Degradation and oxidation of B4C control rod segments at high temperatures. A review and code interpretation of the BECARRE program

Effect of B4C Absorber Material on Melt Progression and Chemical Forms of Iodine or Cesium under Severe Accident Conditions

“…The (2 bar) that existed during the BECARRE experiment, but occurs readily at temperatures and pressures exceeding 1500 K and 100 bar, respectively, 19) which supported the very low CH 4 generation observed in the experiment.…”

“…Concerning the oxidation of B 4 C, the molten materials prepared by the eutectic reaction between low viscosity B 4 C and the stainless steel cladding flowed down between the inner surface of the SS cladding tube and outer surface of the B 4 C Fig. 9 Test zone of BECARRE experimental device 19) A study based on the hermochemical equilibrium theory for this outcome found that H 4 generation hardly occurs under the low pressure conditions 2 bar) that existed during the BECARRE experiment, but ccurs readily at temperatures and pressures exceeding 1500 K nd 100 bar, respectively, 19) which supported the very low CH 4 eneration observed in the experiment. ) Released from the bundle, which reaches the containment vessel in gaseous (as HI) and vapor form (as SnI2, SnI4, I2MoO2 or others). )…”

“…Consequently, hydrogen generation by B 4 C oxidation was limited. 19) A photo of the radial cross-section after the heating experiment on the test zone of the BECARRE experimental device is shown in Fig. 10.…”

Chemical State Mapping of Degraded B4C Control Rod Investigated with Soft X-ray Emission Spectrometer in Electron Probe Micro-analysis

“…B 4 C is stable at the normal NPP operating temperature of ~300 °C, as it melts at 2450 °C 2 . However, the eutectic interaction of B 4 C with the adjacent stainless steel leads to its liquefaction at temperatures exceeding 1200 °C under severe accidental conditions 1 2 3 4 5 . The appearance of this liquid phase causes the phenomenon of candling and relocation, in which the liquid phase sinks to the bottom of the nuclear core.…”

Early phase fuel degradation in Phébus FP: Initiating phenomena of degradation in fuel bundle tests

“…A more correct relationship of 1-4 between carbonaceous gas and hydrogen production was similarly obtained, indicating that part of the solid B 4 C was transformed into molten eutectic material from the surrounding stainless steel and Zircaloy materials, and being either oxidised with different kinetics, or being relocated downward at temperatures where the oxidation is not significant. These experimental results were checked together with a close comparison with ASTEC calculations (de Luze, 2013).…”