Radiological Instrumentation Assessment for King County Wastewater Treatment Division (open access)

Radiological Instrumentation Assessment for King County Wastewater Treatment Division

The King County Wastewater Treatment Division (WTD) have concern about the aftermath of a radiological dispersion event (RDE) leading to the introduction of significant quantities of radioactive material into its combined sanitary and storm sewer system. Radioactive material could come from the use of a radiological dispersion device (RDD). RDDs include "dirty bombs" that are not nuclear detonations but are explosives designed to spread radioactive material. Radioactive material also could come from deliberate introduction or dispersion of radioactive material into the environment, including waterways and water supply systems. Volume 2 of PNNL-15163 assesses the radiological instrumentation needs for detection of radiological or nuclear terrorism, in support of decisions to treat contaminated wastewater or to bypass the West Point Treatment Plant (WPTP), and in support of radiation protection of the workforce, the public, and the infrastructure of the WPTP. Fixed radiation detection instrumentation should be deployed in a defense-in-depth system that provides 1) early warning of significant radioactive material on the way to the WPTP, including identification of the radionuclide(s) and estimates of the soluble concentrations, with a floating detector located in the wet well at the Interbay Pump Station and telemetered via the internet to all authorized locations; 2) monitoring …
Date: May 19, 2005
Creator: Strom, Daniel J.; McConn, Ronald J. & Brodzinski, Ronald L.
Object Type: Report
System: The UNT Digital Library
New cubic phase of lithium nitride to 200 GPa (open access)

New cubic phase of lithium nitride to 200 GPa

We present a new cubic ({gamma}) Li{sub 3}N phase discovered above 40({+-}5) GPa. Structure and electronic bands are examined at high pressure with synchrotron x-ray diffraction and inelastic x-ray scattering in a diamond anvil cell, and also with first-principles calculations. We observe a dramatic band-gap widening and volume collapse at the phase transition. {gamma}-Li{sub 3}N remains extremely stable and ionic to 200 GPa, with predicted metallization near 8 TPa. The high structural stability, wide band-gap and simple electronic structure of {gamma}-Li{sub 3}N are analogous to that of such lower valence closed-shell solids as NaCl, MgO and Ne, meriting its use as a low-Z internal pressure standard.
Date: July 19, 2005
Creator: Lazicki, A.; Maddox, B.; Evans, W.; Yoo, C. S.; McMahan, A. K.; Pickett, W. E. et al.
Object Type: Article
System: The UNT Digital Library
Calibration of Small Plastic Scintillators for Imaging Applications (open access)

Calibration of Small Plastic Scintillators for Imaging Applications

This report presents the results of measurements and simulations performed with 12 small plastic scintillation detectors manufactured by Scionix for imaging applications. The scintillator is equivalent to a Bicron BC-420 plastic scintillator. A gamma calibration is presented to determine the voltage to be applied on each detector to ensure uniform detector operation. Time of flight measurements performed with a Cf-252 source are also presented. Comparisons between experimental data and data from the Monte Carlo simulations show good agreement for time lags of 0 to 70 ns.
Date: January 19, 2005
Creator: Pozzi, S.
Object Type: Report
System: The UNT Digital Library
TRANSPARENCY: Tracking Uranium under the U.S. / Russian HEU Purchase Agreement (open access)

TRANSPARENCY: Tracking Uranium under the U.S. / Russian HEU Purchase Agreement

By the end of August, 2005, the Russia Federation delivered to the United States (U.S.) more than 7,000 metric tons (MT) of low enriched uranium (LEU) containing approximately 46 million SWU and 75,000 MT of natural uranium. This uranium was blended down from weapons-grade (nominally enriched to 90% {sup 235}U) highly enriched uranium (HEU) under the 1993 HEU Purchase Agreement that provides for the blend down of 500 MT HEU into LEU for use as fuel in commercial nuclear reactors. The HEU Transparency Program, under the National Nuclear Security Administration (NNSA), monitored the conversion and blending of the more than 250 MT HEU used to produce this LEU. The HEU represents more than half of the 500 MT HEU scheduled to be blended down through the year 2013 and is equivalent to the elimination of more than 10,000 nuclear devices. The HEU Transparency Program has made considerable progress in its mission to develop and implement transparency measures necessary to assure that Russian HEU extracted from dismantled Russian nuclear weapons is blended down into LEU for delivery to the United States. U.S. monitor observations include the inventory of in process containers, observation of plant operations, nondestructive assay measurements to determine {sup …
Date: October 19, 2005
Creator: Benton, J B; Decman, D J & Leich, D A
Object Type: Article
System: The UNT Digital Library
Predictive Assay For Cancer Targets (open access)

