Knowledge Bank

The Oak Ridge National Laboratory is engaged in research programs concerned with the spectrophotometric study of aqueous solutions at elevated temperatures and pressures. In March 1960, the Applied Physics Corporation of Monrovia, California, was awarded a subcontract for the design and development of a high-temperature, high-pressure spectrophotometer system based on the Cary Model 14 Automatic Recording Spectrophotometer (ultraviolet, visible, and near-infrared regions) insofar as possible, and consistent with the Laboratory's specifications. The system is designed for operation at temperatures from 25 to at least $350\circ C$ and at pressures up to 5000 psi. The cells, which have a variable optical path length from 1 to 20 cm, are of a pressurized-annulus, cell-within-a-cell, type. They are designed with provisions for adding gas pressure in addition to the water vapor pressure present at temperatures up to the maximum anticipated and to withstand a pressure of 10,000 psi at $350\circ C$. With this system, it should be possible to carry out spectral measurements essentially up to the critical point of water $(372\circ C)$ in water and deuterium oxide systems. A cell of the type to be used in this system has been recently constructed and tested with complete success. The design details for the entire complex system, including all drawings, have been completed. It is anticipated that the construction of the facility will be finished in time for the installation and testing of the system at ORNL by the end of 1962. The system has also been designed for use with solutions which are very high in alpha radioactivity for spectrophotometric work with the transuranic elements. A brief review will be presented of the entire system and several important features of the design will be discussed in detail. Several cell designs have been studied and techniques have been investigated for cleaning the windows, removing bubbles, and viewing the cell contents at operating conditions. An auxiliary, variable, slit-system has also been designed to permit measurements on optically dense and multiple phase systems. A circulating fluid jacket heating system has been designed for the cells, and a cell rocking mechanism is provided to permit mixing and equilibration of the cell contents between, and within, the liquid and gaseous phases. The type of work to be carried out with the high-temperature, high-pressure spectrophotometer will be discussed, and other related work and equipment development will be presented insofar as time will permit.