CATALOG OF WORLDWIDE NUCLEAR TESTING

 

V.N. Mikhailov

Editor-in-Chief

 

LA. Andryushin, N.P. Voloshin, R.I. Ilkaev, A.M. Matushchenko, L.D. Ryabev, V.G. Strukov, A.K. Chernyshev, and Yu.A. Yudin

Authors

 

begell-atom, llc

 

3. NUCLEAR TESTS AND PEACEFUL NUCLEAR EXPLOSIONS (1960-1962)

No.
Nation
Name
Date
Location
Type
Purpose
Method
Height/ Depth, m
Yield, kt
Comment
1960
301
France
Gerboise Bleue
02/13/60
Reggane , Algeria
SGE
WE
Tower
105
20-150
First French nuclear test
302
France
Gerboise Blanche
04/01/60
Reggane , Algeria
SGE
WR
Surface
<20
303
France
Gerboise Rouge
12/27/60
Reggane , Algeria
SGE
WE
Tower
100
<20
1961
304
France
Gerboise Verte
04/25/61
Reggane , Algeria
SGE
Unknown
Tower
< 1
Last French atmospheric nuclear test in Algeria
305
USSR
09/01/61
STS
AE
WR
Airdrop
660
16
306
USSR
09/04/61
STS
AE
WR
Airdrop
725
9
307
USSR
09/05/61
STS
AE
WR
Airdrop
710
16
308
USSR
09/06/61
STS
AE
WR
Airdrop
685
1.1
309
USSR
Groza
09/06/61
MTR
AE
WE
Rocket
22700
11
310
USSR
09/09/61
STS
SGE
SE
Surface
0.38
311
USSR
09/10/61
NZTS
AE
WR
Airdrop
2000
2700
312
USSR
09/10/61
NZTS
AE
WR
Rocket
390
12
313
USSR
09/10/61
STS
AE
WR
Rocket
170
0.88
314
USSR
09/11/61
STS
AE
WR
Airdrop
690
0.21
315
USSR
09/12/61
NZTS
AE
WR
Rocket
1220
1170
316
USSR
09/13/61
NZTS
AE
WR
Rocket
250
6
317
USSR
09/13/61
STS
AE
WR
Airdrop
710
0.001-20
318
USSR
09/14/61
STS
SGE
WR
Surface
0.4
319
USSR
09/14/61
NZTS
AE
WR
Airdrop
1740
1200
320
U.S.
Antler
09/15/61
NTS
UGE
WR
Tunnel
-402
2.6
321
U.S.
Shrew
09/16/61
NTS
UGE
WR
Shaft
-98
<20
322
USSR
09/16/61
NZTS
AE
WR
Rocket
1320
830
323
USSR
09/17/61
STS
AE
WR
Airdrop
695
20-150
324
USSR
09/18/61
NZTS
AE
WR
Airdrop
1500
1000
325
USSR
09/18/61
STS
SGE
SE
Surface
0.005
326
USSR
09/18/61
STS
AE
WR
Rocket
0.75
327
USSR
09/19/61
STS
SGE
SE
Surface
0.025
328
USSR
09/20/61
STS
AE
WR
Rocket
270
4.8
329
USSR
09/20/61
NZTS
AE
WR
Airdrop
1570
150-1500
330
USSR
09/21/61
STS
AE
WR
Rocket
110
0.8
331
USSR
09/22/61
NZTS
AE
WR
Airdrop
1320
260
332
USSR
09/26/61
STS
AE
WR
Airdrop
665
1.2
333
U.S.
Boomer
10/01/61
NTS
UGE
WR
Shaft
-100
<20
334
USSR
10/01/61
STS
AE
WR
Airdrop
700
3.2
335
USSR
10/02/61
NZTS
AE
WR
Airdrop
1500
250
336
USSR
10/04/61
STS
AE
WR
Airdrop
605
10.8
337
USSR
10/04/61
NZTS
AE
WR
Airdrop
2100
1500-10000
338
USSR
10/06/61
NZTS
AE
WR
Airdrop
2500
3900
339
USSR
Grom
10/06/61
MTR
AE
WE
Rocket
41300
40
340
USSR
10/08/61
NZTS
AE
WR
Rocket
1500
15
341
U.S.
Chena
10/10/61
NTS
