Structural Integrity

1. INDIAN STRUCTURAL INTEGRITY SOCIETY
Workshop on Structural Integrity
Assessment of Nuclear Energy Assets
9th – 10th May 2018
AERB Auditorium, Niyamak Bhavan-B, Mumbai

2. Safety and Criticality of nuclear systems –
Regulatory perspectives
S A Bhardwaj
AERB

3. FUNDAMENTAL SAFETY OBJECTIVE
All stages in the lifetime of a nuclear power plant, including
planning, siting, design, manufacture, construction, commissioning
and operation, as well as decommissioning Protection of workers,
public and the environment from harmful effects of ionising
radiation .

4. Discovery of Radioactivity
• In late 1895, a German physicist, W. C.
Roentgen while working with a cathode ray
tube found that the rays generated would pass
through most substances casting shadows of
solid objects on pieces of film. He named the
new ray X-ray, because in mathematics "X" is
used to indicated the unknown quantity.
• One of Roentgen’s first experiments late in
1895 was a film of his wife Bertha's hand with
a ring on her finger

5. Discovery of Radioactivity
• In 1896, Henri Becquerel, France, accidentally
discovered the radioactivity, when he noticed
that uranium emitted invisible rays that were
able to pass through protective black paper and
left an impression on photographic plates.
• In 1898, Dr. Pierre and Marie Curie, France
discovered that uranium ore contained two
other elements, radium and polonium, which
were much more radioactive than uranium.
• All three were jointly awarded the Nobel Prize
in 1903.

6. Ionisation

8. Ionising Radiation
• Radiation is said to be “ionizing” when it has enough
energy to eject one or more electrons from the atoms or
molecules in the irradiated medium.
• Produces ion pair.
• The ions will upset chemical bond.
• Can result in cell damage by affecting the DNA.

9. 200 Mev
The fission of an atom of uranium produces million times the
energy produced by the combustion of an atom of carbon
from coal.
FISSION

10. Ionizing Radiation
 Radiation emitted from radiation sources
(i.e. radioactive material and radiation generating
machines such as X-ray) can cause ionization.
 Ionizing radiation
 Alpha
 Beta
 Gamma
 X-Rays
 Neutron particles

11. Ionizing Radiation
Paper Wood Concrete
Alpha
Beta
Gamma( and X Rays)

12. FISSION CHAIN REACTION
Possibly in
fertile material

13. WHAT IS FERTILE MATERIAL
Fertile U-238 + Neutron Pu-239 Fissile
Fertile Th-232 + Neutron U-233 Fissile
Since fuel contains both, fissile and fertile materials, additional fissile
material is invariably produced in a reactor along with power generation.

14. Nuclear Reactor
•Produces
–Power
–as well as converts Fertile
materials to Fuel

15. Leftovers of Fission reaction
in Natural U
-Fission products (Radioactive)
-Unused Uranium
-Pu-239
By REPROCESSING
unused U & Pu-239 can be separated for
further use.

16. STAGE 1 STAGE 2 STAGE 3
U- 233
ELECTRICITY
Depleted U
Pu
300 GWe, 30 Yr
Pu FUELLED
FAST BREEDERS
Th
500 GWe, 500 Yr
ELECTRICITY
U- 233 FUELLED
BREEDERS
Natural
Uranium
ELECTRICITY
PHWR
12 GWe, 30 Yr
Th
Pu
U- 233
Overview of Three Stage Nuclear
Power Programme

17. Is there
Ionising
RADIATION
in this Room?
Yes, it is

18. Radiation is Everywhere
We live in a sea of radiation…
Cosmic
Inhaled Radon
Rocks
Radioactive Elements
Plants
Bodies

19. 10
100
1000
10000
100000
1000000
70000
13000
Insignificant Health Effect
Natural
1
At boundary of nuclear power plant
1 Thyroid Scan
1 Thallium Cardiac Stress Test
1 Chest CT Scan
1 Chest X ray
One hour air flight
Micro Seiverts/ yr
Regulatory limit for Public
and ALARA
MAN MADE

