Beyond "ground zero": Nevada's radioactive pollution

Test: ANTLER

Date: 09/15/61 Sponsor: LRL

Time: 1000 PST Depth of Burial: 1,320 ft

Location: NTS U12e.03 Purpose: Weapons Related

Type: Tunnel Yield: 2.6 kt

Release Type of Detected: Offsite Release: Test

Test Release at R+12 Hours, in Curies: 2.1 x 10 5

Isotopes Identified in the Release: 131 I, 133 I, 135 I, and 140 Ba/140 La
Cloud Direction: Northerly over Highway 25, Reed, Diablo, and Warm Springs, Nevada
Maximum Activity Detected in Air Offsite: 28 picocuries of gross beta activity per cubic meter of air at Diablo, Nevada
Maximum Gamma Exposure Rate Detected Offsite: 12.5 mR/h at Twin Springs Ranch, Nevada
Maximum Iodine Level Detected Offsite: 1.4 picocuries of 131 I per cubic meter of air,
34 picocuries of 133 I per cubic meter of air, and 150 picocuries of 135 I per cubic meter of air at Diablo, Nevada
Maximum Distance Radiation Detected Offsite: 1.5 mR/h at 21.1 miles northeast of the junction of Highway 6 and Highway 25 (Nevada)
Release Summary: Venting occurred at the tunnel portal at H+2 seconds and lasted for an unknown duration. A secondary steam explosion was observed from eight to ten minutes following the detonation.
References: (A) (C) (E) (F) (G) (H) (AY) (DA) (GA)

Test: GNOME

Date: 12/10/61 Sponsor: LRL

Time: 1200 MST Depth of Burial: 1,185 ft

Location: Carlsbad, NM Purpose: Plowshare

Type: Shaft Yield: 3.0 kt

Release Type of Detected: Offsite Release: Test

Test Release at R+12 Hours: Release not quantified

Isotopes Identified in the Release: 131 I, 133 I, 135 I, 137 Cs, 140 Ba/140 La, and noble gases
Cloud Direction: Northwesterly direction crossing over Highway 128 and Highway 31
(New Mexico)
Maximum Activity Detected in Air Offsite: 160 picocuries of gross beta activity per cubic meter of air at the IMCC Mine, New Mexico
Maximum Gamma Exposure Rate Detected Offsite: 1,400 mR/h at 3.5 miles west of the junction of Highway 31 and 128
Maximum Iodine Level Detected Offsite: Near Carlsbad, New Mexico, 1.7 picocuries of 131 I per cubic meter of air, 18 picocuries of 133 I per cubic meter of air, and 3.5 picocuries of 135 I per cubic meter of air at the IMCC Processing Plant
Maximum Distance Radiation Detected Offsite: 0.3 mR/h at Roswell, New Mexico
Release Summary: Radiation was detected at the blast door near the bottom of the shaft less than one minute following the explosion and at the shaft collar three minutes and 40 seconds after the detonation. At approximately seven minutes after the detonation, gray smoke, steam, and associated radioactivity surged from the shaft opening. By 11 minutes following the explosion, copious quantities of steam were issuing from both shaft and ventilation lines. A large flow continued for about 30 minutes before gradually decreasing. A small flow was still detected the following day. The radioactive elements that vented through the shaft were volatiles and noble gases.
References: (A) (E) (H) (AY) (DC)

Test: FEATHER

Date: 12/22/61 Sponsor: LRL

Time: 0830 PST Depth of Burial: 812 ft

Location: NTS U12b.08 Purpose: Weapons Related

Type: Tunnel Yield: 150 tons

Release Type of Detected: Offsite Release: Test

Test Release at R+12 Hours, in Curies: 3.8 x 10 2

Isotopes Identified in the Release: 103 Ru,131 I, 133 I, 135 I, 140 La, and 141 Ce
Cloud Direction: Southwesterly over Death Valley Junction, California
Maximum Activity Detected in Air Offsite: 440 picocuries of gross beta activity per cubic meter of air at Bettle’s Farm, Nevada
Maximum Gamma Exposure Rate Detected Offsite: 0.08 mR/h at Death Valley Junction, California
Maximum Iodine Level Detected Offsite: 290 picocuries of 133 I per cubic meter of air and 1,000 picocuries of 135 I per cubic meter of air at Bettle’s Farm, Nevada
Maximum Distance Radiation Detected Offsite: 0.01 mR/h at 1.5 miles west to one mile south of Death Valley Junction, California
Release Summary: At H hour, a small cloud rose from the tunnel portal and vent pipes on top of the mesa and endured for 11 minutes. Monitoring data showed the cloud traveled in a straight path on a heading of 190 degrees, passing just east of Carrara, Nevada. South of Carrara, the path changed to the southeast, passing over Death Valley Junction and eventually reaching Ash Meadows, Nevada.
References: (A) (C) (E) (F) (G) (H) (AY) (DA) (GC)

