What the document says
This topical report was written as a primer for military personnel responsible for plutonium bearing weapons and for cleaning up areas contaminated by a weapons accident. The study group built it from a search of past and current documents, manuals and regulations, from personal contact with specialists, and from meetings and symposia held during the early months of the work. Seven sections cover the general hazard, U.S. policy and exposure limits, the physical behavior of dispersed plutonium, the biology of contamination, calculations of inhaled plutonium in the body, foreign standards and decontamination methods. References are current as of December 1972.
The authors treat inhalation as the main route of harm. When a fire or impact is severe enough to breach a weapon's containment, plutonium is dispersed, generally as oxides. Material on the ground does not stay fixed in place, since it can be stirred back into the air by natural or human activity, so the report states that long term occupancy of a contaminated area is a greater danger to a population than passage of the first cloud. Working from the 1965 lung model and a proposed 1973 model, the report concludes the lung is the critical organ rather than the lymph nodes or lymphatic system.
The policy section traces limits from the early X-ray and radium era through the Manhattan District, where plutonium body burden standards were set by comparison with radium and bone was treated as the organ at risk. For weapons accidents, joint DOD and AEC policy in TP 20-5 says areas contaminated above 1000 micrograms per square meter should be reduced below that level where it is possible and consistent with reasonable cost and effort. Army guidance defines terrain above 3500 micrograms per square meter as a chronic hazard area that gets first priority. The closing section covers decontamination methods for hard surfaces and land areas.
Key points
- 01Inhalation of airborne plutonium particles is treated as the primary hazard, because material held in the lung delivers alpha radiation and stays there a long time.
- 02Based on the 1965 lung model and the proposed 1973 model, the report concludes the lung is the critical organ, not the lymph nodes or lymphatic system.
- 03Joint DOD and AEC policy TP 20-5, dated 22 May 1968 with Change 1 of 15 August 1969, sets 1000 micrograms per square meter as the level for decontamination after a weapons accident.
- 04Army manual FM 3-15 defines terrain above 3500 micrograms per square meter as a chronic hazard area, and states that populated areas should be decontaminated to essentially zero levels whenever possible.
- 05Pu-239 has a half life of 24,360 years and Pu-238 a half life of 89 years, with Pu-238 about 270 times more active.
- 06In flue tests where plutonium was oxidized at 500 C to 850 C, within the range of petroleum fires, about 2 percent of the sample was liberated as aerosol, all of it in the respirable range.
From the original
It has been prepared with the hope that a general background knowledge of plutonium and its hazards will result in better DOD operations and an enlightened personnel force.
Source: U.S. Department of Energy, OpenNet declassified document archive, OSTI ID 16389161, document number DNA 3272T. The summary is written from the document’s own text. Old scans can be hard to read, so check the original for anything you plan to cite.