ML12181A380

Draft Regulatory Guide Task OP 618-4, Information Relevant to Ensuring That Occupational Radiation Exposures at Nuclear Power Stations Will Be as Low as Is Reasonably Achievable (ALARA)

ML12181A380
Person / Time
Issue date:	05/31/1982
From:	Roecklein A Office of Nuclear Regulatory Research
To:
References
Task OP 618-4 RG-8.008, Rev. 4
Download: ML12181A380 (42)

Text

-U.S.

NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REGULATORY RESEARCH Division 8 DRAFT REGULATORY GUIDE AND VALUE/IMPACT STATEMENT Task OP 618-4

Contact:

A.

K.

Roecklein (301) 443-5970 SECOND PROPOSED REVISION 4* TO REGULATORY GUIDE 8.8 INFORMATION RELEVANT TO ENSURING THAT OCCUPATIONA'AL' RADIATION EXPOSURES AT NUCLEAR POWER STATIONS WILL BE AS LOW AS IS REASONABLY ACHIEVABLE (ALARA)---_

A.

INTRODUCTION Paragraph 20.1(c) of 10 CFR Part 20, "Stan-dardsifor' Protection Against Radiation," states that licensees should ma!e. evev'ry*reasonable effort to main-tain exposures to radiation as far below.the iimliits specified in Part 20 as is reasonably achievable.

This guide providd'_einormation relevant to attaining goals and objectives for planning,.' de'signinig, constructing, operating, and decommissioning -a light-water~reactor_(LWR) nuclear power plant to meet the criterion that exposures of('station personnel to radiation during routine operation of the station wii.'1be.,'as low as is reasonably achievable" (ALARA).

Additionally, this guide is responsive to the admonition of the Federal Radiation Council;';whose functions now reside in the Environmental Protection

• Since publlication in March 1979 of a proposed Revision 4 to this guide (Task6Hl*

50*7*4), several important new references have been developed.

Among thesehre'the Atomic Industrial Forum publication, "Compendium of Basic ALARA Design Features for Operating Nuclear Plants," and two regulatory guides concerning radiation protection training.

As a result of the incorporation of additional guidance into Regulatory Guide 8.8, this second proposed Revision 4 is being issued for public comment to obtain additional input.

Lines indicate substantive changes from the March 1979 proposed Revision 4.

1 The term "station personnel," as used in this guide, includes all persons employed by the licensee or by a contractor for the licensee who work at the station on a full-time or part-time basis.

This regulatory guide and the associated value/impact statement are being issued In draft form to involve the public in the early stages of the development of a regulatory position in this area.

They have not received complete staff review and do not. represent an official NRC staff position.

Public comments are being solicited on both drafts, the guide (including any implementation schedule) and the value/impact statement.

Comments on the value/Impact statement should he accompanied by supporting data.

Commnnts on both drafts should be sent to the Secretary of the Commission U. S.

laa RoquIatory Commission, Washington. D.C. 20555, Attention:

Docketing and Service Branch, byAUG 1,i' § Requests for single copies of draft guides (which may he reproduced) or for placement on an automatic distribution list for single copies of future draft guides in spPclfic divisions should be made in writing to the U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, Attention:

Director, Division of 1 echnical Information and Document. Countrol.

Agency (EPA),

that occupational radiation exposures be maintained ALARA.

Major accident situations and emergency procedures are not within the scope of this duide.

Much of the information presented in this guide is also applicable to nuclear power plants other than those cooled with light water.

The applicable goals and objectives should be used for all nuclear power stations until more specific goals and objectives are available for other types of power reactors (Ref.

1).

B.

DISCUSSION

1.

NEED FOR MAINTAINING DOSES ALARA IN A RADIATION PROTECTION PROGRAM The relationship between radiation dose and biological effects is reason-ably well known only for doses that are high compared with current annual dose 2

limits and only when such doses are delivered at a high dose rate.

An ad hoc committee of the National Council on Radiation Protection and Measurements (NCRP)

(Ref.

2) chose in 1959 to make the cautious assumptions that a proportional relationship exists between dose and biological effects and that the effect is not dependent on dose rate.

Essentially, this amounts to the assumption of a nonthreshold linear (straight line) dose-effect relationship.

The International Commission on Radiological Protection (ICRP),

the former Federal Radiation Council, whose functions are now within the Environmental Protection Agency (EPA),

and committees of the National Academy of Sciences/

National Research Council (NAS/NRC) have used this hypothesis to estimate conservatively the number of possible biological effects that statistically may be associated with exposures to radiation.

The NAS/EPA Biological Effects of Ionizing Radiation (BEIR)

Committee (Ref.

3) stated that the linear model probably leads to overestimates of the risk of most cancers, but can be used to define upper limits of risk.

The NRC position is that the assumption of a nonthreshold linear relationship between dose and biological effects independent of the dose rate should be applied for radiation protection purposes.

This linear model has been adopted 2Throughout this guide the word "dose" will allude to "dose equivalent," the term used for radiation protection purposes, with the unit expressed in rems.

2

by EPA (41 FR 28409) for the purpose of estimating the potential human health impact of low levels of ionizing radiation.

The primary objective of radiation protection is to reduce doses wherever and whenever reasonably achievable, thereby reducing the risk, which is assumed (for radiation protection purposes) to be proportional to the dose.

In 1973, the ICRP (Ref.

4) stated:

"Whilst the values proposed for maximum permissible doses are such as to involve a risk which is small compared to the other hazards of life, neverthe-less, in view of the incomplete evidence on which the values are based, coupled with the knowledge that certain radiation effects are irreversible and cumula-tive, it is strongly recommended that every effort be made to reduce exposure to all types of ionizing radiation to the lowest possible level."

Merely controlling the maximum dose to individuals, however, is not suffi-cient; the collective dose to the group, measured in man-rems, also must be kept as low as is reasonably achievable.

"Reasonably achievable" is judged by considering the state of technology and the economics of improvements in rela-tion to all the benefits from these improvements.

However, a comprehensive consideration of benefits and risks will include risks from nonradiological hazards.

An action taken to reduce radiation risks should not result in a significantly larger risk from other hazards.

Under the linear nonthreshold concept, restricting the doses to indivi-duals at a fraction of the applicable limit would be inappropriate if such action would result in the exposure of more persons to radiation and would increase the total man-rem dose because of nonproductive exposure.

The radia-tion protection3 community has recognized for many years that it is prudent to avoid unnecessary exposure to radiation and to maintain doses ALARA.

In addi-tion to reducing biological risks, ALARA practices may avoid costs for extra personnel to perform maintenance activities and nonproductive plant shutdown time caused by restrictions on station personnel working in radiation areas.

3 The term "radiation protection," as used in this guide, is considered to be synonymous with the term "applied health physics," i.e., the development and implementation of methods and procedures necessary to evaluate radiation hazards and to provide protection to man and his environment from unwarranted exposure.

3

Annual collective radiation dose equivalents received by personnel working at an LWR nuclear power plant have ranged from less than 100 man-rems to over 5000 man-rems (Refs.

5 and 6).

Typically, annual collective dose equivalents range from 400 to 1000 man-rems at LWR stations that have been in operation from 2 to 14 years and have generating capacities ranging from less than 100 MWe to 800 MWe.

In view of the anticipated growth of nuclear power stations over the next few decades and the radiation exposure experience to date, additional efforts to reduce radiation doses to nuclear power station personnel are warranted.

The wide range in collective radiation doses to station personnel among the various stations appears to be primarily a function of doses received in maintenance operations in radiation areas.

Some data are available to permit estimates of the distribution of doses among broad job categories and among the equipment systems or components that represent substantial sources of exposures.

Doses to station personnel are influenced by many variables, including (1) the ability of fuel elements to retain fission products, (2) the extent of deposition of activated corrosion products throughout the primary and auxiliary coolant systems, (3) the reliability of other specific equipment, (4) the station layout, and (5) the effectiveness of the radiation protection program.

If design reviews or inspections had revealed that radiation exposures at nuclear power stations were unavoidable or that the cost of reducing the exposures would be unreasonable, the exposures might be considered ALARA by definition.

However, this has not always been the case, and this guide is intended to assist in achieving a status wherein exposures are considered to be ALARA.

2.

PARAMETERS THAT AFFECT DOSE Specific design or operational objectives for maintaining radiation expo-sures ALARA are suggested by the parameters that determine the magnitude of doses to station personnel, both as individuals and as a group.

Doses to per-sonnel in nuclear power stations are predominantly from external exposure, i.e., from radiation sources external to the body.

However, there also exists a potential for doses from internal exposures, i.e., from radioactive materials taken into the body.

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Important parameters in determining doses from external exposures are (1) the length of time that the worker remains in the radiation field and (2) the intensity of the radiation field.

