OPERATIONAL RADIONUCLIDE CONTROL

The Reactor System, including the core and its support components, and portions of the the neutron control systems must perform, with a high degree of confidence, lOCFRlOO-related radionuclide control functions under design basis conditions. Since the seismically induced forces on these components from an QBE or an SSE could potentially affect the safe operation and safe shutdown of the reactor, the criteria and methods described below are aimed at providing assurance that these components can be adequately designed to assure their continued functionality during and after these events. 

An in-service test program will be developed that includes preservice (baseline) testing and a periodic inservice test program to insure that all "safety-related" valves will be in a state of operational readiness to perform their principal radionuclide control function throughout the life of the plant. The test program will be based on the ASME Boiler and Pressure Vessel Code, Section XI, Division 2, Subsection IGV (primarily IGV-1000). 

A fuel performance analysis was conducted to predict the core temperature distributions, fuel particle failure, and gaseous and metallic fission product release under normal operating conditions at full power. The calculated fission product releases were then compared with the radionuclide design criteria, summarized In Section 4.2.3 and presented In detail In Section 11.1 to determine the adequacy of the fuel and core designs with regard to the radionuclide control requirements. 

Modem pulse height analysers essentially contain dedicated digital computers which store and process data, as well as control the display and operation of the instrument. The computer will usually provide spectrum smoothing, peak search, peak identification, and peak integration routines. Peak identification may be made by reference to a spectrum library and radionuclide listing. Figure 10.15 summarizes such a pulse height analysis system. 

CORPEX Technologies, Inc., offers CORPEX technology for the decontamination of undesirable and toxic ions or radionuclides from contaminated surfaces and coatings. The vendor states that the process can operate as either a batch or semicontinuous process. The commercially available CORPEX technology uses patented, innovative chelation chemicals to control and recover radioactive and other types of hazardous metal ions from soils, concrete, steel, and other materials. 

Early, T. O. Jacobs, G. K. Drewes, D. R. "Geochemical Controls on Radionuclide Releases from a Nuclear Waste Repository in Basalt Estimated Solubilities for Selected Elements RHO-BW-ST-39, Rockwell Hanford Operations, Richland, Washington, 1982. 

Analyte half-lives need to be considered to arrange for rapid collection, transfer to the laboratory, and radioanalytical chemistry processing before they decay to poorly-detectable low amounts. Types of emitted radiation control the detector that must be purchased, calibrated, and operated. Radiochemists and radiation-detector operators who commonly handle a specific category of radionuclides become skilled in purifying and counting these radionuclides. 

Because of the unique operational and safety requirements of radiopharmaceutical synthesis, the motivation for the development of automated systems is clear. These unique constraints include short synthesis times and control from behind bulky shielding structures that make both access to and visibility of radiochemical processes and equipment difficult. The need for automated systems is particularly expressed for PET radiopharmaceutical synthesis, with the short-lived radionuclides emitting high-energy y photons at 511 keV. Automated synthesis systems require no direct human participation. The short half-lives of the PET radionuclides may require repeated synthesis during the day, thus being a potential radiation burden for the operator when not using automated systems. 

The module operation efficiency is determined on the one hand, by selectivity of membrane elements and sorption characteristics of ion-exchangers and on the other hand, by physico-chemical and radionuclide composition, concentration of suspended particles, salts and radionuclide activity levels. The integral decontamination-purification coefficients Kpurj t, depending on LRW radionuclide, physical and chemical composition, vary within 10 - 10 . Depending on composition of initial LRW and in compliance with on-line control data, MMSF can operate either imder the full-cycle mode involving all basic modules or imder reduced-cycle mode using only some of modules. 

Since 1966 the basin has been operated as a closed system. The basin water is continuously recycled through a diatomaceous earth filter, and no contaminated water is released to ground. Makeup water is added to the basin by spraying casks as a part of the cask decontamination procedure. The water level is controlled by adding additional water to the basin if needed, or by purging a small stream from the basin to the plant waste evaporator. An increase in the concentration of radionuclides and dissolved solids in the water has occurred as a result of the recycle process. Consequently, a plant-scale ion-exchange unit was installed in July 1973, based on the results of laboratory studies, to remove radionuclides from the basin water. The fuel storage basin water at that time had the approximate chemical and radiochemical composition shown in Table I. 

CDC. 1994. Radionuclide releases to the atmosphere from Hanford operations, 1944-1972 Hanford environmental dose reconstruction project. Richland, WA Centers for Disease Control and Prevention. 

Air sampling equipment consists of a framework or housing, a sample collector, a collector holder, an air pump, and control and recording equipment, including a flow control device, flow-rate meter, timer, and data recording or transmitting system, as shown in Fig. 5.1 (see Sections 15.2. and 15.4 for examples). The system should provide structural support, shelter, and a tight connection for the collector. The air pump must provide the required airflow. The system must be maintained for continuous operation and proteeted from vandalism. The number and location of stations must be selected to provide the information for which they are operated, e.g., to detect and quantify airborne radionuclides that are released at a site or distributed across an area. 

Detector quality control records are reviewed to assure that control samples and the radiation background have been measured recently and that the detectors in use are within control limits (Section 11.2.10). Brief control source and background measurements are performed before the screening process begins to assure that detectors continue to operate appropriately and have not been contaminated recently. The detection limit in terms of activity per sample is calculated for all radionuclides of interest to determine whether a null result will meet radionuclide detection requirements for the submitted samples. 

The QA effort for radiation detection instruments is directed toward correct installation, accurate calibration, and stable operation. For correct installation, the instrument must be shown to function as designed by the manufacturer and specified by the purchaser. Accurate calibration depends on reliable radionuclide standards handled correctly. Stable operation is demonstrated by comparing control parameters such as the count rate for a stable radiation source and the detector radiation background measured at selected intervals. 

This system has been used inside a research aircraft where outside air is ported into the aircraft and through the system, as well as in an under-wing pod with direct frontal airflow, as seen in Fig. 15.2. The system continuously measures and records the concentration of airborne photon-emitting radionuclides. The R-TARAC stores all collected data and can be automatically or manually controlled from a remote console to provide instant datareporting to the flight crew and an operations center. 

First, the philosophy requires that control of radionuclides be accomplished with minimal reliance on active systems or operator actions. By minimizing. the need to rely on active systems or operator actions, the safety case centers on the behavior of the laws of physics and on the integrity of passive design features. Arguments need not center on an assessment of the reliability of pumps, valves and their associated services or on the probability of an operator taking various actions, given the associated uncertainties involved in such assessments. 

The Neutron Control Subsystem also has the functions of controlling direct exposure to operating personnel and of controlling transport of radionuclides during handling operations. 

Specific inventories of radionuclide activities for irradiated isotope production targets and associated radioactive waste are evaluated in Section 3.4 of this SAR. Administrative controls, including both HCF operations procedures and TSRs, are established based on these evaluations to accomplish processing operations safely. 

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