MATERIAL SUPPLEMENTAL TO STATEMENT OF SEPTEMBER 11, 1958, On the basis of an informal arrangement made with the Division of Raw Materials of the Atomic Energy Commission in June 1959 the Bureau of Mines is conducting inspections of uranium mines operated on land leased from the Atomic Energy Commission. All active mines have been inspected and re-inspections have been started. The enclosed paper on Bureau of Mines Inspection of Uranium Mines on Indian Land presents the current status of that activity. The Joint Committee on Atomic Energy's investigation of Federal-State relationships in regulating radiation hazards, as described in your letter of August 25, 1958, to the Director, Bureau of Mines, should provide interesting and timely results. Health and safety measures to be followed by Bureau of Mines personnel Under provisions of Chapter 395.2, Bureau Station or Unit Radiation The health-safety measures set forth in Chapter 395.2, and Bureau of COPY COPY The Bureau is at present conducting a program in cooperation with industry, State agencies, and the Public Health Service to establish criteria for the protection of uranium and thorium miners against underground radiation hazards. In this regard, the Bureau has inspected uranium mines on Indian Lands and those on Public Domain leased from the Geological Survey to determine the adequacy of ventilation and dust control procedures to insure safe working conditions. The States of Colorado, Utah, and New Mexico--major producers of uranium ore--have promulgated laws to protect operators of mines where radioactivity may be present in the workings. The Bureau of Mines recommends, in the interest of mine safety, that all parties concerned with mining familiarize themselves with these State laws and comply with them. Excerpts from the regulations of the three States are found in Bureau of Mines Information Circular 7834, Engineering Control of Health and Safety Hazards in Uranium Mines, which you will find enclosed. Sincerely yours, (Sgd.) Royce A. Hardy Assistant Secretary of the Interior Hon. Clinton P. Anderson Enclosures 2 ADDRESS BY JAMES WESTFIELD, ASSISTANT DIRECTOR--HEALTH AND SAFETY, BUREAU OF MINES, DEPARTMENT OF THE INTERIOR, SCHEDULED FOR PRESENTATION TO 63RD NATIONAL WESTERN MINING AND ENERGY CONFERENCE, SPONSORED BY COLORADO MINING ASSOCIATION, DENVER CHAMBER OF COMMERCE, UNITED URANIUM INDUSTRY COMMITTEE, AND AFFILIATED GROUPS, DENVER, COLORADO, APRIL 21, 1960 BUREAU OF MINES INSPECTION OF URANIUM MINES ON INDIAN LAND One of the advisory responsibilities of the Bureau of Mines is the inspection of mines on Indian lands. In conducting these inspections the Bureau evaluates all conditions that are related to safety of operations, but since this paper is directed mainly to discussion of possible hazards from radiation in uranium mining on Indian lands, detailed comments on over-all safety problems will not be presented. In common with other agencies involved with occupational health, the Bureau of Mines is aware that the presence of radon and its radioactive decay products in the air of uramium mines may constitute a potential hazard to the health of mine workers. Concern over this possible hazard has stemmed largely from reported experience in certain European mining areas where ores containing radioactive materials are extracted. The situations in the United States and Europe are not exactly parallel, however, because the European ore bodies contain a variety of elements, some of which are potentially harmful, that are not associated with the uranium ores now produced in the United States. Thus far the Bureau of Mines has inspected 95 uranium mines on Indian lands. Fifty-nine of these mines were underground operations, and 36 were opencut. Some of these mines have been worked out since the earlier inspections, and now are abandoned. Frequency of inspections by the Bureau was increased during 1958 and 1959, and the discussion today relates mainly to inspections conducted during the past two years. URANIUM MINES ON INDIAN LANDS IN ARIZONA AND NEW MEXICO The typical underground uranium mine on Indian land is a small operation with intermittent production and variable ore quality. On the average, the ore is rather low-grude. This tends to decrease possible hazards from radon and other radioactive decay products of the parent uranium. Only 7 of the active underground mines inspected during 1959 employed 10 or more men. Mining is by open-stope methods with irregular pillars, and, occasionally, rock-bolt ground support. Most of the shaft mines have only one manway opening and employ boreholes from the surface to assist ventilation. About half the operations rely solely on natural ventilation. Most of the opencut mines are in small deposits in Coconino County, Arizona, in the vicinity of Cameron. Because of their proximity to each other and their rather short productive lives, these small operations lend themselves to profitable mining by being worked in groups. By using mobile equipment and coordinated work procedures with small operating forces, drilling and blasting may be conducted at one pit while broken ore is being loaded at another. Overhead costs may be kept down by central location of shops, explosives magazines, and other necessary facilities. During 1959, the Bureau of Mines inspected 60 uranium mines on Indian lands in Arizona and New Mexico. Thirty-three of these mines were opencut operations employing a total of 438 men, and 27 were underground mines employing 210 men, of whom 102 worked underground. Four of the underground mines were visited for final inspections before abandonment. Production from these 60 mines in 1958 was 1.4 million tons of uranium ores, or about 27 percent of the total uranium production in the United States that year. About nine-tenths of the production from mines on Indian lands came from one opencut operation in New Mexico; the remaining output divided about equally between underground and opencut operations. SURVEYS BY BUREAU OF MINES Evaluation of Radiation Levels Radon gas and its solid decay products, some of which emit alpha particles capable of causing undesirable radiation exposure if inhaled, are of chief concern in assessing radiation levels in uranium mines. These materials are sampled and measured during Bureau of Mines inspections by methods recommended by the United States Public Health Service. Radon gas also may be measured to provide a basis for estimating requirements for safe ventilation. In addition to uranium, these ores contain all the other elements that result from radioactive decay, some of which emit gamma rays, which are similar to X-rays and could cause undesirable total-body radiation exposure. For this reason, an inspection includes an overall measurement of existing gamma radiation, although to date no excessive levels of gamma radiation have been observed. Interpretation of Radiation Measurements The United States Public Health Service/ has suggested a "working level" for estimating possible hazards from the decay products of radon in the air of uranium mines. This guide is intended as an interim engineering yardstick until time permits development of more information on the subject. Since emission of alpha particles by some of the decay products of radon presents the most serious hazard, the suggested working level is expressed as 1.3 x 105 million electron volts of potential alpha energy per liter of air. This level is equivalent to a total concentration of 300 micromicrocuries of the decay products of radon per liter of air. In evaluating radiation resulting from the presence of radon decay products in uranium mines, and in recommending control measures--principally increased ventilation to reduce possible hazards from this source--the Bureau of Mines uses 1/ Holaday, D. A., Rushing, D. E., Coleman, R. D., Woolrich, P. F., Kusnetz, H. L., and Bale, W. F., Control of Radon and Daughters in Uranium Mines and Calculations on Biologic Effects. U. S. Public Health Service Publication No. 494, 1957, 81 pp. 2/ Work cited. Footnote 1. |