Some degree of exposure of station personnel cannot be avoided during the operation and maintenance of nuclear power stations.

However, there are many ways by which the exposures and resultant doses can be lowered by reducing these two parameters.

The intensity of the radiation field is determined by (1) the quantity of radioactive mate-rial, (2) the nature (i.e., characteristics) of the emitted radiation, (3) the nature of the shielding between the radiation source and the worker, and (4) the source geometry (e.g., distances and dimensions).

Parameters important in determining doses from internal exposures are (1) the quantity of radioactive material taken into the body, (2) the nature (isotopic and body deposition characteristics) of the material, and (3) the time interval over which the material is retained by the body.

The principal modes by which radioactive material can be taken into the body are (1) inhala-tion, (2) ingestion, (3) skin absorption, and (4) absorption through wounds.

At nuclear power stations, radioactive materials are generally confined, but

.some dispersion within the station is unavoidable and constitutes the source of (1) contaminated air and liquids that present the potential for intake by inhalation and absorption and (2) contaminated surfaces that present the potential for intake by ingestion and through cuts or abrasions in the skin.

Absorption generally is not an important intake mode at nuclear power stations except for tritium, which can be absorbed through the skin.

Consequently, the basic variables that can be controlled to limit doses from internal exposures are those that limit (1) the amount of contamination, (2) the dispersal of the contamination, and (3) the length of time that per-sonnel must spend in contaminated areas.

Protective equipment can keep the intake of the contaminant to a minimum.

Physical and chemical methods can be used to hasten the elimination of radioactive material taken into the body; however, because of the risks associated with the use of these methods, they are reserved for very serious cases in which the probability of experiencing biological effects is quite substantial, e.g., large intakes such as those that might occur in serious accident situations.

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3.

DOSE REDUCTION THROUGH EFFECTIVE DESIGN A major portion of the radiation exposure of station personnel is received during maintenance, radwaste handling, inservice inspection, refueling, and nonroutine operations (Ref.

7).

The decommissioning process also has a potential for substantial exposures to personnel.

Effective design of facilities and selection of equipment for systems that contain, collect, store, process, or transport radioactive material in any form will contribute to the effort to maintain radiation doses to station personnel ALARA.

Products of erosion or corrosion (i.e., "crud" 4 ) that become mobile and are activated constitute an important (perhaps principal) source of radiation with respect to the exposure of station personnel.

Crud is accumulated in and transported by the coolant.

Some componentý of the crud become radioactive when passing through the reactor core.

Migration of crud to other systems occurs with the movement of coolant or steam.

Specific radionuclides that have been identified in crud and that can contribute substantially to the radiation source are cobalt-58, cobalt-60, manganese-54, zirconium-65, and zirconium-95.

Exposures of station personnel who service equipment contaminated by crud can generally be reduced substantially by minimizing the formation of crud and by designing or modifying equipment to minimize locations where crud can deposit and accumulate.

Provisions for isolating components and flushing with crud-removing fluid such as demineralized water can often reduce accumulations prior to activities such as maintenance or equipment replacement.

Station and equipment layout also can affect the potential for radiation exposures.

Exposures at locations where multiple radiation sources exist sometimes can be reduced by additional separation of individual sources.

Adequate space for ease of maintenance and other operations can permit the tasks to be completed more quickly, thereby reducing the duration of exposure.

Shielding by structural materials and equipment and auxiliary or permanent shields can reduce exposures by isolating radiation sources.

Where equipment 4 "Crud" is a term used for corrosion and erosion products and other solids that are formed by chemical and physical reaction between the reactor coolant and structural materials.

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components constitute a substantial radiation source that cannot be effec-tively reduced in place, features that permit the removal of such components to remote locations for maintenance can effectively reduce exposures.

The use of remote-handling features also can reduce exposures of station personnel in certain instances.

4.

DOSE REDUCTION THROUGH ADMINISTRATIVE PROCEDURES Station technical and supervisory personnel, working closely with radia-tion protection personnel, can reduce exposures (1) by planning activities of personnel who must enter radiation areas, (2) by studying the actions and procedures of individuals working in such areas, and (3) by conducting post-operation debriefings on projects resulting in substantial exposures to identify how procedures might be modified to reduce exposures on subsequent similar tasks.

Training programs for all station personnel can establish and reinforce the principles of radiation protection as applied to specific job functions.

By making personnel aware of the methods and the special equipment and protective equipment available to them, potential radiation doses can be reduced.

5.

OBJECTIVES OF THE ALARA PROGRAM The concept of maintaining occupational radiation exposures ALARA does not embody a specific numerical guideline value at the present time.

Rather, it is a philosophy that reflects specific objectives for radiation dose management in:

1.

Developing a program to maintain occupational radiation exposures

ALARA,

2.

Designing facilities and selecting equipment,

3.

Implementing the radiation protection program with appropriate plans and procedures,

4.

Providing supporting equipment, instrumentation, and facilities.

When an adequate data base, including economic information, is available, the criteria for keeping annual collective doses to station personnel ALARA might be derived or selected in numerical terms.

However, a data base of operating experience and cost information to provide quantitative guidance for 7

establishing such criteria is not available at this time, and the criteria for meeting the provision of paragraph 20.1(c) of 10 CFR Part 20 must therefore take the form of qualitative guidance (e.g., objectives and statements of good practice).

The NRC staff has not performed a cost-benefit analysis for each of the considerations discussed or presented in Section C of this guide.

This guide presents goals and objectives that were selected to satisfy the principles, philosophy, and criteria for maintaining occupational radiation exposures ALARA.

Attaining these goals and objectives will require good engineering judgment on a case-by-case basis.

A cost-benefit analysis may be helpful in arriving at the judgment, but it should not be the decisive factor in all cases.

The nuclear steam supply system (NSSS) vendor, the designer, the architect-engineer (A/E),

the constructor, the worker, and the operator of the nuclear power facility each have responsibilities related to the effort of maintaining occupational radiation exposures ALARA.

Thus, coordination and cooperation are essential to achieving the objective of maintaining occupational radiation exposures ALARA.

This guide is written primarily for the applicant or licensee.

However, the designer, the A/E, and the constructor will find many of the guide's con-siderations helpful in the design and construction process to ensure that their efforts are consistent with the objective of the applicant or licensee to maintain radiation exposures ALARA.

Objectives stated in this guide for maintaining occupational radiation exposures ALARA are derived by considering the parameters that affect dose, the variables that exist in the station design features, and the variables that can be provided by station administrative actions.

Section C, Regulatory Position, states objectives in a manner that encourages innovation by permit-ting considerable flexibility on the part of the utility, the NSSS vendor, the designer, the constructor, and the A/E.

However the regulatory position also describes a large number of specific concerns that should be addressed in meeting these objectives.

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C.

REGULATORY POSITION Effort toward maintaining occupational radiation exposures as low as is reasonably achievable (ALARA) should be directed at both the annual dose to individual station personnel and the annual integrated, collective dose to station personnel (i.e., the sum of annual doses expressed in man-rems to all station personnel).

The NRC staff believes that the stated objectives are attainable by use of current technology and good operating practices.

The costs for attaining these objectives have not been established and are expected to vary widely depending on the features of the specific power reactor facility and the method selected to accomplish the objectives.

The favorable cost-benefit ratio for achieving some of these objectives may be obvious without a detailed study.

For other objectives, however, a cost-benefit study may be required to deter-mine whether the objectives are reasonably achievable.

Doses to station per-sonnel can affect station availability, and this factor should be considered in assessing the cost-benefit ratio.

Attaining the following objectives to the extent practicable throughout the planning, designing, constructing, operating, maintaining, and decommis-sioning of an LWR station will be considered to provide reasonable assurance that exposures of station personnel to radiation will be ALARA.

The methods are deliberately stated to allow flexibility in the manner by which the objec-tives can be achieved.

Differences among stations might require innovative methods to achieve the objectives.

1.

PROGRAM FOR MAINTAINING RADIATION DOSES TO STATION PERSONNEL ALARA To attain the integrated effort needed to keep exposures of station per-sonnel ALARA, each applicant and licensee should develop a radiation protection program with strong ALARA objectives that reflects the efforts to be taken by the utility, nuclear steam supply system vendor, and architect-engineer to reduce radiation exposure during all phases of a station's life.

This written program should contain sections that cover the generally applicable guidance presented in this guide, as a minimum, and more specific guidance as required to address the particular LWR that is the subject of the licensing action.

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This program should be combined with the station's radiation protection manual, safety analysis report, or other documents or submittals.

1.1 Establishing a Program To Maintain Occupational Radiation Doses ALARA A management policy for, and commitment to, ensuring that the exposure of station personnel to radiation will be ALARA should be established.

