Atomicorp

libyaml and other packages are not provided by RHEL6. Here's all packages that are either missing in the Atomic+RHEL6 repositories, or are newer in EPEL than in Atomic:

PyYAML x86_64 3.10-3.el6 epel 157 k
libmicrohttpd x86_64 0.9.22-1.el6 epel 49 k
libyaml x86_64 0.1.3-1.el6 epel 52 k
ncrack x86_64 0.4-0.1.ALPHA.el6 epel 552 k
pyPdf noarch 1.12-4.el6 epel 63 k
pysvn x86_64 1.7.6-1.el6 epel 296 k
python-BeautifulSoup noarch 1:3.0.8.1-1.el6 epel 43 k
python-httplib2 noarch 0.7.7-1.el6 epel 70 k
python-nltk noarch 1:2.0.4-2.el6.1 epel 1.7 M
socat x86_64 1.7.2.2-1.el6 epel 245 k

So several of these are not compatible with openvas (libmicrohttpd for example, as well as pyaml). I highly recommend not using epel when you're using openvas, things can get unpredictable very quickly.