The two fierce rivals go head-to-head in Cardiff on Saturday with the Welsh also looking to wrap up the Grand Slam, but Ireland still have all to play for.
Victory for the Irish would give them the chance of winning the Six Nations if England then slip up when they play Scotland later on Saturday evening.
However Moriarty says the determination is there in the Wales camp to wrap up their first clean sweep in the competition for seven years.
"Apart from winning a World Cup, it is the biggest thing for anyone in northern hemisphere rugby, so I would be really happy to achieve one," Moriarty said.
"We've been building nicely over 13 games (unbeaten), and against Ireland, we won't take a backward step to try and continue the streak.
"They are a good team, and we know what they are capable of."