Revision 1 

August 1988 U.S. NUCLEAR REGULATORY COMMISSION

REGULATORY GUIDE 

OFFICE OF NUCLEAR REGULATORY RESEARCH 

REGULATORY GUIDE 8.22 

(Task OP 013-4 ) 

BIOASSAY AT URANIUM MILLS

A. INTRODUCTION 

Section 20.108, "Orders Requiring Furnishing of Bio

assay Services," of 10 CFR Part 20, "Standards for Protec

tion Against Radiation," states that, where necessary or 

desirable in order to aid in determining the extent of an 

individual's exposure to concentrations of radioactive mate

rial, the NRC may incorporate appropriate provisions in any 

license directing the licensee to make available to the indi

vidual appropriate bioassay services. Paragraphs 20.103(a)(I ) 

and 20.103(a)(2) require licensees to limit intakes of ma

terials such as uranium by individuals in restricted areas to 

the limits specified in Appendix B to 10 CFR Part 20. As 

specified in paragraph 20.103[a)(3), compliance with these 

limits must be determined through air sampling and, as 

appropriate, through bioassays. 

Paragraph 20.103(b)(2) permits licensees to make 

allowance for the use of respiratory protection equipment 

in determining the magnitude of intake provided such 

equipment is used as stipulated in paragraphs 20.103vc) 

through (g). These paragraphs require the licensee to 

perform bioassays, as appropriate, to evaluate individual 

exposure and to assess the protection actually provided. 

Respiratory protection devices do not always offer efficient 

protection. If a device is defective, is inappropriate for the 

particular contaminant involved, does not fit the wearer 

properly, or is carelessly put in place. the wearer may 

unknowingly receive a significant inhalation exposure. 

Therefore, if the potential intake was sufficiently large, 

bioassay procedures should be performed to determine 

whether such devices were in fact effective. 

This guide describes a bioassay program acceptab'e to the 

NRC staff for uranium mills (and applicable portions of ura

nium conversion facilities where the possibility of exposure 

to yellowcake dust exists), including exposure conditions 

with and without the use of respiratory protection devices.

Any information collection activities mentioned in this 

regulatory guide are contained as requirements in 10 CFR 

Part 20, which provides the regulatory basis for this guide. 

The information collection requirements in 10 CFR Part 20 

have been cleared under OMB Clearance No. 3150-0014. 

B. DISCUSSION 

This guide is based on information from the references, 

public comments received on the versions published in 

July 1978 and January 1987, data submitted by the milling 

industry, and an analysis by the staff of the Office of 

Nuclear Regulatory Research (NUREG-0874, "Internal 

Dosimetry Model for Applications to Bioassay at Uranium 

Mills," Ref. 1). Information acquired in the future may 

result in revisions to this guide; in particular, if bioassay 

results accumulated over a sufficiently long period of time 

indicate that workers at uranium mills are being adequately 

protected from airborne uranium by means of ventilation 

equipment and effective air sampling programs, the guide 

may be revised accordingly. 

C. REGULATORY POSITION 

1. DEFINITIONS 

Recent solubility studies have revealed notable differ

ences in the dissolution rates of yellowcake produced under 

different thermal conditions. For the purpose of this guide, 

the following distinction is made: 

a. Low-fired yellowcake is defined as yellowcake dried 

at temperatures less than 400' C. 

b. High-fired (calcined) yellowcake is defined as yellow

cake dried at temperatures of 400° C or more.

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 

nlques 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 applicants. Regulatory 4. Environmental and Siting 9. Antitrust and Financial Review 

Guides are not substitutes for regulations, anc 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 Rort Royal Road, 

Washington, DC 20555. Sprinofield, VA 22161.
Two important areas in a uranium mill where workers 

are exposed to uranium are defined as follows: ' 

a. Ore-dust areas, under normal conditions, are defined 

as those areas beginning with the transfer of ore from 

the ore pad to the crusher through the final thicken

ing stage of the leaching operation. 

b.'Yellowcake areas are defined as those areas that 

contain uranium extracted from the ore in a solution 

form from the ion exchange or solvent extraction 

stage through final packaging. 

