Regulatory Guide 8.32

(Task OP 713-4), Criteria for Establishing a Tritium Bioassay Program

ML003739479
Person / Time
Issue date:	07/31/1988
From:	Office of Nuclear Regulatory Research
To:
References
RG-8.32
Download: ML003739479 (7)

U.S. NUCLEAR REGULATORY COMMISSION

V0, p~k REG4[,4 9,

1 g7

0,

A. INTRODUCTION

Section 20.108, "Orders Requiring Furnishing of Bioassay Serv ices," of 10 CFR Part 20, "Standards for Protection Against Radia tion," states that the Nuclear Regulatory Commission (NRC) may incorporate into a license provisions requiring a specific program of bioassay measurements as necessary or desirable to aid in deter mining the extent of an individual's exposure to concentrations of radioactive material.

This guide provides NRC staff guidance on:

1. The conditions under which the NRC staff will consider the need for license conditions related to tritium bioassays under

§ 20.108 of 10 CFR Part 20.

2. The scope, types, and frequency of tritium bioassay programs conducted by licensees for the purpose of demonstrating compliance with applicable provisions of 10 CFR Part 20 or for satisfying license conditions imposed under § 20.108. However, if this guide differs from the requirements of any existing license condition, the licensee should conform to such requirements until the license is amended in accordance with the Commission's regulations.

This guide provides criteria acceptable to the NRC staff for developing and implementing a bioassay program for any licensee handling or processing tritium' either as pure gas or in various chemical compounds. It further provides guidance to such licensees on selecting workers who should participate in a program to detect and measure possible internal radiation exposure. This guide is pro grammatic in nature and does not deal with measurement techniques and procedures.

2

'Tritium, an isotope of hydrogen, has a mass number of 3 (2 neutrons, 1 proton). Tritium may be symbolized or represented in the literature by the standard scientific symbol 3H or by other symbols adopted for convenience in publication such as hydrogen-3, H-3, or T.

2Sections 8 through 11 of ANSI N13.14-1983, "American National Stand ard for Dosimetry -Internal Dosimetry Programs for Tritium Exposure Minimum Requirements," contain some useful information on procedural aspects of bioassay programs. ANSI N13.14-1983 is available from the American National Standards Institute, Inc., 1430 Broadway, New York, NY 10018.

Any information collection activities mentioned in this regulatory guide are contained as requirements in 10 CFR Part 20, which pro vides the regulatory basis for this guide. The information collec tion requirements in 10 CFR Part 20 have been cleared under OMB

Clearance No. 3150-0014.

B. DISCUSSION

The topics treated in this guide include determinations of (1)

whether bioassay should be performed, (2) frequencies of bioassay,

(3) who should participate, (4) the actions to take based on bioassay results, and (5) the activity levels that should initiate such actions.

The information and references that were used in developing this guidance are summarized in NUREG-0938, "Information for Establishing Bioassay Measurements and Evaluations of Tritium Exposure." 3 NUREG-0938 also contains information that may be useful to applicants and licensees in planning and conducting bioassay programs for tritium.

The triggering concentrations given in Table 1 of this guide not withstanding, licensees are not exempt from the air sampling and bioassay requirements of 10 CFR Part 20; particular attention should be given to paragraphs 20.103(a)(3) and 20.103(c)(2). Paragraph

20.103(a)(3) requires licensees to measure radioactivity concentra tions in the air and, as appropriate, to use bioassay measurements for the timely detection and assessment of individual intakes of radioactivity. Paragraph 20.103(c)(2) requires licensees to provide bioassays as appropriate to evaluate actual exposures when the licensee wishes to make allowance for the use of respiratory pro tection equipment in estimating exposures of individuals to airborne radioactive material. The "appropriateness" of conducting bioassays to comply with paragraphs 20.103(a)(3) and (c)(2) must be judged on a case-by-case basis. For example, if the Table 1 concentration criteria are routinely met, but there are unexpectedly high air sam pling results, bioassays may be "appropriate" in order to verify and assure that regulatory intake limits have not been exceeded.

