Doppler Coefficient Values: BOL & EOL in SI & Kelvin

[eulerpi]

I know that the typical values of Doppler coefficient over core life are about -1 *10^-5 Deltak/k/°F at BOL and -1.5 * 10^-5 Deltak/k/°F at EOL.

What are the value in SI units?

Are they the same, but in Kelvin?

Thanks,
Ken

 

[Morbius]

I know that the typical values of Doppler coefficient over core life are about -1 *10^-5 Deltak/k/°F at BOL and -1.5 * 10^-5 Deltak/k/°F at EOL.

What are the value in SI units?

Are they the same, but in Kelvin?

Thanks,
Ken

Ken,

Since a Celsius degree [ not degree Celsius - but Celsius degree -
the size of the interval ] is 9/5 a Fahrenheit degree - you can do the conversion.

Celsius degree = 9/5 Fahrenheit degree.

Divide by "Celsius degree":

1 = 9/5 Fahrenheit degree / Celsius degree = 1.8 F deg / C deg

Since this equals 1 - you can multiply any quantity by it without
changing the value.

If you take the BOL value of 1.0 * 10^-5 Delta k/k/F deg and multiply by
the above, and divide out the units that cancel - you get

1.8 * 10^-5 Delta k/ k / C deg = 1.8 * 10^-5 Delta k /k / Kelvin deg

the latter part is because the size of the Kelvin degree equals the size
of the Celsius degree.

Dr. Gregory Greenman
Physicist LLNL

 

[raining Pete]

Hi Ken,

The values given in the post are in units of Deltak/k/°F, which stands for change in reactivity per change in temperature per degree Fahrenheit. To convert to SI units, we can use the following conversions:

1 Deltak = 1e-2 k (from definition of Deltak)
1 °F = 5/9 K (from conversion formula)

Therefore, the values in SI units are:
-1 * 10^-5 Deltak/k/°F = -1 * 10^-5 * 1e-2 k / (5/9 K) = -1.8 * 10^-7 k/K at BOL
-1.5 * 10^-5 Deltak/k/°F = -1.5 * 10^-5 * 1e-2 k / (5/9 K) = -2.25 * 10^-7 k/K at EOL

And yes, these values are in Kelvin since that is the SI unit for temperature. Hope this helps!