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Calculations were performed to support method development for simultaneous production of Ni and Ir isotopes. The work scope included development of the physical target, irradiation configuration, and post-irradiation radiochemical separations. The assumptions of predictive models previously developed were refined based upon the precise experimental configuration selected, including Os target material and a set of stacked targets for concurrent production of Ni and Ir isotopes. Model predictions of the reaction cross sections with EMPIRE 3.2 (Herman in Nuclear Data Sheets 108:2655–2715, 2007) and implied isotopic yields are compared with proton beam irradiation measurements to refine model parameters and guide future experiments.

The measurement of radioactive fission products from nuclear events has important implications for nuclear data production, environmental monitoring, and nuclear forensics. In a previous paper, the authors reported the optimization of an intra-group lanthanide separation using LN extraction resin from Eichrom Technologies®, Inc. and a nitric acid gradient. In this work, the method was demonstrated for the separation and quantification of multiple short-lived fission product lanthanide isotopes from a fission product sample produced from the thermal irradiation of highly enriched uranium. The separations were performed in parallel in quadruplicate with reproducible results and high decontamination factors for 153Sm, 156Eu, and 161Tb. Based on the results obtained here, the fission yields for 144Ce, 153Sm, 156Eu, and 161Tb are consistent with published fission yields. This work demonstrates the effectiveness of the separations for the intended application of short-lived lanthanide fission product analysis requiring high decontamination factors.

Uncertainties associated with short lived (half-lives less than 1 day) fission product yields listed in databases such as the National Nuclear Data Center’s ENDF/B-VII are large enough for certain isotopes to provide an opportunity for new precision measurements to offer significant uncertainty reductions. A series of experiments has begun where small samples of 235U are irradiated with a pulsed, fission neutron spectrum at the Nevada National Security Site and placed between two broad-energy germanium detectors. The amount of various isotopes present immediately following the irradiation can be determined given the total counts and the calibrated properties of the detector system. The uncertainty on the fission yields for multiple isotopes has been reduced by nearly an order of magnitude.

A new metal matrix composite material has been developed to serve as a thermal neutron absorber for testing fast reactor fuels and materials in an existing pressurized water reactor. The performance of this material was evaluated by placing neutron fluence monitors within shrouded and unshrouded holders and irradiating for up to four cycles. The monitor wires were analyzed by gamma and X-ray spectrometry to determine the activities of the activation products. Adjusted neutron fluences were calculated and grouped into three bins—thermal, epithermal, and fast—to evaluate the spectral shift created by the new material. A comparison of shrouded and unshrouded fluence monitors shows a thermal fluence decrease of ~11 % for the shielded monitors. Radioisotope activity and mass for each of the major activation products is given to provide insight into the evolution of thermal absorption cross-section during irradiation. The thermal neutron absorption capability of the composite material appears to diminish at total neutron fluence levels of ~8 × 1025 n/m2. Calculated values for dpa in excess of 2.0 were obtained for two common structural materials (iron and nickel) of interest for future fast flux experiments.

A dosimetry experiment used to measure the neutron flux and spectrum of a D-T neutron generator is presented. The D-T generator at Pacific Northwest National Laboratory is installed in the middle of a large room to minimize scatter of neutrons back to the sample. The efficacy of maintaining a pure fast neutron field for the sample is investigated. Twenty-one positions within 13 cm of the neutron source contained foils or wires of Fe, Ni, and Al with additional Au, and in monitors at some locations. Spectral adjustment of the neutron flux at each position based on the measured reaction rates and theoretical Monte Carlo calculations show that at least 99.1% of the spectrum lies above 110 keV for all measured positions, and neutrons above 14 MeV can account for as much as 91% at locations along the axis of the generator and close to the source. The 14 MeV component drops to 77% in radial positions far from the source. The largest total flux observed was 8.29E+08 n/cm 2 s (±1.4%) in the center of the cooling cap, although additional experiments have shown this value could be as high as 1.20E+09 n/cm 2 s.

