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The mushroom cloud created by Orel-1 in 1956
Country Narozalica
Test seriesOrel
Test siteYandar Valley, Narozalica
DateJune 16, 1956
(64 years ago)
Test typeAtmospheric
Device typePlutonium-pit implosion fission reaction
Yield25 Kt (approx. 105 TJ)
Test chronology
Orel-2 →

Orel-1 or Orel I (Narodyn: Орел-1; Orel-1) was the first in a series of nuclear weapons tests conducted by Narozalica on the northern portion of the Yandar Valley between 1956 and 1957 and was the first successful nuclear test carried out by the Narozalic Armed Forces. It was detonated at 6:17 a.m. on June 16, 1956 by the Narozalic Army on a damp permafrosted plain in the valley, the site of many of the Orel tests. There were no buildings nearby that were damaged by the explosion but the failure to account for wind speed and direction caused radioactive fallout to spread across Narozalica. The radioactive consequences of the explosion led to Narozalica lobbying the states in possession of nuclear weapons on the restricting of nuclear testing to strictly underground tests only in 1960, and led to the signing of the Nuclear Testing Accords in Patovatra in 1961, outlawing atmospheric, exoatmospheric and underwater nuclear tests between its signatories.

The code-name for the detonation, Orel, is Narodyn for "eagle" and was suggested by influential Narozalic fission experimenter and scientist Sergei Semenov in 1955 and was adopted in the same year for his outstanding contributions to the project. The test was an implosion-based plutonium fission device, a design that would remain unchanged until Orel-6 in 1968. The design's complexity led to divisions with the Narozalic government and armed forces as to whether funding for the test should continue and whether or not it would work. President Vladislav Pudovkin and his successor Mikhail Petrenko both chose to continue the project throughout the 1950s, although it required significant contributions from scientific test facilities and laboratories from the mainland.

A steel containment vessel was created to house Orel-1 before it was tested to contain the plutonium for re-use should a fizzle occur, and unlike its counterparts, the containment vessel was used when the bomb was detonated. No rehearsal for the test occurred and bomb was cleared for detonation at 5:57 a.m. on June 16, releasing an explosive yield of 25 kilotonnes of TNT, the largest test in history at the time. A number of scientists and nuclear experimenters from throughout Euclea observed the explosion. The crater caused by the explosion now serves as a historic landmark in the Yandar Valley that is regularly visited by tourists.