Raymond Gold

Annealing phenomena in solid state track recorders

Abstract Accepted descriptions of the annealing process in Solid State Track Recorders (SSTR) are reviewed with emphasis on current misconceptions. In particular, it is shown that the Arrhenius equation should not be used to describe the decrease in observable track density induced by annealing. Results of annealing experiments in different SSTR media are examined. On this basis, a general reaction rate theory of the annealing process in SSTR is advanced. This formalism is used to introduce the new concept of the energy per etchable detect for SSTR. An important qualitative outgrowth of this work is the establishment of a general sensitivity-annealing correlation for SSTR. Observed annealing induced correlations between track size and track density for fission fragments are readily understood in terms of this general theory. Qualitative explanations of current enigmas in SSTR cosmic ray work are also advanced.

Proton and alpha particle response characteristics of CR-39 polymer for reactor and dosimetry applications

Proton and alpha particle response characteristics of CR-39 polymer for reactor and dosimetry applications have been investigated. The investigation included measurement of track etch rate as a function of proton and alpha particle energy. A calibration curve of track diameter versus proton energy is presented. The promising capabilities for reactor proton spectrometry and passive fast-neutron personnel dosimetry techniques are discussed.

Optical efficiency for fission-fragment track counting in Muscovite Solid-State Track Recorders

In order to determine absolute fission rates from thin actinide deposits placed in direct contact with Muscovite Solid-State Track Recorders, it is necessary to know the efficiency with which fission-fragment tracks are recorded. In this paper, a redetermination of the optical efficiency, i.e., the fraction of fission events recorded and observed in the Muscovite, is reported. The value obtained from a well-calibrated thin deposit of /sup 252/Cf and Muscovite etched about 90 min. in 49% HF at room temperature, is 0.9875 +- 0.0085. Manual counting was used. Preliminary results from a deposit of /sup 242/Pu are also reported, along with preliminary comparisons of track counting with an automated system. Reasons for the discrepancy of the optical efficiency reported here with an earlier measurement are also reported. 5 references, 1 figure, 3 tables.

The status of automated nuclear scanning systems

Abstract Present day minicomputers and microprocessors enable a range of automation, from partial to total, of tasks once thought beyond approach. The status of three computer controlled systems for quantitative track measurements is reviewed. Two systems, the Hanford optical track scanner (HOTS) and an automated scanning electron microscope (ASEM) are used for scanning solid state track recorders (SSTR). The third system, the emulsion scanning processor (ESP), is an interactive system used to measure the length of proton tracks in nuclear research emulsions (NRE). Current limitations of these systems for quantitative track scanning are presented. Experimental uncertainties attained with these computer controlled systems are described using results obtained from reactor neutron dosimetry.

Applications of solid state track recorder neutron dosimetry for fuel debris location in the three mile island unit 2 makeup and purification demineralizers

Abstract As a result of the Three Mile Island Unit 2 (TMI-2) accident on March 28, 1979, fuel debris was dispersed into the primary coolant and auxilliary systems of the reactor. The presence of fuel may be traced by using the neutron activity which is associated with the burn-in of higher actinides (about 300 neutrons/sec/kgU). Solid state track recorder (SSTR) neutron dosimetry is the most sensitive technique for measuring low neutron fluxes. Hence, neutron dosimetry is being performed at TMI-2 to locate fuel debris and subsequently aid the reactor recovery effort. Herein, the results of a scoping measurement on the fuel content of TMI-2 Makeup Demineralizer A are reported along with relevant calibration measurements. The total amount of fuel estimated in Demineralizer A, 1.7 kg, corresponds to a total neutron source of about 500 neutrons/sec. At the detector positions, data were obtained with neutron fluxes as low as 10-3 n/sec/cm2, demonstrating the extreme sensitivity of the SSTR method.