The policy and commitment should be reflected in written administrative procedures and instructions for operations involving potential exposures of personnel to radiation and should be reflected in station design features.

Instructions to designers, constructors, vendors, and station personnel speci-fying or reviewing station features, systems, or equipment should reflect the ALARA objectives.

(Few utilities design or build their nuclear power stations, but as customers of designers and builders, utilities should expect the designers and builders to be responsive to their needs and instructions.)

1.2 Organization, Personnel, and Responsibilities In view of the need for upper-level management support, responsibility and authority for implementing the program to maintain occupational radiation exposures ALARA should be assigned to a professional experienced in the field of radiation protection who has organizational freedom to ensure development and implementation of the program.

In addition, an ALARA committee should be established to review health physics programs and ALARA practices.

The ALARA committee should review in advance any task that is predicted to cause in excess of 10 man-rems.

The radiation protection manager (RPM)5 should, as a minimum, have the following responsibilities and authorities:

5 Professionals responsible for radiation safety are referred to by various titles such as "radiological safety officer," "radiation protection officer,"

"radiation safety officer," and "radiation protection manager."

This guide uses the title "radiation protection manager."

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1.

Ensuring that a corporate program that integrates management philosophy and regulatory requirements is established, including specific objectives for implementation; consideration should be given to establishing annual collective dose goals.

2.

Ensuring that an effective measurement system is established and used to determine the degree of success achieved by station operations with regard to the program goals and specific objectives.

3.

Ensuring that the measurement system results are reviewed on a periodic basis and that corrective actions are taken when attainment of the specific objectives appears to be jeopardized.

4.

Ensuring that the authority for implementing procedures and practices by which the specific goals and objectives will be achieved is delegated.

5.

Ensuring that the resources. needed to achieve goals and objectives to maintain occupational radiation exposures ALARA are made available.

In view of the responsibilities required to implement a program to main-tain occupational radiation exposures ALARA, the individual selected for this function might also be chosen to coordinate the effort among the several cor-porate functional groups such as the operations, maintenance, technical support, engineering, safety, and radiation protection groups and to represent the cor-porate interests in dealing with the NSSS designer, vendor, A/E, and builder during the design and construction phases.

If the corporation does not have the expertise for performing this function when the station is in the design stage, consultants who possess the required expertise should be used.

The utility should obtain assurance that available data and experience obtained from similar nuclear power stations are considered and reflected in the work of the NSSS designer, vendor, A/E, and builder so as to provide features in the new station that permit an effective ALARA program.

The plant manager (superintendent or equivalent) is responsible for all aspects of station operation, including the onsite radiation protection program.

Responsibilities of the Plant Manager with respect to a program to maintain occupational radiation exposures ALARA should include:

1.

Ensuring support from and direct involvement of all station personnel;

2.

Participating in the selection of specific goals and objectives for the station;

3.

Supporting the onsite radiation protection manager in formulating and implementing a station program in maintaining occupational radiation exposures ALARA; and

4.

Expediting the collection and dissemination of data and information concerning the program to the corporate management.

The onsite radiation protection manager has a safety function and respon-sibility to both employees and management that can best be fulfillec if the individual is independent of such station divisions as operations, maintenance, or technical support whose prime responsibility is continuity or improvement of station operability.

The RPM should have direct access to responsible management personnel in all matters related to the conduct of the radiation protection program.

The specific responsibilities given here for the RPM are illustrative and not intended to be all-inclusive with respect to the ALARA program or effort.

They do not include any of the responsibilities in areas other than ALARA efforts.

The responsibilities in the following listing marked with an asterisk are not solely those of the radiation protection manager.

Station supervisors and workers should also assume responsibility for these practices in their work areas.

The program should stress that all station employees should be actively involved in seeking new and better ways to perform work with less exposure.

Radiation protection in the nuclear plant is everyone's responsibility.

Responsibilities of the RPM and other supervisors (as indicated) with respect to a program to maintain occupational radiation exposures ALARA should include the following:

1.*

Participating in design reviews for facilities and equipment that can affect potential radiation exposures; 2.*

Identifying locations, operations, and conditions that have the poten-tial for causing significant exposures to radiation; 3.*

Initiating and implementing an exposure control program; this should include establishing annual collective dose goals for those activities that can reasonably be projected during the coming year.

4.*

Developing plans, procedures, and methods for keeping radiation exposures of station personnel ALARA; 5.*

Reviewing, commenting on, and recommending changes in job procedures Ito maintain exposures ALARA; a radiation work permit system should be initiated, 12

including a review by the radiation protection group (see Regulatory Position 3.1, Item 8);

6.*

Participating in the development and approval of training programs related to work in radiation areas or involving radioactive materials;

7.

Supervising the radiation surveillance program to maintain data on exposures of and doses to station personnel by specific job functions and type of work.

This could include establishing a monthly ALARA dose budget and job-specific dose goals;

8.

Supervising the collection, analysis, and evaluation of data and information obtained from radiological surveys and monitoring activities;6

9.

Supervising, training, and qualifying the radiation protection staff of the station; and

10.

Ensuring that adequate radiation protection coverage is provided for station personnel during all working hours.

Qualifications for the position of RPM, as well as for other positions in organizations operating nuclear power stations, are presented in Regulatory Guide 1.8, "Personnel Selection and Training" (RS 807-5, the second proposed Revision 2 to this guide was published for comment in September 1980).

1.3 Training and Instruction A training program in the fundamentals of radiation protection and in station exposure control procedures should be established.

It should include instructing all personnel whose duties require (1) working with radioactive materials, (2) entering radiation areas, or (3) directing the activities of others who work with radioactive materials or enter radiation areas.

The training program also should include sufficient instruction in the biological effects of exposures to radiation to permit the individuals receiving the instruction to understand and evaluate the significance of radiation doses in terms of the potential risks.

Assistance in setting up the training program may be found in Regulatory Guide 8.13, "Instruction Concerning Prenatal 6Data collected during outages can indicate trends of radiation buildup in equipment that can permit estimates of probable radiation levels to be encountered during subsequent outages.

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Radiation Exposure" (OP 031-4, a proposed Revision 2 to this guide was published for comment in August 1980); Regulatory Guide 8.27, "Radiation Protection Training for Personnel at Light-Water-Cooled Nuclear Power Plants"; and Regulatory Guide 8.29, "Instruction Concerning Risks from Occupational Radiation Exposure."

The training should be commensurate with the duties and responsibilities of those receiving the instructions, as well as with the magnitude of the potential doses and dose rates that can be anticipated.

Personnel (including contractor personnel) who direct the activities of others should be familiar with the licensee's radiation protection program and should have the authority to implement the licensee's commitment to ensure that the radiation exposures of station personnel will be ALARA.

The training program should include instruction on radiation protection rules for the station and the applicable Federal regulations.

Copies of these rules and regulations should be made available to those receiving the instruc-tion.

The training program should be approved by the RPM and presented by competent instructors.

The information presented in the training program should be reviewed periodically and modified as necessary to reflect contem-porary techniques and adjustments based on experience in station operations.

Instruction of station personnel should stress the importance of exposure-reduction efforts by every individual and should emphasize the need for feedback of information obtained when similar tasks were performed previously.

Station personnel should receive instruction at periodic intervals to reinforce their knowledge and keep it current.

Station personnel whose duties do not require entering radiation areas or working with radioactive materials should receive sufficient instruction in radiation protection and station rules and regulations to understand why they should not enter such areas.

Training programs that have as their goal an increase in craft skills provide a broader base of knowledgeable station personnel available to service equipment in radiation areas and permit the services to be performed more reliably and more efficiently.

This can promote lower individual and collec-tive dose levels.

I 1.4 Review of New or Modified Designs and Selection of Equipment Since several groups within a utility (e.g., maintenance, operations, radiation protection, technical support, engineering, and safety groups) are interested in station design and equipment selection, the utility should ensure that these groups are adequately represented in the reliability reviews of the design of the facility and the selection of equipment.

A coordinated effort by the several functional groups within the utility is required to ensure that station features will permit the objectives of the ALARA program to be achieved.

Although the A/E and designers greatly influence station design features, utilities should not delegate all responsibilities for station design review and equipment selection to the NSSS designer, vendor, or A/E.

Design concepts and station features should reflect consideration of the activities of station personnel (such as maintenance, refueling, inservice inspections, processing of radioactive wastes, decontamination, and decommis-sioning) that might be anticipated and that might lead to the exposure of personnel to substantial sources of radiation.

Radiation protection aspects of decommissioning should be factored into the planning, designing, construct-ing, and modifying activities.

Station design features should be provided to reduce the anticipated exposures of station personnel to these sources of radiation to the extent practicable.

Specifications for equipment should reflect the objectives of the ALARA program, including considerations of reliability, serviceability, limitations of internal accumulations of radioactive material, and other features addressed in this guide.

