Regulatory Guide 4.13

Performance,Testing & Procedural Specifications for Thermoluminescence Dosimetry:Environmental Applications

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Issue date:	07/31/1977
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July REGULATORY GUIDE

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REGULATORY GUIDE 4.13 PERFORMANCE, TESTING, AND PROCEDURAL SPECIFICATIONS

FOR THERMOLUMINESCENCE DOSIMETRY:

ENVIRONMENTAL APPLICATIONS

A. INTRODUCTION

Section 20.105, "Permissible levels of radiation in unrestricted areas," of 10 CFR Part 20, "Standards for Protection Against Radiation," provides limits on levels of radiation in unrestricted areas resulting from possession, use, or transfer of NRC-licensed radioac tive material. Section 20.201, "Surveys," of 10 CFR

Part 20 further requires that a licensee conduct sur veys as may be necessary to comply with the regula tions of 10 CFR Part 20 including, when appropriate, the measurement of levels of radiation.

Paragraph IV.B(2) of Appendix I, "Numerical Guides for Design Objectives and Limiting Condi tions for Operation to Meet the Criterion 'As Low As Is Reasonably Achievable' for Radioactive Material in Light-Water-Cooled Nuclear Power Reactor Ef fluents," to 10 CFR Part 50, "Licensing of Produc

,,

tion and Utilization Facilities,"

requires that licensees establish appropriate surveillance and monitoring programs to provide data on measurable levels of radiation and radioactive materials in the en vironment.

General Design Criterion 64, "Monitoring radioactivity releases," of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10

CFR Part 50 requires that nuclear power plant designs provide means for monitoring the plant en virons for radioactivity that may be released as the result of normal operations, including anticipated operational occurrences, and as the result of postulated accidents.

Thermoluminescence dosimetry (TLD) is widely used to measure levels of X and gamma radiation in the environs of NRC-licensed nuclear facilities. This guide provides minimum acceptable performance criteria for TLD systems used for this purpose. It also provides procedures for calibration, field application, and reporting. It does not apply to TLD systems used for the purpose of determining occupational ex posure.

B. DISCUSSION

Working Group 9 of the Health Physics Society Standards Committee for American National Stan dards Institute (ANSI) Committee N 13 on Radiation Protection has prepared a standard that specifies minimum acceptable performance of TLDs used for environmental measurements; outlines methods to test for compliance; and provides procedures for calibration, field application, and reporting. This standard was approved by the N13 Committee. It was subsequently approved and designated N545

1975, by ANSI on August 20, 1975.1 The specification of performance criteria of ther moluminescence dosimetry and the verification of the actual performance require appropriate statistical concepts and techniques. Because wide applicability is intended, ANSI N545-1975 as well as the provi sions and clarifications given below in the regulatory position are confined to simple statistical concepts and prescribe no specific statistical techniques. In fact, the implementation of some specifications by rigorous statistical methods may prove difficult for some users of the guide. Therefore, good approx imate statistical methods are acceptable.

• Lines indicate substantive changes from previous issue.

'ANSI

N545-1975,

"Performance, Testing, and Procedural Specification for Thermoluminescence Dosimetry (Environmental Applications)" may be obtained from the American National Standards Institute, 1430 Broadway, New York, New York

10018.

I*

USNRC REGULATORY GUIDES

Comments should be sent to the Secretary of the Commission, US. Nuclear Regu latory Commission, Washington, D.C.

20555. Attention:

Docketing and Service Regulatory Guides are issued to describe and make available to the public methods Branch.

acceptable to the NRC staff of implementing specific parts of the Commission's regulations, to delineate techniques used by the staff in evaluating specific problems The guides are issued in the following ten broad divisions or postulated accidents, or to provide guidance to applicants. Regulatory Guides are not substitutes for regulations, and compfiance with them is not required.

1. Power Reactors

6. Products Methods and solutions different from those set out in the guides will be accept-

2. Research and Test Reactors

7. Transportation able if they provide a basis for the findings requisite to the issuance or continuance

4. Environmental and Siting

9. Antitrust Review of a permit or license by the Commission.

5. Materials and Plant Protection

10. General Comments and suggestions for improvements in these guides are encouraged at all Requests for single copies of issued guides (which may be reproduced) or for place times, and guides will be revised, as appropriate, to accommodate comments and ment on an automatic distribution list for single copies of future guides in specific to reflect new information or experience.

This guide was revised as a result of divisions should be made in writing to the US. Nuclear Regulatory Commission, substantive comments received from the public and additional staff review, Washington, D.C.

