Regulatory guides are issued to describe and make available to the public such information as methods acceptable to the NRC staff for implementing specific parts of the NRC’s regulations,

techniques used by the staff in evaluating specific problems or postulated accidents, and data needed by the NRC staff in its review of applications for permits and licenses. Regulatory

guides are not substitutes for regulations, and compliance with them is not required. Methods and solutions different from those set out in the guides will be acceptable if they provide a

basis for the findings requisite to the issuance or continuance of a permit or license by the Commission.

This guide was issued after consideration of comments received from the public. Comments and suggestions for improvements in these guides are encouraged at all times, and guides will

be revised, as appropriate, to accommodate comments and to reflect new information or experience. Written comments may be submitted to the Rules and Directives Branch, ADM, U.S.

Nuclear Regulatory Commission, Washington, DC 20555-0001. 

Regulatory guides are issued in ten broad divisions: 1, Power Reactors; 2, Research and Test Reactors; 3, Fuels and Materials Facilities; 4, Environmental and Siting; 5, Materials and Plant

Protection; 6, Products; 7, Transportation; 8, Occupational Health; 9, Antitrust and Financial Review; and 10, General. 

Single copies of regulatory guides (which may be reproduced) may be obtained free of charge by writing the Distribution Services Section, U.S. Nuclear Regulatory Commission,

Washington, DC 20555-0001, or by fax to (301)415-2289, or by email to DISTRIBUTION@NRC.GOV. Electronic copies of this guide and other recently issued guides are available at

NRC’s home page at <WWW.NRC.GOV> through the Electronic Reading Room, Accession Number ML021260630.

U.S. NUCLEAR REGULATORY COMMISSION Revision 1

May 2002

REGULATORY

GUIDE

OFFICE OF NUCLEAR REGULATORY RESEARCH

REGULATORY GUIDE

8.31

(Draft was issued as DG-8027)

INFORMATION RELEVANT TO ENSURING THAT OCCUPATIONAL

RADIATION EXPOSURES AT URANIUM RECOVERY FACILITIES WILL BE

AS LOW AS IS REASONABLY ACHIEVABLE

A. INTRODUCTION

This revision of Regulatory Guide 8.31 has been developed to provide guidance on design criteria

and administrative practices acceptable to the NRC staff for maintaining occupational exposures as low as is

reasonably achievable (ALARA) in uranium recovery (UR) facilities (for example, uranium milling, in situ

leach facilities, ion exchange facilities, heap leach facilities). This guidance can also be applied, in part, to

other types of UR facilities and portions of conversion facilities since some of the processes used in these

facilities are similar to those in UR facilities.

Section 20.1101 of 10 CFR Part 20, "Standards for Protection Against Radiation," states that

licensees must use, to the extent practical, procedures and engineering controls based upon sound radiation

protection principles to achieve occupational doses and doses to members of the public that are as low as is

reasonably achievable. Regulatory Guide 8.10, "Operating Philosophy for Maintaining Occupational

Radiation Exposures As Low As Is Reasonably Achievable" (Ref. 1), sets forth the philosophy and general

management policies and programs that licensees should follow to achieve this objective.
8.31-2

An existing NRC report, NUREG-0706, "Final Generic Environmental Impact Statement

on Uranium Milling" (Ref. 2), also provides detailed information for controlling the radiation

hazard and chemical toxicity of airborne uranium and its daughter products in UR facilities.

This guide is directed toward occupational health protection from radiologic and toxic

hazards from airborne particulates of uranium and its daughters. However, it is also recognized

that UR operation workers will be exposed to external radiation in addition to inhaled particulates. 

Therefore, ensuring protection of operation workers from external radiation hazards is also

addressed.

Specific guidance regarding protection of the public from radiologic and toxic hazards

caused by materials in effluents to unrestricted areas is beyond the scope of this guide. This topic

is mentioned only in connection with actions that influence both occupational exposure and

effluent control. Some of the same controls that have been shown to keep occupational exposures

to airborne uranium and its daughters ALARA also tend to keep releases of these materials from

the UR facility ALARA (see Regulatory Guide 4.14, "Radiological Effluent and Environmental

Monitoring At Uranium Mills" (Ref. 3).

The information collections contained in this regulatory guide are covered by the

requirements of 10 CFR Part 20, which were approved by the Office of Management and Budget,

approval number 3150-0014. The NRC may not conduct or sponsor, and a person is not required

to respond to, a collection of information unless it displays a currently valid OMB control number.

B. DISCUSSION

The principle of maintaining occupational radiation exposures as low as is reasonably

achievable is an extension of an original recommendation of the National Committee on Radiation

Protection (NCRP) (now the National Council on Radiation Protection and Measurements) in its

Report No. 17 (Ref. 4). In this early report, the NCRP introduced the philosophy of assuming that

any radiation exposure may carry some risk and recommended that radiation exposure be kept at a

level “as low as practicable” below the recommended maximum permissible dose equivalent. 

