I United States Department of Commerce

WZ3 1 National Institute ot Standards and Technology

NATL INST. OF STAND & TECH R.I.C. IBS

1 PUBLICATIONS 1

A111Q3 733b ciM ^ J

MSJ 5pm'a/ Publication 812

Criteria for the Operation of

Federally-Owned Secondary

Calibration Laboratories

(Ionizing Radiation)

E. H. Eisenhower, Editor
DATE DUE

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NIST Special Publication 812

Criteria for the Operation of

Federally-Owned Secondary

Calibration Laboratories

(Ionizing Radiation

)

E. H. Eisenhower, Editor

Office of Standards Code and Information

National Institute of Standards

and Technology

Gaithersburg, MD 20899

October 1991

U.S. Department of Commerce

Robert A. Mosbacher, Secretary

National Institute of Standards and Technology

John W. Lyons, Director
National Institute of Standards U.S. Government Printing Office

and Technology Washington: 1991

Special Publication 812

Natl. Inst. Stand. Technol.

Spec. Publ. 812

65 pages (Oct. 1991)

CODEN: NSPUE2

For sale by the Superintendent

of Documents

U.S. Government Printing Office

Washington, DC 20402
TABLE OF CONTENTS

Page

PREFACE iv

NOTE REGARDING UNITS vi

PART A - GENERAL CRITERIA . , 1

PART B - CALIBRATION OF SURVEY INSTRUMENTS 9

B.l - GAMMA-RAY CALIBRATION OF SURVEY INSTRUMENTS 9

B.2 - X-RAY CALIBRATION OF SURVEY INSTRUMENTS 12

B.3 - BETA-PARTICLE CALIBRATION OF SURVEY INSTRUMENTS 16

B.4 - NEUTRON CALIBRATION OF SURVEY INSTRUMENTS 20

B. 5 - ALPHA-PARTICLE CALIBRATION OF SURVEY INSTRUMENTS 24

PART C - IRRADIATION OF PERSONNEL DOSIMETERS 27

C. l - GAMMA-RAY IRRADIATION OF PERSONNEL DOSIMETERS 27

C.2 - X-RAY IRRADIATION OF PERSONNEL DOSIMETERS 30

C.3 - NEUTRON IRRADIATION OF PERSONNEL DOSIMETERS . . 33

C.4 - BETA-PARTICLE IRRADIATION OF PERSONNEL DOSIMETERS . ..... 36

PART D - GAMMA-RAY SOURCE CALIBRATION FOR EXPOSURE RATE 41

PART E - X-RAY CALIBRATION OF INSTRUMENTS FOR DIAGNOSTIC LEVELS ..... 43

PART F - CALIBRATION OF REFERENCE-CLASS INSTRUMENTS 47

F.l - GAMMA-RAY CALIBRATION OF REFERENCE-CLASS INSTRUMENTS ... 47

F.2 - X-RAY CALIBRATION OF REFERENCE-CLASS INSTRUMENTS 50

APPENDIX A - NIST PROFICIENCY TESTS 53

APPENDIX B - GLOSSARY OF TERMS 57

BIBLIOGRAPHY 61

i i i
PREFACE

This document contains standards of performance for laboratories that calibrate

instrumentation used to measure ionizing radiation. These standards may be used

as criteria on which a decision is based regarding accreditation of a particular

laboratory. Satisfaction of these criteria, along with any additional requirements imposed by an accrediting body, results in an accreditation that formally

acknowledges a demonstrated high level of competence.

These criteria were developed by a group of representatives of federally-owned

laboratories that perform the calibration functions addressed by this document.

As presented here, the criteria represent a consensus of those knowledgeable

individuals with regard to the actions and conditions necessary for the assurance of quality. Active participants in the preparation of these criteria, and

the laboratory or agency each represented at the time of participation, were

CPT Chip Adams

W. B. Austin

Joseph Balsamo

R. Douglas Carlson

William H. Casson

Frank Cerra

Lawrence F. Coldren

Jose Cortes

James D. Cross-Cole

Jan P. Cusimano

LTC Charles E. Day

Elwyn H. Dolecek

Elmer H. Eisenhower

Michael Eversole

William Ferrara

Kenneth C. Fertig

Steve Gargus

Thomas F. Gesell

Curtis L. Graham

Jerry Gray

Robert E. Halliburton

John S. Haynie

H. T. Heaton, II

CPT William V. Hoak

Tom Huynh

Stan Jones

Patrick Kuykendall

Ray LaBahn

Del Loney

Mike Martin

Donald Nell is

CPT James O'Brien

Thomas Ohlhaber

T. Jordan Powell

Kevin L. Reaves

Peter Roberson

Steven C. Rogers

MAJ Art Samiljan

Laboratory

Center

Center

Center

Air Force Occupational and Environmental Health

U.S. Navy, Naval Electronic Systems Engineering

Brookhaven National Laboratory

Idaho National Engineering Laboratory

Oak Ridge National Laboratory

Food and Drug Administration

Rocky Flats Plant

Federal Emergency Management Agency

U.S. Navy, Naval Sea Systems Command

Idaho National Engineering Laboratory

U.S. Army, Office of the Surgeon General

Argonne National Laboratory

National Institute of Standards and Technology

Portsmouth, Ohio Enrichment Facility

U.S. Navy, Naval Electronic Systems Engineering

U.S. Navy, Naval Electronic Systems Engineering

U.S. Air Force, Measurement Standards Laboratory

Idaho National Engineering Laboratory

Lawrence Livermore National Laboratory

U.S. Army, Primary Standards Laboratory

Oak Ridge National Laboratory

Los Alamos National Laboratory

Food and Drug Administration

Air Force Occupational and Environmental Health Laboratory

Federal Emergency Management Agency

Portsmouth, Ohio Enrichment Facility

U.S. Army, Primary Standards Laboratory

Primary Nucleonics Laboratory

Primary Standards Laboratory

Naval Electronic Systems Engineering

Nuclear Regulatory Commission

Air Force Occupational and Environmental

Food and Drug Administration

Lawrence Livermore National Laboratory

Oak Ridge National Laboratory

Pacific Northwest Laboratory

U.S. Army, Primary Standards Laboratory

U.S. Army, Office of the Surgeon General

U.S.

U.S.

U.S.

U.S.

Army

Army,

Navy, Center

Health Laboratory

i v
D. Michael Schaeffer

Carl J. Schopfer

Murari Sharma

Carl Siebentritt

C. Steve Sims

Kenneth L. Swinth

Charles R. Wallace

William H. Wilkie

William E. Wood

U.S. Navy, Naval Sea Systems Command

Brookhaven National Laboratory

U.S. Department of Energy

Federal Emergency Management Agency

Oak Ridge National Laboratory

Pacific Northwest Laboratory

U.S. Army, Primary Nucleonics Laboratory

Savannah River Site

U.S. Navy, Naval Electronic Systems Engineering Center

Although these criteria were developed by representatives of federally-owned

calibration laboratories, they are not limited to application in the federal

sector. Application in the state or private sectors is suitable also, and

would result in achievement of a similar high level of performance by those

laboratories.

The National Institute of Standards and Technology (formerly the National

Bureau of Standards) is actively supporting the development of a secondary

level of calibration laboratories for ionizing radiation measurements. Such

laboratories can provide a high-quality link between the physical measurement

standards maintained by NIST and those who make routine measurements at the

field level. Since the criteria contained in this publication represent a significant step in the development of a national system of secondary

laboratories, NIST is pleased to make them generally available for use.

v
NOTE REGARDING UNITS

It is the policy of NI ST to use the modern metric system of measurement units

(International System of Units; abbreviated as SI) in all publications. Units

used with the International System and units in use temporarily, as recognized

in NIST Special Publication 330, are acceptable. Included in those two

categories are the following units in this document:

Unit

Quantity Unit Name Symbol Value in SI units

time hour h 1 h

= 3600 seconds

energy electronvolt eV 1 eV == 1.602 x IO-1 9 joule (J)

exposure roentgen R 1 R

= 2.58 x 10 -1+ coulomb/kilogram

absorbed dose rad rad 1 rad = 10-2

g ray ( Gy ) dose equivalent rem rem 1 rem = 10-2 sievert (Sv)

Although use of the roentgen, rad, and rem is temporarily acceptable, a timely

transition to SI units is desirable. Therefore this document will show the SI

equivalent in parentheses wherever feasible.

The SI units indicated above will be shown for the quantities absorbed dose

and dose equivalent. However, since the quantity exposure is being phased out,

the SI unit coulomb/kilogram will not be shown in this document. It has no special name, it is inconvenient (especially for exposure rate), and its

definition is not consistent with other physical quantities. The quantity

exposure will be replaced with the quantity air kerma, which has the SI unit

joule/kilogram (J/kg) with the special name gray (Gy): 1 Gy = 1 J/kg.

Although the factor used for conversion from exposure in roentgens to air kerma

in grays depends slightly on photon energy, that variation is insignificant for

the purposes of this document and a single value will be used:

air kerma (in grays) = 0.00878 times exposure (in roentgens)

When a rounded value of exposure is given, the SI equivalent value of air kerma

will be rounded also (e.g., 10 mR/h * 90 yGy/h).

vi
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART A - GENERAL CRITERIA

1. INTRODUCTION

This document contains the criteria for accreditation of federally-owned

laboratories that calibrate ionizing radiation instrumentation (as defined

in the glossary). Adherence to these criteria will assure that the

laboratory is capable of high standards of performance in the calibration

of instrumentation for use in various radiation environments.

The criteria contained in Part A of this document shall be satisfied by

all laboratories seeking accreditation. In addition, each laboratory

shall satisfy the specific criteria contained in other parts of this

document for each category (radiation type and energy) for which

accreditation is desired.

2. LABORATORY MANAGEMENT AND STAFF

2.1 Management

The technical director of the laboratory shall have a position in the

organizational structure which assures the authority to conduct

laboratory operations free from any influence that could adversely

affect the quality or impartiality of the services offered. This

individual shall have a minimum of a bachelor's degree in physics,

engineering, health physics, or radiological physics, and should have

a graduate degree in one of these or a closely related scientific

field. This individual shall understand the laboratory protocol, be

responsible for assuring that it is being followed, and shall at

least annually evaluate staff competence and the need for training.

The laboratory technical director shall be responsible for

verification at least annually that documented procedures are

properly being followed and check the correctness of calibration of

individual instruments. A complete record of such checks shall be

maintained and available for audit.

The individual in charge of day-to-day operation of the laboratory

shall have at least 3 years of practical experience in radiation

measurement, including the calibration of radiation instrumentation.

2.2 Technical Staff

The technical staff employed in calibration work shall have

appropriate training or experience, be adequately supervised and

follow documented procedures. Each such individual shall understand

that responsibility for the correctness of a calibration lies with

the individual performing it.

1
3. PHYSICAL ASPECTS OF THE LABORATORY

3.1 Locatio n

The effect of external conditions on the internal environment of the

laboratory shall be considered in selection of the laboratory site.

The laboratory should be sited away from, or otherwise isolated from,

sources of mechanical vibration and shock, sources of electrical and

electromagnetic interference, and other potential sources of

interference with the proper calibration of instrumentation. If such

potential sources exist, the laboratory shall have documentation that

demonstrates no adverse effects on calibration accuracy.

3 .2 Envi ronment

Environmental monitoring equipment shall be provided for indicating

the temperature, atmospheric pressure, and humidity within the

laboratory at all times.

In general, strict temperature control is not essential for the

calibration work covered by these criteria. It is, however,

desirable that the laboratory be kept at reasonably uniform

temperature so that the accuracy of calibration is not adversely

affected and to ensure that an adequate level of stability is reached

before the start of calibration measurements. The laboratory

temperature should be maintained within the range of 20 to 24 °C.

When using a vented ionization chamber, the temperature shall not

vary more than ± 2 °C in any one hour during which a calibration is

conducted.

The relative humidity should be within the range of 15 to 65 percent

for routine laboratory operation.

The level of background radiation shall be maintained as low as

practicable and not subject to variations that could significantly

affect the accuracy of calibration work. Radiation sources not used

for calibration should not be stored in the radiation room.

3 .3 Servi ces

The electrical power shall be appropriate to the equipment used,

suitably stable, and free of switching surges and significant line

noise. When necessary, local auxiliary voltage stabilizers and

filters shall be provided.

The laboratory shall be provided with an adequate grounding system.

Where there is a likelihood of interference arising from equipment

connected to a single grounding system, separate grounding systems

shall be provided and adequate precautions taken against any possible

interconnection between systems.

If compressed air is used, a pressure regulator and means for

removing moisture, dust, and oil from the compressed air should be

provi ded.

2
4. CALIBRATION FACILITIES AND EQUIPMENT

4.1 Faci 1 ities

The laboratory shall have free-air conditions for all radiation beams

used for calibrations.

The radiation room (or rooms) shall be of sufficient size and design

that room-scattered radiation at the position where instrumentation

is normally placed for calibration does not introduce an error

inconsistent with overall accuracy goals. If necessary, proper

scatter corrections shall be applied.

4.2 Equi pment

The equipment available in the laboratory shall be appropriate to the

calibration services offered and the procedures employed in the

calibrations. Specific requirements for each service provided are

given in appropriate parts of this document.