Test: PAMPAS

Date: 03/01/62 Sponsor: LASL/UK

Time: 1110 PST Depth of Burial: 1,200 ft

Location: NTS U3al Purpose: Joint US-UK

Type: Shaft Yield: 9.5 kt

Release Type of Test/Prompt Particle

Detected: Offsite Release: Sampling and Drillback

Test Release at R+12 Hours, in Curies: 2.0 x 10 3

Isotopes Identified in the Release: 95 Nb, 103 Ru, 131 I, 133 I, 135 I, 140 La, and 141 Ce

Cloud Direction: Northeasterly over Highway 25 (Nevada)

Maximum Activity Detected in Air Offsite: 1,700 picocuries of gross beta activity per cubic meter of air at Penoyer, Nevada

Maximum Gamma Exposure Rate Detected Offsite: 0.22 mR/h at Penoyer, Nevada

Maximum Iodine Level Detected Offsite: 9 picocuries of 131 I per cubic meter of air,

220 picocuries of 133 I per cubic meter of air, and 350 picocuries of 135 I per cubic meter of air at Gunderson’s Ranch, Penoyer, Nevada

Maximum Distance Radiation Detected Offsite: 0.08 mR/h at 17.7 miles north of Highway 25 in Sand Springs Valley, Nevada

Drillback Release Activity at Time of Release: Some

Release Summary: A test release occurred from a broken sampling line at zero time and lasted for 20 minutes. The release of radioactivity occurred with winds from the south carrying the cloud north on about a ten degree trajectory.

Some radiation was detected in the area surrounding surface ground zero from gaseous

radioactivity released during postshot drilling.

References: (A) (B) (E) (F) (G) (H) (AY) (DA) (GE)

Test: DANNY BOY

Date: 03/05/62 Sponsor: DoD/LRL

Time: 1015 PST Depth of Burial: 110 ft

Location: NTS U18a Purpose: Weapons Effects

Type: Crater Yield: 430 tons

Release Type of Detected: Offsite Release: Test/Crater

Test Release at R+12 Hours, in Curies: 8.5 x 10 5

Isotopes Identified in the Release: 91 Sr, 103 Ru, 131 I, 133 I, 135 I, 132 Te, and 140 Ba/140 La

Cloud Direction: Northerly over Highway 6, west of Warm Springs, Nevada

Maximum Activity Detected in Air Offsite: 1,000 picocuries of gross beta activity per cubic meter of air at Warm Springs, Nevada

Maximum Gamma Exposure Rate Detected Offsite: 3.2 mR/h 17.7 miles west of Warm Springs, Nevada

Maximum Iodine Level Detected Offsite: 6.9 picocuries of 131 I per cubic meter of air,

220 picocuries of 133 I per cubic meter of air, and 350 picocuries of 135 I per cubic meter of air at Warm Springs, Nevada

Maximum Distance Radiation Detected Offsite: 0.02 mR/h at Carver’s Restaurant, Nevada

Release Summary: A persistent cloud was produced during the blow out crater formation

containing appreciable quantities of radioactivity associated with particulates. The total release,at the time of release, was 1.4 x 10 10 curies.