2. WORKING CONDITIONS UNDER WHICH BIOASSAYS 

SHOULD BE PERFORMED 

Routine bioassays are considered by the NRC staff to be 

necessary for workers (1) routinely exposed to airborne yel

lowcake or directly involved in maintenance tasks in which 

yellowcake dust may be produced or (2) routinely exposed 

to airborne uranium ore dust. Baseline urinalysis bioassays 

should be performed for each worker prior to initial assign

ments for such work. Bioassays should be performed if there 

is any reason to suspect an inhalation exposure exceeding that 

resulting from exposure to an average yellowcake concentra

tion2 of 10"-'° ,Ci/mL (3.7 x 10-6 Bq/mL) for a 40-hour 

workweek or to an average ore-dust concentration of 10- 10 

;,Ci/mL (3.7 x 10.6 Bq/mL) (based on the concentration of 

gross alpha activity in air) for a period of 1 calendar quarter; 

if respiratory protection is used to maintain inhalation expo

sures below these quantities, bioassay should be performed 

to verify the effectiveness of the respirators. 

3. TYPES OF BIOASSAY 

Urinalysis should be performed to monitor exposures to 

uranium in ore dust as well as in yellowcake as they clear from 

the kidney before elimination renders them undetectable. In 

vivo thorax measurements should be made to detect the pres ence of (1) the more insoluble yellowcake component and (2) 

uranium in ore dust in the lung when air-sampling results indi

cate an exposure exceeding that resulting from exposure to 

such materials at an average concentration of 10.10 p.Ci/mL 

I f these definitions do not apply to a specific milling operation, 

the applicant may submit different definitions for consideration. 

2The 1 x 10-1 0 LOii/mL (3.7 x 10-' Bq/mL) value is not exactly consistent with the 0.2 mg/M 3 concentration limit for soluble ura nium in Footnote 4 of Appendix B to 10 CFR Part 20 because of 

the rounding off of values in Appendix B. Since the I x 10- I* 

JlCi/mL limit is more restrictive, this value has been used in the cal culation of all the action levels (weekly and quarterly) in this guide. For compliance purposes, Footnote 4 to Appendix B sets the weekly limit for soluble uranium compounds, which can be converted to 

radiological units using the specific activity of natural uranium (6.77 x 10"7 Ci/g or 2.5 x 104 Bq/g). As now defrmed in 10 CFR Part 20, the curie of natural uranium differs from the original definition in 

ICRP-2 (Ref. 2). The present definition of the curie of natural urani um in 10CFR Part 20 refers to the total activity of all uranium iso

topes in the natural uranium mixture. When natural uranriin- _e. fimed to be 0.711% by weight 2 3 sU and the 234U is assumed to be 

in secular equilibrium with 238U, 1 Ci of natural uranium is com posed of 0.489 Ci 13 4 U, 0.0225 Ci 231⁄2U, and 0.489 Ci '3"U. 

Actual percentages of 235U may be 0.711 ±0.1%.

(3.7 x 10-6 Bq/mL) (based on the concentration of gross 

alpha activity in air) in a period of 1 calendar quarter. 

4. FREQUENCY 

4.1 General Considerations 

The prescribed frequency of urinalysis and in vivo lung 

measurements is a function of the dissolution rates of the 

inhaled ore dust or yellowcake in the lungs. Workers in the 

yellowcake concentrate areas may be exposed to transient 

levels of airborne uranium that may cause chemical damage to 

the kidney. Therefore, urinalysis should be performed with 

sufficient frequency to detect such exposures before elimi

nation from the body renders them undetectable. Guidance 

on selecting appropriate frequencies is available in NUREG

0874 (Ref. 1). The applicant may use the simplified system 

of frequencies and action levels presented in this guide. 

4.2 Urinalysis for Workers from Yellowcake Areas 

Specimens from workers, regardless of whether or not res

piratory protection devices were used, should be collected 

and evaluated at least once per month, and additional 

special specimens should be collected and evaluated if for 

any reason an inhalation exposure exceeding that resulting 

from an exposure to an average yellowcake concentration 

of 10"10 pCi/mL (3.7 x 10-6 Bq/mL) for a 40-hour work

week is suspected or air sampling data are not available. 

4.3 Urinalysis for Workers from Ore-Dust Areas Exclusively 

Specimens from workers, regardless of whether or not 

respiratory protection devices were used, should be col

lected and evaluated at least once per month, and addi

tional special specimens should be collected and evaluated 

if for any reason an inhalation exposure exceeding that 

resulting from an exposure to an average ore-dust concen

tration of 10"10 pCi/mL (3.7 x 10.6 Bq/mL) (based on the 

concentration of gross alpha activity in air) for a period of 

1 calendar quarter is suspected. 

4.4 In Vivo Lung (Thorax) Measurements 

The lung counting procedure should be capable of 

detecting (at the lower limit of detection (LLD)) 9 nCi 

(330 Bq) or less of uranium in the lungs. 

When urinalysis results call for in vivo measurements (see 

Section 5), they should be performed as quickly as possible 

to determine if corrective measures are required. 