• This workshop had an attendance of about 15 participants. • On calculation discrepancies of gamma heating and DPA in stainless steel or low carbon steel with high depth inside EPR, a question was raised on how to benchmark TRIPOLI with experimental heating techniques. The experiences with heating measurements at Cadarache with special differential calorimeters were discussed. The importance of these measurements concerning JHR (need to define) was mentioned. • On the implementation of mass spectrometric techniques in measuring stable products in dosimeters, experience in precisely carrying out the measurements was addressed. One of the issues is that the initial sample needs a careful characterization to make sure that transmuted isotopes exceed the level of the starting impurities. In general, stable isotopes can be measured reliably. As an example, the production of helium due to the transmutation of 58Ni to 59Ni (which has a high thermal neutron (n, ) cross section) and 10B has been cited, a phenomenon that is famous within the fusion community due to the high production of helium similar to fusion reactor conditions. Although these transmutations were very well studied, some discrepancies were noticed under very high fluence conditions. An ongoing experiment at Cadarache to address high Helium production in the VVER’s has been cited. • Difficulties related to mixed neutron/gamma field measurements, especially owing to the lack of measured photon spectra, were discussed. New techniques are needed to reliably measure the gamma spectra in reactors separately from the neutron spectra. • On the issue of modeling secondary gammas, the capability of the newest MCNP version in taking this effect into account was addressed. • On the issue of availability of alloyed dosimeters for high temperature applications (Co-V alloys for instance), the participants agreed upon looking out for a manufacturer who could deliver such products. This is a general problem since many useful dosimeters are no longer being produced such as depleted uranium and 237Np fission monitors. The reactor dosimetry community needs to push this issue with potential sources of such materials, such as Oak Ridge National Lab in the US or IRMM, Geel. It is also nearly impossible to obtain 252Cf which is very useful for testing of reactor dosimetry reactions, as cited in recent work by the IAEA in the validation of the IRDFF evaluated cross section library for reactor dosimetry. • On the issue of fluorescence effects in the measurement of the reaction product 93mNb, the filter paper technique, coupled to x-ray measurements, is deemed to provide good results while

A description of the neutron fluence analysis of activated zirconium alloys samples at a Westinghouse 3-loop reactor is presented. These samples were irradiated in the core and in the fuel plenum region, where dosimetry measurements are relatively rare compared with regions radially outward of the core. Dosimetry measurements performed by Batelle/PNNL are compared to the calculational models. Good agreement is shown with the in-core measurements when using analysis conditions expected to best represent this region, such as an assembly-specific axial power distribution. However, the use of these conditions to evaluate dosimetry in the fuel plenum region can lead to significant underestimation of the fluence. The use of a flat axial power distribution, however, does not underestimate the fluence in the fuel plenum region.

A multibubble standing wave pattern can be generated from an acoustic wave reflected from a flat surface. By adding a second transducer at 90 deg from the transducer generating the standing wave, a three‐dimensional volume of stable single bubbles can be established. Further, the addition of the second transducer operating at the same frequency stabilizes the bubble pattern so that individual bubbles may be studied. The size of the bubbles and the separation of the standing waves depend on the frequency of operation. Two transducers, operating at frequency of 630 kHz, provided the most consistent results for the configuration used in this study. The bubbles exhibit bright sonoluminescence. Spectral measurements are in progress. Effect of the shape of the configuration will be discussed along with the standing wave patterns, spectral data, and pictorial results of separation of individual bubble sonoluminescence in a multibubble sonoluminescence environment.

Single bubble sonoluminescence (SBSL), multi‐bubble sonoluminescence (MBSL), multi‐bubble sonochemiluminescence (MBSCL) and other high power ultrasound cavitation and noncavitating ultrasound process stream interaction phenomena are known to produce a wide range of both physical and chemical effects that depend upon the system and operating conditions employed. Three interacting regimes are under investigation (a) high power and high frequency (including noncavitating systems), (b) single bubble resonance/sonoluminescence and (c) multi‐bubble high power sonochemical processing. In all cases these involve various reactors, including possible schemes for continuous material feeding and processing for selected chemical, nonaqueous fluids and biological research and industrial applications. High power sonochemical and noncavitating ultrasound processing applications and a review of literature pertaining to the potential of high power processing, including fusion are discussed. Work includes the investigation of acoustic fields in reactors, characterization of sonoluminescence spectra, the investigation of system parameters to control maximum bubble temperature and pressure, and acoustic energy partition into light and acoustic emission/shock waves. Effects of various chemical systems on multi‐bubble luminescence are being investigated and will be reported. Work to date has emphasized the evaluation of both single and multi‐bubble sonoluminescence, spectral measurements, acoustic emission measurements and the observation of a continuous bubble feed phenomenon.