3NUREG-0938 is available from The Superintendent of Documents, U.S.

Government Printing Office, P.O. Box 37082, Washington, DC 20013-7082;

or from the National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161.

USNRC REGULATORY GUIDES

The guides are issued in the following ten broad divisions:

Regulatory Guides are issued to describe and make available to the public methods acceptable to the NRC staff of implementing

1. Power Reactors

6. Products specific parts of the Commission's regulations, to delineate tech-

2. Research and Test Reactors

7. Transportation niques used by the staff in evaluating specific problems or postu-

3. Fuels and Materials Facilities

8. Occupational Health lated accidents, or to provide guidance to applicant

s. Regulatory

4. Environmental and Siting

9. Antitrust and Financial Review Guides are not substitutes for regulations, and compliance with

5. Materials and Plant Protection 10. General them is not required. Methods and solutions different from those set out in the guides will be acceptable if they provide a basis for the findings requisite to the issuance or continuance of a permit or Copies of issued guides may be purchased from the Government license by the Commission.

Printing Office at the current GPO price. Information on current GPO prices may be obtained by contacting the Superintendent of This guide was issued after consideration of comments received from Documents, U.S. Government Printing Office, Post Office Box the public. Comments and suggestions for improvements in these

37082, Washington, DC 20013-7082, telephone (202)275-2060 or guides are encouraged at all times, and guides will be revised, as

(202)275-2171.

appropriate, to accommodate comments and to reflect new informa tion or experience.

Issued guides may also be purchased from the National Technical Written comments may be submitted to the Rules and Procedures Information Service on a standing order basis. Details on this Branch, DRR,

ADM,

U.S.

Nuclear Regulatory Commission, service may be obtained by writing NTIS, 5285 Port Royal Road, Washington, DC 20555.

Springfield, VA 22161.

REGULATORY GUIDE

OFFICE OF NUCLEAR REGULATORY RESEARCH

REGULATORY GUIDE 8.32 (Task OP 713-4)

CRITERIA FOR ESTABLISHING A TRITIUM BIOASSAY PROGRAM

July 1988

Table 1 ACTIVITY LEVELS OR CONCENTRATIONS ABOVE WHICH

TRITIUM BIOASSAY PROGRAMS SHOULD BE PROVIDED

HTO Mixed with More HTOb and Other Tritiated Tritium (HT or T2)c Than 10 kg of Inert Compounds (Including Gas in Sealed H20 (e.g., in Reactor Types of Operationa Nucleotide Precursors)

Process Vesselsd Coolant)e Processes in open room or bench with possible escape of

0.1 Ci

100 Ci

0.01 Ci/kg tritium from process vessels Processes with possible escape of tritium carried out within

1 Ci

1,000 Ci

0.1 Ci/kg a fume hood of adequate design, face velocity, and performance reliability Processes carried out within gloveboxes that are ordinarily

10 Ci

10,000 Ci I Ci/kg closed but with possible release of tritium from process vessels and occasional exposure to contaminated box and leakage aQuantities (< 10 kg) of substances containing tritium that are present during operations may be considered to be either the amount processed by an individual at any one time (when accidental intake is more likely) or the amount of activity that entered into the process (throughput) during any one month (when routine handling of repeated batches is the more likely source of exposure).

bHTO is a symbol for a water molecule in which a tritium atom (T) is present in place of a normal hydrogen atom (H).

CA molecule of hydrogen gas contains two hydrogen atoms. Either one of these atoms may be replaced with T to form HT, or two T atoms may combine to form T2 gas.

dThis assumes that adequate air monitoring has established that there is no tritium leakage or that no significant amount of tritium gas can be converted to HTO before intake.

eThis column is applicable in place of the previous two columns in cases where tritium can be identified at measurable concentrations in large amounts of water or other substances, such as at nuclear power plants.