Solid-State Track Recorder Materials for Use in Light-Water-Reactor Pressure Vessel Surveillance Exposures

Solid-state track recorders (SSTR) have been used extensively in reactor neutron dosimetry. Further applications of SSTR in the U.S. breeder reactor, light water reactor, and magnetic fusion energy reactor programs have been planned. Extension of high-accuracy SSTR techniques to high-fluence irradiations requires careful attention to many experimental details. One very important aspect of this work is the selection of materials that comprise the SSTR. A variety of solid state track recorder materials has been examined for light-water-reactor pressure vessel surveillance applications. Emphasis has been placed on SSTR characteristics which are most relevant to high-fluence irradiations. The SSTR materials investigated include eleven different types of muscovite mica from worldwide geographical locations and different commercial suppliers, synthetic and natural quartz crystals, and quartz glass. Activatable impurities are appreciable only in the case of mica SSTR, and relative isotopic impurity concentrations are reported. Fissionable impurity concentrations in mica and quartz are also reported. The properties of mica and quartz SSTR subjected to high-fluence (3 X 10 2 1 neutrons (n)/cm 2 ), high-temperature [427°C (800°F)] irradiations have been investigated. Recommendations regarding suitable types of mica and quartz are made.

APPLICATIONS OF SOLID STATE TRACK RECORDERS IN UNITED STATES NUCLEAR REACTOR ENERGY PROGRAMS

The domain of Solid State Track Recorder (SSTR) applications in United States nuclear reactor energy programs extends from the harsh high temperature environments found in high power reactor cores to very low flux environments arising in out-of-core locations, critical assemblies, or away from reactors (AFR) experiments. The neutron energy region arising in these applications is very broad, covering more than eight decades from thermal up to fusion energies. The range of neutron flux/fluence intensity is even greater, extending over more than thirteen decades. As a consequence, use of a variety of SSTR is entailed in U.S. Fast Breeder Reactor (FBR), Light Water Reactor (LWR), and Magnetic Fusion Energy Reactor (MFER) programs. A summary status is presented of selected SSTR experiments undertaken in these programs at the Hanford Engineering Development Laboratory (HEDL).

Buffon needle method of track counting

A new technique of quantitative track counting, the Buffon needle method, is advanced. It is based on random sampling of the solid state track recorder (SSTR) surface. This new method extends quantitative track scanning to track densities well up into the track pile-up regime. It is shown that the Buffon needle method possesses a reduced dependence upon both track density nonuniformity and track size distribution. Sources of experimental error arising in the Buffon needle method are assessed. The validity of the Buffon needle method is demonstrated down to at least the 10% uncertainty level (1sigma) by manual sampling of high fission track density mica SSTR observed with scanning electron microscopy.

Residual stresses associated with the hydraulic expansion of steam generator tubing into tubesheets

Abstract Various methods are being used to expand heat transfer tubes into the thick tubesheets of nuclear steam generators. The residual stresses in the as-expanded tubes and methods for reducing these stresses are important because of the role which residual stresses play in stress corrosion cracking and stress assisted corrosion of the tubing. Of the various expansion processes, the hydraulic expansion process is most amenable to analytical study. This paper presents results on the residual stresses and strains in hydraulically expanded tubes and the tubesheet as computed by two different finite element codes with three different finite element models and by a theoretical incremental analysis method. The calculations include a sensitivity analysis to assess the effects of the expansion variables and the effect of stress relief heat treatments.

Application of solid state track recorder neutron dosimetry for three mile island unit 2 reactor recovery

Abstract Application of neutron dosimetry for assessment of fuel distribution throughout the Three Mile Island-2 (TMI-2) reactor core region and the primary coolant system is advanced. Neutron dosimetry in the reactor cavity, i.e. the cavity between the pressure vessel and the biological shield, could provide data for the assessment of the core fuel distribution. A more immediate task entails locating and quantifying the amount of fuel debris in the ex-core primary coolant system in the range of 1 to 1000 kg. Solid state track recorder (SSTR) neutron dosimetry is considered for such exploratory scoping experiments at TMI-2. The sensitivity of mica- 2 3 5 U (asymptotically thick) SSTR has been ascertained for such environments. For plausible geometric assumptions and environmental conditions, it has been demonstrated that the SSTR method has adequate sensitivity to properly respond and detect fuel quantities of the order of 1 kg in the ex-core primary coolant system.