2.7. Protection of Present and Future Generations and their Environment

People and the environment, present and future, must be protected against radiation risks.

The protection of future generations and the environment is an important concept that is, embedded in the concepts of justification, optimization and the limitation of risk to the individual. Nonetheless, it is presented separately in the international safety standards. This fundamental safety principle simply requires that people and the environment, present and future, must be protected against radiation risks.

As part of its activities, the Government of Japan and TEPCO must take into account that radiation risks attributable to the discharge might transcend national borders and may persist for long periods of time. Thus, the measures to control the discharges consider any possible consequence, now and in the future. In particular, it is important to note that the international safety standards apply not only to local populations but also to populations remote from the discharge activities; and that where effects could span generations, subsequent generations have to be adequately protected without any need for them to take significant protective actions.

This is an important fundamental safety principle given the long-term approach currently envisaged for discharging ALPS treated water at FDNPS. Through its work the IAEA has noted that the REIA produced by TEPCO and reviewed by NRA has demonstrated that the dose to representative persons in neighbouring countries will be undetectable and negligible.

In order to ensure the proper protection of future generation, the Task Force decided to corroborate that the dose commitment, rather than the dose incurred, is the fundamental quantity for determining compliance with the international safety standards. The fundamental quantity for assessing doses shall be the dose due to external exposure in a year plus the committed dose from intakes of radionuclides in that year. This means that the total annual dose calculated is that received over a lifetime (assumed to be until the age of 70) from intakes of radionuclides due to the ALPS treated water that is discharged to the sea in an assigned year.

It should be noted that the total amount of tritium, 14C and 129I to be released each year in the discharge of ALPS treated water will be well below the amount of these radionuclides produced by natural processes each year, such as interaction of cosmic rays with gases in the upper atmosphere.

Production of 3 H, 14C and 129I by natural processes

There are three main sources of natural tritium on earth: production in the atmosphere by cosmic rays; production in the atmosphere by energetic particles originated from solar coronal mass ejections; and direct accretion from the sun. Tritium produced by natural processes on earth is rapidly converted into HTO, which then enters the global hydrological cycle. The annual production of tritium due to natural processes is estimated to be around 280 grams, with annual production varying between 220 to 330 grams due to the variation in the intensity of cosmic due to the solar cycle variations.

The average value of 280 grams in a year corresponds to the activity in the order of 100 PBq (100,000 TBq) in a year. The global inventory of tritium is estimated to be about 2,000 PBq (2,000,000 TBq). The limit on the amount of tritium in the treated water to be released each year is 22 TBq. This is about 5,000 2 6 times lower than the annual production on the planet due to natural processes, and much less than the variation from year to year in the annual production.

The tritium natural background level in the Pacific Ocean is in the range of 0.1-1 Bq/L. The ocean dispersion modelling conducted by TEPCO indicates that concentrations of tritium above natural background concentrations will be limited to within 3 km of the discharge point at FDNPS. The concentration is much lower than the natural background level at the boundary of the model simulation range (490 km x 270 km), the maximum value being 0.00026 Bq/L, which is three to four orders of magnitude lower than the natural background level

The main source of natural 14C on earth is the production in the atmosphere by cosmic rays by the nuclear reaction: 14N(n, p)14C. The global inventory due to natural processes of 14C is estimated to be around 1 PBq (1,000 TBq). The amount of 14C in the ALPS treated water to be released each year is about 2 GBq (0.002 TBq), which is about 500,000 times lower than the global inventory due to natural processes.

Iodine-129 is produced by the following natural processes: reactions of cosmic rays with xenon in the upper atmosphere; spontaneous fission of 238U; thermal neutron induced fission of 235U; and neutron activation reactions 128Te(n,γ) 129I and 130Te(n,2n)129I. . It is estimated that the global inventory of 129I due to natural processes in the hydrosphere (primarily oceans) is about 1 TBq. The amount of 129I to be released in the treated water each year is 30-300 MBq. This is about 3,000-30,000 times lower than the steady state inventory of naturally occurring 129I in all of the oceans.

The Task Force has also considered that whereas the effects of radiation exposure on human health are relatively well understood, albeit with uncertainties, the effects of radiation on the environment are under continuous investigation by science. The system of radiation protection established by the international safety standards provides appropriate protection of ecosystems in the human environment against harmful effects of radiation exposure. The general intent of the measures taken for the purposes of environmental protection has been to protect ecosystems against radiation exposure that would have adverse consequences for populations of a species, rather than focusing on individual organisms.

