DWD) I N the Framework of Nuclear Emergency Response Programmes

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Surveillance of Radioactivity in the Atmosphere by the Deutscher Wetterdienst (DWD) i n the Framework of Nuclear Emergency Response Programmes

T.Steinkopff, A.Dalheimer, W.Dyck, B.Fay, H.Glaab, I.Jacobsen Deutscher Wetterdienst, Frankfurter Strasse 135, 63067 Offenbach, Germany

SUMMARY The Deutscher Wetterdienst (DWD), German Meteorological Service, is charged with the surveillance of radioactivity in the atmosphere as a part of the emergency information network of the „Integrated Measureme nt and Information System“(IMIS) in Germany. The results of measurements of radioactivity and the meteorolog ical products are transferred regularly to this network. The DWD is also integrated into the Environmental Emer geny Response Programme (EER) of the World Meteorological Organization (WMO) as a communication hub. The computer infrastructure, the operational experience in data management as well as the national and internati onal communication systems in operation are significant arguments to run the early alert system on the surveillan ce of atmospheric radioactivity at the national meteorological service.

INTRODUCTION In 1955 the Deutscher Wetterdienst (DWD), German Meteorological Service, was integrated into the national nuclear emergency response programme concerning the surveillance of radioactivity in the atmosphere. Stimulated mainly by the experiences of the nuclear accident of Chernobyl the existing national response mecha nisms and international cooperation have been substantially revised. Especially, the Environmental Emergency R esponse (EER) programme of the World Meteorological Organization (WMO) has been developed to provide me teorological dispersion prognosis to the International Atomic Energy Agency (IAEA). The integration of meteor ological services into this EER programme is an important object which includes the harmonisation of the differe nt specific national arrangements with the relevant international arrangements.

In Germany emergency response programmes in general and especially the surveillance of radioactivit y in the environment are strictly separated according to the responsibilities of federal agencies and state authoriti es given by law. The emissions of nuclear power plants (NPP) are controlled by the state governments, which are responsible for the nuclear emergency response programmes in the vicinity of NPPs. The emissions are measure d online by the staff of the NPP and the controlling governmental state laboratories. Corresponding to a mandato ry procedure for measurements samples of the environment (air, precipitation, ground, grass, milk) in the vicinity of the NPP are measured periodically (1). The results are published quarterly.

Since 1955 the DWD is in charge of monitoring air and precipita tion to determine radioactive substan ces. As a result of the operational con tinuous measurements, figure 1 show s the total beta-activity in precipitatio n as an average of all measuring DW D stations from 1957 to 1998. There are three significant maxima due to th e nuclear tests of the USA and the fo rmer Soviet Union in the late fiftees a nd the early sixtees and due to the co nsequences of the accident of Cherno byl in 1986. After the nuclear test ban treaty had been signed by nearly all governments in 1963, no tests in the a tmosphere were performed. As a resu lt, the radioactivity in air and precipit Figure 1.Total beta-activity in precipitation as an average of all ation decreased. Higher concentration measuring stations of DWD from 1957 to 1998 s of radioactivity in the precipitation i n 1976/77 and 1980/81 were significantly measured and reported as a result of the nuclear tests in the atmospher e by the Peoples Republic of China (2).

The diminishing political interest towards the necessity of the surveillance of radioactivity in the envir onment has been immediately stopped after the accident of Chernobyl on April 26, 1986. The environmental mo

1 P-11-296 nitoring facilities on both, federal and state level, proved to be well prepared for the situation which occured in t he Federal Republic of Germany following the nuclear accident at the Chernobyl nuclear power plant. However a lot of problems came up facing the different national and international recommendations with regard to thresho ld values of radioactivity. The speed of the transboundary transport of hazardous material and its impact within a distance of more than 2000 km illustrates the large scale influence of the accident. Because of the experiences in the Chernobyl accident, in Germany a new law was adopted in 1986. The Precautionary Radiation Protection Ac t [StrVG] concerns an area of legislation which was not covered by the Atomic Energy Act [AtG], and the Radia tion Protection Ordinance [StrlSchV] which generally regulates the handling of radioactive material. The new la w`s intention was to protect the population in case of a national nuclear emergency.

