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The investigation of giant resonances, other than electric dipole, has been accomplished with various nuclear probes. Electron scattering and hadron scattering have been used most often for this purpose. The photonuclear cross sections associated with multipoles higher than dipole are very small so that photon scattering would seem an unlikely method of studying the electric quadrupole giant resonance. However, an appreciable E1-E2 interference term in the angular distribution permits the observation of E2 strength. In this Letter, we report on the use of elastically Phys. Rev. Lett. _36, 307 (1976).scattered photons to determine the location and magnitude of the E2 strength in 12 C. Scattering cross sections were measured at 90° and 135° in the energy range from 23.5 to 39 MeV and the results compared to the predicted values derived from the measured photonuclear absorption cross section. 1 The results show that for excitation energies below 24 MeV only electric dipole transitions need be considered, but in the energy range from 24 to 40 MeV, the magnitude of the electric quadrupole absorption is surprisingly large. The elastic-scattering cross section is meas-The elastic-photon-scattering cross section for 2 C has been measured at 90° and 135° in the energy range from 23.5 to 39 MeV. These data disagree with the predicted scattering, derived from the measured photonuclear absorption cross section, if only El transitions are assumed. To explain the difference in these cross sections, a large component of electric quadrupole absorption between 24 and 40 MeV is inferred.

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Results of scenario identification, preparation of reliability data, fault tree construction and its analysis, are rendered for a system anomaly considered liable to lead to a red oil explosion in a Pu evaporator of a typical model of reprocessing facility. Japan Atomic Energy Research Institute has introduced the model plant data, the basic failure frequency data together with the fault tree analysis code FTL from NUKEM GmbH, Germany, and used to execute the above analyses.'The frequency of occurrence of the system anomaly initiated by failures of the Pu purification process such as a pulse column failure or a mixer settler failure has been evaluated to be 2 . 6~l O -~/ y r for the solvent carry over into the evaporator for the German model reprocessing facility. In addition to this event, if an abnormal state such a s continuously heating the solution to over 150°C inside the evaporator would happen with the analyzed occurrence probability of 1 . 0~1 0 -~, it would be the more possible to result in the red oil explosion. The occurrence frequency for the combined events has been calculated to be 2.6 x 10-"/yr, so small compared with the public acceptance limit which might be set as 1 x lO-O/yr.