Federal emergency management agency fema rep-2, rev. 2 / June 1990
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- 4.6Other Measurement Considerations
- 4.7Cost Considerations
4.5Survey Team DeploymentPortable, hand-held instrumentation as described for the above monitoring methods can best be deployed by monitoring teams in motorized vehicles. These teams should be directed to drive through the projected path of the airborne plume along appropriate routes and to take measurements at locations that can be identified from preselected reference points. The reference points for identifying measurement locations should be easily recognized places such as buildings, cross roads, street intersections, bridges, etc.l At the completion of the monitoring at each location and at the completion of the survey, the team will report the measurements obtained to the EOC where they can be plotted on a map of the area. The actual location of the plume and the concentrations of noble gases, radioiodines and airborne radioactive particulates within the plume will be determined, as will the projected radioiodine dose. These data should be compared against the projected exposure rate pattern, and appropriate adjustments should be made, keeping in mind that it is not unrealistic for the projected exposure rates to differ by a factor of a 100 or more from the measured exposure rates. Data from the facility, if available, should be factored into these projected exposure rate patterns whenever facility emergency plans include dispatching emergency monitoring teams. The number of monitoring locations in a given area should be a function of the distance from the facility, the topography of the area, the density of population, and the presence of roads. All monitoring measurements should be made at approximately the same time and as quickly as possible. Therefore all monitoring teams should be deployed at approximately the same time and the length of time required for each team to cover its assigned survey route should also be similar. The frequency with which the plume should be surveyed is a function of the stability or consistency of the release and the local meteorology as well as the radioactivity concentrations and the number of people which may potentially be exposed. A more complete discussion of team deployment and the necessary logistics for such an operation are covered in Sections 6.5, 6.6, and 6.7 of this guidance. 4.6Other Measurement ConsiderationsThe FRPCC Subcommittee considered the concept of making field measurements of the distribution of radionuclide concentrations in the plume with a system of fixed monitoring locations as a method of estimating the dispersal of the plume and for projecting exposure patterns. This concept was rejected because of the large number of sophisticated detectors and the telemetry necessary for such a system. At least 150 detector locations would be required out to a distance of approximately 8 miles from the site for good spatial distribution.li Both radioiodine and direct gamma measurements would have to be made and telemeter to the EOC in order to get the necessary information for making a dose projection. The maintenance, repair and calibration of such systems would be very costly and hard to justify in view of the accident probability. The deployment of instrumentation to make environmental measurements is partially dictated by the degree of instrument portability. For example, if the only instrumentation available for a specific measurement is a stationary system, such as a gamma spectrometer with a power source but without telemetry, then deployment must include periodic inspections to read out this system. Even if telemetry to the EOC is available, the system would probably require periodic servicing (i.e., changing filters, supplying gasoline, etc.). Conversely, if a choice of instrumentation exists, then the choice is influenced by the preferred deployment. For example, in choosing between stationary, mobile, or portable instrumentation, the desire for flexibility in choosing the measurement pattern should require the selection of portable instrumentation. 4.7Cost ConsiderationsAn important consideration for an emergency radiation monitoring plan is to minimize the cost because the probability for a nuclear accident large enough to produce significant offsite consequences at a specific facility is considered extremely small.lii Further, for an actual accident, backup equipment will be available. The cost can be subdivided into three major categories: 1) the initial investment in equipment, 2) the cost of maintaining the equipment, and 3) the cost of training and retraining personnel. The State should minimize its investment in equipment that is operated solely for accident monitoring. However, that equipment purchased should be reliable. This will reduce maintenance costs. Instrumentation from other activities such as civil defense should be used where possible. The developer of State emergency radiation monitoring plans should first determine the deployment of available stationary instrumentation around the facility that may satisfy the requirements for a time history of measurements at selected spots in the measurement pattern. The facility itself may have a number of offsite measuring systems, normally used for environmental monitoring purposes, which also have an emergency measurement capability. The State planner should then ascertain the portable instrumentation that is available from local units for use by survey teams in a more flexible measurement pattern. Available resources in the locality should be compared to the total resources needed for the State plan. Additional instruments may be made available through the Federal government as described in Appendix D. The State should acquire the remaining instrumentation needed to complement these resources. Portable instrumentation is expected to be the most cost-effective category of instrumentation for measuring exposure rate patterns from an airborne release from a nuclear accident. The plume from such a release may cover a large area and its shape may be continuously changing with the prevailing meteorology. Therefore, a flexible system using a limited number of measuring devices is much more cost effective than the large number of fixed detectors with their associated telemetry required to obtain the same information.liii
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