Characterization of bremsstrahlung and -rays of fuel debris

松村 太伊知; 奥村 啓介; 藤田 学*; 坂本 雅洋; 寺島 顕一; Riyana, E. S.

Radiation Physics and Chemistry, 199, p.110298_1 - 110298_8, 2022/10

https://doi.org/10.1016/j.radphyschem.2022.110298

The characterization of bremsstrahlung and -rays from fuel debris differs from that of spent fuels evaluated to date, due to factors such as material composition and release of volatile fission products. In this work, in order to clarify the conditions under which the effect of bremsstrahlung compared to the total photons (bremsstrahlung and -rays) in fuel debris is maximized, the average energies and dose rates from the energy spectra of bremsstrahlung and -rays on the fuel debris surface were obtained using a Monte Carlo simulation. In the simulation, the average energies and dose rates were evaluated with consideration of the composition, size, fission product release, and retrieval time of the fuel debris. The simulation showed that the composition with the largest amount of change to the average total photons energy caused by bremsstrahlung was the molten fuel debris, and the composition with the maximum fraction of bremsstrahlung in the dose rate was the UO. The maximum value of the fraction of bremsstrahlung in the dose rate was evaluated to be about 17%. This work is expected to contribute to the prediction of the radiation characteristics of the fuel debris that will be retrieved from the Fukushima Daiichi Nuclear Power Station in the near future.

Calculation of air activation in an electron linac facility using the EGS4 code system

遠藤 章

JAERI-Tech 95-004, 19 Pages, 1995/02

JAERI-Tech-95-004.pdf:0.83MB

高エネルギー電子加速器施設では、電子ビームがターゲットに入射したとき発生する制動放射線による光核反応で、空気中の原子が放射化される。本研究では、電磁カスケードモンテカルロコードEGS4を用い、100MeV電子が銅ターゲットに入射したとき発生する制動放射線スペクトルを求め、空気中に生成されるN、C、Oの濃度を計算した。計算で得られた濃度は、実測値とファクター2以内で一致し、モンテカルロ法で得られる制動放射線スペクトルが、電子加速器施設における誘導放射能の評価に有効であるとが示された。