APPENDIX XIV:EXAMPLE OF OFF-SITE RADIOLOGICAL DATA IN DIFFERENT FORMATS FIG.XIV-1. Example of off-site radiological data in graphical format.
Dose rate (µSv/h) vs time Reference 6:30 6:35 6:40 6:45 6:50 6:55 7:00 7:05 7:10 7:15 7:20 7:25 7:30 Zone 1 0.1 0.1 0.1 0.2 0.2 0.1 0.2 0.2 0.1 0.1 0.2 0.1 0.1 Zone 2 0.1 0.2 0.1 0.1 0.2 0.2 0.2 0.1 0.1 0.3 0.2 0.1 0.2 Zone 3 0.3 0.2 0.1 0.1 0.2 0.1 0.2 0.2 0.1 0.1 0.2 0.3 0.2 Pole 46 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Pole 49 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Pole 51 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Pole 58 0.1 0.1 0.2 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Pole 63 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Pole 100 0.2 0.2 0.1 0.2 0.3 0.2 0.1 0.2 0.2 0.1 0.1 0.2 0.1 Pole 101 0.2 0.2 0.1 0.2 0.1 0.2 0.2 0.1 0.2 0.1 0.3 0.2 0.1 Pole 102 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Pole 103 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.1 0.1 0.1 0.1 0.2 0.1 Pole 104 0.2 0.2 0.1 0.2 0.1 0.2 0.2 0.2 0.1 0.1 0.2 0.2 0.1 Pole 105 0.2 0.1 0.2 0.2 0.3 0.2 0.2 0.1 0.2 0.1 0.2 0.1 0.1 Pole 106 0.2 0.1 0.2 0.2 0.2 0.1 0.1 0.2 0.2 0.2 0.2 0.1 0.2 Pole 107 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Pole 108 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 South Musquash 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1
TABLE XIV-1, EXAMPLE OF OFF-SITE RADIOLOGICAL DATA IN MATRIX FORMAT
FIG.XIV-2. Dose rate measurements during passage of cloud.
Methods of providing radiological field data
Using tables to represent the plume
A spreadsheet tool is developed to provide readings along the centre line at various distances as a function of time. This is dependent on the release profile, i.e. readings vary according to plume travel and the release fraction in the time interval considered. To do this, the release can be divided in several time intervals, each with an assumed release fraction of the total release. The doses were scaled according to that release fraction. The dose rates can be obtained by dividing the dose by the time interval, and introducing a time correction factor that accounts for plume travel time at the given wind speed.
A map showing the plume centre line is used to indicate the plume travel path. In this example, a Gaussian dispersion model can be used to generate integrated dose results and plume location. This map shows the plume centre line and the lateral extent of the plume, where it is assumed, in this case, that the values are 10% of the plume centre line values. This is arbitrary. Between the plume centre line and the 10% line, the readings are assumed to vary linearly.
The controller must choose the data from the table at the right distance and time. If the survey is off the centre line, the controller introduces a “fudge” factor to reduce the value of the reading in the table.
Conversely, data can be tabulated at fixed points and pre-calculated to take into account the distance off the centre line. This is effective especially when procedures call for surveys at pre-established monitoring locations, or when fixed monitors are used.
A similar table of locations and times can also be used to shown the simulated readings in the facility or at the emergency site.
The disadvantage of this method is that it is difficult to model variations in wind direction, and hot spots. The main advantage is that only one map is required for all data types (e.g. dose rate, air samples). One table is used for each data type. Remember to tabulate the data values as they would be read off the appropriate instrument (e.g. cpm or mSv/h).
Using graphs to represent the plume
Survey data can be conveyed through pictures of zones within which selected readings would be obtained if surveyed. Several pictures can be used to account for time variations. A separate set of pictures is required for each data type, including for example plume dose rates, ground shine, air contamination, surface contamination, etc.
Surface contamination
There are two basic methods of providing the exercise participants with off-site surface contamination data needed for input purposes.
In the simpler method, controllers provide the radiological survey teams with gamma or beta-gamma dose rates or other relevant radiological readings at each survey point. The controller concerned will usually be stationed with the survey team or at the location from which the surveyors are dispatched. Similarly, dosimeters, samples of water, vegetation, etc.
sent to environmental assessment laboratories are assigned pre-calculated readings which are divulged by a controller at the laboratory, preferably after the actual sample analysis has been completed. Alternatively, an appropriate delay could be included to take into account the time taken to dispatch the sample to the laboratory, the workload at the laboratory and the estimated counting and analysis time. This method suffers from the minor disadvantage that the laboratory staff are not fully exercised, although this is largely overcome if some work in sample preparation and analysis is carried out.
The second method, which entails considerably more work, involves the preparation of sources and samples containing radioactive material in appropriate amounts which will give predetermined readings on field survey instruments or in the environmental assessment laboratory. Generally speaking, laboratory staff may be adequately exercised in handling radioactive samples during routine operations or spills, so that the complication of introducing radioactive samples into large exercises may be unnecessary. This may not, however, provide staff with experience in handling large numbers of active samples or dealing with the inherent problem of sample segregation to prevent cross-contamination. However, environmental survey laboratories are dependent upon their ability to maintain low background levels of radiation, and it may not be prudent, as part of an exercise, to introduce large quantities of highly radioactive samples into this type of laboratory, with the concomitant potential for contamination and increased levels of background radiation. Field survey teams can also be adequately drilled using spiked samples in a classroom setting, although it may be desirable to see how they and their instruments perform in adverse weather conditions.
These two basic methods may be combined by allowing survey teams and laboratories to perform measurements on samples that may or may not be radioactive and then substituting appropriate values based on the scenario's detailed event description. The use of pre-irradiated dosimeters to simulate received radiation doses should also be considered, as these can easily be prepared in advance of the exercise.
APPENDIX XV: EXAMPLE OF EXERCISE SOFTWARE TO SIMULATE FIELD