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Criticality Safety Of High Level Tank Waste
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Book Synopsis Criticality Safety of High-level Tank Waste by :
Download or read book Criticality Safety of High-level Tank Waste written by and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radioactive waste containing low concentrations of fissile isotopes is stored in underground storage tanks on the Hanford Site in Washington State. The goal of criticality safety is to ensure that this waste remains subcritical into the indefinite future without supervision. A large ratio of solids to plutonium provides an effective way of ensuring a low plutonium concentration. Since the first waste discharge, a program of audits and appraisals has ensured that operations are conducted according to limits and controls applied to them. In addition, a program of surveillance and characterization maintains watch over waste after discharge.
Book Synopsis Criticality Safety Evaluation of Hanford Site High Level Waste Storage Tanks by :
Download or read book Criticality Safety Evaluation of Hanford Site High Level Waste Storage Tanks written by and published by . This book was released on 2000 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: This criticality safety evaluation covers operations for waste in underground storage tanks at the high-level waste tank farms on the Hanford site. This evaluation provides the bases for criticality safety limits and controls to govern receipt, transfer, and long-term storage of tank waste. Justification is provided that a nuclear criticality accident cannot occur for tank farms operations, based on current fissile material and operating conditions.
Book Synopsis Nuclear Criticality Safety Review of Hanford High-level Radioactive Waste Tank Farms by : John M. Clark
Download or read book Nuclear Criticality Safety Review of Hanford High-level Radioactive Waste Tank Farms written by John M. Clark and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Resolution of the Nuclear Criticality Safety Issue for the Hanford Site High-level Waste Tanks by :
Download or read book Resolution of the Nuclear Criticality Safety Issue for the Hanford Site High-level Waste Tanks written by and published by . This book was released on 1997 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the approach used to resolve the Nuclear Criticality Safety Issue for the Hanford Site high-level waste tanks. Although operational controls have been in place at the Hanford Site throughout its operating life to minimize the amount of fissile material discarded as waste, estimates of the total amount of plutonium that entered the waste tanks range from 500 to 1,000 kg. Nuclear criticality safety concerns were heightened in 1991 based on a review of waste analysis results and a subsequent U.S. Department of Energy 1399 review of the nuclear criticality program. Although the DOE review team concluded that there was no imminent risk of a criticality at the Hanford Site tank farms, the team also stated its concern regarding the lack of definitive knowledge of the fissile material inventory and distribution within the waste tanks and the lack of sufficient management support for the overall criticality safety program. An in-depth technical review of the nuclear criticality safety of the waste tanks was conducted to develop a defensible technical basis to ensure that waste tanks are subcritical. The review covered all relevant aspects of nuclear criticality safety including neutronics and chemical and physical phenomena of the waste form under aging waste conditions as well as during routine waste management operations. This paper provides a review of the technical basis to support the conclusion that given current plutonium inventories and operating conditions, a nuclear criticality is incredible. The DOE has been requested to close the Nuclear Criticality Safety Issue. The Defense Nuclear Facilities Safety Board is currently reviewing the technicalbasis.
Book Synopsis Characterization Strategy Report for the Criticality Safety Issue by :
Download or read book Characterization Strategy Report for the Criticality Safety Issue written by and published by . This book was released on 1997 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-level radioactive waste from nuclear fuels processing is stored in underground waste storage tanks located in the tank farms on the Hanford Site. Waste in tank storage contains low concentrations of fissile isotopes, primarily U-235 and Pu-239. The composition and the distribution of the waste components within the storage environment is highly complex and not subject to easy investigation. An important safety concern is the preclusion of a self-sustaining neutron chain reaction, also known as a nuclear criticality. A thorough technical evaluation of processes, phenomena, and conditions is required to make sure that subcriticality will be ensured for both current and future tank operations. Subcriticality limits must be based on considerations of tank processes and take into account all chemical and geometrical phenomena that are occurring in the tanks. The important chemical and physical phenomena are those capable of influencing the mixing of fissile material and neutron absorbers such that the degree of subcriticality could be adversely impacted. This report describes a logical approach to resolving the criticality safety issues in the Hanford waste tanks. The approach uses a structured logic diagram (SLD) to identify the characterization needed to quantify risk. The scope of this section of the report is limited to those branches of logic needed to quantify the risk associated with a criticality event occurring. The process is linked to a conceptual model that depicts key modes of failure which are linked to the SLD. Data that are needed include adequate knowledge of the chemical and geometric form of the materials of interest. This information is used to determine how much energy the waste would release in the various domains of the tank, the toxicity of the region associated with a criticality event, and the probability of the initiating criticality event.
