James P. Burelbach博士，Elizabeth J. Raines和Martin G. Plys，SCD，Fauske＆Associates，LLC
INTRODUCTION
在化学过程中，台式尺寸的热危害测试是一种有效的方法，可以快速收集关键安全数据以进行过程扩大和变更管理。
These accepted test methods are directly relevant to the packaging, transport, and storage of radioactive waste that is or can become chemically reactive.
For chemically reactive waste streams it is vital to identify safe temperature and pressure conditions and to quantify adiabatic heat and gas generation rates in order prevent or accommodate thermal instability within the waste package or storage facility.
有机硝酸盐实验(ARSST)
High level waste streams can include organic-bearing sludge and salt cake waste. Organic complexants like sodium acetate along with oxidizers like sodium nitrate present the potential for spontaneous runaway chemical reactions (thermal instability).
以下数据是在1°C/min加热的模拟氧化剂混合物中的20.5％乙酸钠（6％的有机碳或TOC）。这些数据显示在200°C下的显着放热活性，在300°C下“点火”。
Ammonium nitrate is another common oxidizer that has been involved in large scale industrial disasters and is potentially explosive when mixed with organic fuel. The data below illustrate the effect of a small amount of organic contamination (polyethylene scrap).
ADIABATIC CALORIMETRY TOOLS
VSP2™ (Vent Sizing Package 2)
- Up to 100 ml sample size
- 不锈钢，螺丝钉或玻璃衬里的测试单元
- 压力平衡
- Closed cell testing gives direct vapor pressure
- Strong mixing suitable for two-phase or slurries
- 适合污染研究的规模
- 缩放适合测试剂量或采样
- Test setup takes about 2 hrs
COMMON FEATURES
- Test solids or liquids (magnetic stirring)
- 轻量级测试单元à低热惯性
- 测试细胞热容量<<样品热容量
- “ phi-factor”接近统一〜1.05至1.1
- Evolved heat is not lost to the container (or the environment) but increases the sample temperature
共同的好处
- Data are directly scalable
- 测量绝热温度升高（ATR）
- Measure temperature rise rate dT/dt = f(T)
- Measure pressure rise rate dP/dt = f(T)
- Infer molar gas generation rate
- Kinetic modeling
常见的应用程序
- 紧急排气尺寸（缓解压力）
- Safe storage temperature
- 安全包装/容器尺寸
- 最高率（TMR）的时间
- Temperature of no return (TNR)
- 自加工分解温度（SADT）
ARSST™（高级反应性系统筛选工具）
- Up to 10 ml sample size
- 缩放适合热筛选（识别能量反应）
- 通常打开细胞测试
- Scale suitable for large rates of gas generation (decomposition)
- Scale suitable for operation in a glove box or hot cell
- Test setup takes about 20 min
“红油”实验（VSP2）
用浓缩硝酸饱和（HNO3）饱和的三丁基磷酸（TBP）可以在溶剂提取系统蒸发器和水箱中形成两层有机/水性形态。有机相反应于放热，在某些条件下可能导致热失控
(e.g. Tomsk-7 reprocessing plant explosion in Russia, 1993).
结论
有机硝酸盐实验
- 氧化剂（例如硝酸钠或硝酸铵）中的有机污染会导致Arrhenius失控反应，然后是波浪状“繁殖反应”
- 热危害测试可以识别反应传播所需的最小TOC，并且观察到的动力学为安全包装和存储提供了技术基础
红油实验
Two separate exotherms were observed
- The 1st exotherm at 80 °C is mild (< 1 °C/min)
- Tempering (under atmospheric pressure) occurs at about 100 °C due to evaporation of dissolved water
- The 2nd exotherm (two peaks) is stronger (< 10 °C/min)
- 对于较低的HNO3浓度或在存在分解产物（例如丁基丁酸）的情况下，峰值速率降低了，但活化能（从DT/DT斜率推断）是不变的
- 在“封闭电池”配置中（例如，如果过程容器通风孔被关闭或堵塞）不会发生，并且压力构建
- Closed cell self-heat rates increase exponentially to 1000 °C/min
- The Tomsk-7 accident can be explained by a combination of weak tempering and insufficient venting capacity
REFERENCES
Burelbach, J. P., & Theis, A. E. (2005). “Thermal Hazards Evaluation using the ARSST,” 3rd Intl. Symposium On Runaway Reactions, Pressure Relief Design, and Effluent Handling, Cincinnati.
Epstein, M., et al. (2008). “Thermal Stability and Safe Venting of the Tri-n-Butyl Phosphate-Nitric Acid-Water (‘Red Oil’) System—II: Experimental Data on Reaction Self-Heat Rates and Gas Production and their Correlation,” Vol. 163, Nuclear Technology, Aug.Ibid, “III: Predictions of Thermal Stability Boundaries and Required Vent Size.”
