ML22279B040

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ROP Radiation Safety Brief October 2022, Selected Topics in Radiation Safety Oversight and Licensing
ML22279B040
Person / Time
Issue date: 10/06/2022
From: David Garmon-Candelaria
NRC/NRR/DRA/ARCB
To:
References
Download: ML22279B040 (50)
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Selected Topics in Radiation Safety Oversight and Licensing David Garmon, Health Physicist Radiation Protection and Consequence Branch Division of Risk Assessment Office of Nuclear Reactor Regulation October 6, 2022

Purpose

  • Describe how the U.S. NRC provides oversight of radiation safety at US NPP
  • Reactor Oversight Process
  • Inspection examples
  • Describe licensing functions as they relate to radiation safety
  • Review some aspects of radiation monitoring at US NPP
  • Types of radiation monitoring
  • Roles and responsibilities
  • Data 2

Topics of Interest

  • Establishing and conducting a radiation monitoring program
  • On-site and off-site radiation monitoring
  • Data management
  • NRC Licensing
  • Response to identified issues [inspection finding disposition]

3

=

Background===

4

5 NRR Letter dated October 15, 2019: https://www.nrc.gov/docs/ML1926/ML19260E683 NRC Values: https://www.nrc.gov/about-nrc/values.html

Key Day-to-Day Functions 6

Regulatory Hierarchy

  • Atomic Energy Act and Other Applicable Legislation
  • Plant-Specific Licensing Basis
  • Title 10 of the Code of Federal Regulations (CFR)
  • Operating License
  • Technical Specifications
  • Design Basis, Final Safety Analysis Report, Certain Commitments etc.

7

Oversight Framework The regulatory framework for reactor oversight is a risk-informed, tiered approach to ensuring plant safety. There are three key strategic performance areas: reactor safety, radiation safety, and safeguards. Within each strategic performance area are cornerstones that reflect the essential safety aspects of facility operation. Satisfactory licensee performance in the cornerstones provides reasonable assurance of safe facility operation and that the NRCs safety mission is being accomplished.

Within this framework, the NRCs operating reactor oversight process provides a means to collect information about licensee performance, assess the information for its safety significance, and provide for appropriate licensee and NRC response. Because there are many aspects of facility operation and maintenance, the NRC inspects utility programs and processes on a risk-informed sampling basis to obtain representative information.

8

9

Occupational Radiation Safety - NRC regulations set a limit on radiation doses received by plant workers, and this cornerstone monitors the effectiveness of the plant's program to control and minimize those doses.

Public Radiation Safety - This cornerstone measures the procedures and systems designed to minimize radioactive releases from a nuclear plant during normal operations and to keep those releases within federal limits.

Radiation Safety Cornerstones 10

11 Assessment of Performance

12 Communicating Significance Increasing Safety Significance Green White Yellow Red Performance Indicators / Inspection Findings Assessment of Performance - Action Matrix Columns Licensee

Response

Regulatory

Response

Degraded Performance Multiple/Repetitive Degraded Cornerstone Unacceptable Performance Increasing Safety Significance, Inspection, Management Involvement and Regulatory Action

Radiation Safety Cornerstones 13

Performance Indicators

  • Keep occupational dose to individual workers below the limits specified in 10 CFR Part 20 Subpart C and
  • Use, to the extent practical, procedures and engineering controls based upon sound radiation protection principles to achieve occupational doses that are ALARA per (20.1101(b))
  • To assess the performance of the radiological effluent control program

Reference:

RIS 2000-08, IMC 0308, NEI 99-02, Rev 7 14 https://www.nrc.gov/reactors/operating/oversight/pi-summary.html

Occupational Radiation Safety PI

  • Unintended exposure occurrences 15 Occupational Radiation Safety Performance Indicator Threshold: White Threshold: Yellow Threshold: Red Increased Regulatory Response Band Required Regulatory Response Band Unacceptable Performance Occupational Exposure Control Effectives