UGE
WR
Tunnel
-255
<20
342
USSR
10/11/61
STS
UGE
FMS
Tunnel V-1
1
First Soviet underground (tunnel) nuclear explosion
343
USSR
10/12/61
STS
AE
WR
Airdrop
670
15.2
344
USSR
10/17/61
STS
AE
WR
Airdrop
505
6.6
345
USSR
10/19/61
STS
AE
WR
Airdrop
710
0.001-20
346
USSR
10/20/61
NZTS
AE
WR
Rocket
1000
1450
347
USSR
10/23/61
NZTS
UWE
WE
Torpedo
4.8
348
USSR
10/23/61
NZTS
AE
WR
Airdrop
3500
12500
349
USSR
10/25/61
NZTS
AE
WR
Airdrop
1500
300
350
USSR
10/25/61
STS
AE
FMS
Airdrop
500
0.4
351
USSR
10/27/61
NZTS
SWE
WE
Torpedo
16
352
USSR
K-1
10/27/61
MTR
SPE
WE
Rocket
150000
1.2
First Soviet space nuclear explosion
353
USSR
K-2
10/27/61
MTR
SPE
WE
Rocket
300000
1.2
354
U.S.
Mink
10/29/61
NTS
UGE
WR
Shaft
-192
<20
355
USSR
10/30/61
STS
AE
WR
Airdrop
470
0.09
356
USSR
10/30/61
NZTS
AE
WR
Airdrop
4000
50000
Largest Soviet nuclear explosion
357
USSR
10/31/61
NZTS
AE
WR
Airdrop
2280
5000
358
USSR
10/31/61
NZTS
AE
WR
Airdrop
1530
150-1500
359
USSR
11/01/61
STS
AE
WR
Airdrop
475
2.7
360
USSR
11/02/61
NZTS
AE
WR
Airdrop
1400
120
361
USSR
11/02/61
NZTS
AE
WR
Airdrop
1500
280
362
USSR
11/02/61
STS
AE
WR
Airdrop
645
0.6
363
USSR
11/03/61
STS
SGE
SE
Surface
< 0.001
364
USSR
11/03/61
STS
AE
WR
Airdrop
635
0.9
365
USSR
11/04/61
NZTS
AE
WR
Airdrop
1770
15
366
USSR
11/04/61
NZTS
AE
WR
Airdrop
1750
150-1500
367
USSR
11/04/61
NZTS
AE
WR
Airdrop
2240
6.2
368
USSR
11/04/61
STS
SGE
WR
Surface
0.2
369
France
Agathe
11/07/61
Hoggar, Algeria
UGE
WR
Tunnel
<20
First French underground (tunnel) nuclear explosion
370
U.S.
Fisher
12/03/61
NTS
UGE
WR
Shaft
-366
13.4
371
U.S.
Gnome
12/10/61
New Mexico
UGE
IPE
Shaft
-360
3
Program Plowshare. Multiple-purpose experiment in salt
372
U.S.
Mad
12/13/61
NTS
UGE
WR
Shaft
-181
0.5
373
U.S.
Ringtail
12/17/61
NTS
UGE
WR
Shaft
-366
<20
374
U.S.
Feather
12/22/61
NTS
UGE
WR
Tunnel
-247
0.15
1962
375
U.S.
Stoat
01/09/62
NTS
UGE
WR
Shaft
-305
5.1
376
U.S.
Agouti
01/18/62
NTS
UGE
WR
Shaft
-261
6.4
377
U.S.
Dormouse
01/30/62
NTS
UGE
WR
Shaft
-363
<20
378
USSR
02/02/62
STS
UGE
WE
Tunnel A-1
0.001-20
First Soviet underground nuclear explosion for weapons effects
379
U.S.
Stillwater
02/08/62
NTS
UGE
WR
Shaft
-181
3.07
380
U.S.
Armadillo
02/09/62
NTS
UGE
WR
Shaft
-240
7.1
381
U.S.
Hard Hat
02/15/62
NTS
UGE
WE
Shaft
-290
5.7
DoD test
382
U.S.
Chinchilla
02/19/62
NTS
UGE
WR
Shaft
-150
1.9
383
U.S.
Codsaw
02/19/62
NTS
UGE
WR
Shaft
-212
<20
384
U.S.
Cimarron
02/23/62
NTS
UGE
WR
Shaft
-305
11.9
385
U.S.