For the user's convenience, the following terms are presented with their definitions as used in this guide:

Bioassay-The determination of the kind, quantity or concen tration, and location of radioactive material in the human body by direct (in vivo) measurement or by analysis (in vitro) of materials excreted or removed from the body. Only in vitro analysis of urine (or, if more convenient, another representative body fluid) is applicable to tritium or its compounds.

Intake-The total quantity of radioactive material entering the body.

Uptake-The total quantity of radioactive material retained in the body (i.e., not immediately exhaled) after an intake.

C. REGULATORY POSITION

1. CONDITIONS UNDER WHICH BIOASSAY

IS NECESSARY

1.1. Routine bioassay is necessary when quantities of tritium processed by an individual at any one time or the total amounts processed per month exceed those shown in Table 1 for each form of tritium.

1.2. For workers in nuclear reactor facilities, urine bioassay should be performed when the concentrations of tritium in the reactor coolant water exceed those shown in the right-hand column of Table 1. The lowest value in Table 1, 0.01 Ci/kg of coolant, should be used to initiate a bioassay program whenever employees are exposed to the air in a room or area where more than 10 kg of water containing this or greater concentration or a total of more than 0.1 Ci of tritium is in contact with the air (such as a storage pool). If exposure to water containing a concentration of tritium greater than or equal to 1 Ci/kg is expected, such as when leakages occur, a bioassay program should be initiated because significant intakes, both by inhalation and by absorption of water vapor through the skin, can occur when individuals are exposed to tritium at these concentrations.

1.3. Bioassays should also be performed when an employee can come into skin contact with, ingest, or absorb into the body through cuts, abrasions, or accidental (hypodermic) injection, water or any other substance with concentrations of tritium greater than or equal to 0.01 mCi/kg (0.01 1iCi/cc) such as may be common in laboratory applications.

8.32-2

2. PARTICIPATION

All workers involved in the processing of tritium under condi tions specified in Regulatory Position 1 or in the environs of the process should participate in the bioassay program.

3. TYPES OF BIOASSAY THAT SHOULD BE

PERFORMED

3.1 Baseline (Preemployment or Preoperational)

A baseline bioassay of each worker should be conducted before that worker begins working with tritium in amounts that would require initiation of a bioassay program as specified in Regulatory Position 1.

3.2 Routine Regular bioassays should be conducted to monitor routine opera tions at frequencies specified in Regulatory Position 4.

3.3 Postoperational and with Termination Physical Examination A bioassay should be performed within one month after the last possible exposure to tritium, when operations are being discon tinued, or when the worker is terminating activities with potential exposure as indicated by the criteria in Table 1.

3.4 Diagnostic A followup bioassay should be performed as soon as possible but not later than one week after any sample exceeding levels given as action points in Regulatory Position 5 in order to confirm the initial results and, in the case of a single intake, to allow an estimate of the effective half-life of the tritium in the body. If the initial sam ple or other data indicates a possible exposure high enough to war rant immediate medical attention, complete and immediate followup should be conducted as described in Regulatory Position 5.1.3.

4. FREQUENCY OF SAMPLING

4.1 Initial Routine A bioassay sample should be taken within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, if possible, but not later than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following entry of an individual into an area where operations require bioassay according to Regulatory Position 1. Sam1 tes should then be taken every two weeks or more frequently as long 2s the individual is working with tritium. When work with tritium is on an infrequent basis (less frequently than every two weeks), bioassay should be performed within ten days of the end of the work period during which tritium was handled.

Samples should not be collected until two hours after termination of the potential exposure in order that bladder contents will have had time to equilibrate with other body water.

