b'P ROVING THE P RINCIPLEtube, they inserted a camera and took We examined the recovered central conSubsequently,-as the unit hit the ceiling,pictures inside the core.trol rod, plug, and housing mechanism the extension rod was forced back downcarefully in the Hot Shop. The assemblyto nearly the zero withdrawn position.29The GE team had for months been had been recovered essentially with theexamining debris fragments and other rod in the down position. However, Scratch marks had been made on therecovered reactor parts in an attempt to upon disassembly, scratch marks on theway back down, confirming that the rodacquire as much information as possi- rod extension and the inside of the originally had been withdrawn 26 1/4ble before having to take the drastic guide tube clearly showed that the inches. That the rod had been with-action of cutting the pipes connecting guide tube had collapsed, the result of drawn and then jammed back downthe vessel to the rest of the plants the 10,000-pound water hammer pres -into the reactor to its safe positionequipment. Kunze recalled: sure, and had seized the rod extensionafter hitting the ceiling was a bizarreat the 26 1/4 inch withdrawn position. coincidence. One finding had led toOur main concern was how to cut thoselarge pipes so that a crane could lift theSchematic of SL-1 reactor.vessel up thirteen feet and then out andonto a truck. At first we envisioned nomethod except to use manpower in theform of many welders with their pipe-cutting torches, taking turns cutting asmuch pipe as possible before receivingtheir allowable maximum radiationdose.But we continued to play around withbasic physics ideasand came acro s sthe idea that the water, ejected upwardby the nuclear steam explosion, hadt r a n s f ered its momentum to the vessel, rp e rhaps sufficiently to cause the vesselto break the pipes and be lifted. Our cal -culations indicated that the vessel mayhave risen enough to hit the ceilingimmediately following the brief nuclearexcursion. So we took a close look at thefan floor, that is, the ceiling of the re a c -tor room, and saw that certain smalldents matched up with the head of thevessel. Now we saw that there was noneed to worry about how to cut thepipes. Much personnel risk and engi -neering frustration had been eliminated,all the result of the nature of this stillsomewhat mysterious accident.1 4 8'