nuclear energy instrumentation

8/4/2019 Nuclear Energy INSTRUMENTATION

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INSTRUMENTATION &

CONTROL OF

NUCLEAR POWER PLANT


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Objective

The primary objective of this report is toinform NRC staff of emerging I&Ctechnologies and applications that are

being studied or developed for use in bothoperating and new NPPs

The focus of this report is the review of

seven technology areas:


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(1) Sensors and measurement systems

(2) Communications & networking media

(3) Testing and calibration(4) Computational platforms

(5) Human-system interactions

(6) High-integrity software(7) I&C architectures in new plants


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INTRODUCTION-

Nuclear power plants rely on instrumentation and control(I&C) systems for monitoring, control, and protection.

During their extensive history, analog I&C systems haveperformed intended monitoring and control functionssatisfactorily.

Although there have been some design problems, such asinaccurate design specifications conditions, the primaryconcern with the extended use of analog systems e.g.mechanical failures, environmental degradation.


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Experience from operation can be used to improve existing

power plants as well as the design of new ones.

It influences the design of I&C in different areas, the most

important of which are:

Increasing plant availability by various means.

Identifying new functions for the plant computer systemsto support the operators.

Testing and calibration during power operation. Human error.

New technology.


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IMPORTANCE OF INSTRUMENTATION AND CONTROL-

The instrumentation and control (I&C) systems of a nuclear power plant(NPP) have three major roles

1) Firstly, they are the eyes and ears of the

operator. If properly planned, designed,constructed and maintained, they provide

accurate and appropriate information and permitjudicious action during both normal andabnormal operation.


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2) Secondly, under normal operatingconditions they provide automatic control,both of the main plant and of many

ancillary systems.This allows the operator time to observe

plant behaviour and monitor what is

happening so that the right correctiveaction can be taken quickly, if required


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3) Thirdly, the I&C safety systems protectthe plant from the consequences of anymistakes which the operator or the

automatic control system may make.Under abnormal conditions they providerapid automatic action to protect both the

plant and the environment.


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Overview

We will start with a brief introduction, thenextraction and processing of uranium. Wethen discuss the distribution of uranium to

enrichment facilities, and the enrichmentprocess. This is followed by a moredetailed explanation of nuclear uses for

weapons and electricity production &control of nuclear power plant.


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Brief History

Nuclear energy was first discovered in 1934 byEnrico Fermi. The first nuclear bombs were builtin 1945 as a result of the infamous ManhattanProject. The first plutonium bomb, code-named

Trinity, was detonated on July 16, 1945 in NewMexico. On August 6th 1945 the first uraniumbomb was detonated over Hiroshima. Threedays later a plutonium bomb was dropped on

Nagasaki. There is over 200,000 deathsassociated with these detonations. Electricitywasnt produced with nuclear energy until 1951.

Source: The Green Peace Book of the Nuclear Age by JohnMay


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Radiation

Radiation is the result of an unstable atomdecaying to reach a stable state. Half-life is theaverage amount of time it takes for a sample ofa particular element to decay half way.

Natural radiation is everywhereour bodies,rocks, water, sunshine. However, manmaderadiation is much stronger. There are currently37 radioactive elements in the periodic table26 of them are manmade and include plutonium.

Source: http://theodoregray.com/PeriodicTable/index.html
http://theodoregray.com/PeriodicTable/index.htmlhttp://theodoregray.com/PeriodicTable/index.html


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Fukushima Daini power plant


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Types of Radiation

There are several different kinds of radiation: alpharadiation, beta radiation, gamma rays, and neutronemission. Alpha radiation is the release of two protonsand two neutrons, and normally occurs in fission ofheavier elements. Alpha particles are heavy and cannot

penetrate human skin. Beta particles can penetrate theskin, but not light metals. Gamma rays is a type ofelectromagnetic radiation which is left over after alphaand beta are released and include X-rays, light, radiowaves, and microwaves.