The 27Al(n,2n)26Al reaction is of considerable interest to the fusion reactor program. Aluminum is an attractive material for many structural applications and the (n,2n) reaction is the major source of long-lived activity (26Al, g.s. T12 = 7.34 × 105 y). The threshold for this reaction falls within the spread of neutron energies generated by a D-T plasma. Its cross section is therefore a steeply rising function of energy for the primary fusion neutrons. This special feature makes it possible to use this reaction to measure plasma ion temperatures as well as neutron yields and neutron spectral shapes. The above applications require accurate measurements of the 27Al(n,2n)26Al cross section near threshold, but no data was available in the 14–15 MeV energy range of interest so a series of experiments1,2 were performed using aluminum samples irradiated at the neutron sources at LLL (RTNS-II), 3,4 and at PPL (electrostatic generator).2 In some experiments the new technique of accelerator mass spectrometry1,5 was used to measure the production rate of 26A1. The new measurements1 suggest that most of the (n,2n) yield near threshold is associated with the direct production of the 3+ state of 416.9 keV rather than the 5+ ground state. This raises the Q-value and neutron threshold energy for this reaction by a similar amount and greatly reduces the effective cross section of the (n,2n) reaction for D-T fusion neutrons. The effective cross section for a 9 keV D-T plasma is reduced by a factor of 5 by this shift in Q-value. A similar reduction occurs for the long-lived radioactivity.

Diameter-age relationships of two species of mountain mahogany (true mountain mahogany and curlleaf mountainmahogany) were investigated. Data were taken from populations of true mountain mahogany in the Laramie Basin of Wyoming (Brooks 1962) and the Uintah Basin of Utah. Data for curlleaf mountain mahogany were obtained from populations in the Whitehorse mountains of Oregon, the Trout Creek mountains of Nevada (Dealy 1975) and from several areas in north-central Utah. Equations were developed for age prediction from stem diameters. Age prediction was most accurate within local population boundaries and less so when used to predict ages across population boundaries. Aspect was shown to be an important factor in influencing age prediction in curlleaf mountain mahogany. Variations in the growth rings of trees and shrubs have been used for years as dating techniques (Douglas 1935; Glock 1937) and to gain information about climatic differences of the past (Schulman 1956; Fritts 1971; Stockton and Meko 1975; Harper 1979). Ring-width variations have also been used to assess differences in the environments of selected habitats (Ferguson and Humphrey 1959; Fritts 1962; Stockton and Fritts 1973; Fritts 1974). Although trees have been the major object of such studies (Glock 1955; Authors are associate professor of botany and range science, Department of Botany and Range Science, Brigham Young University, Provo, Utah 84602; research scientist, Shrub Sciences Laboratory, U.S. Forest Service, Provo, Utah 84601; and range conservationist, Bureau of Land, Richfield, Utah 84701. Manuscript received March 30, 1979. JOURNAL OF RANGE MANAGEMENT 33(5), September 1980 Argeter and Glock 1965) papers dealing with shrubs can also be found (Ferguson 1958; Ferguson 1959; Ferguson and Humphrey 1959). The shrub studies have generally dealt with variations of moisture in the habitat or as aids to archaeological interpretation. Studies dealing with diameter-age relationships of shrubs and their values in the development of age-prediction models, interpretations of environmental factor differences, site-quality estimates, and measurements of successional trends are generally lessknown. The objectives of this study were: to assess the stem diameter-age relationships in true mountain mahogany (Cercocarpus montanus) and curlleaf mountain mahogany (Cercocarpus Zedifolius), to develop age prediction models from stem diameters, to assess the accurateness of the models within and between populations, and to evaluate the effects of aspect on the growth patterns of the shrubs and thus the predictive value of the models.