PBF (Power Burst Facility) severe fuel damage test 1-1: Volume 1, Test results report

A comprehensive evaluation of the Severe Fuel Damage (SFD) Test 1-1 performed in the Power Burst Facility (PBF) at the Idaho National Engineering Laboratory is presented. The test is part of an internationally sponsored light water reactor severe accident research program, initiated by the US Nuclear Regulatory Commission. Test SFD 1-1 was the second of four nuclear severe fuel damage tests performed in the PBF. The overall technical objective of the test was to contribute to the understanding of fuel bundle dynamics, hydrogen generation and fission product behavior during a high temperature, severe damage transient. The SFD 1-1 fuel bundle comprised 32, 0.9-m long, trace-irradiated (79 MWd/t) fuel rods surrounded by an insulating shroud. The experiment consisted of a transient in which the inlet coolant flow to the test bundle was reduced to 0.64 g/s, while the nuclear power was gradually increased until dryout, heatup, and rapid oxidation occurred. With sustained power and the heat of oxidation, temperatures continued to rise rapidly, approaching fuel melting and resulting in zircaloy melting, fuel liquefaction, material relocation, and fission product release. The approx.1 h transient, conducted at a pressure of 6.8 MPa, was terminated over a 1200-s time span by reducing the reactormore » power and cooling the bundle with an argon sweep gas before reflooding the bundle. A description and evaluation of the major phenomena, based upon the response of on-line instrumentation, analysis of fission product data, postirradiation examination of the fuel bundle, and calculations using the Severe Core Damage Analysis Package (SCDAP) Code, are presented.« less