Download or read book Challenges and Methodology for Safety Analysis of a High level Waste Tank with Large Periodic Releases of Flammable Gas written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-11 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radioactive Waste Management written by and published by . This book was released on 1981 with total page 726 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Probabilistic Safety Assessment for Hanford High level Waste Tank 241 SY 101 written by and published by . This book was released on 1994 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt: Los Alamos National Laboratory (Los Alamos) is performing a comprehensive probabilistic safety assessment (PSA), which will include consideration of external events for the 18 tank farms at the Hanford Site. This effort is sponsored by the Department of Energy (DOE/EM, EM-36). Even though the methodology described herein will be applied to the entire tank farm, this report focuses only on the risk from the weapons-production wastes stored in tank number 241-SY-101, commonly known as Tank 101-SY, as configured in December 1992. This tank, which periodically releases ({open_quotes}burps{close_quotes}) a gaseous mixture of hydrogen, nitrous oxide, ammonia, and nitrogen, was analyzed first because of public safety concerns associated with the potential for release of radioactive tank contents should this gas mixture be ignited during one of the burps. In an effort to mitigate the burping phenomenon, an experiment is being conducted in which a large pump has been inserted into the tank to determine if pump-induced circulation of the tank contents will promote a slow, controlled release of the gases. At the Hanford Site there are 177 underground tanks in 18 separate tank farms containing accumulated liquid/sludge/salt cake radioactive wastes from 50 yr of weapons materials production activities. The total waste volume is about 60 million gal., which contains approximately 120 million Ci of radioactivity.

Download or read book Flammable Gas Tank Safety Program written by and published by . This book was released on 1998 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several Hanford waste tanks have been observed to exhibit periodic releases of significant quantities of flammable gases. Because potential safety issues have been identified with this type of waste behavior, applicable tanks were equipped with instrumentation offering the capability to continuously monitor gases released from them. This document was written to cover three primary areas: (1) describe the current technical basis for requiring flammable gas monitoring, (2) update the technical basis to include knowledge gained from monitoring the tanks over the last three years, (3) provide the criteria for removal of Standard Hydrogen Monitoring System(s) (SHMS) from a waste tank or termination of other flammable gas monitoring activities in the Hanford Tank farms.

Download or read book A Summary Description of the Flammable Gas Tank Safety Program written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Radioactive liquid waste may produce hydrogen as result of the interaction of gamma radiation and water. If the waste contains organic chelating agents, additional hydrogen as well as nitrous oxide and ammonia may be produced by thermal and radiolytic decomposition of these organics. Several high-level radioactive liquid waste storage tanks, located underground at the Hanford Site in Washington State, are on a Flammable Gas Watch List. Some contain waste that produces and retains gases until large quantities of gas are released rapidly to the tank vapor space. Tanks nearly-filled to capacity have relatively little vapor space; therefore if the waste suddenly releases a large amount of hydrogen and nitrous oxide, a flammable gas mixture could result. The most notable example of a Hanford waste tank with a flammable gas problem is tank 241-SY-101. Upon occasion waste stored in this tank has released enough flammable gas to burn if an ignition source had been present inside of the tank. Several, other Hanford waste tanks exhibit similar behavior although to a lesser magnitude. Because this behavior was hot adequately-addressed in safety analysis reports for the Hanford Tank Farms, an unreviewed safety question was declared, and in 1990 the Flammable Gas Tank Safety Program was established to address this problem. The purposes of the program are a follows: (1) Provide safety documents to fill gaps in the safety analysis reports, and (2) Resolve the safety issue by acquiring knowledge about gas retention and release from radioactive liquid waste and developing mitigation technology. This document provides the general logic and work activities required to resolve the unreviewed safety question and the safety issue of flammable gas mixtures in radioactive liquid waste storage tanks.

