Hello dear friends!
I'd like to propose to produce radioisotopes using the D-D reaction in miniature Tokamaks
, especially for medicine.
Tokamaks (including stellarators) top the rate of permanent nuclear fusion reactions for a given size and input powerhttps://en.wikipedia.org/wiki/Tokamakhttps://en.wikipedia.org/wiki/Stellarator
so big machines fed with D-T claim to produce net energy (present) at affordable cost (uncertain future)https://en.wikipedia.org/wiki/ITER
As a neutron source instead, the machines would
- Not try to produce any energy, even less net energy;
- Receive only deuterium (2H or D) without the scarce 50% tritium (3H or T);
- Be 10×10×10 times smaller than Iter with the same operating conditions:
Φ=1.2m and 50kW input and 20M€ (...err);
- Emit neutrons to irradiate fertile material like 98Mo.
Their activity or misuse would produce little plutonium, tritium and radioactive waste
. From my estimates, the isotopes production would be naturally good - maybe at a lower cost than the other alternatives to fission reactors.
---------- FiguresWelcome to double-checkers
, even more as usually, as a 3.7×1010
factor may well lack somewhere!
Iter is to produce 500MW heat (over 400s, let's forget that) from a 17.6MeV reaction, that's 1.8×1020
/s. At the same induction, density and 150MK, the D-D reaction is 0.012× as frequent as D-T and the machine is 1000× smaller, for a reaction rate of 2.1×1015
/s. Every second D+D reaction produces 3
He+n, the other T+p, but T is consumed 80× faster in a D+T reaction that produces one neutron too: 4
He+n. So 2.1×1015/s neutrons
The target shall catch all neutrons (how?) and consist of pure 98
Mo (that costs) in the example I choose. Something (Nitrogen behind graphite and molybdenum? Heavy methane?) shall thermalize the 4kW neutron flux to 77K=6.6meV:http://www.nndc.bnl.gov/sigma/index.jsp
(n, total) 6.07b http://www.nndc.bnl.gov/sigma/getPlot.jsp?evalid=15091&mf=3&mt=1&nsub=10
(n, elastic) 5.79b http://www.nndc.bnl.gov/sigma/getPlot.jsp?evalid=15091&mf=3&mt=2&nsub=10
(n, γ) 0.26b http://www.nndc.bnl.gov/sigma/getPlot.jsp?evalid=15091&mf=3&mt=102&nsub=10
I heavily overinterpretate curves made by models and don't integrate over the energy distribution. Then, the inelastic collisions section is 0.28b and (n, γ) make 90% of these or 1.9×1015/s
. Still 60% at 300K so money shall decide.
Over a 5×24h week, the tokamak produces 8.3×1020
atoms of 99
Mo. 2.75 days half-life = 343ks exponential decay mean 2.4×1015Bq = 65 000 Ci produced per week
Mo decays fully to 99m
Tc used for medical imaging. The worldwide demand is 12 000 Ci per week
according to Aieahttps://www.iaea.org/About/Policy/GC/GC54/GC54InfDocuments/English/gc54inf-3-att7_en.pdf
satisfied by one mini-tokamak - rather several ones, since 99
Mo must be transported swiftly. This allows for:
- Correction of limited errors in my estimate;
- Account for limited design constraints;
- A smaller machine, or if possible less strong fields;
- Production of other radioisotopes;
- Work during daytime.
Produce and sell two mini-tokamaks per continent for redundancy.
Marc Schaefer, aka Enthalpy