LLW Performance Assessment & Safety Casefor Licensing US RW Management Facilities

Rateb (Boby) Abu Eid, Ph. D. (boby.abu-eid@nrc.gov)

Senior Advisor

Division of Decommissioning, Uranium Recovery, and Waste Management

Office of Nuclear Materials Safety and Safegurds

U.S. Nuclear Regulatory Commission,Washington D.C., 20555, USA

IAEA Technical Meeting CRAFT Part II

September 30, 2015

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Radioactive Waste Categories in the US

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10 CFR Part 61 Subpart C Performance Objectives

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LLW Timeframe and Performance Period

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NUREG-1573

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The Concept of IAEA Safety Case (SC)• NEA SC Definition: “The synthesis of evidence, analyses and

arguments that quantify and substantiate a claim that the repository (i.e.; disposal facility) will be safe after closure and beyond the time when active control of the facility can be relied on”.

• IAEA SC Definition: A collection of arguments and evidence to demonstrate the safety of a facility and to assist in key decision-making.

• The SC has to be developed in the early phases of the development of a project. It constitutes the basis for internal decisions by the operator/licensee (e.g.; site selection, safety evaluation, design conceptualization and optimization, etc.…) as well as to establish a dialogue with the regulator and stakeholders.

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IAEA Safety Case Components

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Stak

ehol

der a

nd R

egul

ator

y In

volv

emen

tSt

akeh

olde

r and

Reg

ulat

ory

Invo

lvem

ent Application of M

anagement System

Application of Managem

ent System

C. System DescriptionC. System Description

D. Safety AssessmentD. Safety Assessment

G. Limits, Controls and ConditionsG. Limits, Controls and Conditions

H. Integration of Safety ArgumentsH. Integration of Safety Arguments

E. It

erati

on a

nd D

esig

n O

ptim

izati

onE.

Iter

ation

and

Des

ign

Opti

miz

ation F. M

anagement of U

ncertaintyF. M

anagement of U

ncertaintyA. Safety Case ContextA. Safety Case Context B. Safety StrategyB. Safety Strategy

Safety Case & Decision Steps

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Need for Action

Disposal Concept

Site Selection & Design

Construction

Operation

Active Institutional Control

DisposalConcept

SiteSelection

andDesign

Construction

OperationClosure and

Active InstitutionalControl

PassiveInstitutional

Control

Waste Manager Operator

Need for Action

Operator

Regulator

Government

License Termination?

Role and Responsibility

Time Line

Public involvement throughout the process is encouraged

NRC’s Approach to Risk-Informed, Performance Based Assessments for

LLW & Decommissioning • Facilitate application of risk-informed and performance-based

implementation of the NRC’s rulemaking, licensing, and oversight functions for LLW, including waste incidental to reprocessing, and decommissioning on a case-by-case basis.

• Staff engagement in development, maintenance, and evaluation of probabilistic environmental models and codes for risk/dose analysis.

• Use of probabilistic distributions as inputs to uncertain physical and behavior parameters, particularly in independent staff reviews.

• In review of DOE waste incidental to processing determination, the staff utilizes risk-informed performance-based approaches including uncertainty/sensitivity analyses and alternate conceptual models. The risk insights gained during the review are utilized to establish the monitoring areas for a site

• Use of probabilistic tools with sensitivity/uncertainty analysis to demonstrate compliance with the dose criteria

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NRC’s Integrated Risk Management

ObjectiveManage the risks from the use of byproduct, source, and special nuclear

materials through appropriate performance-based regulatory controls and

oversight

GoalProvide risk-informed and performance-based defense-in-depth protection

to:

• Ensure appropriate barriers, controls, and personnel to prevent, contain, and mitigate exposure to radioactive material according to the hazard present, the relevant scenarios, and the associated uncertainties

• Ensure that the risk resulting from the failure of some or all of the established barriers and controls, including human errors, are maintained acceptably low

