9-1

UNIT NINE

ENVIRONMENTAL MONITORING

GATE FRAMEQUESTION

Information concerning the characteristics of potential andactual releases of radionuclides are needed to determineemergency action levels (e.g., PAGs), to recommendprotective action, and to identify critical exposure pathways.This information can be obtained by environmentalmonitoring.

This unit will cover the main objectives and purposes forenvironmental monitoring, as well as the instruments used. This topic is covered in detail in FEMA’s RadiologicalAccident Assessment courses. In this course the unit isintended as a review for those participants who have alreadymastered the competencies involved, and a critical learningobjective for those who have not.

Define “environmental monitoring” and state at least twopurposes for environmental monitoring.

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ANSWERS

Your answer should includethe adjacent information

Environmental monitoring is the assessment of the actual orpotential exposure of an individual to radioactive materialswhich may be present in his or her environment.

Environmental monitoring is the assessment tool which mayalso confirm the absence of radioactive materials in theenvironment.

Purposes for environmental monitoring include:

• Verifying that the release has occurred;

• Providing data for input into analytical models;

• Defining affected areas; and

• Estimating hazards to the public.

If your answer included all or most of the above points, youshould be ready for the summary questions at the end ofthis unit. Turn to page 9-14.

If your answer did not include these points, it would beadvisable for you to complete the programmed instructionfor this unit. Turn to page the next page.

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QUESTION

Circle the correct answer

ENVIRONMENTAL MONITORING

Environmental monitoring is the assessment of the actual orpotential exposure of an individual to radioactive materialspresent in his or her environment. Depending on the natureof the radioactive release, both short-term and long-termenvironmental monitoring may be necessary.

Short-term measurements, which are performed byemergency personnel during the period of the initialemergency response, are primarily aimed at providinginformation for analysis and data for determiningappropriate action levels and mitigation measures.

Long-term monitoring is generally conducted by supportingor consulting personnel after the release is terminated, and isperformed to provide detailed analyses of radiologicalhazards and accident consequences.

Monitoring results can be used to verify that a release hasoccurred, provide data for input into analytical models, anddefine affected areas. Measured data can also be used toestimate hazards to the public.

Conversely, monitoring results may confirm the absence of aradiological hazard.

To test your knowledge of environmental monitoring,answer the following question.What type of environmental measurements are made todetermine appropriate action levels and mitigatingmeasures?

a. short-term.

b. long-term.

Turn the page to check your answer.

Unit Nine Environmental Monitoring

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ANSWERS

QUESTION

Circle the correct answer

a. Correct answer. Protective actions should beimplemented, if warranted, as soon as possible. Short-term measurements would yield results thatcould provide a basis for decisions leading to aprompt and appropriate emergency response.

Proceed to page 9-6.

b. Incorrect. Long-term measurements are performedto provide detailed analyses of radiological hazardsand accident consequences.

Try another problem.

Environmental monitoring results can be used to estimatehazards to the public.

a. true.

b. false.

Turn the page to check your answer.

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ANSWERS a. You’re right.

Move on to the next section.

b. Wrong answer. The statement is true. Radiationdata generated by environmental monitoring canhelp determine whether exposure levels are highenough to create a hazard to the public.

Review this section before moving on to the next section.

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9-6

Desposition on Ground from Irrigation

Direct exposure from air

Direct exposure from ground

Deposition on ground due to plume depletion

Contaminated water supply

ENVIRONMENTALMONITORING PROGRAMS

EPA’s Manual of Protective Action Guides and ProtectiveActions for Nuclear Incidents (EPA 400-R-92-001)identifies three categories of exposure pathways and thedose levels at which protective actions are indicated. Exposure may result from whole body external exposure,inhalation of suspended particulate radioactive materials, orfrom ingestion of contaminated food and water. Anenvironmental monitoring program must be in place so thatin a nuclear incident, potential dose levels in any or all ofthese potential exposure pathways may be projected.

The function of an environmental monitoring program is toacquire sufficient radiation data to confirm protective actiondecisions that have been made in time to ensure thatradiation exposure to the public will be as low as isreasonably achievable (ALARA). By the same token, it isnecessary to consider keeping the cost of the programwithin reasonable limits, without compromising ALARAexposure, by utilizing existing instrumentation and resourceswhenever possible. Therefore, planning for the design andimplementation of the program must be thorough to assurea rapid and proper response in the event of a radiologicalaccident.

Effective evaluation of gathered information and coordination ofenvironmental monitoring activities require the establishment of asound environmental monitoring program. This program shouldbe run by a facility staffed by personnel capable of directing fieldoperations and interpreting analytical and measured results. Thisfacility must have reliable communications capability to primaryand backup monitoring personnel, emergency directors,laboratory facilities, transportation agencies, and weatherservices.

Unit Nine Environmental Monitoring

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QUESTION

Circle the correct answer

Environmental monitoring facilities must be licensed. The licensewill spell out the extent of the required environmentalmeasurements. Many licenses require that monitoring play alimited role because the radionuclide involved poses little risk tothe public. In contrast, facilities such as waste burial grounds,nuclear power stations, and fuel processing plants requireextensive monitoring programs.

