Hydroxylamine nitrate (HAN), an important agent for the nuclear industry and the U.S. Army, has been involved in several costly incidents. To prevent similar incidents, the study of HAN safe storage and handling boundary has become extremely important for industries. However, HAN decomposition involves complicated reaction pathways due to its autocatalytic behavior and therefore presents a challenge for definition of safe boundaries of HAN storage and handling. This research focused on HAN decomposition behavior under various conditions and proposed isothermal aging testing and kinetic-based simulation to determine safety boundaries for HAN storage and handling. Specifically, HAN decomposition in the presence of glass, titanium, stainless steel with titanium, or stainless steel was examined in an Automatic Pressure Tracking Adiabatic Calorimeter (APTAC). n-th order kinetics was used for initial reaction rate estimation. Because stainless steel is a commonly used material for HAN containers, isothermal aging tests were conducted in a stainless steel cell to determine the maximum safe storage time of HAN. Moreover, by changing thermal inertia, data for HAN decomposition in the stainless steel cell were examined and the experimental results were simulated by the Thermal Safety Software package. This work offers useful guidance for industries that manufacture, handle, and store HAN. The experimental data acquired not only can help with aspects of process safety design, including emergency relief systems, process control, and process equipment selection, but also is a useful reference for the associated theoretical study of autocatalytic decomposition behavior.

Hazard communication is an essential part of a comprehensive safety plan, especially for those facilities that contain reactive chemicals. There are a variety of means of communicating a chemical hazard, but one of the most prevalent in the United States is the Instability Rating found in the NFPA 704 standard. While the NFPA 704 identifies hazards associated with exothermically decomposing compounds, it neglects compounds that decompose endothermicly to form large quantities of gas. Such compounds have been known to cause accidents due to pressure buildup, such as in the BP Amoco Polymers explosion in 2001. In this work, twenty-five compounds were examined via an APTAC to determine their pressure and temperature profiles. These profiles were then used to determine the amount of gas generated, the gas generation rate, the gas generation product, the onset temperature, and the instantaneous power density. These properties were analyzed to determine those that best represented the instability hazard of the chemical. Ultimately, the molar gas generation rate and onset temperature were chosen to rate the selected chemicals, and new cut-offs were established to divide the chemicals into revised instability groupings. Compounds that did not decompose in the temperature range examined were given the rating of zero. Compounds with low onset temperatures and high gas generation rates were assigned the rating of 4, while chemicals with high T_onset and low dn/dt_maxn were assigned a value of 1. Chemicals with high onset temperatures and high gas generation rates were grouped into rating 3. Group 2 included low onset temperature compounds with low gas generation rates. The cut-offs used to define these regions were 130 degrees C for the onset temperature and 0.01 (1/min) for the gas generation rate. The ratings were found to be comparable to the current NFPA system, but improved upon it by providing a valid rating (group 1) for the chemicals that endothermically generated gas. Detailed plots of the data are provided as well as suggestions for future work.