Photon buildup in shielding

In summary, the conversation discusses the use of different approximations and tables for photon buildup in shielding, including the Berger approximation and the Geometric Progression Approximation. It is recommended to consult with multiple sources and do thorough research to ensure the accuracy and reliability of the information being used.
  • #1
GammaScanner
10
0
Who do you believe?

I'm doing some shielding calcs for Cs-137 (662 KeV gamma) in stainless steel (Fe seems close enough) with ux (mfp) in the range of 5 to 15.

Shultis and Faw in Radiation Shielding (2000) treat Photon buildup pretty well.

Their coefficients for the Berger approximation agree pretty well with the tables in Martin's Physics for Radiation Protection. (2006) A lot better than the single and double term Taylor forms.

But Shultis and Faw say the Berger may be off by up to 45%. Glasstone and Sesonske (4th ed) say the Berger is more accurate than the Taylor.

Shultis and Faw say the Geometric Progression approximation is the cat's meow, but they don't treat it well enough for me to get a handle on it.

Is there a generally accepted table of buildup factors, or formula and coefficients, for photon buildup in shielding that most people use or accept as standard?

Is there a good description of the Geometric Progression Approximation available on the web somewhere?

For now I'm using the Berger approximation.

Thanks!
 
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  • #2
A lot of health physicists use tables from the Handbook of Health Physics and radiological Health edited by Shlein as a rough approximation, and then add an additional HVL or TVL (depending on what they're shielding) just to be sure. With a mfp between 5 and 15, the tables give a relatively lrge range of buidlup factor. For example, 5 mfp gives a buildup between 6.74 and 7.68. For 15 mfp, the factor is 27.5 to 35.1.
 
  • #3
It's difficult to say who to believe without knowing more about the sources and their credibility. It's always a good idea to do some research and compare multiple sources before making a decision. In this case, it seems like Shultis and Faw have done a thorough analysis and have provided reliable information, but it's always good to check with other sources as well. As for the Geometric Progression Approximation, it's always best to consult with experts in the field or refer to peer-reviewed studies for accurate information. Ultimately, the most important thing is to make sure the information you're using is trustworthy and reliable.
 

1. What is photon buildup in shielding?

Photon buildup in shielding is the accumulation of photons, or particles of light, in a material used to block radiation. This buildup can occur over time as photons continually interact with the shielding material, leading to an increase in radiation levels.

2. Why is photon buildup a concern in shielding?

Photon buildup in shielding can be a concern because it can lead to an increase in radiation exposure for individuals working with or near the shielding material. This can be particularly problematic in high-radiation environments, such as nuclear power plants or medical facilities.

3. How is photon buildup measured?

Photon buildup is typically measured using dosimeters, which are devices that can detect and measure the amount of radiation in a given area. These measurements can help determine the effectiveness of shielding and any potential need for maintenance or replacement.

4. What factors contribute to photon buildup in shielding?

Several factors can contribute to photon buildup in shielding, including the type and thickness of the shielding material, the type and energy of the radiation being blocked, and the length of time the shielding has been in place. Environmental factors, such as temperature and humidity, can also play a role.

5. How can photon buildup in shielding be prevented?

To prevent photon buildup in shielding, it is important to regularly monitor radiation levels and replace shielding materials as needed. Using thicker or more effective shielding materials, implementing proper maintenance and cleaning procedures, and controlling environmental factors can also help prevent photon buildup. Additionally, following safety protocols and limiting exposure to radiation can minimize the risk of photon buildup.

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