Book Synopsis Upgrade Activities for the Criticality Safety Program of Hanford High-Level Radioactive Waste Tank Farm by : T. S. Vail
Download or read book Upgrade Activities for the Criticality Safety Program of Hanford High-Level Radioactive Waste Tank Farm written by T. S. Vail and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book CSER 94-004 written by and published by . This book was released on 1994 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This criticality safety evaluation covers double-shell waste storage tanks (DSTs), double-contained receiver tanks (DCRTs), vault tanks, and the 242-A Evaporator located in the High Level Waste (HLW) Tank Farms on the Hanford Site. Limits and controls are specified and the basis for ensuring criticality safety is discussed. A minimum limit of 1,000 is placed upon the solids/plutonium mass ratio in incoming waste. The average solids/Pu mass ratio over all waste in tank farms is estimated to be about 74,500, about 150 times larger than required to assure subcriticality in homogeneous waste. PFP waste in Tank-102-SY has an estimated solids/Pu mass ratio of 10,000. Subcriticality is assured whenever the plutonium concentration is less than 2.6 g. The median reported plutonium concentration for 200 samples of waste solids is about 0.01 g (0.038 g/gal). A surveillance program is proposed to increase the knowledge of the waste and provide added assurance of the high degree of subcriticality.
Book Synopsis Criticality Parameters for Tank Waste Evaluation by :
Download or read book Criticality Parameters for Tank Waste Evaluation written by and published by . This book was released on 1997 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear criticality parameters were developed as a basis for evaluating criticality safety for waste stored in the high-level waste tank farms on the Hanford Site in Washington State. The plutonium critical concentration and critical mass were calculated using a conservative waste model (CWM). The primary requirement of a CWM is that it have a lower neutron absorption than any actual waste. Graphs are provided of the critical mass as a function of plutonium concentration for spheres and for uniform slab layers in a 22.9-m-diameter tank. Minimum subcritical absorber-to-plutonium mass rates were calculated for waste components selected for their relative abundance and neutron absorption capacity. Comparison of measured absorber-to-plutonium mass ratios in their corresponding subcritical limit mass ratios provides a means of assessing whether criticality is possible for waste of the measured composition. A comparison is made between the plutonium critical concentrations in CWM solids and in a postulated real waste. This comparison shows that the actual critical parameters are likely to be significantly larger than those obtained using the CWM, thus providing confidence that the margin of safety obtained to the criticality safety evaluation is conservative.
Book Synopsis Criticality Safety Evaluation of Hanford Tank Farms Facility by :
Download or read book Criticality Safety Evaluation of Hanford Tank Farms Facility written by and published by . This book was released on 2000 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Data and calculations from previous criticality safety evaluations and analyses were used to evaluate criticality safety for the entire Tank Farms facility to support the continued waste storage mission. This criticality safety evaluation concludes that a criticality accident at the Tank Farms facility is an incredible event due to the existing form (chemistry) and distribution (neutron absorbers) of tank waste. Limits and controls for receipt of waste from other facilities and maintenance of tank waste condition are set forth to maintain the margin subcriticality in tank waste.
Book Synopsis Criticality Safety Analysis of Hanford Waste Tank 241-101-SY. by :
Download or read book Criticality Safety Analysis of Hanford Waste Tank 241-101-SY. written by and published by . This book was released on 1993 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of a safety assessment for proposed pump mixing operations to mitigate episodic gas releases in Tank 241-101-SY at the Hanford Site, Richland, Washington, a criticality safety analysis was made using the Sn transport code ONEDANT. The tank contains approximately one million gallons of waste and an estimated 910 G of plutonium. the criticality analysis considers reconfiguration and underestimation of plutonium content. The results indicate that Tank SY-101 does not present a criticality hazard. These methods are also used in criticality analyses of other Hanford tanks.
Book Synopsis Tank Waste Remediation System Nuclear Criticality Safety Program Management Review by :
Download or read book Tank Waste Remediation System Nuclear Criticality Safety Program Management Review written by and published by . This book was released on 1999 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document provides the results of an internal management review of the Tank Waste Remediation System (TWRS) criticality safety program, performed in advance of the DOE/RL assessment for closure of the TWRS Nuclear Criticality Safety Issue, March 1994. Resolution of the safety issue was identified as Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) Milestone M-40-12, due September 1999.
