ML14161A666

DG-4019 (Proposed Revision 2 to Reg Guide 4.13) - Environmental Dosimetry - Performance Specifications, Testing, and Data Analysis (Preliminary)

ML14161A666
Person / Time
Issue date:	06/10/2014
From:	Steven Garry Office of Nuclear Regulatory Research
To:
Garry S
References
DG-4019 RG 04.013
Download: ML14161A666 (11)

Text

U.S. NUCLEAR REGULATORY COMMISSION June 2014 OFFICE OF NUCLEAR REGULATORY RESEARCH Revision 2 DRAFT REGULATORY GUIDE

Contact:

Steven Garry (301) 415-2766 This regulatory guide is being issued in draft form to involve the public in the early stages of the development of a regulatory position in this area. It has not received final staff review or approval and does not represent an official NRC final staff position. Public comments are being solicited on this draft guide and its associated regulatory analysis. Comments should be accompanied by appropriate supporting data. Written comments may be submitted through the federal government rulemaking Web site at http://www.regulations.gov. Alternatively, written comments may be submitted to the Rules, Announcements, and Directives Branch, Office of Administration, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001; or faxed to (301) 492-3446. Comments must be submitted by [insert date - 60 days from issuance].

Electronic copies of this draft regulatory guide, previous versions of this guide, and other recently issued guides are available through the NRCs public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/reg-guides/. The draft regulatory guide is also available through the NRCs Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html, under Accession No. MLXXXXXXXXX. The regulatory analysis may be found in ADAMS under Accession No. MLXXXXXXXXX.

DRAFT REGULATORY GUIDE DG-4019 1

(Proposed Revision of Regulatory Guide 4.13, Rev. 1, dated July 1977) 2 3

ENVIRONMENTAL DOSIMETRY - PERFORMANCE 4

SPECIFICATIONS, TESTING, AND DATA ANALYSIS 5

6 7

A. INTRODUCTION 8

9 Purpose 10 11 Environmental dosimetry methods such as Thermoluminescence dosimetry (TLD) and Optically 12 Stimulated Luminance dosimetry (OSL) are widely used to measure levels of X and gamma radiation for 13 environmental purposes at NRC-licensed nuclear facilities. This guide provides acceptable dosimeter 14 design specifications, methods of testing, dosimeter deployment, and data analysis. The data analysis 15 methods provide an acceptable method of determining the facility-related, direct radiation dose in the 16 general environment outside the nuclear facility suitable for demonstrating compliance with the 17 Environmental Protection Agency (EPA) 40 CFR 190, Environmental Radiation Protection Standards for 18 Nuclear Power Operations (Ref. 1).

19 20 Applicable Rules and Regulations 21 22 Title 10 of the Code of Federal Regulations (10 CFR), Part 20, (Ref. 2) Section 20.1301, Dose 23 limits for individual members of the public provides limits on the total effective dose 24 equivalent to individual members of the public from the licensed operation.

25 26 10 CFR 20.1302, Compliance with dose limits for individual members of the public requires 27 demonstration by measurement or calculation that the dose to members of the public does not 28 exceed the annual dose limits (including the dose limits of EPAs generally applicable 29 environmental radiation standards in 40 CFR 190). 10 CFR Part 20 Subpart F, Surveys and 30 Monitoring further requires that a licensee conduct surveys as may be necessary to comply 31 with the regulations of 10 CFR Part 20 including, when appropriate, the measurement of levels 32 of radiation.

33 34

2 10 CFR 20.1501(a), requires each licensee to make or cause to be made, surveys of areas, 35 including the subsurface, that may be necessary to comply with the regulations, and are 36 reasonable under the circumstances to evaluate the magnitude and extent of radiation levels, the 37 concentrations or quantities of residual radioactivity, and the potential radiological hazards of 38 the radiation levels and residual radioactivity detected.

39 40 10 CFR 20.1501(c) requires that instruments and equipment used for quantitative radiation 41 measurements (e.g., dose rate and effluent monitoring) are calibrated periodically for the 42 radiation measured.

43 44 10 CFR Part 50, (Ref. 3), Section 50.36 (a), Technical Specifications on Effluents from 45 Nuclear Power Reactors, which requires that licensees estimate the maximum potential annual 46 radiation doses to the public resulting from effluent releases.