Source: The Green Peace Book of the Nuclear Age by JohnMay


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Penetration of Radioactive particles

Source: http://www.ratical.org/radiation/NRBE/NRBE3.html
http://www.ratical.org/radiation/NRBE/NRBE3.htmlhttp://www.ratical.org/radiation/NRBE/NRBE3.html


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Uranium

Uranium is usually mined similarly to otherheavy metalsunder ground or in open pitsbut other methods can also be used. After theuranium is mined it is milled near the excavation

site using leaching processes.The mining process explained here is a

combination of two of major mines in Australia.Then we will look at the Navajo uranium minerswho were some of the first uranium miners.Next I will explain some of the other communityand environmental impacts associated with themining processes.


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Mining

Uranium ore is usuallylocated aerially; coresamples are then drilledand analyzed bygeologists. The uranium

ore is extracted by means of drilling and blasting.Mines can be in either open pits or underground.

Uranium concentrations are a small percentageof the rock that is mined, so tons of tailingswaste are generated by the mining process.

Sources: http://www.anawa.org.au/mining/index.html and

http://www.energyres.com.au/ranger/mill_diagram.pdf and http://www.world-nuclear.org/education/mining.htm
http://www.anawa.org.au/mining/index.htmlhttp://www.energyres.com.au/ranger/mill_diagram.pdfhttp://www.world-nuclear.org/education/mining.htmhttp://www.world-nuclear.org/education/mining.htmhttp://www.world-nuclear.org/education/mining.htmhttp://www.world-nuclear.org/education/mining.htmhttp://www.world-nuclear.org/education/mining.htmhttp://www.energyres.com.au/ranger/mill_diagram.pdfhttp://www.anawa.org.au/mining/index.html


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Milling & Leaching

The ore is first crushed into smaller bits,then it is sent through a ball mill where itis crushed into a fine powder. The fine oreis mixed with water, thickened, and then

put into leaching tanks where 90% of theuranium ore is leached out with sulfuricacid. Next the uranium ore is separatedfrom the depleted ore in a multistage

washing system. The depleted ore isthen neutralized with lime and put into atailings repository.

Sources: http://www.anawa.org.au/mining/index.html and

http://www.energyres.com.au/ranger/mill_diagram.pdf
http://www.anawa.org.au/mining/index.htmlhttp://www.energyres.com.au/ranger/mill_diagram.pdfhttp://www.energyres.com.au/ranger/mill_diagram.pdfhttp://www.anawa.org.au/mining/index.html


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Mining Leaders

Australia and Canada are currently the biggestUranium miners. The aforementioned processthat takes place in Australia is exported becauseAustralia does not have a nuclear energyprogram.

The mining in Australian is primarily open pit, whilethe mining in Canada is mostly underground.Following is two chartsone is the majoruranium producing countries, the other is of themajor corporations that actually do the mining.

Source: http://www.antenna.nl/wise/uranium/uwai.html
http://www.antenna.nl/wise/uranium/uwai.htmlhttp://www.antenna.nl/wise/uranium/uwai.html


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Production in 2000

Canada 10,682Australia 7,578

Niger 2,895

Namibia 2,714

Uzbekistan 2,350

Russia (est) 2,000

Kazakhstan 1,752

USA 1,456

South Africa 878

China (est) 500

Ukraine (est) 500

Czech Republic 500

India (est) 200

France 319

others 422

Total world 34,746

company tonnes U

Cameco 7218

Cogema 6643WMC 3693

ERA 3564

Navoi 2400

Rossing 2239

KazAtomProm 2018Priargunsky 2000

Source: http://www.world-nuclear.org/search/index.htm
http://www.world-nuclear.org/search/index.htmhttp://www.world-nuclear.org/search/index.htmhttp://www.world-nuclear.org/search/index.htmhttp://www.world-nuclear.org/search/index.htm


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Reactor Types

PRWPressurized Water Reactordoes not boil, but uses the pressureof the water to heat a secondary source of water that generateselectricity. Most popular (accounts for 65% of reactors world wide).Considered a light water reactor.

BRWBoiling Water Reactorboils water (coolant) that makes steam toturn turbines. Conducive to internal contamination. Also considered a

light water reactor.RBMKGraphite-moderated pressure tube boiling-water reactor similar

to BWR but uses graphite and oxygen. Complex and difficult toexamine.