Specifications for replacement equipment also should reflect modifications based on experience gained from using the original equipment.

2.

CONSIDERATIONS ON DESIGN OR MODIFICATION OF FACILITIES AND EQUIPMENT Radiation sources within a nuclear power station differ appreciably with respect to location, intensity, and characteristics.

The magnitude of the dose rates that result from these sources is dependent on many factors, including the facility and equipment design and layout, the mode and length of operation, and the radiation source strength and characteristics.

Two publications by the Atomic Industrial Forum entitled "Compendium of Basic ALARA Design Features for Operating Nuclear Plants" and "An Assessment of Engineering Techniques for 15

Reducing Occupational Radiation Exposure at Operating Nuclear Power Plants" have been evaluated by the NRC staff and are considered to provide useful guidance for achieving ALARA design objectives. 7 To provide a basis for design or modification, the quantity and isotopic composition of the radioactive material that can be anticipated to be contained, deposited, or accumulated in the station equipment should be estimated.

Fission product source terms should be estimated using these bases:

(1) an offgas rate lof 100,000 pCi/sec after a 30-minute delay for boiling water reactors and (2) 0.25 percent fuel cladding defects for pressurized water reactors.

Activation source terms, including activated corrosion products, should be based on measurements and experience gained from operating stations of similar design.

ANSI N237-1976/ANS 18.1-1976, "Source Term Specification,'8 is based on such experience and provides information that can be used as a basis for estimating activation source terms.

When operating measurements are used, extrapolation of data to equilibrium conditions may be needed to estimate ultimate activation source terms.

Neutron and prompt gamma source terms should be based on applicable operating experience and reactor core physics calculations.

ALARA program objectives are presented below for each of several station features or functions.

Each objective is followed by a number of specific concerns or suggestions that should be addressed.

2.1 Access Control of Radiation Areas To avoid unnecessary and inadvertent exposures of personnel to radiation, the magnitude of the potential dose rates at all locations within the station Ishould be estimated during station design and modification.

Actual dose rates should be measured periodically during operation to determine current exposure potentials.

Zones associated with the higher dose rates should be kept as small as reasonably achievable consistent with accessibility for accomplishing the 7 Copies may be obtained from the Atomic Industrial Forum, 7101 Wisconsin Avenue, Bethesda, Maryland 20014.

8 Copies may be obtained from the American Nuclear Society, 555 North Kensington

Avenue, La Grange Park, Illinois 60525.

16

services that must be performed in those zones, including equipment laydown requirements.

Radiation zones where station personnel spend substantial time should be designed to the lowest practical dose rates.

It is common practice to identify radiation zones within a nuclear power station.

The zone designations are established to reflect the design maximum dose rates that may exist in areas within the station where station personnel must have access to perform required services.

Several systems for designating "radiation zones" currently exist among the utilities, and Working Group ANS-6.7 of the American Nuclear Society has developed a draft standard dated April 1981, ANSI/ANS-6.7.1, "Radiation Zoning for Design of Nuclear Power Plants, "9 that should prove useful in attaining common designations and termi-nology in this matter.

To avoid ambiguity, no reference to radiation zone numbers is made in this guide at this time.

A system should be established to permit effective control over personnel access to the radiation areas and control over the movement of sources of radiation within the station.

Where high radiation areas (>100 mrem/h) exist,

§ 20.203 of 10 CFR Part 20 requires that station design features and administra-tive controls provide positive access control, ease of egress, and appropriate warning devices and notices.

Access control of. radiation areas also should reflect the following considerations:

1.

Extraordinary design features are warranted to avoid any potential dose to personnel that is large enough to cause acute biological effects or that could be received in a short period of time.

Positive control of ingress to such areas, permanent shielding, source removal, or combinations of these alternatives can reduce the dose potential.

2.

Administrative controls such as standard operating procedures can be effective in preventing inadvertent exposures of personnel and the spread of contamination when radioactive material or contaminated equipment must be transported from one location to another and when the route of transport through lower radiation zones or "clean" areas cannot be avoided.

3.

Station features such as platforms or walkways, stairs, or ladders that permit prompt accessibility for servicing or inspection of components 9See footnote 8 on page 16.

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located in higher radiation zones can reduce exposure of personnel who must perform these services.

2.2 Radiation Shields and Geometry Radiation shields should be designed using the design basis assumptions explained in Regulatory Position 2 and conservative assumptions for geometries.

Calculational methods known to provide reliable and accurate results (i.e.,

methods and modeling techniques that have been demonstrated to give acceptable accuracy in analyses similar to the problem of concern) should be used to deter-mine appropriate shield thicknesses.

Shield design features should reflect the following considerations to maintain occupational radiation exposures ALARA:

1.

Exposure of personnel servicing a specific component (such as a pump, filter, or valve) to radiation from other components containing radioactive material can be reduced by providing shielding between the individual components that constitute substantial radiation sources and the worker.

2.

Where it is impractical to provide permanent shielding for individual components that constitute substantial radiation sources, the exposure of per-sonnel maintaining such components can be reduced (a) by providing as much distance as practicable between the components that must be serviced and the substantial radiation sources in the area and (b) by providing temporary shields around components that contribute substantially to the dose rate.

3.

Potential exposure of station personnel to radiation from certain systems containing radiation sources can be reduced by a station layout that permits the use of distance and shielding between the sources and work locations.

These systems include, but are not limited to, the NSSS and the reactor water cleanup, offgas treatment, solid waste treatment, and storage systems, as well as systems infrequently containing radiation sources such as the standby gas treatment and residual heat removal systems.

Radiation from an operating BWR turbine can constitute a substantial source of exposure for construction personnel or others who have access to the site for extended periods of time if insufficient shielding is provided.

4.

Streaming or scattering of radiation from components with local shielding (such as cubicles) can be reduced by providing labyrinths for access.

However, such labyrinths or other design features of the cubicle should permit the components to be removed readily from the cubicle for repair or replacement 18

if such work is expected or anticipated.

Single-scatter labyrinths may be inadequate if the cubicle contains a substantial radiation source.

5.

Streaming of radiation into accessible areas through penetrations for pipes, ducts, and other shield discontinuities can be reduced (a) by layouts that prevent substantial radiation sources within the shield from being aligned with the penetrations or (b) by using "shadow" shields, i.e., shields of limited size that attenuate the direct radiation component.

Streaming also can occur through roofs or floors unless adequate shielding encloses the source from all directions.

6.

The exposure of station personnel to radiation from pipes carrying radioactive material can be reduced by shielded chases.

7.

Design features that permit the rapid removal and reassembly of shielding, insulation, and other material from equipment that must be inspected or serviced periodically can reduce the exposure of station personnel perform-ing these activities.

8.

Space within cubicles and other shielding to provide laydown space for special tools and ease of servicing activities can reduce potential doses

.by permitting the services to be accomplished expeditiously, thus reducing exposure time.

9.

The exposure of personnel who service components that constitute substantial radiation sources or are located in high radiation fields can be minimized by removing the components and transporting them to low radiation zones where shielding and special tools are available.

Design features that permit the prompt removal and installation of these components can reduce the exposure time.

10.

The spent fuel transfer system involves extremely high radiation levels during fuel transfer; thus, the design of shielding for this system requires special attention.

Special attention is also required in the design of the necessary positive access control and the procedures for administering it.

11.

Floor and equipment drains, piping, and sumps that are provided to collect and route any contaminated liquids that might leak or be spilled from process equipment or sampling stations can become substantial radiation sources.

The drain lines can be located in concrete floors, concrete ducts, columns, or radwaste pipe chases to provide shielding.

These systems can also become a source of airborne contamination because of the potential for gases to form in and be released by such systems (see Regulatory Position 2.4).

19

2.3 Process Instrumentation and Controls Appropriate station layout and design features should be provided to reduce the potential doses to personnel who must operate, service, or inspect station instrumentation and controls.

The following considerations should be reflected in selecting the station features:

1.

The exposure of personnel who must manually operate valves or controls can be reduced through the use of "reach rods" or remotely operated valves or controls.

However, these devices can require lubrication and maintenance that can be the source of additional exposures, and these factors should be taken into consideration.

2.

The exposure of personnel who must view or operate instrumentation, monitors, and controls can be reduced by locating the readouts or control points in low radiation zones.

As radiation levels build up, consideration should be given to relocation of readouts or control points.

3.

Instrumentation must satisfy functional requirements, but the exposure of personnel can be reduced if the instruments are designed, selected, specified, and located with consideration for long service life, ease and low frequency of maintenance and calibration, and low crud accumulation.

Operating experience should be recorded, evaluated, and reflected in the selection of replacement instrumentation.

4.

The use of instrumentation that contains minimal quantities of con-taminated working fluid (e.g., pressure transducers rather than bellows-type pressure gauges) can reduce the potential for exposure at the readout locations.

