b'P ROVING THE P RINCIPLEReactor Safety Tes t i n gT he INEL work in reactor safety was F U L L - L E N G T H E M E R G E N CY C O R E C O N T A I N M E N T A N A LY S I S P R O G RA Ma complex and detailed interactionbetween the familiar procedures of H EA T I N G T E S TS ( F L E C H T) Experiments were performed at Sandiascientific inquiry: making predictions Using twelve-foot non-nuclear bundles National Laboratory and in Idaho;and then verifying them with empirical of fuel rods, tests determined the effec- additional analytical work was done attests. Each test confirmed the predic- tiveness of emergency core cooling the INEL.tion or helped to refine the next itera- systems in pressurized-water reactors.tion. Computers made it E M E R G E N CY C O R E C O O L I N Gpossible to model systems withhuge numbers of variables. The S Y S T E M S A N A LY S I Ssafety tests at the INEL Combination of experimentalinvolved several interrelated and analytical work that evaluat-programs, among which were:ed and predicted how productsA D V A N C E D C O D E D EV E LO P M E N T made by various manufacturerswould actually perform. ResultsPredicted the thermal hydraulic of Semiscale and LOFTex pe r i-behavior of coolant in the pri- ments were part of this program.mary coolant system based onnew models. The models S E M I S C A L Eresulted from small-scale Experiments tested and verifiedexperiments, carefully instru- INEEL 82-4005 computer models of LOCAs. Inmented to obtain accurate data. the event of a leak in a primaryThe models were incorporated in an Developed at INEL, RELAP5 is a program that coolant system, water pressure wouldoverall code called RELAP. gives over 50,000 computational instructions to a fall, a process called blowdown.large computer. It calculates overall nuclear Semiscale studied this thermal-F U E L B E H A V I O R P R O G RA M power plant system responses to accidenthydraulic phenomenon in detail.Tested the performance of fuel pins in situations such as the one at Three Mile Island.conditions of normal and transient con- LO FT I N T E G RA L T E S T P R O G RA Mditions. Tests were done in the MTR, F I SS I O N P R O D U CT B E H A V I O RETR, and ATR. The work included the An experimental reactor providedE X P E R I M E N TS empirical data supporting behavior pre-creation and experimental confirmation dictions for pressurized-water reactorsof a Fuel Rod Analysis Program Small-scale tests helped assess the under LOCAconditions. The program(FRAP) using the Power Burst Facility. accuracy of computer models describ- evaluated engineered safety featuresing the release of fission products and and assessed the margins of safety inwhere they went after a loss-of-coolant their performance.accident (LOCA).2 30'