ALARA IMPLEMENTATION AND KNOWLEDGE MANAGEMENT IN NUCLEAR POWER PLANTS

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International Journal of Advanced Research in Engineering and Technology
(IJARET)
Volume 6, Issue 8, Aug 2015, pp. 69-82, Article ID: IJARET_06_08_007
Available online at
http://www.iaeme.com/IJARET/issues.asp?JTypeIJARET&VType=6&IType=8
ISSN Print: 0976-6480 and ISSN Online: 0976-6499
© IAEME Publication
___________________________________________________________________________
ALARA IMPLEMENTATION AND
KNOWLEDGE MANAGEMENT IN
NUCLEAR POWER PLANTS
Vidhya Sivasailanathan
Health Physicist, Bharatiya Nabhikiya Vidyut Nigam Limited,
Department of Atomic Energy, Kalpakkam – 603 102. Tamil Nadu
India & Research Scholar, Amet University, Kanathur, Chennai
Prabhat Kumar
Distinguished Scientist, DAE & Former Chairman & Managing Director,
Bharatiya Nabhikiya Vidyut Nigam Limited,
Department of Atomic Energy, Kalpakkam – 603 102. Tamil Nadu. India & Research
Supervisor, Amet University, Kanathur, Chennai – 603 112. India
Dr. N. Manoharan
Director Research, AMET University, Chennai, India
K. Lingeswaran
Assistant Professor, Department of Electrical and Electronics Engineering,
Bharath University, Chennai, India
ABSTRACT
Radiation protection procedures are being followed in operating power
plants aiming at reduction of exposure to ionising radiation to the
occupational workers and keeping the radiation levels “As Low As
Reasonably Achievable (ALARA)”. The protection against radioactivity is
being envisaged in an operating plant depending upon activities that include
selection of the material used for the reactor components, decontamination of
contaminated equipment, maintenance or replacement of contaminated
component, radioactive waste transport etc., During maintenance of reactor
or other radioactive components the chances of spread of contamination is
high and therefore extensive exposure control measures have to be
implemented. Contamination is the presence of radioactive material where its
existence is undesired. The radiological protection practices in the nuclear
power plants have gained its impetus in the optimization of protection by
design of the reactor, ventilation scheme, shielding techniques, mock up for

Vidhya Sivasailanathan, Prabhat Kumar, Dr. N. Manoharan and K. Lingeswaran
undertaking special jobs, appropriate tooling procedures, proper time
management, adequate knowledge on hot spots, training, access control etc.,
The radiological surveillance is carried out and implemented by the health
physics personnel of the operating power plant. The paper brings out the
intelligent effort, effectiveness of design, procedures and discipline by plant
personnel and role of knowledge management in implementation of ALARA
practices and reduction of collective dose.
Key words: Ionising radiation, ALARA, radioactive waste transport,
contamination, de-contamination, radiation measuring equipment, procedures,
mock up, training.
Cite this Article: Vidhya Sivasailanathan, Prabhat Kumar, Dr. N. Manoharan
and K. Lingeswaran, Alara Implementation and Knowledge Management In
Nuclear Power Plants. International Journal of Advanced Research in
Engineering and Technology, 6(8), 2015, pp. 69-82.
http://www.iaeme.com/IJARET/issues.asp?JType=IJARET&VType=6&IType=8
Background
Mankind though has been exposed to natural radiation for past several million years,
the invention of X-ray, radioactive isotopes and their effects of human body and the
environment had immensely demanded the protection against radiation generated by
human activity to avoid the ill effects of radiation. Apart from natural radioactivity
arising from cosmic rays and terrestrial radiation, the radiation exposure is due to the
consequence of the fallout from weapon tests, exposure of radiation from nuclear
facilities and nuclear reactor operation and accidents, radioactive waste management,
transport, disposal of the radioactive waste arising from the use of radioactive
materials for different uses in agriculture, medical etc., The global experiences of
radiation handling and its effects are quite well combined and shared internationally
leading to a study analyzing the causes and effects of the ionizing radiation.
International Commission of Radiation Protection (ICRP) and Atomic
Energy Regulatory Board (AERB)
The investigators on radiation handling and its effects has received inputs from the
following groups to make a better analysis of what is acceptable dose to human body
which has no harmful effect.