Predictive Assay For Cancer Targets

Early detection of cancer is a key element in successful treatment of the disease. Understanding the particular type of cancer involved, its origins and probable course, is also important. PhIP (2-amino-1-methyl-6 phenylimidazo [4,5-b]pyridine), a heterocyclic amine produced during the cooking of meat at elevated temperatures, has been shown to induce mammary cancer in female, Sprague-Dawley rats. Tumors induced by PhIP have been shown to contain discreet cytogenetic signature patterns of gains and losses using comparative genomic hybridization (CGH). To determine if a protein signature exists for these tumors, we are analyzing expression levels of the protein products of the above-mentioned tumors in combination with a new bulk protein subtractive assay. This assay produces a panel of antibodies against proteins that are either on or off in the tumor. Hybridization of the antibody panel onto a 2-D gel of tumor or control protein will allow for identification of a distinct protein signature in the tumor. Analysis of several gene databases has identified a number of rat homologs of human cancer genes located in these regions of gain and loss. These genes include the oncogenes c-MYK, ERBB2/NEU, THRA and tumor suppressor genes EGR1 and HDAC3. The listed genes have been shown to …
Date: September 19, 2005
Creator: Suess, A.; Nguyen, C.; Sorensen, K.; Montgomery, J.; Souza, B.; Kulp, K. et al.
Object Type: Article
System: The UNT Digital Library
Sphere-Pac Evaluation for Transmutation (open access)

Sphere-Pac Evaluation for Transmutation

The U.S. Department of Energy Advanced Fuel Cycle Initiative (AFCI) is sponsoring a project at Oak Ridge National Laboratory with the objective of conducting the research and development necessary to evaluate the use of sphere-pac transmutation fuel. Sphere-pac fuels were studied extensively in the 1960s and 1970s. More recently, this fuel form is being studied internationally as a potential plutonium-burning fuel. For transmutation fuel, sphere-pac fuels have potential advantages over traditional pellet-type fuels. This report provides a review of development efforts related to the preparation of sphere-pac fuels and their irradiation tests. Based on the results of these tests, comparisons with pellet-type fuels are summarized, the advantages and disadvantages of using sphere-pac fuels are highlighted, and sphere-pac options for the AFCI are recommended. The Oak Ridge National Laboratory development activities are also outlined.
Date: May 19, 2005
Creator: Icenhour, A.S.
Object Type: Report
System: The UNT Digital Library
Transport of Radioactive Material by Alpha Recoil (open access)

Transport of Radioactive Material by Alpha Recoil

The movement of high-specific-activity radioactive particles (i.e., alpha recoil) has been observed and studied since the early 1900s. These studies have been motivated by concerns about containment of radioactivity and the protection of human health. Additionally, studies have investigated the potential advantage of alpha recoil to effect separations of various isotopes. This report provides a review of the observations and results of a number of the studies.
Date: May 19, 2005
Creator: Icenhour, A.S.
Object Type: Report
System: The UNT Digital Library
RADIONUCLIDE TRANSPORT IN FRACTURED TUFF UNDER EPISODIC FLOW CONDITIONS (open access)

