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Description of the Material Balance Model and Spreadsheet for Salt Dissolution

Description: The model employed to estimate the amount of inhibitors necessary for bearing water and dissolution water during the salt dissolution process is described. This model was inputed on a spreadsheet which allowed many different case studies to be performed. This memo describes the assumptions and equations which are used in the model, and documents the input and output cells of the spreadsheet. Two case studies are shown as examples of how the model may be employed.
Date: October 12, 1994
Creator: Wiersma, B.J.
Partner: UNT Libraries Government Documents Department

Structural Dimensions, Fabrication, Materials, and Operational History for Types I and II Waste Tanks

Description: Radioactive waste is confined in 48 underground storage tanks at the Savannah River Site. The waste will eventually be processed and transferred to other site facilities for stabilization. Based on waste removal and processing schedules, many of the tanks, including those with flaws and/or defects, will be required to be in service for another 15 to 20 years. Until the waste is removed from storage, transferred, and processed, the materials and structures of the tanks must maintain a confinement function by providing a leak-tight barrier to the environment and by maintaining acceptable structural stability during design basis event which include loading from both normal service and abnormal conditions.
Date: August 16, 2000
Creator: Wiersma, B.J.
Partner: UNT Libraries Government Documents Department

Determination of Temperature Limits for Radioactive Waste Tanks

Description: This document provides a systematic approach for determining the temperature limits for a tank given that the supernate concentration is known, or for ''dry'' tanks, given that the supernate concentration from the last sample of free supernate that was collected is known. A decision tree was developed to provide the logic for the temperature limit determination.
Date: August 31, 1999
Creator: Wiersma, B.J.
Partner: UNT Libraries Government Documents Department

Corrosion Testing of Carbon Steel in Acid Cleaning Solutions

Description: High level waste is stored in carbon steel tanks at the Savannah River Site (SRS). The site is currently in the process of waste removal from, and ultimately closure of, these tanks. One of the most time consuming steps in the waste removal process is cleaning the sludge heel from the bottom of the tanks to an acceptable residual quantity. The sludge consists primarily of metal oxides that formed after waste from the canyons was neutralized with sodium hydroxide. Since the canyon waste was originally a nitric acid solution, this acid is a prime candidate for sludge heel dissolution.
Date: December 6, 2002
Creator: Wiersma, B.J.
Partner: UNT Libraries Government Documents Department

Investigation of the corrosion behavior of cooling coil material in a simulated concrete environment

Description: Pitting corrosion of the cooling coils embedded in the concrete roof of the waste tanks is one of the suspected causes of the recent cooling coil failures. Cyclic polarization tests were conducted to predict the threshold chloride level above which pitting would initiate. The threshold chloride level was determined to be 9000 ppM. Although these tests predict the electrochemical or corrosion behavior of the metal, they may not predict the severity of attack. Further tests which investigate the effect of the permeability of the concrete matrix on the transport of water and oxygen to the metal surface are planned to assess the severity of attack.
Date: February 1, 1993
Creator: Wiersma, B.J.
Partner: UNT Libraries Government Documents Department

Measurement of the ductile to brittle transition temperature for waste tank cooling coils

Description: Charpy impact tests were conducted on ASTM A106 carbon steel archived from SRS waste tanks to determine the susceptibility of the cooling coils to brittle fracture during a seismic event. The highest ductile to brittle transition temperature measured was [minus]5[degree]F and, with the addition of a 30[degree]F safety factor, the minimum safe operating temperature was determined to be 25[degree]F. Calculations also showed that a pre-existing circumferential flaw that is 2.2in. long would be necessary to initiate brittle fracture of the pipe. These results demonstrate that the pipes will not be susceptible to brittle fracture if the cooling water inlet temperature is lowered to 50[degree]F. Visual observation of the inner and outer walls of the pipe showed no localized attack or significant wall thinning. A 100--200 micron zinc coating is probably the reason for the lack of corrosion. A build-up of zinc slag occurred at pipe fittings where the weld had burned through. Although no attack was observed, the slag created several crevices which have the potential to trap the chromated water and initiate localized attack.
Date: September 1, 1992
Creator: Wiersma, B.J.
Partner: UNT Libraries Government Documents Department