 Survivors of Atom bomb – the casualties arised during Hiroshima and Nagasaki
 Radiologists – The group of doctors who have been unknowingly getting exposure
 Radium dial painters
 Personnel working in uranium mines
 Dwellers in high natural background radiation areas (Canada, Brazil, China, Kerala in
India)
The outcomes of the studies revealed the importance of the awareness to be
brought in handling of ionising radiation. The experts in radiation protection from all
over the countries of the world joined and the International Commission of Radiation
Protection (ICRP) was formed in the year 1920.
ICRP formulates the guidelines to make the radiation protection safety standards
wherever radiation has found its applications. Based on the biological effects of the
ionizing radiation, ICRP has recommended the threshold limit value for the

Alara Implementation and Knowledge Management In Nuclear Power Plants
occupational radiation workers and such safety standards are subject to review from
time to time. Better radiological protection methodologies, innovations in handling of
radiation, developing new technologies in radiation detection instruments etc., were
discussed by the ICRP and shared to the global community of the nuclear industry.
The ICRP, in its publication Number 60, discusses the basic requirements of the
radiation protection:
Justification of Practice, Optimisation of protection and Dose limits.
Justification of Practice
The justification of practice states that the use of radioactivity in any field in
which it is applied must have the justification of its use.
Optimization of Protection
The use of radioactive sources shall be optimized considering the radiation type
{(alpha (α), beta (β), gamma (γ) radiations, neutron)}, energies, activity range and
their isotopic and biological half lives*
, the physical or chemical form of the source
which would enable the protection practices in normal and abnormal conditions etc.,
Dose Limits
The radiation protection practices concentrate on four major areas of concern, which
include:
 Radiation safety of work place
 Radiation safety of the occupational workers
 Radiation safety of general public
 Impact on environment of radioactivity release
Rendering due consideration on the above factors, the ICRP has recommended the
dose limits to the occupational workers in any industry must be kept below 20mSv
(milli Sievert)**
per year or 100 mSv in any consecutive five years. The limit is
arrived at considering the maximum life time occupational dose as 1Sv (Sievert) for a
span of 50 working years. ICRP has also recommended the prescribed annual limit
for the public as 1mSv/ year. The female employees working in a nuclear industry,
while they are pregnant are not allowed to consume the threshold dose as an
occupational worker as the foetus is considered as the general public and the dose
limit permitted to the abdomen is 1mSv only.
Radiation Protection in India
The Constitution Order (1983) of AERB vide clause 2 (vii) entrusted the function of
prescribing acceptable limits of radiation exposure to occupational workers and
members of the public and approve the acceptable limits of environmental release of
radioactive substances to Atomic Energy Regulatory Board (AERB). The Atomic
Energy Regulatory Board (AERB), the regulators of our country, has adopted the
guidelines of the ICRP. Currently, AERB has the stipulation of threshold dose limit
as 20mSv per year for occupational radiation workers.

ALARA
The discipline of the radiation protection practices of any operating nuclear power
station is reckoned by the collective dose of the station. The collective dose is the
summation of the dose of the occupational radiation workers for a particular year. The
scenarios of the events occurred during the year, number of personnel involved in hot
spot jobs etc., are some of the factors which act as the scale of the best adoption of
radiation protection measures of the operating power plant. The purpose of the
collective dose is to compare the radiation protection efficiencies in various plants,
the technologies followed and protection options. Collective dose is not supposed to
be used as data for epidemiological risk assessment or for risk projections based on
epidemiology and for the prediction of cancer deaths due to trivial exposures to large
populations. The International Commission of Radiation Protection (ICRP) has not
recommended any threshold or limit value for the collective dose as the compliance of
collective dose limit would require reduction of radiation levels, working times etc.,
that are plant specific. Further to this, the radiological conditions of different plants
will show larger variation. Moreover, the basic level of protection is recommended
by ICRP which is accepted internationally, the responsibility of optimisation of dose
and dose management rests with the plant management and the respective national
regulatory authority.
As a general practice, the operating plant will prepare the dose budget for the year,
allocating the dose limits that can be permissible for planned activities during
operation and shut down phases of the reactor.