Platypus
02/24/62
NTS
UGE
WR
Shaft
-58
<20
386
UK
Pampas
03/01/62
NTS
UGE
WR
Shaft
-366
9.5
First UK underground (shaft) nuclear explosion
387
U.S.
Danny Boy
03/05/62
NTS
UGE
WE
Crater
-33.5
0.43
Crater in basalt. DoD test
388
U.S.
Ermine
03/06/62
NTS
UGE
SE
Shaft
-73
<20
389
U.S.
Brazos
03/08/62
NTS
UGE
WR
Shaft
-256
8.4
390
U.S.
Hognose
03/15/62
NTS
UGE
WR
Shaft
-244
<20
391
U.S.
Hoosic
03/28/62
NTS
UGE
WR
Shaft
-187
3.4
392
U.S.
Chinchilla II
03/31/62
NTS
UGE
WR
Shaft
-140
<20
393
U.S.
Dormouse Prime
04/05/62
NTS
UGE
WR
Shaft
-261
10.6
394
U.S.
Passaic
04/06/62
NTS
UGE
WR
Shaft
-233
<20
395
U.S.
Hudson
04/12/62
NTS
UGE
WR
Tunnel
-146
<20
396
U.S.
Platte
04/14/62
NTS
UGE
WR
Tunnel
-171
1.85
397
U.S.
Dead
04/21/62
NTS
UGE
WR
Shaft
-193
<20
398
U.S.
Adobe
04/25/62
Christmas Island, Polynesia
AE
WR
Airdrop
885
190
First U.S. nuclear test at Christmas Island
399
U.S.
Aztec
04/27/62
Christmas Island, Polynesia
AE
WR
Airdrop
795
410
400
U.S.
Black
04/27/62
NTS
UGE
WR
Shaft
-218
<20
401
France
Beryl
05/01/62
Hoggar , Algeria
UGE
WR
Tunnel
20-150
402
U.S.
Arkansas
05/02/62
Christmas Island, Polynesia
AE
WR
Airdrop
1533
1090
403
U.S.
Questa
05/04/62
Christmas Island, Polynesia
AE
WR
Airdrop
1594
670
404
U.S.
Frigate Bird
05/06/62
Pacific
AE
WR
Rocket
2530
600
Warhead in missile launched from Polaris submarine
405
U.S.
Paca
05/07/62
NTS
UGE
WR
Shaft
-258
<20
406
U.S.
Yukon
05/08/62
Christmas Island, Polynesia
AE
WR
Airdrop
878
100
407
U.S.
Mesilla
05/09/62
Christmas Island, Polynesia
AE
WR
Airdrop
747
100
408
U.S.
Arikaree
05/10/62
NTS
UGE
WR
Shaft
-167
<20
409
U.S.
Muskegon
05/11/62
Christmas Island, Polynesia
AE
WR
Airdrop
913
50
410
U.S.
Swordfish
05/11/52
Pacific
UWE
WE
Rocket
-198
<20
Antisubmarine rocket system proof test. DoD test
411
U.S.
Encino
05/12/62
Christmas Island, Polynesia
AE
WR
Airdrop
1679
500
412
U.S.
Aardvark
05/12/62
NTS
UGE
WR
Shaft
-434
40
413
U.S.
Swanee
05/14/62
Christmas Island, Polynesia
AE
WR
Airdrop
896
97
414
U.S.
Eel
05/19/62
NTS
UGE
WR
Shaft
-217
4.5
415
U.S.
Chetco
05/19/62
Christmas Island, Polynesia
AE
WR
Airdrop
2105
73
416
U.S.
White
05/25/62
NTS
UGE
WR
Shaft
-193
<20
417
U.S.
Tanana
05/25/62
Christmas Island, Polynesia
AE
WR
Airdrop
2752
2.6
418
U.S.
Nambe
05/27/62
Christmas Island, Polynesia ¦
AE
WR
Airdrop
2176
43
419
U.S.
Raccoon
06/01/62
NTS
UGE
WR
Shaft
-164
<20
420
U.S.
Packrat
06/06/62
NTS
UGE
WR
Shaft
-262
<20
421
U.S.
Alma
06/08/62
Christmas Island, Polynesia