THE ROLE OF THE DWD IN THE GERMAN „INTEGRATED MEASUREMENT AND IN FOR-MATION SYSTEM“(IMIS) As a consequence of the new act the national "Integrated Measuring and Information System for the Monitoring of Radioactivity in the Environment" (IMIS) was established on the basis of a computer network (3, 4). All relevant data of the environment and recommendations towards radiation protection are summarised at th e Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) in order to inform the p ublic (figure 2). Within IMIS the early detection of radioactivity in the air and the measurement of radioactivity c oncentrations are of main importance for the radiological prognosis with the calculation model "Programme Syst em for the Assessment and Mitigation of Radiological Consequences" (PARK) run by the Federal Office for Rad iation Protection (BfS). Trajectories and dispersion calculations are important instruments for the early activation of countermeasures and the information of all governmental laboratories charged with the surveillance of radioa ctivity. A set of general administrative regulations which contain the regulations for the generation, transmission, compilation, evaluation, and documentation of data within the framework of IMIS have been issued. Within this set of regulations, attention is directed to two guidelines, the content of which is formed by the routine measurin g programme and the intensive measuring programme. In the case of a nuclear event intensified measurements ar e initiated. The extention of the measuring network of DWD and the development of dispersion calculations base d on the Lagrangian particle dispersion model (LPDM) were parts of the new concept.

gamma dose rate measurements of gaseous I-131 radionuclides in the atmosphere accumulation measurements BfS DWD and of radionuclides evaluation in the North and BSH the Baltic seas

accumulation and evaluation accumulation and accumulation of measuring results, measurements evaluation and meteorological products of radionuclides evaluation DWD in federal IAR BfG waterways

measurements of accumulation and evaluation of data environmental presentation by specialised institutes samples by the 16 Federal States BfS

BMU: Federal Ministry for the Environment, Nature and Nuclear Safety BfG: Federal Institute of Hydrology, Koblenz Federal Ministry for the BSH: Federal Maritime and Hydrography Environment, Nature and Office, Hamburg Nuclear Safety DWD: German Meteorological Service, BMU Offenbach IAR: Institute for Atmospheric Research, Freiburg IMIS: Integrated Measuring and Information System

Figure 2.Integration of the DWD in the "Integrated Measurement and Information System for the Monitoring of Radioactivity in the Environment (IMIS)"

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The measuring network of DWD fo r radioactivity in the atmosphere consists of 4 0 homogeneously distributed measuring statio ns, each measuring station integrated into the building of a weather station so that the instru ments are under permanent control of the staf f. The density of the network is a consequence of the requirements for the large scale covera ge of the territory of Germany and the require ments for the early detection of radioactive m aterial emitted by foreign sources near the bor der. The special measuring programme of DW D is summarized by table 1. Each station is equipped with a nuc lide specific measuring step-feed-filter system continuously surveying the radioactivity in ai r by gamma-ray spectrometry to guarantee the early detection of artificial radionuclides. An example of the daily report of results is demo nstrated in figure 3. Only results for the natura l aerosol bound radioactivity could be detecte d at this date. Simultaneously, the aerosol bou nd artificial alpha- and beta-activity are calcul ated by instruments based on discriminating c alculation methods: alpha-beta-pseudo-coincidence-diff erence (ABPD), alpha-energy-range-discrimi nation (AERD).

Based on the technical infrastructu Figure 3.Example of the IMIS presentation for the daily re (communication and data processing) of D results of 214Pb and 137Cs (limits of detection) WD the data from the measuring stations are measured by the γ-ray-step-feed filter system regularly transmitted to the Central Office at (limits of detection for 137Cs illustrated by stars) Offenbach at least daily, in case of an emerge ncy every two hours. The data from the measuring stations and the results of the radiochemical laboratory are tra nsferred to the computer network IMIS immediately after having been controlled (5,6).