References: (A) (E) (F) (G) (H) (U) (V) (AY) (DA) (GE)

Test: PLATTE

Date: 04/14/62 Sponsor: LRL

Time: 1000 PST Depth of Burial: 560 ft

Location: NTS U12k.01 Purpose: Weapons Related

Type: Tunnel Yield: 1.85 kt

Release Type of Test and Test/Prompt

Detected: Offsite Release: Particle Sampling

Test Release at R+12 Hours, in Curies: 1.9 x 10 6

Isotopes Identified in the Release: 40 K, 95 Zr/95 Nb, 103 Ru, 105 Ru, 131 I, 133 I, 135 I, 132 Te, 140 Ba/140 La, 141 Ce, and 144 Ce

Cloud Direction: Northerly over Highway 25 (Nevada) at a bearing of approximately 20

degrees

Maximum Activity Detected in Air Offsite: 34,000 picocuries of gross beta activity per cubic meter of air at Queen City Summit, Nevada (unpopulated)

Maximum Gamma Exposure Rate Detected Offsite: 47 mR/h at Queen City Summit, Nevada

Maximum Iodine Level Detected Offsite: 3,500 picocuries of 131 I per cubic meter of air, 23,000 picocuries of 133 I per cubic meter of air, and 37,000 picocuries of 135 I per cubic meter of air at Queen City Summit, Nevada

Maximum Distance Radiation Detected Offsite: 0.10 mR/h at 28.1 miles northeast of

Currant, Nevada

Release Summary: Venting occurred at the tunnel portal, through fissures, and at the sampling hole at H+1.5 seconds. The fissures were created on the side of the hill, and radial cracks formed on top of the hill. A persistent cloud was produced containing appreciable quantities of radioactivity associated with particles.

References: (A) (C) (E) (F) (G) (H) (AY) (DA) (GG)

Test: EEL

Date: 05/19/62 Sponsor: LRL

Time: 0800 PDT Depth of Burial: 714 ft

Location: NTS U9m Purpose: Weapons Related

Type: Shaft Yield: 4.5 kt

Release Type of Test/Prompt Particle

Detected: Offsite Release: Sampling

Test Release at R+12 Hours, in Curies: 1.9 x 10 6

Isotopes Identified in the Release: 95 Zr/95 Nb, 103 Ru, 106 Ru,105 Rh, 131 I, 133 I, 135 I, 132 Te, 140 Ba/140 La, 141 Ce, and 144 Ce

Cloud Direction: Northerly towards Eureka, Nevada

Maximum Activity Detected in Air Offsite: 3,400 picocuries of gross beta activity per cubic meter of air at Currant, Nevada

Maximum Gamma Exposure Rate Detected Offsite: 10 mR/h at 5.9 miles northwest of Queen City Summit, Nevada (unpopulated)

Maximum Iodine Level Detected Offsite: 5.6 picocuries of 131 I per cubic meter of air, and 23 picocuries of 133 I per cubic meter of air at Currant, Nevada, and 26 picocuries of 135 I percubic meter of air at Gunderson’s Ranch, Nevada

Maximum Distance Radiation Detected Offsite: 0.02 mR/h at 19 miles west of Ely, Nevada,on Highway 50

Release Summary: Venting, in the form of a geyser, occurred at H+10 seconds from satellite hole U9m-2 and continued steadily until H+19 minutes, 42 seconds. A similar venting occurred at H+15 seconds from satellite hole U9m-3 and lasted until H+21 minutes. The venting ceased with crater subsidence.

References: (A) (C) (E) (F) (G) (H) (AY) (CC) (DA) (GH)

Test: DES MOINES

Date: 06/13/62 Sponsor: LRL

Time: 1400 PDT Depth of Burial: 660 ft

Location: NTS U12j.01 Purpose: Weapons Related

Type: Tunnel Yield: 2.9 kt

Release Type of Test and Test/Prompt

Detected: Offsite Release: Particle Sampling

Test Release at R+12 Hours, in Curies: 1.1 x 10 7

Isotopes Identified in the Release: 103 Ru, 106 Ru/106 Rh, 131 I, 133 I, 135 I, 132 Te, and

140 Ba/140 La

Cloud Direction: Generally northeasterly over Queen City Summit, Nevada (unpopulated)

Maximum Activity Detected in Air Offsite: 15,000 picocuries of gross beta activity per cubic meter of air at Queen City Summit, Nevada, (unpopulated), and 5,900 picocuries of gross beta activity per cubic meter of air at Diablo, Nevada

Maximum Gamma Exposure Rate Detected Offsite: 160 mR/h at Queen City Summit,

Nevada

Maximum Iodine Level Detected Offsite: 1,400 picocuries of 131 I per cubic meter of air, 16,000 picocuries of 133 I per cubic meter of air, and 230,000 picocuries of 135 I per cubic meter of air at Queen City Summit, Nevada

Maximum Distance Radiation Detected Offsite: 0.6 mR/h at 18.6 miles west of Ely, Nevada, on Highway 50 (approximately 163 miles from the detonation site)

Release Summary: Venting began at H+0.2 seconds on top of the hill at surface ground zero, then from the sampling hole on the face of the hill, and finally through the portal. The duration of the release was approximately five minutes. The test vented out of the tunnel mouth with sufficient pressure and flow rate that radioactive debris was projected entirely across the canyon and deposited on the slope behind a trailer shelter.

