1 - Alaska Energy Data Inventory

a surge tank approximately 350 ft high with a 10 ft diameter, resulted in amaximum surge tank water surface elevation of 1,064 ft and a maximumpiezometer elevation at the unit of 1,302 ft. The Dowrshak model was usedin "WHAMO" for that analysis.(3) All of the earlier computer runs were made with assumedtailwater elevations of 11.4 ft because of assurances given by the StateFish and Wildlife Department that there would be no change in tailwaterelevation. This concept has recently been revised and minimum tailwatersare shown in figure 4 of Appendix B2.N. Crater Lake Phase Without A Surge Tank. Due to the significantexpense of constructing either an air chamber surge tank or a vented surgeshaft, a hydraulic analysis was performed to determine the feasibility ofbuilding the project without a surge tank or an air chamber.Transientanalyses were performed for the overspeed, load rejection, and load demandconditions at 5, 10, and 15 second wicket gate opening and closing rates aswell as an additional overs peed analysis for an increased turbine/generatorWR 2 of 2,000,000 lb-ft 2 • (Current design WR 2 = 1,075,000 lb-ft 2 .)The analyses were conducted on the "WHAMO" computer program and the resultsappear in figure 18 of Appendix B2. These results show that if the WR 2could be increased to 2,000,000 lb-ft, and the equivalent wicket gateopening and closing rates were increased from 5 seconds to 9.5 seconds, itwould be possible to keep the overspeed, maximum water hammer, gate shaftsurge and gate shaft drawdown within acceptable 1 imits.Some structuralchanges would be required, such as raising the elevation of the controlroom floor and lowering the crown of the power tunnel at the gate shaft.Further investigation revealed that the WR 2 of the turbine/generatorwould need to be at least 2,106,000 lb-ft 2 to provide adequate governingstabil ity of the system, as plotted on Gordon IS stabil ity curves as shownin figure 19 of Appendix B2.Although it appeared to be theoreticallyfeasible to eliminate the surge tank from the system by increasing WR2,generator manufacturers informed represent at i ves of NPD-HEDB and OCE that1,550,0001b-ft 2 was the maximum practical limit of WR 2 which could beincorporated into the turbi ne/generator for Crater Lake.the system with no surge tank from further consideration.Bl-39Th is e 1 imi nated