*
half life: The time taken by the radioactive nuclide to reduce its activity by half
of its total activity.
**Sievert: Unit of dose (a measure of the radiation received or absorbed by a
target) equivalent to energy of 1 J/Kg or 104
erg/gm that attempts to quantitatively
evaluate the effects of ionising radiation.
The maximum value of the apportioned dose value will be contributed by the
maintenance jobs carried out in the plant. The replacement of in core components,
replacement / maintenance of valves, the spillage of heavy water (in pressurized
heavy water reactors), the leakage of primary sodium circuit (in fast breeder reactors),
replacement of insulation wool etc., are some of the possible scenarios considered
during the preparation of dose budget.
Factors causing exposure in Nuclear Power Plants with special reference
to PFBR
Prototype Fast Breeder Reactor (PFBR) is located in the place where the multi units
of Department of Atomic Energy are already operational. Sodium is used as the
coolant and Argon is used as the cover gas in the prototype fast breeder reactor.
Being situated amidst multi operational units, it becomes mandatory, that the dose
release is apportioned among the plants in such a way that the permissible limit of the
dose value to the public shall not be exceeding the limits recommended by the
Regulators. The apportioned dose value of PFBR is 100 micro Sievert including both
air and water routes of dose release during normal operation of the reactor. There are
certain areas which are prone to create contamination and contribute to increase of
radioactivity levels exceeding normal limits.

Sources of radioactivity in Primary Coolant (Sodium) Activity in PFBR
 Sodium-24 (Na-24) produced by the reaction {Na-23 (n,γ) Na-24} in the core
region.
 Na-22 produced by the reaction Na-23 produced by the reaction {Na-23 (n,2n)
Na-22 }
 Active Corrosion particles and fission products.
Activity of Sodium-24
The saturation activity of the Sodium-24 in primary sodium is estimated to be
592MBq/ml. This activity is reached within two days of reactor operation and decays
with a half life of 15 hours. Bulk shielding is provided against Sodium-24 activity as
it is a gamma emitter. Due to its shorter half-life, Sodium-24 portion of the coolant
ceases to be of high radioactive concern within a few days after removal from the
reactor.
Activity of Sodium-22
The saturation activity of Na-22 in primary sodium is attained in ten years of reactor
operation and is estimated to be 28 kBq/cm3. This activity builds slowly with reactor
operation since its half-life is 2.6 years, but poses problem for maintenance on the
primary sodium circuit. Sodium-22 is a positron emitter.
Corrosion and Fission Products
The radioactive corrosion products formed in the primary sodium are: Chromium-51,
Manganese-54, (Iron) Fe-59, Cobalt-58 and Cobalt-60. The specific activity in the
coolant for important corrosion products are estimated based on the design values.
About 90% of Mn-54 is deposited on Intermediate Heat Exchanger (IHX) and this
poses an exposure problem during handling and also requires elaborate shielding
arrangement.
Sources of activity in Cover Gas Circuit
Argon is used as the cover gas in the fast breeder reactor. The reactor is operated with
limited gas leakers. Four fuel pin failure operation is considered for design. The
cover gas during normal operation may contain fission gas activities due to four fuel
pin failures. Hence, even during normal operation, activity in cover gas is mainly due
to release of fission gases from the pins. The Argon-41 activity in cover gas is due to
the activation of potassium present as impurity in sodium. During normal operation,
the following gaseous activities are released to the cover gas from sodium.
 Potassium 41 undergoes n,p reaction; produces Argon 41. (half life of is
1.8hours) K41(n,p)Ar41
 Sodium 23 undergoes n,p reaction; produces Sodium 24 (half life is 37 sec) Na23
(n,p) Na24
 Calcium 40 undergoes n,α reaction; produces Argon 37 (half life is 35 days) Ca40
(n,α) Ar37
Decontamination of surface of floor or equipment
The presence of radioactive material where its existence is not desired is known as
contamination. The process of elimination of contamination is decontamination. The
equipment which are used in the primary sodium circuit or directly used or present

inside the core component, the tools that are used in handling such active equipment
etc., will have higher probability of getting contaminated. If the loose contamination
is present on the surface, it can be washed off with any decontaminating agents. If the
fixed contamination is present on the surface of the equipment or on the floor, then
the method of decontamination will vary. Sometimes decontamination is carried out
by chipping off the particular portion of the equipment and repaint it. If there is a
possibility to keep the floors also be painted and maintained in the same way, the
painted portion can be chipped off to clear the contamination and the surface can be
repainted.