AE
WR
Airdrop
2702
782
422
U.S.
Truckee
06/09/62
Christmas Island, Polynesia
AE
WR
Airdrop
2124
210
423
U.S.
Yeso
06/10/62
Christmas Island, Polynesia
AE
WR
Airdrop
2537
3000
424
U.S.
Harlem
06/12/62
Christmas Island, Polynesia
AE
WR
Airdrop
4159
1200
425
U.S.
Des Moines
06/13/62
NTS
UGE
WR
Tunnel
-201
2.9
426
U.S.
Rinconada
06/15/62
Christmas Island, Polynesia
AE
WR
Airdrop
2775
800
427
U.S.
Dulce
06/17/62
Christmas Island, Polynesia
AE
WR
Airdrop
2770
52
428
U.S.
Petit
06/19/62
Christmas Island, Polynesia
AE
WR
Airdrop
4570
2.2
429
U.S.
Daman 1
06/21/62
NTS
UGE
WR
Shaft
-260
<20
430
U.S.
Otowi
06/22/62
Christmas Island, Polynesia
AE
WR
Airdrop
2746
81.5
431
U.S.
Bighorn
06/27/62
Christmas Island, Polynesia
AE
WR
Airdrop
3600
7650
432
U.S.
Haymaker
06/27/62
NTS
UGE
WR
Shaft
-408
67
433
U.S.
Marshmallow
06/28/62
NTS
UGE
WE
Tunnel
-311
<20
DoD test
434
(U.S.
Bluestone
06/30/62
Christmas Island, Polynesia
AE
WR
Airdrop
1518
1270
435
U.S.
Sacramento
06/30/62
NTS
UGE
WR
Shaft
-152
<20
436
U.S.
Sedan
07/06/62
NTS
UGE
IPE
Crater
-193
104
Program Plowshare. Excavation experiment. Thermonuclear device
437
U.S.
Little Feller II
07/07/62
NTS
SGE
WE
Surface
0.022
DoD test
438
U.S.
Starfish Prime
07/09/62
Johnston Island , Polynesia
SPE
WE
Rocket
399000
1400
DoD test
439
U.S.
Sunset
07/10/62
Christmas Island, Polynesia
AE
WR
Airdrop
1524
1000
440
U.S.
Pamlico
07/11/62
Christmas Island, Polynesia
AE
WR
Airdrop
4368
3880
Last nuclear test at Christmas Island
441
U.S.
Johnnie Boy
07/11/62
NTS
UGE
WE
Crater
-0.6
0.5
DoD test
442
U.S.
Merrimac
07/13/62
NTS
UGE
WR
Shaft
-416
20-200
443
U.S.
Small Boy
07/14/62
NTS
SGE
WE
Tower
3
1.65
DoD test
444
U.S.
Little Feller I
07/17/62
NTS
SGE
WE
Surface
0.9
0.018
Last atmospheric nuclear test at NTS. DoD test
445
U.S.
Wichita
07/27/62
NTS
UGE
WR
Shaft
-150
<20
446
USSR
08/01/62
STS
AE
WR
Rocket
430
2.4
447
USSR
08/03/62
STS
AE
WR
Rocket
180
1.6
448
USSR
08/04/62
STS
AE
WR
Rocket
390
3.8
449
USSR
08/05/62
NZTS
AE
WR
Airdrop
3600
20900
450
USSR
08/07/62
STS
SGE
WR
Rocket
0
9.9
451
USSR
08/10/62
NZTS
AE
WR
Airdrop
1560
150-1500
452
USSR
08/18/62
STS
AE
WR
Airdrop
705
7.4
453
USSR
08/18/62
STS
AE
WR
Rocket
310
5.8
454
USSR
08/20/62
NZTS
AE
WR
Airdrop
2500
2800
455
USSR
08/21/62
STS
AE
WR
Airdrop
590
20-150
456
USSR
08/22/62
NZTS
AE
WR
Airdrop
1700
1600
457
USSR
08/22/62
NZTS
SWE
WR
Rocket
23
6
458
USSR
08/22/62
STS
AE
WR
Airdrop
740
3
459
USSR
08/23/62
STS
AE
WR
