Possible options for spent nuclear fuel rods include

Option #1: they usually keep it buried in underground either near-surface disposal for short and intermediate-lived waste (buried a depth of 10 meters below sea level) or deep geological disposal for all kinds of waste (buried a depth of 250 to 1000 m)

Option #2: they usually submerged in a pool that has more than 20 ft deep of water and stored by racks and they cool it first before storing it and water is continuously circulated to draw heat.