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HRP IN-PILE CORROSION TEST LOOPS, OPERATION OF IN-PILE LOOP L-2-19

Description: Loop L-2-19 operated in HB-2 of the WTR for 1148.9 hours of circulation and 2705 Mwhr of LITR operation. The solution contained 0.17 m enriched UO/sub 2/ SO/sub 4/, 0.02 m CuSO/sub 4/, 0.12 m excess H/sub 2/SO/sub 4/, and 0.20 m Li/sub 2/SO/sub 4/ in H /.sub 2/O, The main stream was 280 deg C and the pressurizer 295 deg C. There was no unusual difficulty during loop operation. A revised loop sample procedure gave better flushing of the sample lines. Four valves failed due to severe corrosion and fracturing of the 420 SS stems. 1-131 was not detected in a sample of gas taken from the gas hold-up tank. The run was terminated when the circulating pump failed. (auth)
Date: June 19, 1958
Creator: Lorenz, R.A.
Partner: UNT Libraries Government Documents Department

ANS-5. 4 fission gas release model. III. Low temperature release

Description: A comittee of the American Nuclear Society, the ANS 5.4 Working Group, has formulated models for the release of fission gas from light water reactor (LWR) fuel operating at low temperature. The model for the release of stable fission gas and /sup 85/Kr shows (as the data from which it was derived) that the fractional release at 30,000 to 35,000 MWd/MT should be less than 0.5% as long as the peak centerline temperature remains sufficiently low. A second model is used to calculate the release of shorter half-life isotopes that reach production-decay equilibrium.
Date: January 1, 1979
Creator: Lorenz, R.A.
Partner: UNT Libraries Government Documents Department

Vaporization of structural materials in severe accidents. [PWR; BWR]

Description: Vaporized structural materials form the bulk of aerosol particles that can transport fission products in severe LWR accidents. As part of the Severe Accident Sequence Analysis (SASA) program at Oak Ridge National Laboratory, a model has been developed based on a mass transport coefficient to describe the transport of materials from the surface of a molten pool. In many accident scenarios, the coefficient can be calculated from existing correlations for mass transfer by natural convection. Data from SASCHA fuel melting tests (Karlsruhe, Germany) show that the partial pressures of many of the melt components (Fe, Cr, Co, Mn, Sn) required for the model can be calculated from the vapor pressures of the pure species and Raoult's law. These calculations indicate much lower aerosol concentrations than reported in previous studies.
Date: January 1, 1982
Creator: Lorenz, R.A.
Partner: UNT Libraries Government Documents Department

Release and transport of fission product cesium in the TMI-2 accident

Description: Approximately 50% of the fission product cesium was released from the overheated UO/sub 2/ fuel in the TMI-2 accident. Steam that boiled away from a water pool in the bottom of the reactor vessel transported the released fission products throughout the reactor coolant system (RCS). Some fission products passed directly through a leaking valve with steam and water into the containment structure, but most deposited on dry surfaces inside of the RCS before being dissolved or resuspended when the RCS was refilled with water. A cesium transport model was developed that extended measured cesium in the RCS back to the first day of the accident. The model revealed that approx.62% of the released /sup 137/Cs deposited on dry surfaces inside of the RCS before being slowly leached and transported out of the RCS in leaked or letdown water. The leach rates from the model agreed reasonably well with those measured in the laboratory. The chemical behavior of cesium in the TMI-2 accident agreed with that observed in fission product release tests at Oak Ridge National Laboratory (ORNL).
Date: January 1, 1986
Creator: Lorenz, R.A. & Collins, J.L.
Partner: UNT Libraries Government Documents Department

Estimated amount of /sup 85/Kr available for release from intact fuel rods in the Three Mile Island Unit 2 Nuclear Power Station

Description: Reactor core dismantling operations planned for the Three Mile Island Unit 2 Power Station could cause rupture of any fuel rods that might have survived the accident in a leak-tight condition. Calculations were performed in an attempt to determine the amount of /sup 85/Kr that might be present in the free gaseous form in the plenum and void spaces of such fuel rods. Estimates were made of the number of fuel rods surviving intect, the temperature transient to which they were exposed, the amount of /sup 85/Kr orginally produced in the fuel in these rods, and the amounts released from the UO/sub 2/ matrix to the plenums both before the accident and during the accident (as a result of heatup). Since there is considerable uncertainty in these quantities, particularly the number of surviving fuel rods and the temperature transient they experienced, an analysis was made of the importance of these assumptions. Results of the analysis show that approx.30 Ci of /sup 85/Kr could exist in the free state in the plenums of intact rods; however, this quantity might range anywhere from 0 to 100 Ci. 8 figures, 6 tables.
Date: October 1, 1983
Creator: Lorenz, R.A.
Partner: UNT Libraries Government Documents Department

