Estimation and control of beryllium-7 behavior in liquid lithium loop of IFMIF

• Published in: Fusion engineering and design Vol. 82; no. 15; pp. 2490 - 2496
• Main Authors: Ida, Mizuho, Nakamura, Hiroo, Sugimoto, Masayoshi
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2007; New York, NY Elsevier Science
• Subjects: Applied sciences; Beryllium-7; Controled nuclear fusion plants; Devices using thermal energy; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Heat exchangers (included heat transformers, condensers, cooling towers); IFMIF; Installations for energy generation and conversion: thermal and electrical energy; Liquid lithium; QAD-CGGP2R; Worker dose; Worker dose; IFMIF; Liquid lithium; Beryllium-7; QAD-CGGP2R; Shield; Solubility; Radiation source; Lithium; Shielding; Dose equivalent; Maintenance; Dose rate; Temperature gradient; Nuclear fusion reactor; Deuteron; Heat exchanger; Beryllium; Radioactive source; Deposition
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2007.07.014

In the IFMIF liquid lithium target system, beryllium-7 ( 7Be) produced by deuteron–lithium (D–Li) reaction is the dominant radioactive nuclide at maintenance of the lithium loop components, since the dose equivalent rate of the 7Be is several orders of magnitude larger than that due to other nuclides. Behavior of 7Be, such as solubility and deposition in the liquid lithium was estimated considering temperature gradient in the loop. The result showed that all most all 7Be, 5.02 × 10 15 Bq, would be deposited on most downstream part of the heat exchanger with the lowest temperature among the main flow. Subsequent estimation for dose equivalent rate due to this localized radioactive source showed that, without radiation shielding, the rate would be 8.5 × 10 7 μSv/h, about seven orders of magnitude higher than a guideline of 10 μSv/h for yearly working time of 2000 h. Required thickness of radiation shield made of lead was found to be 8 cm.