20. Deterministic Effects

21. Stochastic Effects

22. Acetaldehyde (from consuming alcoholic beverages)
Acheson process, occupational exposure associated with
Acid mists, strong inorganic
Aflatoxins
Alcoholic beverages
Aluminum production
4-Aminobiphenyl
Areca nut
Aristolochic acid (and plants containing it)
Arsenic and inorganic arsenic compounds
Asbestos (all forms) and mineral substances (such as talc or vermiculite) that contain asbestos
Auramine production
Azathioprine
Benzene
Benzidine and dyes metabolized to benzidine
Benzo[a]pyrene
Beryllium and beryllium compounds
Betel quid, with or without tobacco
Bis(chloromethyl)ether and chloromethyl methyl ether (technical-grade)
Busulfan
1,3-Butadiene
Cadmium and cadmium compounds
Chlorambucil
Chlornaphazine
Chromium (VI) compounds
Clonorchis sinensis (infection with), also known as the Chinese liver fluke
Coal, indoor emissions from household combustion
Coal gasification
Coal-tar distillation
Coal-tar pitch
Coke production
Cyclophosphamide
Cyclosporine
1,2-Dichloropropane
Diethylstilbestrol
Engine exhaust, diesel
Epstein-Barr virus (infection with)
Erionite
Estrogen postmenopausal therapy
Estrogen-progestogen postmenopausal therapy (combined)
Estrogen-progestogen oral contraceptives (combined) (Note: There is also convincing evidence in humans that these agents
confer a protective effect against cancer in the endometrium and ovary)
Ethanol in alcoholic beverages
Ethylene oxide
Etoposide
Etoposide in combination with cisplatin and bleomycin
Fission products, including strontium-90
Fluoro-edenite fibrous amphibole
Formaldehyde
Haematite mining (underground)
Helicobacter pylori (infection with)
Hepatitis B virus (chronic infection with)
Hepatitis C virus (chronic infection with)
Human immunodeficiency virus type 1 (HIV-1) (infection with)
Human papilloma virus (HPV) types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 (infection with) (Note: The HPV types that have
been classified as carcinogenic to humans can differ by an order of magnitude in risk for cervical cancer)
Human T-cell lymphotropic virus type I (HTLV-1) (infection with)
Ionizing radiation (all types)
Iron and steel founding (workplace exposure)
Isopropyl alcohol manufacture using strong acids
Kaposi sarcoma herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8) (infection with)
Leather dust
Lindane
Magenta production
Melphalan
Methoxsalen (8-methoxypsoralen) plus ultraviolet A radiation, also known as PUVA
4,4'-Methylenebis(chloroaniline) (MOCA)
Mineral oils, untreated or mildly treated
MOPP and other combined chemotherapy including alkylating agents
2-Naphthylamine
Neutron radiation
Nickel compounds
N'-Nitrosonornicotine (NNN) and 4-(N-Nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK)
Opisthorchis viverrini (infection with), also known as the Southeast Asian liver fluke
Outdoor air pollution (and the particulate matter in it)
Painter (workplace exposure as a)
3,4,5,3',4'-Pentachlorobiphenyl (PCB-126)
2,3,4,7,8-Pentachlorodibenzofuran
Phenacetin (and mixtures containing it)
Phosphorus-32, as phosphate
Plutonium
Polychlorinated biphenyls (PCBs), dioxin-like, with a Toxicity Equivalency Factor according to WHO (PCBs 77, 81, 105, 114, 118,
123, 126, 156, 157, 167, 169, 189)
Processed meat (consumption of)
Known human carcinogens Group 1: Carcinogenic to humans

