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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Electron spin resonance of gamma-irradiated poly/ethylene 2,6-naphthalene dicarboxylate/.

The two types of radicals trapped in gamma-irradiated PEN 2,6 are identified by ESR as - O - CH - CH2 - O - (radical I) and a radical located on the naphthalene ring (radical II). The concentrations of the radicals in the gross polyer are 10 to 20% of I and 80 to 90% of II. Similar trapped radicals are established in beta-irradiated PET, a structurally related polymer.

Rogowski, R. S.↗
NASA NTRS1971

Electron spin resonance of gamma-irradiated poly/ethylene 2,6-naphthalene dicarboxylate/.

Study of the ESR spectra of this gamma-irradiated compound (PEN-2,6) aimed at determining the effect of replacing the phenylene ring with naphthalene rings in the polymer on the formation of radicals and at identifying the radical species. The two types of radicals trapped in the PEN-2,6 compound have been identified as -O-CH-CH2-O- (radical I) and a radical located on the naphthalene ring (radical II).

Rogowski, R. S.↗
NASA NTRS1981

Effect of gamma irradiation on the friction and wear of ultrahigh molecular weight polyethylene

The effect of sterilization gamma irradiation on the friction and wear properties of ultrahigh molecular weight polyethylene (UHMWPE) sliding against stainless steel 316L in dry air at 23 C is investigated, the results to be used in the development of artificial joints which are to surgically replace diseased human joints. A pin-on-disk sliding friction apparatus is used, a constant sliding speed in the range 0.061-0.27 m/s is maintained, a normal load of 1 kgf is applied with dead weight, and the irradiation dose levels are: 0, 2.5, and 5.0 Mrad. Wear and friction data and conditions for each of the ten tests are summarized, and include: (1) wear volume as a function of the sliding distance for the irradiation levels, (2) incremental wear rate, and (3) coefficient of friction as a function of the sliding distance. It is shown that (1) the friction and wear properties of UHMWPE are not significantly changed by the irradiation doses of 2.5 and 5.0 Mrad, (2) the irradiation increases the amount of insoluble gel as well as the amount of low molecular weight material, and (3) after run-in the wear rate is either steady or gradually decreases as a function of the sliding distance.

Jones, W. R.↗
DOE OSTI2024

Multiscale Modeling of Plutonium Radiation Chemistry in Nitric Acid Solutions. 1. Cobalt-60 Gamma Irradiation of Pu(IV)

We report careful manipulation of the plutonium oxidation states is essential in the study and utilization of its rich redox chemistry. To achieve this level of control, a comprehensive mechanistic understanding of radiation-induced plutonium redox chemistry is critical due to the unavoidable exposure of plutonium to ionizing radiation fields, both inherent and from in-process applications. To this end, we have developed an experimentally evaluated multiscale computer model for the prediction of gamma radiation-induced Pu(IV) redox chemistry in concentrated nitric acid solutions (1.0, 3.0, and 6.0 M). Under these acidic, aqueous solution conditions, cobalt-60 gamma irradiation afforded marginal net conversion of Pu(IV) to Pu(VI), the extent of which was dependent on the concentration of HNO 3 and absorbed gamma dose. Multiscale calculations, which are in excellent agreement with experimental data, indicate that this observation is due to a combination of inherent plutonium disproportionation reactions and several radiation-induced processes, including redox cycling between Pu(IV) and Pu(III), as achieved by the reduction of Pu(IV) by nitrous acid and hydrogen peroxide, the oxidation of Pu(III) by nitrate and hydroxyl radicals, and the sequential oxidation of Pu(IV) to Pu(V) and Pu(VI) by the remaining available yield of nitrate radicals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1975

Lymphoid cell kinetics under continuous low dose-rate gamma irradiation: A comparison study

A comparison study was conducted of the effects of continuous low dose-rate gamma irradiation on cell population kinetics of lymphoid tissue (white pulp) of the mouse spleen with findings as they relate to the mouse thymus. Experimental techniques employed included autoradiography and specific labeling with tritiated thymidine (TdR-(h-3)). The problem studied involved the mechanism of cell proliferation of lymphoid tissue of the mouse spleen and thymus under the stress of continuous irradiation at a dose rate of 10 roentgens (R) per day for 105 days (15 weeks). The aim was to determine whether or not a steady state or near-steady state of cell population could be established for this period of time, and what compensatory mechanisms of cell population were involved.

