The Reaction of Steam With Large Specimens of Graphite for the Experimental Gas-Cooled Reactor

Abstract

NOTICE T h i s document contoins informotion of AESTRACTCarbon reaction rates and hydrogen generation rates have been determined for high pressure, high temperature steam flowing through a full scale EGCR fuel element graphite sleeve (Speer 9Ol-RYL) and a geometrically identical sleeve machined from EGCR moderator graphite (National Carbon Company).Tests were made in the temperature range of 1200 to 1600"~ with both graphite sleeves. To determine the effect of pressure from 30 to 300 psig, test data were obtained using an EGCR fuel element graphite sleeve. On both specimens, tests were also conducted at different steam flow rates. Exposure of the graphite to steam over a period of time roughens the surface thus increasing the reactive surface area. This burn-off of graphite results in an increase in the nominal reaction rate. was 5.6 g/hr-ft* at 155 psig, 1600"~ and approximately 4.0% burnoff. The reaction rate of the EGCR moderator graphite (National Carbon Company) was greater than the EGCR fuel element sleeve graphite (Speer 901-RYL) by a factor of 3.0 at 1600"~. nificant effects of pressure or steam flow rate were noted. The moderator graphite was exposed to 1550°F steam for 136 hr and 1580"~ steam for 41 hr. After exposure to steam at these and lower temperatures for approximately 900 hr, the EGCR moderator graphite could be crumbled very easily. The EGCR fuel element graphite which appeared structurally sound after the test, was exposed to steam for a l o n g e r t o t a l t i m e but only for 48 hr at a maximum temperature of 1580'~.The reaction rate of the EGCR fuel element sleeve graphite No sigc

Air Ingress Analyses on a High Temperature Gas-Cooled Reactor

“…The transition temperature depends upon impurities in the graphite or reacting gas, microstructure of the graphite, and the type and concentration of the reacting gas (Veet al 1978, Bunnell et al, and 1987. Gulbransen et al, 1964, Helms and MacPherson, 1965. The transition temperature between Regime 1 and Regime 2 is 395K as shown in Figure 2.…”