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Nuclear Data Sheets for A = 224

The experimental nuclear spectroscopic data for ten experimentally known nuclides of mass number 224 (Bi, Po, At, Rn, Fr, Ra, Ac, Th, Pa, U) have been evaluated and presented together with the Adopted properties for levels and γ rays. For {sup 224}Bi, {sup 224}Po, {sup 224}At, {sup 224}Rn, {sup 224}Fr, {sup 224}Pa and {sup 224}U nuclei, only the ground–state information is known. Half–lives of ground states of 224Bi and 224Po have not yet been measured. The decay of {sup 224}Rn to {sup 224}Fr has been studied, but no decay scheme has been proposed. The decay of {sup 224}Ac to {sup 224}Ra is reported only in an abstract style conference proceedings. For a definite Jπ assignment for ground state of {sup 224}Ac, a detailed study of this decay may be helpful. In the decay of {sup 228}Pa to {sup 224}Ac, authors of 1994Ah03 state that the lowest state observed in their work may not be the ground state. Thus an extensive study of {sup 228}Pa α decay, and studies involving nuclear reactions are warranted since the level scheme of {sup 224}Ac presented in this evaluation is considered as incomplete due to the lack of confirmed information about multipolarities, mixing ratios and other spectroscopic details. Three new nuclides {sup 224}Bi, {sup 224}Po, and {sup 224}At are added in this revision, together with new in–beam γ–ray and Coulomb excitation data for {sup 224}Ra. Although, not much new experimental data have appeared since the previous evaluation (1997Ar05), extensive modifications have been made in almost all the datasets. This work supersedes the information presented in the previous NDS evaluations of A = 224: 1997Ar05, 1986Ma45 and 1976El05.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

A multi-method approach for groundwater resource assessment in coastal carbonate (karst) aquifers: the case study of Sierra Almijara (southern Spain)

Understanding the transference of water resources within hydrogeological systems, particularly in coastal aquifers, in which groundwater discharge may occur through multiple pathways (through springs, into rivers and streams, towards the sea, etc.), is crucial for sustainable groundwater use. This research aims to demonstrate the usefulness of the application of conventional recharge assessment methods coupled to isotopic techniques for accurately quantifying the hydrogeological balance and submarine groundwater discharge (SGD) from coastal carbonate aquifers. Sierra Almijara (Southern Spain), a carbonate aquifer formed of Triassic marbles, is considered as representative of Mediterranean coastal karst formations. The use of a multi-method approach has permitted the computation of a wide range of groundwater infiltration rates (17–60%) by means of direct application of hydrometeorological methods (Thornthwaite and Kessler) and spatially distributed information (modified APLIS method). A spatially weighted recharge rate of 42% results from the most coherent information on physiographic and hydrogeological characteristics of the studied system. Natural aquifer discharge and groundwater abstraction have been volumetrically quantified, based on flow and water-level data, while the relevance of SGD was estimated from the spatial analysis of salinity, {sup 222}Rn and the short-lived radium isotope {sup 224}Ra in coastal seawater. The total mean aquifer discharge (44.9–45.9 hm{sup 3} year{sup −1}) is in agreement with the average recharged groundwater (44.7 hm{sup 3} year{sup −1}), given that the system is volumetrically equilibrated during the study period. Besides the groundwater resources assessment, the methodological aspects of this research may be interesting for groundwater management and protection strategies in coastal areas, particularly karst environments.

58 GEOSCIENCES↗

Testing a Hazmatpac Can with Locking Ring as a Secondary Shipping Container for Radium-224/Lead-212 Generators

A Hazmatpac can, paint can style shipping container with locking ring, was tested for use as an alternative shipping configuration for shipment of radium- 224 /lead- 212 generators. 224 Ra ( t 1/2 = 3.63 d) decays by alpha emission to radon-220 ( t 1/2 = 55.6 s). The potential for the radioactive radon gas to escape the generator column and the shipping container is of particular concern for the safe delivery of 224 Ra/ 212 Pb generators to customers. The purpose of this study was to evaluate whether the Hazmatpac can is a suitable shipping configuration, capable of containing the radon gas that may escape the generator column during transit. A 17.3 mCi 224 Ra/ 212 Pb generator was built and packaged into a Hazmatpac can. The can was smeared by a Radiological Control Technician (RCT) every day for seven days to analyze for radioactive contamination on the outside of the can. Over the course of the study, no radioactive contamination was found on the outside of the can. Therefore, the Hazmatpac can was approved as an alternative shipping configuration for shipment of 224 Ra/ 212 Pb generators.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