47 48 10 CFR 50, Appendix I, Paragraph IV.B(2), "Numerical Guides for Design Objectives and 49 Limiting Conditions for Operation to Meet the Criterion 'As Low As Is Reasonably Achievable' 50 for Radioactive Material in Light-Water-Cooled Nuclear Power Reactor Effluents," requires 51 that licensees establish appropriate surveillance and monitoring programs to provide data on 52 measurable levels of radiation and radioactive materials in the environment.

53 54 10 CFR Part 50, Appendix A, "General Design Criteria for Nuclear Power Plants," Criterion 55 64, "Monitoring Radioactivity Releases," requires that nuclear power plant designs provide 56 means for monitoring the plant environs for radioactivity that may be released as the result of 57 normal operations, including anticipated operational occurrences, and as the result of postulated 58 accidents.

59 60 Related Rules and Regulations 61 62 10 CFR 20.2202, Notification of Incidents, requires each licensee to immediately report any 63 event involving byproduct, source, or special nuclear material possessed by the licensee that 64 may have caused or threatens to cause an individual to receive a dose meeting the limits of this 65 Section of the NRC regulations.

66 67 10 CFR 20.2203, Reports of Exposure, Radiation Levels, and Concentrations of Radioactive 68 Material Exceeding the Constraints or Limits, requires a report to be sent to the NRC 69 describing the reportable event.

70 71 10 CFR 20.2205, Reports to Individuals of Exceeding Dose Limits, requires when a licensee 72 is sending a report to the NRC of any exposure of an identified occupationally exposed 73 individual, or an identified number of the public, to radiation or radioactive material, the 74 licensee shall also provide the individual a report of the data included in the report to the NRC.

75 76 77 Related Guidance 78 79 ANSI N545-1975 Performance, Testing, and Procedural Specifications for 80 Thermoluminescence Dosimetry (Environmental Applications), Provides minimum acceptable 81 performance of TLDs used for environmental measurements. (Ref. 4) 82 83

3 ANSI/HPS N13.37-2014, Environmental Dosimetry, provides improved methods of 84 performance testing and establishes performance criteria and improved methods of analyzing 85 environmental data to determine potential radiological impacts of facility operations (Ref. 5).

86 87 Regulatory Guide 4.1, Radiological Environmental Monitoring for Nuclear Power Plants 88 (Ref. 6) 89 90 Regulatory Guide 1.21, Measuring, Evaluating, and Reporting Radioactive Material in Liquid 91 and Gaseous Effluents and Solid Waste (Ref. 7).

92 93 Purpose of Regulatory Guides 94 95 The NRC issues regulatory guides to describe to the public methods that the staff considers 96 acceptable for use in implementing specific parts of the agencys regulations, to explain techniques that the 97 staff uses in evaluating specific problems or postulated accidents, and to provide guidance to applicants.

98 Regulatory guides are not substitutes for regulations and compliance with them is not required.

99 100 Paper Reduction Act 101 102 This regulatory guide contains information collection requirements covered by 10 CFR Part 20 that 103 the Office of Management and Budget (OMB) approved under OMB control number 3150-0014. The NRC 104 may neither conduct nor sponsor, and a person is not required to respond to, an information collection 105 request or requirement unless the requesting document displays a currently valid OMB control number.

106 107 B. DISCUSSION 108 109 Reason for Revision 110 111 The 1977 (Revision 1) version of this Regulatory Guide (RG) endorsed (with exceptions) the 112 American National Standards (ANSI) N545 (1975) Performance, Testing, and Procedural Specifications 113 for Thermoluminescence Dosimetry (Environmental Applications). ANSI N545 has since been withdrawn 114 (removed from circulation) and superseded by the American National Standards Institute/Health Physics 115 Society (ANSI/HPS) N13.37 - 2014, Environmental Dosimetry.

