| Abstract | Rizik je definiran kao „učinak neizvjesnosti na ciljeve“ te tako predstavlja izrazito bitan faktor u donošenju odluka. Primjenom procjene rizika moguće je rizike identificirati, analizirati i evaluirati te na temelju toga donijeti odluke o njihovom tretiranju. Cilj ovog rada je tako procjena rizika kod primjene uređaja za servisnu inspekciju gravitacijskog nosača fuzijskog reaktora. U uvodnom dijelu rada definirani su bitni pojmovi poput tehničkog sustava, kvara i servisne inspekcije te je predstavljena firma INETEC čiji uređaj će se koristiti za potrebe ITER projekta. Drugi dio rada se sastoji od pregleda procjene rizika u obliku njezine povijesti i strukture, ali nekih od često korištenih metoda. Temeljem uputa od strane ITER organizacije, procjena rizika u ovome radu je provedena korištenjem RAMI metode koja se sastoji od IDEFØ funkcijske analize, FMECA analize te RBD analize. Treći dio rada se tako sastoji od opisa procesa RAMI metode kao i definiranja koncepata pouzdanosti, raspoloživosti, održivosti i ispitljivosti. Četvrti dio rada se sastoji od opisa uređaja na kojemu je provedena procjena rizika te same procjene rizika. Uređaj za ispitivanje se zove WP6 oprema, a princip rada se sastoji od vožnje po platformi za ispitivanje postavljenoj na kriostatsko postolje, pričvršćivanja ispred nosač te vizualnog, površinskog i volumenskog nerazornog ispitivanja. Proces RAMI metode procjene rizika započinje IDEFØ funkcijskom analizom čime je rad uređaja opisan na razini njegovih glavnih, srednjih i osnovnih funkcija. Temeljem funkcijske analize, formirana je FMECA tablica unutar koje su definirani načini, uzroci i učinci kvara. Ulazni podaci potrebni za kvantitativnu procjenu rizika zatim su prikupljeni korištenjem iskustva firme i podataka dostupnih od strane dobavljača. U sljedećem koraku je prikazana funkcijska međupovezanost u obliku blok dijagrama pouzdanosti te su temeljem ulaznih podataka provedene analize pouzdanosti i raspoloživosti. Na posljetku je proveden nastavak FMECA analize, gdje su kvarovi temeljem ulaznih podataka o pouzdanosti i održivosti te ITER tablica jakosti, učestalosti i uočljivosti kvantificirani i evaluirani u obliku malih, srednjih i velikih rizika. Prema provedenoj procjeni rizika identificirano je ukupno 118 rizika, od kojih je 11 malih rizika, 100 srednjih rizika i 7 velikih rizika. Prema uputama ITER organizacije, srednje i velike rizike je potrebno tretirani te su tako u posljednjem dijelu rada dani prijedlozi za njihovim smanjenjem. Posebna pozornost pridana je velikim rizicima koji se sastoje od slučajeva curenja vode, gubitka zraka unutar pneumatskog sustava te oštećenja robotske ruke. Kako je procjena rizika u ovome radu primijenjena na uređaj u konceptnoj fazi razvoja, smanjivanjem navedenih rizika u daljnjem razvoju očekuje se povećanje pouzdanosti i raspoloživosti rada WP6 opreme. |
| Abstract (english) | Risk is defined as the “effect of uncertainty on goals” and thus is a crucial factor in decision making. By applying risk assessment, risks can be identified, analyzed, and evaluated after which decisions can be made on how to treat them. The aim of this paper is thus to evaluate the risks involved in the use of a VVGS NDT device. The introductory part of the paper defines important concepts such as technical system, failure, and in-service inspection, while also introducing the company INETEC, whose device will be used in the ITER project. The second part of the paper consists of a risk assessment overview in the form of its history and structure, while some of the commonly used methods are also presented. Based on the instructions from the IO, the risk assessment in this paper was conducted using the RAMI method consisting of IDEFØ function analysis, FMECA and RBD. The third part of the paper thus consists of describing the process of the RAMI method, as well as defining the concepts of reliability, availability, maintainability and inspectability. The fourth part of the paper consists of a description of the device on which the risk assessment was performed and the risk assessment itself. The device is called WP6 equipment and the operating principle consists of driving on the cryostat inspection platform, positioning in front of a VVGS and performing the NDT process. The process of RAMI method begins with IDEFØ functional analysis, which describes the operation of the device at the level of its main, intermediate, and basic functions. Based on the functional analysis, a FMECA table was formed within which the modes, causes and effects of the fault were defined. The input data required for quantitative risk assessment was then collected using the experience and data available from INETEC and the suppliers. The functional interconnection is then presented in the form of RBD, and based on the input data, reliability and availability analyses are performed. Finally, the continuation of the FMECA analysis was performed, where failures based on reliability and maintainability input data and ITER tables of severity, occurrence and detection were quantified and evaluated in the form of small, medium, and large risks. According to the conducted risk assessment, a total of 118 risks were identified, of which 11 were small risks, 100 were medium risks and 7 were large risks. As per the instructions of the IO, medium and large risks need to be treated, so in the last part of the paper, suggestions for risk mitigation were given. Special attention is paid to the high risks consisting of water leakage, loss of air in the pneumatic system and damage to the robotic arm. As the risk assessment in this paper is applied to a conceptual device, reducing these risks in further development is expected to increase the reliability and availability of WP6 equipment. |