Table 1: Sampling and measuring programme of the DWD in the normal mode Environmental measurement measuring method sampling-/measuring limit of detection samples interval aerosols, 39 γ−ray emitters γ-ray-step-feed filter-s daily 10 mBq/m3 ystem aerosols, 40 γ−ray emitters γ−ray spectrometry weekly 0.005 mBq/m3 aerosols, 40 artificial alpha ABPD, AERD daily 30 mBq/m3 activity aerosols, 40 artificial beta a ABPD, AERD daily 50 mBq/m3 ctivity aerosols, 40 90Sr, 89Sr beta-counter monthly 0.001 mBq/m3 aerosols, 8 235U, 239Pu α−ray spectrometry monthly 0.0002 mBq/m3 gaseous iodine, 20 γ−ray emitters γ−ray spectrometry weekly 1 mBq/m3 precipitation, 40 γ−ray emitters γ−ray spectrometry monthly 2 mBq/ l precipitation, 8 90Sr, 89Sr beta-counter monthly 1 mBq/l precipitation, 8 235U, 239Pu α−ray spectrometry monthly 0.03 mBq/l precipitation, 8 Tritium liquid scintillation monthly 1 Bq/l counter precipitation, 40 β−activity beta-counter daily 20 mBq/l ground, 38 γ−ray emitters in-situ-γ−ray spectrom every month 1h 150 Bq/m2 etry

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Depending on the t ype of accident, radioactive p lumes may be expected in gre at heights up to the tropopaus e. For this reason aircraft mea surements are necessary as a supplement to ground based measurements especially whe n no information is available on the source of the radioacti ve release and details of the a ccident. The objectives of aer ial measurements are the loca Figure 4. Sampling system for airborne measurements lisation of the radioactive clo ud, the gamma-dose-measure ment of the radioactive cloud in its horizontal and vertical extension, the sampling of aerosols and the gamma-ra y spectrometry of filter and cloud water aboard. The result of a recently developed sampling system is presented in figure 4. The data are transmitted to the central computer at Offenbach. The dispersion calculations will be ess entially improved by these radiological and these meteorological data (7).

TRAJECTORIES AND DISPERSION CALCULATIONS The operational calculation of trajectories facilitates a preliminary estimation of the translocation of c ontaminated air parcels. The Lagrangian particle dispersion model (LPDM) simulates the processes of transport and diffusion as well as the dry and wet deposition by computing about 100000 random walk particle trajectories representing parcels of material released from the source (8,9,10,11,12,14,15). The concentrations are determine d by counting those particles in atmospheric boxes. The deposition is calculated through the loss of mass for thos e particles which have contact with precipitation or touch the ground and through the subsequent accumulation o f this mass on the ground.

As a matter of routine, backward trajectories are calculated twice daily at 0 UTC and at 12 UTC for al l radioactivity monitoring stations and forward trajectories for most of the European NPPs. Based on a high resol ution forecast model (Local Model, LM) forward trajectories are additionally calculated for all German, Czech, Swiss and some French nuclear power plants. Dispersion calculations are carried out for four nuclides agreed, na mely 95Zr, 131I, 132Te and 137Cs. The meteorological data are available in a grid with a horizontal mesh width of ap prox. 55 km provided by the new global model (GME). Based on the LM forecast data of a horizontal mesh widt h of 7 km are available for Germany and its surrounding countries.

The emergency system proper is menu-operated and designed to be run by the meteorologist on duty a ny time. Tables and plots are automatically produced. The trajectory positions and the radioactivity concentration fields are directly transferred into the computer network of IMIS. The results are stored in the IMIS database fro m where the data are retrieved together with the radioactivity measurements as input to the programme package PARK.

PRODUCTS OF THE WEATHER RADAR SYSTEM To judge the meteorological behaviour of contaminated air masses, the information of the radar netwo rk combined with the results of high resolution forecast models are useful tools in the early hours after a nuclear accident. With the help of 16 weather radar systems integrated into a radar network it is possible to achieve some qualitative information of the location and the intensity of precipitation areas in near real-time with overall cove rage of Germany. With the currently used scan strategy local radar images are generated every 15 minutes at all o perational radar sites. Superposition of these local radar site images leads to composite radar products which rev eal the survey of the present situation of precipitation in Germany (PC-composite product) and -by additional use of radar images of neighboring National Meteorological Services- in Central Europe (PI-composite product), res pectively. The spatial resolution is 4 km x 4 km. The German national composite image includes 920 km x 920 k m and the international composite product covers 1440 km x 1440 km. Further in a quantitative sense, more prec ise estimation of the precipitation totals at certain locations requires a calibration with ground-based precipitation values. A method for on line calibration of radar precipitation values with ground-based rain gauge measuremen ts is currently under development at the DWD.

