IRRADIATIONIN TRIGA mk.2

REACTOR

Klemen Ambrožič

Review of a hypothetical ray irradiation chamber

Mentor: Dr. SNOJ Luka

OVERVIEW• Irradiation chamber goals.• Nuclear decay modes.• Nuclei activation by neutron radiation (n,).– Branching ratio.

• Neutron flux spectrum at the TRIGA mk. 2 reactor ports.• Application of reactor spectrum on nuclei activation and

decay.• Energy, released by emmision.• Calculation conclusion• TLD dosimeters• Plans for the future

Irradiation chamber goals• Heavy exposure:

• Medical equipment sterilization.• Plant seeds mutation.• ray exposure testing (satellites, particle accelerator

detectors).

• Minimal or none neutron exposure:• Causes discoloration in plastic and structural damage.

• Solution: Neutron activated source, moved from neutron field.

Nuclear decay modes• Decay law: – decay:

Heavy nuclei

– decay:

Neutron rich nuclei

Proton rich nuclei

– decaySpin change to base state, short decay times

• Activity: = Fig. 1: Table of isotopes and decays

decay

Fig. 2: decay scheme for after decay.

Nuclei activation by neutron radiation (n,)

• Reaction rate: : microscopic cross-section for absorption [barn=

Branching ratio can be given directly in or

: neutron flux []n: nuclei density []• ,

Nuclei activation by neutron radiation (n,)

for reaction on . Product:

Fig. 3: Absorption cross section for reaction on . Product: an . BR at low energies: 79%

Neutron flux spectrum in TRIGA mk.2irradiation ports

Fig. 4: Top view of TRIGA mk. 2 reactor scheme at IJS (Jeraj, Ravnik, 1999)

Neutron flux spectrum in TRIGA mk.2irradiation ports

Radial piercing thruport

𝜙 h𝑡 :𝐸<0,625𝑒𝑉 ,𝜙𝑒𝑝: 0,625eV <E<0,1MeV ,𝜙 𝑓 :E>0,1MeV

Neutron flux at core full power (250kW), core 189, MCNP calculated

Fig. 5: flux spectrum in Radial piercing thruport, normalised to the corresponding value at 1eV.

Neutron flux spectrum in TRIGA mk.2irradiation ports

Radial beam port

𝜙 h𝑡 :𝐸<0,625𝑒𝑉 ,𝜙𝑒𝑝: 0,625eV <E<0,1MeV ,𝜙 𝑓 :E>0,1MeV

Neutron flux at core full power (250kW), core 189, MCNP calculated

Fig. 6: flux spectrum in Radial beam port, normalised to the corresponding value at 1eV.

Application of reactor spectrum on nuclei activation and decay

• Equations:

• Solutions:– Neutron irradiation, :

– Decay , =:

• Meeting the goals: maximum and

Application of reactor spectrum on nuclei activation and decay

• Irradiation port candidate: Radial piercing thruport:– Not in contact with primary containment– Highest neutron flux

• Irradiation material candidate: :– Orders of magnitude larger at low E, than any other material– Short enough decay half time (54min) : relatively large ()– Large density ()

• Rule of thumb apriximations for calculations:– Neutron flux []– []

Application of reactor spectrum on nuclei activation and decay

• For nnmaxsaturation during irradiation

• Estimated uncertainties:

Due to aproximation and 10% due to uncerainties from nuclear data.

– Due to aproximation and 7% accuracy from power detemination

Calculation results

Fig. 6: Graph of , irradiation time: . Blue graph is calculated with given data, yellow and purple graph take into account uncertainties.

Graph of

Fig. 7: Log graph of , irradiation time: . Blue graph is calculated with given data, yellow and purple graph take into account uncertainties.

Calculation resultsLog graph of

Energy, released by emmision• Branching ratios• For each decay we

get in rays• Calculate specific

activity

Energy, released by emmision

Fig. 7: Graph of specific radiation power, irradiation time: . Blue graph is calculated with given data, yellow and purple graph take into account uncertainties.

Calculation conclusion• High flux density for particles.– Ideal for testing, sterilization

• Relativly short saturation times– Radiation times can be shorter to suite our needs

• Rule of thumb-> large uncertainties, but have general idea ( order of magnitude)

TLDs• Thermoluminescent dosimeters• Lithium fluoride, calcium fluoride• Gamma rays- material ionization• Free electrons captured in crystal

imperfections• Heat the crystal-> releasing trapped electrons• Released light counted using photomultiplier

Plans for the future• Smaller uncertainties (estimated 10%, under development)

– Exact calculation of and across all energies.– Exact consideration of and measurement

uncertainties.• MCNP simulations ( effect on flux density) (to do)

• FISPACT( dose rate simulation program) (to do)

• Large dose rate detector (TLD, scinilation detectors) (under development)

• Design plan, decommission plan, material acquisition (upper stages must be resolved first)

• Working aplication (upper stages must be resolved first)

Literature• Luka Snoj, Gašper Žerovnik, Andrej Trkov: Computational analysis of irradiation facilities at

the JSI TRIGA reactor• https://www-nds.iaea.org/exfor/endf.htm (14.11.2013)• http://www.inl.gov/gammaray/catalogs/pdf/gecat.pdf (14.11.2013)• http://www.oecd-nea.org/tools/abstract/detail/NEA-1564/ (14.11.2013) • http://www.ncnr.nist.gov/resources/n-lengths/ (14.11.2013) • http://

www.ndt-ed.org/EducationResources/CommunityCollege/RadiationSafety/radiation_safety_equipment/thermoluminescent.htm (19.11.2013)

• Frank Herbert Attix: Introduction to Radiological Physics and radiation dosimetry, Wiley-VCH Verlag GmbH& Co. KGaA, ISBN-13: 978-0-471-01146-0

• James J. Dudersradt, Louis J. Hamilton: Nuclear Reactor Analysis, Department Of Nuclear Engineering, The University Of Michigan, John Wiley & Sons, ISBN: 0-471-22363-8

• Ronald Allen Knief: Nuclear Engineering: Theory and Practice of Commercial Nuclear Power, Tylor & Francis, ISBN-13: 978-1560320890

• George I. Bell, Samuel Glasstone :Nuclear Reactor Theory, Van Nostrand Reinhold Inc.,U.S. (December 1970), ISBN-13: 978-0442206840