Disposal of Radioactive Material by Release Into Sanitary Sewer Systems; Withdrawal of Advance Notice of Proposed Rulemaking, 68350-68368 [05-22432]

Agencies

• NUCLEAR REGULATORY COMMISSION

[Federal Register Volume 70, Number 217 (Thursday, November 10, 2005)]
[Proposed Rules]
[Pages 68350-68368]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-22432]


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Proposed Rules
                                                Federal Register
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This section of the FEDERAL REGISTER contains notices to the public of 
the proposed issuance of rules and regulations. The purpose of these 
notices is to give interested persons an opportunity to participate in 
the rule making prior to the adoption of the final rules.

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Federal Register / Vol. 70, No. 217 / Thursday, November 10, 2005 / 
Proposed Rules

[[Page 68350]]



NUCLEAR REGULATORY COMMISSION

10 CFR Part 20

[RIN 3150-AE90]


Disposal of Radioactive Material by Release Into Sanitary Sewer 
Systems; Withdrawal of Advance Notice of Proposed Rulemaking

AGENCY: Nuclear Regulatory Commission.

ACTION: Advance notice of proposed rulemaking: Withdrawal.

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SUMMARY: The Nuclear Regulatory Commission (NRC) is withdrawing an 
advance notice of proposed rulemaking (ANPR) that presented possible 
changes to the regulations governing the release of radionuclides from 
licensed nuclear facilities into sanitary sewer systems. Changes were 
proposed to account for the potential for radionuclide concentration 
during some types of wastewater treatment processes. NRC is withdrawing 
this advance notice of proposed rulemaking because it has determined 
that there are no widespread public health and safety concerns due to 
potential radiation exposures associated with the handling, beneficial 
use, and disposal of sewage sludge containing radioactive materials. 
This notice of withdrawal acknowledges public comments sent in response 
to the ANPR.

FOR FURTHER INFORMATION CONTACT: A. Christianne Ridge, Office of 
Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory 
Commission, Washington, DC 20555-0001, telephone (301) 415-5673, e-mail 
acr1@nrc.gov.

SUPPLEMENTARY INFORMATION: On February 25, 1994 (59 FR 9146), NRC 
published an ANPR to seek information to determine whether an amendment 
to its regulations governing the release of radionuclides from licensed 
nuclear facilities into sanitary sewer systems was needed. NRC was 
considering revising the approach to limiting these releases because of 
the potential effects of newly-developed sewage treatment technologies 
on radionuclide reconcentration during wastewater treatment. The 
Commission requested advice and recommendations on several proposals 
and asked related questions regarding whether and in what way the 
regulations governing the release of radionuclides from licensed 
nuclear facilities into sanitary sewer systems should be changed. NRC 
received seventy-four comment letters in response to the ANPR. The 
comment period expired on May 26, 1994.
    Because there were concerns raised on the broader issue of long-
term effects of releases of radioactive materials into sanitary sewer 
systems, action on the ANPR was deferred until studies were conducted 
regarding potential radioactive contamination in sewage sludge. Since 
that time, NRC participated in the Interagency Steering Committee of 
Radiation Standards (ISCORS) and co-chaired, with the Environmental 
Protection Agency (EPA), the Sewage Sludge Subcommittee to facilitate a 
systematic and thorough study of the potential concerns related to 
radionuclides in sewage sludge and to obtain data to support a 
technical basis for a regulatory decision.

Regulatory Framework Relevant to the Release of Radioactive Material 
Into Sanitary Sewers

    NRC regulations governing the release of licensed material into 
sanitary sewer systems can be found in 10 CFR 20.2003. This regulation 
was published in the Federal Register (56 FR 23360; May 21, 1991) as 
part of an overall revision of NRC standards for protection against 
radiation. Licensees were required to implement this regulation by 
January 1, 1993. As part of the 1991 revision of 10 CFR Part 20 
regulations, NRC removed the broad provision that allowed the release 
of non-biological insoluble materials into sanitary sewers because of 
the potential for this material to reconcentrate in sewers, publicly 
owned treatment works (POTWs), and sewage sludge. The current NRC 
regulations require that any licensed material discharged into a 
sanitary sewer system must be readily soluble in water or be readily 
dispersible biological material. In addition, the concentration limits 
for radionuclides released into a sanitary sewer system, listed in 
Table 3 of the Appendix B to Part 20, were reduced by a factor of 10 as 
part of an overall reduction in effluent release limits. In addition to 
the limits in 10 CFR 20.2003, NRC recommends that licensees should 
maintain doses as low as is reasonably achievable (ALARA) by setting 
goals for effluent concentrations and quantities to be only a modest 
fraction (10 to 20 percent) of their allowable limits, as described in 
NRC Regulatory Guide 8.37, ``ALARA Levels for Effluents from Materials 
Facilities,'' dated July 1993. NRC also conducts periodic inspections 
to ensure that licensees are in compliance with NRC regulations.

Surveys, Studies, and Reports Relevant to the Release of Radioactive 
Material Into Sanitary Sewers

    In May 1992, NRC issued the results of a scoping study in NUREG/CR-
5814, ``Evaluation of Exposure Pathways to Man from Disposal of 
Radioactive Materials into Sanitary Sewer Systems,'' which evaluated 
the potential radiological doses to POTW workers and members of the 
public from exposure to radionuclides in sewage sludge. The first part 
of the analysis estimated the potential doses to workers for five cases 
in which radioactive materials were detected at POTWs (Tonawanda, NY; 
Grand Island, NY; Royersford, PA; Oak Ridge, TN; and Washington, DC). 
Doses from the case studies were estimated to range from less than 10 
microsieverts per year ([mu]Sv/yr) (1 millirem per year (mrem/yr)) to 
930 [mu]Sv/yr (93 mrem/yr) for members of the public, using a 
deterministic scenario analysis and the reported radionuclide 
concentrations and/or discharges. The second part of the study 
estimated the maximum radiation exposures to POTW workers and others 
who could be affected by low levels of man-made radioactivity in 
wastewater. The quantities of radionuclides released into the sewer 
systems were assumed to be the maximum allowed under NRC regulations at 
the time. Estimates of the hypothetical, maximum exposures to workers 
ranged from zero to a dose roughly equal to the dose individuals 
receive from natural background radiation.
    In May 1994, the U.S. General Accounting Office (GAO, now U.S. 
Government Accountability Office) issued a report, GAO/RCED-94-133,

[[Page 68351]]