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INTERNATIONAL NU CLEAR EMERGENCY Fax Fax RESPONSE ARRANG EU IAEA RSMC National Contact Point Toulouse, Bracknell EMENTS Only the dispersio n calculation provides first in Fax formation for the prognosis o

Fax f the radiological situation. T his is of great importance fac ing international arrangement s and national decisions. The National Contact Point WMO, DWD NMS DWD and the German Minis BMU Fax try of Environment are both DWD products parts of the structures embed ded in international arrangem I M I S ents with the IAEA (figure 5). To assist countries that do n ot have adequate emergency preparedness capabilities the BMU: Federal Minstry for the Environment, IAEA has several different pr Nature Conservation and Nuclear Safety GTS DWD: German Meteorological Service ogrammes. In the unlikely ev EU: European Union ent of a major nuclear accide GTS: Global Telecommunication System IAEA: International Atomic Energy Agency nt with transboundary conseq IMIS: Integrated Measuring and Information uence the Early Notification System Convention will provide pro NMS: National Meteorogical Service RSMC: Regional Specialized Meteorological Centre mpt warning to affected coun WMO: World Meteorology Organisation tries whilst the Assistance Co nvention will ensure that rele vant help will be provided by dispersion of alert distribution of dispersion products of DWD information calculations by RSMCs measuring data, non-affected countries. trajectories, etc. A special Environ- mental Emergency Response programme (EER) has been established to meet the interests of IAEA and to take advantage of the capabilities o f the WMO. Special meteorological services are supposed to calculate dispersion programmes in case of a nuclea r emergency. These so called Regional Specialized Meteorological Centres (RSMC) are Bracknell (U.K.), Melbo urne (Australia), Montreal Figure 5. Integration of DWD in Nuclear Emergency Response Programmes (Canada), Moskau (Russia), Peking (China), Tokio (Japa n), Toulouse (France) and Washington (USA). The DWD plays a key role in the distribution of an alert informati on of IAEA via the Global Telecommunication System (GTS) as a technical communication contact of the WM O. The different communication lines between national bodies, international bodies and meteorological institutio ns are outlined in figure 5. In case of a nuclear emergency the DWD will be informed by either IAEA or by BM U or the press media so that an internal emergency programme will be initiated. Information by IAEA about a nu clear accident has to be distributed by means of GTS so that all National Meteorological Services (NMSs) and th e RSMCs are informed. The RSMCs will undertake the calculation and the distribution of dispersion results to I AEA and to the NMSs, if demanded. The dispersion model output of RSMCs will be sent by telefax to the nation al contact points. Simultaneously, the DWD will also calculate trajectories and the dispersion of the concentratio n in air as well as the deposition as demanded of the national ministry. These products will be distributed to the n ational contact point and other national bodies via the computer net of IMIS. Furthermore, all the products of D WD (meteorological products and results of measurements) will also be distributed to other national contact poin ts of the European Union (EU) by the BMU.

The European Commission supports a system for the rapid exchange of information "ECURIE" (Euro pean Community Urgent Radiological Information Exchange System) and a network for mutual assistance with r egard to specialized radiological protection needs. ECURIE was established as a result of a 1987 Council Decisi on and effectively extends the scope within the EU of the IAEA Convention of Rapid Notification. The Europea n Union Data Exchange Platform (EURDEP) seeks to avoid a duplication of data by creating software for extract ing selected information from any given national database and translating it into a common format (13). Such a d irect incorporation in a master data base is implemented at the Joint Research Centre in Ispra (Italy). At the prese nt time some 20 countries participate in this data exchange exercise, which is based on daily values of gamma do

5 P-11-296 se rates and air concentrations.

OPERATIONAL PERFORMANCE OF NUCLEAR EMERGENCY RESPONSE ARRANG E-MENTS To ensure operational preparedness in case of emergencies, tests and exercises have been agreed withi n the framework of the national and international arrangements (e.g., IMIS, EU, OECD/NEA, WMO/IAEA). Fa cing the international arrangements, different communication lines among national bodies, international bodies, a nd meteorological institutions have been set up and are tested in an exercise scheme. The DWD participates in th ese to a varying degree. Focus is on the national concept of radioactivity monitoring and the prediction in the fra me of IMIS, and the integration into the EER programme of the WMO.

