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Ceramic BeO exoelectron dosimeters for tritium and radon monitoring

Description: An environmental monitoring device with BeO ceramic dosimeters can be used to measure /sup 222/Rn in dwellings. Radon diffuses into a porous hemispheric chamber and the radon daughters are electrostatically collected on aluminized Mylar foil covering the BeO dosimeter that records the alpha activity. A 10:1 signal-to-background ratio results from a radon exposure of only pCi-h/l. This high sensitivity makes accurate radon measurement possible within one day, even at near background levels of a few tenths pCi/l. The BeO exoelectron dosimeter is also uniquely suited for monitoring occupational exposure to insoluble tritium gas. At one-fifth the maximum permissible concentration, exposure for 8 hours gives a 10:1 signal-to-background exoelectron response to the low energy beta rays. Compensation for any exoelectron response caused by photon radiation can be made by reading the thermoluminescence. The tritium exposure produces negligible thermoluminescence. Progress in these and other applications is now totally dependent on achieving reliability and long-term stability of the exoelectron dosimeter.
Date: January 1, 1979
Creator: Gammage, R.B.
Partner: UNT Libraries Government Documents Department

Optimization of electrochemical-etching parameters for highly sensitive CR-39 fast neutron dosimeters

Description: Voltage gradient and frequency were studied for their influence on the electrochemical etching of CR-39 plastic irradiated with fission spectrum, fast neutrons. A power supply having outputs of up to 1.5 kV (rms) and 5 kHz was used. Differential leakage current measurements under non-etching conditions indicated that the optimal values in electrochemical etching would be 20 kV/cm and 1.3 kHz. That these parameters produced a maximum sensitivity was verified in subsequent electrochemical etching experiments with foils that were both unirradiated and irradiated. The introduction of a proton irradiator cover and a conventional etching step prior to the electrochemical etching, increased the sensitivity to neutrons (approx. 30-fold) and decreased the background track density to 4.4 +- 0.6 tracks/cm/sup 2/. The corresponding sensitivity was then 1.3 tracks/cm/sup 2//mrem with a minimum level of detectability (3sigma) of 1.4 mrem.
Date: January 1, 1981
Creator: Gammage, R.B. & Chowdhury, A.
Partner: UNT Libraries Government Documents Department

Experiences in environmental monitoring with BeO ceramic dosimeters

Description: Ceramic BeO disks used as radiation detectors have been evaluated in environmental radiation fields by observing the TL and TSEE signals given off after heating the disks. Fluxes of low energy photons cause the values for the two apparent exposure rates to diverge; this provides a measure of the quality of the photon radiation field. The mean of the TL and TSEE derived exposure rates is close to the exposure rate as determined by other means. The TL-TSEE dosimeters perform satisfactorily provided moisture is not allowed to condense onto the BeO and wet its surface when the temperature falls below the dew point. Thin impervious plastic packets or aluminium cans, containing silica gel desiccant, provide adequate protection. (auth)
Date: January 1, 1975
Creator: Gammage, R.B. & Haywood, F.F.
Partner: UNT Libraries Government Documents Department

Evaluation of different polymers for fast neutron personnel dosimetry using electrochemical etching

Description: There is considerable optimism for the enhancement by electrochemical etching of fast neutron-induced recoil tracks in polycarbonate for the purpose of personnel dosimetry. The threshold energy, however, is rather high. A desirable improvement would be to lower this energy below 1 MeV. With this objective in mind, we have commenced an investigation of cellulose acetate, triacetate, and acetobutyrate in addition to polycarbonate. These cellulose derivatives are chemically more reactive and physically weaker than polycarbonate. It might, therefore, be possible to initiate the electrochemical amplification at the sites of shorter recoil atom damage tracks than is possible with polycarbonate. Some characteristics important for electrochemically etching in aqueous electrolytes are listed. Chemical etching is combined with treeing, an electrical breakdown process that starts when the dielectric strength is exceeded. These mechanical and electrical properties pertain to the dry plastics. The absorption of water molecules and electrolyte ions will cause these values to be reduced. Results and conclusions of the study are presented.
Date: January 1, 1977
Creator: Gammage, R.B. & Cotter, S.J.
Partner: UNT Libraries Government Documents Department

Indoor air and human health revisited: A recent IAQ symposium

Description: Indoor Air and Human Health Revisited was a speciality symposium examining the scientific underpinnings of sensory and sensitivity effects, allergy and respiratory disease, neurotoxicity and cancer. An organizing committee selected four persons to chain the sessions and invite experts to give state-of-the-art presentations that will be published as a book. A summary of the presentations is made and some critical issues identified.
Date: December 31, 1994
Creator: Gammage, R.B.
Partner: UNT Libraries Government Documents Department