4.2 After Three Months A sampling frequency selected in accordance with Regulatory Position 4.1 may be changed to quarterly it, after three months, the following three conditions are met:

4.2.1 The average urinary tritium concentration in specimens obtained from the worker during the three-month period does not exceed 3 p.Ci/L,

4.2.2. If measurements of the concentration of tritium in air are required as a condition of the license, the quarterly average con centration (pCi/mL) to which workers are exposed multiplied by the factor 6.3 X 108 mL does not exceed 0.8 mCi, and

4.2.3. The working conditions during the three-month period, with respect to the potential for tritium exposure, are representative of working conditions during the period in which a quarterly urinalysis frequency is employed, and there is no reasonable expectation that the criteria given in items 4.2.1 and 4.2.2 above will be exceeded.

5. ACTION POINTS AND CORRESPONDING ACTIONS

5.1 Biweekly or More Frequent Sampling

5.1.1. Whenever the intake of tritium within any 40-hour work period exceeds the amount that would be taken into the body from uniform exposure for 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> at the air concentration (5 X 10-6 fiCi/mL) specified in Table 1, Column 1, of Appendix B to 10 CFR

Part 20,4 the licensee is required to make evaluations, take necessary corrective actions, and maintain records as specified in paragraph

20.103(b)(2) of 10 CFR Part 20.

5.1.2. If urinary excretion concentrations exceed 5 fACi/L but are less than 50 fCi/L, the following course of action should be taken:

1. An investigation of the operations involved, including surveys and monitoring of air and surface contamination, should be carried out to determine the causes of the intake, and an evaluation of the potential for further larger in takes or of the possible involvement of other employees should be performed.

2. Any reasonable corrective actions that the investigation indicates may lower the potential for further exposures should be implemented.

3. A repeat urine sample should be taken within one week of the previous sample and should be evaluated within a

4Multiplying the concentration given in Appendix B, 5 x 10-6 pCi/mL, by

6.3 X 108 mL gives the corresponding quarterly intake limit of tritium by inhalation. In the case of inhaled HTO, which mixes instantly with other water molecules after entering body fluids, the intake may be assumed equal to uptake. The uptake of tritium (as HTO) by absorption through the skin is assumed equal to the uptake by inhalation unless the form of tritium in the air can be demonstrated to have lower uptakes. The total uptake, including skin absorption, would be assumed to be about 6.3 mCi, which delivers a dose commitment of about 1.25 rems to standard man (using the quality factor Q= 1.7). A 40-hour occupational exposure at a concentration of

5 X 10-6 yCi/mL would thus result in an intake of 6.3/13 =0.48 mCi and a dose commitment of about 0.1 rem. An acute intake (in less than one day)

of 0.48 mCi would result in an initial body water concentration of about

11 piCi/L. (The use of Q = 1.7 in this example follows the practice used in developing concentration limits for the current 10 CFR Part 20. Changes in recommendations of various committees and a review of quality factor determinations reported in the literature are presented in NUREG-0938.)

8.32-3

week after collection. Internal dose commitments should be estimated using at least these two urine sample evalua tions and other survey data, including the probable times of the intake of tritium.

4. Any evidence indicating that further work in the area might result in an employee receiving a dose commitment in excess of the limits established in § 20.101 should serve as cause to remove the employee from work in this opera tion until the source of exposure is discovered and corrected.

5. Reports or notifications must be provided as required by

§§ 20.405, 20.408, and 20.409 of 10 CFR Part 20 or as required by conditions of the license pursuant to § 20.108 of 10 CFR Part 20.

5.1.3. If urinary excretion concentrations exceed 50 pCiIL, the following course of action should be taken:

1. Carry out all steps in Regulatory Position 5.1.2.

2. If the projected dose commitment exceeds levels for the whole body as provided in § 20.403 of 10 CFR Part 20,

notify the NRC as appropriate.

3. Refer the case to appropriate medical and health physics consultants for recommendations regarding the need for immediate therapeutic procedures that may be carried out to accelerate removal of tritium from the body.

4. Carry out repeated sampling at approximately one-week intervals at least until urine samples show concentrations less than 5 pCiIL. If there is a possibility of long-term organic compartments of tritium that require evaluation (see NUREG-0938), continue sampling as long as necessary to ensure that appreciable exposures to these other compartments do not go undetected and to provide estimates of total dose commitments.