Maintenance Jobs
The radioactive equipment which require replacement or repairing jobs will attract the
radiation protection measures to achieve the radioactive limits As Low As Reasonably
Achievable (ALARA). The components that are used inside the core involved in the
fission reaction have the higher probability of getting contaminated with the
radioactive isotopes of Cobalt-60, Sodium-24 etc., Inclined Fuel Transfer Machine
(IFTM), Flasks, Intermediate Heat Exchanger (IHX), Pumps, Fuel sub assembly
replacement, failed fuel assembly detection etc., are some of the equipment that are
contaminated during reactor operation. While taking up the maintenance of these
equipment, care need to be taken for permissible limit of radioactivity release and
avoidance of contamination spread to the surrounding place. The shielding
arrangements, design of entry and exit for men and equipment, washing facility for
decontamination, drainage for active liquid effluent to the tanks etc., will help
bringing down the activity levels to a great extent. The preservation of such a large in-
core components even after decontamination of its surface will continue to act as the
radioactive source emitting ionising radiation. Adequate shielding techniques,
restricted men and equipment entry need to be followed for exposure reduction.
In Service Inspection
In operating plants, it is required to carry out the inspection of working mechanism of
the equipment while the reactor is in operation. This is important for health physicists
to control radiation exposure to plant personnel during such inspection campaigns and
exercise adequate radiation protection measures.
During shutdown, extensive inservice inspection is carried out wherever field is
high and approach for manual measurement / supervision is difficult. Robotic vehicle
is an alternative tool to be used for in service inspection. Based on the data acquired
by in service inspection, the healthiness of the equipment is ensured. The space
between safety vessel and main vessel is filled with Nitrogen gas. This space is used
for ISI vehicle to be taken to various zone. The vehicle has also maintained pressure /
grip on the walls of Main Vessel and Safety Vessel and may bring out certain
contamination when it is withdrawn out of the annulus.
Routine walk through
The walk through survey to monitor the radioactivity levels in various zones is also a
cause for radiation exposure. Spending of minimum time in noting down the reading
and proper idea of location to be surveyed help in reduction of exposure. This is a part
of good practice of reducing the exposure to ionising radiation.

House Keeping
House keeping is another activity which helps to keep the area contamination free and
reduces exposure. But while carrying out house keeping, the usage of cleaning liquid,
mop sticks, the disposal of used liquid, clothing etc., are the factors which may
contribute for exposure and spread of contamination. The proper disposal of such
cleaning materials is required to be done with due care or otherwise this will carry
contamination and spread. The frequent and perfect housekeeping are observed as a
good practice contributing for dose reduction in nuclear power plants.
Calibration of radiation monitoring equipment
Calibration of radiation monitoring equipment is a periodic event to check the
healthiness of the radioactive instruments. The instrument is calibrated using a known
radioactive source of desired strength as per the requirement. While handling the
source, the precautionary measures like using the source with tongs, keeping the
source in its earmarked container, usage of dosimeters, log of readings of background
and during use of source etc., need to be ritually maintained as it is the direct cause of
exposure to the user. It is important to note that if the calibration takes the exposure
time limit of the order of several minutes, then it is advisable to quarantine the source
i.e., to keep the radioactive source open for enabling the calibration and leave the
place till the earmarked time gets over. This is one of the best possible ways to reduce
exposure while handling a known radioactive source.
Health Physics survey
Survey of radioactivity levels in and around the plant area will be done by Health
Physics officials shiftwise. There are possibilities of exposure to dose during such
surveillance activities. It is advised to make the survey quicker and leave the high
active area in shortest possible time to reduce the exposure.