116 117 Since the bases document for RG 4.13, Rev.1 has been replaced, the US NRC is revising RG 118 4.13. The RG 4.13, Rev. 2 (2014) is being issued to provide improved data analysis methods acceptable 119 for demonstrating compliance with regulatory requirements 10 CFR 20.1301(e); i.e., the Environmental 120 Protection Agency (EPA) 40 CFR 190, Environmental Radiation Protection Standards For Nuclear 121 Power Operations. This EPA standard establishes a dose limit of 25 mrem whole body, 75 mrem to the 122 thyroid, and 25 mrem to other organs for a real member of the public in the general environment (i.e., in 123 the unrestricted area).

124 125 126

Background

127 128 In 1975, the ANSI Committee N13 on Radiation Protection prepared the ANSI N545 standard 129 that specified minimum acceptable performance of TLDs used for environmental measurements; outlined 130 methods to test for compliance; and provided procedures for calibration, field application, and reporting.

131 ANSI N545 was subsequently approved and designated N545-1975 on August 20, 1975.

132 133

4 In ANSI N545, Appendix C, Interpretation of Field Exposures to Isolate Contributions 134 Attributable to Man-Made Radiation Sources (Such as a Nuclear Power Plant) guidance was provided on 135 acceptable methods of interpreting environmental monitoring results. In summary, the ANSI N545 136 guidance provided two methods of data analysis based on the premise that background dose rates were 137 either 1) invariant with location or 2) invariant with time, as follows:

138 139

1. Invariant with location: If background dose rates are assumed invariant from one 140 monitoring location to another, then dosimetry measurements could be made at control 141 stations (i.e., a field site remote from a nuclear facility) and compared to the measured 142 background (or changes in background) at indicator stations (i.e., field sites near the 143 facility).

144 145

2. Invariant with time: If background dose rate were invariant with time, then dosimetry 146 measurements could be made at each monitoring location and compared to prior 147 measurements at the same location.

148 149 Note: The ANSI N545 recognized that neither assumption was strictly valid; however, ANSI 150 N13.37 provides improved data analysis methods for background dose rates invariant with time. This 151 method compares current dosimetry measurements at each monitoring station with previous measurements 152 at the same location.

153 154 The ANSI/HPS N13.37 (2014) complements and extends the technical requirements and guidance 155 in International Standard IEC 62387, Radiation protection instrumentation - Passive integrating dosimetry 156 systems for personal and environmental monitoring of photon and beta radiation (Ref. 8). While the 157 performance criteria are generally comparable, by focusing specifically on passive environmental 158 monitoring dosimetry systems, the N13.37 testing approach may be seen as simplified from that in IEC 159 62387. Additionally, this standard extends beyond IEC 62387 by providing requirements and guidance for 160 deployment and data analysis of environmental monitoring dosimetry systems.

161 162 163 Harmonization with International Standards 164 165 The NRC has a goal of harmonizing its guidance with international standards, to the extent 166 practical. The International Commission on Radiological Protection (ICRP) and the International Atomic 167 Energy Agency (IAEA) have issued a significant number of technical guidance documents, and 168 recommendations addressing good practices in most aspects of radiation protection. Such documents 169 include:

170 171 The International Standard IEC 62387, Radiation protection instrumentation - Passive 172 integrating dosimetry systems for personal and environmental monitoring of photon and beta 173 radiation, IEC/CEI 62387-1:2007, March, 2012.

174 175 The NRC encourages licensees to consult this international document and implement the good 176 practices that are consistent with NRC regulations. It should be noted, however, that some of the 177 recommendations issued by these international organizations do not correspond to the requirements 178 specified in the NRCs regulations. In such cases, the NRCs requirements take precedence.

179 180 Documents Discussed in Staff Regulatory Guidance 181 182 Although this regulatory guide utilizes information, in part, from one or more reports developed by 183 external organizations and other third party guidance documents, the regulatory guide does not endorse 184

5 these references other than as specified in this regulatory guide. These reports and third party guidance 185 documents may contain references to other reports or third party guidance documents (secondary 186 references). If a secondary reference has itself been incorporated by reference into NRC regulations as a 187 requirement, then licensees and applicants must comply with that requirement in the regulation. If the 188 secondary reference has been endorsed in a regulatory guide as an acceptable approach for meeting an NRC 189 requirement, then the reference constitutes a method acceptable to the NRC staff for meeting that regulatory 190 requirement as described in the specific regulatory guide. If the secondary reference has neither been 191 incorporated by reference into NRC regulations nor endorsed in a regulatory guide, then the secondary 192 reference is neither a legally-binding requirement nor a generic NRC approval as an acceptable approach 193 for meeting an NRC requirement. However, licensees and applicants may consider and use the information 194 in the secondary reference, if appropriately justified and consistent with current regulatory practice, 195 consistent with applicable NRC requirements such as 10 CFR Part 20.