Airdrop
680
2.5
460
U.S.
York
08/24/62
NTS
UGE
WR
Shaft
-227
<20
461
U.S.
Bobac
08/24/62
NTS
UGE
WR
Shaft
-207
<20
462
USSR
08/25/62
NZTS
AE
WR
Airdrop
2980
1500-10000
463
USSR
08/25/62
STS
AE
WR
Airdrop
715
0.001-20
464
USSR
08/27/62
NZTS
AE
WR
Airdrop
3000
4200
465
USSR
08/27/62
STS
AE
WR
Airdrop
245
10.8
466
USSR
08/31/62
STS
AE
WR
Airdrop
700
2.7
467
USSR
09/02/62
NZTS
AE
WR
Airdrop
1320
80
468
U.S.
Raritan
09/06/62
NTS
UGE
WR
Shaft
-157
<20
469
USSR
09/08/62
NZTS
AE
WR
Rocket
1500
1800
470
U.S.
Hyrax
09/14/62
NTS
UGE
WR
Shaft
-216
<20
471
USSR
09/15/62
NZTS
AE
WR
Airdrop
2250
3100
472
USSR
09/16/62
NZTS
AE
WR
Airdrop
2250
3300
473
USSR
09/18/62
NZTS
AE
WR
Airdrop
2000
1350
474
USSR
09/19/62
NZTS
AE
WR
Airdrop
3300
1500-10000
475
U.S.
Peba
09/20/62
NTS
UGE
WR
Shaft
-241
<20
476
USSR
09/21/62
NZTS
AE
WR
Airdrop
3000
2400
477
USSR
09/22/62
STS
SGE
SE
Surface
0.21
478
USSR
09/24/62
STS
AE
WR
Airdrop
630
1.2
479
USSR
09/25/62
STS
SGE
WR
Rocket
0
7
480
USSR
09/25/62
NZTS
AE
WR
Airdrop
4000
19100
481
USSR
09/27/62
NZTS
AE
WR
Airdrop
4170
>10000
482
USSR
09/28/62
STS
AE
FMS
Airdrop
695
1.3
483
U.S.
Allegheny
09/29/62
NTS
UGE
WR
Shaft
-211
<20
484
U.S.
Androscoggin
10/02/62
Johnston Island , Polynesia
AE
WR
Airdrop
3127
75
485
U.S.
Mississippi
10/05/62
NTS
UGE
WR
Shaft
-494
115
486
U.S.
Bumping
10/06/62
Johnston Island , Polynesia
AE
WR
Airdrop
3048
11.3
487
USSR
10/07/62
NZTS
AE
WR
Airdrop
1440
320
488
USSR
10/09/62
STS
AE
WR
Airdrop
645
8.1
489
USSR
10/09/62
NZTS
AE
WR
Airdrop
3000
14
490
USSR
10/10/62
STS
AE
WR
Airdrop
665
9.2
491
U.S.
Roanoke
10/12/62
NTS
UGE
WR
Shaft
-176
<20
492
U.S.
Wolverine
10/12/62
NTS
UGE
WR
Shaft
-73
<20
493
USSR
10/13/62
STS
AE
WR
Airdrop
720
4.9
494
USSR
10/14/62
STS
AE
WR
Airdrop
725
0.001-20
495
U.S.
Chama
10/18/62
Johnston Island , Polynesia
AE
WR
Airdrop
3648
1590
496
U.S.
Tioga
10/18/62
NTS
UGE
WR
Shaft
-61
<20
497
U.S.
Bandicoot
10/19/62
NTS
UGE
WR
Shaft
-244
12.5
498
U.S.
Checkmate
10/20/62
Johnston Island , Polynesia
SPE
WE
Rocket
147300
<20
DoD test
499
USSR
10/20/62
STS
AE
WR
Airdrop
635
6.7
500
USSR
10/22/62
NZTS
AE
WR
Airdrop
3000
8200
501
USSR
K-3
10/22/62
MTR
SPE
WE
Rocket
290000
300
502
U.S.
Bluegill 3 Prime
10/26/62
Johnston Island , Polynesia
HAE
WE
Rocket
48300
200-1000
DoD test
503
U.S.
Santee
10/27/62
NTS
UGE
WR
Shaft
-319
<20
504
U.S.
Calamity
10/27/62
Johnston Island , Polynesia
AE
WR
Airdrop
3590
800
505
USSR
10/27/62
NZTS
AE
WR
Airdrop
1550
