I doubt there are many IRIX or bru folks hitting this site, so I went searching. Found a man page for
bru and read through it.
To extract what is on the tape, you would use the -x option.
To inspect the archive on the tape (before extracting it) you would use the -i option. I would also suggest you use the -vv option with it to show info from the header block.
To step through this, try the following
$ bru -ivvf /dev/nrtape
This will check that your archive is good. It's possible that it isn't (from the information you already posted) - a tape that is almost 10 years old may not be in pristine condition.
From this point on I'm assuming the tape is okay...
Next, see what is on the tape - this is important if you don't want to overwrite information already on disk.
$ bru -tvf /dev/nrtape
This will list everything on the tape. If the output looks something like this...
./mydir/myfile
./mydir/myotherfile
then you can get ready to extract the archive into a newly created directory or any directory you want.
If the output looks something like this...
/mydir/myfile
/mydir/myotherfile
then the archive will possibly overwrite files on your system. You should know if you are willing to do that.
Once you verify the information, a generic extract could be done.
$ cd /where_I_want_extract
$ bru -xvf /dev/nrtape