``Nuclear Regulation: Action Needed to Control Radioactive 
Contamination at Sewage Treatment Plants'', that described nine cases 
where contamination was found in sewage sludge or ash or in wastewater 
collection systems. GAO concluded that the full extent of contamination 
nationwide was unknown. GAO also concluded that the ``problem of 
radioactive contamination of sludge and ash in the reported cases was 
the result, in large part, of NRC's regulation, which was incorrectly 
based on the assumption that radioactive materials would flow through 
treatment systems and not concentrate.'' In June 1994, a joint U.S. 
House of Representatives and Senate hearing (June 21, 1994; S. Hrg. 
103-1034) was held to officially release and address questions raised 
in the GAO report. At the hearing, NRC and EPA agreed to cooperate to 
develop guidance for POTWs and to collect more data on the 
concentration of radioactive materials in samples of sewage sludge and 
ash from POTWs nationwide.
    Between 1994 and 1997, Federal, State, and industry studies were 
conducted to assess reconcentration of radioactive materials that are 
released into sanitary sewer systems. In December 1994, NRC published 
NUREG/CR-6289, ``Reconcentration of Radioactive Material Released into 
Sanitary Sewers in Accordance with 10 CFR Part 20.'' A review of the 
literature demonstrated that some radioactive materials discharged into 
sanitary sewer systems reconcentrate in sewage sludge. However, the 
report concluded that the available data were not sufficient to assess 
the adequacy of the requirements in 10 CFR 20.2003 in preventing 
occurrences of radionuclide reconcentration in sewage sludge at levels 
which present significant risk to the public; nor is the available data 
sufficient to suggest strategies for changing the requirements.
    In 1996, the Association of Metropolitan Sewerage Agencies (AMSA) 
conducted a limited survey of reconcentration of radioactivity in 
sewage sludge and ash samples from some of its member POTWs. Samples 
were obtained from 55 wastewater treatment plants in 17 States. The 
most significant sources of radioactivity were potassium and radium 
isotopes, which are Naturally Occurring Radioactive Materials (NORM). 
In December 1997, the Washington State Department of Health issued a 
report WDOH/320-013, ``The Presence of Radionuclides in Sewage Sludge 
and Their Effect on Human Health,'' that was based on sludge samples 
taken at six POTWs in the State. The report concluded that that there 
was no indication that radioactive material in sewage sludge in the 
State of Washington poses a health risk.
    The Interagency Steering Committee on Radiation Standards (ISCORS) 
was formed in 1995, to address inconsistencies, gaps, and overlaps in 
current radiation protection standards. In 1996, the Sewage Sludge 
Subcommittee of ISCORS was formed to coordinate efforts to address the 
recommendations in the 1994 GAO Report. Between 1998 and 2000, the EPA 
and NRC (through the ISCORS) jointly conducted a voluntary survey of 
POTW sewage sludge and ash to help assess the potential need for NRC 
and/or EPA regulatory decisions. Sludge and ash samples were analyzed 
from 313 POTWs, some of which had greater potential to receive releases 
of radionuclides from NRC and Agreement State licensees, and some of 
which were located in areas of the country with higher concentrations 
of NORM. In November 2003, the results of the survey were published in 
a final report, NUREG-1775, ``ISCORS Assessment of Radioactivity in 
Sewage Sludge: Radiological Survey Results and Analysis.'' No 
widespread or nationwide public health concern was identified by the 
survey and no excessive concentrations of radioactivity were observed 
in sludge or ash. The results indicated that the majority of samples 
with elevated radioactivity had elevated concentrations of NORM, such 
as radium, and did not have elevated concentrations of radionuclides 
from manmade sources.
    In February, 2005, the Sewage Sludge Subcommittee published a 
report, NUREG-1783, ``ISCORS Assessment of Radioactivity in Sewage 
Sludge: Modeling to Assess Radiation Doses.'' This report contains dose 
modeling results for seven different sewage sludge management scenarios 
for POTW workers and members of the public. Results of the dose models 
and survey results indicated that there is no widespread concern to 
public health and safety from potential radiation exposures associated 
with the handling, beneficial use, and disposal of sewage sludge 
containing radioactive materials, including NORM.
    In February, 2005, the Sewage Sludge Subcommittee also published a 
report, ``ISCORS Assessment of Radioactivity in Sewage Sludge: 
Recommendations on Management of Radioactive Materials in Sewage Sludge 
and Ash at Publicly Owned Treatment Works;'' (EPA 832-R-03-002B; ISCORS 
Technical Report 2004-04). This report provides guidance to: (1) Alert 
POTW operators, as well as State and Federal regulators, to the 
possibility that radioactive materials may concentrate in sewage sludge 
and incinerator ash; (2) inform POTW operators how to determine whether 
there are elevated levels of radioactive materials in the POTW's sludge 
or ash; and (3) assist POTW operators in identifying actions for 
reducing potential radiation exposure from sewage and ash.

Reasons for Withdrawing the ANPR

    The results of the survey and dose modeling work conducted by the 
ISCORS Sewage Sludge Subcommittee regarding radioactive materials in 
sewage sludge and ash provide a technical basis for withdrawing the 
ANPR. The survey demonstrated that the most significant levels of 
radioactive materials in POTWs are attributable to NORM. The dose 
modeling work indicated that, in general, the doses from licensed 
materials in sewage sludge present a sufficiently low health and safety 
risk to POTW workers and to the public under the current regulatory 
structure. Therefore, it is not necessary to modify the current 
restrictions regarding the release of radioactive materials into 
sanitary sewers (10 CFR 20.2003) as discussed in the ANPR. In addition, 
public comments indicated that several of the options discussed in the 
ANPR would be costly to implement and may not be consistent with 
efforts to maintain doses ALARA. For these reasons, NRC is withdrawing 
the ANPR.

Public Comments on the Potential Changes to 10 CFR Part 20

    In the ANPR, NRC invited comment on the following aspects of the 
regulation of release of radionuclides into sanitary sewers: The form 
of materials suitable for disposal, the limits on the total 
radioactivity of materials that can be released by a licensee into 
sanitary sewers in a year, also called the ``total quantity limit,'' 
the types of limits applied, and the exemption for medical patient 
excreta. The following is a summary of those comments and NRC 
responses.