2.4 Control of Airborne Contaminants and Gaseous Radiation Sources Station design features should be provided in all station work areas to limit the average concentrations of radioactive material in air to levels well below the values listed in 10 CFR Part 20, Appendix B, Table I, Column 1.

Effective design features can minimize the occurrence of occasional increases in air contamination and the concentrations and amounts of contaminants asso-ciated with any such occasional increases.

Designs that permit'repeated -'!,

identified releases of large amounts of radioactive materials into the air spaces occupied by personnel are contrary to a program to maintain occupational radiation exposures ALARA.

20

Station design features should provide for protection against air-borne radioactive material by means of engineering controls such as process, containment, and ventilation equipment.

The routine provision of respiratory protection by the use of individually worn respirators rather than by engineered design features is generally unacceptable.

The use of respirators, however, may be appropriate in certain nonroutine or emergency operations when the application of engineering controls is not feasible or while such controls are being installed.

The approved use of respirators is subject to the requirements of § 20.103, "Exposure of Individuals to Concentrations of Radioactive Materials in Air in Restricted Areas," of 10 CFR Part 20 and to regulatory guidance on acceptable use.

(See Regulatory Guide 8.15, "Acceptable Programs for Respiratory Protec-tion," and NUREG-0041, "Manual of Respiratory Protection Against Airborne Radioactive Materials." 1 0 )

Design features of the station ventilation system and gaseous radwaste processing systems should reflect the following considerations:

1.

The spread of airborne contamination within the station can be limited by maintaining air pressure gradients and airflows from areas of low potential airborne contamination to areas of higher potential contamination.

Periodic checks would ensure that the design pressure differentials are being maintained.

2.

Effectively designed ventilation systems and gaseous radwaste treatment systems will contain radioactive material that has been deposited, collected, stored, or transported within or by the systems.

Exposures of station personnel to radiation and to contamination from ventilation or gaseous radwaste treatment components occur as a result of the need to service, test, inspect, decontaminate, and replace components of the systems or perform other duties near these systems.

Potential doses from these systems can be minimized by providing ready access to the systems, by providing space to permit the activ-ities to be accomplished expeditiously, by separating filter banks and com-ponents to reduce exposures to radiation from adjacent banks and components, and by providing sufficient space to accommodate auxiliary ventilation or shielding of-:components.

10Copies of NUREG-0041 may be obtained from the U.S. Nuclear Regulatory Com-mission, ATTN:

Sales Manager, Washington, D.C.

20555, or the National Technical Information Service, Springfield, Virginia 22161.

21

3.

Auxiliary ventilation systems that augment the permanent system can provide local control of airborne contaminants when equipment containing potential airborne sources is opened to the atmosphere.

Two types of auxiliary ventilation systems have proved to be effective.

In areas where contaminated equipment must be opened frequently, dampers and fittings can be provided in ventilation ducts to permit the attachment of flexible tubing or "elephant trunks" without causing an imbalance in the ventilation system.

In areas where contaminated equipment must be opened infrequently, portable auxiliary ventila-tion systems featuring blowers, high-efficiency particulate air (HEPA)

filters, and activated charcoal filters (where radioiodine might be anticipated) on carts can be used effectively.

Portable auxiliary ventilation systems should be tested frequently to verify the efficiency of the filter elements in their mountings.

When the efficiency has been verified, the system may be exhausted to the room or the ventilation exhaust duct without further treatment and thus an imbalance in the permanent ventilation system can be avoided.

4.

Machining of contaminated surfaces (e.g., welding, grinding, sanding, or scaling) or "plugging" of leaking steam generator or condenser tubes can be substantial sources of airborne contamination.

These sources can be controlled by using auxiliary ventilation systems.

5.

Sampling stations for primary coolant or other fluids containing high levels of radioactive material can constitute substantial sources of airborne contamination.

Such sources can be controlled by using auxiliary ventilation systems.

6.

Wet transfer or storage of potentially contaminated components will minimize air contamination.

This can be accomplished by keeping contaminated surfaces wet by spraying or, preferably, by keeping such surfaces under water.

2.5 Crud Control Design features of the primary coolant system, the selection of construc-tion materials that will be in contact with the primary coolant, and features of equipment that treat primary coolant should reflect considerations that will reduce the production and accumulation of crud in stations where it can cause high exposure levels.

The following items should be considered in the crud control effort:

22

1.

Production of cobalt-58 and cobalt-60, which constitute substantial radiation sources in crud, can be reduced by specifying, to the extent practi-cable, materials with low nickel and low cobalt contents for primary coolant pipe, tubing, internal vessel surfaces, heat exchangers, wear materials, and other components that are in contact with primary coolant.

Alternative materials for hard facings of wear materials of high cobalt content should be considered if these high-cobalt materials contribute to the overall exposure levels.

Such consideration should also take into account potential increased service/repair requirements and the overall reliability of the old and new materials.

Alternatives for high-nickel alloy materials (e.g.,

Inconel 600) should be considered if it is shown that these materials contribute to overall exposure levels.

Such consideration should also take into account potential increased service/repair requirements and overall reliability of the old and new materials.

2.

Loss of material by erosion of load-bearing hard facings can be reduced by using favorable geometries and lubricants, where practicable, and by using controlled leakage purge across journal sleeves to avoid entry of particles into the primary coolant.

3.

Loss of material by corrosion can be reduced by continuously monitoring and adjusting oxygen concentration and pH in primary coolant above 250'F and by using bright hydrogen-annealed tubing and piping in the primary coolant and feedwater systems.

4.

Consideration should be given to cleanup systems (e.g.,

using graphite or magnetic filters) for removal of crud from the primary coolant during operation.

5.

Deposition of crud within the primary coolant system can be reduced by providing laminar flow and smooth surfaces for the coolant and by minimizing crud traps in the system.

2.6 Isolation and Decontamination Potential doses to station personnel who must service equipment containing radioactive sources can be reduced by removing such sources from the equipment (decontamination) prior to servicing.

Systems and components that must be serviced and that constitute a substantial radiation source should be designed, 23

to the extent practicable, with features that permit isolation and decontami-nation.

Station design features should consider the ultimate decommissioning of the facility and the following concerns:

1.

The necessity for decontamination can be reduced by limiting the deposition of radioactive material within the processing equipment--particularly in the "dead spaces" or "traps" in components where substantial accumulations can occur.

The deposition of radioactive material in piping can be reduced and decontamination efforts enhanced by avoiding stagnant legs, by locating connections above the pipe centerline, by using sloping rather than horizontal runs, and by providing drains at low points in the system.

2.

The need to decontaminate equipment and station areas can be reduced by taking measures that will reduce the probability of release, reduce the amount released, and reduce the spread of the contaminant from the source (e.g.,

from systems or components that must be opened for service or replacement).

Such measures can include auxiliary ventilation systems (see Regulatory Position 4.2), treatment of the exhaust from vents and overflows (see Regula-tory Position 2.8), drainage control such as curbing and floors sloping to local drains, or sumps to limit the spread of contamination from leakage of liquid systems.

3.

Accumulations of crud or other radioactive material that cannot be avoided within components or systems can be reduced by providing features that will permit the recirculation or flushing of fluids with the capacity to remove the radioactive material through chemical or physical action.

The fluids con-taining the contaminants will require treatment, and this source should be considered in sizing station radwaste treatment systems.

4.

Continuity in the functioning of processing or ventilation systems that are important for controlling potential doses to station personnel can be provided during servicing of the systems if redundant components or systems are available so that the component (with associated piping) being serviced can be isolated.

5.

The potential for contamination of "clean services" (such as station service air, nitrogen, or water supply) from leakage from adjacent systems con-taining contaminants can be reduced by separating piping for these services from piping that contains radioactive sources.

Piping that carries radioactive sources can be designed for the lifetime of the station, thus avoiding the 24

necessity for replacement (and attendant exposures) and lessening the poten-tial for contamination of clean services if it is impracticable to provide isolation through separate chases.

6.

Surfaces can be decontaminated more expeditiously if they are smooth, nonporous, and free of cracks, crevices, and sharp corners.

These desirable features can be realized by specifying appropriate design instructions, by giving attention to finishing work during construction or manufacture, and by using sealers such as special paints on surfaces where contamination can be anticipated.

(ANSI N101.2-1972, "Protective Coatings (Paints) for Light Water Nuclear Reactor Containment Facilities," 1 1 provides helpful guidance on this matter.)

7.

If successful decontamination of important systems could be prevented by an anticipated failure of a critical component or feature, additional features that permit alternative decontamination actions can be provided.

8.

Contaminated water and deposited residues in spent fuel storage pools contribute to the exposure at accessible locations in the area.