23. •Ionizing radiation (all types)
•Iron and steel founding (workplace exposure)
•Isopropyl alcohol manufacture using strong acids
•Kaposi sarcoma herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8) (infection with)
•Leather dust
•Lindane
•Magenta production
•Melphalan
•Methoxsalen (8-methoxypsoralen) plus ultraviolet A radiation, also known as PUVA
•4,4'-Methylenebis(chloroaniline) (MOCA)
•Mineral oils, untreated or mildly treated
•MOPP and other combined chemotherapy including alkylating agents
•2-Naphthylamine
•Neutron radiation
•Nickel compounds
•N'-Nitrosonornicotine (NNN) and 4-(N-Nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK)
•Opisthorchis viverrini (infection with), also known as the Southeast Asian liver fluke
•Outdoor air pollution (and the particulate matter in it)
•Painter (workplace exposure as a)
•3,4,5,3',4'-Pentachlorobiphenyl (PCB-126)
•2,3,4,7,8-Pentachlorodibenzofuran
•Phenacetin (and mixtures containing it)
•Phosphorus-32, as phosphate
•Plutonium
•Polychlorinated biphenyls (PCBs), dioxin-like, with a Toxicity Equivalency Factor according to WHO (PCBs 77, 81, 105, 114, 118,
123, 126, 156, 157, 167, 169, 189)
•Processed meat (consumption of)
•Radioiodines, including iodine-131
•Radionuclides, alpha-particle-emitting, internally deposited (Note: Specific radionuclides for which there is sufficient evidence for
carcinogenicity to humans are also listed individually as Group 1 agents)
•Radionuclides, beta-particle-emitting, internally deposited (Note: Specific radionuclides for which there is sufficient evidence for
carcinogenicity to humans are also listed individually as Group 1 agents)
Known human carcinogens Group 1: Carcinogenic to humans (contd.)
•Radium-224 and its decay products
•Radium-226 and its decay products
•Radium-228 and its decay products
•Radon-222 and its decay products
•Rubber manufacturing industry
•Salted fish (Chinese-style)
•Schistosoma haematobium (infection with)
•Semustine (methyl-CCNU)
•Shale oils
•Silica dust, crystalline, in the form of quartz or cristobalite
•Solar radiation
•Soot (as found in workplace exposure of chimney sweeps)
•Sulfur mustard
•Tamoxifen (Note: There is also conclusive evidence that tamoxifen reduces the risk of
contralateral breast cancer in breast cancer patients)
•2,3,7,8-Tetrachlorodibenzo-para-dioxin
•Thiotepa
•Thorium-232 and its decay products
•Tobacco, smokeless
•Tobacco smoke, secondhand
•Tobacco smoking
•ortho-Toluidine
•Treosulfan
•Trichloroethylene
•Ultraviolet (UV) radiation, including UVA, UVB, and UVC rays
•Ultraviolet-emitting tanning devices
•Vinyl chloride
•Wood dust
•X- and Gamma-radiation

24. • Long term effects of low doses of radiation are still
unknown and is a topic for research/debate.
• Current assumption is of Linear non-threshold (LNT)model
assuming
“Radiation is harmful at all doses, even low ones”
• A very conservative model (Does not account for
cellular repair process in human body)
Stochastic Effects of low Radiation Doses

25. Regulations are based on “reduce
radiation to
As Low As Reasonably Achievable
(ALARA),”

26. uses of ionising radiation
• Diagnosis
• Treatment
• Sterilisation medical, health, industry, agriculture,
sewage waste and research purposes.
• Non Destructive Testing
• Nucleonic gauges
• Security monitoring
• Oil and Gas exploration
• Manufacturing
• ……..

27. A Nuclear Power Plant

28. Thermal and Nuclear Energy
Thermal Nuclear

29. BOILING WATER REACTOR
Reactor Vessel with Boiling
Turbine Generator
(Conventional)

30. PRESSURISED WATER REACTOR
Turbine Generator
Pressure Vessel - REACTOR
Steam Generator

31. Cut away view of Pressure Vessel – Reactor (VVER)

32. PRESSURISED HEAVY WATER REACTOR
Reactor

33. ZIRCALOY
CLADDING
UO2 FUEL PELLET
FUEL ELEMENT

34. Fuel Pellet
Fuel Clad
Fuel Pencil
FUEL BUNDLE

36. Special technological aspects &
SAFETY

37. 200
MeV
200 Mev

38. Some important Fission Products
ISOTOPE HALF LIFE
I-131 8.01 d
I-132 2.23 hr
I-133 20.8 hr
I-134 52.5 min
I-135 6.57 hr
Cs-134 2.07 y
Cs-137 30.14 y
Kr-85 10.7 y
Kr-87 1.27 hr
Kr-88 2.83 hr
Xe-133 5.24 d
Xe-135 9.1 hr
Xe-138 14.17 min

39. Activation of Reactor Components

40. CONSTRAINTS DUE TO RADIATION IN LIFE
MANAGEMENT/MAINTENANCE OF NUCLEAR PLANTS
• normal maintenance,
• special maintenance,
• Refuelling,
• in-service inspection, and
• radioactive waste handling, decommissioning.