Stack measurements
Stack is the place where the ventilation system ends to release the gaseous effluents to
the environment from the plant having passed through various filters. The sample line
will be provided to take the swipe sample of the gaseous effluent or the airborne
activity. While taking sample the active effluent line will be handled by the person
who is taking the sample. Though the activity is supposed to be at minimum value, it
contributes to some extent in dose count. Knowledge on the sampling point and
sampling procedures would help in spending lesser time while taking swipe sample at
the stack room.
Transportation of radioactive material
Transportation of radioactive material is an important activity in every nuclear
facility. If any component that has been used inside the reactor core which is certainly
contaminated to an appreciable extent, the radiological levels at the surface of the
material and at 1metre distance are measured before taking up transportation. Further,
it has to be ensured that the component does not have any loose contamination on its
surface that could dislodge and contaminate the environment, ground, air, water
during transit. If the values fall within the permissible limits as recommended by the
regulatory authority, then only the material will be allowed to be transported from the
plant to the waste management facility. However, the removal of the component,
decontamination of surface of the equipment and floor, continuous monitoring of the

radioactive levels, packing etc., contribute widely to exposure to radiation and
radioactive dose.
Repair activities and on power entry to shut down accessible areas
The repair of the core components and associated smaller activities also contribute as
a prime factor of causing exposure. Some of the repair activities are required to be
done when the reactor is in operation. There are certain areas that could become
accessible only during shut down phase of the reactor. Whenever, there requires a
monitoring / maintenance job in such shut down accessible areas, the reactor ‘on
power’ entry needs to be done by the operations or maintenance crew by seeking
special permits. Such maintenance activities need special training, adequate
knowledge about the system and mock up to contain the dose / exposure to the
working crew.
Sodium Sampling and maintenance of cold trap
The sodium that is used as coolant in PFBR reactor will be analysed for its purity and
presence of isotopic sodium. The sodium in the primary circuit is thoroughly
contaminated and the sample of sodium taken for analysis is a source of radioactivity.
The spillage of contaminated or the radioactive sodium is considered as the source of
radioactivity. The cold trap catches the impurities of sodium and contains the sodium
in aerosol form and associated radioisotopes. The maintenance of the cold trap
requires special arrangement and waste management yard to dispose it properly to the
environment. The sodium aerosol is the mixture of sodium oxide and sodium
hydroxide. Sodium aerosol is treated with acid in the presence of a medium to split it
into sodium chloride and water. The treated products are then suitably disposed off to
the environment. The process will be done at the isolated location where there will be
a less access of people. Handling of sodium requires special training and precautions
need to be taken to avoid sodium catching fire and extinguishing the same in case of
any incident.
Waste disposal
The waste disposal is an important contributor of exposure. The uncared throwing off
of used cotton, gloves etc., will form the source of contamination spread and
radioactive source. This may happen because of the wrong habitual acts of the
personnel. The discipline of disposal of used items in the earmarked bins would help
reduce such kind of exposure and contamination spread. The Waste in a nuclear
power plant does not only mean the spent subassembly waste; it denotes the
accessories that are contaminated and has no further use. The waste in solid, liquid
and gaseous forms are properly collected, treated and disposed off as per the
recommendations of the regulatory authority.
Cover gas sampling & analysis
As in the case of sodium discussed above, Argon which is used as the cover gas in the
Prototype Fast Breeder Reactor (PFBR) also needs to be analysed for checking of
activity levels and purity of Argon gas. The cover gas sample will be collected using
a sampling point and analysed in the chemical lab.

Good Practices by PFBR team in bringing down the exposure rates
Though there are various factors which contribute for contamination as well as cause
exposure to ionising radiation, there are good practices that can help us avoid spread
of contamination and reduce the levels of radioactivity. Some of the best and time
tested practices which are being adopted in PFBR are discussed below:
Mock up
The work in radiation field is stressful and occasionally in non-conducive working
environment; in difficult postures in humid and warm surroundings. Unless, the
entire activity to be done for conduct of work in radiation is rehearsed on a mock up,
the possibility of excess radiation dose consumption is unavoidable. Mock up should
be the actual simulation of working environment, physical restriction, space, objects,
heights etc., for actual job and the conditions like heat, humidity, light etc., The tools,
methods, procedures of every individual involved with the job, sequence of activity
and time need to be computed on mock up and review done whether the time /
exposure could be reduced by improving tools, sequence methods etc.,
We have in PFBR critical jobs like
 Replacement of Control and Safety Rod Drive Mechanism (CSRDM) /Diverse
Safety Rod Drive Mechanism (DSRDM)
 Repair and maintenance of Intermediate Heat Exchanger (IHX)
 Replacement of Pumps, transfer arm, inclined fuel transfer machine functional
checks
 In Service Inspection(ISI) of piping, supports, vessels etc.,
These jobs are in different areas requiring different techniques that need to be
rehearsed or mock-up.
