1,720,998 research outputs found
Sensitivity tests and risk evaluation for steelworks portal systems
No full textFourteen portal systems installed at the entrance of as many iron scrap recycling plants have been tested. The systems which
underwent the test were supplied bythree manufacturers: Bicron, Eberline and Exploranium. For the tests, a truck trailer loaded
with iron scrap was equipped with guide tubes for the introduction of radioactive sources. During the whole experimental
campaign, the truck trailer was not modified, to assure test reproducibility. Analyzing the collected data, it was determined the
lowest exposure intensityin air from a 137Cs source still able to cause an alarm when, centered in the load, passes through
anyportal. On the basis of this value it follows a risk evaluation for a steelworks equipped (in agreement with the rules of
Lombardia region) with a portal at the entrance, area monitors for critical sites and gamma spectrometer for steel specimen.
© 2004 Elsevier Ltd. All rights reserved.
Keywords: Orphan sources; Portal system; Smelting accident
1. Introduction
Several reports (Lubenau and Yusko, 1998) on accidental
smelting of radioactive sources in furnaces confirm the possibilitythat
radioactive material might be mixed with scrap.
In Italysome accidents took place in the past; the major
are here listed (Risica and Neccetelli, 2000):
• 1990 137Cs contamination of an aluminium refineryin
two facilities and the relevant waste dump;
• 1991 137Cs contamination of an unauthorized dump of
wastes from aluminium melting;
• 1991 241Am contamination of some copper alloymanufacturer
and melting firms;
• 1993 137Cs contamination of a part of the Brescia and
Montirone goods yard;
∗ Corresponding author. Tel.: +39-223996366; fax: +39-
223996309.
E-mail address: [email protected] (F. Campi).
1350-4487/$ - see front matter © 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.radmeas.2004.05.007
• 1995 137Cs contamination of dust from settled fumes in
a steel mill in the decommissioning phase;
• 1997 137Cs and 60Co contamination of the Alfa Acciai
steel mill;
• 1998 137Cs contamination of the soil in a scrap storage
depot.
The most severe accident was that happened at Alfa Acciai
steel mill, in which 7 GBq of 60Co and 150 GBq of 137Cs
were molten in furnace. The consequences of the accident
were rather limited. Indeed, part of the final product was
contaminated byCo-60, but the dust abatement plant had
been effective in avoiding release of 137Cs in the surrounding
environment. Nevertheless, the total cost of the accident
was more than 25 million Euros, including the decontamination
of the plant and the missed profits.
After this accident, the Lombardia Regional Council issued
an Ordinance (Regione Lombardia, 1997) to impose
different radiometric surveys on metal scrap to be recycled.
A first monitoring must be performed on the scrap container
at the entrance of the steel mill. The Ordinance does
not specifywha
Cranioplastica e Radioprotezione: valutazione, mediante uno studio sperimentale, della dose di raggi X assorbiti da un paziente sottoposto a ricostruzione cranica
No full text
Sistema per la determinazione del contenuto di C14 nel moderatore di reattore gas grafite tramite produzione e campionamentodi Co2 in "situ"
No full textIl sistema consente la misura in situ di C-14 su grafite nucleare mediante genrazione di arco al plasma con successivo intrappolamento su drecsel a saturazione di soda caustica
Modellizzazione e simulazione di un rivelatore HPGe e del campione in configurazione Marinelli per l’ottenimento di curve d’efficienza tramite codice FLUKA
No full textAn atmospheric dispersion codes comparison applied to incineration of urban solid waste containing high activity radioactive sources
No full textIncineration of urban solid waste, accidentally contaminated by orphan sources or radioactive material, represents a potential risk for environment and public health. Moreover, production and emission of radioactive smoke plumes can determine a heavy contamination of the plant, leading to important economic damage. In order to prevent these hazards, in February 2004 a radiometric portal to detect radioactive material in incoming garbage trucks was installed at AMSA “Silla 2” urban solid waste incineration plant of Milan.
In this paper the dose committed to population and the environmental effects, due to incineration of a high activity source in absence of the radiometric portal, have been evaluated. Furthermore, results provided by the easy-to-use software Hotspot, specifically designed to supply a fast and simple tool for radioactive atmospheric releases evaluation, have been compared with the results provided by the more complex code Calpuff, the EPA reference code for atmospheric dispersion.
A 3,7 1010 Bq (1 Ci) source of 137Cs has been considered as reference. The maximum total dose committed to a single individual, due to inhalation and cloud submersion, appears to be negligible [less than 10-8 Sv]; nevertheless a light environmental contamination would involve a large area, leading to a significant exposure due to ingestion of contaminated foods.
