Improvement of the Advanced Environmental Transfer and Dose Assessment Model forRadionuclides Released from the Nuclear Fuel Reprocessing Plant in Rokkasho
Koichi ABE, Takashi IYOGI, Hidenao HASEGAWA, Shinji UEDA, Shun’ichi HISAMATSU
Department of Radioecology
Abstract
We have developed the advanced environmental transfer and dose assessment model (AdvETDAM) forradionuclides released from the first Japanese commercial nuclear fuel reprocessing plant located in Rokkasho.
The computer code system was developed on personal computers to describe atmospheric dispersion, terrestrial
and aquatic transfers, and dose calculations for the released radionuclides. AdvETDAM consists of an atmosphericdispersion model with a meteorological model (MM5), a terrestrial transfer model, an aquatic transfer model for
Lake Obuchi, which is a brackish lake neighboring the reprocessing plant, and its catchment area, and a coastal
marine model for the Rokkasho coast.
In FY 2015, to describe radionuclide transfer in Lake Takahoko, which is another brackish lake near thereprocessing plant, and its catchment area, radionuclide transfer models were coupled with the hydrologicalmodels in the lake and the catchment area, followed by their integrating with AdvETDAM as its sub-models. In
order to check operation of AdvETDAM including those sub-models, a test calculation was conducted for theperiod when higher 3H concentration than background level was detected in the lake water. AdvETDAM fairly
well simulated the flow of 3H, which was released into the Pacific Ocean from the plant, through the channel tothe lake and retention there.
To check the contributions of each parameter to variation of dose rate to human beings, a sensitivity analysis
module with uncertainty propagation analysis were installed to AdvETDAM. In addition, the atmosphericdispersion sub-model was modified to improve accuracy of simulated atmospheric concentration and depositionof 129I.
To validate the atmospheric dispersion and terrestrial transfer sub-models, the outputs of these sub-models
were compared with those of ATRENO/TERFOC-N, which has the logic used for the safety review of thereprocessing plant. Although the maximum concentrations and depositions of radionuclides were comparable
between the ATRENO/TERFOC-N model and AdvETDAM, the locations of the maximum values were different
between the two. Further study for the radionuclide distribution around the reprocessing plant is required tovalidate AdvETDAM.

a) Simulation results by ATRENOb) Simulation results by AdvETDAM

Fig. 1 Distribution of cumulative atmospheric 3H concentration simulated using the source term in the safety reviewof the reprocessing plant in Rokkasho and meteorological conditions in 2007. a) and b) are simulation resultsby AdvETDAM and ATRENO, respectively.

Table 1 Maximum annual dose to public simulated using the source term in the safety review of the reprocessingplant in Rokkasho and meteorological conditions in 2007 by AdvETDAM and ATRENO/TERFOC-N.

AdvETDAM

Maximum annual dose (mSv)
ATRENO/TERFOC-N

Safety review *Kr

6.0E-03

5.7E-03

5.3E-03H

1.9E-03

3.9E-03

2.8E-03

3.6E-03

2.4E-02

7.7E-03I

8.3E-05

9.8E-04

6.7E-04Sr

2.3E-05

2.7E-05

4.5E-05

3.0E-04

2.2E-04

5.7E-04

1.9E-05

6.1E-05

1.4E-04

1.2E-02

3.6E-02

1.7E-02

Radionuclides
85
314C
12990106

Ru137CsSum* The dose in the safety assessment using meteorological conditions during December 1985-November 1986.