This philosophy is currently referred to as “as low as is reasonably achievable” (ALARA). Similar

recommendations to keep exposures ALARA have been included in NCRP reports (Ref. 3), as

well as in recommendations of the National Academy of Sciences-National Research Council

(Ref. 5), the Federal Radiation Council (Ref. 6), and other independent scientific and professional

organizations (Ref. 7). Therefore, NRC has incorporated this basic radiation protection philosophy

from these recommendations into its regulations and guides.

Regulatory Guide 8.10 (Ref. 1) lists the types of management commitments and radiation

protection programs that would help to achieve the objective of maintaining occupational

exposures ALARA for all specific licensees. This guide provides a detailed supplement of the

basic philosophy of Regulatory Guide 8.10 for uranium recovery licensees.

Regulatory Guide 3.5, “Standard Format and Content of License Applications for Uranium

Mills” (Ref. 8), outlines the information that applicants should include in an application for a
1

 An application and a suggested format for its completion may be obtained from the licensing staff of the Division of Waste

Management, Office of Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, Washington, DC 20555.

2 “Management” is the persons authorized by the licensee of record to make policies and to direct activities of the recovery

facility.

3

 The title "radiation safety officer" is used synonymously with "radiation protection manager" by many licensees and will be

used in this guide to designate the qualified individual who is responsible for developing and supervising the radiation safety

program; other titles are equally acceptable.

8.31-3

uranium mill license. This regulatory guide describes the details of an acceptable radiation

protection and ALARA program that an applicant should describe as recommended in Regulatory

Position 5, “Operations,” of Regulatory Guide 3.5. Also see Regulatory Guide 3.46, “Standard

Format and Content of License Applications, Including Environmental Reports, for In Situ

Uranium Solution Mining” (Ref. 9).

C. REGULATORY POSITION

The principles and practices presented in this guide should be used as guidance in

developing the radiation protection and ALARA program for a UR facility for appropriate sections

of an application1

 for a new or renewal license. The recommendations of this guide are intended to

assist applicants in preparing license applications that are acceptable to the NRC staff and are

consistent with the philosophy of ALARA. Unique features not addressed here will be specifically

reviewed by the NRC licensing staff. This guide could also be used by facilities that concentrate

uranium as a secondary process to control hazards from uranium.

A licensee's program for occupational protection against uranium and its daughters will be

considered consistent with the ALARA philosophy if the UR facility’s operating policies and

programs satisfy the following major principles and practices.

1. ALARA PHILOSOPHY

A major purpose of the occupational radiation protection program at a UR facility is to

maintain radiation exposure ALARA for all employees, contractors, and visitors. The

implementation and effectiveness of a successful ALARA program is the responsibility of

everyone involved in the processing of uranium ores. Responsibilities for conducting a radiation

protection and ALARA program are shared by licensee management,2

 the radiation safety officer

(RSO),3 and all workers in the UR facility.

1.1 Licensee Management

Licensee management is responsible for developing, implementing, and enforcing the

rules, policies, and procedures necessary for an effective radiation protection and ALARA

program to ensure the health and safety of workers and visitors.

Licensee management should provide the following:
8.31-4

1. A strong commitment to and continuing support for the development and

implementation of the radiation protection and ALARA program;

2. Information and policy statements to employees, contractors, and visitors;

3. A periodic management audit program that reviews procedural and operational

efforts to maintain exposures ALARA;

4. Continuing management evaluation of the radiation safety (health physics)

program, its staff, and its allocation of adequate space and money;

5. Appropriate briefings and training in radiation safety, including ALARA concepts

for all uranium employees in the facility and, when appropriate, for contractors and

visitors.

1.2 Radiation Safety Officer

The radiation safety officer (RSO) has primary responsibility for the technical adequacy

and correctness of the radiation protection and ALARA program and has continuing responsibility

for surveillance and supervisory action in the enforcement of the program.

The radiation safety officer should be assigned the following:

1. Major responsibility for the development and administration of the radiation

protection and ALARA program;

2. Sufficient authority to enforce regulations and administrative policies that affect

any aspect of the radiological protection program;

3. Responsibility to review and approve plans for new equipment, process changes, or

changes in operating procedures to ensure that the plans do not adversely affect the

protection program against uranium and its daughters;

4. Adequate equipment and laboratory facilities to monitor relative attainment of the

ALARA objective.

1.3 Uranium Recovery Workers

Because a radiation protection and ALARA program is only as effective as the workers’

adherence to the program, all workers at a UR facility should be responsible for the following:

1. Adhering to all rules, notices, and operating procedures for radiation safety

established by licensee management and the RSO;
8.31-5

2. Reporting promptly to the RSO and licensee management equipment malfunctions

or violations of standard practices or procedures that could result in increased

radiological hazard to any individual;

3. Suggesting improvements for the radiation protection and ALARA program.

2. HEALTH PHYSICS ORGANIZATION AND ADMINISTRATIVE PROCEDURES

2.1 Health Physics Authorities and Responsibilities

The radiation safety officer at a UR site should be responsible for conducting the health

physics program and for assisting the resident manager in ensuring compliance with NRC’s

regulations and the license conditions applicable to worker health protection.