5.2 Quarterly Sampling Carry out the actions called for when any of the action levels indicated in Regulatory Position 5.1 are exceeded. In addition, institute biweekly (or more frequent) sampling for at least the next six-month period, even when urinary concentrations fall below 5 jACiIL.

D. IMPLEMENTATION

The purpose of this section is to provide information to applicants and licensees regarding the NRC staff s plans for using this regulatory guide.

Except in those cases in which an applicant or licensee proposes an acceptable alternative method for complying with specified portions of the Commission's regulations, or cases in which dif ferent requirements are imposed by any existing license condition, the methods described in this guide will be used in evaluating the need for license conditions related to tritium bioassay programs and in evaluating the radiation protection programs of licensees that have bioassay requirements incorporated in their licenses in accordance with § 20.108 of 10 CFR Part 20. This guide will also be used in evaluating changes to existing bioassay programs that may be re quested by licensees.

8.32-4

BIBLIOGRAPHY

American National Standards Institute, "American National Standard for Dosimetry--Internal Dosimetry Programs for Tritium Exposure-Minimum Requirements,"

ANSI

N13.14-1983,1 1983.

Brodsky, A., "Information for Establishing Bioassay Measure ments and Evaluations of Tritium Exposure," NUREG-0938,2 U.S.

Nuclear Regulatory Commission, Washington, DC,

1983.

Duijsings, J. H., et al., "Internal Contamination of Radio logical Workers by Tritium Compounds at Two Universities in the Netherlands," Health Physics, Vol. 46, pp. 665-669,

1984.

International Commission on Radiological Protection, "Limits for Intakes of Radionuclides by Workers," ICRP-30,' Part 1, 1979.

'Copies of ANSI standards may be purchased from The American National Standards Institute,

1430 Broadway, New York, NY

10018.

2Copies may be purchased from the U.S. Government Printing Office, Post Office Box 37082, Washington, DC 20013-7082.

3Copies may be purchased from Pergamon Press, Inc., Maxwell House, Elmsford, NY 10523.

Johnson, J. R., "Frequency of Bioassay Monitoring for Internal Contamination and Its Relationship to Sensitivity and Accuracy Requirements," Health Physics, Vol. 46, p. 715, 1984.

Kinslow, R., J. J. Moschella, and C. N. Cawley, "A Model of Urinary Tritium Following Multiple Contaminations,"

Health Physics, Vol. 46, pp. 1154-1155, 1984.

Minister of National Health and Welfare of Canada, "General Guidelines for Bioassay Programs," Bioassay Guideline 1, Report

80-EHD-56, 4 1980.

Minister of National Health and Welfare of Canada, "Bioassay Guide line 2, Guidelines for Tritium Bioassay," Report 83-EHD-87, 4 1987.

Myers, D. K., and J. R. Johnson, "Estimating the Biological Hazards of Tritium," Health Physics, Vol. 46, p. 715, 1984.

Smith, L. R., et al., "Human Execretion Patterns Following Occupational Uptake of 3H, 14C, and 35S-Labelled Compounds,"

Health Physics, Vol. 44, pp. 221-234, 1983.

4Copies may be obtained from the Minister of National Health and Welfare of Canada, Radiation Protection Bureau, Brookfield Road, Ottawa, Ontario KlA IC1, Canada.

8.32-5

VALUE/IMPACT STATEMENT

A draft value/impact statement was published with Draft Regulatory Guide OP 713-4 when the draft guide was published for public comment in June 1983. No changes were necessary, so a separate value/impact statement for the final guide has not been prepared. A copy of the draft value/impact statement is available for inspection and copying for a fee at the Commission's Public Document Room at 1717 H Street NW., Washington, DC, under Task OP 713-4.

8.32-6

UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555 FIRST CLASS MAIL

POSTAGE & FEES PAID

USNRC

PERMIT No. G 67 OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE, $300

-1

-