The test caused 131 I milk contamination in the following locations: Adavan, Nevada, 360

picocuries per liter on June 20; Elko, Nevada, 610 picocuries per liter on June 22; and Spokane, Washington, 1,200 picocuries per liter on June 20. All measurements were made from samples taken from fresh milk except those at Spokane that were made from pooled milk at a pasteurizing plant.

References: (A) (C) (E) (F) (G) (H) (M) (AY) (DA) (GI)

Test: SEDAN

Date: 07/06/62 Sponsor: LRL

Time: 1000 PDT Depth of Burial: 635 ft

Location: NTS U10h Purpose: Plowshare

Type: Crater Yield: 104 kt

Release Type of

Detected: Offsite Release: Test/Crater

Test Release at R+12 Hours, in Curies: 1.5 x 10 7

Isotopes Identified in the Release: 7 Be, 24 Na, 56 Mn, 103 Ru, 131 I, 132 I,133 I, 135 I, 132 Te, 140 Ba/140 La, 181 W, 187 W, 188 W, and tracers

Cloud Direction: Northeasterly

Maximum Activity Detected in Air Offsite: 13,000 picocuries of gross beta activity per cubic meter of air at Diablo, Nevada

Maximum Gamma Exposure Rate Detected Offsite: 324 mR/h at Diablo, Nevada, and

1,960 mR/h near Queen City Summit, Nevada (unpopulated)

Maximum Iodine Level Detected Offsite: 3,700 picocuries of 131 I per cubic meter of air, 13,000 picocuries of 133 I per cubic meter of air, and 60,000 picocuries of 135 I per cubic meter of air at Diablo, Nevada

Maximum Distance Radiation Detected Offsite: 0.7 mR/h near McGill, Nevada (north of Ely)

Release Summary: A persistent cloud containing appreciable quantities of radioactivity,

including particulates, was produced during the cratering process. Fallout was documented to a distance of approximately 200 statute miles downwind.

The significant contributors to the gamma exposure rate at H+24 hours were fission products, 187 W, and 24 Na. Approximately 42% of the gamma exposure rate at H+24 hours was the result of fission products, 55% was from 187 W, 2% was from 24 Na, and less than 1% was from 181 W, 188 W, 7 Be, 56 Mn, and tracers.

References: (A) (C) (E) (F) (G) (H) (AR) (DD)

Test: JOHNNIE BOY

Date: 07/11/62 Sponsor: DoD

Time: 0945 PDT Depth of Burial: 23 in

Location: NTS Area 18 Purpose: Weapons Effects

Type: Crater Yield: 500 tons

Release Type of Detected: Offsite Release: Test/Crater

Test Release: Atmospheric

Isotopes Identified in the Release: 131 I, 133 I, 135 I, 132 Te, and 140 Ba/140 La

Cloud Direction: Northerly; subsequently divided into two portions

Maximum Activity Detected in Air Offsite: 23,000 picocuries of gross beta activity per cubic meter of air at Twin Springs Ranch, Nevada

Maximum Gamma Exposure Rate Detected Offsite: 3.0 mR/h near the Rattlesnake
Maintenance Station, Nevada, by ground monitoring; 3.8 mR/h on a recording radiation monitor at Twin Springs Ranch, Nevada

Maximum Iodine Level Detected Offsite: 500 picocuries of 131 I per cubic meter of air,
920 picocuries of 133 I, per cubic meter of air, and 2,300 picocuries of 135 I per cubic meter of air at Twin Springs, Nevada
Maximum Distance Radiation Detected Offsite: 3.0 mR/h at 11 miles northeast of Lockes, Nevada
Release Summary: A persistent cloud containing appreciable quantities of radioactivity,
including particulates, was produced during the cratering process.
Detonation of this test resulted in the formation of a radioactive cloud that moved north from the test site. This cloud split into two portions. The lower portion traveled slightly west of north to the area of Highway 6 between Tonopah and Warm Springs, Nevada, then traveled east of north after assuming a width of 25-30 miles; the higher portion, above 11,000 ft mean sea level (MSL), traveled east of north.

