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BACKGROUND INFORMATION RELATED TO DRAFT 

ADMINISTRATIVE EXEMPTIONS FOR CERTAIN RADON RELEASES 

In response to the proposed rule to adjust radionuclide reportable 

quantities (RQs), EPA received many comments expressing concern that more than 

an RQ of radon would be released commonly from certain facilities. These 

facilities include a variety of mineral extraction and processing plants, many 

of which produce large volumes of low activity wastes that are stored on-site 

(e.g., gypsum piles at phosphate fertilizer plants). In response to these 

comments, EPA is considering exempting administratively certain radon releases 

from the RQ reporting requirements. Each adminisCraCive exemption would have 

to be supported with evidence as to why the government would never want to be 

notified of the radon release. 

This paper summarizes background information on radon releases from 

certain facilicies or accivicies that could be exempted from the RQ reporting 

requirements. It describes, where applicable, how these radon releases are 

being handled under other regulatory programs. The paper also presents 

preliminary information on che hazards associated wich che radon releases. 

This background informacion is inCended Co help the Radionuclide RQ Workgroup 

decide whether to exempt the radon releases from the reporting requirements of 

CERCLA section 103. 

Phosphate Fertilizer Plants. Including Phosphogypsum Piles 

The production of fertilizer uses approximately 80 percent of the 

phosphate rock mined in the U.S. Concentrations of natural uranium and its 

decay products (including radium, the immediate parent of radon) in phosphate 

deposits range from ten to one hundred times the concentration of uranium in 

other natural rocks and soils (49 FR 43914, October 31, 1984). 

On April 6, 1983 and October 31, 1984, EPA's Office of Radiation Programs 

announced in the Federal Register (48 FR 15078 and 49 FR 43906) that good 

reasons existed to exclude radionuclide emissions from fertilizer plants from 

regulation under the National Emission Standards for Hazardous Air PolluCanCs 

(NESHAPs). The reasons ciCed for Chis exclusion were as follows: 

o Fercilizer planCs release radionuclides inco the air 

primarily in the form of dust particles. Particulate 

emissions from new or modified fertilizer plants are 

controlled by new source performance standards issued 

under Section 111 of the Clean Air Act. Existing 

fertilizer planCs are regulaced for particulate 

emissions by State implementation plans as required 

by the Clean Air Act. These particulate emission 

standards and conCrols limic effectively radionuclide 

releases. 

o The risks to nearby individuals and the total 

population risks due to radionuclide emissions from 

phosphate fertilizer plants are insignificant. The 

technical analysis supporting this conclusion is 
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presented in a related Background Information 

Document.1/ 

The Federal Register notices and supporting Background Document, however, 

do not address releases of radon, which is a gas rather than a particulate. 

Also, these sources analyze only stack emissions as opposed to releases from 

phosphogypsum piles (fertilizer plant waste material that is stored on-site). 

In fact, the October 31, 1984 notice (49 FR 43914) states that: 

EPA did not propose radionuclide standards for this source 

because it believed that such wastes would be more 

appropriately regulated under the Resource Conservation 

and Recovery Act. After considering all comments, EPA is 

reevaluating the need for radionuclide standards for this 

source. Preliminary risk estimates indicaCe ChaC 

individual lifecime risks from exposure Co air emissions 

from these piles may be as high as eight in ten thousand. 

Population risks may be on the order of one fatal cancer 

per year. The Agency will continue its examination of the 

need for a standard for this source category. 

Since this notice, EPA has completed studies on phosphate rock 

beneficiation tailings and has determined that regulation of these tailings as 

hazardous wasCe under RCRA is noc needed (51 FR 36233, OcCober 9, 1986). A 

similar study of phosphogypsum reportedly is almost complete. Based on a 

conversacion with James Hardin of the Office of Radiation Programs, however, 

a final determination with respect to air emission standards for 

phosphogypsum piles has noc been made. 

Independent calculaCions show ChaC radon releases from phosphogypsum 

piles probably approach and may exceed a radon emission sCandard for remedial 

accions aC inacCive uranium mill Callings piles. The radon exhalacion rate 

from ground contaminated with radium-226 (the parent of radon-222) can be 

calculated using the following equation:2/ 

\ 0.5 

J - ApE (AD) 

where; 

J - radon exhalation rate in pCi/cm2-sec; 

A - concencracion of radium-226 in ground (pCi/gm); 

p -j bulk densiCy of Che soil, typically about 1.7 gm/cm3; 

1/ EPA, Radionuclides: Background Information Document for Final Rules. 

Volume II. Office of Radiation Programs, EPA 520/1-84-022-2, October 1984. 

2/ Nuclear Regulatory Commission, Final Generic Environmental Impact 

Statement on Uranium Milling. NUREG-0706, September 1980. 
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E - the fraction of radon that escapes from a particle, 

typically taken as 0.2 for uranium mill tailings; 

*\- the radon-222 decay constant (2.1 x 10-6 sec-1); and 

D - the diffusion coefficient for radon in soil 

(cm2/sec). 

According to the National Council on Radiation Protection (NCRP),1/ the 

radium-226 concentration in gypsum waste ranges generally between 30 and 40 

pCi/gm. Values for the diffusion coefficient (D) in the literaCure vary over 

four orders of magniCude, depending on Che soil moisture and other factors. 

According to a study of Florida phosphogypsum stockpiles,4/ the moisture 

content of phosphogypsum ranges from three percent to roughly 18 percent. 

Using these moisture content values in an equation for D obtained from a 

Department of Energy document,.5/ values for D for phosphogypsum might vary 

between 5x10-2 cm2/sec and 1x10-3 cm2/sec. Plugging all of these values into 

the above equation for the radon release rate, initial estimates of radon 

.releases from phosphogypsum piles range from 5 pCi/m2-sec to 40 pCi/m2-sec. 

In comparison, EPA has issued under 40 CFR Part 192 a radon emission standard 

of 20 pCi/m2-sec for uranium mill tailings piles. EPA has stated thaC chis 

emission standard provides "excellent protection of public health, safety, and 

the environment" (the lung cancer risk to the most exposed individual would be 

reduced to a few chances in a thousand) (48 FR 598-599). 

In conclusion, insufficient evidence has been obtained to conclude that 

the government would never wane Co be noCified of radon releases from 

phosphace fercilizer planCs and phosphogypsum piles. Previous regulacory 

decisions examined Co date are inconclusive with respect to this issue and 

preliminary calculations suggest that radon releases from some phosphogypsum 

piles may be a concern. EPA is continuing to gather and evaluate additional 

information Co help reach a decision on how chese radon releases should be 

handled under Che RQ rulemaking. 

1/ NCRP Reporc No. 77, Exposures from the Uranium Series With Emphasis 

on Radon and Its Daughters. 1984. 

4/ Alexander May and John Sweeney, Evaluation of Radium and Toxic 

Element Leaching Characteristics of Florida Phosphogypsum Stockples. Bureau of 

Mines Report of Investigations No. RI 8776, U.S. Department of the Interior, 

1983. 

5/ Department of Energy, Pathway Analysis and Radiation-Dose Estimates 

for Radioactive Residues at Formerly Utilized MED/AEC Sites. ORO-832, Dist. 

Category UC-70A, March 1983.