There is scanning, but basically you use a radar-like blip while flying within a system. If a planet/area has something of interest it will show up with a red indicator. The actual scanning is like ME2, but there is only 1 spot on a planet to be probed. While you have unlimited radar blips, and probes, each time you use a blip the Reapers hone in on you, and after 2 or 3 blips will come chase you within that particular system. You can escape by flying to another system, or using a Relay to go elsewhere. The system will be clear of Reapers (And therefore safely scan-able) after completing a mission or side quest.