RADIONUCLIDE TRANSPORT IN FRACTURED TUFF UNDER EPISODIC FLOW CONDITIONS

The current conceptual model of radionuclide transport in unsaturated fractured rock includes water movement in fractures, with migration of the entrained radionuclides being retarded by diffusion into and sorption within the rock matrix. Water infiltration and radionuclide transport through low-permeability unsaturated fractured rock are episodic and intermittent in nature, at least at local scales. Under episodic flow conditions, the matrix is constantly imbibing or draining, and this fluctuating wetness both drives two-way advective movement of radionuclides, and forces changes in the matrix diffusivity. This work is intended to examine, both experimentally and numerically, how radionuclide transport under episodic flow conditions is affected by the interacting processes of imbibition and drainage, diffusion, and matrix sorption. Using Topopah Spring welded volcanic tuff, collected from the potential repository geologic unit at Yucca Mountain for storing high-level nuclear waste, we prepared a saw-cut fracture core (length 10.2 cm, diameter 4.4 cm, and fracture aperture 100 {micro}m). The dry core was packed into a flow reactor, flushed with CO{sub 2}, then saturated via slow pumping (0.01 mL/min) of synthetic groundwater. The fractured core was then flushed with air at >97% relative humidity (to simulate in situ unsaturated fractured rock conditions at Yucca Mountain), then the …
Date: September 19, 2005
Creator: Hu, O.; Sun, Y. & Ewing, R.P.
Object Type: Report
System: The UNT Digital Library
Accelerator mass spectrometry for quantitative in vivo tracing (open access)

Accelerator mass spectrometry for quantitative in vivo tracing

Accelerator mass spectrometry (AMS) counts individual rare, usually radio-, isotopes such as radiocarbon at high efficiency and specificity in milligram-sized samples. AMS traces very low chemical doses ({micro}g) and radiative doses (100 Bq) of isotope labeled compounds in animal models and directly in humans for pharmaceutical, nutritional, or toxicological research. Absorption, metabolism, distribution, binding, and elimination are all quantifiable with high precision after appropriate sample definition.
Date: April 19, 2005
Creator: Vogel, J S
Object Type: Article
System: The UNT Digital Library
CONSIDERATIONS OF THE ROLE OF THE CATHODIC REGION IN LOCALIZED CORROSION (open access)

CONSIDERATIONS OF THE ROLE OF THE CATHODIC REGION IN LOCALIZED CORROSION

None
Date: December 19, 2005
Creator: KELLY, R.G., LANDAU, U., PAYER, J.H.
Object Type: Article
System: The UNT Digital Library
General Corrosion and Passive Film Stability (open access)

General Corrosion and Passive Film Stability

This report summarizes both general corrosion of Alloy 22 from 60 to 220 C and the stability of the passive (oxide) film from 60 to 90 C over a range of solution compositions that are relevant to the in-drift chemical environment at the waste package surface. The general corrosion rates were determined by weight-loss measurements in a range of complex solution compositions representing the products of both the evaporation of seepage water and also the deliquescence of dust previously deposited on the waste canisters. These data represent the first weight-loss measurements performed by the program at temperatures above 90 C. The low corrosion rates of Alloy 22 are attributed to the protective oxide film that forms at the metal surface. In this report, changes in the oxide film composition are correlated with weight loss at the higher temperatures (140-220 C) where film characterization had not been previously performed. The stability of the oxide film was further analyzed by conducting a series of electrochemical tests in progressively more acidic solutions to measure the general corrosion rates in solutions that mimic crevice or pit environments.
Date: July 19, 2005
Creator: Orme, C; Gray, J; Hayes, J; Wong, L; Rebak, R; Carroll, S et al.
Object Type: Report
System: The UNT Digital Library
Infrared Lorentz Violation and Slowly InstantaneousElectricity (open access)

Infrared Lorentz Violation and Slowly InstantaneousElectricity

None
Date: January 19, 2005
Creator: Dvali, Gia; Papucci, Michele & Schwartz, Matthew D.
Object Type: Article
System: The UNT Digital Library
Hanford Site Environmental Surveillance Master Sampling Schedule for Calendar Year 2005 (open access)

Hanford Site Environmental Surveillance Master Sampling Schedule for Calendar Year 2005

Environmental surveillance of the Hanford Site and surrounding areas is conducted by the Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE). Sampling is conducted to evaluate levels of radioactive and nonradioactive pollutants in the Hanford environs. This document contains the calendar year 2005 schedules for the routine and non-routine collection of samples for the Surface Environmental Surveillance Project (SESP) and Drinking Water Monitoring Project.
Date: January 19, 2005
Creator: Bisping, Lynn E.
Object Type: Report
System: The UNT Digital Library
Miniatuization of the flowing fluid electric conductivity loggingtec hnique (open access)

