International Atomic Energy Agency

Safety Requirements for
Disposal of Radioactive Waste
Phil Metcalf

NUCLEAR SAFETY RESEARCH FORUM 2010
"Perspectives of Safety Regulations and Research for Radioactive Waste Disposal"
February 23, 2010
Toyo University, Tokyo, Japan1

Safety Standards - Disposal

Waste
Disposal

DS 354

Near Surface
DisposalGeological
DisposalManagement
Mining and ofNorm
Processing
Residues

DS 356

DS 334

DS 352
Safety Case &Assessment
for Disposal

DS 355
Monitoring andSurveillance

DS 357
2

International Atomic Energy Agency

1. INTRODUCTION

2. PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT3. THE SAFETY REQUIREMENTS FOR THE DISPOSAL OF RADIOACTIVE WASTEREQUIREMENTS FOR PLANNING DISPOSAL FACILITIESLEGAL AND ORGANIZATIONAL FRAMEWORKSAFETY APPROACHSAFETY DESIGN PRINCIPLESREQUIREMENTS FOR THE DEVELOPMENT, OPERATION AND CLOSURE OFDISPOSAL FACILITIESFRAMEWORK FOR DISPOSALTHE SAFETY CASE AND SAFETY ASSESSMENTSTEPS IN THE DEVELOPMENT, OPERATION AND CLOSURE OF DISPOSAL FACILITIESREQUIREMENTS FOR ASSURANCE OF SAFETYEXISTING DISPOSAL FACILITIES3International Atomic Energy Agency

1. INTRODUCTIONScope• Applies to the disposal of radioactive waste of all types• Establishes requirements to provide assurance ofradiological safety• During the operational period and• Especially in the post-closure period• Does not address• Broader issues of site selection• Transportation of waste to the site
• Non radiological environmental impact• Stakeholder involvement important, but beyond thescope of the standard

4

International Atomic Energy Agency

PROTECTION OF HUMAN HEALTH AND THE
ENVIRONMENT
Post Closure Safety Criteria• The dose limit for members of the public from all planned exposure•

situations is an effective dose of 1 mSv in a year, and this or its risk
equivalent are considered criteria not to be exceeded in the future.
To comply with this dose limit, a disposal facility (considered as a singlesource) is designed so that the estimated dose or risk to therepresentative person who may be exposed in the future as a result of
natural processes affecting the disposal facility does not exceed adose constraint of 0.3 mSv in a year or a risk constraint of the order of
10-5 per year.
Natural processes include the range of conditions anticipated during thelifetime of the facility and events that could occur with a lesser likelihood.
Extremely low probability events would be outside the scope ofconsideration.
5International Atomic Energy Agency

• In relation to the effects of inadvertent human intrusion in the••post-closure period, if such intrusion is expected to lead to anannual dose of less than 1 mSv per year to those living aroundthe site, efforts to reduce the probability of human intrusion or tolimit its consequences are not warranted.
If human intrusion is expected to lead to an annual dose of morethan 20 mSv per year to those living around the site, alternative
disposal options are to be considered, for example disposal of
the waste below the surface, or separation of the radionuclide
content giving rise to the higher dose.
If annual doses in the range 1 – 20 mSv are indicated,reasonable efforts are justified at the facility development stage
to reduce the probability of intrusion or to limit its consequencesby optimization of the facility design.
< 1mSv
Measuresnot warranted

1 – 20 mSv
Measuresconsidered6> 20mSv
Alternative
disposalInternational Atomic Energy Agency

SAFETY REQUIREMENTSDISPOSAL OF RADIOACTIVE WASTEREQUIREMENTS FOR PLANNING DISPOSAL FACILITIES• LEGAL AND ORGANIZATIONAL FRAMEWORK• SAFETY APPROACH• SAFETY DESIGN PRINCIPLESREQUIREMENTS FOR THE DEVELOPMENT, OPERATION ANDCLOSURE OF DISPOSAL FACILITIES• FRAMEWORK FOR DISPOSAL• THE SAFETY CASE AND SAFETY ASSESSMENT• STEPS IN THE DEVELOPMENT, OPERATION AND CLOSURE OFDISPOSAL FACILITIESREQUIREMENTS FOR ASSURANCE OF SAFETYEXISTING DISPOSAL FACILITIES7International Atomic Energy AgencyREQUIREMENTS FOR PLANNING DISPOSALFACILITIESLEGAL AND ORGANIZATIONAL FRAMEWORK8International Atomic Energy Agency