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Identify issues

Identify Options

Analyze

DeliberateImplement Decision

Monitor

DeliberationProcess

Decision-Making Process

Use a disciplined

process to achieve the risk management goal

A LLW Disposal Design Concept

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Cap

Waste

Inhalation of dust

Direct radiation from dust cloud

Direct radiation from waste volume

Intruder Construction

Intruder Scenario Used for LLW PA

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Cap

Waste

Inhalation of dust

Direct radiation from dust cloud

Direct radiation from waste volume

Deposition of dust

Soil to root transfer

Plant-to-animal-to-human

Plant-to-animal product-to-human

NOTE: Includes modified food pathways to account for non-equilibrium deposition and subsequent root uptake: (i) plant-human; (ii) plant-animal-human; and (iii) plant-animal product-human

Intruder Agriculture Scenario for LLW PA

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Scenarios and Pathways Used for 10 CFR Part 61

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RadionuclideRadionuclide ConcentrationConcentration

C-14C-14 296,000 MBq/m296,000 MBq/m33

C-14 in activated metalC-14 in activated metal 2,960,00 MBq/m2,960,00 MBq/m33

Ni-59 in activated metalNi-59 in activated metal 8,140,000 MBq/m8,140,000 MBq/m33

Nb-94 in activated metalNb-94 in activated metal 7400 MBq/m7400 MBq/m33

Tc-99Tc-99 111,000 MBq/m111,000 MBq/m33

I-129I-129 29.6 MBq/m29.6 MBq/m33

Alpha emitting transuranics Alpha emitting transuranics with ½ lives > 5 yearswith ½ lives > 5 years

3700 Bq/gram3700 Bq/gram

Pu-241Pu-241 129,500 Bq/gram129,500 Bq/gram

Cm-242Cm-242 740,000 Bq/gram740,000 Bq/gram

NRC Waste Classification Table for Long-Lived Radionuclides

Note: If concentration is < .1 Table value, waste is Class A. If concentrationis > 0.1 but less than or equal to Table value, waste is Class C. If concentration is > Table value, waste is greater than class C.

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NRC Waste Classification Table for Short-Lived Radionuclides

RadionuclideRadionuclide

Concentration, MBq/mConcentration, MBq/m33

Col. 1Col. 1 Col. 2Col. 2 Col. 3Col. 3

Total of all radionuclides with < 5 yr half-Total of all radionuclides with < 5 yr half-lifelife

25.9 X 1025.9 X 1066 n/an/a n/an/a

H-3H-3 1.48 X 1.48 X 661010 n/an/a n/an/a

Co-60Co-60 25.9 X 1025.9 X 1066 n/an/a n/an/a

Ni-63Ni-63 129,500129,500 2.59 X 102.59 X 1066 25.9X1025.9X1066

Ni-63 in activated metalNi-63 in activated metal 1.30 X 101.30 X 1066 25.9X1025.9X1066 259X10259X1066

Sr-90Sr-90 14801480 5.55X105.55X1066 259X10259X1066

Cs-137Cs-137 37,00037,000 1.63X101.63X1066 170X10170X1066

Note: If concentration does not exceed column 1, waste is Class A. If concentrationis > col. 1 and < col. 2, waste is Class B. If concentration is > col. 2 and < col. 3, waste is Class C. If > col. 3, waste is not acceptable for near-surface disposal

Comparison of NRC’s vs. IAEA RW Management Systems

International Atomic Energy Agency Waste

Categories

US Waste Categories

High Level Waste High Level Waste

Intermediate Level Waste

Greater-than-Class C LLW

Low Level Waste (LLW)

Class A, Class B and C LLW

Very Low Level Waste

Class A

Very Short Lived Waste

Material held for decay storage

Exempt Waste

Liquids/Air: Effluent releases

Solids: Case-by-case analysis

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LLW Classification Scheme & Disposal Sites

• Principal basis in deriving waste classification limits was protection of the inadvertent intruder.

• Secondary bases: Long-term environmental concerns Disposal facility stability Institutional control costs Financial impacts to small entities

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Steps in NRC NUREG-1573 PA Methodology Reviews

•Data evaluation•Conceptual models & scenarios•Parameter distributions•Mathematical models & codes•Consequence modeling & analysis •Sensitivity & uncertainty analysis• Initial evaluation of site performance• R-evaluation of data & assumptions• Assessment of compliance with 10 CFR 61.41 & §61.42

Specific Processes Considered in NRC LLW PA

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• Infiltration• UZ Flow• Eng. Barrier Performance