LWR source terms for loss-of-coolant and core melt accidents

Description: Fission product source terms for loss-of-coolant and core meltdown accidents in light water reactors are reviewed. The results presented in the Reactor Safety Study are summarized, and modifications of these results, due to more recent experimental studies, are described.
Date: January 1, 1980
Creator: Malinauskas, A.P.; Lorenz, R.A.; Albrecht, H. & Wild, H.
Partner: UNT Libraries Government Documents Department

Fission product source terms for the LWR loss-of-coolant accident

Description: Models for cesium and iodine release from light-water reactor (LWR) fuel rods failed in steam were formulated based on experimental fission product release data from several types of failed LWR fuel rods. The models were applied to a pressurized water reactor (PWR) undergoing a hypothetical loss-of-coolant accident (LOCA) temperature transient. Calculated total iodine and cesium releases from the fuel rods were 0.053 and 0.025% of the total reactor inventories of these elements, respectively, with most of the release occurring at the time of rupture. These values are approximately two orders of magnitude less than releases used in WASH-1400, the Reactor Safety Study.
Date: July 1, 1980
Creator: Lorenz, R.A.; Collins, J.L. & Malinauskas, A.P.
Partner: UNT Libraries Government Documents Department

Fission product release from defected LWR fuel rods

Description: Experiments conducted at Oak Ridge National Laboratory both with fission product simulants and with irradiated commercial fuel have been utilized to develop a semi-empirical model of fission product release from defected Light Water Reactor (LWR) fuel rods. At fuel temperatures less than 1200/sup 0/C, releases occur from fission products previously accumulated in the pellet-to-cladding gap region. In this temperature range, the release of species of moderate volatility is postulated to result from two processes. The first of these, which occurs during the period of fuel clad rupture, is due to the transport of the fill and fission product gases as they are vented through the cladding defect. The second mechanism for release, which is time-dependent, involves the diffusional transport of the semi-volatile species to the point of clad rupture through the interconnected voids (the pellet-to-cladding gap and cracks in fuel pellets) within the fuel rod.
Date: January 1, 1979
Creator: Malinauskas, A.P.; Lorenz, R.A. & Collins, J.L.
Partner: UNT Libraries Government Documents Department

Review of tellurium release rates from LWR fuel elements under accident conditions

Description: Although fission product tellurium presents a potentially significant radiohazard, its release and transport in source-term experiments is frequently overlooked because it does not possess a readily measurable, gamma emission; moreover, a recent study emphasized noble gas, iodine and cesium release from LWR fuel elements because of the large data base that exists for these materials. Some new tests show that in some cases tellurium may be held up in core material to a greater degree than previously assumed - an observation that prompts a careful reappraisal of the existing tellurium-release data and its chemical foundation.
Date: January 1, 1983
Creator: Lorenz, R A; Beahm, E C & Wichner, R P
Partner: UNT Libraries Government Documents Department

Behavior of Cs, I, and Te in the fission product release program at ORNL

Description: Experiments have been conducted at ORNL with highly irradiated light-water reactor (PWR and BWR) fuel rod segments to investigate fission product release in steam in the temperature range 500 to 2000/sup 0/C. Objectives were to quantify and characterize the releases under conditions postulated for LOCA) and severe accident conditions. In all, 26 experiments have been conducted - 24 with high burnup and 2 with low burnup fuels. To aid in the interpretation of fission product release, 12 implant and 18 control experiments were also conducted; the behavior of HI, I/sub 2/, Cs/sub 2/O, CsOH, Te, and TeO/sub 2/ (individually and in different combinations) was studied. This paper discusses only the observed behavior of cesium, iodine, and tellurium. Cs and I were released primarily as CsOH and CsI, and Te release was controlled by steam oxidation of Zircaloy cladding.
Date: January 1, 1984
Creator: Collins, J.L.; Osborne, M.F. & Lorenz, R.A.
Partner: UNT Libraries Government Documents Department

