ML20215M881

Rev 2 to Training Lesson Plan GE-LP-005-C, Radiation Protection - Exposure Reduction Techniques

ML20215M881
Person / Time
Site:	Vogtle
Issue date:	09/08/1986
From:	Green L GEORGIA POWER CO.
To:
Shared Package
ML20215M870	List: ML20215M869 ML20215M874 ML20215M877 ML20215M881 ML20215M887 ML20215M890 ML20215M892
References
GE-LP-005-C, GE-LP-5-C, NUDOCS 8611030405
Download: ML20215M881 (12)

Text

.

, , Georgia Power

,, POWEl GENERAiaON DEPARTMENT VOGTLE ELECTRIC GENERATING PLANT TRAINING LESSON PLAN RADIATION PROTECTION - EXPOSURE I

REDUCTION TECHNIQUES NUMBER: ct_tp_005-c PROGRAM: GENERAL EMPLOYEE TRAINING REVIS10N: 2 AUTHOR:

LEATRICE G. GREEN DATE:

9/4/86 APPROVED:

if.A.V Q m DATE:- 9l% l&

U INSTRUCTOR GUIDELINES:

I. LESSON PRESENTATION - 30 MINUTE LECTURE. INCLUDING REVIEW, 5 MINUTE FORMATIVE TEST.

II. MATERIALS REQUIRED: SLIDES, TRANSPARENCIES, SLIDE PROJECTOR, OVERHEAD PROJECTOR, AND HANDOUTS.

OPTIONAL: SHIELDING MATERIALS A. PAPER B. PLASTIC C. PLYWOOD D. LEAD E. PARAFFIN

)

.s 3

4 t,,h.g$[:,

?" 's 86110 403 es1%gDR OCK 0300 PDR E

i

O

. - GE-LP-005-C PURPOSE STATEMENT:

1.

TO INTRODUCE THE TRAINEE TO THE ALARA CONCEPT AND PROVIDE HIM WITH KNOWLEDGE AND SKILLS WHICH WILL HELP HIM MINIMIZE HIS EXPOSURE TO RADIATION.

II. LIST OF OBJECTIVES:

This module is designed to enable the trainee to:

1. Identify the sources of alpha, beta, gamma and neutron radiation found in s nuclear power plant. (Review)

2. Identify the effect of plant operating status on radiation levels.

3. Identify the ALARA concept and apply the principles of time, distance, and shielding to minimize radiation exposure.

4. Identify the correct action to take if an RWP indicates that an ALARA review is required.

5. Given a dose rate for a work area and a time estimate for accomplishing a task, compute the dose which would be received by a worker performing the task.

6. Apply the knowledge of effective shielding materials acquired earlier in this class to select appropriate methods and materials for shielding against exposure to alpha, beta, gamma and neutron radiation.

7. Apply the practices embodied in the ALARA concept, along with sound judgement, to select the proper course of action from among several alternatives in a given situation.

2

. . GE-LP-005-C

REFERENCES:

1. 10 CFR 19 AND 10 CFR 20

2. USNRC REG. GUIDES 8.13, 8.27, 8.29

3. VEGP - 40000 SERIES PROCEDURES

/- . " HEALTH PHYSICS FUNDAMENTALS" - GENERAL PHYSICS CORPORATION

5. " RADIATION PROTECTION" - GENERAL PHYSICS CORPORATION

6. " FUNDAMENTALS OF PHYSICAL SCIENCE" - GP CORPORATION

7. " INTRODUCTORY HEALTH PHYSICS COURSE" - HOUSTON LIGHTING AND POWER CO.*

8. " RADIATION RISKS FOR NUCLEAR WORKERS" - ATOMIC INDUSTRIAL FORUM

9. " BASIC RADIATION PROTECTION SLIDE SERIES" - NUCLEAR SUPPORT SERVICES, INC.