Generally, the RSO should report directly to the resident manager on matters of radiation

safety. The RSO should be directly responsible for supervising the health physics technicians, for

overseeing the day-to-day operation of the health physics program, and for ensuring that records

required by the NRC are maintained. The RSO should have both the responsibility and the

authority, through appropriate line management, to suspend, postpone, or modify any work activity

that is unsafe or potentially a violation of the NRC’s regulations or license conditions, including

the ALARA program. It is recommended that management delegate this responsibility and

authority directly to the RSO. The RSO may have other safety-related duties, such as

responsibility for programs of industrial hygiene and fire safety, but should have no direct

production-related responsibility.

2.2 Operating Procedures

Written standard operating procedures should be established for all activities that involve

handling, processing, or storing radioactive materials. All such procedures should include

consideration of pertinent radiation safety practices. Written procedures should also be established

for such activities as health physics monitoring, sampling, analysis, and instrument calibration. An

up-to-date copy of each written procedure, including accident response and radiological fire

protection plans, should be kept accessible to all employees. All written procedures involving

radioactive material control should be compiled in a manual that allows documentation of each

revision and its date.

To ensure that proper radiation protection principles and techniques are being applied,

written procedures for all activities should be reviewed and approved in writing by the RSO before

being implemented and whenever a change in a procedure is proposed. In addition, the RSO

should review all existing operating procedures at least annually to ensure the procedures do not

violate any newly established radiation protection practices.
4

The term "radiation work permit" is used by many licensees and will be used throughout this guide; other terms such as "special

work permit" are equally acceptable.

8.31-6

For work on nonroutine maintenance jobs when the potential for exposure to radioactive

material exists and for which no standard written operating procedure already exists, a radiation

work permit (RWP)4

 should be used. Such permits should describe the following:

1. The details of the job to be performed,

2. Any precautions necessary to reduce exposure to uranium and its daughters,

3. The radiological monitoring and sampling necessary before, during, and following

completion of the job.

The RSO should indicate by signature the review of each RWP prior to the initiation of

work, and the work should be carried out in strict adherence to the conditions of the RWP. The

RSO should designate a member of the radiation safety office staff or a supervisory member of the

production staff who has received specialized radiation protection training to review and sign

RWPs when the RSO is not available, e.g., during off shifts.

2.3 Surveillance: Audits and Inspections

With sufficient management interest, exposure to hazardous materials is reduced. Frequent

management audit and inspection of worker health protection practices at a UR facility can serve

to provide management with the information necessary to conduct an appropriate ALARA

program.

2.3.1 Daily and Weekly Inspections

The RSO and the facility foreman should conduct a weekly inspection of all facility areas

to observe general radiation control practices and review required changes in procedures and

equipment. The RSO or designated health physics technician should conduct a daily walk-through

(visual) inspection of all work and storage areas of the facility to ensure proper implementation of

good radiation safety procedures, including good housekeeping and cleanup practices that would

minimize unnecessary contamination. Problems observed during all inspections should be noted

in writing in an inspection logbook or other retrievable record format. The entries should be dated,

signed, and maintained on file for at least 1 year. The RSO should review all violations of

radiation safety procedures or other potentially hazardous problems with the resident manager or

other mill employees who have authority to correct the problem. Also, the RSO should review the

daily work-order and shift logs on a regular basis to determine that all jobs and operations with a

potential for exposing personnel to uranium, especially those RWP jobs that would require a

radiation survey and monitoring, were approved in writing by the RSO, the RSO’s staff, or the

RSO’s designee prior to initiation of work.

2.3.2 Monthly Reviews

At least monthly, the RSO should review the results of daily and weekly inspections,

including a review of all monitoring and exposure data for the month. The RSO should provide to
8.31-7

the resident manager and all department heads for their review a written summary of the month’s

significant worker protection activities that contains (1) a summary of the most recent personnel

exposure data, including bioassays and time-weighted calculations, and (2) a summary of all

pertinent radiation survey records.

In addition, the monthly summary report should specifically address any trends or

deviations from the radiation protection and ALARA program, including an evaluation of the

adequacy of the implementation of license conditions regarding radiation protection and ALARA. 

The summary should provide a description of unresolved problems and the proposed corrective

measures. Monthly summary reports should be maintained on file and readily accessible for at

least 5 years.

2.3.3 Radiation Protection and ALARA Program Audit

Licensee management should have annual audits of the radiation protection and ALARA

program performed and written reports on the audits submitted to corporate management. All

members of the audit team should be knowledgeable concerning the radiation protection program

at the UR facility. In addition, one member of the team should be experienced in the operational

aspects of specialized UR facility radiation protection practices. The RSO should accompany the

audit team but should not be a member. 

