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Effect of Mo on pitting corrosion of ferritic steels in bromide and chloride solutions

Description: A model for pitting corrosion of stainless steels, independent of changes of passive film properties, was tested using Fe-18%Cr-x%Mo alloys in bromide and chlorine solutions. In 1M LiCl the pitting potential improved from {minus}50 mV{sub sce} to about 1200 mV{sub sce} on increasing Mo from 2% to 10%. In 1M LiBr the pitting potential increased from 125 to only 560 mV{sub sce}. Active dissolution kinetics of these steels in saturated solutions in a simulated pit were measured. Tafel lines for dissolution moved to more noble potentials with increases in Mo, indicating Mo inhibited dissolution rates. The potential increases were found to be equal to the increases in pitting potential for both halides. Agreement was interpreted in terms maintaining high halide concentrations in the pit by high rates of active metal dissolution. Bromide was less effective suggesting it interacted with Mo adsorbed on the dissolving surface.
Date: December 1, 1997
Creator: Kaneko, M. & Isaacs, H.S.
Partner: UNT Libraries Government Documents Department

The Correlation of Coupled Heat and Mass Transfer Experimental Data for Vertical Falling Film Absorption

Description: Absorption chillers are gaining global acceptance as quality comfort cooling systems. These machines are the central chilling plants and the supply for cotnfort cooling for many large commercial buildings. Virtually all absorption chillers use lithium bromide (LiBr) and water as the absorption fluids. Water is the refrigerant. Research has shown LiBr to he one of the best absorption working fluids because it has a high affinity for water, releases water vapor at relatively low temperatures, and has a boiling point much higher than that of water. The heart of the chiller is the absorber, where a process of simultaneous heat and mass transfer occurs as the refrigerant water vapor is absorbed into a falling film of aqueous LiBr. The more water vapor absorbed into the falling film, the larger the chiller�s capacity for supporting comfort cooling. Improving the performance of the absorber leads directly to efficiency gains for the chiller. The design of an absorber is very empirical and requires experimental data. Yet design data and correlations are sparse in the open literature. The experimental data available to date have been derived at LiBr concentrations ranging from 0.30 to 0.60 mass fraction. No literature data are readily available for the design operating conditions of 0.62 and 0.64 mass fraction of LiBr and absorber pressures of 0.7 and 1.0 kPa.
Date: November 14, 1999
Creator: Keyhani, M. & Miller, W.A.
Partner: UNT Libraries Government Documents Department

The Synergism Between Heat and Mass Transfer Additive and Advanced Surfaces in Aqueous LiBr Horizontal Tube Absorbers

Description: Experiments were conducted in a laboratory to investigate the absorption of water vapor into a falling-film of aqueous lithium bromide (LiBr). A mini-absorber test stand was used to test smooth tubes and a variety of advanced tube surfaces placed horizontally in a single-row bundle. The bundle had six copper tubes; each tube had an outside diameter of 15.9-mm and a length of 0.32-m. A unique feature of the stand is its ability to operate continuously and support testing of LiBr brine at mass fractions {ge} 0.62. The test stand can also support testing to study the effect of the failing film mass flow rate, the coolant mass flow rate, the coolant temperature, the absorber pressure and the tube spacing. Manufacturers of absorption chillers add small quantities of a heat and mass transfer additive to improve the performance of the absorbers. The additive causes surface stirring which enhances the transport of absorbate into the bulk of the film. Absorption may also be enhanced with advanced tube surfaces that mechanically induce secondary flows in the falling film without increasing the thickness of the film. Several tube geometry's were identified and tested with the intent of mixing the film and renewing the interface with fresh solution from the tube wall. Testing was completed on a smooth tube and several different externally enhanced tube surfaces. Experiments were conducted over the operating conditions of 6.5 mm Hg absorber pressure, coolant temperatures ranging from 20 to 35 C and LiBr mass fractions ranging from 0.60 through 0.62. Initially the effect of tube spacing was investigated for the smooth tube surface, tested with no heat and mass transfer additive. Test results showed the absorber load and the mass absorbed increased as the tube spacing increased because of the improved wetting of the tube bundle. However, tube spacing ...
Date: March 24, 1999
Creator: Miller, W.A.
Partner: UNT Libraries Government Documents Department