Meeting regulatory standards with BeO ceramic TLD

Description: Measurements of exposures below 1 mR are possible with BeO ceramic TLD by signal recording that discriminates against an interfering pyroelectric incandescence. Performance under environmental monitoring conditions is considered in light of current regulatory criteria. Factors such as reproducibility and batch uniformity are satisfactory. An anomalous energy dependence causes an over-response that will probably require use of an energy compensation shield.
Date: January 1, 1978
Creator: Gammage, R.B. & Christian, D.J.
Partner: UNT Libraries Government Documents Department

Resolving the ambiguities: An industrial hygiene Indoor Air Quality (IAQ) symposium

Description: Resolving the Ambiguities: An Industrial Hygiene (IAQ) Symposium was a one-day event designed to inform practicing industrial hygienists about highlight presentations made at Indoor Air `93. A broad range of topics was presented by invited speakers. Topics included were attempts to deal with guidelines and standards, questionnaires, odors and sensory irritation, respiratory allergies, neuroses, sick building syndrome (SBS), and multiple chemical sensitivity (MCS).
Date: January 1, 1995
Creator: Gammage, R. B.
Partner: UNT Libraries Government Documents Department

Synthetic fossil fuel technologies: health problems and intersociety cooperation

Description: The potential health impacts of synthetic fossil fuel products are considered mainly in terms of complex and potentially carcinogenic mixtures of polynuclear aromatic (PNA) compounds. These components of oils and tars present an especially perplexing range of problems to those concerned with health protection. The nature of these problems, such as multifactorial exposure, are discussed within a framework of current and future standards to regulate human exposure. Some activities of government agencies, national laboratories, and professional societies are described. A case can be made for pooling the resources of these groups to achieve better solutions for assessing the acceptability of the various technologies and safeguarding human health.
Date: January 1, 1979
Creator: Gammage, R B & Turner, J E
Partner: UNT Libraries Government Documents Department

Effect of local geology on indoor radon levels: a case study

Description: This paper presents the results of radon monitoring in 40 East Tennessee homes that were a component of a larger study to evaluate indoor air quality. Measurements were conducted during two 3-month time periods with passive integrating track etch monitors in each of the forty homes. In a subset of homes, measurements were also conducted with a real-time monitor that provided readings on an hourly basis. The results of the monitoring indicate that about 30% of the homes had radon levels were associated with local variations in geology; most of the homes having higher levels were located on the porous dolomite ridge partially surrounding Oak Ridge, Tennessee. 7 references, 3 figures, 2 tables.
Date: January 1, 1984
Creator: Hawthorne, A.R.; Gammage, R.B. & Dudney, C.S.
Partner: UNT Libraries Government Documents Department

Normal and seasonally amplified indoor radon levels

Description: Winter and summer indoor radon measurements are reported for 121 houses in Freehold, New Jersey. When presented as winter:summer ratios of indoor radon, the data closely approximate a lognormal distribution. The geometric mean is 1.49. Freehold is located on the fairly flat coastal plain. The winter:summer ratios are believed to represent the norm for regions of the U.S. with cold winters and hot summers. The Freehold data set can be compared to corresponding data sets from other locations to suggest seasonal perturbations of indoor radon arising from unusual causes.
Date: January 1, 1995
Creator: Gammage, R.B.; Dudney, C.S.; Wilson, D.L. & King, D.
Partner: UNT Libraries Government Documents Department

Non-conventional passive sensors for monitoring tritium on surfaces

Description: The authors describe development of small passive, solid-state detectors for in-situ measurements of tritium, or other weak beta-emitting radionuclides, on surfaces. One form of detector operates on the principle of thermally stimulated exoelectron emission (TSEE), the other by discharge of an electret ion chamber (EIC). There are currently two specific types of commercially available detector systems that lend themselves to making surface measurements. One is the thin-film BeO on a graphite disc, and the other is the Teflon EIC. Two other types of TSEE dosimeters (ceramic BeO and carbon doped alumina) are described but lack either a suitable commercially available reader or standardized methods of fabrication. The small size of these detectors allows deployment in locations difficult to access with conventional windowless gas-flow proportional counters. Preliminary testing shows that quantitative measurements are realized with exposure times of 1--10 hours for the TSEE dosimeters (at the DOE release guideline of 5,000 dpm/100 cm{sup 2} for fixed beta contamination). The EIC detectors exhibit an MDA of 26,000 dpm/100 cm{sup 2} for a 24 hour exposure. Both types of integrating device are inexpensive and reusable. Measurements can, therefore, be made that are faster, cheaper, safer, and better than those possible with baseline monitoring technology.
Date: June 1, 1995
Creator: Gammage, R.B.; Brock, J.L. & Meyer, K.E.
Partner: UNT Libraries Government Documents Department