Foster, B. R.↗
NASA NTRS1972

Viruslike particles in the tissues of normal and gamma-irradiated Drosophila melanogaster.

A new finding of viruslike particles in the salivary and accessory glands, muscles, and nerves of normal and gamma-irradiated Drosophila melanogaster is discussed. In morphology and size, the particles seemed identical to those described in earlier reports. On the basis of the available results, it cannot be affirmed that these particles infect only dividing cells, since they are found in all the Drosophila tissues so far examined. Their relation to the aging process is felt to be an interesting subject for further study.

Miquel, J.↗
DOE OSTI2025

Radiation-Induced Chemical Yields of Carbon-Centered Radicals and Hydrogen Atoms from the Gamma Irradiation of n -Dodecane

Here, this study investigates the radiolytic yields of carbon-centered radicals and hydrogen atoms in n-dodecane under gamma irradiation. Utilizing molecular iodine (I 2 ) and 2,4,6-tri-tert-butylnitrosobenzene (3tBNB) as radical scavengers, we quantified the yields of molecular hydrogen and various carbon-centered radicals formed from bond scission of the solvent excited states. The yield of primary alkyl radicals was significantly lower than that of the secondary radicals, aligning with expected stabilities and bond dissociation energies. For the overall loss of n-dodecane, total yields of 0.598 ± 0.004 species/100 eV for C–C bond scission, 1.648 ± 0.012 species/100 eV for C–H bond scission, and 3.20 ± 0.10 species/100 eV for unimolecular H 2 elimination were determined. Notably, the I 2 scavenging data provided robust estimates, while the 3tBNB displayed lower efficiency in radical trapping. This research enhances our understanding of radiolytic processes in n-dodecane and offers insights for future studies on the behavior of hydrocarbons under ionizing radiation, with implications for improving UNF reprocessing strategies.

38 - RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCL↗
DOE OSTI2026

Financial Exposure After a Sealed-Source Release: Insurance Limits, Federal Cost Pathways, and Implications for Gamma Irradiator Substitution

This report assesses whether private insurance and existing federal authorities would likely provide meaningful financial protection to private operators of self-shielded gamma irradiators after a major sealed-source release. It does not answer this question quantitatively because publicly observable data on premiums, limits, uptake, and claims outcomes for this risk class appear sparse. Instead, it uses a qualitative structural analysis based on prior literature, review of relevant federal authorities, limited observable insurance-market evidence, expert outreach, and historical analogs. The analysis finds that available public and private mechanisms do not combine into a clear, dependable, or readily verifiable compensation structure for ordinary private sealed-source operators. Institutions therefore should not assume that either insurance or government response will make them financially whole after a severe incident. Source reduction and replacement remain more dependable than post-event financial mechanisms for reducing institutional exposure and broader radiological risk.

99 GENERAL AND MISCELLANEOUS↗
NASA NTRS1974

The effect of continuous low dose-rate gamma irradiation on cell population kinetics of lymphoid tissue

Cellular response and cell population kinetics were studied during lymphopoiesis in the thymus of the mouse under continuous gamma irradiation using autoradiographic techniques and specific labeling with tritiated thymidine. On the basis of tissue weights, it is concluded that the response of both the thymus and spleen to continuous low dose-rate irradiation is multiphasic. That is, alternating periods of steady state growth, followed by collapse, which in turn is followed by another period of homeostasis. Since there are two populations of lymphocytes - short lived and long-lived, it may be that different phases of steady state growth are mediated by different lymphocytes. The spleen is affected to a greater extent with shorter periods of steady-state growth than exhibited by the thymus.

Foster, B. R.↗