Download or read book SAFETY ANALYSIS APPROACH TO TANK 241 SY 101 REMEDIATION ACTIVITIES written by and published by . This book was released on 2000 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: An Unreviewed Safety Question was declared related to the unexplained waste surface level growth in high-level radioactive waste storage Tank 241-SY-101 at the Hanford Site in Richland, Washington. Because the waste surface level in Tank 241-SY-101 was growing in a manner inconsistent with previous behavior, the following issues of concern were recognized: (1) The continually rising surface level had the potential to reach physical encumbrances or limits within the tank (e.g., instrumentation, cameras, established Authorization Basis limits, and the double containment boundary) and the potential to significantly change the consequences of previously analyzed accidents (e.g., flammable gas deflagrations). (2) The presence of new hazards because of significant quantities of flammable gas retained in the crust (e.g., crust collapse gas-release events). (3) The potential to inhibit information gathering related to the existing hazards in the tank (e.g., unable to determine surface level to assess the potential for large gas releases). In response to this situation, a Contractor Project Team, which included Department of Energy representation, was formed to constructively address the issue. The team was responsible for developing and evaluating remediation options and executing the chosen option for remediating the surface level rise issue for Tank 241-SY-101. From an Authorization Basis perspective, the following important aspects will be discussed in this paper: (1) The integrated nature of the Project Team. The team consisted of all the organizations necessary to ensure that the time available to remediate Tank 241-SY-101 was effectively used. Most notable is the connectivity of the Nuclear Safety & Licensing organization with the Engineering, Design, and Operations organizations. (2) The ability of the safety analysis support to adjust to and address evolving Project Team goals and dynamic tank conditions. (3) Due to the urgency to mitigate this developing issue, supplemental controls to ensure safety during remediation operations and activities were developed and approved at the Contractor level with DOE cognizance through their participation as an integral part of the Project Team. This approach was selected as the most expedient to meet the aggressive project schedule and changing tank conditions. This project has been successful in meeting established goals because of the effectiveness of an integrated project team that included Nuclear Safety & Licensing at the start, the integral involvement of DOE during each phase of the project, and the ability of the Contractor to develop, approve, and implement the supplemental controls necessary to safely perform operations and activities.

Download or read book New Challenges in the Safety Analysis of DOE s High level Waste Tanks written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Approximate reasoning based Method for Screening High level Waste Tanks for Flammable Gas written by and published by . This book was released on 1998 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The in situ retention of flammable gas produced by radiolysis and thermal decomposition in high-level waste can pose a safety problem if the gases are released episodically into the dome space of a storage tank. Screening efforts at Hanford have been directed at identifying tanks in which this situation could exist. Problems encountered in screening motivated an effort to develop an improved screening methodology. Approximate reasoning (AR) is a formalism designed to emulate the kinds of complex judgments made by subject matter experts. It uses inductive logic structures to build a sequence of forward-chaining inferences about a subject. AR models incorporate natural language expressions known as linguistic variables to represent evidence. The use of fuzzy sets to represent these variables mathematically makes it practical to evaluate quantitative and qualitative information consistently. The authors performed a pilot study to investigate the utility of AR for flammable gas screening. They found that the effort to implement such a model was acceptable and that computational requirements were reasonable. The preliminary results showed that important judgments about the validity of observational data and the predictive power of models could be made. These results give new insights into the problems observed in previous screening efforts.

Download or read book Approach for Tank Safety Characterization of Hanford Site Waste written by and published by . This book was released on 1995 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall approach and associated technical basis for characterizing Hanford Site waste to help identify and resolve Waste Tank Safety Program safety issues has been summarized. The safety issues include flammable gas, noxious vapors, organic solvents, condensed-phase exothermic reactions (ferrocyanide and organic complexants), criticality, high heat, and safety screening. For the safety issues involving chemical reactions (i.e., flammable gas, organic solvents, ferrocyanide, and organic complexants), the approach to safety characterization is based on the fact that rapid exothermic reactions cannot occur if either fuel, oxidizer, or temperature (initiators) is not sufficient or controlled. The approach to characterization has been influenced by the progress made since mid-1993: (1) completion of safety analyses on ferrocyanide, criticality, organic solvent in tank 241-C-103, and sludge dryout. (2) successful mitigation of tank 241-SY-101; (3) demonstration of waste aging in laboratory experiments and from waste sampling, and (4) increased understanding of the information that can be obtained from headspace sampling. Headspace vapor sampling is being used to confirm that flammable gas does not accumulate in the single-shell tanks, and to determine whether organic solvents are present. The headspaces of tanks that may contain significant quantities of flammable gas will be monitored continuously using standard hydrogen monitors. For the noxious vapors safety issue, characterization will consist of headspace vapor sampling of most of the Hanford Site waste tanks. Sampling specifically for criticality is not required to confirm interim safe storage; however, analyses for fissile material will be conducted as waste samples are obtained for other reasons. High-heat tanks will be identified through temperature monitoring coupled with thermal analyses.