Miniatuization of the flowing fluid electric conductivity loggingtec hnique

An understanding of both the hydraulic properties of the aquifer and the depth distribution of salts is critical for evaluating the potential of groundwater for conjunctive water use and for maintaining suitable groundwater quality in agricultural regions where groundwater is used extensively for irrigation and drinking water. The electrical conductivity profiles recorded in a well using the flowing fluid electric conductivity logging (FEC logging) method can be analyzed to estimate interval specific hydraulic conductivity and estimates of the salinity concentration with depth. However, irrigation wells that are common in agricultural regions have limited access into them because these wells are still in operation, and the traditional equipment used for FEC logging cannot fit through the small access pipe intersecting the well. A modified, miniaturized FEC logging technique was developed such that this logging method could be used in wells with limited access. In addition, a new method for injecting water over the entire screened interval of the well was developed to reduce the time required to perform FEC logging. Results of FEC logging using the new methodology and miniaturized system in two irrigation wells are also summarized.
Date: October 19, 2005
Creator: Su, Grace W.; Quinn, Nigel W.T.; Cook, Paul J. & Shipp, William
Object Type: Article
System: The UNT Digital Library
Evaluating Potential for Large Releases from CO2 StorageReservoirs: Analogs, Scenarios, and Modeling Needs (open access)

Evaluating Potential for Large Releases from CO2 StorageReservoirs: Analogs, Scenarios, and Modeling Needs

While the purpose of geologic storage of CO{sub 2} in deep saline formations is to trap greenhouse gases underground, the potential exists for CO{sub 2} to escape from the target reservoir, migrate upward along permeable pathways, and discharge at the land surface. Such discharge is not necessarily a serious concern, as CO{sub 2} is a naturally abundant and relatively benign gas in low concentrations. However, there is a potential risk to health, safety and environment (HSE) in the event that large localized fluxes of CO{sub 2} were to occur at the land surface, especially where CO{sub 2} could accumulate. In this paper, we develop possible scenarios for large CO{sub 2} fluxes based on the analysis of natural analogues, where large releases of gas have been observed. We are particularly interested in scenarios which could generate sudden, possibly self-enhancing, or even eruptive release events. The probability for such events may be low, but the circumstances under which they might occur and potential consequences need to be evaluated in order to design appropriate site selection and risk management strategies. Numerical modeling of hypothetical test cases is needed to determine critical conditions for such events, to evaluate whether such conditions may be possible …
Date: September 19, 2005
Creator: Birkholzer, Jens; Pruess, Karsten; Lewicki, Jennifer; Tsang,Chin-Fu & Karimjee, Anhar
Object Type: Article
System: The UNT Digital Library
Radiation Research Symposium: Chemistry and Biology of Radical-mediated Deoxyribose Oxidation in DNA (open access)

Radiation Research Symposium: Chemistry and Biology of Radical-mediated Deoxyribose Oxidation in DNA

The $3000 of funding provided by this grant supported a well-attended (150 people) symposium at the annual Radiation Research Society meeting in Denver, Colorado, on October 19, 2005. The symposium was entitled, ''Chemistry and Biology of Radical-mediated Deoxyribose Oxidation in DNA'', and it focused on the chemistry of damage to deoxyribose caused by radiation and other oxidants, and the role of this chemistry in the biological consequences and responses of cells to chemical and physical insults. The talks highlighted the emerging evidence for a major role for deoxyribose oxidation in the toxic effects of ionizing radiation.
Date: October 19, 2005
Creator: Dedon, Peter
Object Type: Report
System: The UNT Digital Library
Density Changes in Plutonium Observed from Accelerated Aging Using Pu-238 Enrichment (open access)

Density Changes in Plutonium Observed from Accelerated Aging Using Pu-238 Enrichment

In support of Stockpile Stewardship activities, accelerated aging tests on a plutonium alloy enriched with 7.3 atomic percentage of {sup 238}Pu is underway using dilatometry at 35, 50, and 65 C and immersion density measurements of material stored at 50 C. Changes in density are expected from radiation damage in the lattice and helium in-growth. After twenty-five equivalent years of aging, the dilatometry data shows that the alloys at 35 C have expanded in volume by 0.11% to 0.12% and have started to exhibit a near linear expansion behavior primarily caused by the helium accumulation. The average He-to-vacancy ratio from tested specimens was determined to be around 2.3. The model for the lattice damage and helium in-growth accurately represents the volume swelling at 35 C. The density converted from the dilatometry corresponds well to the decreasing density trend of reference plutonium alloys as a function of time.
Date: October 19, 2005
Creator: Chung, B. W.; Thompson, S. R.; Woods, C. H.; Hopkins, D. J.; Gourdin, W. H. & Ebbinghaus, B. B.
Object Type: Article
System: The UNT Digital Library
X-Ray Emission Cross Sections following Charge Exchange by Multiply-Charged Ions of Astrophysical Interest (open access)