20555, Attention Director. Oivision of Document Control Revision 1

1977

No specific criteria for good approximation are prescribed. However, the user should judge whether the sample size is adequately large for the approxima tion and whether the distribution of the measure ments is sufficiently close to that assumed in the analysis. Problems relating to underlying distribu tions can be avoided by the use of nonparametric methods. Some of the specifications that are stated in terms of standard deviations can be reformulated in nearly equivalent specifications for tolerance limits for which simple nonparametric methods are available. Such reformulations are also acceptable.

A. Hald2 and W. J. Conover3 are useful reference sources for parametric and nonparametric methods, respectively.

If every TLD is individually calibrated, the popula tion parameters for certain errors can be computed directly, and statistical inference is not needed for specifications relating to these errors.

Comments received on this guide and subsequent discussions of these comments have indicated a need for the following emphasis on, or clarification of, sec tions of the guide and ANSI N545-1975 in order to avoid misinterpretations:

a. In this guide, the expression environs of NRC

licensed facilities includes both the term environment as defined in ANSI N545-1975 and the phrase un restricted areas as defined in 10 CFR Part 20.

b. In Section 2, "Definitions," of ANSI N545

1975, the distinction between thermoluminescence dosimeter (TLD) and thermoluminescence (TL)

phosphor should be noted. As defined in ANSI N545

1975, a TLD can, and usually does, contain multiple TL phosphors or. otherwise provides for multiple readings of the exposure. When multiple readings are used for the measurement of the response of a TLD,

that response is an average of the individual readings.

ANSI N545-1975 refers to these average values rather than to the individual readings.

c. Regulatory position 3 of this guide and Section

3.3 of ANSI N545-1975 refer to the overall error in the total field exposure. No method is specified for interpreting field exposures to isolate contributions attributable to a nuclear facility, and no limit is specified on the error associated with estimates of the exposure attributable to the facility.

d. Section 6.3.1 of ANSI N545-1975 specifies field exposure at a height of 1 meter above the ground;

however, Section 6.3.3 permits exposure at other heights.

2A. Hald, Statistical Theory with Engineering Applications, John Wiley & Sons, Inc., 1952.

3W.J. Conover, Practical Nonparametric Statistics, John Wiley &

Sons, Inc., 1971.

e. Section 7.2 of ANSI N545-1975 permits the re quirements of Section 4 of the standard to be satisfied by reference to prior documents. Test results provided by vendors are examples of such docu ments. Therefore, when requirements of Section 4 of the standard can be met by reference to test results provided by a vendor or other source, additional tests by a licensee are not needed.

f. The appendixes to ANSI N545-1975 are not a part of the ANSI standard or of this regulatory guide, which endorses the standard. However, the appen dixes do provide useful information on the topics covered.

C. REGULATORY POSITION

The requirements and recommendations for per formance specifications, testing procedures, calibra tion procedures, field procedures, and reporting procedures that are included in ANSI N545-1975 are generally acceptable to the NRC staff as the basis for using thermoluminescence dosimetry for the measurement of X and gamma radiation in the en virons of NRC-licensed facilities subject to the fol lowing additional provisions and qualifications.

1. Section 3, "Performance Specifications,"

of ANSI N545-1975 should be supplemented by the fol lowing statement: "Subsection 4.2.4 shall apply also to the subsections 3.1 and 3.3."

2. Instead of Section 3.1 of ANSI N545-1975, the following should be used: "The performance of the TLD system shall be determined under laboratory conditions and in a known radiation field with an ex posure equal to that resulting from an exposure rate of 101MR/hr during the field cycle. Ninety-five per cent of the measurements shall fall within 10% of the known exposure."

3. Instead of Section 3.3 of ANSI N545-1975, the following should be used: "Ninety-five percent of the final values (after all appropriate corrections to the measurements are applied, including those for errors expected under field conditions) shall differ from the correct value by less than 30% of the correct value."

4. Instead of Section 4.3.1 of ANSI N545-1975, the following should be used: "Uniformity shall be determined by giving TLDs from the same batch an exposure equal to that resulting from an exposure rate of lOtR/hr during the field cycle. The response obtained shall have a relative standard deviation (coefficient of variation) of less than 7.5%."

5. Instead of Section 4.3.2 of ANSI N545-1975, the following should be used: "Reproducibility shall be determined by giving one TLD repeated exposures equal to that resulting from an exposure rate of 10

juR/hr during the field cycle. The responses shall have

4.13-2

a relative standard deviation (coefficient of variation)

of less than 3.0%."

D. IMPLEMENTATION

The purpose of this section is to provide informa tion to applicants and licensees regarding the NRC

staff's plans for using this regulatory guide.

This guide reflects current NRC staff practice.

Therefore, except in those cases in which the appli cant or licensee proposes an acceptable alternative method, the staff is using and will continue to use the method described herein in evaluating an applicant's or licensee's capability for and performance in com plying with specified portions of the Commission's regulations until this guide is revised as a result of suggestions from the public or additional staff review.

4.13-3 I

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