References: (A) (E) (F) (AR) (GK)

Test: SMALL BOY
Date: 07/14/62                                                                                 Sponsor: DoD
Time: 1130 PDT                                                                               Depth of Burial: 10 ft above ground
Location: NTS Area 5                                                                       Purpose: Weapons Effects
Type: Tower Yield: Low
Release Type of Detected: Offsite                                                     Release: Test/Surface
Test Release: Atmospheric
Isotopes Identified in the Release: 95 Zr/95 Nb, 103 Ru, 131 I, 132 Te, and 140 Ba/140 La
Cloud Direction: Northeasterly
Maximum Activity Detected in Air Offsite: 140,000 picocuries of gross beta activity per cubic
meter of air at Elko, Nevada
Maximum Gamma Exposure Rate Detected Offsite: 14 mR/h at 13 miles south of Alamo,
Nevada
Maximum Iodine Level Detected Offsite: 1,100 picocuries of 131 I per cubic meter of air at
Caliente, Nevada, and 3,500 picocuries of 131 I per liter in milk at Caliente, Nevada
Maximum Distance Radiation Detected Offsite: 0.02 mR/h at seven miles south of Parowan,
Utah, on Highway 143
Release Summary: This test resulted in the formation of a radioactive cloud that moved east
from surface ground zero and crossed Highway 93 south of Alamo, Nevada. During the night of
July 14 and the morning of July 15, the cloud moved further east into Utah, and it reached such
low levels that it was detected only in small segments by ground monitoring.
References: (A) (E) (F) (AR) (GL)

Test: BANDICOOT
Date: 10/19/62                                                             Sponsor: LASL
Time: 1100 PDT                                                         Depth of Burial: 800 ft
Location: NTS U3bj                                                     Purpose: Weapons Related
Type: Shaft                                                                   Yield: 12.5 kt
Release Type of Detected: Offsite                                Release: Test
Test Release at R+12 Hours, in Curies: 3.0 x 10 6
Isotopes Identified in the Release: 95 Zr/95 Nb, 103 Ru, 131 I, 133 I, 135 I, 132 Te, and 140 Ba/140 La
Cloud Direction: Northerly for the lower part of the cloud; south southwesterly for the upper
portion of the cloud
Maximum Activity Detected in Air Offsite: 52,000 picocuries of gross beta activity per cubic
meter of air at Death Valley Junction, California
Maximum Gamma Exposure Rate Detected Offsite: Greater than 20 mR/h on Highway 95,
seven miles west of the Mercury Junction (Nevada)*
Maximum Iodine Level Detected Offsite: 310 picocuries of 131 I per cubic meter of air, and
2,500 picocuries of 135 I per cubic meter of air at Lathrop Wells, Nevada; maximum 131 I level in
milk, 160 picocuries per liter on October 23, 1962, at Springdale, Nevada
Maximum Distance Radiation Detected Offsite: 0.01 mR/h at 14.5 miles south of Shoshone,
California
Release Summary: At H+5 seconds a persistent cloud was produced containing appreciable
quantities of radioactivity associated with particulates. This test venting, that lasted for five
minutes, was from a ground fault near the surface ground zero area.
The radioactive cloud split into two portions. The lower portion of the cloud traveled in a
north-northeasterly direction to Area 9 where it remained stagnant, then moved slowly across
Flat Top Mesa and north to the Area 12 Compound. The cloud dispersed in the valleys north of
the Nevada Test Site. No exposures to people were detected.
The upper portion of the cloud traveled in a southerly direction and traversed a course over
Camp Mercury, Cactus Springs, Indian Springs, Lathrop Wells and Highway 95 (Nevada). Upon
crossing Highway 95, the cloud was nine miles wide, diffusing rapidly, and proceeding
southwest, passing over the Los Angeles, California area.
References: (A) (C) (E) (G) (H) (AR) (DB) (GO)
______________________________
*Upper limit of measuring instrument.