When air monitoring or exposure calculations call for in 

vivo measurements (see Section 3), they should be per

formed as quickly as practicable but no later than 3 months 

after such indication. 

4.5 Measurement Detection Limits 

The measurement sensitivity for urine analyses should be 

such that the LLD (for a probability of 0.05 for a Type I or a 

Type 1I statistical error) is 5 pg of uranium per liter of urine or

8.22-2
less (see Appendix A for an example of the determination 

of LLD). The LLD for uranium counting in vivo should be 

9 nCi (330 Bq) or less of uranium in the lungs. 

5. ACTION BASED ON BIOASSAY RESULTS 

Bioassay results should be promptly and carefully reviewed 

by qualified personnel, and appropriate action should be 

taken if the results exceed preselected levels. The corrective 

actions to be taken depend on the amount of uranium de

tected. Action levels and actions in Tables 1 and 2 are accept

able as a basis for a uranium mill bioassay program. Proposals 

for other action levels and actions from an applicant will be 

considered on a specific-case basis if accompanied by a de

scription of how the information in NUREG-0874 (Ref. 1) 

was used to derive those different criteria. 

It should be assumed that any, confirmed positive urinaly

sis results are an indication of soluble uranium to which the 

kidney has been exposed. 

5.1 Urinalysis for Workers from High-Fired-Yellowcake 

Areas 

The corrective actions to be taken depend on the 

amount of uranium detected and are given in Table 1. Fig

ure 1 and other information in NUREG-0874 (Ref. i) may 

be used to determine acceptable action levels for a single 

intake as a function of time for workers from high-fired

yellowcake areas. 

5.2 Urinalysis for Workers from Low-Fired-Yellowcake 

Areas 

The corrective actions to be taken depend on the 

amount of uranium detected and are given in Table 1. Fig

ure 2 and other information in NURFG-0874 (Ref. 1) 

may I, used to obtain acceptable action levels for a single 

intake as a function, of time for workers from low-fired

yeL•\\cake arela,. 

5.3 Urinalysis for Workers from Ore-Dust Areas Exclusively 

The corrcie - vion, to 1, taken depend on the 

amount o, uranium detected and are given in Table 1. Fig

ure 3 and information in NUREG-0874 (Ref. 1) may be 

used to obtain acceptable action levels for a single intake 

as a functior of time for workers from ore-dust areas. 

5.4 In Vivo 

It should be assumed that positive in vivo results indicate 

the quantity of uranium in relatively insoluble form that 

has accumulated in the lung- Corrective action should be 

taken in accordance with Table 2 of this guide. 

6. TIME OF SPECIMEN COLLECTION AND AVAIL

ABILITY OF RESULTS 

Routine and special urine specimens for analysis of 

uraniu::. compounds pertinent to mill operations should 

usual!\ be collected at least 36 hours after the most recent

occupancy in the mill. The 36-hour delay is necessary to 

avoid uranium that is eliminated without uptake in kidney 

tissues. (However, if compounds are encountered that mainly 

produce a very short-lived component, Morrow (Ref. 3, p. 6) 

recommends the use of two action levels: a 1 1jg/L Monday 

morning urinary excretion rate and an exposure-associated 

urinary output of 100 ,Ig/L during the first 24 hours after 

the exposure. Tables 1 and 2 would not necessarily be 

applicable to these results.) Sufficient volume should be 

collected for four analyses, each of which should be capable 

of achieving an LLD of 5 1ig/L (see Appendix A). 

Urinalysis results should be available to the person 

responsible for conducting the bioassay program within 

20 days after specimen collection. If the urinalyses are 

performed by an outside laboratory, results exceeding 35 

pg/L should be reported by telephone. 

In vivo results should be available to the person conduct

ing the bioassay program within 20 days after measure

ment. Results exceeding 16 nCi (590 Bq) should be re

ported by telephone. 

7. PREVENTION OF SPECIMEN CONTAMINATION 3 

7.1 Collection 

The specimens should be collected before the worker 

enters the work area and in an area free of uranium contam

ination. The collection may occur at an area outside the 

mill specifically designated to be maintained contamination 

free. The hands should be carefuliy washed prior to voiding. 

Disposable collection containers should be used. 

Under unusual circumstances where specimens cannot be 

collected in this manner, the worker should shower immedi

ately prior to voiding. When a showeris not possible, disposa

ble plastic or rubber gloves should be worn during voiding. 