Book Synopsis Nuclear Criticality Safety Evaluation -- DWPF Late Wash Facility, Salt Process Cell and Chemical Process Cell by :
Download or read book Nuclear Criticality Safety Evaluation -- DWPF Late Wash Facility, Salt Process Cell and Chemical Process Cell written by and published by . This book was released on 1994 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Savannah River Site (SRS) High Level Nuclear Waste will be vitrified in the Defense Waste Processing Facility (DWPF) for long term storage and disposal. This is a nuclear criticality safety evaluation for the Late Wash Facility (LWF), the Salt Processing Cell (SPC) and the Chemical Processing Cell (CPC). of the DWPF. Waste salt solution is processed in the Tank Farm In-Tank Precipitation (ITP) process and is then further washed in the DWPF Late Wash Facility (LWF) before it is fed to the DWPF Salt Processing Cell. In the Salt Processing Cell the precipitate slurry is processed in the Precipitate Reactor (PR) and the resultant Precipitate Hydrolysis Aqueous (PHA) produce is combined with the sludge feed and frit in the DWPF Chemical Process Cell to produce a melter feed. The waste is finally immobilized in the Melt Cell. Material in the Tank Farm and the ITP and Extended Sludge processes have been shown to be safe against a nuclear criticality by others. The precipitate slurry feed from ITP and the first six batches of sludge feed are safe against a nuclear criticality and this evaluation demonstrates that the processes in the LWF, the SPC and the CPC do not alter the characteristics of the materials to compromise safety.
Download or read book Environmental Assessment written by and published by . This book was released on 1994 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: The US Department of Energy (DOE) needs to take action in the near-term, to accelerate resolution of waste tank safety issues at the Hanford Site near the City of Richland, Washington, and reduce the risks associated with operations and management of the waste tanks. The DOE has conducted nuclear waste management operations at the Hanford Site for nearly 50 years. Operations have included storage of high-level nuclear waste in 177 underground storage tanks (UST), both in single-shell tank (SST) and double-shell tank configurations. Many of the tanks, and the equipment needed to operate them, are deteriorated. Sixty-seven SSTs are presumed to have leaked a total approximately 3,800,000 liters (1 million gallons) of radioactive waste to the soil. Safety issues associated with the waste have been identified, and include (1) flammable gas generation and episodic release; (2) ferrocyanide-containing wastes; (3) a floating organic solvent layer in Tank 241-C-103; (4) nuclear criticality; (5) toxic vapors; (6) infrastructure upgrades; and (7) interim stabilization of SSTs. Initial actions have been taken in all of these areas; however, much work remains before a full understanding of the tank waste behavior is achieved. The DOE needs to accelerate the resolution of tank safety concerns to reduce the risk of an unanticipated radioactive or chemical release to the environment, while continuing to manage the wastes safely.
Book Synopsis Tank Waste Remediation System Nuclear Criticality Safety Inspection and Assessment Plan by :
Download or read book Tank Waste Remediation System Nuclear Criticality Safety Inspection and Assessment Plan written by and published by . This book was released on 1999 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: This plan provides a management approved procedure for inspections and assessments of sufficient depth to validate that the Tank Waste Remediation System (TWRS) facility complies with the requirements of the Project Hanford criticality safety program, NHF-PRO-334, ''Criticality Safety General, Requirements''.
Download or read book Radioactive Waste Management written by and published by . This book was released on 1981 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Savannah River Site, High-level Waste Tank Closure by :
Download or read book Savannah River Site, High-level Waste Tank Closure written by and published by . This book was released on 2002 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Criticality Safety Assessment of Tank 241-C-106 Remediation by :
Download or read book Criticality Safety Assessment of Tank 241-C-106 Remediation written by and published by . This book was released on 1996 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: A criticality safety assessment was performed in support of Project 320 for the retrieval of waste from tank 241-C-106 to tank 241-AY-102. The assessment was performed by a multi-disciplined team consisting of expertise covering the range of nuclear engineering, plutonium and nuclear waste chemistry, and physical mixing hydraulics. Technical analysis was performed to evaluate the physical and chemical behavior of fissile material in neutralized Hanford waste as well as modeling of the fluid dynamics for the retrieval activity. The team has not found evidence of any credible mechanism to attain neutronic criticality in either tank and has concluded that a criticality accident is incredible.