> 2

> 5 Not Applicable

Public Radiation Safety PI

  • Sum of release occurrences per reactor unit that exceed the following:
  • Liquid: 1.5 mrem/qtr (whole body) or 5 mrem/qtr (organ) or
  • Gaseous: 5 mrads/qtr (gamma) or 10 mrads/qtr (beta) or 7.5 mrem/qtr (organ dose from I-131, I-133, H-3 and particulates) 16 Public Radiation Safety Performance Indicator Threshold: White Threshold: Yellow Threshold: Red Increased Regulatory Response Band Required Regulatory Response Band Unacceptable Performance RETS/ODCM Effluents

> 1

> 3 Not Applicable

Inspections Types and Purpose

  • Types
  • Baseline inspections
  • Supplemental inspections
  • Generic safety issue, special and infrequent inspections
  • Objectives
  • To obtain factual information providing objective evidence that power reactor facilities are operated safely, and licensee activities do not pose an undue risk to public health and safety
  • To determine the causes of declining performance before such performance reaches a level that may result in undue risk to public health and safety
  • To identify those safety significant issues that may have generic applicability
  • Baseline: provide sufficient examination, along with PIs, that licensees are meeting the objectives of the ROP cornerstones 17

Inspection Areas 18 IP 71124 Radiation SafetyPublic and Occupational 12/21/17 17-031

.docx IP 71124.01 Radiological Hazard Assessment and Exposure Controls 12/29/21 21-041

.docx IP 71124.03 In-Plant Airborne Radioactivity Control and Mitigation 12/23/19 19-042

.docx IP 71124.04 Occupational Dose Assessment 12/23/19 19-042

.docx IP 71124.05 Radiation Monitoring Instrumentation 03/04/20 20-014

.docx IP 71124.06 Radioactive Gaseous and Liquid Effluent Treatment 03/04/20 20-014

.docx IP 71124.07 Radiological Environmental Monitoring Program 03/04/20 20-014

.docx IP 71124.08 Radioactive Solid Waste Processing and Radioactive Material Handling, Storage, and Transportation 03/04/20 20-014

.docx https://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html

Inspection Finding Process 19

20 Objective and Attributes - Occupational

21 Objective and Attributes - Public

22 Significance Determination

  • Objectives
  • Characterize safety significance of inspection findings using best available info.
  • Provide an objective common framework for communicating significance
  • Provide a basis for timely assessment and enforcement actions

Follow-On Activities 23

Example: Inspection Finding Resolution

  • Event
  • At a pressurized water reactor facility (PWR Unit 1), several workers were internally contaminated when a licensee failed to adequately evaluate the radiological hazards involved with the installation of steam generator nozzle dams.
  • This resulted in the failure to adequately identify the presence of alpha emitting isotopes in the SG bowls in concentrations which caused a substantial potential exposure to workers in excess of applicable regulatory requirements.

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Example: Inspection Finding Resolution

  • Issue of concern identified when the workers reported to other plants (several days after the nozzle dam job at PWR Unit 1) and discrete radioactive particles were identified on their boots and clothing
  • The NRC conducted a special inspection (reactive inspection) and identified deficiencies in the licensees hazard control, survey and monitoring performance
  • Focus on the monitoring issue for this example
  • Licensee did not take adequate air samples and bioassay in order to determine exposure to workers
  • Inspection finding
  • Need to determine significance

26 Finding Identified ALARA Planning or Work Controls?

Is 3 Year Rolling Average Collective Dose

>135 person-rem/unit: PWR Or >240 person-rem/

Unit for BWRs?

Actual Dose

> 25 person-rem?

Greater than 4 Occurrences?

White Yes Yes Yes Yes Green No No No

27 Was It An Overexposure?

SDE Exposure?

Was the Dose

> 5 Times the Limit?

Was SDE > 5 Times The Limit?

Red Yes Yes No Yes Yellow No No White Yes No

28 SDE/DRP Exposure?

Was There A Substantial Potential?

Was the Ability To Assess Dose Compromised?

No Yes Green No Green Yes Was It A Whole Body Exposure in a VHRA?