The European Tracer Experimen t (ETEX) in 1994 (14) aimed at the establis hment of a data base for the validation of m odels predicting the transport, dispersion an d deposition of radioactive substances in th e case of nuclear accidents and at an assessment of the capability of national/internatio nal functions in providing results under real -time operational conditions. From the resu lts of the first experiment ETEX-1 it could be concluded that all participating institutio ns were capable of meeting the required res ponse time of 6 hours after notification in p roviding the relevant products including the ir transmission. The products of DWD succ eeded in predicting the arrived time at the v arious measuring points in Europe with an accuracy of 3-6 hours, which is considered sufficient given a release point 1000 km dis tant. In the ATMES-II-report (15) the perfo Figure 6. Backward trajectories rmance of dispersion models regarding the experiment was evaluated. The DWD model took the first rank of 49 participating models from 25 countries. Th e second experiment ETEX-2, however, also showed the numerous problems still left due to a more complex me teorological situation.

In summer 1998 concentrations of 137Cs with 0.01-2.5 mBq/m3 –as results of 7d-samples- were measu red by numerous European institutes engaged in measuring radioactive traces. The backward trajectories provide d initial information about the possible source (figure 6). After the source was known -an emission of approxima tely 1012 Bq 137Cs by a steel producing company in Algeciras/Spain- dispersion prognoses were calculated based on the archived meteorological data. The observed concentrations of 0.01-2.5 mBq/m3 were in good agreement with the results of the dispersion calculations and gave proof of the quality of the calculation (figure 7).

Finally, a Real-time On Line Decision Support System (RODOS) for off-site emergency arrangement is being developed with support from the Commissions Nuclear Fission Safety Research and Development Progr amme. The main objective is to develop a system that is comprehensive and suited for broad application across E urope. About 40 institutes from some 18 European countries are contributing to the further development of the s ystem. The main benefits of developing and implementing RODOS are a better use of European resources for im proving off-site emergency management, a common platform for including the best features of existing and/or fu ture national systems, a basis for improved communication between countries and for exchange of monitoring da ta, a more consistent support to decision makers due to comprehensiveness of the system, a greater transparency in the decision process and, most importantly a more coherent and harmonized response to any future accident th at may affect Europe (16, 17).

The RODOS system can provide decision support at four distinct levels

• acquisition and checking of radiological data and their presentation • the analysis and prediction of the current and future radiological situation • the simulation and potential countermeasures, in particular, determination of their feasibility and quantificat

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ion of their benefits • evaluation and ranking of alternative countermeasures strategies by balancing their respective benefits and disadvantages.

In Germany, the installation of the computersystem RODOS at a central place is intended in the near f uture. The RODOS system is already installed in several countries for research and development and /or operatio nal use.

The technical infrastructure of the DWD enables the management of measurements at the weather stat ions, the evaluation of data by trained staff, and the transfer of data to other offices or to the public in a very shor t time. The provision of results of the radiological measurements and the results of dispersion prognoses requires a high degree of reliability of the communication lines. The international communication system of the WMO al lows a very fast transfer of information because of the continuously operated lines. Therefore, the installation of measuring systems at locations of meteorological services demonstrates the advantages of representative samplin g locations as well as of the availibility of technical infrastructure and a well trained staff.

Figure 7. Result of a dispersion calculation, time integrated surface concentration

REFERENCES

1. „Richtlinie zur Emissions- und Immissionsüberwachung kerntechnischer Anlagen“ (REI). Gemeinsame s Ministerialblatt Nr.29 vom 19.08.1993, S.502 ff (1993). 2. W. Kiesewetter Die Radioaktivitätsüberwachung der Niederschläge und ihre Bedeutung. Fachgespräch - Überwachung der Umweltradioaktivität, Praxis der Überwachung der allgemeinen Umw eltradioaktivität, München, 10.-12. März 1981, 101-121 (1981). 3. A.Bayer, D.Noßke, J.Burkhardt, A.Löbke-Reinl, M.Werner Messen, Auswerten und Bewerten im Integrierten Mess- und Informationssystem für die Überwachung d er Umweltradioaktivität (IMIS). Strahlenschutz für Mensch und Umwelt, 25 Jahre Fachverband für Stra hlenschutz, Aachen, Fortschritte im Strahlenschutz, FS-91-55-T, 194-199 (1991). 4. A.Bayer The Integrated Measuring and Information System for the Monitoring of Radioactivity in the Environme