(1) Form of Material for Disposal

    The May 21, 1991, final rule (10 CFR 20.2003) allows soluble and 
readily dispersible biological material to be released but prohibits 
the release of any non-biological insoluble material. Because NRC 
recognized that new technologies for wastewater treatment, such as ion-
exchange and some types of biological treatment, can reconcentrate 
radionuclides, NRC invited comments regarding whether and how 
regulations should account for the effects of different wastewater 
treatment

[[Page 68352]]

technologies on radionuclide reconcentration. NRC also invited comments 
regarding the potential impacts that additional restrictions on the 
form of materials allowable for release into sanitary sewers would have 
on licensee operations. Public comments regarding the adequacy of the 
current restrictions also were received.
    Comment: Nine commenters, including representatives of the New York 
State Energy Office, New York State Department of Environmental 
Conservation, AMSA, and the Department of Energy (DOE), expressed the 
view that the regulations should be reevaluated because of new sewage 
treatment technologies or should account for the effects of new 
technologies used to treat sewage or sewage sludge. One commenter 
suggested that NRC limits should account for a variety of POTW-specific 
factors, including sludge handling processes, and sludge disposal 
methods, and restrictions on the POTW's treated water discharge. 
Another commenter suggested NRC should take new sewage treatment 
technologies into account only if the results of NUREG/CR-6289, which 
was incomplete at the time the comment was made, indicated that new 
sewage treatment technologies had the potential to cause significant 
reconcentration of radionuclides in sewage sludge. Two commenters 
recommended NRC develop technology-specific reconcentration factors to 
help POTW operators to design appropriate pretreatment plans. A 
representative of DOE suggested NRC should expect that advances in the 
sewage treatment process would result in increasing concentration of 
radionuclides in sewage sludge. Two commenters recommended NRC 
regulations account for synergistic health effects of radiation and 
pollutants in wastewater, and one suggested NRC evaluate the 
synergistic effects of radiation and the chlorine and fluoride used in 
drinking water treatment.
    Response: NRC acknowledges the commenters' support for regulations 
that would account for the reconcentration of radionuclides by 
wastewater treatment processes. However, the regulations will not be 
changed because the ANPR is being withdrawn for the reasons previously 
explained.
    Comment: Four commenters expressed the view that NRC regulations 
should not take sewage treatment technologies into account. Reasons 
included uncertainty that new technologies will be implemented and a 
lack of information about the effects of the new technologies on 
radionuclide reconcentration. A representative of the State of Illinois 
Department of Nuclear Safety suggested NRC should keep informed of 
technological developments, but should not implement additional 
restrictions without significant evidence that the current restrictions 
are not adequate. Two commenters suggested that, rather than revising 
Sec.  20.2003 to account for new treatment technologies, NRC should 
consider placing additional restrictions on individual licensees to 
provide the necessary protection to the receiving POTWs in unusual 
cases where the number of licensees, size of the sewage treatment plant 
or nature of the technology used at the treatment plant may cause doses 
above 100 mrem/yr. One commenter stated that it is unnecessary for NRC 
regulations to account for sewage sludge treatment technologies because 
local POTWs have the authority and mandate to account for these 
technologies by developing industrial water discharge permits pursuant 
to 40 CFR 403.5(c)(1).
    Response: NRC acknowledges the commenters' opposition to the 
proposed rule change, which supports NRC's decision to withdraw the 
ANPR. With respect to the comment that POTWs have the authority and 
mandate to impose limits on radioactive materials released into 
sanitary sewers, NRC notes that, as described in Section 4.7 of the 
ISCORS recommendations on management of radioactive materials in sewage 
sludge and ash (EPA 832-R-03-002B), POTWs may not have the same 
authority to regulate radioactive material as they do to regulate other 
materials released into sanitary sewers.
    Comment: Eight commenters expressed the view that NRC regulations 
should account for the fact that several licensees may discharge to the 
same POTW, and, of those, five expressed the view that the regulations 
should also take the capacity of the POTW into account. Five commenters 
stated that restrictions on the release of nonradioactive pollutants 
established under EPA's National Pollutant Discharge Elimination System 
(NPDES) account for the capacity of the receiving POTW, the wastewater 
treatment systems used, and the number of industrial users discharging 
to a POTW, and suggested any new regulations governing the release of 
radioactive materials into sanitary sewers should take these factors 
into account. A representative of DOE expressed the view that changes 
to the regulations to account for multiple dischargers should be 
considered but may not be necessary because sanitary systems serving 
multiple licensees would probably be large systems in which the 
licensees' effluent would be diluted by many other inputs to the sewer 
system. One commenter suggested that, if limits on the total amount of 
radioactivity individual POTWs could receive were developed, any cases 
in which the limits are being exceeded by licensees that were already 
discharging sewage into the sewer system before the limits were 
developed should be handled on a case-by-case basis.
    Response: NRC acknowledges the commenters' support for regulations 
that would account for the capacity of individual POTWs and the number 
of licensees discharging to a single POTW. However, the proposed change 
will not be implemented for the reasons previously explained.
    Comment: Twenty-seven commenters were opposed to additional 
restrictions on the forms of material suitable for release into 
sanitary sewers. Twenty-one stated that the potential for significant 
reconcentration of radionuclides during wastewater treatment probably 
had been addressed by the May 21, 1991 changes to Part 20 (56 FR 23360) 
that restricted the forms of materials that could be released into 
sanitary sewers and lowered concentration limits. Another commenter 
expressed the view that it was unclear whether contamination described 
in the case studies discussed in the ANPR occurred because of 
violations of the existing regulations, and also that it would be 
inappropriate for NRC to respond to individual violations of regulatory 
requirements by making changes to the regulations for all licensees. 
Representatives of six licensees indicated that additional restrictions 
on the forms of material appropriate for disposal would impose a 
significant burden on their operations. Commenters listed the costs of 
building new storage facilities, analyzing samples of waste to 
determine whether insoluble radionuclides were present, and 
establishing new collection, handling, and disposal procedures as well 
as retraining of personnel as expenses that would be incurred if 
additional restrictions were imposed. In addition, three commenters 
expressed the concern that further restricting the forms of material 
appropriate for disposal in a sanitary sewer would not be consistent 
with NRC's policy that doses should be maintained ALARA because the 
additional waste handling that would be required would cause doses to 
workers that would not be justified based on the minimal dose to 
members of the public or POTW workers that might be avoided.
    Response: NRC acknowledges the commenters' remarks, which support

[[Page 68353]]