Blending Study of MgO-Based Separator Materials for Thermal Batteries

Description: The development and testing of a new technique for blending of electrolyte-binder (separator) mixes for use in thermal batteries is described. The original method of blending such materials at Sandia involved liquid Freon TF' as a medium. The ban on the use of halogenated solvents throughout much of the Department of Energy complex required the development of an alternative liquid medium as a replacement. The use of liquid nitrogen (LN) was explored and developed into a viable quality process. For comparison, a limited number of dry-blending tests were also conducted using a Turbula mixer. The characterization of pellets made from LN-blended separators involved deformation properties at 530 C and electrolyte-leakage behavior at 400 or 500 C, as well as performance in single-cells and five-cell batteries under several loads. Stack-relaxation tests were also conducted using 10-cell batteries. One objective of this work was to observe if correlations could be obtained between the mechanical properties of the separators and the performance in single cells and batteries. Separators made using three different electrolytes were examined in this study. These included the LiCl-KCl eutectic, the all-Li LiCl-LiBr-LiF electrolyte, and the low-melting LiBr-KBr-LiF eutectic. The electrochemical performance of separator pellets made with LN-blended materials was compared to that for those made with Freon T P and, in some cases, those that were dry blended. A satisfactory replacement MgO (Marinco 'OL', now manufactured by Morton) was qualified as a replacement for the standard Maglite 'S' MgO that has been used for years but is no longer commercially available. The separator compositions with the new MgO were optimized and included in the blending and electrochemical characterization tests.
Date: June 1, 2002
Creator: GUIDOTTI, RONALD A.; REINHARDT, FREDERICK W. & ANDAZOLA, ARTHUR H.
Partner: UNT Libraries Government Documents Department

A study of the behavior of bromide in artificial pits using in situ X-ray microprobe analysis

Description: An in situ X-ray microprobe analysis of Type 316 stainless steel artificial pits has been carried out with a bromide/chloride solution. A high intensity 8 micron diameter polychromatic X-ray beam was scanned across the steel solution interface within the artificial pit. The resulting X-ray fluorescence was analyzed using an energy dispersive X-ray detector. In contrast to the light Cl atom, Br could be detected, making it possible to monitor the behavior of halides in the artificial pits and in the salt layer at the interface. It was found that Br was more active than Cl. At high potentials, elemental Br was produced as an oxidation product, whereas without added bromide, chloride only formed a salt layer. Br also concentrated at the salt steel interface at potentials below where it was oxidized.
Date: December 31, 1997
Creator: Isaacs, H.S. & Kaneko, M.
Partner: UNT Libraries Government Documents Department

From fire to ice

Description: Absorption chillers are heat-operate refrigeration without harmful environmental emissions (CFCs, HCFCS, and HFCS). The machine uses either steam or a gas-fired burner as the energy source and utilizes endothermic evaporation to provide refrigeration to an external process fluid, usually chilled water. In the United States, absorption chillers are used in regions where the cost of electricity is high relative to natural gas. Absorption chillers are also used in applications where steam is readily available or in areas where seasonal load peaks cause utilities to subsidize gas cooling. This paper will describe the history of absorption, the basic absorption refrigeration cycle and some advanced high efficiency cycles. Practical applications of absorption refrigeration to commercial end uses will also be discussed.
Date: June 1, 1995
Creator: Adcock, P.W.
Partner: UNT Libraries Government Documents Department

Continued investigations of the occurrence of water in Pahute Mesa emplacement holes