Behavior of fission product tellurium under severe accident conditions

Description: Fission product release tests at Oak Ridge National Laboratory (ORNL) have provided new experimental data that help characterize the behavior of tellurium under severe light-water reactor (LWR) accident conditions. The release of tellurium from the fuel rods is dependent upon the rate and extent of cladding oxidation. Tellurium has been found to be considerably retained by metallic Zircaloy cladding at test temperatures up to 1975/sup 0/C. The results indicate that the tellurium is bound by the Zircaloy cladding as zirconium telluride, but once the available zirconium metal is oxidized by the steam, tellurium is released in favor of continued zirconium oxide formation. The collection behavior of the released tellurium indicates that it is probably released from the fuel rods as SnTe and CsTe, rather than as elemental tellurium.
Date: January 1, 1986
Creator: Collins, J.L.; Osborne, M.F. & Lorenz, R.A.
Partner: UNT Libraries Government Documents Department

Effects of time and other variables on fission product release rates

Description: The releases of krypton and cesium from highly irradiated LWR fuel have been examined in detail. The main interest has been the effect of time on the rate of release and the effects of heatup and cooldown cycles. The minute-by-minute release rates for fission product /sup 85/Kr from commercial fuel irradiated in the H.B. Robinson PWR are shown. The release rate, fraction per minute, is calculated in the same manner as release rates given in NUREG-0772; the fission gas, cesium, and iodine release rate curve from that report is also shown.
Date: January 1, 1986
Creator: Lorenz, R.A.; Osborne, M.F. & Collins, J.L.
Partner: UNT Libraries Government Documents Department

Fission product release from simulated LWR fuel. [Loss of coolant or spent fuel transportation accident conditions]

Description: A series of tests has been conducted with simulated LWR fuel as part of a program for determining the quantities and characteristics of radiologically significant fission products that can be released under postulated spent-fuel transportation accident (SFTA) conditions and successfully terminated loss-of-coolant accident (LOCA) conditions. These tests were performed in either flowing-steam or dry-air atmospheres with Zircaloy-4-clad fuel-rod segments that contained unirradiated UO/sub 2/ pellets coated with radioactively traced CsOH, CsI, and TeO/sub 2/. A summary of the test conditions and amounts released are given. Cesium release associated with the implanted CsOH appeared to be limited by the formation of low-volatility uranate compounds. Iodine release was observed primarily as CsI, but also as I/sub 2/; in addition, at test temperatures of 900/sup 0/C and above, significant migration of the CsI to the cooler ends of the fuel-rod segments was noted. Tellurium release was markedly restricted by rapid reaction with the Zircaloy cladding. The tests in air yielded enhanced releases of cesium and iodine, and considerable swelling of the oxidized UO/sub 2/. As anticipated, measured release fractions were greater when the test rods were ruptured at temperature by internal pressure than when the cladding failures were machined in the rods prior to testing.
Date: July 1, 1978
Creator: Lorenz, R.A.; Collins, J.L. & Manning, S.R.
Partner: UNT Libraries Government Documents Department

Fission-product release from irradiated LWR fuel

Description: An experimental investigation of fission product release from commercial LWR fuel under accident conditions is being conducted at Oak Ridge National Laboratory (ORNL). This work, which is sponsored by the US Nuclear Regulatory Commission (NRC), is an extension of earlier experiments up to 1600/sup 0/C and is designed to obtain the experimental data needed to reliably assess the consequences of accidents for fuel temperatures up to melting. The objectives of this program are (1) to determine fission product release rates from fully-irradiated commercial LWR fuel in high-temperature steam; (2) to collect and characterize the aerosol released; (3) to identify the chemical forms of the released material; (4) to correlate the results with related experimental data and develop a consistent source term model; and (5) to aid in the interpretation of tests using simulated LWR fuel.
Date: January 1, 1982
Creator: Osborne, M.F.; Lorenz, R.A. & Wichner, R.P.
Partner: UNT Libraries Government Documents Department

Modeling fission product release from ruptured LWR fuel rods

Description: The principal objectives of the fission product release program are to determine the quantity of radiologically significant fission products released from defected LWR fuel rods under accident conditions, identify their chemical and physical forms, and interpret the results for use as input to computer models of postulated transportation and loss-of-coolant accidents. Experimental work with flowing steam in the temperature range 500 to 1200/sup 0/C and with dry air at 500/sup 0/C and 700/sup 0/C has been completed. One series of tests, the Implant Test Series, employed simulated fission products which were coated on unirradiated UO/sub 2/ fuel pellets; a second series, the Low Burnup Fuel Test Series, used fuel capsules irradiated to 1000 MWd/MT at high heat rating (560 to 660 W/cm), and a third series of experiments, the High Burnup Test Series, used fuel irradiated to 30,000 MWd/MT in the H.B. Robinson reactor at low heat rating (175 to 320 W/cm). Sufficient analytical results have been obtained to permit the formulation of a preliminary empirical model for cesium release in steam. The model assumes that cesium release is the sum of two components: burst release (that carried out with escaping plenum gas when the rod ruptures) and diffusion release (that diffusing from the gap space after the plenum gas has vented).
Date: January 1, 1978
Creator: Lorenz, R.A.; Collins, J.L. & Malinauskas, A.P.
Partner: UNT Libraries Government Documents Department