No new equipment shall be put into service until it has been properly

checked and, where appropriate, calibrated.

The laboratory shall have secondary radiation measurement standards

that cover the range of calibrations performed. The secondary

standards should be used only for calibration of instruments and not

for any other purpose. A working standard should be used in lieu of

a secondary standard for routine reference.

The laboratory shall have a barometer capable of one percent

accuracy and a thermometer capable of t 1 °C accuracy. Each

have been calibrated by comparison with a tertiary or higher

standard. A hygrometer capable of monitoring over the range

relative humidity within which the laboratory operates shall

avai lable.

The laboratory shall have an instrument and radiation source

positioning system. The support shall be rigid and enable the

reproduction of a desired source/detector geometry. It shall produce

minimum scattered radiation.

All equipment used in the laboratory that was calibrated prior to the

initial accreditation of the laboratory, and all subsequent replacements for those items of equipment, shall be subject to a documented

program for quality control, and shall be recalibrated as necessary.

5. OPERATIONAL PROCEDURES

5.1 Laboratory Protocol

The laboratory shall have a written protocol. Each page of the

protocol shall indicate the date of inception or revision. The

protocol shall include the following:

shall

-1 evel

of

be

3
1. A statement of the scope of the laboratory's work, including all

of the radiation types, energies, and intensities for which calibrations are provided.

2. A statement of policy regarding acceptance of instrumentation for

calibration. Examples are policy regarding instruments that are

contaminated, in need of repair, or of a particular type not

accepted. Restrictions on type of customer or liability for

instrument damage should also be stated.

3. A statement of the laboratory's accuracy goals for the calibrations it performs. These accuracies shall be in terms of deviations

from a national standard.

4. A method of documenting the model and serial number of each

critical piece of equipment that is used in any calibration.

5. The procedure for calibrating each piece of laboratory support

equipment and a statement of the conditions under which recal i bration

is to be performed.

6. A fully documented procedure for each type of instrumentation

calibrated. The procedure shall provide the appropriate operational

steps to permit a knowledgeable person to reproduce a particular

calibration technique with a precision consistent with the accuracy

goals of the laboratory. Each calibration procedure shall give the

following information, as a minimum:

a. A concise but complete account of the procedure.

b. The scope and limitations of the procedure.

c. Any environmental constraints that must be met in calibrating

the instrumentation, in addition to those stated in 3.2.

d. The sequence of the calibration procedure, drawing attention

to special precautions.

e. The equipment and standards to be used in this calibration

procedure.

f. An example of a completed data sheet (or computer record) for

the calibrated instrumentation.

g. The method of data handling and reduction.

7. An assessment of the uncertainty associated with each calibration

procedure. The total systematic and total random uncertainties shall

be determined separately (at a specified confidence level) by

combining the individual systematic or random uncertainties in

quadrature. The total uncertainty shall be determined by combining

the total systematic and total random uncertainties, and the method

used for that combination shall be stated.

4
8. An example of a completed calibration report, including a statement of the accuracy to which the reference value of the radiation

field is known.

9. The procedure or reference for auditing calibration data and

approving reports.

10. The procedure to ensure the security of calibration records.

5 .2 Amendments to Procedures and Protocol

Any new or amended calibration procedure that could have a significant effect on the accuracy of a calibration shall be evaluated by

the accrediting body before it is adopted for routine use. A copy of

the latest revision of the laboratory's protocol shall be available

for audit at all times.

5.3 Notification of Mistakes

If the laboratory discovers a mistake in a calibration report that

significantly affects the accuracy of the calibration, the person or

institution that received the report shall be notified within

24 hours, if possible, and a written report of the mistake sent to

that person or institution within 72 hours. The mistake shall be

corrected as soon as possible by sending a corrected calibration

report or recalibrating the instrumentation. The laboratory shall

determine the reason for the mistake and take corrective action to

prevent its reoccurrence.

If the laboratory discovers an apparent generic error in one of its

procedures or in the design of an item of instrumentation that has or

could lead to an erroneous calibration, it shall notify the

accrediting body in writing within 10 days. Other accredited

laboratories may then be notified of the problem, along with

recommendations for remedial action.

6. ACCURACY AND QUALITY ASSURANCE

6.1 Calibration of Laboratory Standards

The standards or equipment originally calibrated by comparison with a higher-level standard shall be recalibrated when the need is

demonstrated by the results of proficiency testing or routine quality

control

6 .2 Accuracy of Services

The laboratory shall be capable of providing calibration services

with accuracies as indicated in the appropriate parts of this document. Each accuracy shall be stated in terms of percent deviation

from the national standard.

5
6.3 Quality Control

The laboratory's procedures shall be designed and operations

conducted to discover undesired changes in the performance of equipment on which the quality of a calibration depends. Such quality

control procedures, and the frequency of their use, shall be

specified in the laboratory's protocol.

The laboratory's proficiency shall be tested annually by the National

Institute of Standards and Technology (NIST) for those types of

calibrations provided by the laboratory. Each proficiency test shall

be representative of one or more types of calibration for which the

laboratory is accredited (see Appendix A). If the test results

indicate that corrective action is required, the laboratory shall

take action to achieve the accuracy stated in the appropriate part of

this document.

7. RECORDS AND REPORTS

7 .1 Record System

A comprehensive and readily available record system shall be maintained by the laboratory and shall include at least the following:

1. A full history and calibration data, including certificates, for

all standards and applicable calibration equipment.

2. An inventory of all standards and calibration equipment.

3. All procedures used for providing calibration services.

4. A bound day-book, or other equivalent record, in which is

recorded a description, sufficient for identification, of every item

of instrumentation for which a calibration service was provided and

the date that the calibration was performed. The day-book or other

record shall also include or reference a detailed report for that

specific calibration.

5. Information essential to the analysis and reconstruction of the

calibration of a specific item of instrumentation.

6. A record of routine quality control actions and any resultant

control charts.

7. Copies of all calibration reports issued.

8. The results of all proficiency testing.

9. Records detailing the education, experience, and training of all

operating staff and supervisory personnel.

All records of data shall identify the individual who collected the

data on which the record is based. Records for all individual items

of instrumentation calibrated shall be maintained for a period of at

6
least five years. Records regarding calibration of standards used

shall be maintained for a period of at least 50 years.

If calibration data are stored in a computer, the laboratory protocol

shall specify how backup is provided (i.e., data protection

procedures)

7 .2 Calibration Reports

A calibration report shall be issued for each item of instrumentation

calibrated under the scope of accreditation, including an appropriate

statement clearly specifying the conditions (e.g., orientation of the

detector) under which the calibration was performed. It should also

state limitations to the calibration, i.e., maximum range calibrated

if less than the indicated range of an instrument, scales not

calibrated, application of correction factors, etc.

The uncertainty associated with the calibration shall be stated.

Calibration reports shall be reviewed for technical accuracy and

shall be signed by the laboratory technical director or designated

alternate.

7

CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART B - CALIBRATION OF SURVEY INSTRUMENTS

PART B.l - GAMMA-RAY CALIBRATION OF SURVEY INSTRUMENTS

1. INTRODUCTION

The criteria contained in this part apply to the calibration of health

physics instruments at radiation protection levels using one or more

gamma-ray sources. These criteria are supplementary to the general

criteria contained in Part A. Both the general criteria and these

specific criteria shall be followed if this gamma-ray calibration service

is offered and its inclusion in the Scope of Accreditation is desired.

2. SOURCES OF GAMMA RADIATION

One or more of the following radiation sources shall be available for use

in the calibration of health physics instruments:

The radiation fields produced by the sources shall cover a range of

exposure (air kerma) rates suitable for protection-level calibration. A

minimal range is 1 mR/h to 5 R/h (9 uGy to 40 mGy/h); and, a more

desirable range is 0.5 mR/h (4 pGy/h) to at least 100 R/h (0.9 Gy/h).

3. RADIATION CONTROL

3.1 Shielding

Radiation barriers and/or storage containers for sources shall

provide sufficient shielding so that radiation added to natural

background radiation in the calibration area is sufficiently low as

to not interfere with ongoing calibration work. Added background

radiation and leakage radiation from all sources in the calibration

area should not contribute more than 1 percent of the total exposure

(air kerma) rate at which an instrument is calibrated.

3.2 Beam Collimation

The gamma radiation beam emitted from a source that has been exposed

for calibration shall be collimated so that its size is limited to

an area consistent with calibration requirements. An exception to

this requirement is calibration facilities sufficiently large to

provide a low room-scatter radiation environment for instrument

calibration, e.g., an uncollimated source in a low scatter room.

Radi onucl i de Nominal Energy

2*1 Am

137Cs

60Co

60 keV

660 keV

1.26 MeV

9
3.3 Source Exposure

The source storage container shall have a mechanism to control

exposure in the gamma beam. If the radiation source is used for

calibration of exposure (air kerma) measuring (as contrasted with

exposure-rate (air kerma-rate) measuring) instruments, the shutter

or source transit time and its effect on the total radiation

exposure (air kerma) shall be known.

3.4 Exposure Control

If the radiation source is used for the calibration of exposure (air

kerma) measuring instruments (see 3.3, above), the shutter or source

transfer shall be initiated and terminated by a timer or the

exposure (air kerma) shall be controlled by use of a transmission

chamber. Any associated systematic timing uncertainties shall be

documented and eliminated or compensated.

4. EQUIPMENT

In addition to one or more radiation sources and associated control

devices, the laboratory shall have as a minimum the following equipment:

a. Secondary standard ionization chambers suitable for the photon energy

and intensity ranges for which calibration services are offered.

b. An electrometer to measure the charge produced in the ionization

chambers.

c. A voltage source suitable for chamber polarizing potential.

d. An independent measuring system for verification of the performance

of the secondary standard ionization chambers and electrometer.

e. An instrument and ionization chamber support and positioning system.

The system should provide for reproducible and accurate positioning of an

instrument or chamber with respect to the radiation source. For beam

type irradiation configurations, the positioning system should define the

central axis of the gamma beam.

Additional equipment should include a pulse generator, oscilloscope,

current source, precision capacitors and precision resistors.

"5. CHARACTERIZATION OF THE RADIATION FIELD

S.l Exposure Rate (Air Kerma Rate)

The gamma radiation field used

ized in terms of exposure (air

distance from the source. The

known at each distance used.

for calibration shall be characterkerma) rate at a given position or

exposure (air kerma) rate shall be

10
5.2 Scattered Radiation

The effect of room-scattered radiation (relative to a radiation

field with minimal room scatter) on the accuracy of calibration of

each instrument type shall be known at each location where a detector is placed for instrument calibration.

5.3 Attenuation

If an attenuator is used to reduce the exposure (air kerma) rate at

any location in the radiation field, the effect of the altered

radiation spectrum (relative to an unattenuated radiation spectrum)

on the accuracy of calibration of each instrument type shall be

known. The approximate energy spectrum of the attenuated radiation

field should be known. Secondary electron equilibrium at the

calibration position shall be documented.

5.4 Accuracy

The exposure (air kerma) rate specified by the laboratory as its

reference value for each source of radiation shall be within

5 percent of the true value as defined by comparison with a national

standard above 10 mR/h (90 yGy/h) , and within 7 percent of the true

value from 0.5 mR/h (4 yGy/h) to 10 mR/h (90 yfiy/h). This level of

agreement with the standard shall be demonstrated through periodic

proficiency testing by NIST. A description of the proficiency test

is given in Appendix A.

CALIBRATION REPORT

An instrument calibration report shall include, as a minimum, the radionuclide or photon energy used, the reference exposure (air kerma) rate or

rates at which the instrument was calibrated, the exposure (air kerma)

rate indicated by the instrument, and the correction factor at each

calibration point. In the case of integrating instruments, in addition

to the radionuclide and exposure (air kerma) rate, the reference

exposure (air kerma), instrument reading, and correction factor shall be

included. At least one calibration point should be included for each

range of the instrument, where applicable. The orientation of the

instrument with respect to the radiation beam shall be described or

illustrated in the calibration report, and the use of a build-up cap

shall be noted. For instruments that use a vented ionization chamber,

the reported values shall be referenced to a temperature of 22 °C and a barometric pressure of 760 mm Hg, and the equation needed to convert to

other temperatures and pressures shall be provided.

11
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART B.2 - X-RAY CALIBRATION OF SURVEY INSTRUMENTS

1. INTRODUCTION

The criteria contained in this part apply to the calibration of health

physics instruments at radiation protection levels using an x-ray source.

These criteria are supplementary to the general criteria contained in

Part A. Both the general criteria and these specific criteria shall be

followed if this x-ray calibration service is offered and its inclusion

in the Scope of Accreditation is desired.

Criteria for calibration of instruments for diagnostic levels using an

x-ray source are contained in Part E.

2. SOURCE OF X RAYS

A constant potential x-ray generator shall be available for use in the

calibration of health physics instruments. Its maximum ripple shall not

exceed 2 percent and it should be operable over a minimum range of 30 to

150 kV, 1 to 10 mA.

3. CONTROL OF THE RADIATION BEAM

3.1 Radiation Production

The production of a useful beam of radiation may be by means of the

application of high voltage to the x-ray tube or the opening of a mechanical shutter (which normally acts as a shield to the x-ray

beam)

.