196 197 C. STAFF REGULATORY GUIDANCE 198 199

1. Quantitative Measurements 200 201 Environmental dosimetry programs should provide accurate quantitative radiation measurements 202 and analyses that are capable of demonstrating compliance with regulations 10 CFR 20.1301 and EPA 40 203 CFR 190. In order to do this, dosimetry systems should:

204 205 Meet environmental type testing criteria for system design 206 207 Meet radiological type testing for accuracy, precision, and linearity criteria 208 209 Be capable of measuring a quarterly dose of 20 mrem with a coefficient of variation not to 210 exceed ~7%

211 212 Be capable of determining a facility-related dose of ~ 5 mrem per quarter or ~ 10 mrem per 213 year 214 215

2. Regulatory Guide 4.13, Rev. 1 (1977) 216 217 RG 4.13, Rev. 1 (1977) continues to provide methods acceptable to NRC to demonstrate 218 compliance with the public dose limits of 10 CFR 20.1301. This 1977 version established the NRC position 219 that the ANSI N545-1975 standard is generally acceptable as a basis for using environmental dosimetry for 220 measurement of direct radiation in the environs, subject to the stated additional provisions and 221 qualifications listed in the Regulatory Guide 4.13, Revision 1.

222 223 Environmental dosimetry systems in current use that have been demonstrated to meet the 224 Regulatory Guide 4.13, Revision 1 criteria do not need to be retested to the radiation and environmental 225 type tests of ANSI/HPS N13.37-2014. However, licensees should have documentation that the 226 environmental dosimetry system has been tested and meets the criteria of RG 4.13, Revision 1 (or 227 equivalent), and provide adequate methods of data analysis to identify facility-related dose.

228 229

3. ANSI/HPS N13.37 (2014) 230 231 ANSI/HPS 13.37 (2014) provides improved acceptance criteria and data analysis methods for 232 analysis of direct radiation in the environs of NRC-licensed facilities. This Regulatory Guide endorses the 233

6 ANSI/HPS N13.37 standard as providing acceptable methods of performance testing environmental 234 dosimetry and analyzing environmental monitoring data.

235 236 237

4. Data Analysis Techniques provided in ANSI N13.37 238 239 An analysis of environmental dosimetry measurements must be analyzed using acceptable scientific 240 techniques. Data should be analyzed for each monitoring period (in lieu of annual review) so that 241 corrective actions can be taken promptly.

242 243 The first step in this method is to identify obvious data outliers and investigate apparent 244 discrepancies. This data should be analyzed before data corrections/adjustments (e.g., subtraction of 245 extraneous dose) (see definitions in Appendix A) or data normalizations occur (e.g., adjusting data to a 246 normalized, 91 day monitoring period).

247 248 Acceptable analysis methods include analyzing results for each monitored location independently 249 from the other locations:

250 251

a. Evaluate Element Readings 252

i. Obtain element readings (from the field dosimeters, dosimeters at a control station, 253 and control dosimeters stored in lead shield). Note the distinction in terminology 254 between dosimeters at a control station (remote from the facility) and control 255 dosimeters stored in a lead shield.

256 ii. Identify characteristics of each elements filtration and /or phosphor (so that 257 element reading outliers can be properly determined).

258 iii. Perform a qualitative review of the element readings, and identify and investigate 259 any obvious outliers and make notations as to the circumstances 260 iv. Calculate1 the standard deviation (SD) and the coefficient of variation (CV) of the 261 remaining (credible and valid) element readings (i.e., after outliers have been 262 removed from the data set) 263

v. Review SD and CV data (i.e., for those elements expected to measure the same 264 dose quantity based on the same filtration or same phosphor). Identify and 265 document the reason for CVs greater than 10%.