X-Ray Emission Cross Sections following Charge Exchange by Multiply-Charged Ions of Astrophysical Interest

State selective nl-electron capture cross sections are presented for highly charged ions with Z = 6-10 colliding with atoms and molecules. The energy range investigated was from 1 eV/amu (v = 0.006 a.u.) to 100 keV/amu (v =2.0 a.u.). The energy dependence of the l-level populations is investigated. The K-shell x-ray emission cross sections are determined by using the calculated state-selective electron capture results as input and then applying hydrogenic branching and cascading values for the photon emission. A major shift in the line emission from being almost solely Lyman-{alpha} transitions at the highest collisions energies to strong high-n to 1s transitions at the lowest energies is observed. The calculated cross sections are in reasonable accord with measurements made by Greenwood et al, Phys. Rev. A 63, 062707 (2001), using O{sup 8+} and Ne{sup 10+} on various targets at 3 keV/amu. The calculations are also in accord with x-ray emission cross section data obtained on the EBIT machine at LLNL where O{sup 8+} and Ne{sup 10+} high resolution measurements were made at a temperature of 10 eV/amu for a series of targets with varying ionization potentials. The Ne{sup 10+} data clearly shows the contribution from multiple capture followed by Auger …
Date: September 19, 2005
Creator: Otranto, S; Olson, R E & Beiersdorfer, P
Object Type: Article
System: The UNT Digital Library
Estimation of Leak Rate from the Emergency Pump Well in L-Area Complex Basin (open access)

Estimation of Leak Rate from the Emergency Pump Well in L-Area Complex Basin

This report provides an estimate of the leak rate from the emergency pump well in L-basin that is to be expected during an off-normal event. This estimate is based on expected shrinkage of the engineered grout (i.e., controlled low strength material) used to fill the emergency pump well and the header pipes that provide the dominant leak path from the basin to the lower levels of the L-Area Complex. The estimate will be used to provide input into the operating safety basis to ensure that the water level in the basin will remain above a certain minimum level. The minimum basin water level is specified to ensure adequate shielding for personnel and maintain the ''as low as reasonably achievable'' concept of radiological exposure. The need for the leak rate estimation is the existence of a gap between the fill material and the header pipes, which penetrate the basin wall and would be the primary leak path in the event of a breach in those pipes. The gap between the pipe and fill material was estimated based on a full scale demonstration pour that was performed and examined. Leak tests were performed on full scale pipes as a part of this …
Date: December 19, 2005
Creator: Duncan, A
Object Type: Report
System: The UNT Digital Library
Environmentally Assisted Cracking in Light Water Reactors : Annual Report, January-December 2003. (open access)

Environmentally Assisted Cracking in Light Water Reactors : Annual Report, January-December 2003.

None
Date: August 19, 2005
Creator: Alexandreanu, B.; Chopra, O. K.; Chung, H. M.; Gruber, E. E. & Shack, W.J.
Object Type: Report
System: The UNT Digital Library
Geomechanical/Geochemical Modeling Studies Conducted within theInternational DECOVALEX Project (open access)

Geomechanical/Geochemical Modeling Studies Conducted within theInternational DECOVALEX Project

The DECOVALEX project is an international cooperative project initiated by SKI, the Swedish Nuclear Power Inspectorate, with participation of about 10 international organizations. The general goal of this project is to encourage multidisciplinary interactive and cooperative research on modeling coupled thermo-hydro-mechanical-chemical (THMC) processes in geologic formations in support of the performance assessment for underground storage of radioactive waste. One of the research tasks, initiated in 2004 by the U.S. Department of Energy (DOE), addresses the long-term impact of geomechanical and geochemical processes on the flow conditions near waste emplacement tunnels. Within this task, four international research teams conduct predictive analysis of the coupled processes in two generic repositories, using multiple approaches and different computer codes. Below, we give an overview of the research task and report its current status.
Date: October 19, 2005
Creator: Birkholzer, J.T.; Rutqvist, J.; Sonnenthal, E.L.; Barr, D.; Chijimatsu, M.; Kolditz, O. et al.
Object Type: Article
System: The UNT Digital Library
Reduced-Temperature Transient-Liquid-Phase Bonding of AluminaUsing a Ag-Cu-Based Brazing Alloy (open access)

