Fact Sheet
Public Affairs Office
Washington, D. C. 20305
1 September 1981
Radiation Safety Procedures
Radiological safety was a paramount consideration of the operation and overall was the responsibility of the US Naval Radiological Defense Laboratory (NRDL). Radiation Safety (Rad-safe) procedures included measures to minimize exposures to personnel, to measure and evaluate radiological hazards and contaminated areas, to control exposures to personnel and the spread of radioactive contamination from samples, equipment and other materials, and the documentation of levels of exposure and contamination. For the duration of the operation, an exposure limitation of 3.9 roentgen (R) was set. In addition, levels were,specifically established for radioactive contamination of clothing and personal equipment, food, water, air, ships' surfaces, equipment and materials,
An important part of the Rad-safe procedures was the personnel dosimetry program. Nearly all individuals involved in the operation were issued a film badge to measure any exposure received during the operation. Personnel whose duties were such that exposure to radiation was possible (such as sampling water, recovering equipment or instruments) were issued additional film badges on a daily basis. One of the vessels, the USS WRIGHT, contained a film processing center where badges were read and personnel exposures were recorded. Over the period of the operation, approximately 10,000 film badges were issued. These included operational, daily, calibration, and scientific project badging.
Personnel Exposures
The rad-safe procedures established for the operation were highly effective in keeping personnel exposures to a minimum. The following table summarizes the recorded personnel radiation exposures at WIGWAM based upon a 1979 review of dosimetry:
WIGWAM EXPOSURES
Exposures in Roentgens
| Wigwam | Total
Issued |
Dose
Unavail | Zero
Exposure |
.100-
.165 | .200-
.280 | 3.15-
.385 | .425 |
| Badges | 6732 | 229 |
6141 | 329 | 19 | 13 | 1* |
| % in each group | 100% | 3.4% | 91.2% |
4.9% | 0.3% | 0.2% | 0.01% |
*The highest exposure was received by a member (an air sampler pilot) of the aviation support provided through Naval Air Station, San Diego.
The average exposure for the 362 WIGWAM individuals with non-zero exposures was 0.129 R. which is about the average annual exposure to naturally occurring background radiation in the United States.
Data compiled at the time of the test indicated that operational badges showed 350 positive recorded gamma exposures with a maximum reading of 0.425 R. This earlier compilation indicated that the average exposure for these 350 badges was 0.132 R. Although the results of the two data reviews differ slightly, they both confirm that more than 90 percent of all doses at WIGWAM were zero and that recorded exposures at WIGWAM ranged from 0.100 R to 0.425 R.
The two vessels (YAG-39 and YAG-40) stationed downwind of the detonation point were subjected to contamination by water droplets of the base surge. None of the YAG personnel received significant exposures. Both of these vessels had been specially configured and shielded for the purpose of crossing contaminated areas although only YAG-39 had a seawater washdown system. The deck surface radiation reading on YAC-39 reached levels in excess of 400 R/hr about 17 minutes after the detonation. The washdown system that had been installed to decontaminate the surfaces reduced this level to 0.040 R per hour 30 minutes after the detonation. Recorded shipboard levels were less aboard YAC-40. Both of these vessels had 48 assigned personnel. However, at the time of detonation only about 12 crewmembers and project personnel were aboard each YAG. Six crewmembers aboard YAG and one crewmember aboard JiNG 40 received recorded exposures other than zero. In each instance, recorded film badge readings for crewmembers did not exceed 0.130 R. One unidentified, non-crewmember aboard YAG-40 received an exposure of 0.200 R.
Operation Wigwam