266 vi. Calculate the valid (after removal of outliers) gross field dosimeter readings (i.e.,

267 the field dose plus the extraneous dose) for each monitored location. Note: Data 268 from dosimeters located at control stations is not particularly relevant in an analysis 269 method that is invariant with time, but the dosimeter readings at control stations 270 should be evaluated anyway and reported for consistency.

271 vii. Calculate the valid control dosimeter doses (i.e., after removal of outliers based on 272 control dosimeters stored in a lead shield) 273 274

b. Determine The Extraneous2 Dose 275 276 1 The SD and the CV of a small data set are not accurate measures of performance, but do provide an initial indication of performance.

2 Extraneous dose (e.g., storage dose, transit dose) has been the least understood process over the history of these measurements.

ANSI/HPS N13.37 provides details on proper methods of determining extraneous dose. Onsite processors can minimize extraneous dose by performing the processing very soon before deployment and after collection.

7

i. Determine the mean (average) dose on control dosimeters stored in a lead shield.

277 ii. Calculate the extraneous dose (the dose that the field dosimeters accrued while not 278 deployed in the field). Note: The mean control dosimeter dose is not an adequate 279 measure of the extraneous dose. See ANSI N13.37 methods of determining 280 extraneous dose.

281 282

c. Determine Field Doses 283 284

i. Determine the accrued field dose at each monitored location by subtracting the 285 extraneous dose. Note: A simple subtraction of the control dosimeter readings 286 from the field dosimeter readings is not an accurate method of assessing field dose.

287 ii. Normalize the data to a standard 91-day quarter (or other normalized period).

288 iii. Perform a qualitative comparison of the normalized, quarterly field doses to the 289 base-line background dose rate for each monitored location.

290 iv. Identify apparent outliers and investigate anomalies.

291

v. Remove substantiated outliers from the data set and document justifications.

292 293

d. Determine the dosimetry systems quarterly and annual minimum detectable dose (MDD).

294 Note: The MDD accounts for 3 standard deviations in measurements.

295 296

e. Determine the base-line background dose rate (at each monitored location).

297 298

f. Determine Quarterly Facility-Related Doses (at each monitored location) 299 300

i. Sum the quarterly MDD and the quarterly baseline background dose rate.

301 ii. Subtract the sum from the normalized field dose (to determine the facility-related 302 dose).

303 iii. Identify any detectable facility-related dose (e.g., exceeding 5 mrem during the 304 quarterly period).

305 iv. Investigate any detectable facility-related dose, and document substantiated 306 facility-related dose, and remove (with justification) any unsubstantiated doses 307 from the data set.

308 309

g. Determine the annual Facility-related Dose at each monitored location.

310

i. Sum the annual MDD3 and the annual baseline background dose rate.

311 ii. Subtract the sum from the normalized annual field dose to determine the annual 312 facility-related dose.

313 iii. Identify any detectable facility-related dose (e.g., exceeding ~10 mrem during the 314 annual period).

315 316

5. Quality Assurance 317 318 The quality assurance methods described in ANSI/HPS N13.37 are suitable methods of performing 319 quality assurance. In summary, there should be:

320 321 End-user quality assurance checks/measures 322 3 The annual MDD is less than the sum of the quarterly MDDs since the statistics are better.

8 Annual audits of the end-user by independent assessors 323 Annual blind spike testing 324 Triennial audits of the processor 325 326 Note: a processor laboratory accreditation program may be needed if the results of the quality 327 assurance program routinely identify unsatisfactory results.

328 329

6. Data Reporting 330 331 Report environmental data and analyses in accordance with Technical Specifications (e.g., in 332 accordance with the Offsite Dose Calculation Manual).

333 334 D. IMPLEMENTATION 335 336 The purpose of this section is to provide information to applicants and licensees regarding the 337 NRCs plans for using this regulatory guide.

338 339 Methods or solutions that differ from those described in this regulatory guide may be deemed 340 acceptable if they provide sufficient basis and information for the NRC staff to verify that the proposed 341 alternative demonstrates compliance with the appropriate NRC regulations. Current licensees may continue 342 to use guidance the NRC found acceptable for complying with the identified regulations as long as their 343 current licensing basis remains unchanged. Backfit and issue finality considerations do not apply to 344 licensees and applicants under 10 CFR Part 20.