Download or read book A Safety Assessment of Rotary Mode Core Sampling in Flammable Gas Single Shell Tanks written by and published by . This book was released on 1996 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: This safety assessment (SA) addresses each of the required elements associated with the installation, operation, and removal of a rotary-mode core sampling (RMCS) device in flammable-gas single-shell tanks (SSTs). The RMCS operations are needed in order to retrieve waste samples from SSTs with hard layers of waste for which push-mode sampling is not adequate for sampling. In this SA, potential hazards associated with the proposed action were identified and evaluated systematically. Several potential accident cases that could result in radiological or toxicological gas releases were identified and analyzed and their consequences assessed. Administrative controls, procedures and design changes required to eliminate or reduce the potential of hazards were identified. The accidents were analyzed under nine categories, four of which were burn scenarios. In SSTS, burn accidents result in unacceptable consequences because of a potential dome collapse. The accidents in which an aboveground burn propagates into the dome space were shown to be in the ''beyond extremely unlikely'' frequency category. Given the unknown nature of the gas-release behavior in the SSTS, a number of design changes and administrative controls were implemented to achieve these low frequencies. Likewise, drill string fires and dome space fires were shown to be very low frequency accidents by taking credit for the design changes, controls, and available experimental and analytical data. However, a number of Bureau of Mines (BOM) tests must be completed before some of the burn accidents can be dismissed with high confidence. Under the category of waste fires, the possibility of igniting the entrapped gases and the waste itself were analyzed. Experiments are being conducted at the BOM to demonstrate that the drill bit is not capable of igniting the trapped gas in the waste. Laboratory testing and thermal analysis demonstrated that, under normal operating conditions, the drill bit will not create high enough temperatures to initiate a propagating reaction in the waste. However, system failure that coincides in a waste layer with high organic content and low moisture may initiate an exothermic reaction in the waste. Consequently, a conservative approach based on the current state of the knowledge resulted in limiting the drilling process to a subset of the flammable-gas tanks. Accidents from the chemical reactions and criticality category are shown to result in acceptable risk. A number of accidents are shown to potentially result in containment (tank liner) breach below the waste level. Mitigative features are provided for these accidents. Gas-release events without burn also are analyzed, and radiological and toxicological consequences are shown to be within risk guidelines. Finally, the consequences of potential spills are shown to be within the risk guidelines.

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1995 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hanford Tank Farm Interim Storage Phase Probabilistic Risk Assessment Outline written by and published by . This book was released on 1994 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report is the second in a series examining the risks for the high level waste (HLW) storage facilities at the Hanford Site. The first phase of the HTF PSA effort addressed risks from Tank 101-SY, only. Tank 101-SY was selected as the initial focus of the PSA because of its propensity to periodically release (burp) a mixture of flammable and toxic gases. This report expands the evaluation of Tank 101-SY to all 177 storage tanks. The 177 tanks are arranged into 18 farms and contain the HLW accumulated over 50 years of weapons material production work. A centerpiece of the remediation activity is the effort toward developing a permanent method for disposing of the HLW tank's highly radioactive contents. One approach to risk based prioritization is to perform a PSA for the whole HLW tank farm complex to identify the highest risk tanks so that remediation planners and managers will have a more rational basis for allocating limited funds to the more critical areas. Section 3 presents the qualitative identification of generic initiators that could threaten to produce releases from one or more tanks. In section 4 a detailed accident sequence model is developed for each initiating event group. Section 5 defines the release categories to which the scenarios are assigned in the accident sequence model and presents analyses of the airborne and liquid source terms resulting from different release scenarios. The conditional consequences measured by worker or public exposure to radionuclides or hazardous chemicals and economic costs of cleanup and repair are analyzed in section 6. The results from all the previous sections are integrated to produce unconditional risk curves in frequency of exceedance format.

Download or read book High heat Tank Safety Issues Evaluation written by and published by . This book was released on 1993 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subsection (b) of Public Law 101-510, Section 3137, {open_quotes}Safety Measures for Waste Tanks at Hanford Nuclear Reservation{close_quotes} (PL 101-510), requires the Secretary of Energy to {open_quotes}identify those tanks that may have a serious potential for release of high-level waste due to uncontrolled increase in temperature or pressure{close_quotes}. One of the tanks that has been identified to meet this criteria is single-shell tank (SST) 241-C-106 (Wilson and Reep 1991). This report presents the results of an evaluation of the safety issue associated with tank 241-C-106: the continued cooling required for high heat generation in tank 241-C-106. If tank 241-C-106 should start leaking, continued addition of water for cooling could possibly increase the amount of leakage to the soil column. In turn, if the current methods of cooling tank 241-C-106 are stopped, the sludge temperatures may exceed established temperature limits, the long term structural integrity of the tank liner and concrete would be jeopardized, leading to an unacceptable release to the environment. Among other conclusions, this evaluation has determined that tank 241-C-106 contains enough heat generating wastes to justify retaining this tank on the list {open_quotes}Single-Shell Tanks With High Heat Loads (>40,000 Btu/H){close_quotes} and that to confirm the structural integrity needed for the retrieval of the contents of tank 241-C-106, an updated structural analysis and thermal analysis need to be conducted. Other findings of this evaluation are also reported.