Radon levels inside residences in Mexico City

Description: Levels of radon were measured during winter and spring seasons inside 55 colonial and modern houses and 30 multifamily apartment buildings representative of middle and upper income families. The modern houses and apartment buildings in the southern section of the city had average radon levels exceeding 150 Bq m{sup {minus}3} with a maximum single measurement of 458 Bq m{sup {minus}3}. The colonial houses in the central downtown section had radon levels nearly all averaging below 100 Bq m{sup {minus}3}. Between the ground and third floor of the apartment buildings, radon levels diminished by tenfold indicating that entry of radon-bearing soil gas was largely responsible for the elevated concentrations of radon. The radon levels in winter exceeded by about 30% the radon levels during spring. The potentially adverse health effects of these radon levels may be exacerbated by the quality of air in Mexico City which during winter is often highly polluted. 7 refs., 2 figs.
Date: January 1, 1989
Creator: Espinoza, G. & Gammage, R. B.
Partner: UNT Libraries Government Documents Department

Transport studies of radon in limestone underlying houses

Description: In hilly limestone terrains of the southern Appalachians, subterranean networks of solution cavities and fissures present circulatory systems facilitating convective and advective transport of radon-bearing gas. Evidence suggests that the primary driving forces for transport are aerostatic pressure differentials created by the difference between the underground and the outside air temperatures. Examples are presented of houses experiencing elevated indoor radon levels as a consequence of communicating with such subsurface transportation systems. The location of a house near the upper or lower end of a subterranean-circulatory system seems to produce amplification of indoor radon levels in winter or summer, respectively. The transport mechanism for radon-bearing air in karst and its impact on indoor radon need better understanding, both in regard to evaluating the geographical prevalence of the phenomenon and the induced spatial and temporal effects that are possible. This paper reports field studies made at houses in karst regions at Oak Ridge, Tennessee, and Huntsville, Alabama. A primary radon-transport mechanism is advocated of ascending or descending subsurface columns of air whose flows are largely driven by aerostatic pressure gradients created by the inground-outdoor air temperature differentials. 5 refs., 5 figs., 1 tab.
Date: January 1, 1990
Creator: Gammage, R.B.; Dudney, C.S.; Wilson, D.L. & Saultz, R.J.
Partner: UNT Libraries Government Documents Department

Evaluation of polymers for fast neutron personnel dosimetry by the electrochemical etching technique

Description: Four plastics have been evaluated as potential fast neutron dosimeters, namely cellulose acetate, cellulose triacetate, cellulose acetobutyrate and polycarbonate. The technique of nuclear track registration in the plastics was used as the method of dosimetry.
Date: December 1, 1978
Creator: Johnson, S.A.; Ziemer, P.L.; Gammage, R.B. & Thorngate, J.H.
Partner: UNT Libraries Government Documents Department

Passive field monitoring of plutonium and americium in soil

Description: The authors` progress is described in applying passive alpha track detectors (ATDS) and electret ion chambers (EICS) to in-situ field monitoring of soils contaminated with particulate plutonium and americium at a desert site. By varying the exposure times, from a few minutes to about one day, they quantitatively measured alpha activity varying between {approximately} 100 pCi/g and {approximately} 100 nCi/g. Suggested applications are definition of the boundaries of contamination zones and verification that post-remediated soils are below release limits.
Date: December 31, 1994
Creator: Gammage, R. B.; Meyer, K. E. & Dudney, C. S.
Partner: UNT Libraries Government Documents Department

Field demonstrations of passive detectors for screening of alpha contaminated soils

Description: There are numerous sites around the country, DOE and otherwise, that are faced with the daunting task of remediating radiologically contaminated soils and groundwaters. Some of these sites, such as the Nevada Test Site and the Rocky Flats Plant, have contaminants that have been dispersed over wide areas. The costs of the characterization phase alone for such remediation programs can be prohibitive. Therefore there are pressing needs for testing and evaluation of new technologies for screening for radiological contaminants that may offer significant advantages in capital costs, ease of use, sensitivity, ruggedness, and/or reliability. This work reports on laboratory and Field tests of two types of passive alpha detectors, electret ionization chambers (EIC`s) and alpha track detectors (ATD`s), that have been commercially developed for indoor radon measurements. Previous work documented calibration and measurement protocols developed for these detectors for indoor surface contamination measurements.
Date: May 1, 1994
Creator: Meyer, K. E.; Gammage, R. B. & Dudney, C. S.
Partner: UNT Libraries Government Documents Department

