Radiation Awareness Presentaion [Compatibility Mode]

7/31/2019 Radiation Awareness Presentaion [Compatibility Mode]

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RADIATION APPRECIATION

COURSE

THE USE OF IONISING RADIATION FOR

Types of radiation sources & Biological effects of radiation

Typical equipment used on site

Emergencies & protection


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LEGAL REQUIREMENTS

Ionising Radiation Regulations 1999

Working with Ionising Radiation ACOP 1999

Radioactive Substances Act 1993


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TYPES OF RADIATION SOURCES

& BIOLOGICAL EFFECTS

TYPES OF RADIATION

(RADIOACTIVE DECAY) X-RAY

ALPHA BETA GAMMA

Yb 169Se 75Ir 192Co 60


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UNITS OF RADIATION

There are three principle units we need to be aware of:- Activity - which is the measure of quantity of a radioactive source

defined in terms of the number of nuclear transformations per second

and is expressed as the Bequerel - 1 disintegration / second.

Absorbed Dose - which is a measure of energy deposited in aparticular material from radiation and is expressed as the

Gray - 1 joule / kilogramme

Dose Equivalent - which is the absorbed dose modified by a quality

factor (Q) to take in the different biological effect of different types of

radiation and is expressed as the Sievert - Gray X Q.

For the type of radiation we are concerned with the Gray and Sievert

are the same.


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Radiation Travels In Straight Lines

Radiation Travels At The Speed Of Light

IONISING RADIATION KEY FACTS

Radiation Penetrates Matter

Radiation Can Impair Or Destroy Living Cells

Radiation Can Not Be Detected By Human Senses


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RADIATION EFFECTS ON BIOLOGICAL TISSUE

DEPOSITS ENERGY IN CELLS

99% DISSIPATED AS HEAT

(NEGLIGIBLE RISE IN

TEMPERATURE)

1% CAUSES CHEMICAL

CHANGES.

(RESULTS IN DAMAGE TO

CHROMOSOME PROTEIN etc)

DESTROYS

CELLS

DAMAGES

CELLS

CAN IMPAIR THE CELLS ABILITY TO REPRODUCE

ITSELF. THIS CAN BE MORE CRITICAL IN CELLS

THAT REPRODUCE RAPIDLY, SUCH AS THOSE IN

BLOOD FORMING ORGANS


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DOSES IN PERSPECTIVE (SPECTRUM OF DOSES)

Spectrum of Doses Approximate Dose

Annual Dose Limit for Classified Workers 20 mSv/YearAverage Radiation worker 4 mSv/Year

Annual Dose Limit for Other persons 1 mSv

Background (Natural), UK 1.9 mSv/Year

Back round, Other laces in the World 0.5mSv to 260 mSv/Year

(0.5 mSv average 260 mSv Ramsar Iran)

Typical dose from a chest X-Ray 0.3 mSv

Detectable damage to Chromosome 100 mSv

Detectable blood count change 300 mSv

Radiation sickness > 1 Gray (Body)

Death > 3 Gray (Body)


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TYPICAL EQUIPMENT USED FOR

RADIOGRAPHY ON SITE


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TYPICAL ISOTOPE SOURCE HOLDER

The radioactive isotope

is usually disc shaped

and is typically 2mm

diameter and 2mm in

.

This radioactive disc is

welded into a precision

made tungsten holder

Source


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GAMMA RADIOGRAPHY PROJECTOR SYSTEMS

Source Guide Tube Source Projectors Control Unit


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TYPICAL EQUIPMENT USED FOR RADIOGRAPHY

Equipment includes:-

Isotope container

Guide tube

Control mechanism

Collimation(Shielding)

Radiation monitor

TLD


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HUMAN SENSES

Radiation Can Not Be Detected By Any Of The Human

Senses

Radiation Monitors Are The Eyes And Ears Of The

Radiographer


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RADIATION (SURVEY) MONITORS

The radiation monitor is the

eyes and ears of the

radiographer.

They contain a Geiger-Muller

or similar tube, which detects

.

They also measure the

radiation dose level.

The monitor has a graduated

scale and an audible indicator

(clicker).