The mock-up of creation of same scenario in a safe environment will help
understand the real situation and the precautions which need to be taken in the actual
case. The use of radiation protection equipment, the demand for using respirator,
shielding techniques, the time limit permissible for carrying out the job, the
requirement of tool and proper use of them, the exact requirement of man power to
accomplish the task etc., shall be worked out for better performance in the real
scenario.
Training procedures
Training is an unbeatable tool to the successful accomplishment of any kind of job;
jobs in radioactive areas are also of no exception. The training simulates and creates
awareness of the time, distance and shielding concept and helps in exposure
reduction; it suggests the importance of the quality of work need to be done. Training
gives the full fledged information about the job to be undertaken, associated risk
involved, the protection measures etc., The training once given to the occupational
workers need to be refreshed at periodic intervals of time, for better implementation
of radiation protection practices.
Qualification of tools and gadgets
Tools constitute the important role in repair and maintenance jobs. The selection of
best quality tool reduces the burden of job into half. The combination of radiological
survey instrument and contamination check instrument into a same device would
enable the surveillance easier and reduces the manpower to carry the instrument to the

survey location. The lengthy probed instrument for measuring radiation levels at high
active areas (teletector has 4 metre length probe) helps reducing the dose exposure to
the individual to a considerable extent. The instrument like portable radionuclide
identifier can be useful in the detection of presence of radionuclide in the high active
area without taking a sample and bringing to lab for analysis. This saves the time of
the analysis, manpower to take sampling and to avoid associated spread of
contamination if any.
Good House keeping
The house keeping at regular intervals would help ensure the absence of
contamination on the floor. The regular practice of house keeping also helps identify
the presence of any unwanted source of material on the floor or in the accessible
areas. The clear area is always a healthy sign and avoidance of contamination spread.
Access control
The limited entry of manpower in the high active areas helps reduce the exposure
level to a group of individuals to a maximum extent. It is a good practice that no
onlookers are permitted while carrying out the high active jobs. This would avoid
unnecessary dose exposure. Optimised man power for any kind of job will contribute
to the lesser magnitude of the collective dose of the station.
Rubber station
Rubber station is useful in avoiding contamination spread while moving from high
active zone to low active zone. The personnel would change his shoes, gloves, head
cap, protective suits etc., in the high active zones before crossing to low active zones.
The rubber stations will be made available at the interzonal points, preferably from
zone -3 to zone -2 areas. The rubber stations are created at places wherever the job is
prone to create contamination as a preventive measure. This will be placed as a
temporary arrangement also at places where the high active components are being
brought and kept for maintenance jobs.
Physical monitoring
The physical monitoring of the radiation instruments while checking up of the
readings and its calibration status etc., would help in the maintenance of the
instruments in a healthy state. The healthiness of the instruments help in identifying
the correct radiological levels in and around the plant area. The installed radiation
monitors at different access points to help monitor the radiological data at the main
control room; whereas the healthiness of all such installed monitor need to be
calibrated periodically. The monitors shall be calibrated with a known radioactive
source.
Online surveymetry
The connectivity of the area monitoring as signals in the system would be the best
practice to know the radiological levels. One need not go to the radioactive area for
noting down the radiological levels whereas the signals that are connected from the
area monitor to the control room will indicate the signals through the mimics installed
in the main control room as per the requirement. This engineered feature enables to
reduced dose exposure to considerable extent to the monitoring personnel.

Camera
Fixing of cameras in high active areas, where personnel cannot make an entry when
the reactor power is on, serve the purpose of monitoring the radiological events
happening at the particular location. The output signals that can be viewed at the
control room enhances a better feedback on the operation /actions. Thus cameras are
helpful in reducing the exposure. Extending the cable from the active / work area /
component or from the detector and keeping the monitor which displays the data in
the low radioactive zone is another good practice to bring down the exposure levels.
