That's going to be quite a challenge, since Renwal has been out of business for a long time. And that kit has a lot of parts. I sure wouldn't want to tackle it without instructions.
The Renwall nuclear sub molds got modified several times before the company went out of business. I'm pretty sure the kit is currently in the catalog of Revell Germany. If all else fails, you might e-mail that company for help.
Good luck.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.