Specific Fission Research Articles

Measurement of power and burn-up in irradiated nuclear reactor fuel by a non-destructive method

A simple non-descructive test for measuring power and burn-up in irradiated nuclear reactor fuel is described. The method involves scanning the fuel elements via a slit in shielding for the gamma activity of two specific fission products. A short half-life fission product gives a measure of power production in the fuel for the period immediately prior to discharge, whilst a long half-life product gives a measure of the power integrated over the whole irradiation period. Calibration of the system by standard sources or radio-chemical analysis enables actual values of power and burn-up, as well as distribution, to be obtained.

Airborne radioactivity due to nuclear weapons tests

Samples of Surface air collected at Argonne National Laboratory since early 1952 have been analyzed for specific fission products by NaI scinti llati on spectrometry. The W/sup 181/ and Rh/sup 102/ produced in the Hardtack series (1958) have been used to assign nuclear debris to the low- and high-altitude phases of this series, respectively. Activity ratios between appropriate radionuclides have been used to determine the portion of total debris arising from the Soviet October 1958 series. The differences in mean stratospheric residence time as a function of lati tude and altitude of injection, as deduced from these data, are discussed in detail. (auth)

Correlations between the Neutron Multiplicities and Spontaneous Fission Modes of Californium-252

The numbers of prompt neutrons associated with specific fission modes of ${\mathrm{Cf}}^{252}$ have been measured. The average number of neutrons per fission depends largely upon the total kinetic energy of the fission fragments, decreasing by at least 0.06 neutron per fission for an increase of 1 Mev in the total kinetic energy. A less marked variation with the ratio of fragment masses is observed.

407. Studies on specific chemical fission of peptide links. Part II. The preparation and hydrolysis of 1-acylpyrrolid-2-ones derived from α-glutamyl peptides

407. Studies on specific chemical fission of peptide links. Part II. The preparation and hydrolysis of 1-acylpyrrolid-2-ones derived from α-glutamyl peptides

Range and Range Dispersion of Specific Fission Fragments

The range and dispersion in range of specific ${\mathrm{U}}^{233}$ and ${\mathrm{U}}^{235}$ fission fragments; namely, those associated with delayed-neutron emitters, have been determined in gases of different atomic number. These measurements give the $Z$-dependence of the range and range dispersion for fragments associated with a specific mode of fission. After corrections for foil thickness and geometry the $Z$-dependent part of the range dispersion which arises from the nuclear stopping process was determined and values were obtained for the residual component corresponding to the energy dispersion associated with the fission process itself. The values thus obtained for this energy dispersion are found to be in fair accord with recent theoretical results of Fong.

THE ACTION OF SULPHURIC ACID ON GLIADIN: WITH SPECIAL REFERENCE TO THE N-PEPTIDYL→O-PEPTIDYL BOND REARRANGEMENT

Treatment of gliadin with sulphuric acid transposes peptide bonds of serine from the amino to the hydroxyl group. Maximum transposition, 60–70% of the theoretical, occurs when the protein is treated with anhydrous sulphuric acid at 0°C. for 35 hr. No rearrangement was detected at threonine residues. Examination of the peptide material, obtained from the rearranged protein by Elliott's degradation method, indicates apparent "homogeneity". In an alternative scheme for the degradation, nitrous acid deamination of free amino groups was used. The resulting loss in serine content of the protein is direct evidence for the acyl migration of peptide bonds. Incorporation of sulphur and partial disappearance of several amino acids accompany the sulphuric acid treatment. The occurrence of these secondary reactions imposes limitations on the use of sulphuric acid as a reagent for the specific fission of peptide bonds.