the withdrawal of the ANPR. However, the NRC staff notes the need to 
analyze samples of waste to determine if the waste contains insoluble 
radionuclides should not impose an additional burden because the 
restriction on releasing insoluble, non-biological wastes was already 
in place when the comment was made.
    Comment: Twenty-three commenters encouraged NRC to continue to 
allow release of readily soluble wastes that met the quantity and 
concentration release criteria in 10 CFR Part 20. Twenty-one of those 
commenters indicated that they were unaware of any significant problems 
caused by the disposal of soluble radioactive material in sewer 
systems. Three commenters stated that they were not aware of any 
mechanisms that would reconcentrate the wastes typical of biomedical 
research in sewage sludge, and two of these stated that the activity 
levels were sufficiently low that reconcentration, even if it did 
occur, would not cause a significant dose.
    Response: NRC acknowledges the commenters' support for the 
continuation of the current regulations which allow certain 
concentration and quantities of readily soluble radioactive material 
into sanitary sewers.
    Comment: Two commenters suggested that NRC should change the 
regulation to re-establish disposal of dispersible non-biological 
materials. One commenter suggested disposal of non-biological 
dispersible materials should be allowed for materials that have half-
lives of less than 100 days or are below the concentrations listed in 
10 CFR Part 20 Appendix C.
    Response: NRC acknowledges the commenters' suggestion that release 
of non-biological dispersible material into sanitary sewers be allowed. 
NRC understands that reconcentration of a radionuclide in sewage sludge 
can be limited by its half life. However, NRC has chosen not to change 
the regulation governing the release of radioactive material into 
sanitary sewers for the reasons previously explained.
    Comment: Six commenters, including a representative of DOE, noted 
that the chemical form of materials released into the sewer can change, 
and that materials that are soluble when released may precipitate or 
sorb to solid particles in the sewer or treatment plant. A 
representative of the New York State Department of Environmental 
Conservation suggested NRC study not only the effect of new 
technologies on radionuclide solubilities, but also how the solubility 
of radioactive materials change in sanitary sewers. A representative of 
DOE noted that precipitation and sorption could cause risks to 
individuals who work in POTWs, work in close contact with sewers, or 
who incinerate or use wastewater treatment sludge. In addition, the 
commenter remarked that, while it appeared to be reasonable to limit 
sewer releases to soluble and dispersible biological materials, NRC 
should realize that licensees could release insoluble or nondispersible 
materials to sewer systems inadvertently. One commenter expressed the 
view that NRC regulations should account not only for the form of 
material when released, but the form it was likely to take after being 
discharged.
    Three commenters expressed the view that, because the form of a 
material discharged is likely to change when it reaches the sewer or 
POTW, the modification to 10 CFR 20 that eliminated disposal for non-
biological ``readily-dispersible'' materials may not have removed the 
chance that radionuclides could reconcentrate in wastewater treatment 
sludge. Two commenters remarked that reconcentration of radionuclides 
probably would continue, in part because POTWs are designed to remove 
dissolved contaminants from wastewater. However, both commenters 
expressed the opinion that reconcentration is not necessarily a problem 
if the dose any individual is expected to receive from exposure to 
sewers, sewage, or sludge is low.
    Response: NRC understands that materials that are released into the 
sewer in a soluble form can precipitate or sorb to solid materials in 
sewers or POTWs, as discussed in NUREG/CR-6289. Most of the commenters' 
concerns about the potential risk to POTW workers are addressed in the 
ISCORS dose modeling report (NUREG-1783), as previously explained. 
Although the ISCORS dose analysis (NUREG-1783) does not include an 
analysis of doses to workers that come into contact with sewers, those 
doses are expected to be limited because of the limited amount of time 
a worker would spend in close contact with a sewer and because of the 
relatively low doses predicted for most scenarios that involve contact 
with sewage sludge.
    NRC acknowledges the concern that licensees may inadvertently 
dispose of insoluble non-biological material. NRC also acknowledges the 
suggestion that the regulations should account for changes in the form 
of materials that are likely to occur in sewers and POTWs and the 
concern about the efficacy of the 1991 revisions. For the reasons 
previously explained, NRC has decided not to change the regulations 
governing the release of radioactive material into sanitary sewers. 
However, NRC staff notes that, in addition to restrictions on form, NRC 
also has imposed annual limits in 10 CFR 20.2003(a)(4) on the total 
amount of radioactivity that can be released into sanitary sewers to 
limit the potential for reconcentration of radioactive material in 
sanitary sewers, sewage sludge, and sludge ash.
    Comment: Five commenters supported additional restrictions on the 
form of materials that can be released into sanitary sewers. One 
commenter expressed the view that the practice, used by some medical 
research laboratories, of releasing pureed tissue samples to the 
sanitary sewer was distasteful. Another commenter expressed the opinion 
that NRC should impose any requirement that would minimize the amount 
of radioactivity in the environment.
    Response: NRC acknowledges the commenters' support for additional 
restrictions on the forms of material suitable for release into 
sanitary sewers but is not changing the regulations because it believes 
the current approach is sufficiently protective, as previously 
explained.
    Comment: Three commenters requested clarification regarding the 
distinction between soluble and readily dispersible materials. One 
requested that an information notice be produced to address materials 
used in the biotech industry. Another commenter expressed the concern 
that it would be difficult to demonstrate compliance with the 
restriction that only soluble and readily-dispersible biological 
materials be released into sanitary sewers if colloids that flow 
through filters and resins are classified as non-biological dispersible 
material. The commenter proposed an operational procedure to 
distinguish between soluble and readily dispersible materials. A 
representative of the New York State Department of Environmental 
Conservation noted that traces of insoluble radioactive material could 
be released into sewers with soluble materials, and requested that NRC 
establish a lower limit of detection for insoluble material.
    Response: NRC acknowledges the commenters' request for additional 
guidance on how licensees should demonstrate the solubility of 
radioactive material released to sanitary sewers. Although NRC does not 
have plans to provide additional guidance on this issue, the staff 
notes that, as discussed in NRC Information Notice 94-007, licensees 
are free to develop alternative methods of demonstrating the solubility 
of materials they wish to release into sanitary sewers and to submit 
these

[[Page 68354]]

procedures to NRC for evaluation on a case-by-case basis.

