Model za određivanje operativnih intervencijskih razina u sustavu nuklearne pripravnosti

scientific master's theses

• Title (english): Operational intervention level model for nuclear emergency preparedness
• Author: Saša Medaković
• Mentor: Nenad Debrecin (mentor)
• Committee member: Nikola Čavlina (predsjednik povjerenstva)
• Committee member: Nenad Debrecin (član povjerenstva)
• Committee member: Gordana Marović (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2003, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering; Power Engineering
• Universal decimal classification (UDC): 621 - Mechanical engineering. Nuclear technology. Machinery

Abstract

U projektiranju, izgradnji i pogonu nuklearnih postrojenja poduzimaju se različite radnje kojima je cilj reduciranje rizika pojave nuklearne nesreće. Mala vjerojatnost pojave sekvenci događaja koje bi dovele do ispuštanja većih količina radioaktivnih tvari u okoliš ipak postoji. Takve sekvence događaja nazivamo nuklearne nesreće. U svrhu umanjivanja posljedica nuklearnih nesreća uspostavljaju se sustavi nuklearne pripravnosti. U slučaju nuklearne nesreće slijed događaja je izrazito brz. Odluke o poduzimanju mjera moraju biti donesene u vrlo kratkom roku, a istovremeno moraju biti opravdane. Zbog toga je razvijen pristup odlučivanja o poduzimanju mjera zaštite i spašavanja koji se temelji na intervencijskim razinama. Intervencijske razine su unaprijed definirane granične vrijednosti radijacijskih doza. Primjena pojedine mjere zaštite i spašavanja smatra se opravdanom samo ukoliko se procjenjuje da je moguće izbjeći veću dozu od one propisane intervencijskom razinom. Intervencijske razine iskazuju se u obliku doza koje je moguće izbjeći poduzimanjem pojedine mjere zaštite i spašavanja. One se u pravilu ne mogu izravno mjeriti te se zbog toga definiraju operativne intervencijske razine (OIL). OIL-i se izvode iz intervencijskih razina i skupa dodatnih pretpostavki i izravno su usporedivi s rezultatima mjerenja na terenu. U okviru ovog magistarskog rada izrađen je analitički model za određivanje OIL-a za izlaganje radioaktivnom oblaku. Mjere zaštite koje se primjenjuju u tom slučaju su zaklanjanje, evakuacija i jodna profilaksa. Svrha izrade ovog modela jest uvođenje vremenske ovisnosti u izračun predefiniranih vrijednosti OIL-a za hitne mjere zaštite i spašavanja. Također, ovim se modelom omogućuje i razlikovanje navedenih OIL-a u ovisnosti o vrsti nesreće. Poseban naglasak prilikom izrade modela postavljen je na utvrđivanje vremenske ovisnosti omjera brzine ukupne efektivne doze i brzine ambijentalne doze (faktor R). Pri određivanju OIL-a uvažene su vrijednosti intervencijskih razina propisane hrvatskim zakonodavstvom. Rezultati analize načinjene pomoću modela ukazuju na to da vrsta nesreće i vremenska ovisnost faktora R bitno utječe na sva tri OIL-a za izlaganje radioaktivnom oblaku. Rezultat ovog rada je preporuka o korištenju predefiniranih vrijednosti OIL-a koje ovise o vrsti nesreće i o vremenu proteklom od obustave reaktora.

Abstract (english)

During the process of designing, construction and operation all necessary measures are undertaken to ensure safe operation of nuclear power plants. In spite of that, there is a slight possibility of uncontrolled radioactive release into the environment. Such event is called nuclear accident. The purpose of the development of nuclear emergency preparedness is to prevent or reduce nuclear accident consequences. In the case of nuclear accident the time sequence is extremely short. Because of that, all countermeasures have to be introduced at a short notice and have to be justified. To fulfill that task, a decisionmaking system based on intervention levels for taking countermeasures has been developed. Intervention level is the level of avertable dose at which a specific countermeasure or remedial action is taken in an emergency exposure situation or a chronic exposure situation. Since avertable doses can't be measured directly operational intervention levels (OIL) are defined. OILs are derived from intervention levels and a set of additional assumptions. They are directly comparable with results of on site measurements. In this master’s thesis a simple analytic model for calculation of OILs based on dose rates in a radioactive plum is developed and implemented. The model has two main purposes. The first is to determine time-dependence of predefined OILs for early phase countermeasures. The second is to analyze these OILs according to type of nuclear accident. The main focus in model development was put on ratio of total dose rate to ambient dose rate (factor R). Results of the analysis have shown that types of nuclear accident and timedependence of factor R influence all three OIL for early countermeasures. Based on results of the analysis, a recommendation of this master’s thesis is to use more than one value of predefined OILs during the early phase of a nuclear accident. Values of OILs should be determined depending on nuclear accident type and the time passed since reactor was shut down.

• Keywords: nuklearna nesreća; operativna intervencijska razina; brzina doze; sustav nuklearne pripravnosti
• Keywords (english): nuclear accident; operational intervention level; dose rate; nuclear emergency preparedness
• Language: croatian
• URN:NBN: urn:nbn:hr:168:473060
• Study programme: Title: Postgraduate master programme in electrical engineering; Study programme type: university; Study level: postgraduate; Academic / professional title: Magistar znanosti elektrotehnike (Magistar znanosti elektrotehnike)
• Catalog URL: http://lib.fer.hr:8080/cgi-bin/koha/catalogue/detail.pl?biblionumber=29024
• Type of resource: Text
• Extent: 115 str. ; 30cm
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2019-05-24 13:05:28