• Container Breach• Waste Form Leach• Source term releases

• VZ Transport• SZ flow and Transport• Surface water transport• Exposure scenarios & pathways transport• Dose to human

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Example of a Performance Assessment Process

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Schematic Illustration of Examples of Exposure Scenarios for DU Disposal

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GoldSim DU Disposal Model

PA Approach: Representation of LLW System, Conceptual & Mathematical Models, and Estimated Performance

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An Approach to Uncertainty Analysis

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Dose - Time PA Outputs

DOSE

TIME

Common Models/Codes Used In Reviews of Dose Assessments

• Decommissioning & EIS Analysis– RESRAD Codes (RESRAD Onsite 6.5; RESRAD-Build 3.5; and

RESRAD-Offsite (Beta Version 3.0)– D&D Screening Code (2.1 Updated Version)– FRAMES & GENII

• LLW & WIR– GoldSim– RESRAD 6.5 and RESRAD-OFFSITE– FRAMES and GENII– AMBER

• UR

– MILDOS-AREA

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PA & Integrated Risk Regulatory Issues

• How to treat future site conditions, processes, events, and climate change

• Exposure scenarios and compliance dose criteria• Performance of engineered barriers • Timeframe for LLW performance assessment • Treatment of sensitivity and uncertainty• Role of performance assessment during operational and post-

closure periods • Overall integration of site characterization, facility design

performance assessment, and safety analysis• Bench-marking and QA/QC issues• Stakeholders inputs

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• Disposal of the PGE Trojan Reactor Vessel Package at the US Ecology Low-Level Waste Disposal Facility near Richland, WA in August 1999 was the culmination of a unique combination of circumstances as well as hard work and dedication of hundreds of people in federal and state government and the private sector.

• The ability to classify the waste as Class C based on concentration averaging guidance, the availability of a in-compact disposal facility, and the accessibility to water conveyance resulted in a unique first of a kind disposal opportunity.

• Meticulous planning and implementation by licensees and their contractors coupled with scrupulous oversight by state and federal regulators led to successful, uneventful project completion.

• Predisposal Planning & Management of Radioactive Waste is the Key.

Trojan Reactor VesselAn Example of Predisposal Management

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Transporter, cradle, and RVP

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• Media Management - National media attention while barging up river - Managed by USE media consultant - Local media afforded work observation opportunity

• “Decontrolling” for the Show - Avoid bringing dignitaries into a controlled area - Eliminate need for visitor orientation

• Public Event on August 19, 1999 featuring Congressman Hastings

Public Affairs Component

Predisposal Management Cost/Time/Technology

• The first large commercial reactor vessel to be segmented for disposal was in 2008.

• In 2015 Energy Solutions completed the first segmentation of this type using an oxy-propane torch connected to a robotic fixture outside the vessel, a large-scale application of thermal cutting technology.

• The vessel came from the Zion nuclear power plant.

• The new procedure took only one month, significantly shorter than the seven months it took in the 2008 segmentation process

using abrasive water jet technology.

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Rulemaking for LLW Site Specific Analysis – Update of 10 CFR Part 61

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Staff New Guidance on Technical Analysis for Part 61 Site-Specific Analysis

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Technical Assessment

Stakeholders Involvement Public Meetings and Workshop

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The EIS Process & Public Involvement

• An environmental impact statement (EIS), under United States environmental law, is a document required by the National Environmental Policy Act (NEPA) for certain actions "significantly affecting the quality of the human environment".

• The purpose of the NEPA is to promote informed decision-making by federal agencies by making "detailed information concerning significant environmental impacts" available to both agency leaders and the public. It involves a great deal of stakeholders participation in the decision-making.

• An EIS is a tool for decision making. It describes the positive and negative environmental effects of a proposed action, and it usually also lists one or more alternative actions that may be chosen instead of the action described in the EIS.

• The EIS document is considered a segment of the safety case.

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Federal Regulations

Implementation Process

State Regulations

Politics Public

Expectations Competing

Standards

Regulatory Flexibility

What about risk

management?Safety Case

Disclaimer

This presentation was prepared as an account of work sponsored by an agency of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party’s use, or the results of such use, of any information, apparatus, product, or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. The views expressed in this presentation are not necessarily those of the

U.S. Nuclear Regulatory Commission.

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