National Radioactivity Monitoring Network (LMR) Data Report 1993-1995
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Type
Report
Language
en
Date
1996-12-31
Research Projects
Organizational Units
Journal Issue
Title
National Radioactivity Monitoring Network (LMR) Data
Report 1993-1995
Translated Title
Landelijk Meetnet voor Radioactiviteit (LMR): Data
rapportage 1993-1995
Published in
Abstract
Voor de vroegtijdige signalering van grootschalige
nucleaire incidenten en het volgen van een eventuele radioactieve besmetting
is in maart 1990 het Landelijk Meetnet voor Radioactiviteit (LMR) in gebruik
genomen. Begin 1996 is het LMR, na integratie met een op de lokale
overheden afgestemd stralingsmeetnet ontwikkeld in opdracht van BiZa,
omgevormd tot het Nationaal Meetnet Radioactiviteit (NMR). Dit rapport
evalueert de werking van het LMR in de periode 1993-1995 en presenteert een
overzicht van de veldmetingen uit die jaren. In dit rapport wordt de
werking van de twee typen veldmonitoren, de Bitt RS02/RM10E stralingsmonitor
en de FAG FHT59S luchtstofmonitor, nader gespecificeerd. Meetgegevens van
het omgevingsdosisequivalenttempo zoals bepaald door de Bitt monitor,
bevatten een systematische fout. Hiervoor wordt een correctieformule
gepresenteerd. De door de luchtstofmonitor gemeten totale
alfa-activiteitsconcentratie is, onder niet-ongevals-omstandigheden,
rechtevenredig met de evenwichts-equivalente concentratie van kortlevende
vervalproducten van 222Rn, EEDC. In de periode 1993-1995 vonden er in of in
de buurt van Nederland geen radiologische incidenten van enige betekenis
plaats. Wel zijn in die periode enkele tientallen automatische
waarschuwingsmeldingen gegenereerd. In een enkel geval betrof het een reele
overschrijding van een in het LMR gehanteerde waarschuwingsdrempel, door
natuurlijke oorzaak of door industrieel handelen. De meeste meldingen
hadden echter een (meet)technische oorzaak, en waren vals. In 1994, maar
vooral in 1995 was het aandeel valse meldingen groot, deels vanwege
veroudering van de meetapparatuur en deels vanwege extreme
weersomstandigheden in 1995. Desondanks was de beschikbaarheid van LMR-data
in de periode 1993-1995 (stralingsdata circa 96%, luchtactiviteitsdata circa
91%) hoger dan in voorgaande jaren. De LMR meetgegevens hebben het inzicht
vergroot in de variaties die optreden in de natuurlijke
stralingsachtergrond, en de parameters die hierbij een rol spelen. Dit
rapport bevat een literatuurverwijzing naar de resultaten van een
uitgebreide LMR data-analyse.
In March 1990, the Dutch National Radioactivity Monitoring network (LMR) was put into operation. The tasks were early detection of major nuclear incidents and collection of radiation data during such an event. By integrating with a network more directed at the requirements of local authorities, the LMR was succeeded by the National Monitoring Network Radioactivity (NMR) early in 1996. This report evaluates the performance of the LMR over the years 1993-1995 and presents a data review over this period. The technical properties are described of the two field monitors used, the Bitt Technology RS02/RM10E proportional counter device and the FAG FHT59S airborne gross-alpha/beta-activity monitor. Measurements of external radiation, expressed in ambient dose-equivalent rate contain a systematic error for the correction of which a conversion formula is presented. The natural alpha-activity concentration as determined by the aerosol monitor is (during non-emergency situations) proportional to the equilibrium-equivalent decay product concentration of 222Rn progeny in air, EEDC. In the period 1993-1995 nuclear accidents with any impact for the Netherlands did not occur. However, automatic warning messages indicating that radiological data were recorded above one of the warning levels were received many times. Some of these warnings were due to natural causes or industrial activities, but most were false, for instance, because of malfunctioning equipment. In 1994, but especially in 1995 the number of 'false' messages was relatively large, partly due to the ageing of the instruments and partly due to the extreme weather conditions of 1995. Nevertheless, the availability of LMR data in the period 1993-1995 was higher than in previous years: dose-rate on average some 96%, air activity approximately 91%. The monitoring results of the LMR have increased the knowledge of the variations in the natural background radiation and the determining parameters. This report contains a reference to the results of an extended LMR data analysis.
In March 1990, the Dutch National Radioactivity Monitoring network (LMR) was put into operation. The tasks were early detection of major nuclear incidents and collection of radiation data during such an event. By integrating with a network more directed at the requirements of local authorities, the LMR was succeeded by the National Monitoring Network Radioactivity (NMR) early in 1996. This report evaluates the performance of the LMR over the years 1993-1995 and presents a data review over this period. The technical properties are described of the two field monitors used, the Bitt Technology RS02/RM10E proportional counter device and the FAG FHT59S airborne gross-alpha/beta-activity monitor. Measurements of external radiation, expressed in ambient dose-equivalent rate contain a systematic error for the correction of which a conversion formula is presented. The natural alpha-activity concentration as determined by the aerosol monitor is (during non-emergency situations) proportional to the equilibrium-equivalent decay product concentration of 222Rn progeny in air, EEDC. In the period 1993-1995 nuclear accidents with any impact for the Netherlands did not occur. However, automatic warning messages indicating that radiological data were recorded above one of the warning levels were received many times. Some of these warnings were due to natural causes or industrial activities, but most were false, for instance, because of malfunctioning equipment. In 1994, but especially in 1995 the number of 'false' messages was relatively large, partly due to the ageing of the instruments and partly due to the extreme weather conditions of 1995. Nevertheless, the availability of LMR data in the period 1993-1995 was higher than in previous years: dose-rate on average some 96%, air activity approximately 91%. The monitoring results of the LMR have increased the knowledge of the variations in the natural background radiation and the determining parameters. This report contains a reference to the results of an extended LMR data analysis.
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