10. " RADIATION SAFETY TECH. TRAINING COURSE" - H. J. M0E

11. SER 85.50, SECTION B

12. SOER 85.003 e

4 3

GE-LP-005-C ll1. LESSON OUTLINE: NOTES I. INTRODUCTION Although radiation exposure limits have been established as described in the previous module, it is prudent to assume that any exposure to radiation is potentially harmful. Thus, every effort should be made to, minimize radiation exposure.

A. Sources of Radiation (Review)

1. Alpha -< uranium fuel (normally contained in cladding)

2. Beta and Gamma

a. Radioactive waste

b. Contaminated tools and equipment

c. Most fluid transfer systems in plant

3. Neutron - Operating reactor Alpha and neutron radiation are relatively minor sources of radiation in most power plants because exposure to them is improbable for most workers. Beta and gamma are the two major exposure sources and, of the two, gamma is probably responsible for mor.e dose received because of its high penetrating power.

B. Effect of Plant Operating Status on Radiation Levels It is important to be aware that radiation levels in a given location in the plant may change from day to day, depending on plant operating status.

1. Radiation levels can change significantly within SOER 85.003 a short period of time in some locations in the plant depending upon the operating status. Some of these areas include:

a. Reactor cavity area especially with the incore instrument thimbles withdrawn.

b. Area near Fuel Transfer Tube, especially during spent fuel assembly transfer.

c. Waste Process System, especially radwaste collection tanks, gas holdup / decay tanks and bottom sludge tanks.

d. Reactor Refueling Cavity

e. Seal table area when thimbles are withdrawn

f. Reactor Water Cleanup System

• Do not assume radiation levels are constant! Follow instructions on RWP.

4 t

. - GE-LP-005-C lil. LESSON OUTLINE: NOTES

2. Underwater work in radiation areas present several conditions:

a. Shielding provided by H O can reduce dose rates 2

but may cause disadvantages such as:

1) Diff'iculty in accurately assessing the work area dose rate

2) The possibility of rapidly changing radiation fields due to the mobility of crud or fuel debris in the water

b. Worker is mobile, shielding effect is not constant. The unique nature of underwater work requires special radiological protection procedures in addition to special equipment.

3. Performing work in potentially high rad areas warrant SER 85.50 extreme caution by all personnel involved in the work. 12/12/85 The following actions should be taken:

a. Radiation levels should be verified before work begins.

b. Never assume an expected level of radiation in any location.

c. Perform all work according to the RWP.

d. Respond promptly if radiation monitors / alarms are activated.

Always take the most conservative response to any radiation monitor indication or alarm.

C. ALARA ALARA Philosophy or concept is that all reasonable steps be taken to keep doses as low as possible while still getting the work task accomplished. Concept consists of many specific requirements for conducting work in a Radiological Area. ALARA requirements and work, techniques can often be utilized by every worker for each task they perform.

Job planning and pre-job preparation are essential characteristics of a successful ALARA program.

5

GE-LP-005-C l Ill. LESSON OUTLINE: NOTES In addition to providing an upper limit on a persons permissible radiation exposure, the NRC requires that its licensees maintain occupational exposures as far below the limit as is reasonably achievable (ALARA)

This means that every activity at a nuclear facility involving exposure to radiation should be planned to minimize unneces'sary exposure to individual workers and also to the worker population.

A job that involves radiation exposure should be scheduled only when it is clear that the benefit justifies the assumed risks. All design, construction and operating prccedures should be reviewed with the objective of reducing unnecessary exposures.

All radiation workers are responsible for keeping their radiation exposure As Low As Reasonably Achievable (ALARA).

Three factors which can be controlled to minimize exposure are time, distance, and shielding.

1. Time - the radiation dose received is equal to the dose rate at a given location multiplied by the time spent in that location.. Thus, by reducing the amount of time spent in a radiation area, the radiation dose to the body can be reduced.

Do not Loiter. When USE EXAMPLES OF DOSE CALCULATIONS AND EXPLAIN work is co nplete or THAT DOSE RATE MEANS DOSE PER UNIT TIME. terminated, leave the area immediately,

a. Methods of reducing exposure time are:

1) Plan the job to be performed (pre-job planning.

