Year
1992
Abstract
Throughout the nuclear complex, the demand for measurements of nuclear materials holdup is increasing. Plant-wide campaigns to quantify holdup in ventilation ducts and holdup measurements in support of duct remediation are in progress at most DOE sites. Plans to satisfy more stringent requirements for holdup measurements are being developed. Facility decommissioning that accompanies downsizing the complex will require extensive holdup measurement efforts. In the early phases of planning for the modern complex, holdup measurements for new facilities are being specified at the facility design stage. Beyond the DOE, international inspection activities are relying, increasingly, on holdup measurements for verification. Developments in nondestructive assay technologies in the past decade have provided some support for measurements of this type. The user's requirements of ruggedness and reliability have been satisfied with compact gamma-ray detectors and spectroscopy instrumentation, but improvements are still needed in simplicity, portability, and speed. Current portable spectroscopy instruments require user sophistication as well as more than one person for transport between measurement locations. However, it is becoming clear that the real measurement need is the simultaneous operation of dozens of units, each by a single relatively unsophisticated user, to perform thousands of measurements per inventory period. The rapid and reliable conversion of measurement data to holdup quantities is essential. A new, miniature modular m_ultic.hannel analyzer (MMMCA) is being designed to meet facility holdup measurement needs. The palm-size, processor-based modular unit includes self-contained battery power, a lowresolution amplifier, high-voltage power, an analog-to- digital converter, and nonvolatile memory to automatically set up hardware and specify conditions for data acquisition. During supervisory setup, checkout, and calibration of the assay system, the MMMCA is connected to a PC by serial port. The PC program provides a display of the spectrum and a user-friendly interface to the typical multichannel analyzer features. The program is used to set the parameters for the desired MMMCA measurement conditions and hardware settings. To achieve the required simplicity and portability in routine operation for holdup measurements, we replaced the PC with a pocket-size, programmable, controller/data-logger unit that automates the acquisition and storage of data and accepts identification and measurement-geometry input from the user by its keypad or by measurement-location bar codes. This particular controller unit is also used to transport the stored user input, reduced data, and location bar codes for hundreds of holdup measurements to a PC database manager that is utilized by a software program to calculate holdup masses.