A SINGLE DETECTOR S SPECTROMETRIC PORTAL PECTROMETRIC MONITORING CONCEPT SOLVING THE PROBLEMS OF 'INNOCENT ALARMS'

摘要

In order to overcome the problems of ‘innocent alarms’ due to naturally occurringradioactive material (NORM) in vehicle monitoring and to medical isotopes in pedes- pedestrianmonitoring, a new techno trian technology has been developed in logy the last few years, based ongamma spectrometry. The US Domestic Nucl Nuclear Detection Office (DNDO) has startedear a new approach to dynamic primary screenin screening of vehicles, namely, advanced spectro- g spectrometricportals (ASPs) based on multiple NaI metric scintillation or HPGe detectors. Complexand expensive instruments with up to 14 larg large volume NaI or HPGe detectors have beene built and are presently being tested by DNDO DNDO. Up to now, it seems that these ASPs. cannot meet the goal of detecting HEU mask masked by NORM 95% of the time. Even if thised could be achieved, the approach is extremely expensive. The proposed new concept isbased on a single detector spectrometric portal monitor (SRPM) with one large NaIcrystal for dynamic primary screening of pede pedestrians, luggage, parcels, mail, etc., withstrians, immediate identification of innocent alarms. In addition, the SRPM can be used forsecondary screening of vehicles in static mode after an alar alarm is triggered by a conven- m conventionalplastic scintillator radiation portal mo tional monitor. After identifica nitor. identification by the SRPM, thetion radiation source can be quickly localized with a highly sensitive gamma or neutronsearch detector, faster and easier as compared to a conventional radioisotope identifierdevice. One SRPM can serve several primar primary vehicle lanes for se y secondary inspection.condary This makes it even more economic. The paper describes test result results obtained with a news SRPM, the SPIR IDENT, developed by SynOdys, France. Extensive testing, partly incooperation with the IAEA, indi indicates that this instrument ca cates can meet the requirements ofn the IAEA, the International Electrotechnic Electrotechnical Commission (IEC) al and the AmericanNational Standards Institute (ANSI) for dynami dynamic pedestrian monitoring as well as thec IEC and ANSI requirements for static vehicl vehicle monitoring in second e secondary screening withinary a few minutes.