3.2 Beam Collimation

The x-ray beam emitted from the tube housing shall be collimated so

that its size is limited to an area consistent with calibration

requirements. Provision shall be made for identifying the central

axis, and the boundaries of the useful area of the beam shall be

known.

3.3 Exposure Control

If the radiation source is used for the calibration of exposure (air

kerma) measuring instruments, the radiation beam shall be controlled

by a timer or the exposure (air kerma) shall be controlled by use of

a transmission chamber. The timing error due to the shutter transit

times or high voltage ramping shall be known.

12
4. EQUIPMENT

In addition to one or more x-ray machines and associated control devices,

the laboratory shall have the same minimum equipment as that required for

gamma ray calibration (see Part R.l, Section 4) with the following

exception - the secondary standard ionization chambers shall be

appropriate to the energy and intensity of x rays for which calibration

services are offered.

Additionally, the laboratory shall be equipped with filters to permit the

production of a variety of x-ray beam qualities (see paragraph 5.3,

bel ow)

5. CHARACTERIZATION OF THE RADIATION FIELD

5.1 Exposure Rate (Air Kerma Rate)

The x-ray radiation field used for calibration shall be characterized in terms of exposure (air kerma) rate at a given position or

distance from the anode of the x-ray tube. The exposure (air kerma)

rate shall be known at each distance used. During calibration of an

instrument, the exposure (air kerma) rate shall not vary by more

than 2 percent from the nominal rate when it is 10 mR/h (90 yGy/h)

or higher, and shall not vary by more than 4 percent from the

nominal rate when it is below 10 mR/h (90 yGy/h).

5.2 Scattered Radiation

The effect of room-scattered radiation (relative to a radiation

field with minimal room scatter) on the accuracy of calibration of

each instrument type shall be known at each location where a detector is placed for instrument calibration.

5.3 Radiation Duality

The x-ray beam emitted from the tube housing shall be filtered

before use to provide the appropriate radiation quality for calibration purposes. If a transmission chamber is used for routine beam

monitoring, it shall be considered to be added filter material.

Three or more of the beams shown in table 1 shall be available.

The first half-value layer and homogeneity coefficients for a given

x-ray beam shall be within 5 percent, and 7 percent, respectively,

of the values shown in table 1. If necessary the indicated tube

voltage or added filter, or both, may be adjusted to achieve those

values.

The intensity of the x-ray beam shall not vary more than 5 percent

across the useful area of the beam.

The radiation quality shall be checked for stability at least

annually. Whenever any part that could affect the beam quality is

repaired or replaced the above requirements for radiation quality

shal 1 be met.

13
5.4 Accuracy

The exposure (air kerma) rate specified by the laboratory as its

reference value for each x-ray beam shall be within 5 percent of the

true value as defined by comparison with a national standard above

10 mR/h (90 yGy/h). and within 7 percent of the true value from

0.5 mR/h (4 yGy/h) to 10 mR/h (90 yGy/h). This level of agreement

with the standard shall be demonstrated through periodic proficiency

testing by NIST. A description of the proficiency test is given in

Appendix A.

CALIBRATION REPORT

An instrument calibration report shall include, as a minimum, the x-ray

beam used for calibration, the reference exposure (air kerma) rate or

rates at which the instrument was calibrated, the exposure (air kerma)

rate indicated by the instrument, and correction factor at each

calibration point. In the case of integrating instruments, in addition

to the x-ray beam and exposure (air kerma) rate, the reference exposure

(air kerma), instrument reading, and correction factor shall be included.

At least one calibration point should be included for each range of the

instrument, where possible. The orientation of the instrument with

respect to the radiation beam shall be described or illustrated in the

calibration report. For instruments that use a vented ionization

chamber, the reported values shall be referenced to a temperature of

22 °C and a barometric pressure of 760 mm Hg, and the equation needed to

convert to other temperatures and pressures shall be provided.

14
TABLE 1. Characteristics of X-Ray Beams

Critical Characteristics® Relevant information®

Half-Value Layer Homogeneity Added Filter Effective Distance

Beam Coefficient Energy

Code Al Cu A 1 Al Cu Al Cu on raw rb

(mm) (mm) (mm) (mm) (mm) (mm) (keV) (cm)

L10 0.029 79 0 95

T K 0.050 74 ft

T "5ft 0.071 76 ft 50

T 1ft 0.22 60 0 965 50

T Aft 0.49 57 0 50 50

T 5ft 0.75 58 0 639 50

TLOU8ft 1.83 58 1 284 50

T Iftft 9 8 59 1l«7/0 978 50

0.152 79 0.230 50

M30 0.36 64 0 50 50

M40 0.73 66 0 786 50

JVUU 1.02 0.032 66 62 1 091 50

JVIOU 1.68 0.052 68 64 1 51

Ayflftft 5.0 0.20 72 55 5 0

\/f 1 5ft 10.2 0.67 87 62 5 0 0.25

'M'Oftft 14.9 1.69 95 69 4 1 1.12

TV/f)^ft ivizju 18.5 3.2 98 86 5 0 3.2

22. 5.3 100 97 4 0 6.5

win ft rids 89 0.105 25

HI 5 0.152 87 0.500 25

H90 0.36 88 1.021 50

H30 1.23 0.038 93 94 4.13 50

H40 2.9 0.093 94 95 4.05 0.26 50

H50 4.2 0.142 92 90 4.0 0.10 38

H60 6.0 0.24 94 89 4.0 0.61 46

H100 13.5 1.14 100 94 4.0 5.2 80

H150 17.0 2.5 100 95 4.0 4.0 1.51 120

H200 19.8 4.1 100 99 4.0 0.60 4.16 0.77 166

H250 22 5.2 100 98 4.0 0.60 1.04 2.72 211

H300 23 6.2 99 98 4.1 3.0 5.0 252

^^The half-value layer and homogeneity coefficient shown for a beam shall be matched by the

laboratory within limits prescribed by pertinent parts of these criteria. In the beam code, the letter

indicates light, moderate, heavy filtration, and the number is the constant potential in kilovolts.

^^This information relates specifically to the NIST beams, and may provide useful guidance to a

laboratory that is seeking accreditation. The inherent filtration of the NIST beams is approximately

1.0 mm Be for beam codes L10-L100, M20-M50, H10-H40, and

3.0 mm Be for beam codes M60-M300, H50-H300.

15
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART B.3 - BETA-PARTICLE CALIBRATION OF SURVEY INSTRUMENTS

1. INTRODUCTION

The criteria contained in this part apply to the calibration of health

physics instruments at radiation protection levels using a beta particle

source. These criteria are limited to the calibration of instruments

used to measure dose rate from external beta sources and are supplementary to the general criteria contained in Part A. Both the general

criteria and these specific criteria shall be followed if this betaparticle calibration service is offered and its inclusion in the Scope of

Accreditation is desired.

2. SOURCE OF BETA PARTICLES

The selection of a source for beta particle calibration of an instrument

will depend both on the nature of the radiation field in which the

instrument is to be used and the anticipated energy of the beta radiation. It is recommended that both point sources and distributed sources

be available for instrument calibration since they represent the extremes

of measurement geometry. The radionuclides listed in table 2 are

recommended for use as reference sources for beta calibration; however,

other sources may be used if they more accurately represent the beta

energy spectrum in which the calibrated instrument is to be used.

The laboratory shall have at least the following radionuclide sources of

beta particles:

i*7 Pmj 20*71 , and 90 Sr/Y.

These sources shall comply with the ISO 6980 standard.

TABLE 2. Characteristics of Beta-Particle Sources

Radi onucl ide E

max ( keV ) Half-Life

(years)

i^Pm (a) 225 2.62

99TC 290 ~ 2x105

85Kr 670 10.8

36C1 710 ~ 3x105

2 04J1 763 3.8

9°Sr/Y (b) 2270 28.6

Natural II 2290 ~ 4x109

Depleted U 2290 ~ 4x109

106R U /Rh 3640 1.0

(a) i'+7 Pm usually also contains i^Pm, which has an E max

= 780 keV.

(b) The source should be sealed with 100 mg/cm 2 (nominal) filtration to

remove the 90 Sr beta component.

16

i
3. RADIATION BEAM CONTROL AND PARAMETERS

3.1 Radiation Production

The production of a beam (field) of beta radiation for instrument

calibration may be achieved by means of a shutter exposing the

source or by moving the source to an exposed position.

3.2 Ream Parameters

The physical size of the beta ray beam (field) shall have been

predetermined to assure that it is sufficiently large to accommodate

the instrument being calibrated. Provision shall be made for

identifying the central axis, and the boundaries of the useful area

of the beam shall be known. If necessary, beam flattening filters

may be used to meet the requirements of paragraph 5.4.

3.3 Timer

If the radiation source is used for the calibration of fluence

measuring instruments, the radiation beam shall be controlled by a timer. The timing error due to the shutter transit times shall be

documented and eliminated or compensated.

4. EQUIPMENT

In addition to an appropriate selection of beta particle sources, the

laboratory shall have the same minimum equipment as that required for

gamma ray calibration (see Part B.l, Section 4); however, in this case

the secondary standard ionization chamber shall be a thin-window fixed

volume ionization chamber or an extrapolation chamber. The extrapolation

chamber or thin-window ionization chamber response shall have been

verified by the NIST or by comparison to NIST or PTB calibrated beta

radiation sources and have an accuracy equivalent to that described in

paragraph 5.5, below, over the anticipated range of irradiation

conditions, i.e., beta energy and depth of dose measurement point.

5. CHARACTERIZATION OF THE BETA RADIATION FIELD

5.1 Dose Rate

The beta radiation fields used for calibration shall be

characterized in terms of absorbed dose rate (at a depth in tissue

of 7 mg/cm 2

) at a given position or distance from the source. The

dose rate shall be known at each distance used. Similarly, if

calibrations are to be done at other tissue depths (for example, at

300 mg/cm 2 to simulate exposure of the lens of the eye, rather than

7 mg/cm 2 for the skin), then the dose rate at these depths shall be

known.

17
5.2 Attenuation

In order to assure that the energy of the beta radiation that

reaches the detector is similar to that originating from the

radionuclide, certain limits on the calibration conditions are

recommended. If E_

es refers to the residual maximum energy of a beta particle reaching the detector of an instrument and E

max

is

the energy at which the beta particle originates, then the

conditions shown in table 3 should be met.

TABLE 3. Limiting Conditions for Beta Particles

LE E /E max I-res /cmax

<100 keV > 0.6

100 - 800 keV > 0.7

>800 keV > 0.8

These conditions are recommended so that no undue attenuation from

the source's self-absorption, containment, beam flattening filters,

or air attenuation will significantly change the radionuclide's beta

spectrum. The procedure for determining E is given in the

ISO 6980 standard.

5.3 Contamination

In addition to the radiation quality considerations on which the

preceding paragraphs impact, source contamination by other

radionuclides may significantly change the beta or gamma radiation

field from a source. Small levels of beta contamination are

difficult to detect but fortunately are usually accompanied by gamma

contamination. The beta spectral purity is considered adequate if

the following hold:

1. The plot used to measure R

pes

has a linear section, and;

2. The E

pes

value meets the criteria in table 3.

For requirement 1 above, R

pes

is the range in an absorbing material

of a beta spectrum of residual maximum energy, E re

_. The procedure

for measurement of R res

is given in the ISO 6980 standard.

Measurement to determine the adequacy of beta spectral purity shall

be made every 2 years, or more often if needed.

Photon contamination of the beta field due to sources of gamma,

x-ray, and bremsstrahl ung radiation should contribute less than

5 percent of the total absorbed dose.

18
5.4 Uniformity of Beta Field

The beta dose rate should be uniform over the area of the detector

face. The dose rate across the beam profile at a depth of 7 mg/cm 2

should not vary more than 5 percent from the mean dose rate for E

res

greater than or equal to 300 keV, and not more than 10 percent for

E

pes

less than 300 keV. The uniformity of the beta field shall be

verified by measurement with a small area detector or film.

5.5 Accuracy

The dose rate specified by the laboratory as its reference value for

each beta-particle beam shall be within 10 percent of the true value

as defined by comparison with a national standard. This level of

agreement with the standard shall be demonstrated through periodic

proficiency testing by NIST. A description of the proficiency test

is given in Appendix A.

CALIBRATION REPORT

An instrument calibration report shall include, as a minimum, the

radionuclide and radiation field type (point source or flat field) used

for calibration, the reference dose rate or rates at which the instrument

was calibrated, and the dose rate (or dose) indicated by the instrument

at each calibration point. The orientation of the instrument with

respect to the radiation beam shall be described or illustrated in the

calibration report. The report should state whether the front face or

the effective center of the detector was located at the point where the

reference field was characterized.

19
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART B.4 - NEUTRON CALIBRATION OF SURVEY INSTRUMENTS

1. INTRODUCTION

The criteria contained in this part apply to the calibration of health

physics instruments at radiation protection levels using neutron

radiation. These criteria are supplementary to the general criteria

contained in Part A. Both the general criteria and these specific

criteria shall be followed if this neutron radiation calibration service

is offered and its inclusion in the Scope of Accreditation is desired.

