Radioactive Contamination in
Scrap and Steel Products
G.K. Panda
Radiological Safety Division
Atomic Energy Regulatory Board
Introduction
•In the recent years there were some reported
cases of detection of low level radioactive
contamination in steel products in India and in
other countries as well
•Most of the cases were because of inadvertent
melting of orphan sources along with the scrap
Challenges or Opportunities???
Definitely- a challenge to
the fraternity
Consequences of radioactive
contamination
•
•
•
•
•
Exorbitant economical loss
Health hazard to the workers
and public at large, though
most of the time it is low
Anxiety among the workers and
public about the health
consequences
Bad name to the company
Bad name to the country
Mission of AERB
"The mission of AERB is to ensure that the
use of ionizing radiation and nuclear energy
in India does not cause unacceptable
impact on the health of workers and the
members of the public and on the
environment."
What AERB is doing
•
Educate
•
Alert
•
Guidance
•
Interacting with various Governmental
agencies
How radioactive sources look like?
•Very small
•Doubly encapsulated in SS
•Further shielded according to their strength
How radioactive sources look like?
Very small
Doubly encapsulated in SS
Further shielded according to their strength
Radiation warning symbol
Radiography Device
Source Containers
Loss of Control of a Radioactive Source
Intentional
Inadvertent
• Loss of, or
damage to sources
• Misplaced
• Forgotten
• Accidents
Damage
(Sabotage)
Malevolent Motive
•Terrorism
•Individual’s intent
to harm other(s)
Acquisition
•Theft
•Illegal purchase
•Legal purchase
Financial Motive
•Illegal sale for profit
•Avoidance of costs
of
ownership
dumping
to
avoid
disposal fees
•Extortion
Flow of radioactive contamination
Radioactive material in the Steel metal scrap
Gets Melted in the Furnace
Rolled/Forging in Steel Mills
Manufacture of final consumer product
Exported or supplied to a dealer
Reaches to end user
Economical impact of
contamination.
Calculation based
 on the inputs received from an Indian exporter
• material steel grade 304 exported to an European
destination and returned to India after detection of
contamination at the port of destination
• Price index prevailed in steel market in Aug , 2008.
Detection
• RAM can be detected in the metal scrap
stream by monitoring the metal scrap in the
following way.
 Administrative Monitoring
 Visual Monitoring
 Radiation Monitoring
Administrative Monitoring
• The following administrative procedures
can provide a first indication of whether
there is a significant
potential for
radioactive scrap metal to be present in
consignments
 Knowledge of the origin of the scrap
metal
 Knowledge of the scrap metal supplier
 The history of previous transactions
Visual Monitoring
• Metal scrap should be visually monitored
during its handling at scrap yards, melting
plants and institutions involved with value
addition
• Persons handling scrap should be trained
to recognize the different types of radiation
sources, source housings and radioactivity
warning signs.
Radiation Labels on Packages
Radiography Device
Source Containers
Supplementary Ionizing Radiation
Warning Symbol; from Feb. 2007
Radiation Monitoring
• Possible presence of radioactive material
in scrap metal and finished products should
be checked for radiation using fixed
and/or portable monitors.
Radiation Monitoring
Important Characteristics of Equipment
• Serve the intended purpose (energy independent etc.)
• Optimal utilization (e.g. portability)
• Minimal requirements for operation training and ease of
operation
• Highest efficiency and sensitivity
• Reliability
• Work in wide temperature and humidity range
• Cost effective
Detection Probability
Alpha
Negligible
Beta
Very Low
Gamma
High
Neutrons
High (with neutron
monitors)
Location of Radiation Monitoring
• Monitoring outside of a container as a whole
while entering the industry
• At the time of unloading the scrap
• At the time of filling the charge bucket
• After manufacturing of products like metal
sheets, billets, ingots
• In the laboratory while performing the
composition analysis
• Monitoring of slag and off-gas dust
• At the time of containers leaving the industry
with finished products
Monitoring of Scrap
• Fixed Monitors
• Location: weigh bridge/entrance of the
institute
• Speed of truck carrying the scrap container
should be less than 8 km./h;
Monitoring of Scrap…
• Portable Monitors
• Location: any accessible place
• Speed of the monitor should be less than 0.2
m/sec.
• Weight should be less than 2 kg.
Determination of an instrument
threshold
• As we all are aware of the fact that
background radiation levels at different places
are different (in most of the places it is in the
range of 5-15 µRem/h).
• Even at a particular location the background
radiation level fluctuates
• So, it is very difficult, to give a universally
acceptable threshold radiation level at which
appropriate actions to be initiated
Fluctuation in background
readings
• It is a common question that up to what
background variation it is acceptable.
• As a rule of thumb, the fluctuation in the
reading is considered to be within two times
of square root of an observed reading at any
time (say, x µrem/h) i.e. the readings should
fall within the range x ± 2 √x µrem/h.
Fluctuation in background
readings…
• For example, if the observed reading is 9
µrem/h, then the fluctuation can be taken as
(2x3) µrem/h i.e. 6 µrem/h. This means the
expected readings should fall in the range 3
to15 µrem/h.
• For readings to fall with in x ± 2 √x; confidence
level is 95 %.
Response to the alarms
• Once an alarm is confirmed as genuine
alarm, cordon off the area around the
container and ensure that the radiation
level at cordon does not exceed 0.1 mR/h
(1 µSv/h)
• At the cordoned off area, it is required to
display radiation caution symbol and a
placard mentioning “RADIATION AREA-KEEP
AWAY” at a prominent location
Response to alarms.. (Emergency
management)
• Very unlikely to get a bare source in the scrap
• If any metallic container or object with
radiation warning symbol
found, or any
metallic container with unusually heavy
weight w.r.t. its shape, size etc
– do not remain near it
– cordon off the area
– do not allow unauthorised entry nearby
– inform AERB immediately @
Emergency management……
Head, Radiological Safety Division
Atomic Energy Regulatory Board
Anushaktinagar, Mumbai – 400 094
Ph No. 022 25990655/656, Fax No. 25990650
E-mail: sahussain @aerb.gov.in
National/International Trade
• Before selling their products, the sellers
should ascertain that up to what
contamination level it is acceptable to the
buyer and to the country.
Summary
i. Radiation contamination free certificate
ii. Radiation monitoring at various stages
Management Mantra
Learning of lessons:
i. From own mistakes- may cost crores of
rupees to the affected party because of
radioactive contamination
ii. From other’s mistakes- free of cost
Thanks for your kind
Attention!!