Yes, the Security Scan module will work in the background. In fact, the developers specify this on the homepage of Norton Security Scan:
"Runs in the background — won't interrupt your work or play." - Norton Security Scan page.
After installation, start a scan and then minimize it or send it to background and it will proceed doing its scanning operations. However, although they say it won't bother you while you work or play, it's possible to observe some performance issues. Norton is heavy on systems and consumes many resources.
Test it by installing the application through the download page: https://security.symantec.com/nss/getnss.aspx?langid=ie&venid=sym