2. SOURCE OF NEUTRON RADIATION

The selection of a source for neutron radiation calibration of an

instrument will depend on the nature of the radiation field in which the

instrument is to be used, including the anticipated neutron energy

spectrum. The neutron sources described in table 4 are frequently used

for instrument calibration.

As a minimum, a laboratory shall have at least one of the sources shown

in table 4 with appropriate strength for the dose equivalent or dose

equivalent-rate range of the instruments to be calibrated. A minimum

dose equivalent rate range is 10 mrem/h to 1 rem/h (0.1 to 10 mSv/h).

The neutron source strength shall be certified by or traceable to the

NIST. If a 252Qf source is used, the laboratory shall be capable of

calibrating an instrument using both the bare source and the moderated

configuration.

TABLE 4. Characteristics of Commonly Used Fast Neutron Sources For

Calibration of Neutron Survey Instruments (Lorenz, 1972)

Source

Method of

Neutron Production

Neutron Energy (MeV)

Half-life Max. Average

238pu (Be)

239p u (Be)

2<+iAm (Be)

252Cf

252Cf

15

Moderated with

cm D

20 (e.g.

,

Schwartz, 1980;

Prevo, 1983)

(a,n)

(a,n)

(a,n)

SF

SF

86.4 Y 11.3

24390 Y 10.74

458 Y 11.5

2.654 Y 15

2.654 Y 15

5.0

4.5-5

5.0

2

0.54

The radiation field produced by a neutron source used for calibration

shall provide an energy spectrum and dose equivalent rates appropriate

for the instrument undergoing calibration.

20
3. RADIATION CONTROL AND PARAMETERS

3.1 Radiation Production

The production of a field of neutron radiation for instrument

calibration should be achieved by moving the source from a shielded

to an exposed position, preferably in a low-scatter environment in

an open area or at the center of a large room (for example, 10x10

meters square with the source 4 m from both floor and ceiling). The

neutron radiation field used for calibration shall be carefully

monitored and controlled. The response due to room-scattered

neutrons at the point of calibration should be less than 25 percent

of the total instrument response, and the appropriate corrections

shall be made.

If the neutron source is used for the calibration of integrated dose

equivalent measuring instruments, the radiation field shall be

controlled by a timer. Any associated systematic timing uncertainties shall be documented and eliminated or compensated.

4. EQUIPMENT

In addition to a selection of one or more neutron sources appropriate to

the radiation field(s) for which instruments are being calibrated, the

laboratory shall have the same minimum equipment as that required for

gamma-ray calibration (see Part B.l, Section 4), with the exception of

secondary standard ionization chambers and that equipment associated with

their use. An instrument of each type calibrated should be available for

the measurement of the contribution of scattered radiation to the total

instrument response.

5. CHARACTERIZATION OF THE NEUTRON RADIATION FIELD

5.1 Dose Equivalent Rate

The neutron radiation field used for calibration shall be characterized in terms of the flux density (fluence rate) and spectral

composition at the point of calibration. The dose equivalent rate

shall be calculated on the basis of these characteristics (see

table 5) as a means of setting calibration points for specific

instrument types.

5.2 Radiation Quality

In addition to the radiation quality considerations on which the

preceding paragraphs impact, contamination of the neutron field by

other types of radiation may contribute to instrument response. If

this is the case and the instrument is sensitive to photon and/or

beta radiation as well as neutrons, the extent of this contamination

shall be known and corrected for when calibrating a given instrument. Photon contamination of the neutron field shall be known and

should be less than 20 percent of the total dose equivalent rate.

3.2 Timer

21
TABLE 5. Characterization of neutron sources in terms of dose equivalent

Radionucl ide

source

Mean neutron fluence

to dose equivalent . conversion factor^ 3 '

rem cm 2

Specific

source

strength

Specific neutron

dose equivalent

rate at 1 m^°>

s-i . Ci _1 mrem . h~i . Ci _1

238p u (Be)

239p u (Be)

24

1

Am( Be) 3.8 x 10-8

2.0 x 106

1.5 x 106

2.4 x 10 6 2.7

s~ 1 » mg- 1 mrem • h

-

1

» mg~ 1

252Cf

252Cf moderated

3.4 x 10-8

9.1 x 10-9

2.4 x 10 9

2.1 x 109

2.3 x 103

5.4 x 102

aThe conversion factors were calculated from -5- f B c

h (E)dE, where B is the

0

E

+ neutron source strength, B^ is the spectral distribution of neutron source

strength, and h is the neutron fluence to dose equivalent conversion factor,

i.e., the quotient of the dose equivalent and the neutron fluence, ~

(Reference: ISO 8529 (1989)) (1 rem = 0.01 Sv).

bThese are typical numbers. Dose equivalent rate from a particular source

depends upon variable factors such as purity, internal absorption,

construction details, and encapsulation (1 mrem = 0.01 mSv).

22
5.3 Accuracy

The dose equivalent rate specified by the laboratory as its

reference value for each neutron field shall be within 10 percent of

the true value as defined by comparison with a national standard.

This level of agreement with the standard shall be demonstrated

through periodic proficiency testing by NIST. A description of the

proficiency test is given in Appendix A.

CALIBRATION REPORT

An instrument calibration report shall include, as a minimum, the radionuclide and radiation field type (moderated or unmoderated) used for

calibration, the free-field dose equivalent rate or rates at which the

instrument was calibrated, the scatter-corrected instrument reading at

each calibration point, and the basis for any calculation of dose

equivalent rate from source emission rate. At least one calibration

point should be included for each decade range of the instrument, where

possible. The orientation of the instrument with respect to the

radiation field shall be described or illustrated in the calibration

report. The value of the scatter correction shall be provided.

23
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART B.5 - ALPHA-PARTICLE CALIBRATION OF SURVEY INSTRUMENTS

1. INTRODUCTION

The criteria contained in this part apply to the calibration of survey

instruments at radiation protection levels using alpha radiation sources.

These criteria are supplementary to the general criteria contained in

Part A. Both the general criteria and these specific criteria shall be

followed if this alpha-particle calibration service is offered and its

inclusion in the Scope of Accreditation is desired.

2. SOURCE OF ALPHA RADIATION

Planar or pseudo planar alpha radiation sources shall be used for the

purpose of calibrating instruments used for the detection of alpha

contamination. A pseudo planar source is one made up of a closely spaced

array of small sources. The combined thickness of the source media and

overburden shall be less than one-tenth the range of the least energetic

alpha particle in these media. Only the following thin sources of alpha

radiation are acceptable provided their 2n alpha emission rate (per unit

area) is known and traceable to a source calibrated by the National

Institute of Standards and Technology.

1. Natural or depleted uranium.

2. Plutonium-238 or -239.

3. Natural thorium or thorium-230.

The radiation fields produced by the sources shall cover a range of at

least three decades of alpha emission rates suitable for protection-level

calibration. A recommended range is 100 alpha particles per minute (2tt

emission rate) to 10 6 alpha particles per minute.

3. RADIATION CONTROL

3.1 Source Exposure

Because of the short range of alpha particles in air, calibration

measurements using an alpha source shall be made in such a way that

the alpha radiation emitted from the source reaches the sensitive

volume of the radiation detector. To assure that this is the case,

there should be no shielding materials between the alpha source and

the detector, other than that inherent to the detector or source

itself. Additionally, the surface of the radiation detector should

be no further than 3 mm from the surface of the alpha radiation

source.

4. EQUIPMENT

In addition to radiation sources, the laboratory shall have as a minimum

the following equipment:

24
(1) A source and detector support and positioning system. The system

shall provide for reproducible and accurate positioning of a detector

with respect to the radiation source.

(2) An independent measuring system used as a means of checking the

sources for any degradation of their alpha emission rate.

5. CHARACTERIZATION OF THE RADIATION FIELD

5.1 Emission Rate

The source used for calibration shall be characterized in terms of

the alpha emission rate per unit area. The boundary of the source

shall be greater than that of the detector. The relative standard

deviation of the emission rate averaged over every individual

segment of the source shall be less than ± 6 percent. The maximum

area of a segment shall be 10 cm 2

, and a segment shall not exceed

10 percent of the total surface area of the source. The spacing of

smaller sources to form a pseudo array shall be such that the pointto-point distance between sources is less than the range of alpha

radiation in air.

5.2 Accuracy

The alpha emission rate specified by the laboratory as its reference

value for each source of radiation shall be within 10 percent of the

true value as defined by comparison with an appropriate standard

traceable to the NIST. This level of agreement with the standard

shall be demonstrated through periodic proficiency testing by NIST.

A description of the proficiency test is given in Appendix A.

6. CALIBRATION REPORT

An instrument calibration report shall include, as a minimum, the alpha

radiation source used for calibration, the emission rate or rates at

which the instrument was calibrated, and the instrument response at each

calibration point. At least one calibration point and a linearity check

should be included for each range of the instrument, where applicable.

25
t
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART C - IRRADIATION OF PERSONNEL DOSIMETERS

PART C.l - GAMMA-RAY IRRADIATION OF PERSONNEL DOSIMETERS

1. INTRODUCTION

The criteria contained in this part of the document apply to irradiation

of dosimeters at radiation protection and accident levels (as defined in

ANSI N13.ll) using gamma-ray sources. These criteria are supplementary

to the general criteria contained in Part A, and shall be followed if

this specific irradiation service is offered and its inclusion in the

Scope of Accreditation is desired. In that case, both the general

criteria and these specific criteria shall be followed.

2. SCOPE

These criteria apply to irradiation of dosimeters used for personnel

monitoring. They do not apply to dosimeters used for high-level

dosimetry in applications such as radiation processing or sterilization.

3. SOURCE OF GAMMA RADIATION

One or more 137Cs source(s) of gamma rays shall be available for

irradiation services. The radiation fields produced by the sources shall

cover a range of exposures (air kerma) suitable for protection-level

irradiations. The range covered will be a function of the mission and

requirements of the laboratory but 30 mR to 500 R (0.3 mGy to 4 Gy) will

suffice for most radiation protection purposes.

4. CONTROL OF RADIATION BEAM

4.1 Shielding

Source storage containers shall provide sufficient shielding such

that leakage radiation does not interfere with other uses of the

radiation room by raising the background level. Background

radiation and leakage radiation from all sources in the radiation

room shall not contribute more than 0.1 percent of the total

exposure (air kerma) to which dosimeters are irradiated.

4.2 Beam Size and Uniformity

The gamma beam emitted from the irradiator should be collimated so

that its size is limited to the minimum area consistent with irradiation requirements. All dosimeters shall be irradiated with phantom

backing, and the beam size shall be sufficient to irradiate the

entire phantom surface that is facing the source. If several

dosimeters are irradiated simultaneously, the beam shall be

sufficiently uniform and characterized to satisfy the requirements

of section 6.3.

27
4.3 Beam Emission Control

The irradiator shall have a built-in device to control emission

of the gamma beam. It shall be possible to operate the emission

control device with a timer. Any associated random timing

uncertainties due to transit time of the device shall be known. Any

associated systematic timing uncertainties shall be measured and

eliminated or compensated.

5. EQUIPMENT

In addition to radiation source(s) and the associated beam control

devices, the laboratory shall have the same minimum equipment as that

required for gamma-ray calibration (see Part B.l, Section 4), plus the

fol lowing:

(1) Secondary standard ionization chambers that are calibrated for 137Cs

gamma rays and that cover the exposure (air kerma) rate ranges used

for irradiation services.

(2) A phantom consisting of a slab of polymethylmethacrylate with a minimum cross section of 30 x 3D cm and a thickness of 15 cm. The

support system for the phantom shall be rigid and produce minimum

scattered radiation at the dosimeter position(s).

6. CHARACTERIZATION OF THE RADIATION FIELD

6.1 Exposure Rate (Air Kerma Rate)

The gamma radiation field used for irradiation shall be characterized in terms of exposure (air kerma) rate in the absence of a phantom at the location where the center of the front surface of the

phantom is placed for irradiation.

6.2 Scatter

The contribution from room-scattered radiation shall be determined

with the phantom removed from the beam and shall not exceed

5 percent of the exposure (air kerma) rate at any location where a dosimeter is placed for irradiation. The approximate energy

spectrum of room-scattered radiation should be known.

The relationship between shallow dose and deep dose shall be

measured for each facility because the charged particle surplus or

deficit is highly dependent on local scattering conditions.

6.3 Accuracy

The exposure (air kerma) rate specified by the laboratory as its

reference value shall be within 3 percent of the actual value

defined by comparison with the national standard. This level of

agreement with the national standard shall be periodically verified

through proficiency tests of the laboratory by NIST. A description

28
of the proficiency test is given in Appendix A. The total

uncertainty of the dose delivered to an irradiated dosimeter shall

be less than or equal to 5 percent. To meet this criterion, it may

be necessary to use position-specific correction factors when

several dosimeters are irradiated simultaneously.

7. IRRADIATION CONDITIONS

7.1 Orientation

The dosimeters shall be attached to one of the two larger surfaces

of the phantom, at least 5 cm from any edge of the surface, and that

surface shall face the radiation source. The central axis of the

collimated beam shall be perpendicular to that surface, and shall

pass through its geometric center. The position and orientation of

the phantom shall be reproducible and verifiable.