(2) Total Quantity of Material

    In the May 21, 1991 final rule, NRC did not change the total 
quantity limits, which allow a licensee to release 185 gigabecquerel 
(GBq) (5 curies (Ci)) of H-3, 37 GBq (1 Ci) of C-14, and 37 GBq (1Ci) 
of all other radioactive materials combined into sanitary sewers each 
year. The use of total quantity limits has been a long-standing 
requirement and was originally included in the rule (10 CFR 
20.2003(a)(4)) to address concerns regarding the possibility for 
reconcentration of radionuclides. In the ANPR, NRC invited comments 
about the alternative approach of limiting the annual release of each 
radionuclide individually. NRC also invited comments about the current 
total quantity limits and the potential impacts that additional 
restrictions on the annual releases into sanitary sewers would have on 
licensees.
    Prior to publishing the ANPR, NRC received a petition for 
rulemaking to amend 10 CFR 20.303 (superseded by Sec.  20.2003) and 
Sec.  20.305 (superseded by Sec.  20.2004) from the Northeast Ohio 
Regional Sewer District (PRM-20-22). A notice of receipt of the 
petition was published in the Federal Register (58 FR 54071; October 
20, 1993). The petitioner requested that NRC amend its regulations to 
require that all licensees provide at least 24 hours advance notice to 
the appropriate POTW before releasing radioactive material to the 
sanitary sewer system. The petitioner also requested that NRC exempt 
materials that enter the sanitary waste stream from the requirements 
regarding Commission approval for incineration under NRC's current 
regulations. NRC solicited comments on the petition in the ANPR. The 
denial of the petition was noticed in the Federal Register on January 
27, 2005 (70 FR 3898).
    Comment: Six comments received in response to the ANPR supported 
annual total quantity limits. Two commenters, including a 
representative of DOE, suggested total quantity limits should be 
retained because they help prevent reconcentration of radionuclides in 
sewage sludge and two supported the total quantity limits because they 
are easy for licensees and regulators to understand and implement. Two 
commenters, including the representative of DOE, suggested it may be 
worthwhile for NRC to evaluate whether the regulation could be 
optimized by changing the annual release limits for some radionuclides. 
A representative of the Illinois Department of Nuclear Safety expressed 
the opinion that the relatively low doses calculated for the case 
studies described in the ANPR and predicted for other scenarios in 
NUREG/CR-5814 indicated that reconcentration of radionuclides in sewage 
sludge could be addressed on a case-by-case basis rather than by 
changing the total quantity limits in Sec.  20.2003.
    Response: NRC acknowledges support for the current approach of 
using annual limits on the total quantity of radioactive material that 
can be released into sanitary sewers by a licensee. In accord with the 
commenters' suggestion, NRC performed a study to evaluate the 
reconcentration of various radiounuclides in POTWs, the results of 
which are discussed in NUREG/CR-6289.
    Comment: A representative of the City of Oak Ridge made positive 
and negative statements about NRC annual total quantity limits. The 
commenter stated that both concentration and total quantity limits were 
necessary to ensure protection of workers and to ensure that 
traditional methods of sludge disposal remain acceptable. However, the 
commenter also expressed the view that the current values of the total 
quantity limits are too high and stated that disposal of 37 GBq (1 Ci) 
of Co-60 annually to the Oak Ridge POTW would result in unacceptably 
high concentrations of Co-60 in the POTW's sludge, especially if the 
material was released during a relatively short time period. The 
commenter also expressed the opinion that the total quantity limits are 
inappropriate for low specific activity radionuclides because of the 
large mass of the radionuclide that could be discharged. As an example, 
the commenter stated that release of 37 GBq (1 Ci) of U-238 to the 
city's POTW in a year would result in a mass concentration of uranium 
of more than 0.05 percent in the POTW's sludge, making the sludge 
licensable source material. In addition to these comments, the 
commenter suggested that, because the mean retention time of sludge at 
a POTW typically is one month or less, a monthly discharge limit would 
be more appropriate than an annual limit.
    Response: NRC acknowledges the commenter's concern about the 
release of Co-60 to a POTW and the suggestion that quantity limits 
should be implemented on a monthly, rather than an annual, basis. The 
staff notes that the 1991 revision to 10 CFR Part 20 that eliminated 
the discharge of insoluble non-dispersible radioactive material into 
sanitary sewers was implemented to reduce the possibility of 
significant contamination of sewage sludge with insoluble 
radionuclides, such as Co-60. NRC has decided not to change the 
regulations governing sewer release of radioactive material for the 
reasons previously explained. NRC acknowledges the commenter's concern 
about the applicability of the total quantity limit to low specific 
activity radionuclides. However, NRC does not agree that the 
accumulation of large masses of low-specific activity radionuclides in 
POTWs is likely to be problematic. In addition POTWs have some 
authority to impose limits on the release of material into sanitary 
sewers when the purpose of the limits is not radiation protection, as 
discussed in Section 4.7 of the ISCORS recommendations on management of 
radioactive materials in sewage sludge and ash (EPA 832-R-03-002B).
    Comment: Twenty-three commenters described concerns about the 
current approach of limiting the total amount of radioactivity a 
licensee may release into a sanitary sewer system. Nineteen commenters 
expressed the opinion that it is not appropriate to apply the same 
total quantity limit to large and small facilities that discharge 
different amounts of sewage and therefore dilute radioactive materials 
to different extents. Another commenter stated that NRC should not 
attempt to impose total quantity limits on large facilities. Seventeen 
commenters expressed the view that NRC should consider relaxing the 
total quantity limits because of the new restriction on the form of 
material and lower release concentration limits implemented in the 1991 
revision to 10 CFR Part 20. The commenters expressed the opinion that 
adherence to the new form and concentration limits may eliminate the 
need for total quantity limits. Three commenters suggested that, 
instead of limiting the total quantity of radioactivity a licensee 
could dispose of into a sewer, NRC should focus on the radionuclides 
and chemical forms of radionuclides that reconcentrate in POTWs to a 
significant extent. One commenter expressed the concern that a person 
could dispose of 37 GBq (1 Ci) of Cs-137 within a month while remaining 
in compliance with the current concentration and total quantity limits. 
Another commenter suggested concentration limits are sufficient and are 
superior to total quantity limits because concentration limits account 
for the total volume of water a licensee releases to the sanitary sewer 
system. The commenter noted that, although the nominal purpose of the 
total quantity limits is to eliminate reconcentration, the total 
quantity limits do not appear to prevent reconcentration, as evidenced 
by the case studies described in the

[[Page 68355]]

