lec 4:regulatory reqs Flashcards
- International Guides
✓IAEA-TECDOC-1791, Considerations on the Application of the International
Atomic Energy Agency (IAEA) Safety Requirements for the Design of Nuclear
Power Plants
✓IAEA document SSR-2/1, Safety of Nuclear Power Plants,
- United States Regulations
✓Appendix A to Part 50—General Design Criteria for Nuclear Power Plants,
United States Nuclear Regulatory Commission (USNRC)
- Canadian Regulations
✓Design of Reactor Facilities: Nuclear Power Plants”, Regulatory Document
REGDOC2.5.2, Canadian Nuclear Safety Commission (CNSC), 2014. (A short
version by me on Brightspace for you)
✓Other REGDOCs available example, REGDOC 2.4.1 and 2.4.2
IAEA document
SSR-2/1, Safety
of Nuclear Power
Plants: Design
Publication used primarily for land based
stationary nuclear power plants with
water cooled reactors designed for
electricity generation or for other heat
production applications (such as district
heating or desalination).
* May also be applied, with judgement, to
other reactor types, to determine the
requirements that must be considered in
developing the design
* Canadian Regulator makes reference to
SSR-2/1
Canadian Nuclear Regulator
Canadian Nuclear Safety Commission (CNSC)
Established May 2000, under the Nuclear Safety and
Control Act (NSCA)
✓Replaced the AECB, established in 1946, under the
Atomic Energy Control Act
▪ Established same time as Atomic Energy Act of
1946 in US (Why 1946?)
Canadian Nuclear Regulator
Canadian Nuclear Safety Commission (CNSC) purpose
- The CNSC regulates all nuclear-related facilities and
activities
✓Does not promote any nuclear technology
✓Ensure nuclear facilities and/or activities are safe
CNSC Mission
- To protect the health, safety and security of persons and the
environment; and to implement Canada’s international
commitments on the peaceful use of nuclear energy
✓ The licensee is the cornerstone of safety and is held
accountable by their licence
Accountability of Licensee/Proponent: * No licence may be issued, renewed, amended or replaced
unless, in the opinion of the Commission, the applicant:
- Section 24(4) of the Nuclear Safety and Control Act
✓is qualified to carry on the activity that the licence will
authorize the licensee to carry on; and
✓will, in carrying on that activity, make adequate
provision for the protection of the environment, the
health and safety of persons and the maintenance of
national security and measures required to implement
international obligations to which Canada has agreed
CNSC
Regulatory
Framework : SLIDE 13
Nuclear safety and Control Act: Class I Nuclear Facilities Regulations
Provide requirements for site preparation licence applications,
personnel certifications, record-keeping and sets timelines for
regulatory reviews.
Apply to: Class 1A and Class 1B nuclear facilities including
nuclear reactors, large particle accelerators, nuclear processing
plants, fuel fabrication plants and waste disposal facilities
CNSC Design
Requirements
CNSC expects the applicant to demonstrate their safety case is
commensurate with the risks posed by the facility.
* For any size reactor, this allows for the use of a graded approach to safety.
* CNSC have regulated NPPs to small reactors using this approach. This is
consistent with IAEA standards
slide 16
Nuclear power plant (NPP):
a fission
reactor with a thermal power approx.
greater than 200 MWt (about 75 MW
electrical output)
Small reactor
a fission reactor
with a thermal power approx.
less than 200 MWt
Concept of Graded Approach In Regulation
Factors to be considered in applying graded approach include:
- reactor power
- reactor safety characteristics
- passive safety features
- amount and enrichment of fissile material
- fuel design
- type and mass of moderator, reflector and coolant
- presence of high-energy sources and other radioactive and
hazardous sources - safety design features
- source term (release in case of accident)
- intended utilization of the reactor
- siting/proximity to populated areas
- proven design (knowledge and experience)
Graded Approach - Examples
- Requirements are not gradable; fulfilling fundamental safety
functions, such as shutting down the reactor, core cooling and
containment of radioactive material, are not gradable. - The way in which the requirement is met may be graded.
Graded approach may be applied to:
✓design of shutdown means
✓confinement/containment features depending on the
safety characteristics of the reactor design
✓For example in safety analyses
▪ the scope, extent and detail of these analyses may
be significantly reduced because certain accident
scenarios may not apply or may need only a limited
analysis
General Nuclear Safety Objective
- Nuclear power plants (NPPs) must be designed and operated in a manner that will protect
individuals, society and the environment from harm - The general nuclear safety objective is supported by three complementary safety objectives:
General Nuclear Safety Objective
SLIDE 20
Technical Safety Objective
see slide 21 AND 22
Three types of safety assessments shall be carried out
✓ To identify all sources of exposure in order to evaluate potential radiation doses to
plant workers and the public, and the effects on the environment
hazard
deterministic safety (DSA)
Probabilistic saFety (PSA)
SAFETY GOALS
Protection such that there is no
significant additional risk to the life
and health of individuals
Safety goals
Societal risk comparable to or less than
the risks of generating electricity by
viable completing technologies
Core damage frequency: <10-5
/year
Small release frequency (>1000 TBq of
I-131): <10-5
/year
Large release frequency (>100 TBq of
Cs-137): <10-6
/year
Defence in
Depth
Principle: * As per CNSC REGDOC-2.5.2, Design of Reactor
Facilities:
✓ defence in depth is to ensure overlapping
provisions are applied to all
organizational, behavioural, and designrelated safety and security activities
✓ provisions for all five levels of defence
(later in presentation)
✓ balanced provisions for prevention and
mitigation
▪ imbalance: e.g., prevention with
inadequate mitigation or mitigation
with little prevention
Fundamental
Safety
Functions of a
Nuclear Reactor
Control of reactivity
Removal of heat from the fuel
Confinement of radioactive material
Shielding against radiation
Control of operational discharges and
hazards substances, as well as
limitation of accidental releases
Monitoring of safety-critical
parameters to guide operator actions