CANDUCanadian Deuterium UraniumDoesnt use enriched fuel. Haslots of tubes and internal contamination issues.

AGRAdvanced Gas-cooledalso cooled with carbon dioxide or helium.Uses enriched uranium. (UK).

FastBreederhigh temperature gas reactor. Uses U235, U238, andPlutonium 239. Very dangerous because it uses liquid sodium in theprimary circuit and in inflammable with air and explosive with water.

Source: www.world-nuclear.org/
http://www.world-nuclear.org/http://www.world-nuclear.org/http://www.world-nuclear.org/http://www.world-nuclear.org/


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I&C CONTROL SYSTEM

sensors and measurement systems-

Focus area, the key regulatory issues include

response time requirements accuracy of the

instrumentation which can enable applicantsto argue for reduced operating margins.

These are mainly optical fiber based sensors.

Use of sensors with inherent drift-free

characteristics we can eliminate the need for

calibration.


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Institute of Electrical & ElectronicsEngineers

(IEEE) Std. 338-2006, IEEE StandardCriteria

for Periodic Surveillance Testing of Nuclear

Power Generating Station Safety Systems,

provides criteria for the periodic testing of

nuclear power generating station safety

systems


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For the communication and

networking focus area-

1) Boosting data transmission speeds.

2) Developing more robust protocols

3) Error correction spectrum

4) Techniques (direct sequence, frequencyhopping, time hopped).


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Human error-The number of human errors in NPP operation is likely to

increase because: As plants become older, more manual maintenance is

required. Experienced operators, some of whom may have

worked in the control room since commissioning, arebeing replaced. It include-

Organizational improvements;

Training improvements; Modification of existing equipment; Installation of new equipment.


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Testing and calibration-

During baseload operation, manual testing of I&C

and calibration of sensors can be extensive.

However, because of the possibility of human

Error in manual testing and calibration has two

disadvantages:

Spurious scrams may occur during the testing ofprotection systems;

Temporary bypasses may not be restored after testing


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For these reasons, on-line and automatic testing is being

introduced more and more in new systems as well as by

backfitting. Such automated testing equipment can

be rather complicated, with the result that protection

systems on which it is fitted areless simple duringoperation.

This can be done by using better component quality &

increasing the mean time between failures (MTBF) or byimproving fault tolerance

by better design.


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Plant availability-

Improving plant availability and Reducing stress byreducing

the number of reactor scrams and turbine trips has been animportant endeavour and the study of scrams and trips has

often led to Design improvements in I&C.

In the early years of plant operation, the contribution ofspurious scrams from I&C itself can be relatively high and

can be reduced by modifications such as:


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(a) Making the protection system more tolerant totransients which are not significant to safety, e.g.by increasing its resistance to electromagneticinterference.

(b) Increasing the quality and redundancy ofimportant control systems in the plant.

Examples - systems for feedwater control,

turbine control, reactor pressure control andcontrol of the feedwater heating in which singlechannels have been replaced by multiple ones.


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New technology & software -

Three generations of I&C systems of NPP havebeen

installed.

1) first used analog technology for instrumentation

and relay based equipment for control.2) Second & third generation used discrete or

integrated solid state equipment for bothfunctions & latest uses digital equipment forboth.


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Digital technology has been used in all types

of industrialapplication for many years and has

been in operation in NPPs since about 1980.

Examples of the application of digital technology

for protection are described for

CANDU reactors and in French 1300 MW.


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MAIN CONTROL ROOM-Accident and post-accident management should beconducted from the main control room (MCR) by a specialteam and safety engineers. The teams ability to mitigate

theconsequences of an accident will strongly depend on thecontrol room facilities and adequacy of the monitoringsystem. Plant control room should provide indications of:

Core integrity;Reactor coolant system integrity;Containment integrity;Radiological state of the plant.


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IEC standards, guides and report

As early as the 1960s, the IEC became active in the

formulation of rules on I&C system design for NPPs.

General principles and characteristics as well as

recommended test methods were early topics promoted by

Technical Committee.