41. ZIRCALOY
CLADDING
UO2 FUEL PELLET
FUEL ELEMENT
First Barrier
Second Barrier

42. •Heat produced should be
equal to heat removed
at all times
Including even when plant is not
operating

43. 0 5 10 15 20 25 30
RelativePower
time(days) after shutdown
Decay heat curve
100
2
1

44. What happens if not able to cool?

45. Loss of coolant Accident &
Emergency Core Cooling
Pre-Test Configuration (radial) Post-Test Configuration (radial)
37-
ELEMENT
BUNDLE
Post-Test
Configuration (axial)

47. Fission Products
ISOTOPE HALF LIFE
I-131 8.01 d
I-132 2.23 hr
I-133 20.8 hr
I-134 52.5 min
I-135 6.57 hr
Cs-134 2.07 y
Cs-137 30.14 y
Kr-85 10.7 y
Kr-87 1.27 hr
Kr-88 2.83 hr
Xe-133 5.24 d
Xe-135 9.1 hr
Xe-138 14.17 min

48. Hydrogen Formation
•Reactors are cooled by water.
•Water is hydrogen and oxygen.
•Any corrosion process (as slow rusting in iron)
absorbs oxygen from water and releases hydrogen
free.
•The corrosion reaction on zircaloy, a metal used to
cover fuel, becomes excessive at high temperature.
•Therefore when fuel over heats, because of lack of
cooling, any interaction with water or its vapour
provides oxygen for the corrosion reaction and
hydrogen is left free at a fast rate.

49. Barriers

50. How safety is built into design

51. MULTIPLE PHYSICAL BARRIERS
and APPLICATION OF DEFENSE IN DEPTH
The defence in depth approach is
about creating multiple layers, each
independent of other as far as
practicable, of safety provisions to
ensure public safety.
.
DID
Level 5
Level 4
Level 3
Level 2
Level 1

52. LEVEL 1 prevent deviations from normal operation and the failure of items important to safety
Enhance prevention by selection of appropriate design codes and materials, and to the quality
control of the manufacture of components and construction of the plant, as well as to its
commissioning, use of proven engineering practices, ease of access, appropriate design options etc
LEVEL 2 to detect and control deviations from normal operational states in order to prevent
anticipated operational occurrences at the plant from escalating to accident conditions.
Give priority to advanced control and monitoring systems with enhanced reliability,
intelligence and the ability to anticipate and compensate abnormal transients.
LEVEL 3 Control of accidents within the design basis
inherent and/or engineered safety features, safety systems and procedures be capable of
preventing damage to the reactor core or preventing radioactive releases
requiring off-site protective actions and returning the plant to a safe state

53. LEVEL 4 Control of severe plant conditions; only protective actions that are limited in terms
of lengths of time and areas of application would be necessary and that off-site
contamination would be avoided or minimized
Increase reliability and capability of systems to control and monitor complex accident
sequences; decrease expected frequency of severe plant conditions;
LEVEL 5 mitigate the radiological consequences of radioactive releases that could potentially
result from accidents.
This requires the provision of adequately equipped emergency response facilities and
emergency plans and emergency procedures for on-site and off-site emergency response.
Avoid the necessity for evacuation or relocation measures outside the plant site.

54. Safety in Design
• ensure that for all the postulated credible accidents are taken into account in the design
prevent accidents with harmful consequences resulting from a loss of
control over the reactor core or other sources of radiation, and
• To mitigate the consequences of any accidents that do occur.
• ensure that the likelihood of occurrence of an accident with
serious radiological consequences is extremely low

55. DESIGN OF NPP TO ACHIEVE HIGH RELIABILITY
Safety classification: on the basis of their function and their safety significance.
Engineering design rules based on relevant national or international codes and
standards and with proven engineering practices, with due account taken of their
relevance to nuclear power technology.
Physical separation and independence of safety systems
Eliminate possibility of common cause failures

56. • Single Failure Criterion
• Fail-safe design
• Use of Passive features ( not requiring prime
movers using active power source)

57. Proven Engineering Practices
• Codes and standards that are used as design rules for items important
to safety shall be identified and evaluated to determine their
applicability, adequacy and sufficiency, and shall be supplemented or
modified as necessary to ensure that the quality of the design is
commensurate with the associated safety function.
• a new design or feature is introduced or where there is a departure
from an established engineering practice, safety shall be demonstrated
by means of appropriate supporting research programmes,
performance tests with specific acceptance criteria, or the examination
of operating experience from other relevant applications.