7.2 Distance

The distance between the radiation source and the phantom surface to

which the dosimeters are attached shall be one meter or more. The

distance shall be reproducible and verifiable.

8. VERIFICATION OF TOTAL EXPOSURE (AIR KERMA)

A method shall be used to verify the total exposure (air kerma)

independent of the timer and known exposure (air kerma) rate.

9. CALIBRATION REPORT

The laboratory shall report to the customer the total exposure (air

kerma) for each dosimeter irradiated. For conversion to deep dose or

dose equivalent, the value of the exposure shall be multiplied by 1.03

for i37Cs.

29
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART C.2 - X-RAY IRRADIATION OF PERSONNEL DOSIMETERS

1. INTRODUCTION

The criteria contained in this part of the document apply to the

irradiation of dosimeters at radiation protection levels using x-ray beam

sources. These criteria are supplementary to the general criteria

contained in Part A, and shall be followed if this specific irradiation

service is offered and its inclusion in the Scope of Accreditation is

desired. In that case, both the general criteria and these specific

criteria shall be followed.

2. SCOPE

These criteria apply to the irradiation of dosimeters used for personnel

monitori ng.

3. SOURCE OF X-RAY IRRADIATION

At least one constant potential x-ray generator shall be available to

cover a range of exposures (air kerma) for protection-level irradiations.

The range covered will be a function of the mission and requirements of

the laboratory but a minimal range is 30 mR to BOO R (0.3 mGy to 4 Gy)

.

The laboratory shall be able to perform irradiations using three or more

of the filtered beams described in ANSI N13.ll and DOE/EH-0027 by NIST

beam codes.

4. CONTROL OF RADIATION BEAM

4.1 Shielding

Leakage radiation through a closed shutter or x-ray tubehead

shielding shall be less than 0.1 percent of the open-shutter rates

at the position of the dosimeters.

4.2 Beam Size and Uniformity

The x-ray beams shall be collimated and their size should be limited

to an area consistent with the irradiation requirements. All

dosimeters shall be irradiated with phantom backing, and the beam

size shall be sufficient to irradiate the entire phantom surface

that is facing the tube head. If several dosimeters are being

irradiated simultaneously, the beam size and beam uniformity shall

be sufficiently uniform and characterized to satisfy the requirements of section 6.4.

4.3 Exposure Control

If a shutter is used to control the beam the shutter transit time

shall be known.

30
If a shutter is not used radiation produced prior to achieving beam

stability shall be known in all cases and shall be compensated. The

uncertainties associated with stabilization shall be known. Any

associated systematic timing uncertainties shall be documented and

eliminated or compensated.

EQUIPMENT

In addition to one or more x-ray machines and the associated beam control

devices, the laboratory shall have the same minimum equipment as that

required for gamma-ray calibration (see Part B.l, Section 4), plus the

following:

(1) A phantom consisting of a slab of polymethylmethacrylate with a minimum cross section of 30 x 30 cm and a thickness of 15 cm. The

support system for the phantom shall be rigid and produce minimum

scattered radiation at the dosimeter position(s).

(2) Secondary standard ionization chambers appropriate to the energy and

intensity of x rays for which irradiation services are offered.

CHARACTERIZATION OF THE RADIATION FIELD

6.1 Exposure Rate (Air Kerma Rate)

The radiation field shall be characterized in terms of exposure (air

kerma) rate in the absence of a phantom at the location where the

center of the front surface of the phantom is placed for

i rradiation.

6.2 Scatter

The contribution from room-scattered radiation shall be determined

with the phantom removed from the beam and shall not exceed

5 percent of the exposure (air kerma) rate at any location where a dosimeter is placed for irradiation. The approximate energy

spectrum of room-scattered radiation should be known.

6.3 Radiation Quality

The first half-value layer and homogeneity coefficients for a given

x-ray beam shall be within 5 and 7 percent, respectively, of the

values shown in table 1. If necessary the indicated tube voltage or

added filter, or both, may be adjusted to achieve those values. If

a transmission chamber is used for routine beam monitoring, it shall

be considered to be added filter material.

The intensity of the x-ray beam shall not vary more than 5 percent

across the useful area of the beam.

31
The radiation quality shall be checked for stability at least

annually. Whenever any part that could affect the beam quality is

repaired or replaced the above requirements for radiation quality

shall be met.

6.4 Accuracy

The exposure (air kerma) rate specified by the laboratory as its

reference value shall be within 3 percent of the actual value

defined by comparison with the national standard. This level of

agreement with the national standard shall be periodically verified

through proficiency tests of the laboratory by NIST. A description

of the proficiency test is given in Appendix A. The total

uncertainty of the dose delivered to an irradiated dosimeter shall

be less than or equal to 5 percent. To meet this criterion, it may

be necessary to use position-specific correction factors when

several dosimeters are irradiated simultaneously.

7. IRRADIATION CONDITIONS

7.1 Orientation

The dosimeters shall be attached to one of the two larger surfaces

of the phantom, at least 5 cm from any edge of the surface, and that

surface shall face the radiation source. The central axis of the

collimated beam shall be perpendicular to the surface, and shall

pass through its geometric center. The position and orientation of

the phantom shall be reproducible and verifiable.

7.2 Distance

The distance between the radiation source and the phantom surface to

which the dosimeters are attached shall be one meter or more. The

distance shall be, reproducible and verifiable.

8. VERIFICATION OF TOTAL EXPOSURE (AIR KERMA)

A method shall be used to verify the total exposure (air kerma)

independent of the timer and known exposure (air kerma) rate.

9. CALIBRATION REPORT

The laboratory shall report to the customer the total exposure (air

kerma) for each dosimeter irradiated. For conversion to dose or dose

equivalent, the value of the exposure should be multiplied by the factors

given in ANSI N13.ll or DOE/EH-0027. The reference(s) for the factor(s)

used shall also be given.

32
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART C.3 - NEUTRON IRRADIATION OF PERSONNEL DOSIMETERS

1. INTRODUCTION

The criteria contained in this part of the document apply to irradiation

of dosimeters at radiation protection levels using neutron sources.

These criteria are supplementary to the general criteria contained in

Part A and shall be followed if this specific irradiation service is

offered and its inclusion in the Scope of Accreditation is desired. In

that case, both the general criteria and these specific criteria shall be

fol lowed.

2. SCOPE

These criteria apply to irradiation of dosimeters used for personnel

monitoring. They do not apply to dosimeters that use neutron activation

foils to determine accident level doses.

3. SOURCE OF NEUTRON RADIATION

These criteria apply to neutrons from radionuclide sources, including

sources in a moderator. They do not apply to accelerator produced

neutrons or neutrons from reactors. Neutron sources specified by

ANSI N13.ll or DOE/EH-0027 shall be available. Additional sources may be

used if their spectral distributions, neutron emission rates, and dose

equivalent conversion factors are well documented. The range of dose

equivalents covered will be a function of the mission and requirements of

the laboratory, but 150 mrem to 5 rem (1.5 to 50 mSv) will suffice for

most radiation protection purposes. All irradiations shall refer to

free-field quantities and shall be performed with phantom backing.

4. CONTROL OF RADIATION FIELD

4.1 Shielding

The source storage container shall provide sufficient shielding such

that leakage radiation does not interfere with other uses of the

radiation room by raising the background level. Background

radiation and leakage radiation from all sources in the radiation

room shall not contribute more than 0.1 percent of the total dose

equivalent to which dosimeters are irradiated.

4.2 Irradiation Control

A source transport system shall be provided to transport the source

from the storage container to the irradiation position. Both the

transit time from storage to irradiation position and the associated

dose equivalent contribution to dosimeter irradiation shall be

known.

33
It shall be possible to operate the source transport system with a timer. Any associated random timing uncertainties due to the

transit time of the source shall be known. Any associated

systematic timing uncertainties shall be measured and eliminated or

compensated.

5. EQUIPMENT

In addition to one or more radiation sources and the associated source

transport system, the laboratory shall have at least the following

operable equipment available for calibration or irradiation use:

A phantom consisting of a slab of polymethylmethacrylate with a cross

section of 40 x 40 cm and a thickness of 15 cm. The support system for

the phantom shall be rigid and produce minimum scattered radiation at the

dosimeter position(s). The system should provide for reproducible and

accurate positioning of the phantom with respect to the radiation

source.

6. CHARACTERIZATION OF THE RADIATION FIELD

6.1 Dose Equivalent Rates

The neutron radiation fields used for irradiation shall be

characterized in terms of the free-field dose equivalent rate at the

center of the front surface of the phantom. The neutron emission

rate for each source shall be determined by the NIST. Procedures

for determining the dose equivalent for dosimeters exposed to a 252 Cf source should follow Eisenhauer, Hunt, and Schwartz,

"Calibration Techniques for Neutron Personnel Dosimetry," Radiat.

Prot. Dosim. 10, 43 (1985). Procedures for other sources shall be

documented. Th"e contribution to the dose equivalent due to photon

emission from the neutron source shall be measured and documented.

There shall be verification of the expected dose-equivalent rate

during irradiation.

6.2 Scatter

The contribution of air scattering, room return and source

scattering shall be determined for all irradiation geometries and

distances so that free-field dose equivalents can be determined. To

minimize room scatter, the irradiation room should be as large as is

practically possible and irradiations should be conducted near the

center of the room.

6.3 Accuracy

The dose equivalent rate specified by the laboratory as its

reference value shall be within 5 percent of the actual value

defined by comparison with the national standard. This level of

agreement with the national standard shall be periodically verified

through proficiency tests of the laboratory by NIST. A description

of the proficiency test is given in Appendix A. The total

uncertainty in the assigned neutron dose equivalent for irradiated

34
dosimeters shall be less than or equal to 5 percent, excluding

uncertainties in the dose equivalent conversion factors and the

photon component of the neutron irradiations. To meet this

criterion, it may be necessary to use position-specific correction

factors when several dosimeters are irradiated simultaneously.

7. IRRADIATION CONDITIONS

7.1 Orientation

The dosimeters shall be attached to one of the two larger surfaces

of the phantom, at least 10 cm from any edge of the surface, and

that surface shall face the radiation source. That surface shall be

perpendicular to a radial line from the source center to the phantom

center. The position and orientation of the phantom shall be

reproducible and verifiable.

7.2 Distance

The distance between the center of the radiation source and the

center of the phantom surface to which the dosimeters are attached

shall be at least 50 cm. The dose equivalent shall be calculated at

the location of each dosimeter. It shall be reproducible and

veri f iable.

8. VERIFICATION OF DELIVERED DOSE EQUIVALENT

A method shall be used to verify the delivered dose equivalent independent of the timer and known dose equivalent rate. Possible verification

methods include an off-axis detector or a passive detector exposed with

each irradiation.

9. CALIBRATION REPORT

The laboratory shall report to the customer the free-field dose equivalent for each dosimeter irradiated. The ratio of the dose equivalent

arising from photon emission by the radiation source to the neutron dose

equivalent should be reported.

35
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART C.4 - BETA-PARTICLE IRRADIATION OF PERSONNEL DOSIMETERS

1. INTRODUCTION

The criteria contained in this part of the document apply to irradiation

of dosimeters at radiation protection levels using beta-particle sources.

These criteria are supplementary to the general criteria contained in

Part A, and shall be followed if this specific irradiation service is

offered and its inclusion in the Scope of Accreditation is desired. In

that case, both the general criteria and these specific criteria shall be

fol 1 owed.

2. SCOPE

These criteria apply to irradiation of dosimeters used for personnel

moni tori ng.

3. SOURCES OF BETA RADIATION

One or more sources of beta radiation shall be available for irradiation

services. They may take the form of point sources or slab sources. The

sources should meet the requirements of national or international

standards (i.e., ANSI N13.ll; DOE/EH-0027, ISO 6980). The dose range

covered will be a function of the mission and requirements of the

laboratory, but 150 mrad to 10 rad (1.5 to 100 mGy) should be sufficient

for most radiation protection purposes.

4. EQUIPMENT

In addition to one or more radiation sources and the associated beam

control devices, the laboratory shall have the same minimum equipment as

that required for gamma-ray calibration (see Part B.l, Section 4), with

the exception of secondary standard ionization chambers. They shall be

replaced by an extrapolation chamber or thin-window fixed volume

ionization chamber that covers the energy and intensity ranges used for

irradiation services. The laboratory shall also have a phantom

consisting of a slab of polymethylmethacrylate with a minimum cross

section of 30 x 30 cm and a minimum thickness of 5 cm. The support

system for the phantom shall be rigid and produce minimum scattered

radiation at the dosimeter position(s).

5. POINT SOURCES

5.1 Control of Radiation Beam

5.1.1 Shielding

The source storage containers shall provide sufficient

shielding such that leakage radiation does not interfere with

other uses of the radiation room by raising the background

36
level. Background and leakage radiation from all sources of

radiation within the room shall not contribute more than

0.1 percent of the total dose to which dosimeters are

i rradiated.

5.1.2 Beam Size and Uniformity

The beam size shall be sufficient to irradiate the entire

phantom surface that is facing the source. If several

dosimeters are irradiated simultaneously the beam shall be

sufficiently uniform and characterized to satisfy the

requirements of section 5.2.2. The use of an appropriate

flattening filter may be required to achieve this.