To check your understanding of these concepts, answer thefollowing question

One reason for maintaining an environmental monitoringprogram is

a. to acquire sufficient radiation measurement resultsto confirm protective action decisions.

b. to promote the benefits of radionuclides in moderntechnology.

Turn the page to check your answer.

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ANSWERS

QUESTION

Circle the correct answer

a. Right! The protective action decisions ensure thatradiation exposure to the public are at ALARAlevels. Such decisions could not be made withoutknowing the radiation levels at hand.

Continue to the next section.

b. No. Although radionuclides do play an importantrole in many facets of today’s technology (such asradiotherapeutics and research), their benefits arenot promoted by environmental monitoringprograms. These programs are designed to provideenvironmental radiation data that aid in the planning,response, and analysis stages of a radiologicalincident.

Try another question.

All facilities utilizing radiation should maintain extensiveenvironmental monitoring programs.

a. true.

b. false.

Turn the page to check your answer.

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ANSWERS a. Incorrect. Some facilities use radionuclides inamounts that pose very little risk to the public. These places do not require extensive monitoring. Other facilities may use radionuclides in amountsthat are hazardous to the public, and thereforerequire much more extensive environmentalmonitoring programs.

You should reread this section before proceeding.

b. Correct answer. You understand that not allfacilities have the same requirements for theirenvironmental monitoring program.

Go ahead with the next section.

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AIRBORNE RELEASE

MILK

ENVIRONMENTALMONITORING INSTRUMENTATION

For airborne releases, measurements to be made by initialenvironmental monitoring teams include dose rate in air,airborne particulate activity, and airborne iodine activity.

Dose rate can be measured using a standard radiationsurvey detector (movable window ionization detector) heldat waist height. This measurement provides an indication ofthe radiological hazard resulting from whole-body exposureto external gamma rays from immersion in the plume andfrom ground contamination.

Airborne particulate activity can be measured using high-volume, high-efficiency filtered or impact air samplers. Particulate samples can be evaluated in the field for alphaand beta-gamma activity using standard survey meters.

Fixed instruments used for airborne environmentalmonitoring include passive dosimeters (thermoluminescentor film), airborne particulate filters, and iodine absorbercanisters.

Iodine-131 is the nuclide of major concern in contaminatedmilk because it is deposited in the human thyroid and thethyroid is a critical organ. The instrument system currentlyrecommended for field monitoring of milk at the preventivePAG level is a hand-held Sodium Iodide (NaI) detector. This instrument system should be used with the ionexchange method, a filtering and collecting process. However, this system is also sensitive enough to be usedwith the immersion method for milk sample monitoring. Available information indicates that other types of hand-heldinstrumentation such as Geiger-Mueller or ion chamberdetectors are not sensitive enough for this task.

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NON-DAIRY FOODAND WATER

QUESTION

Circle the correct answer

After emergency monitoring of surface-depositedradioactivity defines the boundaries of contaminated areas,non-dairy food and drinking water within the boundariesshould be sampled and analyzed. Laboratory tests on foodsamples may include strontium analyses or other chemicalseparations. Field monitoring instrumentation for watershould be similar to that recommended for emergency milkmonitoring, i.e. immersion counting or ion-exchange resincounting.

Try the following question to apply your knowledge ofenvironmental monitoring instrumentation.

Airborne particulate samples can be collected using

a. column anion resin exchange.

b. high-volume, high-efficiency filtered air samplers.

Turn the page to check your answer.

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ANSWERS

QUESTION

a. Wrong answer. Airborne particulate matter iscollected using high volume air samplers or fixedparticulate filters. The column anion resin exchangemethod is used for liquids.

Try another problem.

b. Yes, you are right.

Go ahead to the next section.

Ionization detector measurements provide an indication ofthe radiological hazard resulting from whole-body exposureto external fromimmersion in the plume and from ground contamination.

a. alpha radiation.

b. gamma radiation.

Turn the page to check your answer.

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ANSWERS a. No. Ionization detectors can only detect gammaradiation.

You should go back and reread that section beforeproceeding to the Summary Questions.

b. Correct answer.

Proceed to the Summary Questions.

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QUESTION

SUMMARY QUESTIONS

1. Facilities such as radioactive waste burial grounds,nuclear power stations, and nuclear fuel processingplants

a. do not require extensive environmentalmonitoring programs.

b. require extensive environmental monitoringprograms.

Turn the page to check your answer.

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ANSWERS

QUESTION

a. Incorrect. The sources at these facilities mayproduce high level radiation doses. Their licensesrequire extensive monitoring programs.

Go back to page 9-3 and review before answering the nextSummary Question.

b. Correct.

Move on to the next Summary Question.

2. Initial environmental monitoring involves radiationmeasurements in

a. air.

b. food.

Turn the page to check your answer.

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ANSWERS a. Correct.

Proceed to Unit Ten.

b. Incorrect. It is unlikely that initial environmentalmeasurements will detect radioactivity in food. Although food contamination does occur, it cannotbe measured immediately after the radiologicalincident.

Go back to page 9-3 and review before proceeding to thenext unit.