Requirement 1: Government responsibilities
The government is required to provide an appropriate national legal andorganizational framework within which disposal facilities for radioactive waste canbe sited, designed, constructed, operated and closed. This shall include:
confirmation at a national level of the need for different types of disposal facilities;
the definition of the steps in the development and licensing for different types offacility; the clear allocation of responsibilities, the securing of financial and otherresources, and the provision of independent regulatory functions related to eachplanned disposal facility.
Requirement 2: Regulatory body responsibilities
The regulatory body shall establish the regulatory requirements for thedevelopment of each type of disposal facility and shall set out the procedures formeeting the requirements for the various stages of the licensing process. It shallalso set conditions for the development, operation and closure of each individual
disposal facility and shall carry out such activities as are necessary to ensure thatthe conditions are met.

9

International Atomic Energy Agency

Requirement 3: The responsibilities of the operator
The operator of a disposal facility shall be responsible for its safety. The operator
shall carry out safety assessment and develop a safety case, and shall carry out all
the necessary activities for siting, design, construction, operation, closure and, if
necessary post closure surveys, according to national strategy, in compliance withthe regulatory requirements and within the national legal infrastructure.

10

International Atomic Energy Agency

SAFETY APPROACH

11

International Atomic Energy Agency

Requirement 4: Importance of safety in the development process
Throughout the development of a disposal facility, an appropriate understanding of
the relevance and implications for safety of the available options shall be
developed by the operator, for achieving the ultimate goal of providing an
optimized level of operational and post-closure safety.
Requirement 5: Passive safety
The operator shall site, design, construct, operate and close the disposal facility insuch a way that safety is ensured by passive means to the extent possible and thatthe need for actions to be taken after the closure of the facility is minimized.
Requirement 6: Understanding and confidence in safety
The operator of a disposal facility shall develop an adequate understanding of thefacility and its host environment and the factors that influence its post-closure
safety over suitably long time periods, so that a sufficient level of confidence insafety is achieved.

12International Atomic Energy Agency

SAFETY DESIGN PRINCIPLES

13International Atomic Energy Agency

Requirement 7: Multiple safety functions
The host environment shall be selected and the engineered components of thefacility designed and the facility operated so as to ensure that safety is provided bymeans of multiple safety functions. That is, containment and isolation of the waste
shall be provided by means of a number of physical components of the disposal
system whose performance is achieved by diverse physical and chemical
processes together with the various operational controls. The capability of theindividual components and controls together with that of the overall disposal
system to perform as assumed in the safety case shall be demonstrated. The
overall performance of the disposal system shall not be unduly dependent on asingle safety function.
Requirement 8: Containment
The engineered components, including the waste form and packaging, shall bedesigned, and the host environment shall be selected, so as to provide
containment of the waste during the period when radioactive decay has not yet
significantly reduced the hazard posed by the waste and in the case of heatgenerating waste when the waste produces heat energy in amounts that could
adversely affect the performance of the disposal system.

14

International Atomic Energy Agency

Requirement 9: Isolation
The disposal facility shall be sited, designed and operated to provide
features that are aimed at isolation of the radioactive waste from thebiosphere and from humans. The features shall aim to provide isolation
for several hundreds of years for short lived waste and at least several
thousand years for intermediate and high level waste. In doing so,
consideration shall be given to both the natural evolution of the disposal
system and disturbing events.

Requirement 10: Surveillance and control of passive safety features
An appropriate level of surveillance and control shall be applied in orderto protect and preserve the passive safety barriers to the extent that thisis needed in order to fulfil the functions that they are assigned in the postclosure safety case.

15

International Atomic Energy Agency

FRAMEWORK FOR DISPOSAL

16

International Atomic Energy Agency

Requirement 11: Step by step development and evaluation
Disposal facilities shall be developed, operated and closed in a series ofsteps, each supported, as necessary, by iterative evaluations of the site,of the options for design, construction, operation and management, andof the performance and safety of the disposal system.

17

International Atomic Energy Agency

THE SAFETY CASE AND ASSESSMENT

18

International Atomic Energy Agency

Requirement 12: Preparation, approval and use of the safety case and assessment
A safety case and supporting safety assessment shall be prepared and updated
by the operator, as necessary, at each step in the development, operation andpost closure of a disposal facility. They shall be submitted to the regulatory
body for approval. The safety case and supporting safety assessment shall besufficiently detailed and comprehensive to provide the necessary technical input
for informing the regulatory and other decisions needed at each step.