Use of passive alpha detectors to screen for uranium contamination in a field at Fernald, Ohio

Description: This paper reports the results from a field test of newly developed techniques for inexpensive, in situ screening of soil for alpha contamination. Passive alpha detectors that are commercially available for the detection indoor airborne alpha activity (i.e., {sup 222}Rn) have been modified so they can be applied to the detection of alpha contamination on surfaces or in soils. Results reported here are from an intercomparison involving several different techniques with all measurements being made at the same sites in a field near the formerly used uranium processing facility at Fernald, Ohio, during the summer of 1994. The results for two types of passive alpha detector show that the quality of calibration is improved if soils samples are milled to increase homogeneity within the soil matrices. The correlation between laboratory based radiochemical analyses and quick, field-based screening measurements is acceptable and can be improved if the passive devices are left for longer exposure times in the field. The total cost per measurement for either type of passive alpha detector is probably less than $25 and should provide a cost-effective means for site managers to develop the information needed to find areas with remaining alpha contamination so resources can be allocated efficiently.
Date: June 1995
Creator: Dudney, C. S.; Meyer, K. E.; Gammage, R. B.; Wheeler, R. V.; Salasky, M. & Kotrappa, P.
Partner: UNT Libraries Government Documents Department

New generation of monitors for PAH's from synthetic fuel production

Description: A gap exists between the crude techniques available for measuring polynuclear aromatic (PNA) compounds in the workplace, and the sophisticated analytical tools used in the laboratory for a much more complete characterization of pollutants from synfuel operations such as coal, tar sand, and oil shale processing. Real-time or near-real instruments suitable for use by industrial hygienists are urgently needed to measure fugitive emissions. Several new instruments and instrumental techniques are described that could satisfy some of these needs. They include second derivative UV-absorption, synchronous luminescence, room-temperature phosphorescence, photoacoustic spectrometers, a portable mass spectrometer, differential sublimation, and thermoluminescence. Already, studies to evaluate the practicality of these approaches have indicated a suitability for monitoring naphthalene and its alkyl derivatives at parts-per-billion (ppB) concentrations either in the vapor or the solution phase, trace amounts of phenolic compounds, and thiocyanate in by-product water, and suitability for the rapid analysis of samples filtered or spotted on paper adsorbents.
Date: January 1, 1977
Creator: Gammage, R B; Vo-Dinh, T; Hawthorne, A R; Thorngate, J H & Parkinson, W W
Partner: UNT Libraries Government Documents Department

Evaluation of passive alpha detectors for sensitive/inexpensive/fast characterization of radiological contamination on surfaces and in soils

Description: Passive alpha-particle detectors, originally developed for indoor radon measurements, offer the potential for cost-effective and sensitive measurements of radiological contamination in soils and on surfaces for field screening and radiological survey applications. We have carried out field demonstrations of electret ionization chambers (EIC`s) and alpha track detectors (ATD`s). The EIC`s offer the advantages of immediate on-site readout, good sensitivity, ruggedness, and simplicity of operation. The use of parallel screened and unscreened EIC measurement allows the separation of alpha-particle response from radon/gamma/beta response. The advantages of the ATD`s include the potential for hot-particle counting, permanent records of contaminated and post-remediation activity levels, and inexpensive depth profiling of contamination in soil. At this time, the ATD`s are routinely shipped to the vendor after exposure in the field for processing and readout. It is feasible that the necessary processing and readout equipment could be deployed in a mobile laboratory for fast on-site analysis. We will present results from environmental measurements at the Nevada Test Site and indoor surface contamination measurements carried out at ORNL.
Date: April 1, 1994
Creator: Meyer, K. E.; Gammage, R. B.; Dudney, C. S.; Kotrappa, P.; Wheeler, R. & Salasky, M.
Partner: UNT Libraries Government Documents Department

Fiber-optic surface-enhanced Raman system for field screening of hazardous compounds

Description: Surface-enhanced Raman scattering permits identification of compounds adsorbed onto a metal microbase that is microlithographically produced with submicron resolution. Less than one percent of a monolayer of a Raman Active target compound offers a high signal-to-noise ratio. By depositing the microbase on the exterior of a fiber optic cable, convenient field screening or monitoring is permitted. By using highly effective microbases, it is possible to reduce laser power requirements sufficiently to allow an economical, but complete, system to be housed in a suitcase. We shall present details of SERS system of this type and shall show data on samples of interest in the screening of hazardous compounds.
Date: January 1, 1988
Creator: Ferrell, T.L.; Goudonnet, J.P.; Arakawa, E.T.; Reddick, R.C.; Gammage, R.B.; Haas, J.W. et al.
Partner: UNT Libraries Government Documents Department