7.2 Laboratory Analysis 

All laboratory analyses should be performed in a labora

tory essentially free of uranium contamination using 

containers and equipment essential]%- free of such contami

nation. Both on-site and off-site laboratories should main

tain the quality control procedures specified in Section 8 of 

this guide. Use of the laboratory, containers, and equip

ment for process or environmental samples should be 

restricted to low-level samples. (Note. The laboratory may 

be located within the restricted area provided these condi

tions are met.) 

7.3 In Vivo Counting Precautions 

For in vivo measurements, employee and clothing con

tamination are major sources of measurement bias. Care 

must be taken to minimize these factors. Only new clothing 

or clothing washed in a facility separate from those used for 

3The appropriate actions specified in Table 1 should be taken 

for any result that is confirmed by a second analysis even though 

specimen contamination is believed to be the cause of the elevated 

result.

8.22-3
potentially contaminated clothing should be worn during 

the in vivo measurement. If the in vivo measurement results 

indicate contamination, the subject should reshower, use 

clean clothing, and be recounted. 

8. QUALITY CONTROL 

A quality control program for bioassay measurements 

should be incorporated in each uranium mill bioassay 

program. A quality control program consistent with that 

recommended in the draft standard ANSI/HPS-N13.30 

(Ref. 4) will be acceptable. Alternatively, the following 

specific quality control program for bioassay at uranium 

mills will be acceptable. 

8.1 Urinalysis 

Each batch of specimens sent to the laboratory for 

analysis should be accompanied by at least two control 

urine specimens. When possible, these control specimens 

should be taken from individuals who are not and have not 

been occupationally exposed to uranium; otherwise simu

lated controls known to contain a uranium concentration 

less than I pg/L may be used. Aliquots of each of these 

control urine specimens should be taken; one should be a "blank," one should be spiked with uranium to obtain a 

concentration of 10 to 20 ,g/L, and one should be spiked 

to 40 to 60 pg/L, the actual spiked concentrations being 

recorded confidentially and not available to the analytical 

laboratory. When results are received, the licensee should ensure that each reading is corrected for the reading of the 

corresponding blank, that the net reading of each spiked 

sample is recorded, and that an average of the percent 

deviation of the spiked sample net reported values from the 

"true" amount of spiked uranium sample is calculated. The 

percent deviation for the spiked samples accompanying 

each batch of urine specimens should be within 30% of the 

spiked values. Otherwise, the most recent batch of affected 

samples should be rerun, and steps should be taken to 

correct the procedures for spiking or the procedures for 

laboratory analyses, or both. 

In order to provide adequate quality control within the 

analytical laboratory as well as to provide a check on the 

quality control program of the mill, the analytical labora

tory should duplicate the analysis of 10% to 20% of the 

samples received, including the blanks and spikes received 

from the mill. In addition, the laboratory should measure its own reagent and urine blanks and spiked standards as appropriate to. check its own procedures, provide its own calibration factors, check its LLDs, and evaluate its results 

for each batch. The laboratory should report the results of

its own blank and standard samples along with the other 

results reported to the mill. 

8.2 In Vivo 

For in vivo measurements, a quality control program 

using persons known to have no lung or systemic uranium 

burdens and phantoms spiked with known amounts of 

uranium should be used to test the counting system before 

measurements on each group of employees. 

9. USE OF RESPIRATORY PROTECTION DEVICES 

Licensees using respiratory protection devices in accor dance with paragraph 20.103(c) of 10 CFR Part 20 are to 

conduct bioassay programs in accordance with paragraph 

20.103(c)(2) and NUREG-0041, "Manual of Respiratory 

Protection Against Airborne Radioactive Materials" (Ref. 5). 

Under certain conditions, bioassay measurements should 

be performed to ensure the proper evaluation of personnel 

exposure and to evaluate the actual effectiveness provided 

by respiratory protection devices. If a worker wearing such 

a device is subjected for a period of I week to an average 

concentration greater than 10-10 pCi/mL (3.7 x 10-6 

Bq/mL), as given in Table 1, Column 1, of Appendix B 

to 10 CFR Part 20 for soluble natural uranium, urinalysis 

should be performed to test the actual effectiveness of the 

device. TI-s special bioassay measurement should also be 

performed if for any reason the magnitude of the exposure 

that would have occurred if no respiratory protection de

vice had been worn is unknown. The time that the sample 

for this special measurement was collected should be 

recorded; it should be consistent with the need to relate 

bioassay results to kidney exposure (see Section 6). 

The appropriate urinalysis or in vivo measurement given 

in Section 3 of this guide should not be reduced because of 

the use of respiratory protection devices. 