There are two subcommittees SC45A (ReactorInstrumentation) and SC45B (Radiation ProtectionInstrumentation).


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DIGITAL ELECTRONICS- Digital electronics technology has rapidly taken over the

bulk of new electronic applications for NPP increasedfunctionality, lower cost, improved reliability and reducedmaintenance requirements.

Relay logic has been replaced almost completely bydigital logic. Control panel instruments (controllers,display meters, recorders, etc.) have essentially becomedigital devices.

The majority of diagnostic equipment and measuringinstruments have become digital and provide moreaccurate and reliable readings than their analog counterparts.


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MICROPROCESSOR BASED SYSTEMS-

Microprocessors have I&C systems with their capability forconvenient programming of complex tasks, they have

foundapplications in NPP.

. Many applications which would, in the past, have usedrelays to implement logic are now largely built using

microprocessorbased programmable logic controllers(PLCs).

PLCs provide a huge range of capabilities and functionsthat

were not possible with relays.


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Present situation

The need to enhance safety and performance factors, aswell as to reduce engineering and construction costs,

has greatly increased the awareness of qualityassurance (QA) for all NPP systems.

In particular, software QA has received considerable

attention in the last decade because of the increasinguse of software based I&C systems and continuingdifficulty in establishing quantifiable measures forsoftware reliability


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Future situation

In future, a great deal of experience in plant and systemdesign, operation and maintenance will be available and

margins to preserve safety will need only be very small.Indeed there will be economic pressure to make them assmall as possible.

Fully automatic control systems and a protective structurebased on a defence in depth strategy and/or with diversefunctions will be fitted. These will be implemented withextended, distributed, digital techniques.


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Nuclear Fuel Cycle

We will start the nuclear fuel cyclewith a brief explanation of hownuclear energy works, theenrichment process, and thenpower reactors. Following will be

information on Three Mile Islandand Chernobyl, the risk of reactorleaks, and the impacts on thecommunities and the environment.Then we will discuss the nuclearweapons program, including the use

of depleted uranium, Hiroshima andNagasaki, weapons testing, and theeffects on soldiers, victims,communities, and the environment.

Source: http://www.sonic.net/~kerry/uranium.html
http://www.sonic.net/~kerry/uranium.htmlhttp://www.sonic.net/~kerry/uranium.html


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Key terms

Nuclear energysynonymous with atomic energy, is the energy produced by fission orfusion of atomic nuclei.Atomsare made of three main parts: protons, neutrons, and electrons . The protons and

neutrons make up the center of the atom while the electrons orbit around the center .Atomic numberthe number of protons in an element that identifies it.Isotopeif an atom has a different number of neutrons from protons. Isotopes, measured

by their total weight called mass number are the sum of neutrons and protons. Someisotopes are unstable and will decay to reach a stable statethese elements areconsidered radioactive.

Ionif an atom has a different number of electron from protons.Fission occurs when an atoms nucleus splits apart to form two or more different atoms.

The most easily fissionable elements are the isotopes are uranium 235 and plutonium239. Fissionable elements are flooded with neutrons causing the elements to split.When these radioactive isotopes split, they form new radioactive chemicals and releaseextra neutrons that create a chain reaction if other fissionable material is present. While

Uranium, atomic number 92, is the heaviest naturally occurring element, many otherelements can be made by adding protons and neutrons with particle accelerators ornuclear reactors. In general, the fission process uses higher numbered elements.

Fusionis the combining of one or more atomsusually isotopes of hydrogen, which aredeuterium and tritium. Atoms naturally repel each other so fusion is easiest with theselightest atoms. To force the atoms together it takes extreme pressure and temperature,this can be produced by a fission reaction.

Source: The Green Peace Book of the Nuclear Age by John May and Energy and the Environment byJames A. Fay and Dan S. Golomb.