Reduced-Temperature Transient-Liquid-Phase Bonding of AluminaUsing a Ag-Cu-Based Brazing Alloy

The mechanical properties and microstructural evolution ofmetal-ceramic bonds produced using a transient liquid phase (TLP) aredescribed. Alumina (Al2O3) was joined at 500 degrees C, 600 degrees C,and 700 degrees C using a multilayer In/Cusil-ABA (R) (commercialcopper-silver eutectic brazing alloy)/In interlayer. The introduction ofthin In cladding layers allows the system to bond at much lowertemperatures than those typically used for brazing with Cusil-ABA (R),thereby protecting temperature-sensitive components. After chemicalhomogenization, the interlayers retain an operating temperature rangesimilar to that of the brazed joints. TLP bonds made at 500 degrees C,600 degrees C, and 700 degrees C with holding times ranging from as lowas 1.5 h to 24 h had average fracture strengths above 220 MPa. Theeffects of bonding temperature and time on fracture strength aredescribed. Preliminary analysis of the interlayers shows that the Ag-Inor Cu-In intermetallic phases do not form. Considerations unique tosystems with two-phase core layers are discussed. Experiments usingsingle-crystal sapphire indicate rapid formation of a reaction layer at700 degrees C, suggesting the possibility of making strong bonds usinglower temperatures and/or shorter processing times.
Date: December 19, 2005
Creator: Hong, Sung Moo & Glaeser, Andreas M.
Object Type: Article
System: The UNT Digital Library
Gyrokinetic Stability Studies of the Microtearing Mode in the National Spherical Torus Experiment H-mode (open access)

Gyrokinetic Stability Studies of the Microtearing Mode in the National Spherical Torus Experiment H-mode

Insight into plasma microturbulence and transport is being sought using linear simulations of drift waves on the National Spherical Torus Experiment (NSTX), following a study of drift wave modes on the Alcator C-Mod Tokamak. Microturbulence is likely generated by instabilities of drift waves, which cause transport of heat and particles. Understanding this transport is important because the containment of heat and particles is required for the achievement of practical nuclear fusion. Microtearing modes may cause high heat transport through high electron thermal conductivity. It is hoped that microtearing will be stable along with good electron transport in the proposed low collisionality International Thermonuclear Experimental Reactor (ITER). Stability of the microtearing mode is investigated for conditions at mid-radius in a high density NSTX high performance (H-mode) plasma, which is compared to the proposed ITER plasmas. The microtearing mode is driven by the electron temperature gradient, and believed to be mediated by ion collisions and magnetic shear. Calculations are based on input files produced by TRXPL following TRANSP (a time-dependent transport analysis code) analysis. The variability of unstable mode growth rates is examined as a function of ion and electron collisionalities using the parallel gyrokinetic computational code GS2. Results show the microtearing …
Date: October 19, 2005
Creator: Baumgaertel J.A., Redi M.H., Budny R.V., Rewoldt G., Dorland W.
Object Type: Report
System: The UNT Digital Library
Clean Assembly Practices to Prevent Contamination and Damage to Optics (open access)

Clean Assembly Practices to Prevent Contamination and Damage to Optics

A key lesson learned from the earliest optics installed in the National Ignition Facility (NIF) was that the traditional approach for maintaining cleanliness, such as the use of cleanrooms and associated garments and protocols, is inadequate. Assembly activities often negate the benefits provided by cleanrooms, and in fact generate contamination with high damage potential. As a result, NIF introduced ''clean assembly protocols'' and related practices to supplement the traditional clean room protocols. These new protocols included ''clean-as-you-go'' activities and regular bright light inspections. Introduction of these new protocols has greatly reduced the particle contamination found on more recently installed optics. In this paper we will describe the contamination mechanisms we have observed and the details of the clean assembly protocols we have successfully introduced to mitigate them.
Date: December 19, 2005
Creator: Pryatel, J & Gourdin, W H
Object Type: Article
System: The UNT Digital Library