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nt (IMIS): Tasks, Aims, and Components.in: 2nd Expert Symposium on the „Integrated Measuring and In formation System (IMIS) for the Monitoring of Environmental Radioactivity", The Federal Minister for the Environment, Nature Conservation, and Nuclear Safety(Editor): Federal Office for Radiation Protect ion, Berlin, (1992). 5. T.Steinkopff, B.Fay, H.Glaab, I.Jacobsen, W.Kiesewetter Großräumige Überwachung der Radioaktivität in der Atmosphäre durch den Deutschen Wetterdienst. U mweltradioaktivität, Radioökologie, Strahlenwirkung; 25.Jahrestagung des Fachverbands für Strahlensc hutz e.V., Binz auf Rügen, Fortschritte im Strahlenschutz, FS-93-67-T, 167-172 (1993). 6. Th.Steinkopff, B.Fay, H.Glaab, I.Jacobsen, W.Kiesewetter The Surveillance of Radioactivity in the Atmosphere by the Deutscher Wetterdienst. Proceedings of the S econd International Meeting on Low-level Air Radioactivity Monitoring, Madralin 14 - 18 February 199 4, Warsaw, 29-34 (1995). 7. W.Dyck, H.Brust, E.Müller Airborne Measurement of Radioactivity. Environmental Impact of Nuclear Installations, Proceedings of the Joint Seminary from September 15th to 18th 1992 at the University of Fribourg/Switzerland ) (1993). 8. B.Fay, H.Glaab, I.Jacobsen Modelle des Deutschen Wetterdienstes für die Ausbreitungsprognose. 9.Fachgespräch zur Überwachung der Radioaktivität, München-Neuherberg 25. bis 27.04.1995, 441-456 (1995). 9. B.Fay, H.Glaab, I.Jacobsen, R.Schrodin Evaluation of Eulearian and Lagrangian Atmospheric Transport Models at the Deutscher Wetterdienst using ANATEX Surface Tracer Data. Atmos.Environment, Vol.29, No.18, 2485-2497 (1995). 10. Quarterly Report of the Operational NWP-Models of the Deutscher Wetterdienst. Deutscher Wetterdien st, Offenbach, Januar 1995. 11. B.Fay, H.Glaab, I.Jacobsen, R.Schrodin Radioactive Dispersion Modelling and Emergency Response System at the German Weather Service. Po llution Modelling and its Application X, Herausg. S.-E. Gryning and M.M.Millan, NATO-Challenges of Modern Society Vol.18, Plenum Press, New York and London, 395-403 (1994). 12. EUR 17346 - ETEX Symposium on Long-Range Atmospheric Transport, Model Verification and Emerge ncy Respons, Proceedings, K.Nodop(editor) Vienna(Austria), 13 - 16 May 1997, Challenges of Modern Society Vol.18, Plenum Press, New York and London, 395-403 (1994). 13. EURDEP (European Union Radiological Data Exchange Platform, Reference Manual and European A utomatic Monitoring System. Marc DeCourt and Gerhard de Vries eds., Joint Research Centre, Europea n Commission, EUR 16415 (1996). 14. H.Glaab, B.Fay, I.Jacobsen Evaluation of the Emergency Dispersion Model at the Deutscher Wetterdienst using ETEX Data, Atmos. Environment, Vol.32, No.24, 4359 – 4366 (1998). 15. S.Mosca, R.Biancani, R.Bellasio, G.Graziani, W.Klug ATMES-II-Evaluation of long-range Dispersion Models using data of the 1st ETEX realease. European Commission, Official Publication of the European Communities, EUR 17756 EN, Luxembourg (1998). 16. RODOS, Mid-term Report of the RODOS Project. J.Ehrhardt and A.Weiss eds., RODOS R-4-1998, Fors chungszentrum Karlsruhe, FZKA 6203, (1998). K.Burkart 17. Tasks of Emergency Response.,Grenzüberschreitender Notfallschutz, Publication Series Progress in Rad iation Protection, A. Bayer, J. Lombard, D. Rauber eds., TÜV-Verlag, Köln, (1999).