[en] Equipment has been set up for the preparation of UF₄ and PuF₃. Conventional vacuum evaporation systems devised with multi-substrates fixtures allowing simultaneous preparation of a considerable number of deposits have been evaluated. The resulting actinide deposits are intercalibrated by relative alpha counting and characterized by isotope dilution mass spectrometry (IDMS). The paper reports on the achievement on ²³⁹Pu deposits. The paper also gives information concerning the availability at CBNM of potential neutron dosimeter alloys containing certified amounts of fissile material

[en] The paper reviews the requirements for a surveillance capsule program including types of mechanical property and neutron dosimetry specimens. Typical facilities used in a hot laboratory for testing specimens are presented. The types of data generated from mechanical property and neutron dosimetry specimens are discussed. In addition, the manner in which the generated data is evaluated and applied to a plant is described

[en] The report attempts to present a brief, but comprehensive review of the status and future directions of benchmark neutron field development, characterization and application in perspective with two major objectives of reactor dosimetry: (1) fuel fission rate and burn-up passive monitoring, and (2) correlation of materials irradiation damage effects and projection to commercial power plants. The report focuses on the Light Water Reactor and Fast Breeder Reactor program needs

[en] Relative fission yields were measured for three different locations in the row 4 ''Test Region'' of the EBR-II reactor. Correlation of the relative fission yields to the measured average energy (anti E) and the measured ¹³⁷Cs ²³⁸U/²³⁵U spectral indices have been made. The measured relative fission yields for selected fission products from ²³⁵U, ²³⁸U, ²³⁹Pu and ²³⁷Np have been compared with those values reported by the Interlaboratory Reaction Rate (ILRR) program, EBR-II fast reactor yields from destructive analysis and summation, and the March 1977 version of ENDF/B-V

[en] The status of fission yield data is briefly reviewed. Problems associated with the evaluation and compilation of fast reactor fission yields are discussed. A new approach for evaluating the change in fission yields with neutron energy is presented. Based on a comparison of relative isotopic abundances rather than absolute yield data, changes of only a few percent in the isotopic abundances of the neodymium isotopes as a function of neutron energy are easily detected

[en] The mass-yield distribution for the neutron-induced fission of ²³⁸U by degraded fission spectrum neutrons with an average energy of 1.52 MeV has been measured radiochemically for 26 mass chains in the region A = 89 to 153. Germanium-lithium gamma-ray spectroscopy coupled with beta-particle counting techniques was used to determine the absolute activities of each nuclide measured. The absolute cumulative fission yield of mass chain 140 (¹⁴⁰Ba-¹⁴⁰La) was determined to be 6.07 +- 0.24, and all other reported yields were measured relative to that value. Measured yields ranged from a maximum of 6.33 +- 0.55 for ¹⁰³Ru on the light mass wing and 6.54 +- 0.28 for ¹³³I on the heavy mass wing to a minimum of 0.030 +- 0.007 for ¹²¹Sn in the valley region. Results from this investigation provide a consistent set of cumulative mass yields from ²³⁸U fission induced by a well-characterized neutron spectrum

[en] The objectives and requirements for dosimetry benchmark neutron fields were defined at the IAEA Consultants' Meeting on Integral Cross-Section Measurements in Standard Neutron Fields, Vienna 1976, (INDC(SEC)-54/L+Dos., INDC(NDS)-81/L+M). The following list reviews the work on benchmark neutron fields and their applications at the PTB

[en] Several neutron fields whose absolute intensity and spectrum are known sufficiently well to serve as calibration facilities for reactor dosimetry are now operational at NBS. These include a fission-neutron spectrum generated by a small point source of ²⁵²Cf (phi approximately 1.5 x 10⁷ n/cm² sec at 5 cm distance), an intermediate-energy standard neutron field (ISNF) at the center of a spherical cavity in the thermal column of the NBS reactor (phi approximately 10⁹ n/cm²-sec), and a near-1/E spectrum in the same location with about twice that flux. For the ²⁵²Cf facility recent investigations are discussed such as intercomparison of source strength with other laboratories, response of integral detectors in this spectrum, and evaluation of the differential spectrum. The ISNF facility is described, and some preliminary integral measurements are discussed

[en] With a view to estimate some unknown dose values together with their accuracy from a set of foil data, a new data processing technique is presented. The technique is based on a variational representation of the dose quantity. The present technique is thought to give an approximate solution to the maximum liklihood method based on the Bayes' theorem and is also regarded as a modified FERDO method for the foil data unfoldings. Another feature of this formulation is shown in discussions of the efficient detector calibration in some standard neutron field, where a new concept ''calibration-efficiency'' is introduced through a particular error analysis of the calibration procedure

[en] Foils of various fissile and nonfissile materials commonly used in neutron dosimetry have been irradiated in the CFRMF, Idaho and Big-10 Los Alamos. Following these irradiations quantitative γ-ray counting was undertaken by five separate groups at four laboratories. Each group used independently calibrated γ-ray detectors; either Ge(Li) or NaI(Tl). These measurements were made as a part of the Interlaboratory Reaction Rate (ILRR) program. Intercomparison of the reaction rate values obtained by each group show good consistency, with individual variations from the average reaction rates generally being less than +-2%. Based upon this consistency and the estimated uncertainties in the nuclear decay parameters the absolute accuracies of these reaction rates are estimated at +-2% (1 sigma). Integral cross section values have been deduced for these reactions in CFRMF and Big-10