Description: Periodically, water has been observed in emplacement boreholes drilled for underground testing of nuclear weapons at Pahute Mesa, Nevada Test Site, and is often at levels elevated above the predicted local water table. Water which may provide a means to transport residual radionuclides away from weapon tests may originate as fluids introduced during drilling, from naturally perched groundwater draining into the borehole, or from penetration of the local groundwater table. Lithium-bromide (Li-Br) tracer is being used to evaluate both the origin and movement of these borehole waters. The drilling fluid used to drill the final 100 meters of borehole U-19bh was chemically labeled with LiBr tracer. Lack of significant increase in borehole Br inventory over time indicates that standing water in U-9bh is not returned drilling fluid. Possible sources for the standing water are drilling fluid infiltrated above the bottom 100 in or natural water from a perched or shallower-than-expected saturated zone. The minimum detectable Darcy velocity of water passing through U-19bh is 0.3 m/yr. Borehole U-19bk has a water level approximately 50 in above the predicted pre-drilling water level. Initial water samples were collected from U-19bk to characterize the borehole water quality prior to adding the tracer. The major-ion analytical results of U-19bk along with historical water quality analyses of Water Well 20 and water well UE-19c show that all three waters are similar in character and therefore the water in U-19bk may be either residual drilling fluids originating from Water Well 20 and UE-19c or naturally occurring Pahute Mesa groundwater. LiBr tracer was added to the U-19bk borehole and samples for tracer analysis were collected one month later. For the one month period, no detectable loss of Br was observed. Over this short time period, the minimum detectable Darcy velocity is 10.6 m/yr.
Date: April 1, 1995
Creator: Hershey, R.L. & Brikowski, T.H.
Partner: UNT Libraries Government Documents Department

Migration of Water Pulse Through Fractured Porous Media

Description: Contaminant transport from waste-disposal sites is strongly affected by the presence of fractures and the degree of fracture-matrix interaction. Characterization of potential contaminant plumes at such sites is difficult, both experimentally and numerically. Simulations of water flow through fractured rock were performed to examine the penetration depth of a large pulse of water entering such a system. Construction water traced with lithium bromide was released during the excavation of a tunnel at Yucca Mountain, Nevada, which is located in an unsaturated fractured tuff formation. Modeling of construction-water migration is qualitatively compared with bromide-to-chloride (Br/CI) ratio data for pore-water salts extracted from drillcores. The influences of local heterogeneities in the fracture network and variations in hydrogeologic parameters were examined by sensitivity analyses and Monte Carlo simulations. The simulation results are qualitatively consistent with the observed Br/CI signals, although these data may only indicate a minimum penetration depth, and water may have migrated further through the fracture network.
Date: June 6, 2001
Creator: Finsterle, S.; Fabryka-Martin, J. T. & Wang, J. S. Y.
Partner: UNT Libraries Government Documents Department

Hydrologic Data and Evaluation for Model Validation Wells, MV-1, MV-2, and MV-3 near the Project Shoal Area

Description: In 2006, a drilling campaign was conducted at the Project Shoal Area (PSA) to provide information for model validation, emplace long-term monitoring wells, and develop baseline geochemistry for long term hydrologic monitoring. Water levels were monitored in the vicinity of the drilling, in the existing wells HC-1 and HC-6, as well as in the newly drilled wells, MV-1, MV-2 and MV-3 and their associated piezometers. Periodic water level measurements were also made in existing wells HC-2, HC-3, HC-4, HC-5 and HC-7. A lithium bromide chemical tracer was added to drilling fluids during the installation of the monitoring and validation (MV) wells and piezometers. The zones of interest were the fractured, jointed and faulted horizons within a granitic body. These horizons generally have moderate hydraulic conductivities. As a result, the wells and their shallower piezometers required strenuous purging and development to remove introduced drilling fluids as evidenced by bromide concentrations. After airlift and surging well development procedures, the wells were pumped continuously until the bromide concentration was less then 1 milligram per liter (mg/L). Water quality samples were collected after the well development was completed. Tritium scans were preformed before other analyses to ensure the absence of high levels of radioactivity. Tritium levels were less than 2,000 pico-curies per liter. Samples were also analyzed for carbon-14 and iodine-129, stable isotopes of oxygen and hydrogen, as well as major cations and anions. Aquifer tests were performed in each MV well after the bromide concentration fell below acceptable levels. Water level data from the aquifer tests were used to compute aquifer hydraulic conductivity and transmissivity
Date: February 14, 2007
Creator: Lyles, B.; Oberlander, P.; Gillespie, D.; Donithan, D.; Chapman, J. & Healey, J.
Partner: UNT Libraries Government Documents Department

Excess Thermodynamic Properties of Concentrated Aqueous Solutions at High Temperatures