Test: DOUBLE TRACKS
Date: 05/15/63                                                 Sponsor: Joint US-UK
Time: 0255 PDT                                                 Depth of Burial: Not Applicable
Location: NAFR                                                 Purpose: Storage-Transportation
Type: Surface Yield: Zero
Release Type of
Detected: Offsite Release: Test/Plutonium Dispersal
Test Release at R+12 Hours, in Curies: Unknown
Maximum Activity Detected in Air Offsite: Estimated 12.1 disintegrations per minute per
cubic meter (alpha) at Scotty’s Junction, Nevada
Maximum Gamma Exposure Rate Detected Offsite: No offsite gamma radiation was
detected.
Maximum Iodine Level Detected Offsite: Non-nuclear experiment, no iodine was produced.
Maximum Distance Radiation Detected Offsite: Alpha activity detected on air samplers at
Beatty, Nevada and Scotty’s Junction, Nevada
Release Summary: This test was part of Operation Roller Coaster. Four storage and
transportation tests on the NAFR were conducted as Operation Roller Coaster during May and
June 1963.
DOUBLE TRACKS was a non-nuclear experiment that took place on Stonewall Flats at
0255 hours on May 15, 1963. The purpose of this test was to determine data on debris
scattering. To accomplish this purpose, conventional high explosives were used to scatter an
alpha-emitting isotope into the atmosphere.
Filters from air samplers taken at populated locations indicated a maximum concentration of
12.1 disintegrations per minute/cubic meter at Scotty’s Junction, Nevada. (The air sample with
this highest reading was from an air sampler with a burned out motor, and the total air flow had
to be estimated.) A filter from a sampler run from 1245 hours May 14 to 1300 hours on May 15
in Beatty, Nevada, showed 11.3 disintegrations per minute per cubic meter. Other filters from
populated locations showed concentrations above the 0.04 disintegrations per minute per cubic
meter background level.
References: (E) (AZ) (DE) (GP)

Test: CLEAN SLATE I
Date: 05/25/63                                                             Sponsor: Joint US-UK
Time: 0417 PDT                                                         Depth of Burial: Not Applicable
Location: NAFR                                                         Purpose: Storage-Transportation
Type: Surface Yield: Zero
Release Type of
Detected: Offsite                                                         Release: Test/Plutonium Dispersal
Test Release at R+12 Hours, in Curies: Unknown
Maximum Activity Detected in Air Offsite: 0.32 disintegrations per minute per cubic meter
(alpha) at Lathrop Wells, Nevada
Maximum Gamma Exposure Rate Detected Offsite: No offsite gamma radiation was
detected.
Maximum Iodine Level Detected Offsite: Non-nuclear experiment, no iodine was produced.
Release Summary: The test was part of Operation Roller Coaster. Four storage and
transportation tests on the NAFR were conducted as Operation Roller Coaster during May and
June 1963.At 0417 hours on May 25, 1963, CLEAN SLATE I, a conventional high explosive device with a
plutonium-239 component, was detonated at Cactus Flats, Nevada. The purpose of this
experiment was to determine data on the extent and concentration of alpha-emitting debris
scattering from a conventional high-explosive device equipped with one or more alpha-emitting
components.
Due to fluctuating wind patterns, air filters from populated areas northeast and southeast of
surface ground zero showed small concentrations of alpha-emitting material with a maximum
activity of 0.32 disintegrations per minute per cubic meter of air at Lathrop Wells, Nevada.
Filters from populated areas (including Hiko, Lund, Mesquite, Pioche, Tonopah, Warm Springs,
Las Vegas, Furnace Creek, and Lathrop Wells) showed small concentrations of contaminated
material.
References: (E) (AZ) (DE) (GQ)

Test: CLEAN SLATE II
Date: 05/31/63                                                     Sponsor: Joint US-UK
Time: 0347 PDT                                                     Depth of Burial: Not Applicable
Location: NAFR                                                     Purpose: Storage-Transportation
Type: Surface Yield: Zero
Release Type of
Detected: Onsite Only Release: Test/Plutonium Dispersal
Test Release at R+12 Hours, in Curies: Unknown
Release Summary: This test was part of Operation Roller Coaster. Four storage and
transportation tests on the NAFR were conducted as Operation Roller Coaster during May and
June 1963.CLEAN SLATE II, the third non-nuclear experiment of Operation Roller Coaster, was carried
out on Cactus Flats, Nevada, at 0347 hours, May 31, 1963. The purpose of this detonation was
to determine data on the extent and concentration of debris scattering from a conventional
high-explosive device equipped with one or more alpha-emitting isotope components.
Air filter results from 31 permanent stations surrounding the test area indicated that any material
released from CLEAN SLATE II was confined to the Cactus Flats location.
References: (E) (AZ) (DE) (GR)

