Reentry thermal testing of a general purpose heat source fueled clad

Peterson, D.E.; Frantz, C.E.

doi:10.2172/5359941

Cited by 2 publications

(3 citation statements)

References 2 publications

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“…The experimental details and helium release studies conducted during these heat treatments have been reported by Peterson and Frantz. 2 The general features of the apparatus used to obtain the helium release measurements have been described in detail by Early and Abernathey.' Each plutcnia sample was placed in a tantalum or tungsten cup and the system evacuated.…”

Section: Smentioning

confidence: 99%

Helium release from radioisotope heat sources

Peterson¹,

Early²,

Starzynski³

et al. 1984

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Diffusion of helium in 238 PuO 2 fuel was characterized s?. s a function of the heating rate and the fuel microstructure. The samples were thennally ramped in an induction furnace and the helium release rates measured with an automated mass spectro neter. The diffusion constants and activation energies were obtained from the data using a simple diffusion model. The release rates of helium were correlated with the fuel microstructure by metaJlographic examination of fuel samples. The release mechanism consists of four regimes, which are dependent upon the temperature. Initially, the release ss controlled by move nent of point defects combined with trapping along grain boundaries. This regime is followed by a process dominated by formation and growth of helium bubbles piong grain boundaries. The third regime involves volume diffusion controlled by movement of oxygen vacancies. Finally, the release at the highest temperatures follows the diffusion rate of intragranislar bubbles. The tendency for helium to be trapped within the grain boundaries diminishes with small grain sizes, slow thermal pulses, and older fuel. Activation energies and diffusion constants were correlated with previous measurements conducted on inert gases diffusing in ceramics. The helium release measured from a LightWeight Radioisotopic Heater Unit in an earlier study was verified, and the release behavior was predicted for a heat source containing the current fuel form.

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Section: Smentioning

confidence: 99%

Helium release from radioisotope heat sources

Peterson¹,

Early²,

Starzynski³

et al. 1984

Self Cite

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show abstract

“…The helium release rates measured in this study were analyzed based on Fick's laws of simple diffusion, an approach previously discussed by Peterson and Frantz. 2 Using the fractional release, F, as a function of time, we calculated an effective diffusion constant, D' (= D/a 2 , where a is the effective radius of the releasing unit). Variations in D' with temperature and therefore time, t, are accounted for by using the parameter, t, defined as = jo'D'dt…”

Section: Theorymentioning

confidence: 99%

“…Asvjtriing that Fick's laws of diffusion apply, one can derive the expression •nVtj (2) from which a value of T may tns<!etermined at a time, t : from a corresponding F value. Thus'a c *ime curve is helium was flowed into the furnace through the flowmeter over a range of 9 to 24 cc(STP)/min.…”

Section: (')mentioning

confidence: 99%