Description: Measurements of the vapor pressure of the solvent in wide ranges of concentration and temperature provide information on solute solvation and ion pairing--the two phenomena most often invoked for description of dilute solutions. Even in moderately concentrated solutions, as interionic distances become comparable to ionic diameters, these simple concepts gradually lose their meaning and solutions behave like molten salts. The usefulness of experimental vapor pressure results increases rapidly with their accuracy, since derived properties, such as solution enthalpies and heat capacities, can be calculated. Very accurate results can be obtained by the isopiestic method, but primary vapor pressure data for standard solutions are needed. In order to obtain vapor pressures at conditions where accurate isopiestic standards are not available and to establish more accurate standards, the ORNL isopiestic apparatus was modified for simultaneous direct vapor pressure measurements and isopiestic comparisons. There are no comprehensive solution theories derived from molecular level models and able to predict thermodynamic properties of various electrolytes as the composition changes from dilute solutions to molten salts in a wide range of temperatures. Empirical and semi-empirical models are useful for representation of experimental results, interpretation of measurements of other properties such as conductance., solubility or liquid-vapor partitioning of solutes, and for verification of theoretical predictions. Vapor pressures for aqueous CaCl{sub 2}, CaBr{sub 2}, LiCl, LiBr, LiI, NaI were measured at temperatures between 380 and 523 K in the concentration range extended to water activities below 0.2 (over 30 mol/kg for LiCl). General equations based on the modified Pitzer ion-interaction model were used to obtain enthalpy and heat capacity surfaces, which are compared with direct calorimetric measurements.
Date: June 7, 2001
Creator: Guszkiewicz, M.S.
Partner: UNT Libraries Government Documents Department

Characterization of low-melting electrolytes for potential geothermal borehole power supplies: The LiBr-KBr-LiF eutectic

Description: The suitability of modified thermal-battery technology for use as a potential power source for geothermal borehole applications is under investigation. As a first step, the discharge processes that take place in LiSi/LiBr-KBr-LiF/FeS{sub 2} thermal cells were studied at temperatures of 350 C and 400 C using pelletized cells with immobilized electrolyte. Incorporation of a reference electrode allowed the relative contribution of each electrode to the overall cell polarization to be determined. The results of single-cell tests are presented, along with preliminary data for cells based on a lower-melting CsBr-LiBr-KBr eutectic salt.
Date: May 1, 1998
Creator: Guidotti, R.A. & Reinhardt, F.W.
Partner: UNT Libraries Government Documents Department

Performance of LiAlloy/Ag(2)CrO(4) Couples in Molten CsBr-LiBr-KBr Eutectic

Description: The performance of Li-alloy/CsBr-LiBr-KBr/Ag{sub 2}CrO{sub 4} systems was studied over a temperature range of 250 C to 300 C, for possible use as a power source for geothermal borehole applications. Single cells were discharged at current densities of 15.8 and 32.6 mA/cm{sup 2} using Li-Si and Li-Al anodes. When tested in 5-cell batteries, the Li-Si/CsBr-LiBr-KBr/Ag{sub 2}CrO{sub 4} system exhibited thermal runaway. Thermal analytical tests showed that the Ag{sub 2}CrO{sub 4} cathode reacted exothermically with the electrolyte on activation. Consequently, this system would not be practical for the envisioned geothermal borehole applications.
Date: October 18, 1999
Creator: GUIDOTTI,RONALD A. & REINHARDT,FREDERICK W.
Partner: UNT Libraries Government Documents Department

Re-evaluation of the eutectic region of the LiBr-KBr-LiF system

Description: The separator pellet in a thermal battery consists of electrolyte immobilized by a binder (typically, MgO powder). The melting point of the electrolyte determines the effective operating window for its use in a thermal battery. The development of a two-hour thermal battery required the use of a molten salt that had a lower melting point and larger liquidus range than the LiCl-KCl eutectic which melts at 352 C. Several candidate eutectic electrolyte systems were evaluated for their suitability for this application. One was the LiCl-LiBr-KBr eutectic used at Argonne National Laboratories for high-temperature rechargeable batteries for electric-vehicle applications. Using a custom-designed high-temperature conductivity cell, the authors were able to readily determine the liquidus region for the various compositions studied around the original eutectic for the LiBr-KBr-LiF system. The actual eutectic composition was found to be 60.0 m/o LiBr-37.5 m/o KBr-2.5 m/o LiF with a melting point of 324 {+-} 0.5 C.
Date: May 1, 1996
Creator: Redey, L. & Guidotti, R.A.
Partner: UNT Libraries Government Documents Department

