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Nucengable
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Hello , If I wanted to design a radiation shield to protect from line source of Ca-252 with 5.3 Ci
what is the first thing I should think about..?
what is the first thing I should think about..?
Is that strictly Cf-252, or Cf-252 + Be.Nucengable said:Hello , If I wanted to design a radiation shield to protect from line source of Cf-252 with 5.3 Ci
what is the first thing I should think about..?
Hologram0110 said:You will likely want a two layered geometry. First you will want hydrogen rich materials to moderate the neutrons. This is usually water, oil, wax or plastics like polyethylene. You might also want to add something to it with a big absorption cross-section. This is usually boron. They sell borated polyethylene for this purpose. Depending on the budget you can even get enriched boron.
Whenever a neutron is absorbed you will generate a photon. So on top of the gammas from the source you will also have gammas being produced in the shielding. The energy depends on the isotope absorbing the neutron, I think hydrogen was around 2.1 MeV (but you should really check). So you need to make the outside layer a gamma shield. Which is anything with a high electron density. Lead is the most common material used but you can use pretty much anything depending on your application.
Firstly, the Cf-252 is going to be encapsulated in some sealed stainless steel tube. Noone would use bare Cf-252 as a neutron source.Nucengable said:its Cf-252 without Be
in my case I don't want to use it as neutron source , no transportation .. so the design geometry is not that important to me , the purpose of the design to have less than 10 microSv/hr at the surface of the shield.. the priority is be simple and to use the "right" shielding materials with the right thickness..
but what about Alpha emissions from Cf-252 ?
..
I though I can use these materials and in the same order
Hydrogenous medium
Gd-155 4 or maybe 5 mean free paths
2-3 mm Al or maybe lead
Hello , If I wanted to design a radiation shield to protect from line source of Ca-252 with 5.3Ci what is the first thing I should think about..?
Californium Industrial Loan Program:
The DOE inventory of sealed 252-Cf sources is stored at the Radiochemical Engineering Development Center of Oak Ridge National Laboratory (ORNL). Californium-252 is produced, purified, and encapsulated at ORNL as a byproduct of DOE’s heavy element program. While source material is sold to commercial vendors at a current price of $60/μg of 252-Cf, plus encapsulation, packaging, and transportation charges, government researchers and contractors can obtain DOE sources on loan without charge for the radioisotope.
If an appropriate source is available from the DOE source inventory at ORNL, the loanee pays only the technical service charges incurred for source preparation, shipment, and return. As part of the loan agreement, DOE requires source return to ORNL after use, eliminating source disposal concerns and costs to the user.
One microgram of 252-Cf emits 2.314 × 10^6 fast neutrons/s with a 2.645-year half-life. Typical costs for loan and return of a <7μg source total ~$11,000. (This fee is waived under the University Loan Program for university research and teaching applications.) Similar costs for a source in the range of 7μg to 3 mg (neutron intensities ranging up to 7 × 10^9/s ) total ~$20,000, while sources in the 3- to 5-mg range total ~$28,000. Loan/return costs of pre-existing sources from inventory containing >5 mg total ~$32,000. Sources containing >8 mg typically require custom fabrication, but a source containing the maximum permitted 252-Cf content of 50 mg (neutron intensity ~10^11/s) can be obtained for ~$51,000. None of these costs include transportation charges. Sources with neutron intensities <10^8/s can be obtained at lower cost from commercial vendors, but potential costs for end-of-use source disposal should be evaluated. Loan costs for high-intensity sources compare very favorably with procurement costs for electronic neutron generators and accelerators with comparable intensities. The choice of radioisotopic vs electronic neutron sources is dependent on the specific application and on a variety of practical factors.
I believe it is an exercise for a class project.cmb said:On a personal note, the first thing I'd say you should think about is why someone would consider giving you authority on that much nuclear material yet you still need to ask such a question.
I don't understand how you (Nuc.. and Ash..) might come across, or be responsible for, 5.3Ci of Cf-252 and need to ask these questions. I thought/imagined such quantities were under strict control from ORNL and you should not be getting your hands on such quantities unless you were VERY well briefed in the first place.
Could you enlighten us on the use, and provenance, of this Cf-252? Is that much Cf available to production lines these days for some production-based purpose?
Cf-252 has a specific activity of 19.85TBq/g. 5.3Ci is 0.196TBq, so that'd be 10mg of material (where did you get 0.29g from?). In any case, it is a shed-load of neutrons.
I suspect you are confused. In the UK I seem to recall there is some test/industrial sample limit for some classifications at 200kBq, which is 5.4μCi. Maybe there is a similar limit elsewhere. Is this what you have/will have, 5.4μCi?
Firstly I have a cylindrical 5.3 Ci (Cf-252) neutron source with (height= 1inch and diameter=1mm) which its about (0.29 g) and I guess its too huge to use as a neutron source but this was the deal. it emits an alpha particle 97% of the time and fissions spontaneously about 3% of the time emitting approximately 3.6 neutrons per fission
2.314E6n/ug times 2.9e5 ug equalsCf emits 2.314 x 10^6 neutrons per sec per μg
Astronuc said:I believe it is an exercise for a class project.
..cmb said:On a personal note, the first thing I'd say you should think about is why someone would consider giving you authority on that much nuclear material yet you still need to ask such a question.
I don't understand how you (Nuc.. and Ash..) might come across, or be responsible for, 5.3Ci of Cf-252 and need to ask these questions. I thought/imagined such quantities were under strict control from ORNL and you should not be getting your hands on such quantities unless you were VERY well briefed in the first place.
Could you enlighten us on the use, and provenance, of this Cf-252? Is that much Cf available to production lines these days for some production-based purpose?
Cf-252 has a specific activity of 19.85TBq/g. 5.3Ci is 0.196TBq, so that'd be 10mg of material (where did you get 0.29g from?). In any case, it is a shed-load of neutrons.
I suspect you are confused. In the UK I seem to recall there is some test/industrial sample limit for some classifications at 200kBq, which is 5.4μCi. Maybe there is a similar limit elsewhere. Is this what you have/will have, 5.4μCi?
Californium(Cf)-252 is a radioactive element that is commonly used in scientific research and industrial applications. It requires shielding design because it emits highly energetic radioactive particles, which can be harmful to humans and the environment if not properly contained.
When designing shielding for Californium(Cf)-252, factors such as the type and amount of radiation emitted, the distance from the source, the duration of exposure, and the intended use of the material being shielded should be taken into account.
Commonly used materials for shielding Californium(Cf)-252 include lead, concrete, steel, and water. These materials are dense and have the ability to attenuate the energetic particles emitted by the radioactive element.
The thickness of shielding needed for Californium(Cf)-252 can be determined by using mathematical calculations that take into account the properties of the shielding material and the type and energy of the radiation emitted by the element. It is recommended to consult a radiation safety expert for accurate calculations.
Yes, there are regulations and guidelines set by various organizations, such as the International Atomic Energy Agency (IAEA) and the Nuclear Regulatory Commission (NRC), for Californium(Cf)-252 shielding design. It is important to follow these regulations to ensure the safe use and handling of the radioactive material.