| 摘要 |
<p>925,186. Nuclear fuel elements. UNITED STATES ATOMIC ENERGY COMMISSION. Dec. 21, 1960 [March 7, 1960], No. 43895/60. Class 39 (4). A nuclear fuel element is prepared by compacting a powdered ceramic nuclear fuel within a metal container by vibrating the container at its resonant frequency and varying the frequency of vibration to follow the resonant frequency change caused by compaction of the powder. As an example of the preferred mode of carrying out the invention, a weighed amount of crushed and screened uranium dioxide is poured into a Zircalloy-2 tube to which a lower end cap has been welded and the tube vibrated at 1000 c/s. on a moving coil vibrator at low power. The frequency is rapidly reduced until the resonant frequency of the tube at about 180 c/s. is reached whereupon rapid densification occurs and full power is turned on, the frequency being swept slowly back and forth across the resonant frequency several times (Œ100 c/s.), the resonant frequency changing to about 240 c/s. as the particles densify. The frequency is then lowered to about 100 c/s. and then again raised to the resonant frequency and swept across it several times. This is followed by a raising of the frequency until a harmonic of the fundamental resonant frequency is reached which is also swept across several times, the frequency finally being raised to 4000 c/s. The entire procedure takes about three minutes. Either automatic or manual frequency changing may be used. Specification 841,608 is referred to.</p> |