58. • Structures, systems, and components important to safety be designed,
fabricated, erected, and tested to quality standards commensurate with
the importance of the safety function to be performed.
• components that are part of the reactor coolant pressure boundary be
designed, fabricated, erected, and tested to the highest practical quality
standards.
• ASME standards committees develop improved methods for the
construction and in service inspection (ISI) of ASME Class 1, 2, 3, MC
(metal containment), and CC (concrete containment) nuclear power
plant components

59. Boiler and Pressure Vessel Code
Sections
Section I - Power Boilers
Section II - Materials
Section III - Rules for Construction of Nuclear Facility
Components
Section IV - Heating Boilers
Section V – Non destructive Examination
Section VI - Recommended Rules for the Care and
Operation of Heating Boilers
Section VII - Recommended Guidelines for the Care of
Power Boilers
Section VIII Pressure Vessels
Section IX - Welding and Brazing Qualifications
Section X - Fiber-Reinforced Plastic Pressure Vessels
Section XI - Rules for In-service Inspection of Nuclear
Power Plant Components
Section XII - Rules for the Construction and Continued
Service of Transport Tanks
Division 1
– Metallic Components
• Division 2
– Code for Concrete Reactor Vessels and Containments
• Division 3
– Containment for Transportation and storage of Spent Nuclear
Fuel and High-Level Radioactive Waste
• Division 4
– Magnetic Confinement Fusion Energy Devices
• Division 5
– High Temperature Reactors Division 1
Subsection NB Class 1 Components
Subsection NC Class 2 Components
Subsection ND Class 3 Components
Reactor Pressure Vessel
Steam Generator
Reactor Coolant Pump casing
Reactor Coolant Piping
Subsection NB
Class 1 Components
ECCS
Containment
Storage tanks
Post accident heat removal
Subsection NC
Class 2
Components

60. Safety Assessment
• Safety assessment is the systematic process that is carried out throughout the design process to
ensure that all relevant safety requirements are met by the proposed or actual design of the
plant. Safety assessment includes, but is not limited to, the formal safety analysis.
• Comprehensive deterministic safety assessments and probabilistic safety assessments
• Safety analysis carries out a detailed analysis of all the postulated events which are likely to
occur during the life time of the reactor.
• In addition it also analyzes rare events which may not occur ever but have serious consequences.
• This is carried out to provide cost effective design improvements which may significantly reduce
the consequences. This may also provide indicators and support for emergency preparedness.
• Accident analysis is a subset of safety analysis and does not include safety during normal
operation and operating transients

61. Provision for Construction
• Items important to safety for a nuclear power plant shall be designed so that
they can be manufactured, constructed, assembled, installed and erected in
accordance with established processes, that ensure the achievement of the
design specifications and the required level of safety.
• In the provision for construction and operation, due account is taken of
relevant experience that has been gained in the construction of other similar
plants and their associated structures, systems and components. Where
practices from other relevant industries are adopted, such practices are
shown to be appropriate to the specific nuclear application.

62. Features to Facilitate Radioactive Waste
Management and Decommissioning
• The choice of materials, so that amount of radioactive waste will be
minimised to the extent practicable and decontamination will be
facilitated.
• The facilities necessary for the treatment and storage of radioactive
waste generated in operation and provision for managing the
radioactive waste that will be generated in the decommissioning of
the plant.

63. Design Considerations for In service Inspection
• accessibility to areas and feasibility of the examination
• Adequate shielding consideration
• Adequate provision for removal, storage and installation of structural members, shielding
components, insulating materials and other equipment
• Provisions to enable examinations remotely to reduce radiation exposure;
• Adequate space in the plant layout for installation of supports, handling machinery, fixtures,
platforms etc. to facilitate removal, disassembly, reassembly, placing and mounting of inspection
equipment and/or probes;
• Provision for repair or replacement of systems or components due to observed structural defects or
flaw indications;
• Provision of test coupons for assessing ageing effects of various operating conditions such as load,
temperature, radiation etc., on material properties

64. AERB Codes and Guides
Nuclear Facilities
Fuel Cycle Facilities
NPP - Siting
NPP - Design
NPP - Operation
NPP – Quality Assurance
Radiation Facilities
Transport of Radioactive Material
Gamma Irradiators
Industrial Radiography
Medical Applications involving Radiation
Ionising Gauging Devises
Accelerators and Cyclotron Facilities
Radioactive Sources
Consumer Products involving Radiation
AERB has so far issued more than 160
Regulatory Documents

65. Conclusion:
Safety of nuclear systems critically depends on
structural integrity. The designer, manufacturer,
quality control, operation....even regulator all
have to play their role well.

66. ProSIM R and D Pvt Ltd
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Indian Structural Integrity Society (InSIS)
Website: www.instint.in
Contact us: insisblr@gmail.com