Soviet nuclear test nº30, thermonuclear bomb test with a fizzled secondary (1956)

Presumably, the scenes shown are all the test nº30, as has been suggested in old forum and video discussions (now lost). This info is not mentioned in any of the sources of the videos though. Personally, I think this could be another test. Read comment below.

After the successful test of the first two-stage thermonuclear bomb by the USSR, the RDS-37 in 1955, efforts were directed into developing a nuclear warhead for the R-7 ICBM with this new technology. Modernized versions of the RDS-37 were tested on 1956 (four or five, see "ref" at the end. See also https://www.youtube.com/watch?v=osZ2dDxDajs). The first of these tests was successful; a 900 kt explosion occurred, out of 600-700 kt expected (yield of the charges to be tested at Semipalatinsk were reduced after the incidents with the RDS-37 test of 1955). Then, on September 2, another variant of the RDS-37 was tested, a bomb dropped from a Tu-16 and detonated at 1050 m. This time the secondary unit failed to ignite, yielding only 51 kt (out of 600-700 kt expected). This was the test nº30 in the official lists (codenamed Joe-25 in the US).

Scene 1 was from a video uploaded in the youtube channel https://www.youtube.com/@UCocSPp2haPIl0_edFrDimPw, that is no longer available. Scenes 2 and 3 are from the film https://www.youtube.com/watch?v=cTMCxFa1y9E (shown with little context), and the fourth is from the film https://youtu.be/ybwbuUvlgvY?t=1140 (shown in the context of nuclear testing with Luna/Mars rockets, 1961-1962).
About the identification:

I'm wary to accept that this explosion was indeed the test nº30 (as this is not stated in any source known by me and the other people who discussed around this years ago; as occur with many other soviet nuclear tests images, are nuke nerds like us who suggest the identities. The id of this explosion was first pointed out by the youtuber @RadiationHazard ).

On the one hand, scenes of this explosion appear frequently together with other tests of 1956, so it is likely that all these scenes came from a single soviet documentary about the 1956 nuclear testing program. In one of the modern documentaries where these scenes were used (Свидание с бомбой (2005), link below), the scene of the explosion is preceded by an airdrop of a RDS-37-like bomb. Also, if one compares the fireball's radius-vs-altitude aspect of an explosion of similar parameters than the test nº30, like the US test Dominic Muskegon, the fireballs match strikingly well (see image link at the end) (this is, though, not a solid criteria in any way because fireball size varies non-linearly with yield, and apparent ground horizon can be deceptive considering camera altitude, angle, and terrain features).

On the other hand, it seems very unlikely to me that, due to the secrecy of the Soviet nuclear testing program, a failed nuclear test would be portrayed so often. Consider also that the scenes in soviet films about nuclear testing often are put together only for visual effects but are unrelated (about this, a casing designed for certain charge can be used to carry another. For example, it is mentioned that test nº28 was assembled as a full two-stage device but with the secondary removed. See also https://www.youtube.com/watch?v=7BagGBBS3FQ , a video showing testings from 1961 with the drop sequence of a similar bomb in the context of "low yield" explosions). Also, the way the camera moves following the explosion rising in the last scene makes me think a small explosion (not a 600-900 kt explosion) was expected. And there is also the fact that the scenes of this explosion are very frequently put together with scenes related to military exercises, like the film Ядерное оружие в готовности к применению.

To add to this confusion, the first scene I show in this video was on a tv docu that showed it together with scenes of Totskoye and test nº31, so maybe those came from a single soviet film about military exercises with nuclear weapons. There is a explanation for this last point though. Literature says that the servicemen who participated in the military exercises of 1956 (test nº31) assisted to a series of nuclear tests conducted before that, including the test of a 900 kt explosion (test nº29). So it is reasonable they assisted to the test nº30 too, and that is why this explosion is often associated with the military exercises of 1956.
(Ref) Very interesting information/discussion about the testing program of thermonuclear charges of 1956:
https://pfc-joker.livejournal.com
/66030.html?noscroll#comments

Comparison between this explosion fireball and the one of Dominic Muskegon (50 kt, 913 m):
https://postimg.cc/N9f0RFWN
#nuclearweapons #sovietunion #ussr #coldwar #history #ядерноеоружие #СССР #история

Видео Soviet nuclear test nº30, thermonuclear bomb test with a fizzled secondary (1956) канала synthetic sunset