Corrosion Control Measures For Liquid Radioactive Waste Storage Tanks At The Savannah River Site

Description: The Savannah River Site has stored radioactive wastes in large, underground, carbon steel tanks for approximately 60 years. An assessment of potential degradation mechanisms determined that the tanks may be vulnerable to nitrate- induced pitting corrosion and stress corrosion cracking. Controls on the solution chemistry and temperature of the wastes are in place to mitigate these mechanisms. These controls are based upon a series of experiments performed using simulated solutions on materials used for construction of the tanks. The technical bases and evolution of these controls is presented in this paper.
Date: November 27, 2012
Creator: Wiersma, B. J. & Subramanian, K. H.
Partner: UNT Libraries Government Documents Department

Synergistic Inhibitors for Dilute High-Level Radioactive Waste

Description: Cyclic potentiodynamic polarization scans were conducted to determine the effectiveness of various combinations of anodic inhibitors in the prevention of pitting in carbon steel exposed to dilute radioactive waste. Chromate, molybdate, and phosphate were investigated as replacements for nitrite, whose effective concentrations are incompatible with the waste vitrification process. The polarization scans were performed in non-radioactive waste simulants. Their results showed that acceptable combinations of phosphate with chromate and phosphate with molybdate effectively prevented pitting corrosion. Chromate with molybdate could not replace nitrite.
Date: November 1, 1995
Creator: Wiersma, B.J. & Zapp, P.E.
Partner: UNT Libraries Government Documents Department

Laboratory simulation of salt dissolution during waste removal

Description: Laboratory experiments were performed to support the field demonstration of improved techniques for salt dissolution in waste tanks at the Savannah River Site. The tests were designed to investigate three density driven techniques for salt dissolution: (1) Drain-Add-Sit-Remove, (2) Modified Density Gradient, and (3) Continuous Salt Mining. Salt dissolution was observed to be a very rapid process as salt solutions with densities between 1.38-1.4 were frequently removed. Slower addition and removal rates and locating the outlet line at deeper levels below the top of the saltcake provided the best contact between the dissolution water and the saltcake. It was observed that dissolution with 1 M sodium hydroxide solution resulted in salt solutions that were within the current inhibitor requirements for the prevention of stress corrosion cracking. This result was independent of the density driven technique. However, if inhibited water (0.01 M sodium hydroxide and 0.011 M sodium nitrite) was utilized, the salt solutions were frequently outside the inhibitor requirements. Corrosion testing at conditions similar to the environments expected during waste removal was recommended.
Date: January 1, 1997
Creator: Wiersma, B.J. & Parish, W.R.
Partner: UNT Libraries Government Documents Department

Limits on Annulus Air Outages in Types 1, 2, and 3 Waste Tanks

Description: An evaluation was performed on the impact of abnormal air flow conditions on the structural integrity of Types 1, 2, and 3 waste tanks. Warm, dry air in the annular space is necessary to preclude low temperature embrittlement and corrosive conditions for the carbon steel materials. For Type 1 and 2 tanks the annulus air system should be repaired within a month to minimize the potential for low temperature embrittlement and corrosive conditions, for Tanks 29-34, which are Type 3 tanks, it is recommended that the system be repaired within two months to minimize the potential for low temperature embrittlement. For all other Type 3 tanks repair of the system within six months is adequate to minimize general corrosion.
Date: April 12, 1995
Creator: Wiersma, B.J. & Sindelar, R. L.
Partner: UNT Libraries Government Documents Department

Corrosion testing of Type 304L stainless steel for waste tank applications

Description: AISI Type 304L stainless steel will be the material of construction for hazardous waste storage tanks. The corrosion behavior of 304L was characterized in simulated waste solutions using potentiodynamic polarization, electrochemical impedance spectroscopy and long term immersion tests. The results were correlated to assess the use of corrosion characteristics determined by electrochemical techniques for predicting long term corrosion behavior. The corrosion behaviors of Type A537 carbon steel and Incoloy 825 were also evaluated. A good correlation was found between the results from the electrochemical techniques and the immersion tests.
Date: January 1, 1991
Creator: Wiersma, B.J. & Mickalonis, J.I.
Partner: UNT Libraries Government Documents Department