2) Carefully select all tools needed for the job.

3) Practice on mock-up prior to performing job.

4) Use experienced personnel to train new workers.

Less time spent in a radiation area, the less your dose.

~

2. Distance - radiation rapidly loses its intensity as it travels across a distance. Thus, by increasing a worker's distance from a radioactive source, the radiation dose to his body will be reduced.

Primary effect is an inverse square reduction in intensity not energy of a point source. Gamma rays from Co-60 have a mean free path in air of several hundred meters.

6

GE-LP-005-C lli.

~

LESSON OUTLINE: NOTES Point source --- Inverse square reduction Exposure can also be reduced using the following:

a. Remote operations

b. Long-handled (extension) tools Always move to areas where work area dose rate is lower when work is delayed or inspected.

3. Shielding - radiation expends its energy by Types of Shielding interaction with matter. Therefore, if appropriate shielding material is placed between a worker and the 1. Permanent-installed source the radiation dose to his body will be reduced. during construction Appropriate shielding materials are summarized below. of the plant.

RADIATION TYPE SHIELDING MATERIAL

a. Alpha paper, clothing

b. Beta tin, aluminum, plastic, wood

c. Gamma ,

lead, steel, concrete

d. Neutron water, wax (paraffin)

NOTE: All shielding must be installed with Health 2. Temporary installed Physics guidance. Workers should never install as the need arises.

or remove shielding without H.P. supervision.

However, they should always be alert for the possibility of using " installed components" as shielding. Temporary Shielding Materials:

4. Examples of the Use of the ALARA concept: a. Lead bricks

b. Lead blankets

a. Has the ALARA concept been applied if, instead c. Lead sheets of reaching dose limits during the first week d. Water (fuel pools) of a quarter, the workers dose is spread out e. Plywood over the whole quarter? f. Polysheets No. For radiation protection purposes, risk of cancer from low doses is assumed to be proportional to the amount of exposure, not the rate that it is received. Thus, spreading dose out over time or over larger numbers of people does not reduce the overall risk. The ALARA concept has been followed only when the individual and collective doses are reduced by decreasing time of exposure and radiation levels in the individual and collective doses are reduced by reducing exposure time or decreasing radiation levels in the working environment.

7

. . GE-LP-005-C

~

111. LESSON OUTLINE: NOTES

b. Collective dose (person-rems). The sum of all In considering risk to occupational radiation exposure received by all a total population it workers in an entire worker population. is the collective dose that must be

1) Example: If 100 workers each receive 2 controlled. For a rems the individual dose is 2 rems and given collective dose, the' collective dose is 200 person-rems. the number of health effects is assumed to The total additional risk of cancer and be the same even if a genetic effects in an exposed population larger number.of is assumed to depend on. collective dose. people share the dose.

Spreading the dose out Efforts should be made to maintain the may reduce the collective dose ALARA so as to not individual risk, but unnecessarily increase the overall not that of the population incidence of cancer and genetic population.

effects.

2) Example: Is the use of extra workers a good way to reduce risk?

Yes and no. For a given job involving radiation exposure the more people who share the work, the lower the average dose to an individual. For lower dose, lower risk to an individual the answer is yes.

Considering the risk of the entire group of workers using NRC purposes of pro-tection, the risk of cancer depends on the total amount of radiation energy absorbed by human tissue, not on the number of people to whom the tissue belongs.

Case: If 30 workers are used to do a job instead of 10, and if both groups get the same collective dose, the total cancer risk is the same and nothing was gained for the group by using 30 workers. From this standpoint the answer is "NO". The risk was not reduced but simply spread among a larger number of persons.

c. Spreading the risk around often results in larger collective doses for a job. Workers are exposed as they approach a job, while they are getting oriented to do the job and as they withdraw from the job; the dose from these actions is called non-productive.

8

. . GE-LP-005-C ll1. LESSON OUTLINE: NOTES If several crew changes are required, the non-productive dose can become very large. So, the use of extra workers may actually increase the total occupational dose and the resulting collective risks. Reduce risk by reducing collective dose, which is reduced Table 5 lists the average occupational by decreasing exposures for workers who had measurable radiation levels, exposure above background levels in various working times or both, occupations based on the 1975 date.