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, the 

method described in this guide will be used in the evalua

tion of existing bioassay programs of uranium mill licensees 

or proposed programs of applicants for such licenses.

1-1

8.22-4
Table 1

CORRECTIVE ACTIONS BASED ON MONTHLY URINARY URANIUM RESULTSa

Urinary Uranium 

Concentration 

Less than 15 pg/L 

15 to 35 pg/L 

Greater than 35 pg/L 

Confirmed to be greater 

than 35 .gL for txvo 

consecutive specimens., 

confirmed to be 

greater than 130 ug/L 

for an\ single specimen. 

or air sampling indica

tion of more than a 

quarterly limit of 

intake

Interpretation

Uranium confinement and air 

sampling programs are 

indicated to be adequate.b 

Uranium confinement and air 

sampling may not provide an 

adequate margin of safety~b 

Uranium confinement and 

perhaps air sampling programs 

are not acceptable.c 

Worker may have exceeded 

regulatory limit on intake.

Actions

None. Continue to review further bioassay results. 

1. Confirm results (repeat urinalysis). 

2. Identify the cause of elevated urinary uranium and initi

ate additional control measures if the result is confirmed. 

3. Examine air sampling data to determine the source and 

concentration of intake. If air sampling results are 

anomalous, investigate sampling procedures. Make correc

tions if necessary. 

4. Determine whether other workers could have been exposed 

and perform bioassay measurements for them. 

5. Consider work assignment limitations until the worker's 

urinarv uranium concentration falls below 15 ljg/L. 

6. Improve uranium confinement controls or respiratory 

protection program as investigation indicates. 

1. Take the actions given above. 

2. Continue operations only if it is virtually certain than no 

other worker will exceed a urinary uranium concentra

tion of 35 pg/L. 

3. Establish work restrictions for affected employees or 

increase uranium confinement controls if ore dust or 

high-temperature-dried yellowcake are involved. 

4. Analyze bioassay samples weekly. 

I. Take the actions given above. 

2. Have urine specimen tested for albuminuria. 

3. Obtain an in vivo count if worker may have been exposed 

to Class Y material or ore dust. 

4. Evaluate exposures. 

5. Establish further uraniun confinernent controls or 

respiratory protection requirements as indicated. 

6. Consider continued work restrictions on affected 

employees until urinary concentrations are below 15 pJg/L 

and laboratory tests for albuminuria are negative.

aUse Figures 1-3 to adjust action levels for other frequencies of bioassay sampling. The model used in NUREG-0874 (Ref. 1) employs 

fractional composition values (F , F 2 , F 3 ) for Class D, Class W, and Class Y components of yellowcake compounds. The assigned values 

in NUREG-0874 are based on dala from available literature. The use of alternative values of F 1 , FZ, and F specific for a particular opera

tion are acceptable provided (1) details regarding their determination are described and mentioned m employee exposure records (see para

graph 20.401(c)(1) of 10 CFR Part 20) and (2) the model as published in NUREG-0874 is then used in the determination of alternative 

urinalysis frequencies and action levels. 

bHowever, if a person is exposed to uranium ore dust or other material of Class W or Y alone, refer to Section 6 of NUREG-0874 

about the possibility of the need for conducting in vivo lung counts on selected personnel or about using alternative urine sampling times 

and associated action levels computed using NUREG-0874. 

c Unless the result was anticipated and caused by conditions already corrected.

8.2 2-5
Table 2

CORRECTIVE ACTIONS BASED ON IN VIVO RESULTSa 

Interpretation Actions

Below 9 nCi 

(330 Bq) 

9 to 16 nCi 

(330 to 590 Bq) 

More than 16 nCi 

(590 Bq)

May be below detection limit. 

This result does not necessarily 

indicate that uranium confine

ment and air sampling programs 

are validated. 

Confinement and air sampling. 

programs should be examined.b 

Uranium activity in lungs 

could be too high. 

Uranium confinement and air 

sampling probably are not 

acceptable.b 

Uranium activity in the lungs should 

be reduced by increased protection 

measures for the workers involved.

Rely on urinalysis results to determine corrective actions 

(unless air sampling indicates quarterly intake limits are 

exceeded for ore dust). 

1. Confirm result (repeat measurement within 6 months). 

Ensure that results are not caused by body surface 

activity. 

2. Examine air sampling data to determine source and 

concentrations of intake. If air sampling results are 

anomalous. investigate air sanplhtg procedures. Make 

corrections, if necessary. 

3. Identify the cause of elevated activity and initiate addi

tional uranium confinement control measures. 

4. Determine whether other \%orkers could have been 

exposed and perform special bioassay measurements for 

them. 