• Progressively developed and elaborated as the project proceeds• Formality and level of technical detail of the safety case depend on the stage ofdevelopment of the project• Establish waste acceptance criteria• Identifies key processes relevant to safety

19International Atomic Energy Agency

Requirement 13: Scope of the safety case and assessment
The safety case for a disposal facility shall describe all the safety relevant aspectsof the site, the design of the facility, and the managerial and regulatory controls.
The safety case and supporting safety assessment shall demonstrate the level ofprotection provided and shall provide assurance to the regulatory body and otherinterested parties that safety requirements will be met.

• Operational safety and post-closure safety• Occupational exposure and public exposure• Normal operations, including anticipated occurrences• Accidents of lesser frequency but significant radiological consequences• Demonstrate disposal system, its possible evolutions and relevant events that might
affect it are sufficiently well understood• feasibility of implementing the design• convincing estimates of the performance of the disposal system• reasonable assurance that all the relevant safety requirements will be compliedwith and radiation protection optimized• analysis of the associated uncertainties• Quantitative assessment over the time period for which regulatory compliance isrequired - results likely to be more uncertain for time periods in the far future• Management systems
20

International Atomic Energy Agency

Requirement 14: Documentation of the safety case and assessment

The safety case and supporting safety assessment shall be documented to a levelof detail and quality sufficient to inform and support the decision to be made ateach step and to allow for their independent review.

• Important considerations are justification, traceability and clarity• Justification concerns explaining the basis for the choices• Traceability concerns the ability of an independent qualified person to follow what hasbeen done
• Clarity concerns good structure and presentation at an appropriate level of detail so
as to allow an understanding of the safety arguments

21International Atomic Energy Agency

STEPS IN THE DEVELOPMENT, OPERATIONAND CLOSURE OF DISPOSAL FACILITIES

22International Atomic Energy Agency

Requirement 15: Site characterization
The site for a disposal facility shall be characterized at a level of detail sufficient tosupport both a general understanding of the characteristics of the site, including
its present condition, its probable natural evolution, possible natural events andalso human plans and actions that may affect the facility or its vicinity over theperiod of interest with regard to safety, and a specific understanding of the impact
on safety of features, events and processes associated with the site and the facility.
Requirement 16: Design
The disposal facility and its engineered barriers shall be designed to contain thewaste with its associated hazard, to be physically and chemically compatible withthe host geological and/or surface environment, and to provide post-closure safety
features that complement those afforded by the host environment. The facility andits engineered components shall also be designed to provide for safety during theoperational period.
Requirement 17: Construction
A disposal facility shall be constructed in accordance with the design as describedin the approved safety case and supporting safety assessment. It shall beconstructed in such a way as to preserve the post-closure safety functions of thehost environment that have been shown to be important by the safety case. The
construction activities shall be carried out to ensure safety during the operationalperiod.
23International Atomic Energy Agency

Requirement 18: Operation
A disposal facility shall be operated in accordance with the conditions of thelicence and the relevant regulatory requirements to maintain safety during theoperational period, and in such a manner as to preserve the post-closure safetyfunctions assumed in the safety case.
Requirement 19: Closure
A disposal facility shall be closed in such a way that provides for the safetyfunctions shown by the safety case to be important for the post-closure period.
Plans for closure, including the transition from active management of the facility,
shall be well defined and practicable, so that closure can be carried out safely at anappropriate time.

24

International Atomic Energy Agency

REQUIREMENTS FOR ASSURANCEOF SAFETY

25

International Atomic Energy Agency

Requirement 20: Waste acceptance
Waste packages and unpackaged waste accepted for emplacement in adisposal facility shall conform to criteria fully consistent with and derived fromthe safety case for the operational and post-closure safety of the disposal
facility.
Requirement 21: Monitoring programmes
A programme of monitoring shall be carried out prior to and during theconstruction and operation of a disposal facility, and after closure, if this ispart of the safety case. This programme shall be designed to collect andupdate the information needed to confirm the conditions necessary for thesafety of workers and members of the public and the protection of theenvironment during the operation of the facility and to confirm the absence ofany conditions that could reduce the post-closure safety of the facility.

26

International Atomic Energy Agency

Requirement 22: Post-closure and institutional controls

An appropriate level of surveillance and control shall be applied in order to protect
and preserve the passive safety barriers to the extent that this is needed in order tofulfil the functions that they are assigned in the post closure safety case. Plans
shall be prepared to address such surveillance and control and the arrangements
for maintaining the availability of information on the disposal facility. These plans
shall form part of the safety case on which authorization to close the facility isgranted.

