Throughout the 1960s, AFWL scientists built facilities to simulate nuclear effects such as transient radiation, x-rays and electromagnetic pulse. For example, in 1965, AFWL's Civil Engineering Research Branch began studies using conventional high explosives to simulate a nuclear blast to test the hardness or survivability of underground missile silos and command centers. The Weapons Laboratory built facilities during the 1960s to simulate nuclear effects such as transient radiation, x-rays and electromagnetic pulse. To study the latter, the ATLAS-I (better known as TRESTLE), the largest simulation facility ever built, was completed on the east side of Kirtland AFB during the late 1970s.