The audit report should summarize the following data:

1. Employee exposure records (external and time-weighted calculations),

2. Bioassay results,

3. Inspection log entries and summary reports of daily, weekly, and monthly inspections,

4. Documented training program activities,

5. Radiation safety meeting reports,

6. Radiological survey and sampling data,

7. Reports on overexposure of workers submitted to the NRC, Mine Safety and Health

Administration (MSHA), or States,

8. Operating procedures that were reviewed during this time period. 

The report on the annual radiation protection and ALARA audit should specifically discuss

the following:

• Trends in personnel exposures for identifiable categories of workers and types of

operational activities.

• Whether equipment for exposure control is being properly used, maintained, and inspected.
8.31-8

• Recommendations on ways to further reduce personnel exposures from uranium and its

daughters.

2.4 Technical Qualifications of Health Physics Staff

2.4.1 Radiation Safety Officer

The RSO should have the following education, training, and experience:

1. Education: A bachelor's degree in the physical sciences, industrial hygiene, or

engineering from an accredited college or university or an equivalent combination of

training and relevant experience in UR facility radiation protection. Two years of relevant

experience are generally considered equivalent to 1 year of academic study.

2. Health Physics Experience: At least 1 year of work experience relevant to UR operations

in applied health physics, radiation protection, industrial hygiene, or similar work. This

experience should involve actually working with radiation detection and measurement

equipment, not strictly administrative or "desk" work.

3. Specialized Training: At least 4 weeks of specialized classroom training in health physics

specifically applicable to uranium recovery. In addition, the RSO should attend refresher

training on UR facility health physics every 2 years.

4. Specialized Knowledge: A thorough knowledge of the proper application and use of all

health physics equipment used in the UR facility, the chemical and analytical procedures

used for radiological sampling and monitoring, methodologies used to calculate personnel

exposure to uranium and its daughters, and a thorough understanding of the UR process

and equipment used in the facility and how the hazards are generated and controlled during

the UR process.

2.4.2 Health Physics Technicians

In addition to the RSO, there should be a minimum of one full-time health physics

technician at any full-scale operating UR facility. The health physics technician should have one of

the following combinations of education, training, and experience:

1. Education: An associate degree or 2 or more years of study in the physical sciences,

engineering, or a health-related field;

Training: At least a total of 4 weeks of generalized training (up to 2 weeks may be onthe-job training) in radiation health protection applicable to UR facilities;

Experience: One year of work experience using sampling and analytical laboratory

procedures that involve health physics, industrial hygiene, or industrial safety measures to

be applied in a UR facility; or
8.31-9

2. Education: A high school diploma;

Training: A total of at least 3 months of specialized training (up to 1 month may be onthe-job training) in radiation health protection relevant to UR facilities;

Experience: Two years of relevant work experience in applied radiation protection.

The health physics technician should demonstrate a working knowledge of the proper

operation of health physics instruments used in the UR facility, surveying and sampling

techniques, and personnel dosimetry requirements.

2.5 Radiation Safety Training

All new employees should be instructed by means of an established course in the inherent

risks of exposure to radiation and the fundamentals of protection against exposure to uranium and

its daughters before beginning their jobs. Other guidance pertinent to this course is found in

Regulatory Guide 8.13, "Instruction Concerning Prenatal Radiation Exposure" (Ref. 10), and

Regulatory Guide 8.29, "Instruction Concerning Risks from Occupational Radiation Exposure"

(Ref. 11). Additionally, the training should be commensurate with the risks and hazards of the

task. This course of instruction should include the following topics:

1. Fundamentals of Health Protection

• The radiologic and toxic hazards of exposure to uranium and its daughters,

• How uranium and its daughters enter the body (inhalation, ingestion, and

skin penetration),

• Why exposures to uranium and its daughters should be kept ALARA.

2. Personal Hygiene at UR Facilities

• Wearing protective clothing,

• Using respiratory protective equipment correctly,

• Eating, drinking, and smoking only in designated areas,

• Using proper methods for decontamination (i.e., showers).

3. Facility-Provided Protection

• Ventilation systems and effluent controls,

• Cleanliness of the work place,

• Features designed for radiation safety for process equipment,

• Standard operating procedures,

• Security and access control to designated areas,

• Electronic data gathering and storage,

• Automated processes.

4. Health Protection Measurements

• Measurement of airborne radioactive materials,

• Bioassays to detect uranium (urinalysis and in vivo counting),
8.31-10

• Surveys to detect contamination of personnel and equipment,

• Personnel dosimetry.

5. Radiation Protection Regulations

• Regulatory authority of NRC, MSHA, and State,

• Employee rights in 10 CFR Part 19,

• Radiation protection requirements in 10 CFR Part 20.

6. Emergency Procedures.

A written or oral test with questions directly relevant to the principles of radiation safety

and health protection in UR covered in the training course should be given to each worker. The

instructor should review the test results with each worker. The instructor should discuss any

wrong answers to test questions with the worker until the worker understands the correct answer. 