Test: YUBA
Date: 06/05/63                                                         Sponsor: LRL
Time: 1000 PDT                                                     Depth of Burial: 795 ft
Location: NTS U12b.10                                         Purpose: Weapons Related
Type: Tunnel Yield: 3.1 kt
Release Offsite                                                             Type of Test/Prompt Particle
Detected: (Drillback Only) Release: Sampling and Drillback
Test Release at R+12 Hours, in Curies: 1.1 x 10 2
Isotopes Identified in the Release: 88 Kr, 131 I, 133 I, 135 I, 135 Xe, and 138 Cs
Drillback Release Activity at Time of Release, in Curies: 7.2 x 10 4
Isotopes Identified in the Release: 131 I, 133 I, 135 I, 133 Xe, and 135 Xe
Maximum Activity Detected in Air Offsite: No fresh fission products were detected.
Maximum Gamma Exposure Rate Detected Offsite: No radiation intensities above
background levels were measured.
Maximum Iodine Level Detected Offsite: No iodine was detected.
Maximum Distance Radiation Detected Offsite: Two miles offsite at Lathrop Wells, Nevada
(detected from the drillback release)
Release Summary: A test release occurred from the Rad-chem pipe.
A drillback release from a postshot drill hole occurred on June 7, 1963, and lasted for 100 hours.
References: (C) (E) (G) (H) (AR) (DB) (GS)

Test: APSHAPA
Date: 06/06/63 Sponsor: LRL
Time: 0958 PDT Depth of Burial: 295 ft
Location: NTS U9ai Purpose: Weapons Related
Type: Shaft Yield: Low
Release Type of
Detected: Onsite Only Release: Test and Drillback
Test Release at R+12 Hours, in Curies: 3.8
Drillback Release Activity at Time of Release, in Curies: 3.0 x 10 2
133 Xe and 135 Xe in curies: 3.0 x 10 2
Release Summary: A test release from the surface ground zero area occurred at H+10 minutes
and lasted for 25 minutes.
A drillback release from a postshot drill hole occurred on June 6, 1963, and lasted for four hours.
References: (C) (E) (H) (AR) (JH)

Test: CLEAN SLATE III
Date: 06/09/63                                                     Sponsor: Joint US-UK
Time: 0330 PDT                                                 Depth of Burial: Not Applicable
Location: NAFR                                                 Purpose: Storage-Transportation
Type: Surface Yield: Zero
Release Type of Detected: Offsite                           Release: Test/Plutonium Dispersal
Test Release at R+12 Hours, in Curies: Unknown
Maximum Activity Detected in Air Offsite: Not above background; a maximum of
1.64 x 10 -13 microcuries per cubic centimeter was measured on the Test Range Complex.
Maximum Gamma Exposure Rate Detected Offsite: No offsite gamma radiation was
detected.
Maximum Iodine Level Detected Offsite: Non-nuclear experiment, no iodine was produced.
Maximum Distance Radiation Detected Offsite: 47.8 + 1.5 disintegrations per minute per
square foot of 239, 240 Pu on a film collector at Springdale, Utah
Release Summary: This test was part of Operation Roller Coaster. Four storage and
transportation tests on the NAFR were conducted as Operation Roller Coaster during May and
June 1963.
At 0330 hours on June 9, 1963, the CLEAN SLATE III test was conducted at Cactus Flats,
Nevada. The purpose of this test was to determine data on the extent and concentration of
alpha-emitting debris scattering from a conventional high-explosive device with one or more
radioactive components. This was the fourth and last test of the Roller Coaster series.
Careful ground monitoring to the southeast and southwest of surface ground zero failed to show
any readings above background levels. The area was monitored after heavy morning and
afternoon rains on June 9, 1963.
References: (E) (AZ) (DE) (GT)

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