Regulatory Guide 6.5

General Safety Standard for Installations Using Nonmedical Sealed Gamma-Ray Sources

ML003739243
Person / Time
Issue date:	06/30/1974
From:	Office of Nuclear Regulatory Research
To:
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RG-6.5
Download: ML003739243 (2)

A. INTRODUCTION

Section 20.101, "Exposure of Indcividuals to Radia tion in Restricted Areas," of 10 CFR Part 20, "Stand ards for Protection Against Radiation," provides that, subject to certain enumerated exceputios, no licensee shall xces, use, or transfer licensed material in such a manner as to cause any indiidual in a restncted area to receive a dose in excess of the limits specified therein.

Paragraph (c) of §20.1 provides that licensees, in addition to complying with the requirements set forth m Part 20, should make every reasonable effort to maintain radiation exposures as far below the limits specified in Part 20 as practicable.

This guide describes general safety practices which are acceptable to the Regulatory staff a methods for nonmedical users of sealed garnrna-ray sources to corn ply, in part, with the above Commrnission regulations.

Basic to this general safety standard are the use of appropriate equipment, ample shielding, and safe oper ating procedures.

B. DISCUSSION

American National Standards Institute Subcommittee N43-5 has revised National Bureau of Standards Hand book 93, "Safety Standard for Non-Medical X-Ray and Sealed Gamma-Ray Sources," and the revised standard, designated ANSI N543-1974 1 and now entitled "Gen eral Safety Standard for Installations Using Non-Medical X-Ray and Sealed Gamma-Ray Sources," was approved by the American National Standards Institute in 1974. The standard provides recommendations for appropriate

'Copwe., ma, bc o bý3 aied fromtn the A-,mencan NationaJ Standards Inst:lutc, In,.. '430 ay, Nevttr York, Ne'S r York 10018.Jun8e 1974 GUIDE equipment, shielding, and operating procedures.

Con tamied in appendixes to the standard are guiddTce and extensive data for use in deter-rruruuon of se d barrier thicknees for inrstallatcon.s usiig XVra,, e-uip mernt or sealed sources of cobaJt-6,0.

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C. REGULATORY

POSITION The requirements and recommended practices con tamed in ANSI N543 1 are acceptable for the construc tion and use of installations unng sealed pmma-ra> sources for nonmedical purposs subject to the follo,.w ing: 1. Table I of ANSI N543 lists maximum permissible dose lirmts. In lieu of those listed limits, the user of this guide should refer to the dose limits prescribed by 10 CFR Part 20, -Standards for Protection Against Radiation." Every reasonable effort shoulc be made to maintain radiation exposures as far below these lirris as practicable.

2. The words "Cauton" and "Danger" may be used intrchan ably on warning

3. Paragraph

3.1.7 of ANSI N5-43 implies that osees oi" rrdlLhrerns in any one hour and 100 rrnllirerns in an;. seven consecutive days are absoluute hrruts imposed the Comrmssion for expcoures in unrestnrcted areas. The user of this guide is directed to §20.105(a)

of 10 CFR Part 20 which provides that, Lnder certair conditions, the Commission will approve dos hmits greater than 2 millirems mn any one hoJr and 10C millirems in an', seven consecuove days

4. Paragraphs

3.2.5 and 3.4.3 of ANSI .N543 ,rpl. a dose rate of 5 mdllirems per hour is tre on., USAEC REGULATORYf GUIDES COP~-" Of ;.0Vp.dS qW 'd" L, OCý@ W t" 14,0a, N~ -e' -,, Rmqa~o, G ,4j 11ý 100ý tw 1d o tV >bC 0"'sdto "N4 ,S, Atc'-c Ewe-, Co,- 16,,0a owh-rc 2a1to' .A IV,'. h ~ .4,. C C-#~c tb. aý ,~ .~ o '.~, Am*!, ,"o D0 CO 00 Rp, t.-ao,- S'- Co,.-ý',..

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REGULATORY

DIRECTORATE

OF REGULATORY

STANDARDS

REGULATORY

GUIDE 6.5 GENERAL SAFETY STANDARD FOR INSTALLATIONS

USING NONMEDICAL

SEALED GAMMA-RAY

SOURCES

craterion for determining a radiation area. The user of Or-' guide is directed to §20.202(bX2)

of 10 CFR P.j, r 20 which provides that does levels of either 5 mhlirenis in any one hour or 100 miliirems in any 5 c,,iseculive days may be used to determine a radiaarea 5. Ii addition to the rate of exposure provisions in paragraph

3.3.3 of ANSI N543, the user of this guide is directed to the requirements of 10 CFR 20.105, "Per-missible Levels of Radiation Exposure in Unre stricted Areas." The requirements of §20.105 should also be considered when applying Appendix B of ANSI N543, "Determination of Gamma Ray Shield ing Barrier Thicknesses."

6. Piragraph

6.5.2 of ANSI N543 permits the use of a suitable lock in place of an interlock for a temporary exposure room. The user of this guide should comply with the specific provisions of §§20.203(cX2Xiii)

and 2O.203(cX4)

of 10 CFR Part 20 if he elects to use a lock in place of an interlock.

7. Paragraph

7.2 of ANSI N543 lists cqanges which require a radiation protection resurvey or reevalua tion by a qualified expert. A resurvey or reevaluation should also be performed when a change in radiation source may have adversely affected radiation protec tion.

8. Paragraph

8.4.6 of ANSI N543 recommends consider ation of the guidance provided in ANSI N13.6-1966(R1972), "American National Standard Practice for Occupational Radiation Exposure Records Systems." The user of this guide should also consider Regulatory Guide 8.7, "Occupational Radia tion Exposure Records Systems," which provides an acceptable definition of "bioassay" and notes that records must be maintained in accordance with §20.401 of 10 CFR Part 20. 9. Appendix A of ANSI N543 proides guidance for planning shielding where adequate occupancy data are not available or when complete installation use data are not available.

Persons using the occupancy factors and use factors in Appendix A for planning purposes should make appropriate observations and records to substantiate use of factors less than 1.2 L