5. Consider work assignment linmiations that will permit the 

lung burden to be reduced through natural elimination; 

ensure that the lung burden does not exceed 16 nCi 

(590 Bq). 

1. Within 90 days, take the actions listed above for 9 to 

16 nCi (330 to 590 Bq). 

2. Establish work restrictions for affected workers or 

increased uranium confinement control measures. 

(Normally workers with a lung burden greater than 16 nCi 

(590 Bq) are not allowed by their employer to resume 

work in airborne activity areas until the burden is 

reduced to less than 9 nCi or 330 Bq.) 

3. Perform individual case studies (bioassays) for affected 

workers. 

4. Continue operations only when it is virtually certain no 

additional workers will exceed 16 nCi (590 Bq).

a The model used in NUREG-0874(Ref. 1) employs fractional composition values (F F F ) for Class D, Class W, and Class Y compo

nents of yellowcake compounds. The assigned values in NUREG-0874 are based on data from vai.Able literature. The use of alternative values of F , F and F specific for a particular operation are acceptable provided (1) details regarding their determination are described and ment~one3 in employee exposure records (see paragraph 20.401(c)(1) of 10 CFR Part 20) and (2) the model as published in NUREG-0874 is 

then used in the determination of alternative urinalysis frequencies and action levels. 

bUnless the result was anticipated and caused by conditions already corrected.

)

8.22-6

Amount of 

Uranium 

Detected
103

-- The contribution to urinary 

excretion from systemic pathways uJ 102 . Z - Total urinary excretion 

z 

z 3_______ 

S101 

L

0 % 

_z% 

z 

W 10_ 

z 

10

100 101 30 102 10o 104 

TIME AFTER EXPOSURE (Days) 

Figure 1 Uranium Concentration in Urine Following Single Exposure to High-Fired Yellowcake 

(Intake = 160,000 ,.g U = I ALl) (from NUREG-0874, Ref. 1)

8.22-7
LEGEND: 

... =.The contribution to urinary 

excretion from kidney pathways 

-m., The contribution to urinary 

excretion from systemic pathways 

- Total urinary excretion

101 30 102 10

TIME AFTER EXPOSURE (Days) 

Figure 2 Uranium Concentration in Urine Following Single Exposure to Low-Fired Yellowcake 

(Intake = 260,000 pg U = 1 ALl) (from NUREG-0874, Ref. 1)

I

8.22-8

-J 

0, 

z 

z 

z 

U. 

0 

z 

0 

4 

IU 

z 

0 

U

102 

101 

100

10"1 101L 

102

10r4
103

" The contribution to urinary 

-10, excretion from systemic pathways 

uj 

z - Total urinary excretion 

z 

1 6 

S101

0 ' 

c % 

z 10° 

I- LU \ 

10-1 , I , ,,, 

100 101 30 102 10, 104 

TIME AFTER EXPOSURE (Days) 

Figure 3 Uranium Concentration m Urine Following Exposure to Ore Dust (from NUREG-0874, Ref. 1)

8.22-9
REFERENCES

1. R. E. Alexander, R. B. Neel, J. S. Puskin, and A. Brod

sky, "Internal Dosimetry Model for Applications to 

Bioassay at Uranium Mills," NUREG-0874,* U.S. 

Nuclear Regulatory Commission, Washington, DC, 1986. 

2. International Commission on Radiological Protection, 

"Report of ICRF Committee II on Permissible Dose for 

Internal Radiation (1959), with Bibliography for Biolog

ical Mathematical and Physical Data," ICRP Publication 

2,** Pergamon Press, Elmsford, NY, 1960. 

3. P. E. Morrow et al., "Metabolic Fate and Evaluation of 

Injury in Rats and Dogs Following Exposure to the

Hydrolysis Products of Uranium Hexafluoride," 

NUREG/CR-2268,* U.S. Nuclear Regulatory Commis

sion, Washington, DC, 1982. 

4. American National Standards Institute (ANSI)/Health 

Physics Society (HPS), "Performance Criteria for Radio

bioassay," Draft ANSI/HPS-N13.30, 1987.*** 

5. J. L. Caplin, "Manual of Respiratory Protection Against 

Airborne Radioactive Materials," NUREG-0041,* U.S. 

Nuclear Regulatory Commission, Washington, DC, 1976.

BIBLIOGRAPHY

Alexander, R. E., "Applications of Bioassay for Uranium," 

WASH-1251,* U.S. Atomic Energy Commission, Washing

ton, DC, 1974. 

