Abstract
After the severe accident (SA) occurred at the Three-Miles Island Nuclear Power Plant (NPP), important efforts on the investigation of the different phenomena during this kind of accidents have been started. Several experimental campaigns investigating one phenomenon at time or the combination of two or more phenomena have been performed. Today, the Phébus experimental campaign is probably the most important activity on the evaluation of the coupling among different phenomena. Four out of five tests investigated the degradation of an intact Pressurized Water Reactor (PWR) fuel bundle and the subsequent transport of Fission Products (FP) and Structural Materials (SM) through the primary circuit and into the containment, while the fifth test was only the degradation of a bed of PWR fuel bundle debris. These tests were performed between 1990 and 2010 at the CEA Cadarache laboratories (France) in a 5000:1 scaled facility. The main four tests varied the employed control rod materials, the fuel burn-up, and the oxidizing conditions of the atmosphere (strongly or weakly). The outcomes of this experimental campaign created a solid base for the understanding of the involved phenomena and allowed the development of models and software codes capable of simulating the evolution of a SA in a real NPP. ASTEC and MELCOR were two of the main SA codes profiting from the results of this Phébus campaign. These two codes were further improved in the latest years to account for the findings obtained in more recent experimental campaigns. A continuous verification and validation work is then necessary to check how the newer code’s versions reproduce the tests performed in these older experimental campaigns such as Phébus one. The present work is intended to be the final step of a series of publications covering the activities carried out at University of Pisa with the ASTEC and the MELCOR SA codes on the four Phébus tests employing an intact PWR fuel bundle. Because of the complexity and the extent of these tests, only the containment aspects were considered in the precedent works, i.e., only the thermal-hydraulics transient and its coupling with the FP and SM behavior. Then, general conclusions based on the outcomes of these precedent works are summarized in this work.
Highlights
After the Three-Miles Island Severe Accident (SA), important national and international projects and experimental campaigns have been carried out to get a better understanding of the key phenomena occurring in these kinds of accidents [1]
Both the ASTEC and the MELCOR codes have been updated to implement and reflect the findings coming from new experimental campaigns
A continuous verification and validation activity is necessary to ensure that the improvements/modifications introduced are valuable for the analysis of older experiments, such as the Phebus Fission Products (FP) tests
Summary
After the Three-Miles Island Severe Accident (SA), important national and international projects and experimental campaigns have been carried out to get a better understanding of the key phenomena occurring in these kinds of accidents [1] Among all these efforts, only the international Phebus FP experimental programme was devoted to the reproduction of a SA from the initiating event up to the release of radioactive substances into a Containment Vessel (CV) [2]. The aim of all these activities was to investigate the main parameters influencing the FP and SM behavior in the CV during the four main phases of each test (degradation, aerosol, washing, and chemistry phases) These analyses were performed with recent ASTEC and MELCOR code’s versions to evaluate the effects of the improvements and modifications implemented in both of them in the latest years to account for the new findings from international researches [13, 14]. The present paper is the last of five publications covering the Phebus tests executed with a solid PWR fuel bundle (FPT-0 [15], FPT-1 [16], FPT-2 [17], and FPT-3 [18] tests)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