Fission product source terms for the LWR loss-of-coolant accident

Description: The principal objectives of the fission product release program currently in progress at Oak Ridge National Laboratory are to determine the quantity of radiologically significant fission products released from defected light water reactor (LWR) fuel rods under accident conditions, identify their chemical and physical forms, and interpret the results for use as input to computer models of postulated spent fuel transportation accidents (SFTAs) and loss-of-coolant accidents (LOCAs). The purpose of this paper is to summarize the source term models, which have been developed for cesium and iodine by this program, and to demonstrate the application of the source term models to the analysis of cesium and iodine release during a Pressurized Water Reactor (PWR) LOCA.
Date: January 1, 1978
Creator: Lorenz, R.A.; Collins, J.L. & Malinauskas, A.P.
Partner: UNT Libraries Government Documents Department

Fission product release from fuel under LWR accident conditions

Description: Three tests have provided additional data on fission product release under LWR accident conditions in a temperature range (1400 to 2000/sup 0/C). In the release rate data are compared with curves from a recent NRC-sponsored review of available fission product release data. Although the iodine release in test HI-3 was inexplicably low, the other data points for Kr, I, and Cs fall reasonably close to the corresponding curve, thereby tending to verify the NRC review. The limited data for antimony and silver release fall below the curves. Results of spark source mass spectrometric analyses were in agreement with the gamma spectrometric results. Nonradioactive fission products such as Rb and Br appeared to behave like their chemical analogs Cs and I. Results suggest that Te, Ag, Sn, and Sb are released from the fuel in elemental form. Analysis of the cesium and iodine profiles in the thermal gradient tube indicates that iodine was deposited as CsT along with some other less volatile cesium compound. The cesium profiles and chemical reactivity indicate the presence of more than one cesium species.
Date: January 1, 1983
Creator: Osborne, M.F.; Lorenz, R.A.; Norwood, K.S.; Collins, J.L. & Wichner, R.P.
Partner: UNT Libraries Government Documents Department

Fission product release from highly irradiated LWR fuel

Description: A series of experiments was conducted with highly irradiated light-water reactor fuel rod segments to investigate fission products released in steam in the temperature range 500 to 1200/sup 0/C. (Two additional release tests were conducted in dry air.) The primary objectives were to quantify and characterize fission product release under conditions postulated for a spent-fuel transportation accident and for a successfully terminated loss-of-coolant accident (LOCA). In simulated, controlled LOCA-type tests, release at the time of rupture proved to be more significant than the diffusional release that followed. Comparison of the release data for the dry-air tests with the release data of similarly conducted tests in steam indicated significant increases in the releases of iodine, ruthenium, and cesium in air. Various parameters that affect fission product release are discussed, and experimental observations and analysis of the chemical behavior of releasable fission products in inert, steam, and dry-air atmospheres are examined.
Date: February 1, 1980
Creator: Lorenz, R.A.; Collins, J.L.; Malinauskas, A.P.; Kirkland, O.L. & Towns, R.L.
Partner: UNT Libraries Government Documents Department

Characterization and chemistry of fission products released from LWR fuel under accident conditions

Description: Segments from commercial LWR fuel rods have been tested at temperatures between 1400 and 2000/sup 0/C in a flowing steam-helium atmosphere to simulate severe accident conditions. The primary goals of the tests were to determine the rate of fission product release and to characterize the chemical behavior. This paper is concerned primarily with the identification and chemical behavior of the released fission products with emphasis on antimony, cesium, iodine, and silver. The iodine appeared to behave primarily as cesium iodide and the antimony and silver as elements, while cesium behavior was much more complex. 17 refs., 7 figs., 1 tab.
Date: January 1, 1984
Creator: Norwood, K.S.; Collins, J.L.; Osborne, M.F.; Lorenz, R.A. & Wichner, R.P.
Partner: UNT Libraries Government Documents Department