This document describes the experiment operating specifications for the Reactivity Initiated Accident (RIA) Scoping Test to be conducted in the Power Burst Facility (PBF) at the Idaho National Engineering Laboratory. The primary objectives of the RIA research are to determine fuel failure thresholds, modes, and consequences as functions of (a) enthalpy insertion, (b) irradiation history, and (c) fuel design. Coolant conditions of pressure, temperature, and flow rate that are typical of hot-startup conditions in commercial boiling water reactors (BWRs) will be used in the first six RIA tests, termed Series I.
This document describes the experiment operating specifications for the Reactivity Initiated Accident (RIA) Test RIA 1-2 to be conducted in the Power Burst Facility (PBF) at the Idaho National Engineering Laboratory. The RIA Series I research objectives are to determine fuel failure thresholds, modes and consequences as functions of enthalpy insertion, irradiation history, and fuel design. Coolant conditions of pressure, temperature, and flow rate that are typical of hot-startup conditions in commercial boiling water reactors {BWRs) will be used. The second test in Series I, Test RIA 1-2, will be comprised of four individual rods, each surrounded by a separate flow shroud. The four rods will be preirradiated. The specific objectives of the test are to: (1) characterize the response of preirradiated fuel rods during a RIA event conducted at BWR hot-startup conditions and (2) evaluate the effect of internal rod pressure on preirradiated fuel rod transient response. The test sequence will begin with steady state power operation to condition the fuel (pellet cracking and relocation) and determine the fuel rod power calibration. The loop will then be cooled down, the test train removed from the in-pile tube, and the cobalt flux wires that are mounted on each flow shroud will be replaced. The transient fuel rod energy deposition for the Test RIA 1-2 rods will be chosen from the fuel rod response vs. energy deposition observed in the first three phases of the RIA Scoping Test and the first test of Series J, Test RIA 1-1. The design of the test fuel rods, test assembly, and instrumentation associated with Test RIA 1-2 are described. The planned experiment conduct for the test is described. The data recording and reduction requirements are provided. The posttest operations support and the postirradiation examination requirements associated with Test RIA 1-2 are described.
This document describes the experiment operating specifications for the Reactivity Initiated Accident (RIA) Test RIA 1-1 to be conducted in the Power Burst Facility (PBF) at the Idaho National Engineering Laboratory. The RIA Series I research objectives are to determine fuel failure thresholds, modes and consequences as functions of enthalpy insertion, irradiation history, and fuel design. Coolant conditions of pressure, temperature, and flow rate that are typical of hot-startup conditions in commercial boiling water reactors (BWRs) will be used. The first test in Series I, Test RIA 1-1, will be comprised of four individual rods, each surrounded by a separate flow shroud. Two rods will be preirradiated and two rods will be unirradiated. The specific objectives of the test are to: (1) characterize the response of unirradiated and preirradiated fuel rods during a RIA event conducted at BWR hot-startup conditions and (2) evaluate test instrumentation response during an RIA. The test sequence will begin with steady state power operation to condition the fuel (pellet cracking and relocation) and determine the fuel rod power calibration. The loop will then be cooled down, the test train removed from the in-pile tube, and one of the unirradiated rods will be removed for fission product analysis and replaced with an identical unirradiated rod. The transient fuel rod energy deposition for Test RIA 1-1 will be chosen from the fuel rod response vs. energy deposition data observed in the first three phases of the RIA Scoping Test. It is anticipated that a fuel pellet surface energy deposition of about 1100 J/g will be required to ensure cladding failure of all four rods. The design of the test fuel rods, test assembly, and instrumentation associated with Test RIA 1-1 are described. The experiment conduct for the test is described. The data recording and reduction requirements are provided. The posttest support and the postirradiation examination requirements associated with Test RIA 1-1 are described.