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Transportation

Radioactive materials aretransported from themilling location to theconversion location, thenfrom the conversion

location to the enrichment location, then from the enrichmentlocation to the to the fuel fabrication facility, and finally to thepower plant. These materials are transported in specialcontainers by specialized transport companies. Peopleinvolved in the transport process are trained to respond to

emergencies. In the US, Asia, and Western Europetransport is mainly by truck, and in Russia mainly by train.Intercontinental transport is usually by ship, and sometimesby air. Since 1971 there has been over 20,000 shipmentswith no incidents and limited operator exposure.

Source: http://www.world-nuclear.org/info/inf20print.htm

Picture: http://www.ocrwm.doe.gov/wat/facts.shtml
http://www.world-nuclear.org/info/inf20print.htmhttp://www.ocrwm.doe.gov/wat/facts.shtmlhttp://www.ocrwm.doe.gov/wat/facts.shtmlhttp://www.world-nuclear.org/info/inf20print.htmhttp://www.world-nuclear.org/info/inf20print.htmhttp://www.world-nuclear.org/info/inf20print.htm


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Russian RBMK

Reaktor Bolshoy Moshchnosti Kanalniy


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Reactor Hazards

Reactor pose a serious threat radiation threatespecially tothe employees and surrounding communities. Recently theNew York times featured an article Extraordinary ReactorLeak Gets the Industries Attention. The implication is that ifthis reactor can leak, so can others. Typically, the reactors

develop boric acid under their lidswhich eats away at thesteel encasement (fixable), but this leak is in at the bottom ofa reactor.* In an article featured on CorpWatch, BechtelsNuclear Nightmares talks about a reactor that the Bechtelcorporation built in San Onofrethats been shut down since1992 for lack of safety upgrades. The problem is that there

is no place to permanently send the reactor to and is a riskbecause it was built on a fault line.** Three Mile Island andChernobyl are two of the worst incidences of reactorbreaches and are explained in the following slides.

*Source: www.nytimes.com/2003/05/01/national/01NUKE.html

**Source: www.corpwatch.org/issues/PRT.jsp
http://www.nytimes.com/2003/05/01/national/01NUKE.htmlhttp://www.corpwatch.org/issues/PRT.jsphttp://www.corpwatch.org/issues/PRT.jsphttp://www.nytimes.com/2003/05/01/national/01NUKE.html


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Weapons Transportation

Another significant threat is planes armed withthese weapons can (and have) crashed; andsubmarines have also sunk into the ocean. Inaddition there have been incidents in which

material has just been dumped as well. Mayestimates that there are 60 nuclear weaponsand 10 reactors on the ocean floor fromsubmarines, plane crashes, and dumping.

Although very strong casings likely guard them,the casings will eventually corrode resulting inradioactive contamination of our ocean andmarine life.

Source: The Green Peace Book of the Nuclear Age by John May


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Sources

DU article http://news.bbc.co.uk/2/hi/in_depth/2860759.stm

The Green Peace Book of the Nuclear Age by John May

Atomic Veterans website http://www.aracnet.com/~pdxavets/

Arms Control website http://armscontrol.org/

WWW A bomb museum http://www.csi.ad.jp/ABOMB/

UK Chernobyl site http://www.chernobyl.co.uk/

TMI picture: http://www.libraries.psu.edu/crsweb/tmi/tmi.htm

Navajo Indian Miners http://www.inmotionmagazine.com/brugge.html

WISE http://www.antenna.nl/wise/uranium/uisl.html
http://news.bbc.co.uk/2/hi/in_depth/2860759.stmhttp://www.aracnet.com/~pdxavets/http://armscontrol.org/http://www.csi.ad.jp/ABOMB/http://www.chernobyl.co.uk/http://www.libraries.psu.edu/crsweb/tmi/tmi.htmhttp://www.inmotionmagazine.com/brugge.htmlhttp://www.antenna.nl/wise/uranium/uisl.htmlhttp://www.antenna.nl/wise/uranium/uisl.htmlhttp://www.inmotionmagazine.com/brugge.htmlhttp://www.libraries.psu.edu/crsweb/tmi/tmi.htmhttp://www.chernobyl.co.uk/http://www.csi.ad.jp/ABOMB/http://armscontrol.org/http://www.aracnet.com/~pdxavets/http://news.bbc.co.uk/2/hi/in_depth/2860759.stm

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