ANPR. The commenter suggested reconcentration could be avoided by 
reducing the allowable concentrations of those radionuclides that have 
shown a tendency to reconcentrate in sewage sludge.
    Response: NRC acknowledges the comment about the application of the 
same total quantity limit to large and small facilities, but believes 
that the system is appropriate. Because the total quantity limit is 
designed to reduce the potential for reconcentration of radionuclides 
at POTWs, an appropriate total quantity limit is more dependent on the 
volume of sewage received by a POTW than it is on the volume of a 
licensee's effluent.
    NRC acknowledges the comment that total quantity limits should be 
relaxed or eliminated, but does not agree that the limits on form and 
concentration eliminate the need for annual quantity limits. As 
discussed in NUREG/CR-6289, the form of radionuclides can change upon 
entering a sewer or POTW because of sorption and precipitation. NRC 
also acknowledges the concern that total quantity limits did not 
prevent the cases of contamination discussed in the ANPR. NRC believes 
that limiting both the form and total quantity of material released 
into sanitary sewers is the best way to limit the potential for 
significant reconcentration of radionuclides released by licensees into 
sanitary sewers.
    NRC acknowledges the commenters' suggestion that, instead of 
imposing total quantity limits, it should focus on those radionuclides 
that have been shown to reconcentrate in sewers or sewage sludge. NRC 
also acknowledges the commenter's concern about the discharge of Cs-137 
but believes the current approach to be sufficiently protective for the 
reasons previously explained.
    Comment: One commenter expressed the view that additional 
limitations on the release of H-3 and C-14 into sanitary sewers would 
not produce any public health benefit because any dose an individual 
received from sewer-disposed H-3 and C-14 would be negligible in 
comparison to the dose the individual would receive from naturally-
produced H-3 and C-14.
    Response: NRC acknowledges the commenter's view that additional 
restrictions on the quantities of H-3 and C-14 are unnecessary. The 
comment supports the withdrawal of the ANPR and the current total 
quantity limits which allow the annual release of 185 GBq (5 Ci) of H-3 
and 37 GBq (1 Ci) of C-14 in addition to the release of 37 GBq (1 Ci) 
of all other radionuclides combined.
    Comment: Eight licensees expressed the view that additional 
restrictions on the total quantity of radioactive material that could 
be released into sanitary sewers annually would have a severe negative 
impact on their facilities' operations. Representatives of a biomedical 
company, a university, and the National Institutes of Health (NIH) 
noted that a reduction in the total quantity limits would impose a 
significant financial burden on organizations involved in biotechnical 
research, development, or medical practice, especially if the limits 
were reduced to a point that liquid wastes would need to be solidified 
and disposed of as low level waste (LLW). The representative of NIH 
estimated that solidification and disposal of liquid wastes as LLW 
would cost NIH 2.8 million dollars annually, as of 1994. Two commenters 
remarked that companies would bear the additional expense of acquiring 
or building storage facilities or acquiring treatment technologies to 
remove radioactivity from liquid waste streams. One commenter noted 
that LLW disposal of many of the materials currently released into 
sanitary sewer systems would be a particularly unnecessary expense and 
inefficient use of LLW landfill space because, in many cases, the 
material would decay to negligible quantities before it reached the LLW 
landfill.
    Five commenters associated with medical research facilities or 
companies that produce radiopharmaceuticals suggested additional 
restrictions on the total quantity of radioactive material that could 
be released into sanitary sewers annually could harm public health and 
safety by causing companies to limit biomedical research and 
development efforts. One of these commenters stated that the amount of 
radioactivity released into sanitary sewers in association with medical 
research was insignificant as compared to the amount of radioactivity 
released to sewers in patient excreta and concluded that release of 
radioactive materials associated with biomedical research should be 
allowed as long as the exemption for patient excreta is continued. Two 
commenters expressed the opinion that additional restrictions on the 
total quantity of radioactivity a licensee could release into sanitary 
sewers annually would not be consistent with efforts to maintain doses 
ALARA because workers would be exposed to radioactive material while 
processing liquid waste to make it suitable for LLW disposal.
    A representative of a company that offers health physics services 
stated that, for most of its clients who want to release radioactive 
material into sanitary sewers, the most limiting factor is the annual 
total quantity limits. A representative of the University of California 
expressed concern that the numerical limits in 10 CFR 20.2003 would be 
lowered, although the university typically releases only 11.1 Gbq (0.2 
Ci) of radioactivity into sanitary sewers each year.
    Response: NRC acknowledges the commenter's concerns about the 
potential impacts of additional restrictions on the total quantity of 
radioactive material that a licensee can release to sewers annually. As 
previously explained, the additional restrictions discussed in the ANPR 
will not be implemented.
    Comment: A representative of AMSA stated that, although the 
organization understands that lowering total quantity limits could 
impose financial burdens on licensees, additional restrictions are 
appropriate if they are needed to prevent contamination of sewage 
sludge.
    Response: NRC acknowledges the commenter's statement, but has 
decided not to change the total quantity limits because it believes the 
current approach is sufficiently protective for the reasons previously 
explained.
    Comment: Twenty-one letters received in response to the ANPR 
included comments on the Northeast Ohio Regional Sewer District's 
request for NRC to amend its regulations to require that all licensees 
provide at least 24 hours advance notice to the appropriate POTW before 
releasing radioactive material into a sanitary sewer system. Six of the 
twenty-one commenters supported a requirement for licensees to provide 
the sewage treatment plant with some type of reporting on the 
radioactive materials released into the sanitary sewer system. These 
commenters supported a wide range of reporting requirements, including 
the petitioner's request for a 24-hour advance notification before 
licensees release radioactive material, monthly or annual discharge 
reports, reports of releases that could be a threat to the POTW workers 
or the environment, or notification of large accidental releases. One 
commenter suggested licensees should analyze effluent samples and 
include the results in discharge reports. A representative of AMSA 
stated that advance notice of releases is necessary so that POTW 
operators can ensure worker health and safety and make appropriate 
decisions about sludge disposal and reuse.
    Fifteen of the twenty-one commenters did not support such a 
requirement for licensees to provide at least 24-hour

[[Page 68356]]

advance notice to the appropriate sewage treatment plant before 
releasing radioactive material into a sanitary sewer system. Several 
commenters said that a 24-hour advance notification would result in an 
unnecessary regulatory burden without providing additional protection 
against radiation or dose reduction. These commenters expressed the 
view that the existing regulations for discharges of licensed material 
maintain doses at or below the existing dose limits for members of the 
public and if licensees meet the ALARA goals, the 24-hour advance 
notification would be unnecessary. Several commenters noted that such 
notification would be impractical because most releases are continuous 
and involve very small quantities of radioactive material. For example, 
discharges from hospitals and medical facilities would change daily 
depending on the number of patients treated and types of treatment 
used.
    Several commenters also noted that there could be large cost 
implications and regulatory burdens associated with such notification. 
In addition, commenters were concerned that data about releases of 
radioactive material could be misinterpreted if release reports were 
received and interpreted by sewage treatment plant personnel rather 
than radiation safety specialists. Several commenters stated that such 
an NRC requirement for licensees to provide a 24-hour advance 
notification was unnecessary because local municipalities have 
authority over their local sewer district, already have requirements to 
follow the Clean Water Act, and may establish a pretreatment program 
for wastewater acceptance. One commenter noted that the usefulness of a 
24-hour advance notification should be assessed after the new limits 
for sewer discharges are in place.
    Response: NRC has determined that a requirement for advance 
notification of each release of radioactive material to a sanitary 
sewer would impose an unnecessary regulatory burden on licensees 
without a commensurate health and safety benefit. Additional reasons 
for the denial of the petition are discussed in the Federal Register 
notice published on January 27, 2005 (70 FR 3898).
    Comment: Six comment letters received in response to the ANPR 
included comments on the Northeast Ohio Regional Sewer District's 
request that NRC exempt materials that enter the sanitary waste stream 
from the requirement for NRC approval prior to treatment or disposal of 
licensed material by incineration. Four commenters supported such an 
amendment because, given the radioisotopes and activities involved, the 
pathways for human exposure from radioactive wastes seem no more or 
less significant if the wastes are dispersed into water or air. These 
commenters suggested that, if release into a sanitary sewer system is 
to be considered disposal, the limits should be set so that no further 
regulation of the radioactive material is needed after release. One 
commenter did not support such an amendment and expressed the view that 
it would only serve to provide an open-ended system for radioactive 
material to pass into the environment and to the public without 
limitation or characterization.
    Response: NRC approval to incinerating waste is required to ensure 
that NRC may evaluate the potential impact to the public health and 
safety and the environment on a case-by-case and site-specific basis. 
Hazards associated with incineration of sewage sludge will depend on 
the specific characteristic of the sludge and the radionuclides that 
may be present. Additional reasons for the denial of the petition are 
discussed in the Federal Register notice published on January 27, 2005 
(70 FR 3898).