5.1.3 Beam Emission Control

The irradiator shall have a built-in device to control

emission of the beta radiation. It shall be possible to

operate the emission control device with a timer. Any

associated random timing uncertainties due to transit time of

the device shall be known. Any associated systematic timing

uncertainties shall be measured and eliminated or

compensated.

5.2 Characterization of Radiation Field

5.2.1 Dose Rate

The beta radiation field used for irradiation shall be

characterized in terms of dose rate at a depth of 7 mg/cm 2 in

ti ssue.

5.2.2 Accuracy

The dose rate specified by the laboratory as its reference

value shall be within 3 percent of the actual value defined

by comparison with the national standard. This level of

agreement with the national standard shall be periodically

verified through proficiency tests of the laboratory by NIST.

A description of the proficiency test is given in Appendix A.

The total uncertainty of the dose delivered to an irradiated

dosimeter shall be less than or equal to 5 percent. To meet

this criterion, the use of a flattening filter and/or

position-specific correction factors may be required when

several dosimeters are irradiated simultaneously.

5.3 Source Containment

Source containment must be sufficiently sturdy to permit its safe

and routine use. At the same time, it shall be sufficiently thin to

ensure the beta particle energy spectrum of sources specified in

ISO 6980.

37
5.4 Irradiation Conditions

5.4.1 Orientation

The dosimeters shall be attached to one of the two larger

surfaces of the phantom, at least 5 cm from any edge of the

surface, and that surface shall face the radiation source.

The central axis of the collimated beam shall be

perpendicular to that surface, and shall pass through its

geometric center. The position and orientation of the

phantom shall be reproducible and verifiable.

5.4.2 Distance

The distance between the radiation source and the phantom

surface to which the dosimeters are attached shall comply

with requirements in ANSI N13.ll or DOE/EH-0027. It shall be

reproducible and verifiable.

SLAB SOURCES

Slab sources may be used when such irradiation geometry is more

appropriate than a point source irradiation geometry.

6.1 Slab Size

The dimensions of the source shall exceed the dimensions of the

irradiated dosimeter including all radiation sensitive elements.

6.2 Source Characteristics

6.2.1 The slab shall have a protective covering in the range of

3 to 7 mg/cm 2 inclusive. For uranium, the dose rate at

100 mg/cm 2 divided by the dose rate at 7 mg/cm 2 shall be

0.58 ± 0.04. The in-phantom dose rate at 1000 mg/cm 2 shall

be less than 3 percent of the dose rate at 7 mg/cm 2

. Appropriate dosimeters shall be used to confirm these

relative dose rates.

6.3 Oose Rate

The beta radiation field on or near (< 1 cm) the surface of the

source shall be characterized in terms of absorbed dose rate in

tissue at a depth of 7 mg/cm 2 . An extrapolation ionization chamber

or a thin fixed volume ionization chamber shall be used to determine

the dose rate.

6.4 Accuracy

The dose rate specified by the laboratory as its reference value

shall be within 3 percent of the actual value defined by comparison

with the national standard. This level of agreement with the

national standard shall be periodically verified through proficiency

38
tests of the laboratory by NIST. A description of the proficiency

test is given in Appendix A* The total uncertainty of the dose

delivered to an irradiated dosimeter shall be less than or equal to

5 percent.

6.5 Orientation

Dosimeters shall lie flat on the source surface or be suspended

parallel to the surface with a maximum source-to-dosimeter distance

of 0.5 cm.

7. VERIFICATION OF DELIVERED DOSE

For point sources, a method shall be used to verify the delivered dose

independent of the timer and known dose rate. Possible verification

methods include an off-axis detector, a small detector embedded in a corner of the phantom or a passive detector exposed with each

i rradi ati on.

8. CALIBRATION REPORT

The laboratory shall report to the customer the total dose at 7 mg/cm 2

depth for each dosimeter irradiated.

39

CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART D - GAMMA-RAY SOURCE CALIBRATION FOR EXPOSURE (AIR KERMA) RATE

1. INTRODUCTION

The criteria contained in this part apply to the calibration of gamma-ray

sources in terms of exposure (air kerma) rate in free air. These

criteria are supplemental to the general criteria contained in Part A of

this document, and are to be followed if this specific calibration

service is offered and its inclusion in the Scope of Accreditation is

desired. In that case, both the general and these specific criteria

shall be met.

2. TYPES OF SOURCES CALIBRATED

These criteria are to allow sealed sources in transportable containers,

which can be shipped easily, to be calibrated and shipped back to the

user. The ranqe of exposure (air kerma) rates shall be from 2 mR/h to

50 R/h (20 uGy/h to 0.4 Gy/h) measured at the 1 m point in free air. The

following sources shall be allowed for this type of calibration: 21+ iAm,

I37cs, or 60Co.

3. EQUIPMENT

The laboratory shall have at least the equipment specified in Part B.l,

Section 4, as well as the following equipment dedicated to calibration

use:

A source of gamma radiation greater than or equal to the activity of

the radiation source to be calibrated. It shall have been

calibrated in terms of exposure (air kerma) rate as a function of

distance, and be subject to periodic quality assurance on at least

an annual basis. Accreditation under Part B.l precludes this

requi rement

4. CONDITIONS OF CALIBRATION

4.1 Method

The calibration shall be performed by measurement of the source

output using secondary standard ionization chambers or working

standard ionization chambers that were calibrated against the

secondary standards. The energy dependence of the standard

chamber(s) shall be known over the range of photon energies to be

measured.

41
4.2 Geometry

The source-detector geometry shall be carefully defined. Scattering

(excluding that from the source and collimator) from the

surroundings should be minimal and shall not exceed 10 percent of

the exposure (air kerma) rate at any location where a detector is

placed for source calibration. The approximate energy spectrum of

scattered radiation should be known.

4.3 Attenuation

If an attenuator is used by the laboratory to deliberately reduce

the exposure (air kerma) rate produced by the source, the effect of

the attenuator on the energy spectrum of the gamma radiation should

be known and the actual attenuation factor shall be determined by

the laboratory. The effect of any electron fluence at the

calibration position shall be considered.

5. SPECIFICATION OF SOURCE OUTPUT

5.1 Accuracy

The laboratory shall state the estimated uncertainty of the measured

output of the source being calibrated, and this shall not exceed

5 percent total. This total uncertainty shall be calculated on the

basis of a thorough analysis of possible errors. Accuracy shall be

maintained through periodic i ntercompari son with a national

standard.

5.2 Calibration Report

The calibration report shall include the following information for

each source calibration:

(a) a complete description of the source-detector geometry used;

(b) the measured exposure (air kerma) rate at the distance(s) of

calibration, with and without specified attenuators;

(c) a description of attenuator(s) used;

(d) the estimated uncertainty in the reported exposure (air kerma)

rate.

42
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART E - X-RAY CALIBRATION OF INSTRUMENTS FOR DIAGNOSTIC LEVELS

INTRODUCTION

The criteria contained in this part of the document apply to calibration

of instruments at diagnostic radiology levels using an x-ray source.

These criteria are supplementary to the general criteria and shall be

followed if this specific calibration service is offered and its

inclusion in the laboratory's Scope of Accreditation is desired. Both

the general criteria and these specific criteria shall be followed in

that case.

SOURCE OF X-RAYS

The laboratory shall have a constant potential x-ray machine available

for calibration of instruments. It should operate at potentials from 30

to 150 kV as a minimum range. The radiation field produced shall cover,

as a minimum range, exposure (air kerma) rates from 20 to 100 R/h (180 to

900 nGy/h) , with a stability sufficient to calibrate instruments

according to documented laboratory procedures. During calibration of an

instrument, the exposure (air kerma) rate shall not vary by more than

± 1 percent.

CONTROL OF RADIATION BEAM

3.1 Beam Colli mat ion

The x-ray beam emitted from the tube housing shall be collimated

so that its size is limited to the minimum area consistent with

calibration requirements. Provision shall be made for identifying

the central axis, and the boundaries of the useful area of the

beam shall be known.

3.2 Shutter

A shutter shall be used to control emission of the x-ray beam from

the tube housing. If the beam is used for calibration of

exposure-measuring instruments, the shutter transit time shall be

known.

3.3 Exposure Control

If the x-ray beam is used for calibration of exposure (air kerma)

measuring instruments, the shutter shall be operated by a timer or

a suitable charge integrating device. Any associated errors due

to shutter transit times shall be documented and eliminated or

compensated.

43
EQUIPMENT

In addition to one or more x-ray machines and associated control devices,

the laboratory shall have the same minimum equipment as that required for

gamma ray calibration (see Part B.l, Section 4) with the following

exception - the secondary standard ionization chambers shall be

appropriate to the energy and intensity of x rays for which calibration

services are offered.

Additionally, the laboratory shall be equipped with filters to permit the

production of a variety of x-ray beam qualities (see paragraph 5.4,

below)

.

CHARACTERIZATION OF THE RADIATION FIELD

5.1 Exposure Rate (Air Kerma Rate)

The x-ray field used for calibration shall be characterized in terms

of exposure (air kerma) rate at the location where the effective

center of the instrument's detector is placed for calibrations.

5.2 Scatter

The effect of room-scattered radiation (relative to a radiation

field with minimal room scatter) on the accuracy of calibration of

each instrument type shall be known at each location where a detector is placed for instrument calibration.

5.3 Accuracy

The exposure (air kerma) rate specified by the laboratory as its

reference value shall be within ± 5 percent of the actual value

defined by comparison with the national standard. This level of

agreement with the national standard shall be demonstrated through

periodic proficiency tests of the laboratory by the National

Institute of Standards and Technology (NIST). A description of the

proficiency test is given in Appendix A.

5.4 Radiation Quality

The x-ray beam emitted from the tube housing shall be filtered

before use for calibration purposes. The laboratory shall provide

calibration services using at least five of the following radiation

qual ities:

44
Beam First Half-Value Layer Homogeneity Coefficient Added Filter^ 1 )

Code Al Cu Al Cu Al Cu

(mm) (mm) (mm) (mm)

M30 0.36 64 0.50

M50 1.02 0.032 66 62 1.021

L80 1.83 58 1.284

LI 00 2.8 59 1.978

Ml 00 5.0 0.20 72 55 5.0

M150 10.2 0.67 87 62 5.0 0.25

(Djhe added filter thi cknesses relate specifically to the NIST beams, and

provided for guidance only.

For either aluminum or copper, the first half-value layer and

homogeneity coefficients for a given x-ray beam shall be within

5 percent and 7 percent, respectively, of the values shown in the

above table. If necessary the indicated tube voltage or added

filter, or both, may be adjusted to achieve those values. If a transmission chamber is used for routine beam monitoring, it shall

be considered to be added filter material.

The intensity of the x-ray beam shall not vary more than 5 percent

across the useful area of the beam.

The radiation quality shall be checked for stability at least

annually. Whenever any part that could affect the beam quality is

repaired or replaced the above requirements for radiation quality

shall be met.

6. CALIBRATION REPORT

An instrument calibration report shall include, as a minimum, the x-ray

beam used for calibration, the reference exposure (air kerma) rate or

rates at which the instrument was calibrated, the exposure (air kerma)

rate indicated by the instrument, and the correction factor at each

calibration point. In the case of integrating instruments, in addition

to the x-ray beam and exposure (air kerma) rate, the reference exposure

(air kerma), instrument reading, and correction factor shall be included.

One calibration point and a linearity check should be included for each

range of the instrument, where possible. The orientation of the

instrument with respect to the radiation beam shall be described or

illustrated in the calibration report. For instruments that use a vented

ionization chamber, the reported values shall be referenced to a temperature of 22 °C and a barometric pressure of 760 mm Hg, and the

equation needed to convert to other temperatures and pressures shall be

provided.

45

CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART F - CALIBRATION OF REFERENCE-CLASS INSTRUMENTS

PART F.l - GAMMA-RAY CALIBRATION OF REFERENCE-CLASS INSTRUMENTS

1. INTRODUCTION

The criteria contained in this part apply to the calibration of

reference-class instruments at radiation protection levels usiny one or

more gamma-ray sources. The reference-class instruments calibrated

according to these criteria are intended for use by a customer and are

not intended for use as working standards in the laboratory performing

the calibration. These criteria are supplementary to the general

criteria contained in Part A. Both the general criteria and these

specific criteria shall be followed if inclusion of this calibration

service in the Scope of Accreditation is desired.

2. SOURCES OF GAMMA RADIATION

One or more of the following radiation sources shall be available for use

in the calibration of reference-class instruments:

The radiation fields produced by the sources should cover a range of

exposure (air kerma) rates suitable for protection-level calibration.

3. RADIATION CONTROL

3.1 Shielding

Radiation barriers and/or storage containers for sources shall

provide sufficient shielding so that background radiation in the

calibration area is sufficiently low as to not interfere with

ongoing calibration work.

3.2 Beam Collimation

The gamma radiation beam emitted from a source that is used for

calibration shall be collimated so that its size is limited to an

area consistent with calibration requirements. An exception to this

requirement is a calibration facility sufficiently large to provide

a low room-scatter radiation environment for instrument calibration,

e.g., an uncollimated source in a low scatter room.

