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hello,everybody .Doppler coefficient will be positive?
Whether the Doppler coefficient (for resonance absorption) is positive or negative depends on the composition of the fuel/core.googlefans said:hello,everybody .Doppler coefficient will be positive?
Astronuc said:Whether the Doppler coefficient (for resonance absorption) is positive or negative depends on the composition of the fuel/core.
If resonance absorption leads to more (n,γ) and less fission then it has a negative effect on reactivity in a critical system.
If the absorption leads to more fission and less (n,γ), then it has a positive effect.
In an LWR (water moderated reactor) the Doppler coefficient is negative. The U-238 resonances absorb neutrons more readily, and to some extent, the resonance absorption of U-235 and Pu-239 resulting in (n,γ) compete with those resulting in fission.
Some fast and intermediate spectrum reactors may have a positive Doppler coefficient with certain configurations. Such configurations are to be avoided.
References:
http://www.barc.gov.in/publications/eb/golden/reactor/toc/chapter1/1_1.pdf
http://www.inl.gov/technicalpublications/Documents/4502642.pdf
The Doppler coefficient, also known as the Doppler factor, is a value used in physics to describe the change in frequency or wavelength of a wave due to the relative motion between the source of the wave and the observer.
The Doppler coefficient is calculated using the formula: fo = fs(c±v)/c, where fo is the observed frequency, fs is the source frequency, c is the speed of the wave, and v is the relative velocity between the source and the observer.
The Doppler coefficient is significant because it allows us to understand and predict the effects of relative motion on waves, such as sound and light. It is also used in various applications, such as radar and astronomy, to measure the speed and direction of objects.
Yes, the Doppler coefficient can be negative. This occurs when the source and the observer are moving towards each other, resulting in a decrease in observed frequency. In this case, the negative value indicates a decrease in frequency, while a positive value indicates an increase in frequency.
The Doppler coefficient affects the perceived pitch of a sound by changing the frequency at which the sound is heard. For example, if a sound source is moving towards an observer, the perceived pitch will be higher due to an increase in frequency. Similarly, if the source is moving away, the perceived pitch will be lower due to a decrease in frequency.