Protection of the Environment

The environment is defined in the international safety standards as “The conditions under which people, animals and plants live or develop and which sustains all life and development, especially such conditions as affected by human activities”

Protection of the environment is defined is defined as “Protection and conservation of non-human species, both animal and plant, and their biodiversity; environmental goods and services, such as the production of food and feed; resources used in agriculture, forestry, fisheries and tourism; amenities used in spiritual, cultural and recreational activities; media, such as soil, water and air; and natural processes, such as carbon, nitrogen and water cycles.

The high-level aim of the protection of the environment set by the ICRP is to provide for the maintenance of biological diversity and to ensure the conservation of species and the health of natural habitats, communities, and ecosystems. The radiation risk to populations of flora and fauna are expected to be negligible. The methods used for the assessment of the impact on flora and fauna are based on the current scientific knowledge of radiation effects.

The IAEA international safety standards are in agreement with the international environmental protection objectives of maintaining biological diversity, ensuring the conservation of species, and protecting the health and status of natural habitats, communities, and ecosystems

TEPCO followed a methodology for assessing the impact on flora and fauna provided in the international safety standards that is in line with the ICRP approach for the protection of different ecosystems in the environment. Consistent with this approach, three species are used as references for the protection of the marine environment. The conceptual approach is that, if the criteria for those three reference species is not exceeded, then all the species can be assumed to be equally well protected, at the level of their populations (particularly for planned exposure situation). The three reference species are:

? Flat fish (Left-eyed and right-eyed flounders widely inhabit the sea area around the FDNPS)

? Crabs (Ovalipes punctatus and Portunus trituberculatus widely inhabit the sea area around the FDNPS)?

?? Brown seaweeds (Sargassum and Eisenia bicyclis widely inhabit the sea area around the FDNPS

These plants and animals are widely distributed in the sea area around the FDNPS, so the radioactive material concentration in the seawater used for the assessment is for a reference area around the discharge point where the highest environmental activity concentrations typically occur line with the generic methodology in the international safety standards. For further details refer to Part 3 (Section 3.4). In addition, in the assessment of dose rates to plants and animals, external exposure is calculated from radionuclides seabed sediments, as well as those suspended in the seawater, to take account of fish that live on the seabed (reference flatfish).

The exposure results are for Flatfish 0.0000007 (0.7 E-06) mGy per day, for Crab 0.0000007 (0.7E-06) mGy per day and for Brown seaweed of 0.0000008 (0.8 E-06) mGy per day. These values are well below the Derived Consideration Reference Level (DCRL) provided as an example in the international safety standards and established by ICRP.

While the Task Force is aware that the behaviour of radioactive substances in the environment is complex, it holds the view that the requirements of the international standards on environmental protection have been respected and that radiation exposure to the biota attributable to the discharge will not be expected to be a noteworthy consideration in meeting these objectives. The Task Force also underline its concurrence with the international consensus, expressed in ICRP recommendations, that the standards of control of discharges (planned exposures) needed to protect the general public, which are being fully applied to the discharges, would generally ensure that other species are not put at risk.

The IAEA is confident that the international environmental protections objectives will be amply met by the controls in place for the discharge of ALPS treated water and that the dose rates to biota are negligible compared to the international safety criteria set by ICRP.

In summary, the discharge of the water must be managed to protect future generations and their environments in such a way as to avoid imposing an undue or uncontrolled burden on future generations. TEPCO must apply safe, practicable, and environmentally acceptable solutions for its long-term management of ALPS treated water. The IAEA notes that the existing assessment and controls conducted for the planned discharge of ALPS treated water from FDNPS appear to satisfy this principle

Conclusions

? TEPCO has carried out a REIA for the discharge of the ALPS treated water, in line with the international safety standards

?? An assessment of the radiation dose to the public considering all situations, and an assessment of the radiation dose rates to marine animals and plants in normal operation was carried out.

? It also has been confirmed that the evaluation result of radiological impact on animals and plants in the sea by the discharge of ALPS treated water under normal operations is negligible.?

? The results of the radiological environmental impact assessment show that the estimated dose to populations in neighbouring countries will be negligible.

? TEPCO’s marine dispersion models predict very insignificant concentrations of tritium and other radionuclides that will be undetectable or indistinguishable from background levels at the boundary of the modelling simulation area.

Derived Consideration Reference Level

The ICRP has defined criteria for assessing and managing the radiological impact on animals and plants in the form of “derived consideration reference levels” [12]. Derived consideration reference levels span one order of magnitude; for dose rates below the lower bound of the bands, no effects have been observed or no information on effects is available.

Derived consideration reference levels do not represent limits; rather, in accordance with ICRP recommendations [12] they should be considered as points of reference for informing the appropriate level of effort that should be expended on environmental protection, dependent on the overall management objectives, the actual flora and fauna present, and the number of individuals exposed [12, 13].