Transmutation
Formal definition:
Nuclear reactions which change number and/or identity of nucleons in a nucleus
Notation:
X(a,b)Y
Projectile particle:
Target nucleus:
Exiting particle:
Transmuted nucleus:
a
X
b
Y
Example:
α + 60Ni
63
Ni + n
=
60
Ni(α, n)63Ni
Transmutation
Any type of particle may induce transmutation if energy is conserved:
Electrons, photons, protons, neutrons, nuclei, muons etc…
Q-value for X(a,b)Y:
Q = (ma + mX)c2 - (mb + mY)c2
Q < 0:
Reaction is endothermic, kinetic energy must be provided by the projectile.
Q > 0:
Ek(a) = 0 possible
Examples: Spontaneous fission, α-decay
First artificial transmutation
N2-gas
α-source
Magnet
Scintillator screen
L
Radium α-source, range of α ≈ 7 cm.
Scintillations seen when filling chamber
with nitrogen gas, for L up to 40 cm.
Rutherford et al 1917 - 1919:
α + 14N
17
O+p
Bending of radiation in magnetic field shows
that its charge equals unity and mass equals
1/4 of α-mass.
Q-value of reaction positive!
Pre-history of transmutation
1940
McMillian & Abelson: Discovery of Np-239
1941
Seaborg et al: Discovery of Pu-238 & Pu-239
1942
CP-1 critical
1946
Clementine critical: First fast reactor – mercury coolant
1951
EBR-I critical: First reactor to produce electricity – NaK coolant
1958
BR-5 critical: First reactor using sodium coolant
1959
27-VT critical: First reactor using lead-bismuth coolant
Early history of transmutation
1964
Steinberg et al (Brookhaven)
Irradiate Cs & Sr in high thermal neutron flux
Unrealistic, gain in terms of toxicity reduction questionable
1972
Claiborne (Oak Ridge)
Recycle transuranic elements in LWR:s or FBR:s
No analysis of Am recycling impact on core safety
1974
Foster et al (Los Alamos)
Recycle Am & Cm in fast neutron Accelerator Driven System
No detailed study performed
1989
Mukaiyama et al (JAERI)
Pu recycling in LWR:s & FBR:s, MA recycling in fast neutron ADS
Modern history of transmutation
1988
OMEGA program starts in Japan
Transmutation of Minor Actinides in fast reactors and ADS
1991
French law on Partitioning and Transmutation R&D program
P&T of MA is evaluated as waste management strategy
1993
Rubbia “proposes” ADS for energy production
A lot of attention directed to the field
2000
Start of 5th Framework Program in EU
Preconceptual design of ADS prototype (PbBi or He cooled)
2000
Federal funding to US “Roadmap” for ATW
Reprocessing no longer tabu in the US