Modification of LiCl-LiBr-KBr electrolyte for LiAl/FeS{sub 2} batteries

Description: The bipolar LiAl/FeS{sub 2} battery is being developed to achieve the high performance and long cycle life needed for electric vehicle application. The molten-salt (400 to 440 C operation) electrolyte composition for this battery has evolved to support these objectives. An earlier change to LiCl-LiBr-KBr electrolyte is responsible for significantly increased cycle life (up to 1,000 cycles). Recent electrolyte modification has significantly improved cell performance; approximately 50% increased power, with increased high rate capacity utilization. Results are based on power-demanding EV driving profile test at 600 W/kg. The effects of adding small amounts (1--5 mol%) of LiF and LiI to LiCl-LiBr-KBr electrolyte are discussed. By cyclic voltammetry, the modified electrolytes exhibit improved FeS{sub 2} electrochemistry. Electrolyte conductivity is little changed, but high current density (200 mA/cm{sup 2}) performance improved by approximately 50%. A specific feature of the LiI addition is an enhanced cell overcharge tolerance rate from 2.5 to 5 mA/cm{sup 2}. The rate of overcharge tolerance is related to electrolyte properties and negative electrode lithium activity. As a result, the charge balancing of a bipolar battery configuration with molten-salt electrolyte is improved to accept greater cell-to-cell deviations.
Date: June 1, 1996
Creator: Kaun, T.D.; Jansen, A.N.; Henriksen, G.L. & Vissers, D.R.
Partner: UNT Libraries Government Documents Department

Characterization of the LiSi/CsBr-LiBr-KBr/FeS(2) System for Potential Use as a Geothermal Borehole Power Source

Description: We are continuing to study the suitability of modified thermal-battery technology as a potential power source for geothermal borehole applications. Previous work focused on the LiSi/FeS{sub 2} couple over a temperature range of 350 C to 400 C with the LiBr-KBr-LiF eutectic, which melts at 324.5 C. In this work, the discharge processes that take place in LiSi/CsBr-LiBr-KBr eutectic/FeS{sub 2} thermal cells were studied at temperatures between 250 C and 400 C using pelletized cells with immobilized electrolyte. The CsBr-LiBr-KBr eutectic was selected because of its lower melting point (228.5 C). Incorporation of a quasi-reference electrode allowed the determination of the relative contribution of each electrode to the overall cell polarization. The results of single-cell tests and limited battery tests are presented, along with preliminary data for battery stacks tested in a simulated geothermal borehole environment.
Date: October 18, 1999
Creator: GUIDOTTI, RONALD A. & REINHARDT, FREDERICK W.
Partner: UNT Libraries Government Documents Department

Humectants To Augment Current From Metallized Zinc Cathodic Protection Systems on Concrete

Description: Cathodic protection (CP) systems using thermal-sprayed zinc anodes are employed to mitigate the corrosion process in reinforced concrete structures. However, the performance of the anodes is improved by moisture at the anode-concrete interface. Research was conducted to investigate the effect of hydrophilic chemical additives, humectants, on the electrical performance and service life of zinc anodes. Lithium bromide and lithium nitrate were identified as feasible humectants with lithium bromide performing better under galvanic CP and lithium nitrate performing better under impressed current CP. Both humectants improved the electrical operating characteristics of the anode and increased the service life by up to three years.
Date: December 1, 2002
Creator: Holcomb, Gordon R.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Russell, James H.; Bullard, Sophie J.; Collins, W. Keith et al.
Partner: UNT Libraries Government Documents Department

Solar liquid-desiccant air-conditioning system. Final report

Description: A design for a closed, diurnal, intermittent absorption chiller for passive solar air-conditioning using liquid sorbents has been constructed and tested. LiBr-H/sub 2/O will not work with this design because of its low vapor pressure at the temperature available. The approach has possibilities using the 2 LiBr-ZrBr-CH/sub 3/OH or H/sub 2/O-NH/sub 3/ sorbent refrigerant pairs. The use of H/sub 2/O-NH/sub 3/ appears to be the better candidate because of the lower solution viscosity and less cycle weight, through tank volumes and collector requirements are similar. Further study of other refrigerant pairs such as S-Thiocyanate-ammonia is indicated, however, the difficulties encountered in construction and low potential coefficient of performance, and thus large collection area needed, makes commercialization of such a system doubtful in the foreseeable future.
Date: unknown
Partner: UNT Libraries Government Documents Department