Radionuclide Nominal Energy

i37Cs

6 0Co

660 keV

1.25 MeV

47
3.3 Source Exposure

The source storage container shall have a mechanism to control

exposure in the gamma beam. If the radiation source is used for

calibration of exposure (air kerma) measuring (as contrasted with

exposure-rate (air kerma-rate) measuring) instruments, the shutter

or source transit time and its effect on the total radiation

exposure (air kerma) shall be known.

3.4 Exposure Control

If the radiation source is used for the calibration of exposure (air

kerma) measuring instruments (see 3.3, above), the shutter or source

transfer shall be initiated and terminated by a timer or the

exposure (air kerma) shall be controlled by use of a transmission

chamber. Any associated systematic timing uncertainties shall be

documented and eliminated or compensated.

4. EQUIPMENT

In addition to one or more radiation sources and associated control

devices, the laboratory shall have the same minimum equipment as that

required for gamma-ray calibration (see Part B.l, Section 4).

5. CHARACTERIZATION OF THE RADIATION FIELD

5.1 Exposure Rate (Air Kerma Rate)

The gamma radiation field used for calibration shall be characterized in terms of exposure (air kerma) rate at a given position or

distance from the source. The exposure (air kerma) rate shall be

known at each distance used.

5.2 Scattered Radiation

The effect of room-scattered radiation (relative to a radiation

field with minimal room scatter) on the accuracy of calibration of

each instrument type shall be known at each location where a detector is placed for instrument calibration.

5.3 Attenuation

If an attenuator is used to reduce the exposure (air kerma) rate at

any location in the radiation field, the effect of the altered

radiation spectrum (relative to an unattenuated radiation spectrum)

on the accuracy of calibration of each instrument type shall be

known. The effect of any electron fluence at the calibration

position shall be considered. The approximate energy spectrum of

the attenuated radiation field should be known.

48
6. ACCURACY OF CALIBRATION

The chamber or instrument calibration factor specified by the laboratory

for each source of radiation shall be within 3 percent of the true value

as defined by comparison with a national standard. This level of

agreement with the standard shall be demonstrated through periodic

proficiency testing by NIST. A description of the proficiency test is

given in Appendix A.

7. CALIBRATION REPORT

An ionization-chamber calibration report shall include, as a minimum, the

radionuclide or photon energy used, the reference exposure (air kerma)

rate or rates at which the chamber was calibrated, and the calibration

factor of the chamber at each calibration point in terms of exposure (air

kerma) per unit charge. Orientation of the chamber with respect to the

radiation beam shall be described, the polarity and magnitude of the

polarizing potential shall be stated, and the use of a build-up cap shall

be noted.

An instrument calibration report shall include, as a minimum, the

radionuclide or photon energy used, the reference exposure (air kerma)

rate or rates at which the instrument was calibrated, the exposure (air

kerma) rate indicated by the instrument, and the correction factor at

each calibration point. In the case of integrating instruments, in

addition to the radionuclide and exposure (air kerma) rate, the reference

exposure (air kerma), instrument reading, and correction factor shall be

included. One calibration point and a linearity check should be included

for each range of the instrument, where applicable. The orientation of

the instrument with respect to the radiation beam shall be described or

illustrated in the calibration report, and the use of a build-up cap

shall be noted.

For a vented ionization chamber or an instrument that uses such a chamber, the reported values shall be referenced to a temperature of

22 °C and a barometric pressure of 760 mm Hg, and the equation needed to

convert to other temperatures and pressures shall be provided.

49
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

PART F.2 - X-RAY CALIBRATION OF REFERENCE-CLASS INSTRUMENTS

1. INTRODUCTION

The criteria contained in this part apply to the calibration of

reference-class instruments at radiation protection or diagnostic levels

using an x-ray source. The reference-class instruments calibrated

according to these criteria are intended for use by a customer and are

not intended for use as working standards in the laboratory performing

the calibration. These criteria are supplementary to the general

criteria contained in Part A. Both the general criteria and these

specific criteria shall be followed if inclusion of this calibration

service in the Scope of Accreditation is desired.

2. SOURCE OF X RAYS

A constant potential x-ray generator shall be available for use in the

calibration of reference-class instruments. Its maximum ripple shall not

exceed 2 percent and it should be operable over a minimum range of 30 to

150 kV, 1 to 10 mA.

The radiation fields produced by the x-ray generator shall cover a range

of exposure (air kerma) rates suitable for protection-level and

diagnostic calibration. During calibration of an instrument, the

exposure (air kerma) rate shall not vary by more than 1 percent from the

nominal rate.

3. CONTROL OF THE RADIATION BEAM

3.1 Radiation Production

The production of a useful beam of radiation may be by means of the

application of high voltage to the x-ray tube or the opening of a mechanical shutter (which normally acts as a shield to the x-ray

beam)

.

3.2 Beam Collimation

The x-ray beam emitted from the tube housing shall be collimated so

that its size is limited to an area consistent with calibration

requirements. Provision shall be made for identifying the central

axis, and the boundaries of the useful area of the beam shall be

known.

3.3 Exposure Control

If the radiation source is used for the calibration of exposure (air

kerma) measuring instruments, the radiation beam shall be controlled

by a timer or the exposure (air kerma) shall be controlled by use of

50
a transmission chamber. The timing error due to the shutter transit

times or high voltage ramping shall be documented and eliminated or

compensated.

EQUIPMENT

In addition to one or more x-ray machines and associated control devices,

the laboratory shall have the same minimum equipment as that required for

gamma ray calibration (see Part B.l, Section 4) with the following

exception - the secondary standard ionization chambers shall be

appropriate to the energy and intensity of x rays for which calibration

services are offered.

Additionally, the laboratory shall be equipped with filters to permit the

production of a variety of x-ray beam qualities (see paragraph 5.3,

below)

CHARACTERIZATION OF THE RADIATION FIELD

5.1 Exposure Rate (Air Kerma Rate)

The x-ray radiation field used for calibration shall be

characterized in terms of exposure (air kerma) rate at a given

position or distance from the anode of the x-ray tube. The exposure

(air kerma) rate shall be known at each distance used.

5.2 Scattered Radiation

The effect of room-scattered radiation (relative to a radiation

field with minimal room scatter) on the accuracy of calibration of

each instrument type shall be known at each location where a detector is placed for instrument calibration.

5.3 Radiation Quality

The x-ray beam emitted from the tube housing shall be filtered

before use to provide the appropriate radiation quality for calibration purposes. If a transmission chamber is used for routine beam

monitoring, it shall be considered to be added filter material.

Three or more of the beams shown in table 1 (in Part B.2) shall be

avai 1 able.

The first half-value layer and homogeneity coefficients for a given

x-ray beam shall be within 5 and 7 percent, respectively, of the

values shown in table 1. If necessary the indicated tube voltage or

added filter, or both, may be adjusted to achieve those values.

The intensity of the x-ray beam shall not vary more than 5 percent

across the useful area of the beam.

The radiation quality shall be checked for stability at least

annually. Whenever any part that could affect the beam quality is

repaired or replaced the above requirements for radiation quality

shall be met.

51
6. ACCURACY OF CALIBRATION

The chamber or instrument calibration factor specified by the laboratory

for each x-ray beam shall be within 3 percent of the true value as defined by comparison with a national standard. This level of agreement

with the standard shall be demonstrated through periodic proficiency

testing by NIST. A description of the proficiency test is given in

Appendix A.

7. CALIBRATION REPORT

An i oni zati on-chamber calibration report shall include, as a minimum, a description of beam quality in terms of the codes in table 1 or an

equivalent method, the reference exposure (air kerma) rate or rates at

which the chamber was calibrated, and the calibration factor of the

chamber at each calibration point in terms of exposure (air kerma) per

unit charge. Orientation of the chamber with respect to the radiation

beam shall be described, and the polarity and magnitude of the polarizing

potential shall be stated.

An instrument calibration report shall include, as a minimum, the x-ray

beam used for calibration, the reference exposure (air kerma) rate or

rates at which the instrument was calibrated, the exposure (air kerma)

rate indicated by the instrument, and the correction factor at each

calibration point. In the case of integrating instruments, in addition

to the x-ray beam and exposure (air kerma) rate, the reference exposure

(air kerma), instrument reading, and correction factor shall be included.

One calibration point and a linearity check should be included for each

range of the instrument, where possible. The orientation of the

instrument with respect to the radiation beam shall be described or

illustrated in the calibration report.

For a vented ionization chamber or an instrument that uses such a chamber, the reported values shall be referenced to a temperature of

22 °C and a barometric pressure rf 760 mm Hg, and the equation needed to

convert to other temperatures and pressures shall be provided.

52
CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

APPENDIX A - NIST PROFICIENCY TESTS

Section 6.3 of the General Criteria (Part A) requires that a laboratory's

proficiency be tested annually by the National Institute of Standards and

Technology (NIST). Each proficiency test shall be representative of one or

more types of calibration for which the laboratory is accredited. This

appendix provides descriptive information about those required tests.

Table Al identifies an appropriate proficiency test for each radiation

quantity addressed in the various specific criteria contained in Parts B

through F. If the quantity of interest, for example, is gamma exposure (air

kerma) rate, an appropriate method for conducting the test is that NIST will

calibrate an ionization chamber using an identified photon source, that same

chamber will be sent to the participating laboratory for its calibration, and

the calibration factor obtained by the latter will be compared with that

obtained by NIST. If the difference between the two results is within the

limit set forth in the specific criteria (usually in the "accuracy" section),

performance of the laboratory is considered to be satisfactory.

For a laboratory that is accredited under the criteria of Part C.l for

irradiation of dosimeters, the proficiency test method may involve irradiation

of test dosimeters by the participating laboratory, for subsequent readout by

NIST to determine whether the delivered dose was within prescribed limits, or

it may involve an ionization chamber as described above.

The proficiency test method for x-ray exposure (air kerma) rate is similar to

that for gamma exposure (air kerma) rate. For beta dose rate, NIST could

calibrate either an appropriate source or instrument, send it to the

participating laboratory for its calibration, and compare calibration results.

For neutron fluence rate or dose equivalent rate an appropriate method

involves calibration of a remmeter, and alpha emission rate may involve

calibration of a suitable source.

One annual proficiency test may satisfy that requirement simultaneously for

several specific criteria. If a laboratory is accredited, for example, to use

a 137Cs source for calibration of survey instruments (B.l), irradiation of

personnel dosimeters (C.l), calibration of sources (D), and calibration of

reference-class instruments (F.l), a single annual proficiency test could be

sufficient for simultaneous satisfaction of the requirement for all four of

those services. The most stringent performance level required in any one of

these four specific criteria (3 percent) would, of course, have to be I satisfied by the single proficiency test.

It is not feasible that an annual proficiency test for a particular radiation

quantity should attempt to cover the entire range of exposure (air kerma)

rates, dose rates, fluence rates, or emission rates of interest. Instead,

each annual test will involve only a representative part of the possible

range, with the intent of covering the complete range over a period of years.

53
Similarly, if a laboratory uses many of the x-ray beam codes, the annual

proficiency test will not involve each code, but all codes will be covered in

subsequent years.

There are a few cases where NIST does not have a radiation source similar to

that used by a participating laboratory. In that case NIST may calibrate the

proficiency test instrument with a surrogate source that has comparable

characteristics. As an example, the ionization chamber used to test for gamma

exposure (air kerma) rate may be calibrated by NIST with x rays instead of an

21+iAm source if the participating laboratory wants to be accredited for using

the latter. The energy spectrum of the x-ray beam used by NIST would

approximate that from an 21+1 Am source.

The proficiency tests identified in table Al are considered to be appropriate

for their associated radiation quantities and the relevant criteria. They are

not, however, intended to be an exclusive set. Proficiency tests not

identified in the table may also be appropriate, and may be used when

mutually acceptable to NIST and the participating laboratory.