Workers who fail the test should be retested after receiving additional training. These tests and

results should be maintained on file.

Each permanent worker should be provided an abbreviated retraining course annually. 

Documented successful completion of the retraining course should also be maintained on file. 

Retraining should include relevant information that has become available during the past year, a

review of safety problems that have arisen during the year, changes in regulations and license

conditions, exposure trends, and other current topics.

In addition, all new workers, including supervisors, should be given specialized instruction

on the health and radiation safety aspects and on the nonradiological hazards of the specific jobs

they will perform. This instruction should be in the form of individualized on-the-job training. 

Supervisors should be provided additional specialized training on their supervisory responsibilities

in the area of worker radiation protection. Retraining should be conducted annually and

documented. All employees should sign a statement that they received job-specific radiation

safety training. The statement should indicate the dates the training was received and it should be

cosigned by the instructor. Radiation safety matters of concern that arise during plant operation

should be discussed with all workers during regular monthly or bimonthly meetings.

All visitors who have not received training should be escorted by someone properly trained

and knowledgeable about the hazards of the facility. At a minimum, visitors should be instructed

specifically on what they should do to avoid possible radiological and nonradiological hazards in

the areas of the facility they will be visiting.

Contractors that have work assignments in a UR facility should also be given appropriate

training and safety instruction. Contractor workers who will perform work on heavily

contaminated equipment should receive the same training and radiation safety instruction normally

required of all permanent workers. Only job-specific radiation safety instruction is necessary for

contract workers who have previously received full training on prior work assignments at the

facility or have evidence of recent and relevant radiation safety training elsewhere.

2.6 Surveys
8.31-11

The RSO and radiation safety office staff are responsible for performing all routine and

special radiation surveys as required by license conditions and by 10 CFR Part 20. Acceptable

survey methods are specified in the Regulatory Position of Regulatory Guide 8.30, "Health Physics

Surveys in Uranium Recovery Facilities” (Ref. 12).

2.7 Respiratory Protection

The RSO and the radiation safety office staff are responsible for the implementation of a

respiratory protection program, if one is needed. There should be adequate supplies of respiratory

protection devices to enable issuing a device to each individual who enters an airborne

radioactivity area. Additional respiratory protection devices should be located near access points

of airborne radioactivity areas. All airborne radioactivity areas should have controlled access.

Routine physical (medical) evaluation should be required of these individuals who will use

respiratory protective equipment. If the licensee elects to take credit for protection factors, the

respiratory protection program must meet, at a minimum, the requirements of 10 CFR 20.1703 and

should follow the recommendations in Regulatory Guide 8.15, “Acceptable Programs for

Respiratory Protection” (Ref.13), which are supported in NUREG-0041, “Manual of Respiratory

Protection Against Airborne Radioactive Materials” (Ref. 14).

2.8 Bioassay Procedures

The RSO is responsible for implementing a bioassay program. The frequency adopted and

the type of analysis should meet the recommendations in Regulatory Guide 8.22, “Bioassay at

Uranium Mills” (Ref. 15).

3. FACILITY AND EQUIPMENT DESIGN

General considerations for the design of UR facilities and uranium ore processing

equipment should not be based solely on chemical process efficiency, but should also be based on

the relative potential for radiologic and toxic hazards resulting from exposure of personnel to

uranium and its daughters. Major aspects of planning and design that should be considered are

discussed below.

3.1 Space Layout

The facility layout should be designed to maintain employee exposures ALARA while at

the same time ensuring that exposure to other persons is not thereby increased. The facility layout

should provide for:

1. Safe access to process equipment for routine maintenance;

2. Adequate ventilation in all facility areas in which radioactive materials might be

spilled, suspended, or volatilized, (e.g., engineered controls);

3. Isolation of yellowcake drying, packaging, and shipping areas from other accessible

facility areas;
5

The figure 25% is used here to encourage the use of ventilation systems and other process controls in an effort to prevent the

existence of airborne radioactivity areas as defined in 10 CFR 20.1003. According to 10 CFR 20.1701, “The licensee shall use,

to the extent practical, process or other engineering controls (e.g., containment or ventilation) to control the concentrations of

radioactive material in air.”

8.31-12

4. Controlling access to the UR facility and the ability to secure or restrict entry to any

airborne radioactivity areas;

5. Change rooms and shower facilities so that all workers can remove any possible

radioactive contamination before leaving the site;

6. Dispersion control on radioactive materials moving from contamination areas (e.g.,

crushers) to relatively contamination-free areas (e.g., crusher control room);

7. Isolation of facility areas where there is a high potential for the dispersal of uranium

as the result of a fire.

3.2 Access Control

Access to airborne radioactivity areas should be controlled or restricted by the use of

caution signs and procedures, or security locks when permitted by fire protection regulations.