• Long-term safety not rely on active institutional control• Violation of passive measures will not give rise to the criteria for intervention being
exceeded• Institutional controls not be sole or main component of safety for near surface
disposal• Ability of institutional controls to provide contribution to safety envisaged in the safetycase demonstrated and justified in safety case• Geological and intermediate depth disposal - passive safety barriers sufficiently
robust, unlikely to need repair or upgrading• Intent of surveillance and monitoring - not to measure radiological parameters but toensure the continuing presence of safety functions

27

International Atomic Energy Agency

Requirement 22: Post-closure and institutional controls

•
•
••
•
•
•

Near surface facilities generally designed on the assumption that institutional control willremain in force for a period of time
Near surface disposal of mining and minerals processing waste (very long half lives, largevolumes) activity concentrations limited so safety does not rely on ongoing active
institutional control - waste with greater activity concentrations disposed below surface
Status of disposal facility beyond period of active institutional control - release of the site
for unrestricted use generally not contemplated.
Site location and the facility design will have reduced the likelihood of human intrusion
Near surface facilities - waste acceptance criteria limit consequences of human intrusion
to specified criteria even if control over site lost
Geological and intermediate depth disposal facilities not rely on long term post-closure
institutional control as passive safety function
Whilst facility licensed operator provides control - following licence termination
responsibility will revert to government

28

International Atomic Energy Agency

Requirement 23: Consideration of the System of accounting for and control ofnuclear material
In the design and operation of disposal facilities subject to agreements on
accounting and control of nuclear material, consideration shall be given toensuring that safety is not compromised by the measures required under thesystem of accounting for and control of nuclear material.
Requirement 24: Requirements in respect of security measures
Measures shall be implemented to ensure an integrated approach to safetymeasures and nuclear security measures in the disposal of radioactive waste.
Requirement 25: Management systems
Management systems to provide for the assurance of quality shall be applied toall safety related activities, systems and components throughout all the stepsof the development and operation of a disposal facility. The level of assurance
for each element shall be commensurate with its importance to safety.

29

International Atomic Energy Agency

EXISTING DISPOSAL FACILITIES

30International Atomic Energy Agency

Requirement 26: Existing disposal facilities
The safety of existing disposal facilities shall be assessed periodically until
licence termination and when a safety significant modification is planned orwhen changes with respect to the authorized conditions happen. In the eventthat any safety requirements set down in this publication are not met, measures
shall be put in place to upgrade the safety of the facility, economic and social
factors being taken into consideration.

31

International Atomic Energy Agency

Safety Standards - Disposal

Waste
Disposal

DS 354

Near Surface
DisposalGeological
DisposalManagement
Mining and ofNorm
Processing
Residues

DS 356

DS 334

DS 352
Safety Case &Assessment
for Disposal

DS 355
Monitoring andSurveillance

DS 35732

International Atomic Energy Agency

Contents
1.
2.
3.
4.
5.
6.

INTRODUCTIONDEMONSTRATING THE SAFETY OF RADIOACTIVE WASTEDISPOSAL
SAFETY PRINCIPLES AND SAFETY REQUIREMENTS
THE SAFETY CASE FOR DISPOSALSUPPORTING ASSESSMENT
SPECIFIC ISSUES
Evolution of the safety case
Graded approach
Defence in depth
Robustness
Time frames
Human intrusion
Institutional control
Retrievability of waste
Options appraisal

7.
8.

DOCUMENTING AND USING THE SAFETY CASE
REGULATORY REVIEW PROCESS

33

International Atomic Energy AgencyÅSafety Strategy• Safety objectives• Safety principles• Regulations• Isolation, Containment•Passive systems, robustness•Defence in depth, demonstrabilityÅSafety Case Context

Site and waste characteristics, Safety Functions, Design OptionsÆIntegration of Safety Arguments
Demonstration of robustness, defence in depth
system understanding, monitoring, etc

34International Atomic Energy AgencyÆLimits & conditions e.g. WAC

Management System

Site / Engineering

Operational
SafetyPost-Closureradiological impact

EnvironmentalImpact

Management of Uncertainty

Assessments
ManagementSystem

Iteration & Design Optimization

Stakeholder & Regulatory Involvement

System Description

35International Atomic Energy Agency