Treatment systems that remove contaminants from the water can perform more efficiently (a) if intake and discharge points for the treatment systems are located to provide enhanced mixing and to avoid stagnation areas in the pool and (b) if pool water overflows and skimmer tanks are provided.

Fluid jet or vacuum-cleaner-type agitators can help reduce the settling of crud on surfaces of the pool system.

2.7 Radiation Monitoring Systems Central or "built-in" monitoring systems that give information on the dose rate and concentration of airborne radioactive material in selected station areas can reduce the exposure of station personnel who would be required to enter the areas to obtain the data if such systems were not provided.

(Guidance on these systems is being developed in ANS/HPS-6.8.1-1981, "Location and Design Criteria for Area Radiation Monitoring Systems for Light Water Reactors.") 12 These systems also can provide timely information regarding 11Copies may be obtained from the American National Standards Institute, 1430 IBroadway, New York, New York 10018.

12 See footnote 8 on page 16.

25

changes in the dose rate or concentrations of airborne radioactive material in the areas.

The installation of a central monitoring system is easier and less expensive if it is a part of the original station design.

The selection or design and installation of a central monitoring system should include consid-eration of the following desirable features:

1. Readout capability at the main radiation protection access control point;

2.

Placement of detectors for optimum coverage of areas (Ref.

7);

3.

Circuitry that indicates component failure;

4.

Local alarm and readout;

5.

Clear and unambiguous readout;

6.

Ranges adequate to ensure readout of the highest anticipated radiation levels and to ensure positive readout at the lowest anticipated levels; and

7.

Capability to record the readout of all systems.

8.

Airborne radioactivity monitors should be upstream of filters for occupational radiation monitoring purposes.

2.8 Resin and Sludge Treatment Systems Systems used to transport, store, or process resins or slurries of filter sludge present a special hazard because of the concentrated nature of the radio-active material.

Design features for resin-and sludge-handling systems should reflect this concern and the following specific considerations:

1.

The accumulation of radioactive material in components of systems used to process resin and sludges can be reduced by (a) reducing the length of piping runs, (b) using larger diameter piping to minimize plugging without reducing velocity, (c) reducing the number of pipe fittings, (d) avoiding low points and dead legs in piping, (e) using gravitational flow to the extent practicable, and (f) minimizing flow restrictions of processed material.

2.

The need for maintenance in the presence of intense local radiation sources can be reduced by using full-ported valves constructed so that the slurry will not interfere with the opening or closing of the valve and avoid-ing cavities in valves.

3.

The deposition of resin and sludge that would occur if elbow fittings were used can be reduced by using pipe bends at least five pipe diameters in radius.

Where pipe bends cannot be used, long-radius elbows are preferred.

0 26

4.

Smoother interior pipe surfaces at connections (with attendant reduc-tions in friction losses, deposition of material, and tendencies to "plug")

can be achieved by using butt welds rather than socket welds and by using con-sumable inserts rather than backing rings.

5.

Where the use of tees cannot be avoided, line losses can be reduced if the flow is through the run (straight section) of the tee, and accumulations of material in the branch of the tee can be reduced by orienting the branch horizontally or (preferably) above the run.

6.

Slurry piping is subject to plugging that may require backflushing from the tank and equipment isolation valves and pressurizing with water, nitrogen, or air to "blow out" plugged lines.

Using pressurized gas for blow-ing out lines should be done cautiously since this can present a potential contamination source.

7.

Water, air, or nitrogen for sparging can be used to fluidize resins or sludges in storage tanks.

The use of gases, however, presents a potential source of airborne contamination and tank rupture from overpressures.

8.

The spread of contamination by the loss of resin or sludge through overflows and vents can be reduced by using screens, filters, or other features thatwill collect and retain solids.

However, such features generally require cleaning by remote flushing, by rapid replacement, or by other means to reduce exposures during servicing.

Consideration should be given to ANSI/ANS 55.6-1979, "Liquid Radioactive

,13 Waste Processing Systems for Light Water Reactor Plants,"

and ANSI/ANS 55.1-1979, "Solid Radioactive Waste Processing System for Light Water Cooled Reactor Plants."' 1 3 These standards cover some aspects of slurry systems.

2.9 Other Features Station layout and station tasks should be reviewed to identify and provide special features that complement the ALARA program.

Station design should reflect consideration of the following concerns:

1.

The selection of radiation-damage-resistant materials for use in high radiation areas can reduce the need for frequent replacement and can reduce the probability of contamination from leakage.

1 3 See footnote 8 on page 16.

27

2.

The use of stainless steel for constructing or lining components, where it is compatible with the process, can reduce corrosion and can provide options for decontamination methods.

The relatively high activation potential for such components of stainless steel as nickel and cobalt needs also to be considered.

3.

Field-run piping that carries radioactive material can cause unnecessary exposures unless due consideration is given to the routing.

Such unnecessary exposures can be avoided if the routing is accomplished under the cognizance of an individual familiar with the principles of radiation protection or if a detailed piping layout is provided, i.e., if the piping is not field run.

4.

If filters or other components that may need servicing can constitute substantial radiation sources, exposures can be reduced by providing features that permit operators to avoid the direct radiation beam and that provide remote removal, installation, or servicing.

Standardization of filters should be considered.

5.

The servicing of valves can be a substantial source of doses to station personnel.

These doses can be reduced by providing adequate working space for easy accessibility and by locating the valves in areas that are not in high radiation fields.

6.

Leakage of contaminated coolant from the primary system can be reduced by using live-loaded valve packings and bellows seals.

7.

Potential doses from servicing valves and from leakage can be reduced by specifying and installing reliable valves for the required service, by using radiation-damage-resistant seals and gaskets, and by using valve back seats.

The use of straight-through valve configurations can avoid the buildup of accumulations in internal crevices and the discontinuities that exist in valves of other configurations.

In most cases, valves can be installed in the "stem-up" orientation to facilitate maintenance and to minimize crud traps.

The desired features are reliability, good performance, and the ability to be maintained infrequently and rapidly.

8.

Leaks from pumps can be reduced by using canned pumps if they are compatible with the service needs and lower personnel exposures can be achieved thereby.

If mechanical seals are used on a pump in a slurry service, features that permit the use of flush water to clean pump seals can reduce the accumu-lation of radioactive material in the seals.

Drains on pump housings can reduce the radiation field from this source during servicing.

Provision for the collection of such leakage or disposal to a drain sump is appropriate.

28

9.

The sources of radiation from sedimentation that occurs in tanks used to process liquids containing radioactive material and residual liquids can be reduced when servicing by draining the tanks.

The design can include sloping the tank bottoms toward outlets leading to other reprocessing equip-ment and, where practicable, providing built-in spray or surge features.

10.

Spare connections on tanks or other components located in higher radiation zones may be desirable to provide flexibility in operations.

Exposures of personnel can be avoided if these connections are provided as a part of the original equipment rather than by subsequent modification of the equipment in the presence of radiation.

11.

Inspections to satisfy Section XI of the ASME Boiler and Pressure Vessel Code 1 4 and regulatory requirements can result in exposures of station personnel to radiation.

Many of the objectives presented above will aid in reducing potential exposures to personnel who perform the required inspec-tions.

Station features and design should, to the extent practicable, permit inspections to be accomplished expeditiously and with minimal exposure of personnel.

The effort to maintain occupational radiation exposures ALARA can also be aided by prompt accessibility, shielding and insulation that can be quickly removed and reinstalled, and special tools and instruments that reduce exposure time or permit remote inspection of components or equipment contain-ing potential radiation sources.

12.

Components can be removed from processing systems more expeditiously if adequate space is provided in the layout of the system and if the intercon-nections permit prompt disconnects.

13.

Station features that provide a favorable working environment such as adequate lighting, ventilation, working space, and accessibility (e.g.,

via working platforms, cat walks, and fixed ladders) can promote work efficiency.

14.

The exposure of station personnel who must replace lamps in high radiation areas can be reduced by using extended service lamps and by providing design features that permit the servicing of the lamps from lower radiation areas.

14 Copies may be obtained from the American Society of Mechanical Engineers, United Engineering Center, 345 East 47th Street, New York, New York 10017 29

15.

An adequate emergency lighting system can reduce potential exposures of station personnel by permitting prompt egress from high radiation areas if the station lighting system fails.

3.

IMPLEMENTING THE RADIATION PROTECTION PROGRAM A substantial portion of the radiation dose to station personnel is received while they are performing services such as maintenance, refueling, and inspection in high radiation areas.

The objectives that were presented in Regulatory Posi-tion 2 can provide station design features conducive to an effective program to maintain occupational radiation exposures ALARA.

However, an effective pro-gram also requires station operational considerations in terms of procedures, job planning, recordkeeping, special equipment, operating philosophy, and other support.