3.3 Ventilation Systems

To the extent practicable, the facility ventilation system should accomplish the following:

1. As a minimum design objective, provide local exhaust ventilation (such as

chemical hoods) or general area ventilation where concentrations of natural

uranium and its daughters may be present in excess of 25% of the values given in

Table 1 of Appendix B to 10 CFR Part 20.5

 The design ventilation rate (air

exchange rate) should be sufficient to maintain airborne concentrations of natural

uranium and its daughters to less than 25% of the Derived Air Concentration

(DAC) given in Table 1 of Appendix B to 10 CFR Part 20.

2. Establish a facility-specific, operational ALARA goal for concentrations of natural

uranium and its daughters at less than 25% of the DAC values given in Table 1 of

Appendix B to 10 CFR Part 20.

3. Design exhaust stacks so that exhausted air will not enter air intakes that service

any other facility areas.

4. Locate exhaust vents in a way that ensures compliance with the requirements of 10

CFR 20.1302, “Compliance with Dose Limits for Individual Members of the

Public,” for effluents to unrestricted areas, as well as ALARA exposure

considerations for the worker, and 40 CFR, "Protection of Environment," Part 190,

"Environmental Radiation Standards for Nuclear Power Operations,” and 10 CFR

20.1101(d) regarding constraint on air emissions of radioactive material. 
6

 Ore is a natural or native matter that may be mined and treated for the extraction of any of its constituents or any other matter

from which source material is extracted in a licensed uranium or thorium mill.

8.31-13

3.4 Fire Control

Because of the potential for loss of control of radioactive material in the event of a fire, a

UR facility should have adequate firefighting equipment and workers should be trained in its

proper use.

Provisions should be made for fire alarms, fire extinguishers, sprinkler systems, fire

hydrants, water tanks, and other general firefighting equipment. Emergency procedures and

training should include immediate fire control as a priority item. Design features should include

automatic fire detection and suppression equipment in high fire-potential areas (e.g., solvent

extraction area). In the event of fire, there should be provision for drainage of solvent to sumps, or

to outside lined ponds. Appropriate caution signs should be posted in areas of fire hazard. Fire

detection systems should be checked weekly. Fire drills should be performed at least

semiannually.

3.5 Laboratory Design Features

Consideration should be given to providing different laboratory facilities for metallurgical

and bioassay analyses, if they are both performed at the UR site. Owing to the sensitivity required

in performing bioassay analyses, provisions should be made to ensure against cross-contamination

of uranium from mill ore samples. Laboratory equipment and surfaces should be constructed of

materials that are easily decontaminated. Laboratory surfaces used for the preparation of bioassay

samples should be decontaminated daily to be as close to background as practicable but less than

200 dpm α/100 cm2

 of total surface contamination. All laboratories in the facility should provide

adequate general ventilation and exhaust fume hoods. Special attention should be directed to the

design of air exhaust systems that service ore sample pulverizing and grinding equipment. The

design of the laboratory should provide for the safe handling, storage, and disposal of radioactive

wastes resulting from sample analyses.

3.6 Ore and Product Storage

UR facility plans should include the following:

1. Provisions for storage of raw ore6

 or other materials to be processed, fine ore bins,

and yellowcake storage in areas so that the material does not cause unnecessary

exposure to the facility’s personnel and so that material is not dispersed by wind

and rain;

2. Adequate space in the yellowcake storage and packaging areas to conduct initial

surveys and spot smear tests of yellowcake packages and to enable decontamination

of drums to avoid transporting a contaminated package through other mill areas;
8.31-14

3. Locations for yellowcake storage and shipping areas that minimize the handling

time required prior to shipment.

3.7 General Equipment Considerations

General features applicable to equipment that will be used for handling, containing, or

contacting uranium and its daughters are as follows:

1. Equipment that contains large volumes of uranium-bearing liquids should be

designed with sumps or dikes to contain the liquids in the event of leaks or spills;

2. Equipment should be designed for optimum ease of carrying out procedures,

especially routine maintenance, to minimize working time where personnel are

exposed to radiation or radioactive material, and to maximize distances of

personnel from the source of radiation with which they are working;

3. Appropriate caution signs and symbols should be provided to meet the

requirements of 10 CFR 20.1901, as discussed in more detail in Revision 1 of

Regulatory Guide 8.30, "Health Physics Surveys in Uranium Recovery Facilities"

(Ref. 12);

4. The use of semiautogenous methods for grinding ore is recommended because of

the significantly reduced generation of airborne dusts.

4. CONTROL OF AIRBORNE URANIUM AND ITS DAUGHTERS

One of the major inhalation hazards associated with UR facilities results from the

resuspension in air of uranium and its daughters. Therefore, properly designed ventilation and

dust control systems are needed to ensure that exposure of workers is maintained ALARA. There

are, in general, four areas that present radiologic and toxic hazards caused by airborne materials at

a typical UR facility. Some of these areas are applicable to mills only and others are applicable to

all types of UR facilities. These areas encompass (1) ore storage, handling, and crushing; (2) ore

grinding, leaching, and concentrating processes; (3) yellowcake precipitation, drying, and

packaging; and (4) miscellaneous mill locations as specified in Regulatory Position 4.4 of this

guide. Appropriate design objectives for ventilation and dust control systems recommended for

each of these generalized facility areas are given below.