(3) Type of Limits

    The present approach to limiting releases of radioactive material 
into sanitary sewers is to specify limits on both the monthly average 
concentration of each radionuclide in a licensee's sewage and the total 
quantity of radioactive matter that a licensee can release annually. 
Table 3, Appendix B, of 10 CFR Part 20 lists the allowable monthly 
average concentration of each radionuclide in a licensee's release to 
sewers. Allowable concentrations are based upon a calculated dose of 5 
mSv/yr (500 mrem/yr) due to ingestion of 2 liters per day of a 
licensee's effluent into the sanitary sewer.
    In the ANPR, NRC invited comments on this regulatory approach. 
Specifically, NRC invited comment as to whether it should continue to 
base concentration limits on the assumption that an individual would 
drink 2 liters of the effluent from a licensee's facility each day, and 
whether exposure at other locations, such as at a POTW, should be 
considered in developing release limits. In addition, NRC invited 
comments about how other exposure scenarios, such as exposure to 
radionuclides in contaminated sludge, should be accounted for. NRC also 
invited comments as to whether it should establish limits in terms of 
dose instead of limits on the quantity and concentrations of 
radioactive material discharged. Included with the responses to these 
inquiries were several comments about monitoring, enforcement actions, 
and regulatory authority to set limits on releases of radioactive 
material into sanitary sewers that have been addressed with the General 
Comments.
    Comment: Twenty-three commenters supported the current modeling 
approach of assuming that an individual ingests 2 liters of water taken 
from the licensee's outfall to the sewer system each day. Nineteen of 
these commenters, representing hospitals, biomedical laboratories, and 
universities, noted that this assumption is conservative and easy for 
licensees to understand. A representative of DOE noted that the 
approach appears to be bounding, and has been ``largely successful as a 
regulatory measure''. The commenter also expressed the view that, 
because this type of consumption is not expected to be chronic, it is 
appropriate to base concentration limits on a calculated annual dose of 
500 mrem instead of 100 mrem. One commenter did not specifically 
address the assumption that an individual would drink 2 liters of a 
licensee's discharge each day, but did support the use of a licensee's 
sewer outfall as an appropriate exposure location. Two commenters 
expressed the view that the modeling assumption was appropriate because 
individuals, including children, could drink or otherwise be exposed to 
water directly downstream of a sewer outfall. Another commenter that 
supported the current assumption expressed the view that modeling 
exposure at a licensee's outfall to a sewer system is consistent with 
modeling exposure at a licensee's fence line, as is done in other NRC 
assessments, and that considering a downstream location would be 
inconsistent with modeling exposure to the maximally exposed 
individual.
    Response: NRC acknowledges support for the current modeling 
assumption. The staff notes that several commenters appeared to believe 
that the concentration limits were based on the assumption that an 
individual would consume 2 liters of sewage from a POTW outfall, rather 
than 2 liters of a licensee's effluent into the sewer system, each day. 
Staff notes that the assumption that an individual would consume a 
licensee's effluent is more conservative than the assumption that an 
individual would consume POTW effluent because the concentration of 
radionuclides in POTW effluent will have been diluted with effluent 
from all of the other residential and industrial dischargers to the 
POTW.

[[Page 68357]]

    Comment: Three commenters expressed concern that the concentration 
limits are based on an annual dose of 5 mSv (500 mrem) and stated that 
the concentration limits should be based on an annual dose of no more 
than 1 mSv (100 mrem), in accord with the 10 CFR 20.1301 limit on doses 
to members of the general public from licensed activities. One 
commenter expressed the view that the 1 mSv (100 mrem) annual public 
dose limit should be lowered. Two commenters expressed the view that 
the dose from ingesting a licensee's effluent should be included in the 
1 mSv (100 mrem) TEDE annual public dose limit rather than being 
calculated separately and excluded from the 10 CFR 20.1301 limit. 
Another expressed the view that, if any activity were to be permitted 
to be discharged into sanitary sewers, the limiting dose for exposure 
to sewage sludge should be no greater than the dose limit for low level 
radioactive waste.
    Response: NRC acknowledges the commenters' concern about the 
hypothetical dose used as the basis for the concentration limits. As 
discussed in the ANPR, the NRC staff believes the concentration limits 
based on an annual dose of 5 mSv (500 mrem) are reasonable because it 
is unlikely that an individual would have access to and would consume 
water at the point at which a licensee discharges water into the 
sanitary sewer and because dilution from additional discharges into the 
sewer is likely to reduce the expected dose to well below the 1 mSv 
(100 mrem) annual dose limit.
    NRC also acknowledges the commenters' suggestion that the dose from 
consuming effluent released into the sanitary sewer be included in the 
TEDE from other licensee operations. However, in the case of sewer 
discharge, the point of exposure is expected to be remote from the 
licensee's facility. Because individuals that could be exposed to a 
facility's effluent are different individuals than those that live 
closest to the facility, it would be unrealistic to include the dose 
from exposure to a licensed facility's effluent in the total dose from 
all of the facility's activities. The staff notes that comments 
regarding the appropriate value of the annual dose limit for members of 
the public from licensed activities specified in 10 CFR 20.1301 are 
beyond the scope of this rulemaking.
    Comment: Ten commenters did not support the use of the current 
modeling approach of assuming that an individual ingests 2 liters of 
water taken from a licensee's sewer outfall each day. Almost all of 
these commenters expressed the view that the assumption is unrealistic. 
One commenter expressed the view that, while the assumption that an 
individual ingests 2 liters of water taken from a licensee's sewer 
outfall each day is a reasonably conservative basis for concentration 
limits, the assumption may not be a basis for total quantity limits 
because it would over-emphasize the potential impact of short-lived 
radionuclides.
    Response: NRC acknowledges the commenters' opposition to the 
current modeling approach. However, it will be retained because the 
ANPR is being withdrawn for the reasons previously explained. With 
respect to the comment about the basis for total quantity limits, the 
staff notes that the assumption that an individual would consume a 
licensee's effluent is used as the basis of the concentration limits 
but is not used as the basis of the total quantity limits.
    Comment: Ten commenters suggested alternate locations that NRC 
should consider when developing restrictions on the release radioactive 
materials into sanitary sewer systems. Of these, five suggested NRC 
consider the dose to a person ingesting water once it has reached or is 
leaving a POTW rather than at the licensee's sewer outfall. Three 
commenters suggested NRC consider locations downstream of a POTW that 
would be likely to be locations from which a municipality would extract 
drinking water, while one suggested doses in the nearest residential 
area should be considered. Another commenter suggested realistic models 
would incorporate a factor of at least one million between the point of 
discharge and a receptor locations, and suggested that, if NRC used a 
more realistic dose model, it would become clear that additional 
release restrictions are unnecessary. One commenter suggested that, in 
considering potential doses to members of the public, NRC should 
consider that sludge could be sent to a landfill, applied to 
agricultural land, or made into compost for sale to the public.
    Five commenters, including representatives of POTWs and DOE, 
recommended NRC consider doses to sanitation workers and two commenters 
suggested NRC consider doses to workers that come into contact with 
sewage collection systems as well as POTW workers. One commenter noted 
the importance of matching exposure locations to appropriate pathways 
and suggested external radiation by gamma emitters may be an important 
pathway for POTW workers, whereas ingestion of beta emitters would be 
expected to be more important at a downstream drinking water source. 
Five commenters suggested NRC consider that the careful treatment given 
to sewage and sludge because of the other hazards it presents should 
limit doses to sanitary system workers. One commenter added that NRC 
regulations also should prevent contamination of sewers, POTWs, 
receiving waters, and sludge and ash disposal sites. Another commenter 
suggested NRC consider potential exposures to all POTW residuals, 
including sludge, screenings, grit, and ash. The commenter also pointed 
out that sewer pipes may leak and suggested NRC consider the potential 
for groundwater contamination.
    Response: The alternate locations that the commenters suggested 
should be considered in dose models will not be used as a basis for a 
revision to the regulations because the ANPR is being withdrawn for the 
reasons previously explained. However, the NRC staff notes that several 
of the modeling scenarios suggested by the commenters, including sludge 
handling by POTW workers, sludge incineration, and exposure to land-
applied sewage sludge, were considered in the ISCORS dose modeling 
project (NUREG-1783).
    Comment: Six commenters, including representatives of POTWs and the 
New York State Department of Environmental Conservation, suggested 
that, in addition to protecting the general public and sanitation 
workers, NRC regulations should ensure that POTWs can continue to use 
traditional forms of use or disposal of biosolids (sewage sludge). One 
commenter noted that events that have not resulted in significant 
worker exposure have prevented POTWs from using or disposing of sewage 
sludge.
    Response: Additional restrictions on the release of radioactive 
material into sanitary sewers will not be implemented for the reasons 
previously discussed. Section 7.2 of the ISCORS recommendations on 
management of radioactive materials in sewage sludge and ash (EPA 832-
R-03-002B) provides guidance to assist POTW operators in reducing 
sources of radiation entering their treatment facilities.
    Comment: Four commenters made suggestions about ways to account for 
complex exposure scenarios, such as exposure to contaminated sewage 
sludge. One commenter suggested that a variety of scenarios should be 
evaluated and that the scenario resulting in the highest dose should be 
used to establish limits on releases of radionuclides to sewers. 
Another commenter expressed the opinion that dose models should reflect 
limitations on access that are imposed to protect individuals from 
other health risks associated with sewage and sewage sludge. One

