1. The problem statement, all variables and given/known data

Find the energy which comes out with fission of the nucleus of deuterium and tritium, so we receive like product the nucleus of helium.

mass of tritiumm(\stackrel{3}{1}H)=3,016049u
mass of the nucleus of deuterium m(\stackrel{2}{1}H)=2,013553u
mass of the nucleus of helium m(\stackrel{4}{2}He)=4,002603u


2. Relevant equations

\Delta E=\Delta m c^2

3. The attempt at a solution

The nuclear reaction

\stackrel{2}{1}H + \stackrel{3}{1}H \rightarrow \stackrel{4}{2}He + \stackrel{1}{0}n + energy

How will I find the mass of triton( the nucleus of tritium) ?

http://atom.kaeri.re.kr/ton/

Above link will give you information about all nuclides.

Ok, thanks I lot. As result I get:

(3,016049u+2,013553u)-(4,002603u+1,008665u)=0,018334

0,018334*931,494 MeV=17,078011 MeV

And in my text book results it is 17,8 MeV. Is their fault?

I don't know the correct value. If you did the calculation correctly, the text book looks like a typo - presumably they intended 17.08 MeV.