4.1 Ore Storage, Handling, and Crushing Areas

Where ore is handled in the open, the objective should be to minimize blowing of dust. 

Water sprinkling systems are recommended for use on ore piles when the ore moisture content is

less than 10%. If ore is crushed and transported in the dry state (i.e., moisture content less than

25%), the use of ventilation systems and dust collectors is recommended. As ore travels along

conveyor belts to the grinder, all drop points should have either hooded dust collectors or dust

suppressant systems, such as sprinklers or foam ejectors. When crushers are used prior to
8.31-15

grinding, it is recommended that a hooded ventilation system be installed over all external

openings to the crusher. The use of wet scrubbers or dust collectors is recommended for

ventilation systems that service ore storage, handling, and crushing areas of the mill to prevent

recirculation of contaminated air.

4.2 Grinding, Leaching, and Concentrating Process Areas

General ventilation systems are recommended to service facility areas where any grinding

method is performed to ensure against the buildup of radon-222 and its daughters and ore dust

normally released in the grinding process. The ventilation rate should be adequate to maintain the

concentrations of radon-222 or its daughters and natural uranium from ore dust to less than 25% of

the DAC value specified in Table 1 of Appendix B to 10 CFR Part 20 as modified by the note to

Appendix B. It is recommended that all leaching and thickening tanks located in enclosed

structures be covered and vented directly to the outside atmosphere. General ventilation systems

for facility areas where leaching and thickening tanks are located should be designed to maintain

natural uranium ore dust concentrations in air at less than 19.0 μg/m3

 of uranium. If the mill is so

designed that the solvent extraction (SX) concentration process equipment is in enclosed

structures, a general ventilation system is recommended and should be designed to maintain the

airborne natural uranium concentration in air to less than 25% of the DAC for natural uranium. 

The use of wet scrubbers on general ventilation systems that service areas of the facility where

grinding and leaching equipment are located is recommended. Scrubbers are not necessary on

ventilation systems that service areas of the facility where the clarification or solvent extraction

equipment is located.

4.3 Precipitation, Drying, and Packaging Areas

General ventilation systems are required and should be designed to maintain the

concentration in air of yellowcake near precipitation tanks, yellowcake thickeners, yellowcake

filters, and yellowcake repulp equipment to less than 25% of the DAC for natural uranium. The

next step of the recovery process involves the drying and packaging of yellowcake. Since the

potential for the release of airborne yellowcake is much greater in dry form, it is recommended that

drying and packaging of yellowcake should be performed in an enclosure that is separated from

other areas of the facility. Also, the drying and packaging enclosure should be maintained under

negative pressure. A separate air suction ring system should also be used at each yellowcake

drumming station; individual suction ring systems need only be operated during periods when the

drum at that location is being filled. The exhausts for the drying and packaging enclosure and the

suction ring should be vented through a wet scrubber. To ensure proper operation, the scrubber

system on the concentrate drying and packaging area should be checked every shift and

documented, or automatic malfunction alarm or interlock systems should be installed. Manometer

readings or operational and instrument checks should be recorded once per shift and subsequently

documented.

4.4 Miscellaneous Locations

Other important areas of the UR facility that have the potential to contain hazardous levels

of uranium and its daughters in air include maintenance shops, metallurgical and bioassay
8.31-16

laboratories, and general laundries, if they exist. Each of the above facility areas should be

serviced by ventilation systems designed to maintain air concentration of natural uranium and its

daughters to less than 25% of the DAC for natural uranium. Wet scrubbers are not necessary on

these systems, but bag filters are recommended.

D. IMPLEMENTATION

The purpose of this section is to provide information to applicants and licensees regarding

the NRC staff’s plans for using this draft regulatory guide. 

Except when an applicant or licensee proposes an acceptable alternative method for

complying with the specified portions of the NRC’s regulations, the methods in this guide

reflecting public comments, along with Regulatory Guide 3.5, “Standard Format and Content of

License Applications for Uranium Mills” (Ref. 8); Regulatory Guide 3.46, “Standard Format and

Content of License Applications, Including Environmental Reports, for In Situ Uranium Solution

Mining” (Ref. 9); Regulatory Guide 8.15, “Acceptable Programs for Respiratory Protection”

(Ref. 13); Regulatory Guide 8.22, “Bioassay at Uranium Mills” (Ref. 15); and Regulatory Guide

8.30, “Health Physics Surveys in Uranium Mills” (Ref. 12), will be used as the basis for evaluating

license applications and radiation safety and ALARA programs of NRC-licensed UR facilities.
1

 Requests for single copies of draft or active regulatory guides (which may be reproduced) or for placement on an automatic

distribution list for single copies of future draft guides in specific divisions should be made in writing to the U.S. Nuclear

Regulatory Commission, Washington, DC 20555, Attention: Reproduction and Distribution Services Section, or by fax to

(301)415-2289; email <DISTRIBUTION@NRC.GOV>. Copies are available for inspection or copying for a fee from the NRC

Public Document Room at 11555 Rockville Pike (first floor), Rockville, MD; the PDR’s mailing address is USNRC PDR,

Washington, DC 20555; telephone (301)415-4737 or 1-(800)397-4209; fax (301)415-3548; e-mail <PDR@NRC.GOV>.

