Regulatory Guide 8.22
| ML003739586 | |
| Person / Time | |
|---|---|
| Issue date: | 08/31/1988 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| References | |
| RG-8.22 Revision 1 | |
| Download: ML003739586 (14) | |
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 applicant
s. 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 tion 2 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 1 3 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 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> 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 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 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 L0
%
_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 L
101
102
10r4
10
3
"
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,"
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,"
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,"
U.S.
Nuclear Regulatory Commission, Washington, DC, 1984.
U.S.
Nuclear Regulatory Commission, "Health Physics Surveys at Uranium Mills,"
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 unit
s. 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 tIe 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
POSTAGE & FEES PAID
PERMIT No. G-67