Download or read book Flammable Gas Release Estimates for Modified Sluicing Retrieval of Waste from Selected Hanford Single Shell Tanks written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The high-level radioactive wastes in many single-shell tanks (SSTs) at the Hanford Site are to be retrieved by a modified sluicing method that uses water jets to dissolve the water-soluble waste and mobilize the water-insoluble waste. Retrieval operations will liberate any waste gases trapped in the wetted solid waste matrix, and these gases will be released into the tank headspaces. Because the trapped gases include the flammable species hydrogen, methane, and ammonia, a concern exists that a flammable mixture could be formed in the tank headspaces. This report combines conservative retained gas inventory estimates and tank data with anticipated waste retrieval rates to estimate the potential headspace flammability of selected SSTs during modified sluicing waste retrieval operations. Considered here are nine of the 12 tanks from the 241-S tank farm (241-S-107, 241-S-111, and 241-S 112 are not considered) and Tank 241-U-107. This report is intended to support the specification of process controls that ensure flammable conditions do not develop in the tank headspaces. Consequently, the physical scenarios considered, the models developed to estimate retained gas releases and the tank headspace compositions under these scenarios, and the model input data are intended to conservatively assess the potential to reach headspace flammability. The analyses are intended to address worst-case conditions and establish reasonable upper bounds on the achievable flammability of the tank headspaces. Flammable retained gas inventories, for example, are based on the 95th percentile developed by Barker and Hedengren (2003), giving 95% confidence that actual inventories are smaller than those used in the calculations. Gas releases and headspace flammability were evaluated for three general scenarios: a very aggressive dissolution and erosion of saltcake waste by water jets impinging on the waste surface, the drainage of interstitial liquids from saltcake during a shutdown of the retrieval process, and the dissolution of saltcake by unsaturated liquids during a shutdown of the retrieval process. The simple model of waste retrieval using the modified sluicing approach indicated that the flammable gas headspace concentrations can rapidly approach the action level of 25% of the lower flammability limit (LFL) when the tank is passively ventilated. While it is not necessary to use the portable exhauster to maintain the headspace hydrogen concentration below this action level, retrieval rates would probably be limited by the slow removal of flammable gases by passive ventilation. It was determined that using a portable exhauster anywhere in the assumed operating range of 270 to 475 cfm would prevent the headspaces from reaching the 25% of LFL action level even if the water jets are very effective at eroding the saltcake. Specific guidelines are developed to ensure that, in the event of a catastrophic loss of the retrieval pump and portable exhauster, headspace flammability will not reach the LFL. This report is Revision 1 of PNNL-14271. This revision expands the analysis of interstitial liquid drainage-induced gas releases to address a general retrieval scenario (the previous version of this report assumed a center-out retrieval approach and conditions). Tank waste conditions (waste volumes, interstitial liquid levels, temperatures, retained gas void fractions, etc.) have also been updated from the previous version.

Download or read book Deflagration Studies on Waste Tank 101 SY written by and published by . This book was released on 1991 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Waste slurries produced during the recovery of plutonium and uranium from irradiated fuel are stored in underground storage tanks. While a variety of waste types have been generated, of particular concern are the wastes stored in Tank 101-SY. A slurry growth-gas evolution cycle has been observed since 1981. The waste consists of a thick slurry, consisting of a solution high in NaOH, NaNO3, NaAlO2, dissolved organic complexants (EDTA, HEDTA, NTA, and degradation products), other salts (sulfates and phosphates), and radionuclides (primarily cesium and strontium). During a gas release the major gaseous species identified include: hydrogen and nitrous oxide (N2O). Significant amounts of nitrogen may also be present. Traces of ammonia, carbon oxides, and other nitrogen oxides are also detected. Air and water vapor are also present in the tank vapor space. The purpose of the deflagration study is to determine risks of the hydrogen, nitrous oxide, nitrogen, and oxygen system. To be determined are pressure and temperature as a function of composition of reacting gases and the concentration of gases before and after the combustion event. Analyses of gases after the combustion event will be restricted to those tests that had an initial concentration of (less-than or equal to)8% hydrogen. This information will be used to evaluate safety issues related to periodic slurry growth and flammable gas releases from Tank 101-SY. the conditions to be evaluated will simulate gases in the vapor space above the salt cake as well as gases that potentially are trapped in pockets within/under the waste. The deflagration study will relate experimental laboratory results to conditions in the existing tanks.

Download or read book Energy and Water Development Appropriations for 2015 National Nuclear Security Administration energy weapons activities defense nuclear nonproliferation and naval reactors written by United States. Congress. House. Committee on Appropriations. Subcommittee on Energy and Water Development and published by . This book was released on 2014 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: