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9 <br />modelling. The modelling should consider both partial and complete uncovering and the <br />transition from one of these states to the other. Also, the modelling should cover: (1) <br />thermal radiation, conduction, and steam or air convection; (2) air-zirconium and steam- <br />zirconium reactions; (3) variations along the fuel rod axis; and (4) radial variations within <br />a representative fuel rod, including effects of the pellet-cladding gap. Experiments will <br />probably be required to support and validate the modelling. <br />37. Until the problem of water loss is re-analyzed in this manner, there is no basis for <br />determining when fuel has been discharged for a sufficiently long period that it will not <br />suffer a runaway zirconium reaction in the event of water loss. If the problem were to be <br />properly analyzed through validated models, such a determination could be made within <br />some margin of error, but the determination should consider site-specific factors. For <br />example, the detailed design of a rack might be an important site-specific factor. <br />38. No determination of this kind has been made for pools C and D at Harris, nor does <br />the methodology now exist to make such a determination. In any case, there is nothing in <br />the license amendment application and its proposed modifications to the Harris Technical <br />Specifications which prohibits the placing of freshly discharged fuel in pools C and D. <br />Reports previously prepared for the NRC concede that freshly discharged fuel can <br />experience a runaway air-zirconium reaction in the event of complete water loss. <br />39. A variety of events, alone or in combination, could lead to partial. or complete <br />uncovering of spent fuel in the Harris pools. This class of events should be subjected to <br />the kind of systematic analysis that is performed in an IPE and an IPEEE. Relevant <br />events include: (1) an earthquake, cask drop, aircraft crash, human error, equipment <br />failure or sabotage event that leads to direct leakage from the pools; (2) siphoning of <br />water from the pools through accident or malice; (3) interruption of pool cooling, leading <br />to pool boiling and loss of water by evaporation; and (4) loss of water from active pools <br />into adjacent pools or canals that have been gated off and drained. Interactions with the <br />Harris reactor should be considered. For example, a reactor accident might release <br />radioactivity that precludes personnel access to the plant for purposes of maintaining or <br />restoring pool cooling. <br />I. Increased Probability or Consequences of Accidents Previously Evaluated <br />40. The Federal Register notice of this license amendment application claims that the <br />probability of a spent fuel assembly drop or a misloaded fuel assembly is not significantly <br />increased if the license amendment is approved and pools C and D are activated. This <br />claim is false, because activation of pools C and D will roughly double the total number <br />of fuel handling operations to be conducted at Harris. Assuming that the general nature <br />of fuel handling operations continues as before, the probability of a fuel assembly dxop or <br />misloaded fuel assembly, integrated over the entire period of the Harris operating license, <br />will increase significantly, by a factor of two. This point has been made by David <br />Lochbaum of the Union of Concerned Scientists, in a 22 January 19991etter to the NRC <br />Commissioners. A.copy of his letter is provided here as Attachment F. If probability is <br />integrated over the remaining period of the Harris operating license, rather than over its <br />total duration, then activation of pools C and D will more than double the probability of a <br />fuel assembly drop or a misloaded fuel assembly. <br />41. A spent fuel assembly drop or a misloaded fuel assembly are members of a broader <br />class of accidents that could arise during the movement of fuel from other CP&L stations <br />to Harris, and during fuel movement within Harris. This class of accidents will include <br />design-basis accidents and severe accidents. Assuming that the general nature of fuel <br />movement continues as before, the probability of accidents in this class, integrated over <br />