Radiation Damage to the graphite moderator has played an important role in the history of reactor operation at Hanford. The operational problems, potential and real, which result from dimensional instability, stored energy, and gasification, as well as the solutions to these problems are discussed. The key to the graphite problems is operating temperature and its control. At present, stack expansion remains in the fringe regions of the original reactors, which coupled with the contraction of the central region gives rise to curvature problems in the top portion of the reactors. Stored energy is not a safety hazard because the release spectrum is such that a spontaneous and self sustained release cannot occur. Oxidation of the graphite moderator is controlled by maintaining operating temperature of the stack such that no significant amount of oxidation occurs.

The interaction between graphite and a number of metals and alloys was studied at 1850 deg F in 250-hr tests. Some materials were also tested at 1650 and 1850 deg F in 1000-hr tests. The graphite was heated in intimate contact with the test metal in welded metallic capsules. The exen of the reaction was judged on the basis of metallographic examinations and hardness traverses on cross sections of the reacted elements. Copper was the least reactive material tested in contact with graphite. Nickel was only slightly more reactive. Outside of a veny hard carbide band at the graphite-metal interface, no evidence of interaction of carbon with molybdenum was found. Inconel X was the most compatible alloy tested in contact with graphite, although some pickup was observed. Alnicro was the next best alloy. Nichrome V, Inconel, and Types 316 and 318 stainess steels were all much more reactive. Copper and chromium plating reduced the rate of diffusion of carbon into Type 316 stainless steel. Nickel plating was less effective for this purpose. (auth)

There may be an advantage to designing the HRE-3 vertical shell and tube slurry heat exchanger as a feedwater heater rather than as a steam generator from the standpoint of space requirement and blowdown problems. This study of the effect of this arrangement on the thermal efficiency of the heat-power cycle indicates that the gross electrical generating capacity of HRE-3 would be reduced by about 500-kw, or about 3 to 4% of the output. It is concluded that, (a) there is sufficient merit in using the exchanger as a feedwater heater to warrant continued study of the concept, and (b) the effect on the thermal efficiency is so small as to not be a major deciding influence. (auth)

From abstract: "The Safety Program of the University of California Radiation Laboratory at Livermore, California, is discussed in terms of the functions of the six independent safety groups that comprise the laboratory's primary safety organization, namely, Industrial Safety, Medical Safety, Fire Prevention and First Aid, Health Chemistry, Health Physics, and High-Explosive Safety Groups."