Cf-252 FTC-CFZ-431 - Revision history

Burgjeff: /* Table of rates */

2017-01-25T20:07:10Z

Table of rates

2017-01-25T20:06:51Z

Table of rates

2017-01-25T20:06:40Z

Table of rates

2017-01-25T20:05:28Z

Formulas

2017-01-25T20:04:58Z

Formulas

2017-01-25T18:40:37Z

Initial source composition

2017-01-25T18:40:24Z

Initial source composition

2017-01-25T18:38:56Z

Overview

2017-01-25T18:34:13Z

Formulas

2017-01-25T18:33:04Z

Formulas

@@ Line 30: / Line 30: @@
 =Table of rates=
-Click [[Cf-252 rates table|here]] to open a table giving neutron/alpha rates of the source over for the following ten years.
+Click [[Cf-252 rates table|here]] to open a table giving neutron/alpha rates of the source for the next ten years.
 =Formulas=

@@ Line 30: / Line 30: @@
 =Table of rates=
-Click [[Cf-252 rates table|here]] to open a table giving neutron/alpha rates of the source over the next ten years.
+Click [[Cf-252 rates table|here]] to open a table giving neutron/alpha rates of the source over for the following ten years.
 =Formulas=

@@ Line 30: / Line 30: @@
 =Table of rates=
-Click [[Cf-252 rates table|here]] to open a table giving neutron rates and C-252 activity from dates 1/2017 to 12/2029. This calculation only includes neutrons from Cf-252, since all other daughter nuclei and possible impurities have a very low SF rate compared to Cf-252.
+Click [[Cf-252 rates table|here]] to open a table giving neutron/alpha rates of the source over the next ten years.
 =Formulas=

@@ Line 42: / Line 42: @@
 <math>n_{0}rate=(r_{252})(3.7)(0.5)^{\frac{\Delta t}{t252_{1/2}}}+(r_{250})(3.5)(0.5)^{\frac{\Delta t}{t250_{1/2}}}</math>
-where <math>r_{252}</math> and <math>r_{250}</math> are the initial SF rates of Cf252 and Cf250 ,respectively. 3.7 and 3.5 are the neutron multiplicities for Cf252 and Cf250, respectively.
+where <math>r_{252}</math> and <math>r_{250}</math> are the initial SF rates of Cf252 and Cf250, respectively. 3.7 and 3.5 are the neutron multiplicities for Cf252 and Cf250, respectively.
 =References=

@@ Line 38: / Line 38: @@
 The formula used for neutron rate [<math>s^{-1}</math>]:
-<math>k=(0.5)^{\frac{(year-1993)+\frac{month-3}{12}}{2.645}}</math>
+<math>\Delta t=\frac{(year-1993)+\frac{month-3}{12}}{2.645}</math>
-<math>n_{0}rate=9.835\times10^6\times k</math>
+<math>n_{0}rate=(r_{252})(3.7)(0.5)^{\frac{\Delta t}{t252_{1/2}}}+(r_{250})(3.5)(0.5)^{\frac{\Delta t}{t250_{1/2}}}</math>
-and for Cf-252 activity [<math>\mu Ci</math>]:
+where <math>r_{252}</math> and <math>r_{250}</math> are the initial SF rates of Cf252 and Cf250 ,respectively. 3.7 and 3.5 are the neutron multiplicities for Cf252 and Cf250, respectively.
 =References=

← Older revision		Revision as of 18:40, 25 January 2017
Line 6:		Line 6:

	=Initial source composition=		=Initial source composition=
−	~~CF252~~ used in the US is produced in batches at Oak Ridge National Laboratory which all have similar isotopic make up. I found the isotopic composition of a batch produced in 1991, two years before the production date of our source<ref> http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-12-22883 </ref>. Assuming our source has the same isotopic composition as the 1991 batch and a total mass of 4.2 <math>\mu</math>g, the values in the following table can be calculated. Cf250 is of particular important since as the source becomes aged it will contribute significantly to neutron rate.	+	Cf252 used in the US is produced in batches at Oak Ridge National Laboratory which all have similar isotopic make up. I found the isotopic composition of a batch produced in 1991, two years before the production date of our source<ref> http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-12-22883 </ref>. Assuming our source has the same isotopic composition as the 1991 batch and a total mass of 4.2 <math>\mu</math>g, the values in the following table can be calculated. Cf250 is of particular important since as the source becomes aged it will contribute significantly to neutron rate.

@@ Line 3: / Line 3: @@
 An official document for the CF-252 source with serial number FTC-CFZ-431 provides a value for the neutron rate and CF-252 mass as of 03/19/1993.
-The initial neutron rate and mass of cf-252 are stated to be <math>10^{7}s^{-1}</math> and 4.2<math>\mu g</math>, respectively.
+The initial neutron rate and mass of Cf-252 are stated to be <math>10^{7}s^{-1}</math> and 4.2<math>\mu g</math>, respectively. I am skeptical about the quoted neutron rate since 4.2 <math>\mu</math>g of pure Cf252 would not have a neutron rate that high. So, I did my calculations assuming that there was initially 4.2 <math>\mu</math>g of Cf with a isotopic composition that is typical for the date of production.
 =Initial source composition=
 CF252 used in the US is produced in batches at Oak Ridge National Laboratory which all have similar isotopic make up. I found the isotopic composition of a batch produced in 1991, two years before the production date of our source<ref> http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-12-22883 </ref>. Assuming our source has the same isotopic composition as the 1991 batch and a total mass of 4.2 <math>\mu</math>g, the values in the following table can be calculated.

@@ Line 35: / Line 35: @@
 =Formulas=
-As the Cf252 source ages neutron from Cf250 become significant since it has a half live of 13 years vs 2 for CF252. Aside from cf 252 and 240, there are no other significant neutron sources present.
+As the Cf252 source ages, neutrons from the SF of Cf250 become significant since it's has a half-life is 13 yrs, vs 2 yrs for CF252. Aside from Cf 252/250, there are no other significant neutron sources present.
 The formula used for neutron rate [<math>s^{-1}</math>]: