Assessing groundbreaking nuclear reactor vessel experiments
Divided into two levels, the priorities were for the data and models that would assess the feasibility of promulgating the In-Vessel Melt Retention (IVMR), and the time available before vessel failure. Secondary objectives determined the mode and location of vessel failure, melt discharged to the containment, gap cooling effectiveness, melt stratification effects and critical heat flux for the external head. Consisting of experiments and analysis development, the modelling activities focused on exploiting data obtained from experiments for creep deformation and the validation of industry structural codes. Whilst work was performed on the extension of melt natural convection analyses to consideration of stratification and mixing, other modelling activities were also conducted. Of all the project components the most important one was whereby data was obtained from melt pool convection and lower head creep failure and rupture. In order to achieve this information, the project broke new grounds in nuclear experimentation and subjected vessels to destructive testing. Containing heated melts and the lower head wall maintained at prototypic accident conditions, the vessels were intentionally ruptured. In addition to the ARVI project, two other projects were also conducted. The first concerned the effects that stratification and metal layer had on the thermal loads on the lower head wall during melt pool convection. The second project provided data and correlations on Gap cooling CHF, due to the external cooling of the lower head; and both projects support the findings of the ARVI project. Ultimately the derived results will ensure that the main objectives of the Fifth Framework Programme pertaining to key actions on nuclear fission will benefit in assisting the future safety of Europe's nuclear facilities. This will also lead to greater protection for the general public, improve European nuclear energy competitiveness and maintain high levels of expertise and competence on nuclear safety for the EU.