Monitors also have a battery

test button which indicates

that the batteries are OK.


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RADIATION (SURVEY) MONITORS

The scale is a graduated

logarithmic scale.

In this case the range is

from zero to 1000 Sv

per our.

The dose rate at a

barrier for site

radiography must be

less than 7.5Sv/hr


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RESTRICTION OF ACCESS TO CONTROLLED AREAS

Because of the dangers

site radiography is

conducted in a restricted

(controlled) area.

e area s emarca e

by barriers and boards.

The area will be

monitored throughout to

ensure the dose levels

outside are safe, lessthan 7.5Sv/hr.


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RESTRICTION OF ACCESS TO CONTROLLED AREAS

On site radiography

often requires barriers

to be established at

different levels on a

,

level at which the workis being done.


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GAMMA ALARM

When the Alarm is switched on

radiation below threshold

7.5Sv/hr is indicated by a

amber flashing lamp.

Radiation above the threshold is

indicated by a red flashing

lamp.


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EMERGENCIES


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EMERGENCIES INVOLVING RADIOGRAPHY

Incidences involving damage to radiography equipment resulting in

loss of containment of the radioactive isotope are extremely rare. We

are not aware of any such incidents in recent history.

However, should such an instance occur the priority of the emergency

serv ces wou e or t e sa ety o t e pu c an t en property.

Because of the nature of the work requiring other personnel to be

excluded from an area, it is highly unlikely that other personnel would

be in the vicinity of the radiographic equipment.


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ACCIDENTS INVOLVING INDUSTRIALRADIOGRAPHY

Equipment is regularly maintained and Radiographers conduct weekly

check and before use , but from time to time things can go wrong.

Most accidents which happen are the result of equipment damage or

malfunction. However, such accidents result in the potential for higher

dose levels and not contamination or loss of containment.

Procedures called Contingency Plans are in place to deal with any

foreseeable incident.

Radiographers are trained to implement the Contingency Plan if an

incident occurs.

The law requires that radiographers receive adequate refresher training

and that Contingency Plans are rehearsed on an annual basis.


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EMERGENCIES AND CONTINGENCY PLANS

Following any incident, the approach to recovery of the equipment

would be dependant on the circumstances.

Any company involved in work with Ionising Radiation most have

contingency arrangements for dealing with emergencies.

These contingency arrangements involve;

Measuring dose levels and setting safe distances Access, restriction of personnel to the vicinity

Planning a course of action for recovery

Telling relevant people what the plan is and how we will proceed

Replacing the equipment into suitable container for removal

Calling for external assistance if required

Keeping the area clear of unauthorised personnel until it is safe


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THE PRINCIPLES OF PROTECTION FROM IONISINGRADIATION ARE

TIME, DISTANCE & SHIELDING

TIME, the shorter the length of time a person is exposed to a radiation

source, the smaller the dose received.

DISTANCE, the further a person is away from a radiation source, the

smaller the dose received. Radiation obeys the inverse square law

which, in simple terms means, if you double the distance away from

the source the dose will be reduced by a quarter.

SHIELDING, materials absorb radiation, by shielding people from the

source dose levels are significantly reduced.


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SITE INCIDENTS WHEN SOURCE IS IN USE

CONTINGENCY PLAN

If a fire alarm or toxic alarm sounds when working with a source on site, the first priority

is THE RADIOGRAPHERS OWN SAFETY

If the source can be returned to a container without danger then it SHOULD BE

If the operator can remove a container without danger then HE SHOULD

If the operator is in any doubt, the container should be left where it is, AT THE FIRST

OPPORTUNITY THE RADIOGRAPHER SHALL REPORT THE SITUATION TO

THE CONTROL ROOM OR RESPONSIBLE PERSON. MAKING SURE THAT FIRE

FIGHTERS OR RESCUE PERSONNEL ARE AWARE OF THE EXACT LOCATION

OF THE BARRIERS AND THE CONTAINER. THEY SHOULD GIVE AS MUCH

DETAIL AS THEY CAN REGARDING DOSE LEVELS IN THE AREA.

They shall offer any assistance or advice they can.

