United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 84-94: Reconcentration of Radionuclides Involving Discharges into Sanitary Sewage Systems Permitted Under 10 CFR 20.303

                                                          SSINS No.  6835  
                                                          IN 84-94         

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                   OFFICE OF INSPECTION AND ENFORCEMENT  
                           WASHINGTON, DC 20555  

                             December 21, 1984 

Information Notice No. 84-94:   RECONCENTRATION OF RADIONUCLIDES 
                                   INVOLVING DISCHARGES INTO SANITARY SEWAGE 
                                   SYSTEMS PERMITTED UNDER 10 CFR 20.303 

Addressees: 

All NRC materials licensees other than licensees that use sealed sources 
only. 

Purpose: 

This information notice is provided to alert recipients of a potentially 
significant problem involving reconcentration of radionuclides released to 
sanitary sewage systems. It is expected that recipients will review the 
information for applicability to their facilities and consider actions, if 
appropriate, to preclude a similar problem occurring at their facilities. 
However, suggestions contained in this information notice do not constitute 
NRC requirements; therefore, no specific action or written response is 
required. 

Description of Circumstances: 

Three recent occurrences have pointed out the need to focus attention on the
possible reconcentration of radionuclides that are discharged into sanitary 
sewage systems under the provisions of 10 CFR 20.303. In these occurrences, 
radioactive contamination was found in sewer lines and in the municipal 
sewage treatment facility. 

During a routine radiation survey, Oak Ridge Associated Universities found 
radioactive contamination in the sludge from the sewage treatment facility 
in Oak Ridge, Tennessee. The principal contaminant was cobalt-60 (Co-60). 
The State of Tennessee traced the apparent source of the contamination to a 
State licensee who occasionally discharged a few thousand gallons per day of 
liquid into the sanitary system at concentrations of 66-110 dpm/ml of Co-60.
Although the discharge from the licensee's facility was mixed with 4 to 5 
million gallons of liquid from other sources in the city, concentrations of 
20,000-200,000 dpm/Kg were measured in the sludge from the treatment 
facility. Sludge had been used to fertilize a Department of Energy 
reforested area with the result that radiation levels 2 to 3 times 
background were measured there (about 10 R/hr).  As a result of the 
discovery of the problem, the licensee has installed an improved filtration 
and ion exchange system. 



8412190503 
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                                                       IN 84-94           
                                                       December 21, 1984  
                                                       Page 2 of 3        

In the second occurrence, americium-241 (Am-241) contamination was found in 
ash that remained in an incinerator used as a final treatment step at the 
Tonawanda, New York sewage treatment plant and in ash disposed of at the 
Tonawanda landfill. About 10,000 tons of ash containing about 500 picocuries
per gram of ash has been disposed of at the landfill. About 30 tons of 
contaminated ash currently remain in the sewage treatment plant incinerator 
and in ancillary equipment. 

The contamination resulted from liquid releases made to the sanitary sewage 
system by a New York Agreement State licensee who formerly manufactured 
Am-241 foils at its Tonawanda facility. The licensee has since relocated its
foil manufacturing operation to Mexico. Some decontamination of the 
licensee's Tonawanda facility was undertaken following the move. 

The homes, clothes, or cars of four former licensee employees were found to 
be contaminated. Because of exposure to airborne dust at the sewage 
treatment plant, six plant workers received whole-body counting to examine 
the potential for internal deposition. Two of the six were among 58 plant 
workers who received lung scans. No uptake of Am-241 was detected. Several 
issues remain to be resolved. These involve disposal of the contaminated ash 
at the sewage treatment plant, dealing with contaminated ash disposed to the
landfill before identification of the contamination problem, decontamination
of the sewer lines, and decontamination of the licensee's facility. 

In a third occurrence, Am-241 contamination also was found in sludge at a 
sewage treatment plant in Grand Island, New York. The contamination resulted
from liquid releases made to the sanitary sewage system by another New York 
Agreement State licensee also engaged in the manufacture of AM-241 foils. 
The measured concentration in the sludge was about 100 picocuries per gram 
of sludge dry weight. (For purposes of comparison, if this sludge were 
incinerated, concentrations of about 500 picocuries per gram would result in
the ash produced.) In this case, however, the sludge is disposed directly to
a local sanitary landfill. 

The NRC regulation 10 CFR 20.303 permits discharges of small quantities of 
radionuclides into sanitary sewage systems within the limits specified in 
that section provided that the materials "are readily soluble or dispersible
in water." Licensees who rely on this section have the burden of 
demonstrating that the materials they are discharging are indeed readily 
soluble or dispersible. The term "dispersible" may have caused, introduction
of substances into sanitary sewerage systems that do not qualify as readily 
dispersible, such as liquid scintillation media and ash. Ash is a special 
case, which may or may not be "readily dispersible" depending on its degree 
of comminution and tendency to agglomeration. In order to detect and correct
any reconcentration problems involving NRC licensees, inspectors will pay 
particular attention to the possibility of reconcentration of radionuclides 
during their inspections of licensees who discharge materials into sanitary 
sewage systems. 

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                                                       IN 84-94           
                                                       December 21, 1984  
                                                       Page 3 of 3        

No specific action or written response is required by this information 
notice. If you have any questions about this matter, please contact the 
Regional Administrator of the appropriate NRC regional office, or this 
office. 


                              J. Nelson Grace, Director 
                              Division of Quality Assurance, Safeguards, 
                                and Inspection Programs 
                              Office of Inspection and Enforcement 

Technical Contact:  L. I. Cobb 
                    (301) 492-4935 

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