Atomic Energy Control Board,"Guide to Bioassay of Uranium 

at Uranium Mine-Mill Facilities," Regulatory Document R-5, 

1981. Available from the Atomic Energy Control Board, P.O. 

Box 1046, Ottawa, Ontario, Canada K1P 5S9. 

Fisher, D. R., et al. (Pacific Northwest Laboratory, Battelle 

Memorial Institute), "Measurements of 2 3 4 U, 2 3 8 U, and 

2 3 0 Th in Excreta of Uranium Mill Crushermen," 

NUREG/CR-2503,* U.S. Nuclear Regulatory Commission, 

Washington, DC, 1982. 

McGuire, S. A., "The NRC's Limit on Intake of Uranium 

Ore Dust," NUREG-0941,* U.S. Nuclear Regulatory 

Commission, Washington, DC, 1983. 

-Copies may be purchased from the Superintendent of Docu

ments, U.S. Government Printing Office, Post Office Box 37082, 

Washington, DC 20013-7082; or the National Technical Information 

Service, 5285 Port Royal Road, Springfield, VA 22161.

Spitz, H. B.. J. C. Simpson, and T. L. Aldridge (Pacific 

Northwest Laboratory, Battelle Memorial Institute), 

"Analysis of Uranium Urinalysis and In Vivo Measurement 

Results from Eleven Participating Uranium Mills," 

NUREG/CR-2955,* U.S. Nuclear Regulatory Commission, 

Washington, DC, 1984. 

Swaja, R. E., and C. S. Sims (Oak Ridge National Labora

tory), "Occupational Radiological Monitoring at Uranium 

Mills," NUREG/CR-3598,* U.S. Nuclear Regulatory 

Commission, Washington, DC, 1984. 

U.S. Nuclear Regulatory Commission, "Health Physics 

Surveys at Uranium Mills," Regulatory Guide 8.30,* 

Washington, DC, June 1983. 

**ICRP publications are available from Pergamon Press, Fairview 

Park, Elmsford, NY 10523. 

***Available from the Health Physics Society, 1340 Old Chain 

Bridge Road, Suite 300, McLean, VA 22101.

8.22-10
APPENDIX A

LOWER LIMIT OF DETECTION OF URANIUM

For the purposes of this guide, the lower limit of detec

tion (LLD) is defined as the smallest concentration of 

radioactive material in urine that has a 95% probability 

(chance) of being detected when measurement procedures 

are set so that the concentration level at which detection is 

considered significant produces only a 5% chance of calling 

a background reading a positive sample.* Radioactive 

material is then called "detected" when the value obtained 

from an instrument reading is above the LLD and is thus 

high enough to permit a conclusion that activity above the 

system background is determined to be present. Thus, for a 

fluorometric measurement that may include a radiochemi

cal separation in which the "blank" urines fluctuate with a 

standard deviation Sb. the LLD corresponds to an activity 

that is defined as: 

4.65Sb 

LLD - K t 

KEvYe'

Where 

LLD = the lower limit of detection (,g/L or uCi!L),

Sb the standard deviation of fluctuations in 

fluorometer blank measurements or count 

rate (counts per second) for a specific time 

of measurenient and spe.cifi aliquot \ olume, 

K conversion or calibration factor to convert 

units of S._ from instrument scale reading 

units to mass or activity units. units of K 

n-.ý b _A ._g or d sec- Ci if activity is 

counted to obtain the final result (this term 

is omitted Ai S. iP e.ven in microcuries 

u~recti by use of a calibration standard). 

L i. counuting ei1icilcAn kounis per disinte

gration i it is I ihen a fluorometric standard 

, measur:. in tne same geometr. as the 

sainplc. 

volume (in liters) of aliquot taken from the 

urine sample and added to the flux in the 

fusion dish. Note: As long as the concentra

tion of uranium in the aliqnot is the same as 

the concentration in the original urine sam

ple, the volume of the original urine sample 

does not affect this calculation. 

Y the fractional radiochemical yield or recov

ery (if applicable), 

""This Jefinilion of LI.D was chosen (. he consistent w.ith the 

NRC position previousl\ stniý, iir. i.hes I and 3 of Regulatory 

Guide 4.8, "'Fnvironmental Technijz! Specifications for Nuclear 

Poxýer Plants.- The definition is also used in other regulatory guides. 

among thetn 4.14. "Radiological Effluent and ILnvironmental 

Monitoring at Uranium Mills": 8.14, "Personnel Neutron Dosim

elers": and 8.30, "Healtl l'hysi.. Surveys in Uranium Mills."

