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Yoshida, Kazuo; Hiyama, Mina*; Tamaki, Hitoshi
JAEA-Research 2024-007, 24 Pages, 2024/08
JAEA-Research-2024-007.pdf:2.1MB
An accident of evaporation to dryness by boiling of high-level radioactive liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (Ru) are released from the tanks with water and nitric-acid mixed vapor into the atmosphere. Accurate quantitative estimation of released Ru is one of the important issues for risk assessment of those facilities. It has been observed experimentally that volatility of RuO
is suppressed by HNO
generated by HNO
radiolysis. The analysis of chemical reactions of NO
including HNO and HNO in the waste tank is essential to simulate of these phenomena. To resolve this issue, an analytical approach has been attempted to couple dynamically two computer codes SHAWED and SCHERN. The simulation of boiling behavior in the tank is conducted with SHAWED. SCHERN simulates chemical behaviors of HNO, HNO and NO in the tank. A programmatic coupling algorithm and a trial simulation of the accident are presented in this report.
Yoshida, Kazuo; Tamaki, Hitoshi; Hiyama, Mina*
JAEA-Research 2023-001, 26 Pages, 2023/05
JAEA-Research-2023-001.pdf:1.61MB
An accident of evaporation to dryness by boiling of high-level radioactive liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (Ru) are released from the tanks with water and nitric-acid mixed vapor into the atmosphere. Accurate quantitative estimation of released Ru is one of the important issues for risk assessment of those facilities. To resolve this issue, an analytical approach has been developed using computer simulation programs to assess the radioactive source term from those facilities. The proposed approach consists analyses with three computer programs. At first, the simulation of boiling behavior in the HLLW tank is conducted with SHAWED code. Next step, the thermal-hydraulic behavior in the facility building is simulated with MELCOR code based on the results at the first step simulation such as flowed out mixed steam flow rate, temperature and volatilized Ru from the tank. The final analysis step is carried out for estimating amount of released radioactive materials with SCHERN computer code which simulates chemical behaviors of nitric acid, nitrogen oxide and Ru based on the condition also simulated MELCOR. Series of sample simulations of the accident at a hypothetical typical facility are presented with the data transfer between those codes in this report.
Do, V. K.; Yamamoto, Masahiko; Taguchi, Shigeo; Takamura, Yuzuru*; Surugaya, Naoki; Kuno, Takehiko
Talanta, 183, p.283 - 289, 2018/06
Times Cited Count：11 Percentile：38.24(Chemistry, Analytical)We develop a novel analytical method employing liquid electrode plasma optical emission spectrometry for measurement of total cesium in highly active liquid wastes. Limit of detection and limit of quantification are 0.005 mg/L and 0.02 mg/L, respectively. The method is validated and applied to the real samples.
