The U-238 decays by alpha emission generating Thorium 234. no decay used proton

you are right but in table of Nuclide , we see thet U 238 decay in several mode. alpha and beta(+ and -) and proton

U 235 also decay these. look the picture here http://reactorphysics.persiangig.com/image/InfoImager.aspx.gif

My friend, see http://www.nndc.bnl.gov/chart/chartNuc.jsp. in this site is possible to see many information for decai scheme. for uranium don't appear proton . I don't now any natural radionuclide when decay used proton.

Dataset #1:

Authors: F. E. CHUKREEV, V. E. MAKARENKO, M. J. MARTIN Citation:Nuclear Data Sheets 97,129 (2002)

Parent

Nucleus Parent

E(level) Parent

Jπ Parent

T1/2 Decay Mode GS-GS Q-value

(keV) Daughter

Nucleus Decay

Scheme ENSDF

file

238

92 U

2557.95 0+ 280 ns 6 IT: 97.4 4 %

238

92 U

Electrons:

Energy

(keV) Intensity

(%) Dose

( MeV/Bq-s )

Auger L 9.89 0.088 % 3 8.7E-6 3

Auger K 72.6 0.0067 % 9 4.8E-6 6

CE K 2442.4 20 0.22 % 0.0054

Gamma and X-ray radiation:

Energy

(keV) Intensity

(%) Dose

( MeV/Bq-s )

XR l 13.6 0.088 % 3 1.20E-5 5

XR kα2 94.654 0.0626 % 13 5.92E-5 13

XR kα1 98.434 0.1001 % 20 9.85E-5 20

XR kβ3 110.421 0.01254 % 24 1.38E-5 3

XR kβ1 111.298 0.0237 % 5 2.64E-5 5

XR kβ2 114.445 0.00921 % 18 1.054E-5 20

1879 32 % 8 0.60 16

2512.7 5 65 % 12 1.6 3

Gamma Coincidence Data:

For each gamma, the list of gammas in coincidence is given. If experimentally known, an estimate of the average time interval (in seconds) between both gammas is given

E(γ) Coincidence

44.915 635.18 (2.03E-10), 1879 (2.03E-10), 2512.7 (2.03E-10)

635.18 44.915 (2.03E-10), 1879

680.1 1879

1879 44.915 (2.03E-10), 635.18, 680.1

2512.7 44.915 (2.03E-10)

For uranium 235 the schem is: attachment

U-238 decay modes are alpha and, quite rarely, spontaneous fission (5e-5 %). The single beta-decay is forbidden because U-238 is a gg-nuclide. Double beta decay occurs with a probability of 2e-10%, so this is rather exotic.

U-238 decays decay chain is like this U-238---------alpha emission------->Th-234-----beta-emission----->Protactinium-234------Beta emission------>Uranium-234-----alpha emission--->Thorium-230----alpha----->Radium-226------alpha----->Radon-222-----alpha---->Polonium-218-------alpha----->Lead-214------beta----->Bismuth-214-----beta----->Polonium-214-----alpha---->Lead-210--------beta------>Bismuth-210-------beta----->Polonium-210------ Lead-206 (this is the stable nuclei)

There is not exist a nucleus in nature that be proton and neutron emitter. If we calculate the neutron and proton separation energy, this quantity is obtained positive. This positive quantity means that we must give an amount of energy to the all nuclei that founded in the nature to emit proton or neutron. Due to the Coulomb barrier. the proton separation energy is also greater than the neutron separation energy for a given nucleus. U-238 decays predominantly by alpha and can be undergoes spontaneous fission with a very small fission life time about 10^(-15) years.