White Yellow No No Yes Yes

Substantial Potential

  • An event presents a substantial potential when it was fortuitous that the resulting exposure or release did not exceed the limits of 10 CFR Part
20. The concern is not the significance of the resulting or potential exposure, but whether the licensee provided adequate controls over the situation, as required, to prevent exceeding the Part 20 limits. No credit is given for luck. When considering whether the circumstances of a particular case meet the threshold for escalated enforcement action for this example, the staff should attempt to construct a reasonable scenario in which a minor alteration of circumstances would have resulted in a violation of the Part 20 limits.
  • Circumstances such as (a) timing, (b) source strength, (c) distance, and (d) shielding should be considered.

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Licensing 30

Licensing Insights

  • Through the licensing process, the U.S. NRC authorizes an applicant to conduct any or all of the following activities:
  • Construct, operate, and decommission commercial reactors and fuel cycle facilities.
  • Possess, use, process, export and import nuclear materials and waste, and handle certain aspects of their transportation.
  • Site, design, construct, operate, and close waste disposal sites.
  • To become licensed for any of these activities (or to amend, renew, or transfer an existing license), an entity or individual submits an application to the NRC.

The NRC staff reviews the submission, using standard review plans, to ensure that the applicant's assumptions are technically correct and that the proposed activities will not adversely affect the environment 31

Licensing Insights (contd)

  • Public process except for proprietary information
  • NRC approves the application (amends license, or provides authorization as applicable)
  • NRC does not advise or propose alternatives
  • Sometimes licensees supplement applications based on NRC questions
  • Typically done as a collaborative effort by the staff because different technical disciplines are involved
  • Project managers vs. Tech Staff
  • Examples of RP-related licensing actions
  • Request for authorization to use certain types of respiratory protection (or different protection factors)
  • Request for approval of changes to consensus standards referenced in the Technical Specifications (e.g., for worker qualifications)
  • Request to commence tritium production at a commercial nuclear power plant 32

Radiation Monitoring 33

General

  • Occupational
  • Personnel Monitoring
  • Surveying
  • Public
  • Effluent Monitoring
  • Environmental Monitoring 34

35 General Requirement to Survey

36 Monitoring Occupational Exposure

Occupational Monitoring/Survey Equipment 37

Effluents & Environmental Monitoring Laws 38

  • Atomic Energy Act (AEA) of 1954 (as amended)
  • Safe Drinking Water Act (SDWA) of 1974
  • Resource Conservation and Recovery Act (RCRA) of 1976
  • Department of Energy Organization Act of 1977
  • Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980
  • Nuclear Waste Policy Act of 1982
  • Energy Policy Act (EPAct) of 2005

Requirements and Key Guidance

  • Requirements: 20.1302, 50.36a, Technical Specifications
  • Key Guidance (1) RG 1.21, Measuring, Evaluating, and Reporting Radioactive Material in Liquid and Gaseous Effluents and Solid Waste, (2) RG 4.1, Programs for Monitoring Radioactivity in the Environs of Nuclear Power
Plants, (3) RG 4.15, Quality Assurance for Radiological Monitoring Programs (Inception Through Normal Operations to License Termination)Effluent Streams and the Environment, (4) RG 1.109, Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Demonstrating Compliance with 10 CFR Part 50, Appendix I, (5) NUREG-1301, Offsite Dose Calculation Manual Guidance: Standard Radiological Effluent Controls for Pressurized Water Reactors, and (6) NUREG-1302, Offsite Dose Calculation Manual Guidance: Standard Radiological Effluent Controls for Boiling Water Reactors.

