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All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Nuclear Data Sheets for A=170☆

Nuclear structure data pertaining to all nuclei with mass number A=170 have been evaluated, and incorporated into the ENSDF data file. This evaluation supersedes the previous evaluation (Coral M. Baglin), Nuclear Data Sheets 96, 611 (2002), (cutoff date 15 August 2002) and subsequent updates of the ENSDF file for Yb to Dy (cutoff 15 April 2010), Lu (cutoff 8 October 1998), Pt (cutoff 17 February 1999) and Ta, Os (cutoff 7 April 1998). Since the previous evaluation, {sup 170}Gd has been observed and the ground state T{sub 1/2} measured. New excited states have also been observed in the neutron rich {sup 170}Dy. The ground state T{sub 1/2} of {sup 170}Tb has been determined, however, there are currently still no excited states observed in this nucleus. There remains some uncertainty in the ground state and longer-lived isomer in {sup 170}Ir which could warrent further experimental investigation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

Comparative analysis of 11 different radioisotopes for palliative treatment of bone metastases by computational methods

Purpose: Throughout the years, the palliative treatment of bone metastases using bone seeking radiotracers has been part of the therapeutic resources used in oncology, but the choice of which bone seeking agent to use is not consensual across sites and limited data are available comparing the characteristics of each radioisotope. Computational simulation is a simple and practical method to study and to compare a variety of radioisotopes for different medical applications, including the palliative treatment of bone metastases. This study aims to evaluate and compare 11 different radioisotopes currently in use or under research for the palliative treatment of bone metastases using computational methods. Methods: Computational models were used to estimate the percentage of deoxyribonucleic acid (DNA) damage (fast Monte Carlo damage algorithm), the probability of correct DNA repair (Monte Carlo excision repair algorithm), and the radiation-induced cellular effects (virtual cell radiobiology algorithm) post-irradiation with selected particles emitted by phosphorus-32 ({sup 32}P), strontium-89 ({sup 89}Sr), yttrium-90 ({sup 90}Y ), tin-117 ({sup 117m}Sn), samarium-153 ({sup 153}Sm), holmium-166 ({sup 166}Ho), thulium-170 ({sup 170}Tm), lutetium-177 ({sup 177}Lu), rhenium-186 ({sup 186}Re), rhenium-188 ({sup 188}Re), and radium-223 ({sup 223}Ra). Results: {sup 223}Ra alpha particles, {sup 177}Lu beta minus particles, and {sup 170}Tm beta minus particles induced the highest cell death of all investigated particles and radioisotopes. The cell survival fraction measured post-irradiation with beta minus particles emitted by {sup 89}Sr and {sup 153}Sm, two of the most frequently used radionuclides in the palliative treatment of bone metastases in clinical routine practice, was higher than {sup 177}Lu beta minus particles and {sup 223}Ra alpha particles. Conclusions: {sup 223}Ra and {sup 177}Lu hold the highest potential for palliative treatment of bone metastases of all radioisotopes compared in this study. Data reported here may prompt future in vitro and in vivo experiments comparing different radionuclides for palliative treatment of bone metastases, raise the need for the careful rethinking of the current widespread clinical use of {sup 89}Sr and {sup 153}Sm, and perhaps strengthen the use of {sup 223}Ra and {sup 177}Lu in the palliative treatment of bone metastases.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Radionuclide transport in brackish water through chalk fractures

Mobility of radionuclides originating from geological repositories in the subsurface has been shown to be facilitated by clay colloids. In brackish water, however, colloids may flocculate and act to immobilize radionuclides associated with them. Furthermore, little research has been conducted on radionuclide interactions with carbonate rocks. In this work, the impact of bentonite colloid presence on the transport of a cocktail of U(VI), Cs, Ce and Re through fractured chalk was investigated. Flow-through experiments were conducted with and without bentonite colloids, present as a mixture of bentonite and Ni-altered montmorillonite colloids. Ce was used as an analogue for reactive actinides in the (III) and (VI) redox states, and Re was considered an analogue for Tc. Filtered brackish groundwater (ionic strength = 170 mM) pumped from a fractured chalk aquitard in the northern Negev Desert of Israel, was used as a solution matrix. Rhenium transport was identical to that of the conservative tracer, uranine. The sorption coefficient (K d ) of U(VI), Cs and Re, calculated from batch experiments with crushed chalk, proved to be a good predictor of mass recovery in transport experiments conducted without bentonite colloids. A meaningful K d value for Ce could not be calculated due to its precipitation as a Ce-carbonate colloids. Transport of both U(VI) and Cs was indifferent to the presence of bentonite colloids. However, the addition of bentonite in the injection solution effectively immobilized Ce, decreasing its recovery from 17-41% to 0.8–1.4%. This indicates that radionuclides which interact with clay colloids that undergo flocculation and deposition may effectively be immobilized in brackish aquifers. Lastly, the results of this study have implications for the prediction of potential mobility of radionuclides in safety assessments for future geological repositories to be located in fractured carbonate rocks in general and in brackish groundwater in particular.

54 ENVIRONMENTAL SCIENCES↗