05 lecture_5_working proc norm ind rev 12

National Committee for the Certification of Radiation Protection Officer

RADIATION SAFETY IN INDUSTRY RADIATION SAFETY IN INDUSTRY INVOLVING NORM/ TENORMINVOLVING NORM/ TENORM


Introduction Introduction

Man is continuously exposed to ionizing radiation which originates from naturally occurring radiation.

Radioactive materials and man-made radiation sources are always present in his environment.

In some places background radiation contributes significantly to human annual radiation dose exposures.

Sometimes Naturally Occurring Radioactive Materials (norm) are technologically enhanced following extraction of other valuable minerals yielding TENORM or Technologically Enhanced Radioactive Materials (e.g. oil and gas industry and tin mining).


NORM are scattered in low concentration or abundance in various samples such as soil, sediment, air, water and living organisms.

Natural radiation originates from 3 types of sources:

Cosmic rays Cosmogenic radionuclides Primordial radionuclides

Sources of Radiation Sources of Radiation


Cosmic radiation:

Originate from the stars of outer space.

Consist of proton (~ 85 %), alpha particle (~ 14 %) and heavy nucleus (~ 1 %).

Primary cosmic rays interact with the upper atmosphere and produce secondary cosmic rays consisting of muon (~70%) and electron (~30%).

Cosmic rays contribute around 300 Sv of total natural radiation exposure.



Cosmogenic radionuclides:

Are radionuclides produced following interactions of cosmic rays with particles in the atmosphere.

Examples of cosmogenic radionuclides are C-14, H-3, N-15.



Primordial radionuclides:

Radionuclide that coexisted during the creation of earth.

Radionuclide have very long half life, i.e. t1/2 >108 years e.g. U-235, U-

238, Th-232, K-40 and Rb- 87.



Annual per Capita Dose



Examples of NORMS are:

Natural uranium consisting of U-238 (99.28%), U-235 (0.715%) and U-234 (0.005%)).

U-238 decay series consists of 14 radionuclide.

At secular equilibrium, total U-235 activity is 11 times higher than any of its progenies.

This series consists of 7 alpha emitters and 4 beta emitters and finish with a stable Pb-207 nuclide.

Naturally Occurring Radioactive Materials (NORM)



Radon (Ra-222) is a gaseous decay product of Ra-226 (from U-238 series).

Thoron (Rn-220) is a gaseous decay product of Ra-224 (from Th-232 series).

Actinium series does not play a significant role in industrial TENORM due to its very low presence (1/6 of U-238) in the natural environment.

If not subjected to chemical or physical separation, each of these series attains a state of secular radioactive equilibrium.

Technological enhancement of NORM as well as natural physical and chemical reactions often interferes with this balance.




Radionuclides in Uranium Mining




Radionuclides’ Half-Lives




Two primary non-series radionuclides that contribute to background dose are K-40 and Rb-87. Potassium-40:

• K-40 is a beta (87.3%) and gamma (10.67%) emitter and contributes to both internal and external doses.

• K-40 exists as a constant fraction of stable potassium (0.0117%).

• Its contribution to external dose varies depending on its concentration in rocks and soil.

• Average concentration K-40 is about 0.6 Bq/g (17 pCi/g) in crustal rock.

Non-Series Radionuclides Contribution to Background Radiation



Rubidium-87:• Ru-87 is a pure beta emitter and is found in crustal rock in

concentrations of about 0.07 Bq/g (2 pCi/g).

It is not an external hazard and is rarely considered in dose calculations.

The remainder of the non-series radionuclides has combinations of half-lives, isotopic abundances, and elemental abundances such that they have negligibly small specific activities and are not significant in background dose calculations.




Significant amounts are TENORM derived from tin mining, tin slag and amang processing activities.

TENORM is also found in waste of petroleum sludge, oil scale, material or contaminated apparatus or facilities.

Estimates suggest that up to 30 % of domestic oil and gas wells may produce some elevated TENORM contamination.

Uranium and thorium compounds are mostly insoluble in oil and gas and will remain in the underground reservoirs.

Radium and radium daughter are soluble in formation water and extracted with oil and gas.

Technologically Enhanced Radioactive Materials (TENORM)



Radionuclides of TENORM/NORM:

TENORM can be emitters of low and high LET radiation.

Hazards associated with different LET radiation may be divided based on the modes of exposures, i.e. external and internal:

• External exposure:o Hazards from gamma emitter radionuclide.o Actual exposure dose depends on the volume of

source, the distance between the worker and the source, the working hours and the shielding used.

• Internal exposure:o Exposure to radon (Rn-222) and thoron (Rn-220).o Rn-220 and Rn-222 are radioactive gases and pose

internal hazards if inhale.





These alpha emitters will be trapped in the inhalation system especially in the bifurcations in the lungs producing radiation “hot spots”.

• Thoron:o A daughter of Th-232 decay series, with t1/2 of 55 sec.o Upon decay, it too produces alpha emitters that pose

internal radiation hazard.• Radon:

o A daughter from the U-238 decay series, and with a half life of 3.8 days.

o Hazardous if inhale into the body because it will decay and produce more hazardous alpha emitter progenies e.g. Po-218, Pb-214, Bi-204 and Po-214.





Internal hazards may also be a consequence of ingestion of NORM or entry of NORM through other means such as cuts and open wounds

Surface contamination:• NORM found in coal ash, tin slag, amang mineral

or petroleum production processes may cause surface contamination of the apparatus/facilities and working area.

• Such contamination may cause internal and/or external radiation exposure.




