U-234 is fertile but non-fissile. It is not capable of undergoing fission with low-energy neutrons, but decays into elements that are fissile.

is an infertile isotope with a half-life of...



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Note added at 35 mins (2008-06-05 05:10:49 GMT)
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I'm thinking non-fertile or even non-reproductive might work better but I'm not getting many google hits on any of these except a few for non-fertile. Unless there is a more specific scientific term, I think this would work.

Fertile materials that occur naturally which can be converted into a fissile material by irradiation in a reactor include: # uranium-234 which converts into uranium-235

It means that isotope U-234 cannot be used to breed fissile isotopes by neutron bombardment of the nucleus of U-234.

http://www.springerlink.com/content/x5281kp07w8767x1/
effective source value: the total coefficient of isotope breeding, the number of fissions,. and the energy multiplication coefficient. ...
http://arxiv.org/ftp/physics/papers/0608/0608011.pdf
Breeding of fissile material in the multi-MW target. http://nes.web.psi.ch/abstracts/abstract104.html
neutron production or isotope breeding. ..
http://www.freepatentsonline.com/4370298.html
By far the most important isotope breeding reaction of this embodiment is the following series of nuclear transformations
http://www.chem.au.dk/~db/fusion/ICCF4
when a mature technology, will be able to help the proliferation of nuclear materials; can it, e.g., be used for fissile isotope breeding? ...
http://weblog.xanga.com/bartoncii/605516985/kloosterman-on-m...
The remainder is the non-fissile isotopes U-234 and U-238
http://www.brucepower.com/uc/GetDocument.aspx?docid=2425
This leaves just enough neutrons to breed new fissile material. ... which would produce the non-fissile U-234, part of it can easily be stored in a hold-up ...