This section deals with the manner in which the station administrative efforts can influence (1) the number of persons who must enter high radiation areas or contaminated areas, (2) the period of time the persons must remain in these areas, and (3) the magnitude of the potential dose.

3.1 Preparation and Planning Before entering radiation areas where significant doses could be received, station personnel should have the benefit of preparations and plans that can ensure that the exposures are ALARA while the personnel are performing the services.

Preparations and plans should reflect the following considerations:

1.

A staff member who is a specialist in radiation protection can be assigned the responsibility for contributing to and coordinating ALARA efforts in support of operations that could result in substantial individual and collec-tive dose levels.

2.

To provide the bases for planning the activity, surveys can be performed to ascertain information with respect to radiation, contamination, airborne radioactive material, and mechanical difficulties that might be encountered while performing services.

3.

Radiation surveys provided in conjunction with inspections or other activities can define the nature of the radiation fields and identify favor-able locations where personnel may take advantage of available shielding, distance, geometry, and other factors that affect the magnitude of the dose 30

rate or the portions of the body exposed to the radiation.

Computerized sur-vey graphic mapping systems are available and useful.

4.

Photographs of "as-installed" equipment or components can be valuable for planning purposes and can be augmented by additional photos taken during the surveys.

The use of portable TV cameras with taping features has consider-able merit as both an operational aid and a teaching aid.

5.

The existing radiation levels frequently can be reduced by draining, flushing, or other decontamination methods or by removing and transporting the component to a lower radiation zone.

An estimate of the potential doses to station personnel expected to result from these procedures is germane in select-ing among alternative actions.

6.

A preoperational briefing for personnel who will perform services in a high radiation area can ensure that service personnel understand the tasks about to be performed, the information to be disseminated, and the special instructions to be presented.

7.

A program can be implemented to provide access control and to limit exposures to those persons needed to perform the required services in the radiation areas.

Such a program would address conditions that require a special work permit or other special procedures.

8.

A work permit form with an appropriate format can be useful for recording pertinent information concerning tasks to be performed in high radiation areas so that the information is amenable to cross-referencing and statistical analysis.

Information of interest would include the following items:

a.

Designation of services to be performed on specific components, equipment, or systems;

b.

Number and identification of personnel working on the tasks;

c.

Anticipated radiation, airborne radioactive material, and con-tamination levels based on current surveys of the work areas and date of survey;

d.

Monitoring requirements such as continuous air monitoring or sampling equipment;

e.

Estimated exposure time required to complete the tasks and the estimated doses anticipated from the exposure; 31

f.

Special instructions and equipment to minimize the exposures of personnel to radiation and contamination;

g.

Protective clothing and equipment requirements;

h.

Personnel dosimetry requirements;

i.

Authorization to perform the tasks; and J.

Actual exposure time, doses, and other information obtained during the operation.

9.

Consideration of the potential for accident situations or unusual occurrences (such as gross leakage of contamination, pressure surges, fires, cuts, punctures, or wounds) and contingency planning can reduce the potential for such occurrences and enhance the capability for coping with the situations expeditiously if they occur.

10.

Portable or temporary shielding can reduce dose rate levels near hot spots and in the general area where the work is to be performed.

11.

Portable or temporary ventilation systems or contamination enclosures and expendable floor coverings can control the spread of contamination and limit the intake by workers through inhalation.

12.

Dry runs on mockup equipment can be useful for training personnel, identifying problems that can be encountered in the actual task situation, and selecting and qualifying special tools and procedures to reduce potential exposures of station personnel.

13.

Adequate auxiliary lighting and a comfortable environment (e.g.,

vortex tube coolers for supplied-air suits) can increase a worker's efficiency and thus reduce the time spent in the higher radiation zones.

14.

Radiation monitoring instruments selected and made available in adequate quantities can permit accurate measurements and rapid evaluations of the radiation and contamination levels and changes in levels when they occur.

Routine calibration of instruments with appropriate sources and testing can ensure operability and accuracy of measurements.

15.

Performing work on some components inside disposable tents or, for less complicated jobs, inside commercially available disposable clear plastic glove bags can limit the spread of contamination.

Such measures can also avoid unnecessary doses resulting from the need to decontaminate areas to permit personnel access or to allow for entry with less restrictive protective clothing and equipment requirements.

32

16.

Performing work on some components under water using diving techniques for underwater maintenance, repair, or retrieval of lost parts can result in lower cumulative radiation exposure as well as saving time.

17.

Careful scheduling of inspections and other tasks in high radiation areas can reduce exposures by permitting decay of radiation sources during the reactor shutdown period and by eliminating some repetitive surveys.

Data from surveys and experience obtained in previous operations and current survey data can be factored into the scheduling of specific tasks.

3.2 Operations During operations in radiation areas, adequate supervision and radiation protection surveillance should be provided to ensure that the appropriate procedures are followed, that planned precautions are observed, and that all potential radiation hazards that may develop or that may be recognized during the operation are addressed in a timely and appropriate manner.

Assigning a health physics (i.e., radiation safety or radiation protec-tion) technician the responsibility for providing radiation protection surveillance for each shift operating crew can help ensure adequate radiation protection surveillance.

Personnel monitoring equipment such as direct-reading dosimeters, audible-alarm dosimeters, and personal dose rate meters can be used to provide early evaluation of doses to individuals and the assignment of those doses to specific operations (see Regulatory Guides 1.16, "Reporting of Operating Information--

Appendix A Technical Specifications," 8.4, "Direct-Reading and Indirect-Reading Pocket Dosimeters," and 8.28, "Audible-Alarm Dosimeters").

Communication systems between personnel in high radiation zones and personnel who are monitoring the operation in other locations can permit timely exchanges of information and avoid unnecessary exposures to monitoring personnel.

3.3 Postoperations Observations, experience, and data obtained during nonroutine operations in high radiation zones should be ascertained, recorded, and analyzed to identify deficiencies in the program and to provide the bases for revising 33

procedures, modifying features, or making other adjustments that may reduce exposures during subsequent similar operations.

Formal or informal postoperation debriefings of station personnel perform-ing the services can provide valuable information concerning shortcomings in preoperational briefings, planning, procedures, special tools, and other factors that contributed to the cause of doses received during the operation.

Dose data obtained during or subsequent to an operation can be recorded in a preselected manner as part of a "Radiation Work Permit" or similar program (see Regulatory Position 3.1, Item 8) so that the data are amenable to statis-tical analyses.

Information concerning the cause of component failures that resulted in the need for servicing in high radiation areas can provide a basis for revising specifications on replacement equipment or for other modifications that can improve the component reliability.

Such improvements can reduce the frequency of servicing and thus reduce attendant exposures.

Information gained in operations can provide a basis for modifying equip-ment selection and design features of new facilities.

Summaries of doses received by each category of maintenance activity can be reviewed periodically by upper management to compare the incremental reduction of doses with the cost of station modifications that could be made.

4.

RADIATION PROTECTION FACILITIES, INSTRUMENTATION, AND EQUIPMENT A radiation protection staff with facilities, instrumentation, and protec-tive equipment adequate to permit the staff to function efficiently is an impor-tant element in achieving an effective program to maintain occupational radia-tion exposures ALARA.

The selection of instrumentation and other equipment and the quantities of such equipment provided for normal station operations should be adequate to meet the anticipated needs of the station during normal operations and during major outages that may require supplemental workers and extensive work in high radiation areas.

(Accident situations are not considered in this guide.)

Station design features and provisions should reflect the considerations identified below.

34

4.1 Counting Room A low-radiation background counting room is needed to perform routine analyses on station samples containing radioactive material collected from air, water, surfaces, and other sources.

An adequately equipped counting room would include the following equipment:

1.

A multichannel gamma pulse height analyzer (Regulatory Guide 5.9, "Specifications of Ge(Li) Spectroscopy Systems for Material Protection Measure-ments--Part 1:

Data Acquisition Systems," provides guidance for selecting Ge(Li) spectroscopy systems);

2.

Low-background alpha-beta radiation proportional counters or scintilla-tion counters;

3.

End-window Geiger-Mueller (G-M) counters; and

4.

A liquid scintillation counter for tritium analyses.

Analyses of bioassay and environmental samples and whole-body counting (see Regulatory Guide 8.9, "Acceptable Concepts, Models, Equations, and Assumptions for a Bio-assay Program") call for additional equipment and laboratory space if the analyses are performed by station personnel rather than by other specialists through contractual arrangements.

4.2 Portable Instruments Portable instruments needed for measuring dose rates and radiation charac-teristics would include:

1.

Low-range (nominally 0 to 5 R per hour) ion chambers or G-M rate meters;

2.

High-range (up to at least 104 R per hour) ion chambers; 1 5

3.

Alpha scintillation or proportional count rate meters;

4.