The Reactivity 'Initiated Accident (RIA) test series to be conducted in the Power Burst Facility (PBF) has been designed.to determine fuel failure thresholds, modes, and consequences as a function of energy deposition, irradiation history, and fuel design. The RIA Scoping Test will be comprised of five single unirradiated rod sub-tests. The first rod will be subjected to a series of transient power bursts of increasing energy release to determine the energy deposition at cladding failure. The second and third rods will be subjected to energy depositions near that which caused failure of the first rod, to further define the failure threshold. Rods four and five will be subjected to large radially averaged energy depositions, 1990 and 2510 J/g respectively, to investigate facility safety concerns. Several analyses were performed to predict test fuel rod and system behavior during the five RIA Scoping Test phases. A reactor physics analysis was performed to obtain the relationship between test fuel rod and reactor core energy during a power transient. The calculations were made with the RAFFLE computer code. The thermal-hydraulic behavior of the test rod coolant was investigated for pellet surface energy depositions of 900, 1125, and 1350 J/g for the first three phases of the Scoping Test. The RELAP4 computer code was used for these thermal-hydraulic analyses. The results of the RELAP4 calculations provided input to the FRAP-T4 computer code for three fuel rod behavior analyses at pellet surface energy depositions of 815, 1020, and 1225 J/g. A cladding embrittlement analysis, using the results of the FRAP-T4 calculations as input, was made to investigate the cladding oxidation mode of rod failure for the lower energy phases. BUILD5 was the analytical tool used in this investigation. Finally, the pressure pulses generated as a result of failure of the test fuel rods in the final two high energy test phases were calculated using the SPIRT computer code. In previous reactivity initiated accident tests performed in the SPERT, TREAT, and NSRR facilities a pellet surface energy deposition of 12.350 x 103 J/cm3 was identified as the failure threshold for unirradiated fuel rods with the ambient test conditions of 300 K, 0.1 MPa, and no forced flow. This volumetric energy deposition is equivalent to a pellet surface energy deposition of 1190 J/g (284 cal/g) when the RIA-ST fuel pellet density of 10.365 g/cm3 is considered. ·For no-flow conditions, it was further observed that the presence of a flow shroud caused a reduction of up to 10% in the failure threshold. The modes of failure seen in the previous tests were cladding embrittlement and low pressure rupture as the zircaloy melting temperature was approached. In general, the rod failures occurred only when a peak cladding temperature of 2073 K or above was reached. Based on the analyses, it is predicted that the test fuel rod energy deposition failure threshold will be 1035 J/g (247 cal/g) at the pellet surface for the fuel rods used in the initial three phases of the RIA Scoping Test. The initial coolant conditions for these cases are equivalent to a fuel enthalpy of 69 J/g (16.5 cal/g) at the fuel surface over ambient conditions. When the difference in initial coolant conditions is considered, the total fuel enthalpy increase leading to cladding failure observed in the previous RIA tests is equivalent to 1122 J/g (268 cal/g) at the fuel pellet surface. The difference between the predicted failure threshold value and that observed in previous tests (87 J/g) is believed to be a combined result of the presence of a flow shroud and uncertainies in the computer codes used to make the predictions. The mode of failure according to the analyses will be rupture due to high temperature cladding weakening. The consequences of these failures are predicted to he minimal. The mode of failure for the high energy phases of the Scoping Test will be cladding rupture due to internal rod pressurizati ...
The Reactivity Initiated Accident Scoping Test (RIA-ST) was successfully completed August 30, 1978. The test was introductory to the RIA Series 1 tests and was designed to investigate and resolve several anticipated problem areas prior to performance of the first test of the series, Test RIA 1-1. The RIA Scoping Test, as performed, consisted of four separate single-rod experiment phases. The first three phases were performed with shrouded fuel rods of 5.8 wt.% enrichment. They were subjected to power bursts resulting in total fuel surface energies ranging from 205 to 261 cal/q at the axial peak elevation. The fourth phase consisted of a 20 wt.% enriched, shrouded fuel rod which was subjected to a power hurst that deposited a total radially averaged energy of 527 cal/g. The primary objectives of the Scoping Test were defined as follows: (1) Determine the applicability of extrapolating low-power steady state calorimetric measurements and self-powered neutron detector (SPND) output to determine fuel rod energy depositions during a power burst. (2) Determine the enerqy deposition failure threshold for unirradiated fuel rods at BWR hot-startup coolant conditions. (3) Determine the magnitudes of oossible pressure pulses resulting from rod failure. (4) Determine the sensitivity of the test instrumentation to high transient radiation exposures. In general, the energy deposition values for the Scoping Test derived from the SPND output were 25% higher than those obtained from the core ion chamber data. Determining which values are correct will require radiochemical analysis of the fuel rods which will take several months. At present, it apoears that the SPND derived energies are in error because of excellent agreement between the calculated and measured power calibration results and the agreement between the predicted failure threshold and that seen using the core ion chamber derived energies. Meeting the second objective was accomplished during the first three test phases by subjecting the fuel rods to energy depositions which bracketed the failure threshold. The failure threshold in terms of total pellet surface energy at the axial flux peak was found to be between 218 cal/g where no rod failure occurred and 256 cal/g where · rod failure did occur. The experiment predictions indicated that the failure threshold would be 262 cal/g at the pellet surface. Only the fourth experiment phase (527 cal/g) resulted in a pressure pulse upon rod failure. The best indication of source pressure was the reading from a 69 MPa EG & G pressure transducer at the flow shroud inlet. This pressure transducer indicated a pressure pulse upon rod failure of 28.2 MPa with a rise time of 1.6 ms. The source pressure was attenuated considerably outside the shroud region as indicated by pressure transducers in the upper plenum of the in-pile tube and in the flow bypass region. The maximum pressure indicated outside the flow shroud was 2.1 MPa. In general, instrumentation sensitivity to radiation was minimal. The most significant instrumentation problem during the power bursts was a false flowrate indication by the flow turbines. This problem is being examined. The Kaman and Bell & Howell pressure transducers showed the least sensitivity to radiation of the pressure measurement devices. The EG & G transducers were most sensitive. The locked linear variable differential transformer (LVDT) gave no indication of radiation sensitivity as its response during the burst was a straight line. The strain gages were very sensitive to radiation, indicating a strain increase of 70% with the second burst of RIA-ST-1. The Type S thermocouple did not exhibit significant radiation sensitivity. In addition, the RIA Scoping Test has provided data on the consequences of fuel rod failure during a RIA event at BWR hot startup conditions. Posttest examination of the fuel rods from the first two phases of the test revealed large quantities of UO2 fuel missing from the cladding. Fuel rod fa ...