[[Page 68358]]

commenter suggested no model could adequately represent complex 
exposure scenarios because dose modeling was not sufficiently well 
developed.
    Response: The approaches the commenters suggested will not be used 
as a basis for new restrictions on the release of radioactive material 
into sanitary sewers because the ANPR is being withdrawn for the 
reasons previously explained. NRC staff acknowledge the commenter's 
statement about the capabilities of dose modeling.
    Comment: Of the fourteen commenters that addressed dose limits, 
seven supported implementation of dose limits. One commenter expressed 
the view that dose limits are preferable to limits on concentration and 
quantity alone because dose limits are easier to relate to risk. The 
commenter suggested the assumptions used to evaluate compliance with 
dose limits should be realistic. The commenter also suggested the use 
of a tiered approach, in which simple bounding assumptions are first 
used to evaluate compliance, and more complex models and more site-
specific data are used only if the simple bounding model does not 
demonstrate compliance. Another commenter suggested that, if the 
appropriate models were developed, releases into sanitary sewers should 
be controlled under the requirements of 10 CFR 20.1302 and ALARA 
guidelines just as other facility effluents are. The commenter also 
noted that the potential doses calculated in NUREG/CR-5814 indicate 
that the current regulations governing the release of radionuclides 
into sanitary sewers are more restrictive than other NRC dose limits on 
facility effluents. Two commenters expressed the view that dose limits 
should be adopted only if the current limits were found not to be 
protective of the public or POTW workers. Four commenters agreed with 
the proposal in the ANPR that, if dose limits were adopted, NRC should 
publish a regulatory guide that included concentration and total 
quantity guidelines to facilitate compliance. One commenter asked if 
licensees would have a choice of complying with the dose limit or with 
the concentration and quantity guidelines published in a Regulatory 
Guide. Two commenters advocated dose limits, but expressed the view 
that the dose limits should be based on measured radionuclide 
concentrations from samples taken from sewer outfalls and intakes or on 
readings from dosimeters placed at POTWs rather than on concentrations 
calculated based on assumptions about releases to and dilution in 
sanitary sewers.
    Response: NRC acknowledges the commenters' support for sewer 
release restrictions to be expressed as limits on dose rather than 
activity. NRC also acknowledges the commenters' suggestion that 
compliance with dose limits be made based on sample measurements. 
However, these options will not be implemented because the ANPR is 
being withdrawn for the reasons previously explained. No response is 
required to the commenter's question about compliance with dose limits 
because the ANPR is being withdrawn.
    Comment: Of the fourteen commenters that addressed dose limits, six 
commenters opposed dose limits, and a representative of the New York 
State Department of Environmental Conservation noted potential problems 
with implementing dose limits but suggested NRC study the option. 
Almost all of the commenters that opposed dose limits commented on the 
uncertainty of assumptions about exposure pathways and the relative 
complexity of implementing dose limits as compared to concentration and 
quantity limits. Three commenters predicted dose limits would require 
more regulatory oversight because NRC would need to review each 
licensee's dose model. One commenter expressed the concern that dose 
limits could make it necessary for licensees to require prior approval 
for releases of radioactive material into sanitary sewers. One 
commenter supported the current limits but suggested that, if dose 
limits were adopted, the dose limit should be 500 mrem/yr, realistic 
modeling assumptions should be made, and the modeling assumptions to be 
used in compliance calculations should be clearly defined. Another 
commenter advocated the use of limits expressed in ``verifiable units 
of measure'' rather than limits expressed as dose and expressed doubts 
about the capabilities of computer models used to calculate dose. 
Another commenter stated NRC should not limit the dose a patient could 
receive from a prescribed medical procedure.
    Response: NRC acknowledges the commenters' opposition to dose 
limits, which will not be implemented because the ANPR is being 
withdrawn.
    With respect to the commenter's concern that NRC should not limit 
the dose a patient could receive due to a medical procedure prescribed 
by his physician, the NRC staff notes the scope of the ANPR was limited 
to potential doses due to exposure to radioactive material in sewage or 
sludge. In general, NRC regulates the uses of radionuclides in medicine 
as necessary to provide for the radiation safety of