Neutron dose equivalent rate meters;

5.

Air samplers for short-term use with particulate filters (see ANSI N13.1-1969, "Guide to Sampling Airborne Radioactive Materials in Nuclear Facilities") 1 6 and iodine collection devices (such as activated charcoal cartridges); and 1 5 Variable alarm setpoint features on these instruments can be valuable in providing a warning when unexpected substantial changes in dose rate or air concentration occur.

1 6 See footnote 11 on page 25.

35

6.

7.

Air monitors with continuous readout features.

Beta measuring devices, either ion chambers or scintillation counters.

I 4.3 Personnel Monitoring Instrumentation Personnel monitoring instrumentation selection should include considera-tion of:

1.

2.

3.

4.

5.

6.

7.

8.

G-M "Friskers" for detecting low levels of radioactive material; Direct-reading low-range (0 to 200 mR) and intermediate-range (0 to 1000 mR) pocket dosimeters (see Regulatory Guide 8.4);

Alarm dosimeters; Film badges and thermoluminescence dosimeters (TLD);

Hand and foot monitors; Portal monitors; Personal air samplers; Automated TLD systems and computerized records systems.

4.4 Protective Equipment The selection of utility-supplied protective equipment should include con-sideration of:

1.

Anticontamination clothing and equipment that meet the requirements of ANSI Z88.2-1980, "Practices for Respiratory Protection,"' 1 7 for use in atmos-pheres containing radioactive materials or the National Institute of Occupational Safety and Health's (NIOSH)

"Certified Personal Protective Equipment List,"

and current supplements from the Department of Health and Human Services (formerly DHEW/PHS)

(Ref.

8).

2.

Respiratory protective equipment, including a respirator fitting program that satisfies the guidance of Regulatory Guide 8.15 and NUREG-0041.

4.5 Support Facilities Design features of radiation protection support facilities should include consideration of:

1 7 See footnote 11 on page 25.

36

1.

A portable-instrument calibration area designed and located so that radiation in the calibration area will not interfere with low-level monitoring or counting systems (see ANSI N323-1978, "Radiation Protection Instrumentation Test and Calibration" 18).

Calibration facilities should include the capability for calibrating air sampling instruments (see Regulatory Guide 8.25, "Calibra-tion and Error Limits of Air Sampling Instruments for Total Volume of Air Sampled").

2.

Personnel decontamination area with showers, basins, and installed "frisker" equipment.

This facility should be located and designed to expedite rapid cleanup of personnel and should not be used as a multiple-purpose area or share ventilation with food-handling areas.

3.

Facilities and equipment to clean, repair, and decontaminate personnel protective equipment, monitoring instruments, hand tools, electromechanical parts, or other material (highly contaminated tools or other equipment should not be decontaminated in the area used to clean respiratory equipment).

4.

Change rooms that connect with the personnel decontamination area and a control station area equipped with sufficient lockers to accommodate permanent and contract maintenance workers who may be required during major outages.

5.

Control stations for entrance or exit of personnel into radiation-and contamination-controlled access areas of the station such as the personnel entrance to the containment buildings and the main entrance to the radwaste processing areas; these control stations also may be used as the control point for radioactive material movements throughout the station and for the storage of portable radiation survey equipment, signs, ropes, and respiratory protec-tive equipment.

6.

Equipment to facilitate communication between all areas throughout the station.

7.

Sufficient office space to accommodate the temporary and permanent radiation protection staff, permanent records, and technical literature.

1 8 Available from ANSI (see footnote 11 on page 25) or the Institute of Electrical and Electronic Engineers, United Engineering Center, 345 East 47th Street, New York, New York 10017.

37

0. IMPLEMENTATION 0

This second proposed Revision 4 of the guide has been released to encourage public participation in its development.

Except in those cases in which an applicant has proposed an acceptable alternative method for complying with the criterion to maintain radiation exposure "as low as is reasonably achievable" of paragraph 20.1(c) of 10 CFR Part 20 of the Commission's regulations, the methods described in the currently active guide (Revision 3, June 1978) will continue to be used in the evaluation of submittals in connection with appli-cations for construction permits and operating licenses.

The methods to be described in the active Revision 4 reflecting public comments will be used in the evaluation of all license applications docketed after the implementation date to be specified in the active revision.

The implementation date will in no case be earlier than October 1982.

38

REFERENCES

1.

U.S. Department of Energy (DOE),

A Guide to Reducing Radiation Exposure to As Low As Reasonably Achievable (ALARA),

DOE/EV/1830-T5, April 1980.

Available from DOE, Washington, D.C.

2.

Ad Hoc Committee of the National Council on Radiation Protection and Mea-surements, "Somatic Radiation Dose for the General Population," Science, Vol.

131, pp. 482-486, February 19, 1960.

3.

National Academy of Sciences/Environmental Protection Agency, "The Effects on Populations of Exposure to Low Levels of Ionizing Radiation:

1980."

Available from National Academy Press, Washington, D.C.

4.

International Commission on Radiological Protection (ICRP),

"Implications of Commission Recommendations That Doses Be Kept As Low As Readily Achiev-able," ICRP Publication 22, 1973.

Available from Pergamon Press, Inc.,

Maxwell House, Elmsford, New York 10523.

5.

C. A. Pelletier et al., "Compilation and Analysis of Data on Occupational Radiation Exposure Experienced at Operating Nuclear Power Plants," Atomic Industrial Forum (AIF),

1974.

Available from AIF, 7101 Wisconsin Avenue, Washington, D.C.

20014.

6.

U.S. Nuclear Regulatory Commission, "Occupational Radiation Exposure at Commercial Nuclear Power Reactors, 1980," NUREG-0713, Vol.

2.*

7.

U.S. Nuclear Regulatory Commission, "Occupational Radiation Exposure, Eleventh Annual Report, 1978," NUREG-0593.*

8.

National Institute of Occupational Safety and Health, "Certified Personal Protective Equipment List," and supplements, July 1974.

Available from the U.S. Department of Health and Human Services, Division of Technical Services, 4676 Columbia Parkway, Cincinnati, Ohio 45226.

• NUREG-series reports are available at current rates through the GPO Sales Program, ATTN:

Sales Manager, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, or from the National Technical Information Service, Springfield, Virginia 22161.

39

DRAFT VALUE/IMPACT STATEMENT

1.

THE PROPOSED ACTION 1.1 Description The changes being made in this guide consist primarily of editorial improvements, updating of reference materials, and two technical additions.

The technical additions provide information on the design of a spent fuel transfer system and on maintenance of components using underwater techniques.

1.2 Need The revisions are being made to comply with the Nuclear Regulatory Commission's continuing effort to provide up-to-date information to the nuclear industry to ensure that occupational radiation exposures will be as low as is reasonably achievable (ALARA).

The proposed action is recommended because this guide has broad acceptance and usage in the nuclear industry and should be frequently updated to include new technical developments, methods, and positive operational experiences.

1.3 Value/Impact 1.3.1 NRC The proposed revision clarifies in several places the intent of the text using simplified language (editorial changes), provides up-to-date references, and broadens the technical scope of the guide as described above.

The revised portions of this guide continue to reflect current staff practices.

1.3.2.

Other Government Agencies Not applicable.

1.3.3.

Industry There should be no impact on the industry.

The added technical informa-tion will benefit the industry since it was gained from successful operating 40

experience at numerous nuclear facilities.

The value is in lower personnel exposure to radiation as well as time and labor savings.

1.3.4.

Public No significant impact on the public is foreseen.

1.3.5.

Radiation Workers Radiation workers will benefit as the collective occupational radiation exposure is reduced.

1.4 Decision on the Proposed Action Regulatory Guide 8.8 should be revised.

2.

TECHNICAL APPROACH The technical additions to the guide do not change or interfere with the previous contents of the guide; rather, the additions broaden the horizon of considerations for the design and operation of a nuclear facility in the effort to maintain occupational radiation exposures ALARA.

3.

PROCEDURAL APPROACH The proposed action is a comparatively minor revision of an existing regulatory guide for the purpose of keeping industry informed on current developments and good practices so that licensees not aware of these techniques may consider using them for the benefit of the workers.

No other procedural approach was considered.

4.

STATUTORY CONSIDERATIONS 4.1 NRC Authority Authority for this guide is derived from the Atomic Energy Act of 1954, as amended, and the Energy Reorganization Act of 1974, as amended, through the Commission's regulations.

41

4.2 Need for NEPA Assessment The proposed action is not a major action; thus an environmental impact statement will not be required.

5.

RELATIONSHIP TO OTHER EXISTING OR PROPOSED REGULATIONS OR POLICIES The revised guide reflects current regulatory practices; the technical additions are for consideration by nuclear power plant designers and operators, and no backfitting is anticipated.

42