260
506
USSR
10/28/62
STS
AE
WR
Airdrop
670
7.8
507
USSR
K-4
10/28/62
MTR
SPE
WE
Rocket
150000
300
508
USSR
10/28/62
STS
AE
WR
Airdrop
645
7.8
509
USSR
10/29/62
NZTS
AE
WR
Airdrop
1550
360
510
U.S.
Housatonic
10/30/62
Johnston Island , Polynesia
AE
WR
Airdrop
3697
8300
511
USSR
10/30/62
STS
SGE
WR
Surface
1.1
512
USSR
10/30/62
NZTS
AE
WR
Airdrop
1500
300
513
USSR
10/31/62
STS
AE
WR
Airdrop
690
10.2
514
U.S.
Kingfish
11/01/62
Johnston Island , Polynesia
SPE
WE
Rocket
96600
200-1000
DoD test
515
USSR
11/01/62
STS
AE
WR
Airdrop
700
3
516
USSR
11/01/62
NZTS
AE
WR
Airdrop
1500
250
517
USSR
K-5
11/01/62
MTR
HAE
WE
Rocket
59000
300
518
USSR
11/03/62
NZTS
AE
WR
Airdrop
1500
400
519
USSR
11/03/62
NZTS
AE
WR
Airdrop
4000
45
520
USSR
11/03/62
STS
AE
WR
Airdrop
710
4.7
521
U.S.
Tightrope
11/04/62
Johnston Island , Polynesia
AE
WE
Rocket
20930
<20
Last nuclear test at Johnston Island . DoD test
522
USSR
11/04/62
STS
AE
WR
Airdrop
700
8.4
523
USSR
11/05/62
STS
SGE
WE
Tower
15
0.4
524
U.S.
St.Lawrence
11/09/62
NTS
UGE
WR
Shaft
-166
<20
525
USSR
11/11/62
STS
SGE
WR
Tower
8
0.055
526
USSR
11/13/62
STS
SGE
WR
Surface
< 0.001
527
USSR
11/14/62
STS
AE
WR
Airdrop
660
11.5
528
U.S.
Gundi
11/15/62
NTS
UGE
WR
Shaft
-244
<20
529
USSR
11/17/62
STS
AE
WR
Airdrop
715
18.5
530
USSR
11/24/62
STS
SGE
SE
Surface
< 0.001
531
USSR
11/26/62
STS
SGE
SE
Surface
0.031
532
U.S.
Anacostia
11/27/62
NTS
UGE
PDD
Shaft
-228
<20
Program Plowshare. Device development
533
USSR
12/01/62
STS
AE
WR
Airdrop
680
2.4
534
U.S.
Taunton
12/04/62
NTS
UGE
WR
Shaft
-228
<20
535
UK
Tendrac
12/07/62
NTS
UGE
WR
Shaft
-303
<20
536
U.S.
Madison
12/12/62
NTS
UGE
WR
Tunnel
-402
<20
537
U.S.
Numbat
12/12/62
NTS
UGE
WR
Shaft
-232
<20
538
U.S.
Manatee
12/14/62
NTS
UGE
WR
Shaft
-58
<20
539
USSR
12/18/62
NZTS
AE
WR
Airdrop
1600
110
540
USSR
12/18/62
NZTS
AE
FMS
Airdrop
1500
69
541
USSR
12/20/62
NZTS
AE
FMS
Airdrop
1070
8.3
542
USSR
12/22/62
NZTS
AE
WR
Airdrop
1050
6.3
543
USSR
12/23/62
NZTS
AE
WR
Airdrop
1460
430
544
USSR
12/23/62
NZTS
AE
WR
Airdrop
1470
8.3
545
USSR
12/23/62
NZTS
AE
WR
Airdrop
1270
2.4
546
USSR
12/23/62
STS
SGE
SE
Surface
< 0.001
547
USSR
12/24/62
STS
SGE
SE
Surface
0.007
548
USSR
12/24/62
STS
SGE
SE
Surface
0.028
549
USSR
12/24/62
NZTS
AE
WR
Airdrop
1320
1100
550
USSR
12/24/62
NZTS
AE
WR
Airdrop
3750
22300
551
USSR
12/25/62
NZTS
AE
WR
Airdrop
2250
3100
552
USSR
12/25/62
NZTS
AE
WR
Airdrop
1050
8.5
Last Soviet atmospheric nuclear explosion