Constant extension rate testing of Type 304L stainless steel in simulated waste tank environments

Description: New tanks for storage of low level radioactive wastes will be constructed at the Savannah River Site (SRS) of AISI Type 304L stainless steel (304L). The presence of chlorides and fluorides in the wastes may induce Stress Corrosion Cracking (SCC) in 304L. Constant Extension Rate Tests (CERT) were performed to determine the susceptibility of 304L to SCC in simulated wastes. In five of the six tests conducted thus far 304L was not susceptible to SCC in the simulated waste environments. Conflicting results were obtained in the final test and will be resolved by further tests. For comparison purposes the CERT tests were also performed with A537 carbon steel, a material similar to that utilized for the existing nuclear waste storage tanks at SRS.
Date: November 1, 1992
Creator: Wiersma, B. J.
Partner: UNT Libraries Government Documents Department

Tank 12H Acidic Chemical Cleaning Sample Analysis And Material Balance

Description: A process of Bulk Oxalic Acid (BOA) chemical cleaning was performed for Tank 12H during June and July of 2013 to remove all or a portion of the approximately 4400 gallon sludge heel. Three strikes of oxalic acid (nominally 4 wt % or 2 wt %) were used at 55 �C and tank volumes of 96- to 140-thousand gallons. This report details the sample analysis of a scrape sample taken prior to BOA cleaning and dip samples taken during BOA cleaning. It also documents a rudimentary material balance for the Tank 12H cleaning results.
Date: November 8, 2013
Creator: Martino, C. J.; Reboul, S. H.; Wiersma, B. J. & Coleman, C. J.
Partner: UNT Libraries Government Documents Department

A visual assessment of the concrete vaults which surround underground waste storage tanks

Description: Radioactive waste produced at the Savannah River Site (SRS) is stored in underground tanks. There are four different waste tank designs. For each waste tank design the outermost containment shield between the waste and the soil is a concrete vault surrounding the carbon steel liner(s). Should the primary and/or secondary liner be breached, the concrete vault would slow transport of the waste so that contamination of the soil is minimized. The type 3 waste tanks have a stated design life of 40--60 years. With the uncertainty of the schedule for transfer of the waste to the Defense Waste Processing Facility, it is conceivable that the tanks will be required to function past their design life. The Department of Energy formed a Waste Tank Structural Integrity Panel to investigate the potential for aging and degradation of underground radioactive waste storage tanks employed in the weapons complex. The panel is focusing on how each site in the complex: (1) inspects the waste tanks for degradation, (2) understands the potential degradation mechanisms which may occur at their sites, and (3) mitigates the known potential degradation mechanisms. In addition to the carbon steel liners, the degradation of the concrete vault has also been addressed by the panel. High Level Waste Engineering (HLWE) at SRS has formed a task team to identify key issues that determine and/or effect the condition of the concrete. In June 1993, slides were reviewed which showed the inside of the concrete vault in Type 1, 2, and 4 tanks. The authors subsequently visited the tank farm and assessed the visible portions of the outer concrete vault. Later a team of engineers knowledgeable in concrete degradation performed a walk-down. Photographs showing the concrete condition were taken at this time. This report summarizes the findings of these walk-downs and reinforces previous recommendations.
Date: December 1, 1993
Creator: Wiersma, B. J. & Shurrab, M. S.
Partner: UNT Libraries Government Documents Department

Practical guidelines for small-volume additions of uninhibited water to waste storage tanks

Description: Allowable volumes of uninhibited water additions to waste tanks are limited to volumes in which hydroxide and nitrite inhibitors reach required concentrations by diffusion from the bulk waste within five days. This diffusion process was modeled conservatively by Fick`s second law of diffusion. The solution to the model was applied to all applicable conditions which exist in the waste tanks. Plant engineers adapted and incorporated the results into a practical working procedure for controlling and monitoring the addition of uninhibited water. Research, technical support, and field engineers worked together to produce an effective solution to a potential waste tank corrosion problem.
Date: December 1, 1994
Creator: Hsu, T. C.; Wiersma, B. J.; Zapp, P. E. & Pike, J. A.
Partner: UNT Libraries Government Documents Department