I want to use raspberry pi in space projects like cubesats. I worry about effects of space radiation on raspberry.Is this possible to do?or i need to choose another board or something like that?
The short answer is: it depends on how far up you plan to go, how long you plan to stay there, and when you do it. For most balloon-lifted flights, radiation probably isn't going to be a huge concern.
First, let me say that I have no experience or training with regards to radiation effects on electronics. However, there is a lot of useful information on the internet and here's what a quick search found. (I included my sources so you can read them for yourself and come to your own conclusions.)
It appears that the main concern for upper atmospheric radiation on electronics is from high-energy ration such as gamma and xrays.(1) The rest of the common radiation types found in the upper atmosphere either have little to no effect on electronics, or can be easily shielded with a piece of aluminum foil.(2) You would not have to worry much about gamma radiation below the ozone layer, which is typically around 12-19 miles (20-30 km) above sea level.(3) Brief pulses of gamma rays can be produced by thunderstorms, but there seems to be little actual data about the effects of this on electronics.(4) I also found an interesting document from NASA about ration effects on electronics (5), but it was difficult reading and seemed to suggest that solar storms (solar flares, etc.) were the main concern.
Conclusion: You shouldn't have to worry about radiation effects under the ozone layer of our atmosphere and you probably can't add enough shielding (beyond a bit of aluminum foil) to make the protection-vs.-weight worthwhile on a balloon-lifted project. Rocket-lifted projects have so many variables, I think it'd be nearly impossible to give any meaningful answer in this forum.
(1) https://hps.org/publicinformation/ate/q11162.html (2) http://www.clavius.org/envradintro.html (3) https://worldbuilding.stackexchange.com/questions/103721/can-a-radioactive-moon-affect-life-on-a-planet (4) https://en.wikipedia.org/wiki/Gamma_ray (5) https://nepp.nasa.gov/DocUploads/392333B0-7A48-4A04-A3A72B0B1DD73343/Rad_Effects_101_WebEx.pdf