8 research outputs found
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Calculation of the proportion of reactive waste for hydrogen ignition scenario
This study was conducted as outlined in NHC Letter of Instruction 9751330 dated February 247 1997 and entitled {open_quotes}Analysis by Pacific Northwest National Laboratory to Support a Safety Assessment for Rotary Mode Core Sampling in Flammable Gas Watchlist Tanks{close_quotes}. As prescribed in this letter, the results of this study were provided to Los Alamos National Laboratory (LANL) to revise the safety assessment document. Sampling Hanford tanks with a rotary drill could result in a drill-bit overheating accident which could ignite flammable gases present in the tanks. According to calculations, an over-heated drill bit could not get hot enough to ignite the hydrogen directly. However, an overheated drill bit could ignite saltcake waste containing high concentrations of organics, and a local organics burn would achieve sufficient temperature to ignite flammable gas present in the waste. This report estimates one quantity required to evaluate this particular accident scenario; the fraction of reactive waste in the tank waste. Reactive waste is waste that contains sufficient organic carbon and a low enough moisture content to ignite when in contact with an over-heated drill bit. This report presents a methodology to calculate the proportion of reactive waste for the 100 series tanks, using sampling data from tank characterization studies. The tanks are ranked according to their reactive waste proportions, and confidence limits are assigned to the estimates
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In-tank photo analysis
This report documents an analysis performed by Pacific Northwest Laboratory (PNL) of photographs showing the interior of a single shell tank (SST) at the Hanford site. This report shows that in-tank photos can be used to create a plan-view map of the waste surface inside a tank, and that measuring the elevation of the waste surface from the photos is possible, but not accurate enough to be useful at this time. In-tank photos were acquired for Tanks BX111 and T111. The BX111 photos were used to create the waste surface map and to measure the waste surface elevation. T111 photos were used to measure the waste surface elevation. Uncertainty analyses of the mapping and surface elevation are included to show the accuracy of the calculations for both methods
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Calculation of combustible waste fraction (CWF) estimates used in organics safety issue screening
This report describes how in-tank measurements of moisture (H{sub 2}O) and total organic carbon (TOC) are used to calculate combustible waste fractions (CWF) for 138 of the 149 Hanford single shell tanks. The combustible waste fraction of a tank is defined as that proportion of waste that is capable of burning when exposed to an ignition source. These CWF estimates are used to screen tanks for the organics complexant safety issue. Tanks with a suitably low fraction of combustible waste are classified as safe. The calculations in this report determine the combustible waste fractions in tanks under two different moisture conditions: under current moisture conditions, and after complete dry out. The first fraction is called the wet combustible waste fraction (wet CWF) and the second is called the dry combustible waste fraction (dry CWF). These two fractions are used to screen tanks into three categories: if the wet CWF is too high (above 5%), the tank is categorized as unsafe; if the wet CWF is low but the dry CWF is too high (again, above 5%), the tank is categorized as conditionally safe; finally, if both the wet and dry CWF are low, the tank is categorized as safe. Section 2 describes the data that was required for these calculations. Sections 3 and 4 describe the statistical model and resulting fit for dry combustible waste fractions. Sections 5 and 6 present the statistical model used to estimate wet CWF and the resulting fit. Section 7 describes two tests that were performed on the dry combustible waste fraction ANOVA model to validate it. Finally, Section 8 presents concluding remarks. Two Appendices present results on a tank-by-tank basis
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Probability of ignition of reactive wastes by rotary sampling drills
Sampling with a rotary drill could potentially cause a fire in some Hanford tanks. If the rotary drill experiences a failure while in fuel-rich, dry waste, the waste could be ignited by the hot drill bit. For the saltcake tanks subject to this hazard, this report presents a methodology for calculating the probabilities of fire due to core drill failure. The methodology utilizes sampling data from tank characterization studies to determine the amount of reactive waste in the tanks
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Performance demonstration requirements for eddy current steam generator tube inspection
This paper describes the methodology used for developing performance demonstration tests for steam generator tube eddy current (ET) inspection systems. The methodology is based on statistical design principles. Implementation of a performance demonstration test based on these design principles will help to ensure that field inspection systems have a high probability of detecting and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented. Probability of detection and flaw sizing tests are described
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Performance demonstration tests for eddy current inspection of steam generator tubing
This report describes the methodology and results for development of performance demonstration tests for eddy current (ET) inspection of steam generator tubes. Statistical test design principles were used to develop the performance demonstration tests. Thresholds on ET system inspection performance were selected to ensure that field inspection systems would have a high probability of detecting and and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented in detail. Statistical test design calculations for probability of detection and flaw sizing tests are described. A recommended performance demonstration test based on the design calculations is presented. A computer program for grading the probability of detection portion of the performance demonstration test is given
PCI fuel failure analysis: a report on a cooperative program undertaken by Pacific Northwest Laboratory and Chalk River Nuclear Laboratories.
Reactor fuel failure data sets in the form of initial power (P/sub i/), final power (P/sub f/), transient increase in power (..delta..P), and burnup (Bu) were obtained for pressurized heavy water reactors (PHWRs), boiling water reactors (BWRs), and pressurized water reactors (PWRs). These data sets were evaluated and used as the basis for developing two predictive fuel failure models, a graphical concept called the PCI-OGRAM, and a nonlinear regression based model called PROFIT. The PCI-OGRAM is an extension of the FUELOGRAM developed by AECL. It is based on a critical threshold concept for stress dependent stress corrosion cracking. The PROFIT model, developed at Pacific Northwest Laboratory, is the result of applying standard statistical regression methods to the available PCI fuel failure data and an analysis of the environmental and strain rate dependent stress-strain properties of the Zircaloy cladding