39 https://www.nrc.gov/docs/ML2113/ML21139A224.pdf

Effluent and Environmental Reports 40 https://www.nrc.gov/reactors/operating/ops-experience/tritium/plant-info.html

Effluents - Types

  • 3 Types
  • Liquid
  • Gaseous noble gas
  • Gaseous other radionuclides (e.g., iodine)
  • We are also concerned with direct radiation but it is not formally considered an effluent in our guidance
  • Addressed in plant Technical Specifications
  • Must be monitored if the direct radiation from the plant is greater than background 41

Effluents - Where to Monitor

  • Significant Release Points
  • Location where radioactive material is released that contributes greater than 1% of the total activity discharged from all release points for a particular type of effluent (i.e., liquid, noble gas, other gas)
  • Assessments based on actual sample analysis results, radiation monitor responses, flow rate indications, tank level indications, and system pressure indications as necessary to ensure that the amount of radioactive material released, and the corresponding doses, are not substantially underestimated
  • Less-significant release points
  • Do not meet the criteria for significant but can possibly become significant
  • Assists in evaluation of abnormal releases/discharges 42

Effluents - What to Monitor

  • Principal Radionuclides Risk-Informed Approach
  • Contributes greater than 1 percent of the 10 CFR Part 50, Appendix I, design objective dose for all radionuclides in the type of effluent being considered
  • Contributes than 1 percent of the activity of all radionuclides in the type of effluent being considered
  • Some plants have reduced their effluents to the point that C-14 can become a principal radionuclide in gaseous effluents
  • Can be estimated by power history
  • Abnormal Releases and Abnormal Discharges
  • Releases - onsite, may impact decommissioning
  • Discharges - offsite, must be accounted for as contributor to public dose in a risk-informed manner 43

Effluent Monitoring Equipment 44 Particulate-Iodine-Noble Gas Monitor (Mirion)

Adjacent-to-Line Detector (General Atomics)

On-Line Process Monitor (Canberra)

Environmental Monitoring

1. Survey the radiological conditions in the vicinity of the facility before initial reactor operation to establish the baseline radiological conditions in the local environment.
2. Measure the levels of radiation and radioactive materials in the local environment during the lifetime of the facility.
3. Determine if any measurable levels of radiation or radioactive materials in the local environment are attributable to plant operation.
4. Determine if measurable levels of plant-related radiation and radioactive materials in the local environment are commensurate with the radioactive effluents and plant design objectives (e.g., as low as reasonably achievable).
5. Report measurement results, summaries, and trends regarding radiation and radioactive materials in the local environment.
6. Maintain the REMP by identifying changes in land use (e.g.,

agricultural land use in unrestricted areas) that may impact the measurements or measurement results associated with exposure pathways identified in the REMP.

45

Example - Direct Radiation Monitoring Program

  • Approximately 18,500 people live within 10 miles of the WBN site, with 80% of people living within 5-10 miles. Two small towns are located in this area:

Spring City (northwest of the site; pop. 2,200) and Decatur (south of the site; pop. 1,500). The area 10-50 miles from the site includes portions of the cities of Chattanooga (southwest of the site; pop. 170,000) and Knoxville (east by northeast of the site; pop.

185,000)

  • Radiation levels are measured by collecting samples within the vicinity of the plant, including air, water, food crops, soil, fish, and shoreline sediment, and by direct (i.e., external) monitoring.

46

Example - Direct Radiation Monitoring Program 47

  • The monitoring locations are grouped according to the distance from the plant.
  • The first group consists of all monitoring points within 2 miles of the plant (onsite)
  • The second group comprises all locations greater than 2 miles from the plant (offsite)
  • The average quarterly and annual gamma radiation levels determined from the dosimeters deployed around WBN in 2018 are summarized in Table 1
  • Level of knowledge
  • What information is it giving you (emergency response)
  • What function does it provide for the plant (indication, control of feature e.g., storm drain redirection, alarm)
  • Calibration
  • Calibration vs. Calibration check
  • Appropriate calibration source
  • Appropriate calibration geometry Some Issues with Radiation Monitors 48

Discussion david.garmon@nrc.gov 49

Key References 50

  • IMC 0305 - Operating Reactor Assessment Program: Overview of the assessment process/performance reviews, explanation of the Action Matrix
  • IMC 0612 - Issue Screening: Guidance for dispositioning of NRC findings, more-than-minor examples
  • IMC 2515 - Light Water Reactor Inspection Program Operations Phase
  • Federal Register Notices associated with key regulations
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