Administrative Control
Maintenance of log of events, record keeping, calibration status of the equipment,
statistics of the personnel entry and exit, the radiological levels in the plant shift wise,
sharing of past experiences, conducting workshops, seminars, refresher training, full
fledged training centre, models of equipment, issue of work permit, dose management
system etc., are some of the practices that can establish a good discipline in adoption
of knowledge management in bringing the radiation exposure levels to an important
tool ALARA.
Clarity in communication
Communication is considered as the most appropriate tool in carrying out the specific
activities at all times. When it is correctly used would bring enormous benefit to the
plant management. In nuclear industry, communication is felt most important during
pre job briefing itself. Whenever job is allotted to a person by the system engineer,
while explaining the job to the worker, it needs to be ensured that the worker has
understood the job hazards and precautions need to be taken about the job. He is not
supposed to be simply a listener of what he has been told. Rather he has to respond to
the instructions. He is supposed to repeat the proceedings of job and it should be
confirmed back by the system engineer. Thus communication is the best tool for
proper understanding and correct execution of the job. Clarity in communication helps
avoid confusion in the workspot. While working in field they must know what has to
be done. For example, if the system engineer is giving an instruction to the
maintenance person to close the valve C16 in the A8 row; he has to get it confirmed
back by the worker for the correct understanding of the location that he should not do
mistake with A8 valve in C16 row.
Documentation
Documentation is the process of recording and compilation of events that have
occurred in every stage of activity in an organization. In a nuclear power plant, the
first experience of equipment erection is vital and documentation comprising of these
have to be recorded. The replacement / maintenance experience before the reactor is
made operational is also essential part of documentation. The base line inspection
also forms part of documentation. The component manufacturing history, Design
Change Note (DCN), Design Construction Request (DCR) and important instructions
constitute part of documents. Before taking up any job in high active area, this
documentation needs to be referred and then only personnel need to be permitted to
take up the job at such high active areas. Recording of events for every job will
constitute a part of documentation. The record will not only ensure the day to day
happenings but it serves as the supporting document of justification of various
practices of dose computation. It acts as the tool to avoid similar mistakes in future in

related jobs. The documentation gives the clear idea of what has happened and how it
can be improved. It stands as the evidence of better practices to be followed next
time. It serves as the system indicator whether there is a need of improvement in the
practices and procedures. Documentation needs complete vigil on the system and
requires periodic updation of its contents. The improvement made because of the
experience gained or lessons learnt add weightage to the effective maintenance of
documentation. It should be the centralized information provider of all activities of a
nuclear power plant.
Trend analysis
The comparison of the nature of the job expected to be arisen, methods to handle the
emergency situations, maintenance of log of events, record keeping, documentation of
the procedures and practices, sharing of experiences, application of lessons learnt
from previous experiences, training, repeated mock ups, perfect tooling methods,
ensuring clarity in communication prior, during and after execution of jobs, forcing
the occupational workers to follow the rules, best administrative procedures like
access control, motivation of workers for proper understanding of the work nature,
issue of work permit, inspection of equipment and records, periodic audit of work
procedures etc., are some of the performance indicators to decide the level of better
ALARA practice. The comparison of the resultant dose from previous year to the
current year is the best gauge to analyse the trend. The ‘cumulative dose’ which is
diminishing slowly from previous years will reflect the trend in maintaining the best
radiation protection measures. The dose record data experienced in the past years to
the current year helps derive the trend analysis of ALARA effectiveness of the
operating nuclear power plant.
Corrective measures
The knowledge gained from the past experiences of handling radioactive jobs will act
as the guide on further measures in bringing down the exposure. This occurs during
both the operation phase and shut down phase of the nuclear reactor. The
maintenance jobs would be carried out in a reactor when it is in operation and in shut
down condition. The reactor ‘on power’ entry in areas that are normally accessible
only during shut down, prompt identification and replacement of failed fuel are some
of the challenging jobs that require the proper feedback from previous experiences.