2

 Copies are available at current rates from the U.S. Government Printing Office, P.O. Box 37082, Washington, DC 20402-9328

(telephone (202)512-1800); or from the National Technical Information Service by writing NTIS at 5285 Port Royal Road,

Springfield, VA 22161; (telephone (703)487-4650; <http://www.ntis.gov/ordernow>. Copies are available for inspection or

copying for a fee from the NRC Public Document Room at 11555 Rockville Pike, Rockville, MD; the PDR’s mailing address is

USNRC PDR, Washington, DC 20555; telephone (301)415-4737 or (800)397-4209; fax (301)415-3548; email is

PDR@NRC.GOV.

8.31-17

REFERENCES

1. USNRC, “Operating Philosophy for Maintaining Occupational Radiation Exposures As

Low As Is Reasonably Achievable,” Regulatory Guide 8.10, Revision 1 or 1R, May 1977.1

2. USNRC, "Final Generic Environmental Impact Statement on Uranium Milling Project

M-25," NUREG-0706, September 1980.2

3. USNRC, “Monitoring and Reporting Radioactivity in Releases of Radioactive Materials in

Liquid and Gaseous Effluents from Nuclear Fuel Processing and Fabrication Plants and

Uranium Hexafluoride Production Plants,” Regulatory Guide 4.14, Revision 1, December

1985.1

4. National Bureau of Standards, "Permissible Dose from External Sources of Ionizing

Radiation," Handbook 59 Recommendations of the National Council on Radiation

Protection, NCRP Report No. 17, Washington, DC, September 24, 1954.

5. National Council on Radiation Protection and Measurements, "Review of the Current State

of Radiation Protection Philosophy," Report No. 43, Washington, DC, January 15, 1975.

6. National Academy of Sciences - National Research Council, “The Effects on Populations

of Exposure to Low Levels of Ionizing Radiation,” Washington, DC, 1972.

7. Federal Radiation Council, “Background Material for the Development of Radiation

Protection Standards,” Report No.1, Washington, DC, 1960.

8. USNRC, “Standard Format and Content of License Applications for Uranium Mills,”

Regulatory Guide 3.5, Revision 1, November 1977.1

9. USNRC, “Standard Format and Content of License Applications, Including Environmental

Reports, for In Situ Uranium Solution Mining,” Regulatory Guide 3.46, June 1982.1

10. USNRC, “Instruction Concerning Prenatal Radiation Exposure,” Regulatory Guide 8.13,

Revision 3, June 1999.1
8.31-18

11. USNRC, “Instruction Concerning Risks from Occupational Radiation Exposure,”

Regulatory Guide 8.29, Revision 1, February 1996.1

12. USNRC, “Health Physics Surveys in Uranium Recovery Facilities,” Regulatory Guide

8.30, Revision 1, May 2002.1

13. USNRC, “Acceptable Programs for Respiratory Protection,” Regulatory Guide 8.15,

Revision 1, October 1999.1

14. USNRC, “Manual of Respiratory Protection Against Airborne Radioactive Materials,”

NUREG-0041, October 1976.2

15. USNRC, “Bioassay at Uranium Mills,” Regulatory Guide 8.22, Revision 1, August 1988.1
8.31-19

REGULATORY ANALYSIS

A separate regulatory analysis was not prepared for this Revision 1 to Regulatory Guide

8.31. A value/impact statement, which evaluated essentially the same subjects as are discussed in

a regulatory analysis, accompanied Regulatory Guide 8.31 when it was issued in May 1983.

A Revision 1 to Regulatory Guide 8.31 is needed to conform with the revised 10 CFR Part

20, “Standards for Protection Against Radiation,” as published May 21, 1991 (56 FR 23360). The

regulatory analysis prepared for 10 CFR Part 20 provides the regulatory basis for this Revision 1

of Regulatory Guide 8.31, and it examines the cost and benefits of the rule as implemented by the

guide. A copy of the “Regulatory Analysis for the Revision of 10 CFR Part 20" (PNL-6712,

November 1988), is available for inspection and copying for a fee in the NRC’s Public Document

Room at 11555 Rockville Pike, Rockville, MD; the PDR’s mailing address is USNRC PDR,

Washington, DC 20555; telephone (301)415-4737 or 1-(800)397-4209; fax (301)415-3548; e-mail

<PDR@NRC.GOV>.