345 346 REFERENCES 347 348

1. Environmental Protection Agency (EPA) 40 CFR 190, Environmental Radiation Protection 349 Standards for Nuclear Power Operations. 4 350 351

2. Title 10 of the Code of Federal Regulations (10 CFR), Part 20, Standards for Protection against 352 Radiation, U.S. Nuclear Regulatory Commission, Washington, DC 20555.5 353 354

3. 10 CFR Part 50, General Design Criterion 64, "Monitoring Radioactivity Releases," of Appendix A, 355 "General Design Criteria for Nuclear Power Plants."

356 357

4. American National Standards Institute (ANSI) N545 (1975) Performance, Testing, and Procedural 358 Specifications for Thermoluminescence Dosimetry (Environmental Applications). 6 359 4

Copies of EPA Library Services may be obtained through their Web site:

http://www.epa.gov/libraries/library_services.html.

5 Publicly available NRC-published documents are available electronically through the NRC Library on the NRCs public Web site at http://www.nrc.gov/reading-rm/doc-collections/. The documents can also be viewed online or printed for a fee in the NRCs Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD; the mailing address is USNRC PDR, Washington, DC 20555; telephone 301-415-4737 or (800) 397-4209; fax (301) 415-3548; and e-mail pdr.resource@nrc.gov.

6 Copies of American National Standards Institute (ANSI) documents may be purchased through their Web site at:

http://webstore.ansi.org/.

9 360

5. American National Standards Institute/Health Physics Society (ANSI/HPS) N13.37 - 2014, 361 Environmental Dosimetry - Criteria for System Design and Implementation. 7 362 363

6. Regulatory Guide 4.1, Radiological Environmental Monitoring for Nuclear Power Plants.

364 365

7. Regulatory Guide 1.21, Measuring, Evaluating, and Reporting Radioactive Material in Liquid and 366 Gaseous Effluents and Solid Waste.

367 368

8. International Standard IEC 62387, Radiation Protection Instrumentation - Passive integrating 369 dosimetry systems for personal and environmental monitoring of photon and beta radiation.

370 371 372 373 Appendix A 374 375 Plain Language Definitions (see also ANSI/HPS 13.37) 376 377 Accuracy: A measure of the difference between the measured value and the conventionally true value 378 (expressed either as the standard deviation or as the coefficient of variation (also referred to as the bias)).

379 380 Coefficient of Variation (CV): The standard deviation (of a series of measurements) divided by the mean 381 value of the measurements.

382 383 Baseline background dose (BQ or BA): The average background radiation dose based on historical 384 averages.

385 386 Bias: The mean deviation from the conventionally true value (expressed as a fraction of the 387 conventionally true value).

388 389 Conventionally true value (D): The best estimate of the delivered radiation dose.

390 391 Extraneous dose: The extra dose accumulated on a dosimeter prior to and after field deployment.

392 393 Facility-related dose (FQ or FA): The dose from radiation originating from the monitored facility.

394 395 Mean: The arithmetic average.

396 397 Minimum differential dose (MDDx): The smallest amount of facility-related dose that can be reliably 398 detected.

399 400 Performance Quotient (P): A measure of the accuracy in spiked dosimeter testing. The P value is 401 calculated as the spiked dosimeter reading. minus its spiked dose, divided by its spiked dose. The average 402 P value should not exceed 0.15 for the set of spiked dosimeters.

403 404 7

Copies of American National Standards Institute /Health Physics Society (ANSI/HPS) documents may be purchased through their Web site at: http://webstore.ansi.org/ or through HPS Web site at http://www.hps.org.

10 Precision: The variation of measured values around its mean measured value (expressed quantitatively as 405 either the standard deviation or as the coefficient of variation).

406 407 Standard deviation Sx: The average variation in a series of measurements, calculated as:

408 409

410

411 412 and 413 414 415 416 417 Transit dose: The dose received by a field dosimeter when not deployed in the field. This occurs from the 418 time of annealing to the time the dosimeter is deployed in the field, and from the time the dosimeter is 419 removed from the field to the time the dosimeter is processed. Transit dose does not include storage dose 420 during field deployment.

421