Hotspot and Calpuff have been compared varying the most important meteorological conditions, mainly stability class and wind speed. Considering the high uncertainties affecting atmospheric dispersion calculation, the agreement between the two codes appears to be fine, although in low wind conditions [i.e. lower than 1 m s-1] relevant differences arise up to one order of magnitude.
Moreover Hotspot results are strongly influenced by some input variables such ad deposition velocity and scavenging coefficient. These parameters show a large variability depending on the physical-chemical form of the considered radioisotope. Exact determination of these values is neither fast nor easy and default values are frequently inadequate. Uncertainties due to improper values of these parameters can be much greater than uncertainties due to the atmospheric dispersion modelling. Therefore this aspect of the easy-to-use software Hotspot arises to be critical
Processo ed apparecchiatura per il prelievo di campioni da elementi di grafite per la determinazione del 14C
No full textAttuazione del piano di intervento prefettizio per le sorgenti orfane presso un impianto termovalorizzatore
Full text linkATTUAZIONE DEL PIANO DI INTERVENTO PREFETTIZIO PER LE SORGENTI ORFANE PRESSO UN IMPIANTO TERMOVALORIZZATORE
Autori: Fabrizio Campi, Alessandro Porta
Politecnico di Milano, Dipartimento di Energia - CESNEF ,
via La Masa, 34 - 20156 Milano
[email protected]
ABSTRACT
Il Decreto Legislativo n. 52 del 2007, all’art.14 comma 1, prevede che il Prefetto predisponga schemi di piano d’intervento tipo per la messa in sicurezza in caso di rinvenimento o di sospetto di presenza di sorgenti orfane nel territorio della provincia, avvalendosi del Comando dei Vigili del Fuoco, dell’Agenzia Regionale per la Protezione dell’Ambiente, dell’Azienda Sanitaria Locale e, se del caso, della Direzione Provinciale del Lavoro.
Di conseguenza nel 2008 il Prefetto di Milano, come quelli di altre province, ha emanato un proprio piano di intervento, nello spirito della legge citata.
Tale piano prevede che in caso di ritrovamento possano essere detentori di sorgenti orfane anche quegli impianti che, pur in assenza di uno specifico obbligo di legge, effettuano il controllo radiometrico del materiale in ingresso (ad esempio impianti di trattamento dei rifiuti urbani, termovalorizzatori, etc.) e che tali soggetti dovrebbero disporre di un esperto qualificato e di procedure di intervento per la gestione dei ritrovamenti.
Poiché l’attivazione del piano di intervento può essere provocata, tra le altre situazioni, anche da rinvenimento di sorgenti orfane durante un controllo radiometrico nei carichi in ingresso, le Aziende nelle quali sono operativi sistemi per la rilevazione della radioattività nei materiali dovranno dotarsi preventivamente di procedure di emergenza e di gestione degli allarmi diversificate in funzione del rischio. Infine il Prefetto dà come indicazione che tali protocolli siano concordati con VVF, ARPA e ASL, in quanto devono prevedere, nei casi in cui non si possa escludere un pericolo per la pubblica e privata incolumità, l’attivazione immediata dei citati Enti.
In questo contesto si è reso necessario applicare il Piano Prefettizio anche all’impianto Termovalorizzatore Silla 2 dell’Azienda A2A sito in Milano, che rientra nell’elenco delle aziende che effettuano controlli radiometrici sui carichi in ingresso. Ciò ha comportato la redazione di opportune procedure, con ripercussioni anche sulle strutture del sito. Nel lavoro sono illustrate le procedure adottate e gli adeguamenti strutturali messi in atto nell’ impianto
Calibration verification by Monte-Carlo simulations of a total gamma counting tunnel for clearance purposes
No full textThe Joint Research Centre of Ispra is one of the research centres belonging to the European Commission, and was created in the late '50s, in order to steer European research on nuclear industry. It currently hosts numerous nuclear facilities, some of which are maintained in operation, while others were shutdown in the past years or are currently being decommissioned.
The license for the waste station includes clearance for historical and post operations solid materials. As a license requirement for clearance, measurement and characterization of the material must be performed to verify that the radioactive concentration is below the established threshold levels given by the Italian Nuclear Safety Authority.
The final survey on the potentially clearable material homogeneous lots is performed through a commercial total gamma counting tunnel composed by eight plastic scintillators. Calibration is obtained by a standard container through a set of calibration measurements. A verification, via Monte Carlo simulations, of the measurement method of the gamma counting tunnel has been performed in order to have complete reliability on the system used for verifying the radioactive activity in the potentially clearable materials
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