video of rearing tanks can be viewed 24/7 via a webcam

    You can see the rearing condition in real time

  • Marine Organisms Rearing Log

    Click here for daily rearing condition (on web page)

  • Marine Organisms Rearing Log for Twitter

    Click here for daily rearing condition (on Twitter only in Japanese)

  • Rearing Test Monthly Report

    Click here for the rearing test monthly report

Results of rearing condition

Results and insights of tritium concentrations in flounder body

  • In graphing the measurement results, points below the detection limit and suspected adulteration were removed.
  • Similar analysis results have been reported in the following literature in the past.
    FY 2009 Experimental Study on Carbon Transfer in Land and Aquatic Ecosystems, Research Institute of Environmental Science and Technology

【Overview of the video】

Overview of the video
  • The tritium concentration in flounder body does not exceed the concentration of seawater containing ALPS treated water in which they are grown.
    【Tritium intake test】
  • The tritium concentration is maintained at the same level as the seawater in the growing environment after a certain period of time.
    【Tritium intake test】
  • The tritium concentration in flounder body quickly decreases as time passes when they are returned to normal seawater.
    【Tritium discharge test】
Referring the results of , we believe that tritium is not accumulated or concentrated.
  • The results for abalone and seaweed were consistent with the results for flounder. The OBT concentration in flounder will also be measured in the future.

Overview of rearing test

Rearing tests will be conducted in both “seawater” and “ALPS treated water diluted with seawater” and the growth of the organisms in their respective environments will be compared against each other.We will confirm that the tritium concentration in a living body reaches an equilibrium after a certain period of time and does not exceed that of the environment which it was reared in.

  • Flounder, abalone and seaweed that inhabit off the coast of Fukushima Prefecture have been selected for rearing.

    Organisms to be reared [Before the start of discharging ALPS treated water into the sea]

    Fish
    Flounder (young fish) - around 800 flounders
    Shell
    fish
    Abalone (young shellfish) - around 800 abalones
    Sea
    weed
    Sea lettuce, Gulfweed - around several kg
  • Rearing in a closed circulation system with careful handling of radioactive materials.

  • Measure and assess tritium concentration, etc. in all rearing organisms.

  • Free water tritium (FWT): Tritium that exists in the form of water in living bodies
  • Organically bound tritium (OBT): Tritium that is organically bound with carbon and other molecules in living bodies

Environment set in rearing test

  • Normal
    sea
    water
    Normal seawater [Taken from around the power station]

  • Before the start of discharge into the sea

    Condi
    tion1
    ALPS treated water diluted with seawater [Tritium concentration: approx. 1,500Bq/L]

    Considering that the operation target value of tritium in ALPS treated water after being diluted with seawater is less than 1500Bq/L, the tritium concentration in Condition 1 is adjusted to less than 1500Bq/L.

    ALPS treated water will be discharged while complying with the tritium concentration of less than 1,500Bq/LConcentration of upper limit for discharge and a total annual tritium amount of less than 22 trillion Bq

  • Before the start of discharge into the sea

    Condi
    tion2
    ALPS treated water diluted with seawater [Tritium concentration: approx. 30Bq/L]

    Considering the result of dispersion simulation that the tritium concentration around the discharge tunnel outlet is approx. 30Bq/L, the tritium concentration in Condition 2 is adjusted to approx. 30Bq/L.

    Annual average highest concentration near the discharge outlet based on dispersion simulation results(Approx. 30 Bq/L)

  • After the start of discharge into the sea

    Condi
    tion3
    Water to be discharged to the environment [Tritium concentration: approx. 1500Bq/L]

    After the start of discharge into the sea, rearing test will be conducted also in the water to be discharged (Tritium concentration of approx. 1500Bq/L).

Rearing test status

Rearing test status

Achievement so far

As the state of filtering system (bacterial colonization) and the condition of flounder growth have been confirmed to be favorable after the functionality of the rearing test tank and other equipment were verified for over a half year, the rearing test has begun on September 30, 2022.

2022

March 17

Start of rearing practice in normal seawater

Subject: 140 flounders

Rearing practice tanks

Flounder

June 9

We found parasites in a fillet of weakened flounder

For preventing the spread of parasites, we added a UV sterilizer to each tank and bathed flounder in salt water

Parasite colony

Parasite taken from flounders

July 21

Start of rearing practice in mockup tanks

Subject: 80 flounders, 30 abalones and about 2kg of seaweed

Mockup tank

Flounder

Abalone

September
13

Start of rearing in rearing test tanks for getting flounder used to the environment

Brought new 800 flounders to rearing practice tanks

Rearing test tanks

September
30

Start of rearing test

Subject: Around 800 flounder
Reference: ALPS treated water added on October 3