The maintenance jobs when the reactor is in operation requires the specific conditions
of the practices to be adopted as the chances of exposure is high. Though the high
radioactive components are adequately shielded, the distance from the active source
and completion of jobs in lesser time would be the best means of reduction of
exposure. The corrective measures that are experienced in every high active jobs
need to be noted down for future reference and guidance. The techniques of remote
tooling, long probed equipment, surveillance using cameras, in service inspection by
robotics, fixing permanent approach platforms to work in higher elevation
maintenance jobs, pre job planning, post job critique etc., provide the corrective
measures to be adopted wherever high exposure jobs is expected to be handled.
Role of HP in implementing ALARA
As a general notion, ALARA is the joint responsibility of everyone working in the
radioactive industry. People need to be practiced to be disciplined in adhering to the
procedures to avoid exposure, as radiation is non-sensory and impartial to people who
get exposed. The procedures should be followed in normal walk through as much as

during maintenance activities. It is the part of Health Physicist to keep a strict vigil
on jobs and enforce where the job can be done with remote tools / procedures. The
camera can be fixed by extending the cable in the low radioactive zone and the
activities can be monitored. The high active areas which require the continuous
monitoring and maintenance jobs can be provided with lead curtains; as a part of
shielding requirement. As a health physicist, I feel that continuous, good and
frequent house keeping measures, remote monitoring of high active jobs, use of
personal protective equipment like gloves, provision of rubber stations, use of
ventilated plastic suits etc., to avoid the dose exposure to extremities and the air borne
contaminants, documentation of jobs, improving the existing documentation based on
the experience and the lessons learnt in execution of jobs with less dose exposure
would help achieve the exposure levels As Low As Reasonably Achievable (ALARA)
to a large extent.
Concluding remarks
ALARA is the widely accepted practice among the best tools in the nuclear industry
to bring down occupational exposure to a considerable extent. The past observations
and the methods of handling with hot spot areas in an operating power plant widely
help in deriving the best ALARA practices to avoid over exposure in the future plant
life. ALARA demands the technical expertise, adequate knowledge on the event to be
managed, the importance of mock-up, training, and documentation. Apart from the
design features of the reactor, ventilation scheme of the reactor, material selection,
usage of high quality filters, isolation of reactor containment building, online
monitoring of the radioactivity levels, dose records and management system, issue of
work permit, adoption of corrective measures that are learnt from previous
experiences etc., the administrative procedures like access control, training and mock-
up also play an important role in ALARA besides knowledge management.
All jobs narrated in the paper require definite exposure reduction practices
through knowledge management. Effective ALARA programs must include the
participation of all facility workgroups, management support, teamwork and strong
leadership. The development and sustainability of effective ALARA programs require
the establishment and monitoring of goals, rewarding the successful achievement of
those goals and incorporating lessons learned from tasks that fail to meet their goals.
ACKNOWLEDGEMENT
The author sincerely acknowledges the efforts and the guidance rendered by her
supervisor which has helped in analysing the dose reduction techniques during
construction stage and the design of the reactor, construction features, management
tools and administrative controls that shall reflect in the form of dose reduction
measures.
REFERENCES
[1] International Commission on Radiation Protection-ICRP 60, Pergamon Press,
Oxford (1990).
[2] International Basic Safety Standards for Radiation protection against ionizing
radiation and for the safety radioactive sources, IAEA SS No.115, 1996
[3] Activities of AERB, Report No.9 of 2012-2013
[4] The Preliminary Safety Analysis Report of Prototype Fast Breeder Reactor

[5] Radiation exposure controls, reports & exposures during the radiographic
examination of equipment and piping during construction stage of PFBR
[6] Radiometric methods, mock ups and controls exercised during radiometric
examination of concrete cells, Roof slab block and Lead Flasks in PFBR.
[7] Done J.Tashevski, Risto V. Filkoski and Igor K. Shesho. Optimisation of
Binary Cogenerative Thermal Power Plants with Solid Oxide Fuel Cells on
Natural Gas, International Journal of Mechanical Engineering &
Technology, 3(2), 2012, pp. 633 – 642.
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[10] Wani Ahmad, MSK Prasad, Bhat Javed, V Thangapandian. Coal Accident
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