54
TABLE Al. Appropriate NIST Proficiency Tests for Various Radiation Quantities

Radiation Quantity

(rate)

gamma- ray exposure

or air kerma

x-ray exposure

or air kerma

beta dose

neutron fluence

or dose equivalent

alpha emission

Source

2^iAm

137CS

eoco

NIST codes

20H1

90Sr/90Y

99TC

85|<r

U.'nat

U dep

106Ru /106Rh b.3

Relevant

Cri teri a B.l

D

B. l

C. l

D

F.l

B.l

D

F.l

B. 2

C. 2

E

F.2

B.3

B. 3

C. 4

B. 3

C. 4

B.3

B.3

B. 3

C. 4

B. 3

C. 4

238p u (Be)

239p u (Be)

2«»iAm(Be)

252Cf

2 52cfmod

unat

u dep

238p u 239Pu

Tn nat

230Jh

B.4

B.4

B.4

B. 4

C. 3

B. 4

C. 3

B.5

B.5

B.5

B.5

B.5

B.5

Appropri ate

NIST Proficiency Test

ion chamber calibrated wi

ion chamber calibrated wi

ion chamber calibrated wi

dosimeter or ion chamber

with i37Cs

on chamber calibrated wi on chamber calibrated wi

on chamber calibrated wi on chamber calibrated wi

on chamber calibrated wi

th x-rays

th x-rays

th i37Cs

cal i brated

th

th

th

th

th

137QS

137CS

soco

eoco

6 0CO

ion chamber calibrated with

appropriate beams

dosimeter or ion chamber calibrated

with appropriate beams

ion chamber calibrated with

appropriate beams

ion chamber calibrated with

appropriate beams

calibrated ll* 7 pm source

calibrated 20471 source

calibrated 20471 source

calibrated 90s r/90Y source

dosimeter or calibrated 90sr/90y

source

cal i brated

cal i brated

cal i brated

cal i brated

cal i brated

cal i brated

cal i brated

99Tc

85Kr

U.

u

'nat

nat

dep

source

source

source

source

source

source dep

i06RU /i06Rh source

remmeter calibrated with 24i/\m(Be)

remmeter calibrated with 241Am(Be)

remmeter calibrated with 24i/\m(Be)

remmeter calibrated with 252Cf, bare

remmeter or dosimeter irradiated with

252cf, bare

remmeter calibrated with 252cf,

moderated

remmeter or dosimeter irradiated with

252cf, moderated

cal

cal

brated U nat source

brated U^p source

brated 238pu source

brated 239p u source

cal

cal

cal

calibrated 230jh source

brated Th nat source

55

CRITERIA FOR THE OPERATION

OF FEDERALLY-OWNED SECONDARY CALIBRATION LABORATORIES

APPENDIX B - GLOSSARY OF TERMS

accreditation - recognition of a laboratory's competence to perform

calibrations in accordance with established criteria.

accuracy - the degree of agreement of an observed value (i.e., the value

indicated by a measurement process) with the true value of the quantity

being measured. When expressed in percent it is calculated as

attenuator - absorbing material intentionally placed in the path of a radiation beam to reduce its intensity.

calibration (instrument) - comparison of the response of a given instrument

with the response of a standard instrument when both are exposed to the

same radiation source under the same conditions; or the determination of

the response of the given instrument when exposed to a known radiation

field under well-defined conditions.

calibration (source) - determination of the output of a radiation source by

comparison with the output of a standard source, or by the response of a standard instrument to the output of the source.

collimator - a device used to limit the size, shape, and direction of a radiation beam.

constant potential - a unidirectional voltage of essentially constant

magnitude.

correction factor - the ratio of the reference value of a radiation quantity

criteria - documented minimum performance characteristics that must be

satisfied by a laboratory in order to achieve accreditation.

critical equipment - any piece of equipment that has a unique calibration

(correction) factor and is used by the laboratory to provide a calibration service. Examples are a radiation source, secondary

standard, and an electrometer.

error - for a particular measurement result, the difference between the

measured value x and the true value t (i.e., x

- t)»

extrapolation chamber - an ionization chamber in which the separation of

electrodes is variable, thereby enabling a series of measurements with

decreasing separation so that the measured ion current per unit volume

can be extrapolated to the case of infinitesimal volume.

accuracy = observed value - true value

true value

x 100

57
free-air facility - a calibration facility in which the radiation emitted by

the source reaches the instrument under calibration with minimal scatter

from nearby structures.

free-field quantity - a radiation quantity, such as neutron dose equivalent,

that has been corrected to remove contributions from scattered radiation

(e.g., air scattering and room return).

half-value layer (HVL) - the thickness of a specified substance which, when

introduced into the path of a given beam of radiation, reduces the value

of a specified radiation quantity upon transmission through the substance

by one-half.

homogeneity coefficient - the ratio of the first half-value layer to the

second half-value layer, multiplied by 100.

instrumentation - a generic term that includes radiation sources and

instruments or devices used to measure radiation levels.

ionization chamber - a gas-filled enclosure in which ion pairs created by

incident radiation are collected on electrodes.

leakage radiation - radiation other than the useful beam emitted from an x-ray

tube housing or a source container.

point source - a radiation source whose maximum dimension is small compared

with the source-to-detector distance used for irradiation of a dosimeter

or instrument.

proficiency test - a test of the performance of a laboratory by

intercompari son of the results obtained from calibration of a common

instrument or radiation source by both the laboratory under test and the

laboratory conducting the test.

protocol - the documented policies and procedures used by a laboratory in

conduct of calibration.

quality assurance - the general program of actions taken to ensure a satisfactory level of quality in the services provided by a laboratory.

quality control - the specific, technical procedures followed routinely to

detect and correct any problems that would cause a laboratory to provide

services at an unacceptable level of quality.

reference-class instrument - an instrument or ionization chamber that is

sufficiently precise and accurate to serve as a tertiary standard.

reference value - the value of a particular quantity (e.g., exposure or air

kerma rate) that characterizes a laboratory's radiation field. It is the

value to which the indicated value of an instrument under calibration is

compared.

58
residual maximum beta energy, E

pes

- the maximum energy of the beta spectrum

from all beta decay branches of a radionuclide at the calibration

di stance.

residual maximum beta range, R

pes

- the range in an absorbing material of a beta spectrum of residual maximum energy, E

res

.

ripple - the periodic variation in the potential difference between the

cathode and anode of an x-ray tube, resulting from rectification of an

alternating current. As the ripple is decreased by the use of filtering

circuits, a constant potential is more nearly approached.

scattered radiation - radiation that, as the result of interaction with

matter, has had its direction changed and, for some interactions, its

energy decreased.

room-scattered radiation - radiation that is scattered from the walls,

floor, ceiling, or other structural part of the radiation room.

scope of accreditation - a document issued by an accrediting organization that

specifies the radiation types, energies, and intensities for which a laboratory is accredited to calibrate a particular type of

instrumentation.

shall - when "shall" is used in conjunction with an action or condition

specified in this document, that action or condition is required to be

implemented.

should - when "should" is used in conjunction with an action or condition

specified in this document, that action or condition is not required to

be implemented but is recommended as good practice.

slab source - a radiation source whose maximum dimension is large compared

with the source-to-detector distance used for irradiation of a dosimeter

or instrument.

standard - a physical realization of the unit of a quantity, used as a reference for the calibration of an instrument or a lower-level

standard.

national standard - a standard that serves as the primary reference for a specified quantity in a particular country.

secondary standard - a standard that was calibrated by direct comparison

with a pertinent national standard.

tertiary standard - a standard that was calibrated by direct comparison

with a pertinent secondary standard.

working standard - a standard that is calibrated periodically by direct

comparison with an appropriate secondary standard, and is only used

for routine calibrations of instruments.

59
support equipment - any piece of equipment, including critical equipment, used

by the laboratory to provide a calibration service.

survey instrument - a hand-held instrument used to measure ionizing radiation

for purposes of radiation protection. It does not include instruments

designed as area, portal, or personnel monitors, as monitors of

radioactive gases or airborne particulates, or as dose or beam

calibrators for medical diagnostic or therapeutic applications.

thin source - a radiation source consisting of alpha-emitting radioactive

material uniformly distributed in a thin layer over the surface of a flat

metallic backing plate so as to cause minimal degradation of the alpha

energy spectrum.

transmission chamber - a thin-walled ionization chamber designed to monitor a radiation beam that is transmitted through the chamber with minimal

attenuation or scatter.

uncertainty - the estimated limits of the error in a measurement result.

random uncertainty - that uncertainty associated with error components

that can be and are estimated by a statistical analysis of repeated

measurements, and which indicate the degree of precision.

systematic uncertainty - that uncertainty associated with error

components that are biased, and those which may be due to random

causes but cannot be or are not assessed by statistical methods.

total uncertainty - an estimate of the likely limits of the error in a measurement result, obtained by combining all of the random and

systematic uncertainty components.

60
BIBLIOGRAPHY

American National Standards Institute (ANSI), Criteria for Tes ting Personnel

Dosimetry Performance , ANSI N13. 11-1983, American National Standards

Institute, New York, NY (1983).

Eisenhauer, C. M., Hunt, J., and Schwartz, R. B., Calibration Techniques for

Neutron Personnel Dosimetry, Radiat. Prot. Dosim. _10, 43 (1985).

International Organization for Standardization (ISO), Reference Beta

Radiations for Calibrating Dosemeters and Doseratemeters and for

Determining their Response as a Function of Beta Radiation Energy , ISO 6980-1984, International Organization for Standardization, Geneva

(1984).

International Organization for Standardization (ISO), Neutron Reference

Radiations for Calibrating Neutron-Measuring Devices Used for Radiation

Protection Purposes and for Determining Their Response as a Function of

Neutron Energy , ISO 8529-1989, International Organization for

Standardization, Geneva (1989).

International Organization for Standardization (ISO), Pro cedures for

Calibrating and Determining t he Energy Response of N eutron Measur ing

Devices used for Radiation Protection , ISO/CD 10647, International

Organization for Standardization, Geneva (1991).

Lorenz, A., A Survey of Neutron Sources and The ir Appli cations, UCRL-51298,

TID-4500, UC-34, Lawrence Livermore Laboratory 1T972)

Prevo, C. T., Comparison of Calculated Neutron Spectrum and Dose Equivalent

from NBS and LLNL 15-cm D„0 Spheres, Hazards Control Department Annua l Technology Review , UCRL-50007-83, UC-41, Lawrence Livermore National

Laboratory, 68 (1983)

Schwartz, R. B. and Eisenhauer, C. M., Procedures for Calibrating Neutron

Personnel Dosimeters , National Bureau of Standards Special Publication

633, U.S. Government Printing Office (1985).

Schwartz, R. B. and Eisenhauer, C. M., The Design and Construction of a D

2

0-Moderated 252Cf source for Calibrating Neutron Personnel Dosimeters

Used at Nuclear Power Reactors , NUREG/CR-1204, U.S. Nuclear Regulatory

Commission, Washington, D.C. (1980)

U.S. Department of Energy, Department of Energy Standard for the Performance

Testing of Personnel Dosimetry Systems , D0E/EH-0027, Washington, D.C.

(1986).

61

NIST-114A

(REV. 3-89)

U.S. DEPARTMENT OF COMMERCE

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY

BIBLIOGRAPHIC DATA SHEET

1. PUBLICATION OR REPORT NUMBER

NIST/SP-812

2. PERFORMING ORGANIZATION REPORT NUMBER

3. PUBUCATION DATE

August 1991

4. TITLE AND SUBTITLE

Criteria for the Operation of Federally-Owned Secondary Calibration

Laboratories (Ionizing Radiation)

5. AUTHOR(S)

Criteria Writing Group, E. H. Eisenhower, Chairman

6. PERFORMING ORGANIZATION (IF JOINT OR OTHER THAN NIST, SEE INSTRUCTIONS)

U.S. DEPARTMENT OF COMMERCE

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY

GAITHERSBURG, MD 20899

7. CONTRACT/GRANT NUMBER

8. TYPE OF REPORT AND PERIOD COVERED

Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (STREET, CITY, STATE, ZIP)

Same as item #6

10. SUPPLEMENTARY NOTES

DOCUMENT DESCRIBES A COMPUTER PROGRAM; SF-165, FIPS SOFTWARE SUMMARY, IS ATTACHED.

11. ABSTRACT (A 200-WORD OR LESS FACTUAL SUMMARY OF MOST SIGNIFICANT INFORMATION. IF DOCUMENT INCLUDES A SIGNIFICANT BIBLIOGRAPHY OR

LITERATURE SURVEY, MENTION IT HERE.)

This document contains standards of performance for laboratories that calibrate instrumentation used to

measure ionizing radiation. Such standards are useful for the development of a secondary level of

calibration laboratories that can provide a high-quality link between the National Institute of Standards

and Technology and those who make routine measurements at the field level. These standards may also

be used as criteria on which a decision is based regarding accreditation of a particular laboratory. They

were developed by representatives of federally-owned laboratories that perform calibrations of the type

addressed by the document. The first major part contains general criteria that must be satisfied by all

laboratories seeking accreditation. It includes requirements relating to management and staff, physical

aspects of the laboratory, calibrations facilities and equipment, operational procedures, accuracy and

quality assurance, and records and reports. Five subsequent major parts establish criteria for calibration

of survey instruments, irradiation of personnel dosimeters, calibration of sources, calibration of

instruments for diagnostic levels, and calibration of reference-class instruments. The types of radiation

covered include gamma rays, x rays, beta particles, neutrons, and alpha particles. An appendix describes

the proficiency tests administered by NIST to secondary laboratories as a prerequisite for their

accreditation.

12. KEY WORDS (6 TO 12 ENTRIES; ALPHABETICAL ORDER; CAPITALIZE ONLY PROPER NAMES; AND SEPARATE KEY WORDS BY SEMICOLONS)

accreditation; calibration; criteria; gamma rays; instruments; ionizing radiation;

measurements; proficiency tests; quality assurance; secondary laboratories;

standards; x rays

13. AVAILABILITY

UNLIMITED

FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE TO NATIONAL TECHNICAL INFORMATION SERVICE (NTIS).

X

X

ORDER FROM SUPERINTENDENT OF DOCUMENTS, U.S. GOVERNMENT PRINTING OFFICE,

WASHINGTON, DC 20402. ORDER FROM NATIONAL TECHNICAL INFORMATION SERVICE (NTIS), SPRINGFIELD, VA 22161.

14. NUMBER OF PRINTED PAGES

65

15. PRICE

ELECTRONIC FORM * U.S. G.P.O. : 1991-31 1 -891 :40048



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