The radiographer should inform their RPS at the first available opportunity.

The radiographer should remain available in case additional information or assistance is

required.


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CONTAINERS DAMAGED BY FIRE OR COLLAPSE

CONTINGENCY PLAN

If a container is caught in a fire or structural collapse the radiographers initial

responsi ility is for, THEIR OWN SAFETY FIRST.

THEY SHOULD REMOVE THEMSELVES TO A PLACE OF SAFETY AND

INFORM THE APPROPRIATE PERSONNEL. They should make themselves available

to offer any assistance or advice they can.

They should inform their RPS at the first available opportunity.


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ISO:3999 SPECIFICATION FOR APPARATUS FORGAMMA RADIOGRAPHY

All radiography equipment is produced to the highest standards and

licensed in accordance to rigorous requirements, which includes fire

and impact resistance, also resistance to puncture.

Should the equipment be involved in a fire, it is unlikely that the

emergency services would be exposed to dangerous levels of radiation,

however it would be appropriate if monitoring was carried out where

practicable.


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ACCIDENT IN THE USA IN 1979

In California in 1979 a radioactive source holder had become detached

from its container, the radiography crew were unaware of this and the

source holder was left at site.

An unsuspecting worker had found it and put it in his pocket, it was

left there for about 45minutes.

,

the man noticed a burning sensation and reddening of the buttock.

After two days the man went to his doctor, who thought it was an

insect bite.

The burn got worse and after seventeen days the man was hospitalised.

After three days of questioning by the doctors the man recalled having

the object in his pocket, at this point the Doctors realised that he had a

radiation burn.


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About fifty days after

the incident a skin flap

was sewn over the

burn to close it.


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About six months

after the incident a

secondary burn had

developed away from

.


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A second skin flap

had been added 19

months after the

accident, but the

fully healed.


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Radiation Incident

February 20th, 1999


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Incident Synthesis

Location

Hydroelectric Construction Site in Yanango.

Distance from Lima: 300km (East)

District: San Romn De artment of Junn.

What Happened

A non-authorised person removed the screws of the security

lock to free the radioactive source of a Gammagraph.

No key is needed to remove the source, it can be done with a

screwdriver.


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Equipments Characteristics

Security

Lock

Type: SPEC T-2

Radionucleid: Ir192

Activity Max: 3.7 TBq


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Equipments Characteristics

With a screwdriver, the safety

lock can be removed to make the

source accessible


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Welder

- 4:00 pm: A worker (welder) finds the source of gammagraphy (192 Ir)abandoned in a water pipe. He puts it in the back pocket of his trousers.

- He works for six hours with the source in his pocket and his assistant nearby

Chronology

- 10:00 pm: He leaves work, takes a bus and travels home (he felt little pain in hisright leg). During his return, he travelled for 30 minutes with 15 people.

- He thinks that the red skin is due to an insect sting.

- His wife sat on the trousers for 10 minutes to feed their baby. Two children slept

nearby.

- 11:00 pm: The welder, takes the trousers off in the room.


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Operator

- 10:30 pm: The operator makes a gammagraphy. The radiation detector doesntdetect any readings. He assumes the equipment is not working well and stops to

have dinner.

Chronology

- 00:00 am: He enters the water pipe, checks the gammagraphy equipment and

finds no screws or radioactive source. They start looking for the source.

- 1:00 am: They find the welder in his house (February 21st). He comes out with

the source in his hands. The operator slaps the welders hand knocking the source to

the street and puts a stone to cover it.

- The source is recovered and secured in a container with iron walls 2 thick.


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What was done?

Initially, the welder was hospitalized in the Cancer Centre

of Lima.

Chronology

He was then sent to the Military Hospital Precy de ClaartGrave Burns Treatment Centre in France.

C


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Consequences

Severe Radiation Exposure To 1 Person and

Minor Exposure to 18 Other People

Effects on Leg

(13:00pm 2/21/99)

16 Days After

the incident

3/8/99

Effects on Leg

(70 days after the

incident 5/3/99)


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Consequences

Leg Amputation

(10/18/99)

Severe Infection

12/14/99


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