Radium-226 is generally present in scales, and in higher concentrations than Ra-228.

Typically, Ra-226 in scales is in equilibrium with its progeny, but Ra-228 is not.

The nominal activity appears to be about three times greater for Ra-226 than for Ra-228.

Radionuclide in Oil and Gas Scales

Radionuclide in Oil and Gas Scales

Radionuclides Concentration, Bq/g (pCi/g)

Ra-226 13.3 (360)

Pb-210 13.3 (360)

Po-210 13.3 (360)

Ra-228 4.44 (120)

Th-228 4.44 (120)


Coal ash contains TENORM that requires proper management and disposal.

Coal contains naturally occurring uranium and thorium, coal ash may present a potential radiological risk to exposed individuals.

The degree of risk will depend on the physical and radiological properties of the ash.

The radioactivity of coal may vary over two orders of magnitude depending on the type of coal and the region from which it was mined.

The concentrations of U-238 and Th-232 in coal average about 0.022 and 0.018 Bq/g (0.6 and 0.5 pCi/g), respectively.

Radionuclide in Coal and Coal Ash





Radionuclides Concentration, Bq/g (pCi/g)

U-238 0.12 (3.3)

U-234 0.12 (3.3)

Th-230 0.085 (2.3)

Ra-226 0.14 (3.7)

Pb-210 0.25 (6.8)

Po-210 0.26 (7.0)

U-235 0.0037 (0.1)

Pa-231 0.0059 (0.16)

Ac-227 0.0059 (0.16)

Th-232 0.077 (2.1)

Ra-228 0.066 (1.8)

Th-228 0.19 (3.2)


• The best method of managing radiation hazard and risk in industries involved with NORM is through engineering control.

• Serious attempt must be made to reduce suspension of dust containing TENORM in the air, and the discharge into the effluent.

• The hierarchy of radiological hazard control is engineering design followed by management control and Personal Protection Equipment (PPE) should be considered last.

Radiation Risk Control Radiation Risk Control


Engineering Control


Administrative Control


One method of controlling TENORM hazards and risks is by classifying the working areas.

Classification of working areas involves engineering as well as administrative controls.

Engineering control refers to the design of such working areas to meet the classification requirements.

Administrative control refers to procedures and instructions.

Classification of Working Area Classification of Working Area


Working areas should be classified as clean, supervise or control areas.

Working area is classified as control area when: External Dose rate is > 7.5 µSv/hr Surface contamination > 7 Bq/cm2

Contamination of Suspended particles is > 1 x 10-2 Bq/m3

Working area is classified as supervise area when: External Dose rate is between 2.5 - 7.5 µSv/hr Surface contamination 2 - 7 Bq/cm2

Contamination of Suspended particles is between 3 x 10-3 - 1 x 10-1 Bq/m3

Classification of Working Area Classification of Working Area


Classification of Working Areas


Next best method of controlling radiation risk after elimination, is engineering control.

Safe work procedure is one method of administrative control.

A practical and appropriate safe working procedure is necessary to avoid or reduce the effects of external and internal radiation exposures from NORM/TENORM.

Radiation Control Radiation Control


The basic principle of external radiation protection (i.e. time, distance, and shielding) should be considered in all safe working procedures.

All safe working procedures must be clear, concise and easy to follow by the users.

Training on the use of procedures must be given.

Safe working procedures must be reviewed periodically to ensure its intended effectiveness and efficiencies.



Personal Protective Equipment (PPE) is last choice in radiation protection methods.

PPE is used to reduce radiological risk, i.e. the probability of exposure and/or the impact of any accidental radiation exposure.

PPE must be used in conjunction with other hazards and risks controls.

Examples of PPE that should be considered when working with NORM/TENORM include: Respirators: to reduce the inhalation of dust containing

radionuclide. Gloves and apron: to reduce contamination of the body. Goggles: to reduce contamination of the eyes.



Areas and personal dose exposure monitoring shall be conducted as prescribed according to the classification of the working areas.

Records of area and personal dose monitoring should be kept and maintained as required by the relevant authorities.

Radiation Monitoring Radiation Monitoring


Activities related to NORM/TENORM usually involve large quantities but low activity concentrations of radionuclides.

Amang processing produces large quantity of valuable minerals containing TENORM that are usually stored in open spaces and exposed to the elements (rain and wind).

Storage areas with radiation level exceeding the permissible limit should be isolated and classified as restricted or prohibited area.

Handling and Storage of NORM/TENORM



Guidelines for amang storage areas: The storage area should be far enough from the office, workers

quarters or residential area; If a close store room is used, it should be equipped with good

ventilation system; The storage area must be fenced and locked; The storage area must be clearly labeled with radiation

warning signs.

General transportation procedure within and outside premise: Follow instructions related to LSA-1 category.




Environmental surveillance/monitoring program:

Radiological Impact Assessment (RIA) is required and must be carried out at all stages of operations:

• Before Operation: to assess potential radiological risk to workers and the environment before operation begins.

• During Operation: to assess new radiological risk not considered during the planning stage or that may arise as a consequence of changes made during operation.

• After or Shut Down Operation: to asses radiological risk during shut down and return to normalcy operations.

RIA for area and personal monitoring should be part of the organization Radiation Safety Management System (RSMS).




Short Quiz


Thank You

05 lecture_5_working proc norm ind rev 12

Documents

total u

manmade radiation sources

decay series

primary cosmic rays

types of sources

sources of radiationannual

actinium series

secondary cosmic rays