Environmental Behavior and Biological Conversion of Tritium -Preriminary Release Experiment of Heavy water in a Greenhouse-

氚的环境行为和生物转化-温室重水预释放实验-

• 批准号: 07308038
• 负责人: ICHIMASA Michiko
• 金额: $ 9.02万
• 依托单位: IBARAKI UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07308038/
• 关键词: Tritium; Tritiated water; Environmental behavior; Deuterium; Heavy water; D_2O release experiment

Tritium is released from nuclear facilities into the environment during ordinary operation or by an accident. Tritium toxicity is markedly different depending on its chemical form in the environment, such as tritiated water (HTO), molecular tritium and organically bound tritium, and HTO is 25,000 times much radiotoxic than molecular tritium. Therefore, from a health physics view point, studies on tritium behavior in the environment are necessary for an accurate dose assessment, that is, actual HT oxidation in the environment, transfer of HTO to soil and environmental organisms and OBT formation and tritium elimination. However, field experiments on environmental behavior of tritium is difficult to do due to the public acceptance problem although such information under various local environmental conditions is needed to assess an accidental or chronic release of tritium. Thus heavy water (D_2O) vapor release experiments into a plastic greenhouse put on a field at Mito site of Ibaraki University were undertaken in November 1995 and August 1996, using D_2O as a substitute for HTO.The following studies were conducted : uptake kinetics of D_2O into leaves of vegetation including rice, Komatsuna, radish and so on, D_2O concentration ratios in edible vegetation to air moisture under steady-state, OBD formation in vegetation, deuterium elimination under the natural condition after D_2O release and effects of rainfall on deuterium elimination from vegetation, transfer of D_2O in water and aquatic organisms, deposition of D_2O into soil and its reemission, and formation of molecular deuterium and deuteriated methane.

氚在正常运行或事故中从核设施释放到环境中。氚的毒性因其在环境中的化学形态而有显著差异，如氚化水（HTO）、分子氚和有机结合氚，而HTO的放射毒性是分子氚的25，000倍。因此，从健康物理学的角度来看，研究氚在环境中的行为，即HT在环境中的实际氧化，HTO向土壤和环境生物的转移以及OBT的形成和氚的消除是准确的剂量评估所必需的。然而，现场实验的环境行为的氚是很难做到的，由于公众接受的问题，虽然这样的信息在各种当地环境条件下，需要评估一个偶然的或长期的释放氚。因此，1995年11月和1996年8月在茨木大学水户基地的一个塑料温室中进行了重水（D_2O）蒸气释放实验，使用D_2O作为HTO的替代物。水稻、小松菜、萝卜等植物叶片吸收D_2O的动力学，植物中D_2O浓度与空气湿度的稳态比值、植物中OBD的形成、D_2O释放后在自然条件下的氘消除以及降雨对植物中氘消除的影响、D_2O在水体和水生生物中的迁移、D_2O在土壤中的沉积和再释放，分子氘和氘代甲烷的形成。

项目成果

S.Yokoyama,H.Noguchi et al.: "Reemission of Heavy Water Deposited on a Soil Surface to the Atmosphere." Journal of Fusion Engineering and Design. (in press). (1997)

S.Yokoyama，H.Noguchi 等人：“土壤表面沉积的重水重新排放到大气中”。

M.Saito.: "Blood tritium level as a conservative estimate of soft tissue dose after tritium injection in mice." Health Physics. (in press).

M.Saito.：“血液氚水平是对小鼠注射氚后软组织剂量的保守估计。”

H. Amano, et al.: "Formation of organically bound tritium in plants during the 1994 chronic HT release experiment at Chalk River" Fusion Technology. 28. 803-808 (1995)

H. Amano 等人：“1994 年乔克河长期高温释放实验期间植物中有机结合氚的形成”融合技术。

S. Yokoyama, H. Noguchi, et al.: "Reemission of Heavy Deposited on a Soil Surface to the Atmosphere." Journal of Fusion Enginerering and Design. (in press).

S. Yokoyama、H. Noguchi 等人：“土壤表面沉积的重质物质重新排放到大气中”。

P. A. Davis, et al.: "Overview of the 1994 Chronic HT Release Experiment at Chalk River" Fusion Technology. 28. 840-845 (1995)

P. A. Davis 等人：“1994 年 Chalk River 慢性 HT 释放实验概述”融合技术。