= the decay constant for the particular radio

nuclide, and 

= the elapsed time between sample collection 

and counting for correcting for radioactive 

decay when decay during time t is signifi

cant, but decay is negligible during the 

fluorometric measurement. 

EXAMPLE: LLD FOR URANIUM WHEN FLUOROMET

RIC ANALYSIS IS USED 

This example is worked in terms of micrograms of nat

ural uranium per liter of urine. The LLD could just as well 

be calculated in terms of microcuries or becquerels of ura

nium per liter. A conversion factor of 6.77 x 10-7 lCi/.ig 

(0.025 Bq/1,g) for natural uranium can be used if the 

uramum quantity is known in micrograms. The quantity of 

iuranium added to the fusion dish will be determined, and 

then it will be divided by the volume of urine in the all

quot taken from the total collected sample. 

First. determine the standard deviation of the back

ground measurement (blank urine) (which will approxi

mate an estimate of the standard error of the average of a 

triplicate measurement if calculated as shown below). In 

this example, urine samples were taken from 12 individ

uals who worked in areas of the plant where no uranium 

exposure could have occurred. For each of these "blank" 

urines, three (triplicate) measurements were made: each 

measurement consisted of taking 0.2 mL from an individ

ual urine sample and pipetting it into a platinum dish con

taining a NaF pellet, which was then fused and placed into 

a fluorometer for measurement. The readings (in micro

amperes in this case) of the three 0.2 mL aliquots of each 

individual "blank" urine were then averaged. 

The 12 triplicate averages for the blank urines were:

Sample Number, i 

1 

2 

3 

4 

5

6 

7 

8 

9 

10 

I1 

12

Average Fluorometer 

Readings (X.) 

(microamperes)

0 

0.07 

0.07 

0.07 

0 

0 

0.13 

0.13 

0.17 

0.10 

0.13 

0

The standard deviation S (same as an estimate of the 

standard error of the triplic t

Ie average I may be calculated 

by the following equation (or a computer or calculator pro

grammed for this equation):

8.22-1I1
1 n Sb=ý E (Xi - X) 2 

i 

n = the number of samples 

Xi = the average reading for triplicate i from sample i 

X = the average of all triplicate averages 

For the data above, the standard deviation is: 

Sb= +0.0612 ijAandX=0.0725 11A 

Convert Sb to micrograms of uranium. On this fluorom

eter, samples of pure U 30 8 averaging 0.012 vig added to the 

fusion dish gave readings in the fluorometer averaging 3.44 

p.A. The fluorometer will thus have a calibration factor 

of 287 ýiA/pg U30 8 . The U3 0 8 compound is 85% uranium 

by weight (238 x 3 =714, 16 x 8 = 128, 714/842 = 0.85). 

Therefore, the fluorometer will read 338 WA/pig of elemen

tal uranium (287/0.85 = 338). 

Now, the standard deviation in micrograms of uranium is 

calculated: 

0.0612 LA 

Sb= 338 ,jA/.g =0.000181 Lig of uranium.

If this is converted to microcuries using the conversion 

factor given before, then 

Sb = 0.000181 pjgx 6.77 x 10-7 ICi/,g 

= 1.23 x 10-0 ijCi (4.55 x 10-6 Bq) 

In the equation for LLD, the counting efficiency will be 

1. (The term E is not applicable to a fluorometric analysis.) 

The aliquot volume of 0.2 mL is used in the LLD equation 

since the numerical value for each fluorescence reading is 

related to this volume of urine. Also, for a fluorometric 

reading compared against a calibration factor, the radio

chemical yield is not applicable, and Y should be set equal 

to 1. The exponential term for radioactive decay, exp(-)t), 

will also be equal to 1 since the half-life of uranium is so 

long that the amount of decay between collection and 

analysis will be negligible. Therefore, the LLDs in mass and 

activity concentration units become:

4.65 x 0.000181 

LLDm = 0.0002 = 4.21 pg/L

4.65 x 1.23 x 1001 

LLDa = 0.0002 

= 2.86 x 10-6 uCi/L L0.1 0 6 Bq)

-I

8.22-12
VALUE/IMPACT STATEMENT

A draft value/impact statement was published with 

Proposed Revision I to Regulatory Guide 8.22 (Task 

OP 013-4) when the draft revised guide was published for 

public comment in January 1987. No significant 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 copy

ing for a fee at the Commission's Public Document Room 

at 1717 H Street NW., Washington, DC, under Task OP 

013-4.

8.22-13
UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

WASHINGTON, D.C. 20555

OFFICIAL BUSINESS 

PENALTY FOR PRIVATE USE, $300

FIRST CLASS MAIL 

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