5. ALARA Review Program - To assist workers in applying the ALARA principles, an ALARA review program has been established at Plant Vogtle. If any of the following conditions exist in connection with a job described on an RWP, those who will perform the work must attend a special ALARA briefing before the RWP is approved.

ALARA REVIEW PROGRAM TO BE VERIFIED UPON COMPLETION OF PROCEDURE. .

a. Conditions Requiring ALARA Review

1) Man-rem estimate on RWP is greater than 1 man-rem.

2) Any individual on work crew is subject to receiving more than 200 mrem.

3) Smearable contamination is such that respirators must be worn (greater than 50,000 dpm/100 cm2 ),

4) A system is to be breached.

5) Other special radiological conditions exist (as determined by the ALARA review committee).

TRAINEES ARE NOT REQUIRED TO BE FAMILIAR WITH THESE CONDITIONS.

Each RWP will indicate whether an ALARA review briefing is required. If a briefing is required, those who will be using the RWP are responsible for reporting to the ALARA oifice to arrange for the briefi ng, before doing the job.

9

, . GE-LP-005-C Ill. LESSON OUTLINE: NOTES II.

SUMMARY

Review objectives using examples to illustrate how each might be tested.

ADMINISTER FORMATIVE TEST FOLLOWING OBJECTIVES REVIEW, ALLOWING A MAXIMUM OF 5 MINUTES FOR COMPLETION. REVIEW TEST, GIVING PARTICULAR ATTENTION TO ANY PROBLEM AREAS IDENTIFIED.

ALLOW TRAINEES TO KEEP TEST PAPERS AS STUDY AIDS BUT TRY TO BE AWARE OF WHO IS HAVING DIFFICULTY.

10

GE-LP-005-C TABLE 5 U.S. OCCUPATIONAL EXPOSURE ESTIMATES" OCCUPATIONAL AVERACE WHOLE- COLLECTIVE SUBGROUP BODY DOSE (Person-rems)

(millirems)

Medicine 320 51,400 Industrial Radiography 580 5,700 Source Manufacturing 630 2,500 Power Reactors 760 21,400 Fuel Fabrication and Reprocessing 560 3,100 Uranium Enrichment 70 400 Nuclear Waste Disposal 920 100 Uranium Mills 380 760 Department of Energy Facilities 180 10,100 Educational Institutions 206 1,500 Transportation 200 2,300

" Adapted from Cook and Nelson, Occupational Exposures to Ionizing Radiation in the United States: A Comprehensive Summary for 1975, Draft, Environment Protection Agency.

i 11 l

m 3 GE-LP-005-C r.

TEST 5 - EXPOSURE CONTROL (PART II) NAME Time Allowed: 5 minutes SSN Write a word "True" or " False" in the blank preceding each of the following statements.

1. The primary source of neutron radiation during plant operation is the reactor. ,

2. The only source of neutron radiation when the plant JLjt not operating is the reactor vessel shield wall.

3. Plant operating status generally has little effect on radiation levels in the plant.

4. A welder would receive a dose of 300 mrem while working for 15 minutes in an area having a dose rate of 20 mrem /hr.

5. The dose rate from a radioactive source decreases as the distance from the source increases.

6. Two inches of lead will stop all alpha, beta, and gamma radiation.

7. Stainless steel is probably the most practical material for shielding against beta radiation.

8. Wearing protective clothing will reduce the dose received while working in a high radiation area.

9. You are working near a pipe valve which you believe to be emitting high levels of radiation. If you must continue working in the area, you should wrap the valve in a sheet of lead if you can find one nearby.

10. If an alara review is required by an RWP, workers should report to the alara office as soon as the job is complete.

11. Concrete is often used to shield alpha radiation.

12. Compute the dose received by a worker who remains for 30 minutes in an area where the dose rate is 200 mrem /hr.

12