Survey of absorption cooling technology in solar applications

Description: A comprehensive survey of the current state of the absorption cooling technology has been conducted. This survey discusses the basic and applied absorption cooling/heating technology, analyses the current state of the art including the discussion of limitations and possible solutions, identifies areas where promising developments are indicated, lists the current products and activities of the absorption industry, and presents the current RD and D efforts of the U.S. government. The main subjects covered in the survey are as follows: Principles of absorption cooling technology (NH/sub 3/-H/sub 2/O cycle and H/sub 2/O-LiBr Cycle), Adaptation of absorption cooling technology for solar cooling applications, Thermal performance of absorption cooling units, Comparison of NH/sub 3/-H/sub 2/O absorption with H/sub 2/O-LiBr absorption, Commercially available solar absorption units, General trends of the absorption cooling industry toward solar application, Absorption cooling system performance in actual installations, Limitations of absorption cooling technology, Solar-powered absorption heat pumps, and U.S. ERDA activities relating to solar absorption cooling. The treatment of the subjects is intended to be basic and comprehensive in order that the general readers may understand the current aspects of absorption technology in solar cooling applications. 36 references.
Date: July 1, 1977
Creator: Auh, P C
Partner: UNT Libraries Government Documents Department

Development and proof-testing of advanced absorption refrigeration cycle concepts

Description: The overall objectives of this project are to evaluate, develop, and proof-test advanced absorption refrigeration cycles that are applicable to residential and commercial heat pumps for space conditioning. The heat pump system is to be direct-fired with natural gas and is to use absorption working fluids whose properties are known. Target coefficients of performance (COPs) are 1.6 at 47{degrees}F and 1.2 at 17{degrees} in the heating mode, and 0.7 at 95{degree}F in the cooling mode, including the effect of flue losses. The project is divided into three phases. Phase I entailed the analytical evaluation of advanced cycles and included the selection of preferred concepts for further development. Phase II involves the development and testing of critical components and of a complete laboratory breadboard version of the selected system. Phase III calls for the development of a prototype unit and is contingent on the successful completion of Phase II. This report covers Phase I work on the project. In Phase 1, 24 advanced absorption cycle/fluid combinations were evaluated, and computer models were developed to predict system performance. COP, theoretical pump power, and internal heat exchange were calculated for each system, and these calculations were used as indicators of operating and installed costs in order to rank the relative promise of each system. The highest ranking systems involve the cycle concept of absorber/generator heat exchange, generator heat exchanger/absorber heat exchange, regeneration, and resorption/desorption, in combination with the NH{sub 3}/H{sub 2}O/LiBr ternary absorption fluid mixture or with the NH{sub 3}/H{sub 2}O binary solution. Based upon these conclusions, the recommendation was made to proceed to Phase II, the laboratory breadboard proof-of- concept.
Date: March 1, 1992
Creator: Modahl, R. J. & Hayes, F. C.
Partner: UNT Libraries Government Documents Department

Chemical processing of liquid lithium fusion reactor blankets

Description: A 50-gallon-capacity lithium loop constructed mostly from 304L stainless steel has been operated for over 6000 hours at temperatures in the range from 360 to 480/sup 0/C. This facility, the Lithium Processing Test Loop (LPTL), is being used to develop processing and monitoring technology for liquid lithium fusion reactor blankets. Results of tests of a molten-salt extraction method for removing impurities from liquid lithium have yielded remarkably good distribution coefficients for several of the more common nonmetallic elements found in lithium systems. In particular, the equilibrium volumetric distribution coefficients, D/sub v/ (concentration per unit volume of impurity in salt/concentration per unit volume of impurity in lithium), for hydrogen, deuterium, nitrogen and carbon are approx. 3, approx. 4, > 10, approx. 2, respectively. Other studies conducted with a smaller loop system, the Lithium Mini-Test Loop (LMTL), have shown that zirconium getter-trapping can be effectively used to remove selected impurities from flowing lithium.
Date: January 1, 1979
Creator: Weston, J.R.; Calaway, W.F.; Yonco, R.M.; Hines, J.B. & Maroni, V.A.
Partner: UNT Libraries Government Documents Department