ML19350A498

Forwards Trip Rept of 810121-22 Technical Workshop in Denver,Co Re Specific Protocols Being Used by NRC & SD for Edgemont Cleanup Action Program.Protocol Encl

ML19350A498
Person / Time
Issue date:	02/18/1981
From:	Scarano R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Zeimet M EDGEMONT, SD
References
REF-WM-40 NUDOCS 8103160329
Download: ML19350A498 (39)

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FEB i s 193; hiiUR WM-40 Mr. Mayor P. Zeimet City of Edgemont Edgemont, South Dakota 57735

Dear Mayor:

On January 21 and 22,1981, a technical workshop was held in Denver, Colorado to discu-the specific protocols being used by the NRC and the State of South Dako:

for the Edgemont Cleanup Action Program.

I've attached for your information uy trip report for the workshop and a copy of the subject protocol.

As noted in the trip report Battelle will issue a detailed proceedings. We will send you a copy as soon as it is available.

If you have any questions regarding the material please feel free to contact ne at 301-427-4103.

. pffj, Ross A. Scarano, Chief Uranium Recovery Licensing Bear.ch Division of Waste Mariagement cc: John "rueger R. Richardson t-

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MEMORANDUM FOR:

John B. Martin, Director Division of Waste Management, ?NSS..

FROM:

Ross A. Scarano, Chief Uranita Recovery Licensing Branch Division of Waste Management.

SUBJECT:

TRIP REPORT

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On January 21, and 22,1981, we conducted a peer review of the technical aspects of our Edgemont Clean-Up Action Program in Denver, Colorado.

The meeting attendees consisted of organizations.and scientists that have been involved in radon monitoring associated with misuse of

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uranium tailings at other locations in the U. S. and the interested parties associated with Edgecont. The Attendee list is attached.

Our contractor Sattelle Pacific Northwest Laboratories (PNL) made an excellent presentation of the program and results to date.

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PNL is preparing detailed proceedings of the meeting but the folicwing is a general su parization of the conclusions.

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1)

The program being implemented by PNL is a sound technical program.

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Minor variations in sampling and analytical techniques shoud (and will) be incorporated into the program. These variations a

may lead to more expeditious and less costly methods of verifying the effectiveness of remedial actions. For example, use newly developed simple passive radon monitoring devicas in parallel with the more ctmibersome traditional air sampling equipment.

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The EPA representative concluded that in his opinion the program meets the intent of the EPA criteria established for the DOE re:edial action plan (UMTRCA).

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noss A. Scarano, Chief Uranitmi Rec:very Licensing 3 ranch Division of Waste Management cc: See attached sheet.

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ATTENDEES

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Nuclear Regulatory Comission ~

Gregory G. Eadie '

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Don F. Harmon

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. f-Bill Thomas Satte11e Pacific Northwest Lt boratorie's'.~,

Pete Jackson Jia Young Richard W. Perkins

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Ned Wogman

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John Bernhardt Environmental Protection Agency.

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Jack Thrall

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2 Don Groelsema Department of Energy-f Ray Cooperstein David Ball John G. Themelis Bud Franz Colorado Department of HW.th Hal Langer Ken L. K. Weaver

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. Al Hazle Michael L. Brown Bob Ovemyer Ford, Bacon & Davis Utah Tom Donovan Tennessee Valley Authority Bob Powers Ralph Wallace John Tipton EG&G.

Fred Haywood Dak Ridge National Laboratories John Witherspoon Bob Wynveen

- Argonne Natianal Laboratories

• 4 alt Smith Michael Mcmeni Walt Kisieleski

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John J. Endres Housing Urban Development Craig McIntyre South Dakota Planning Bureau l

Randy Erich South Dak~ota Health Department

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Edmond i!, Noel Jr.

Attorney Marilyn Alkire Wayne Gisler Sendix Grand Junction Ccmpany Miegolos Abromiuh l

l Harold L. Rarrick Sandia Na':fonal Laboratories Glen Lane Council of Energy Resourca Tribes '

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Wirkshop on Radiological Surveys in support of the Edgement Clean-Up i

Action Program to Be Held January 21 and 22,1981 in Denver. Colorado On behalf of the nuclear Regulatory Commission. Office of Nuclear Material

'sfasy and Safeguards, we have been asked to organize the above workshop.

L cae oWeetives of this workshop are to present the protocol for and initial observations from the radiological survey at Edgemont. South Dakota.

Sev-eral new.and taportant observations have been made in these radiological sur-voys which wrrant early consideration and which will certainly have a beer-n.a on tan procedures which are acceptable for radiological surveys and per-i haps an the final standards which will be implemented at the other tites anece surveys are curvently being conducted.

About one wuck inr'ior to the meeting, each of you will receive from us our pectocols for the radiological surveys which are being conducted at Edgemont.

t1. t< uur hope that you will take time to review these protocols prior to the time ut attending the workshop and, if you wish. prepare formal written com-l eents or criticisans dich could be discussed at the meeting and perhaps.in-r,urpnrated in our workshop proceedings.

allo.r people' gin the workshop at 1:00 P.M. on January We plan to be 21,1981. This will from amost parts of the country to travel to Denver on the morn-ing of January 21 The workshop will include the following items.

l A briefing at our protocols and observations at Edgesont will be made during the first day.

This will include an in-depth discussion of the procadures amployed in the whole radiological survey program.

It will include a descrip-ston of espaipuumt, techniques and procedures employed in radon daughter mes-surweats within structures, radium surveys in soil near structures both on the surface and below grade. radiation measurements on open lands, actual ott-servations of redan daughter concentrations within about 300 structures in Edgemont and thir relationships to recammended standards, and the relation-

e. hip between meteoroloolcal coriditions and radon dauahter levels observed.

It is capacted that these discussions will continue on into the morning of Janusry 22.

We expect that, the majority of the second day will be levoted to a discussion of tan precocols being used at Edoomont and comments from the attendees on han these protocols campare with those they are currently using or have used to radiological surveys at other sites throughout the country.

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Wo f eel that it is very important that w recaf ve commer.t* from the attendees i

on their reeltags as to the appropriateness of the Edgemont protocols.

To the.ic.1ree possible, we hope to resolve any serious concerns regarding the tapenv.t protocols through discus:fon and, where appropriate, modificatica of these r. rut.nhwes.

A topic which we fuel may need substantial considere ion ls the long-tem monitorh=4 =(t.hin structJres to establish annual a+

age radon daughtcr levels.

It, is our Niing that past procedures for estib111;.ing such levels may be overly tardansame and possibly unnecassary.

We will, of course, present our own rwn==est.U.Ws but would appreciata your ccomments.

Pir:.no,idvt".c: the 'andersigned as soon as passible of those who will be attend-inq frems your urs.pauation and whether you would llka to make a presentation.

utcased W. Pertins Assocutt hegar Physical Selawns Department t!alid6M J29/300 Area Richland, WA 9935?

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l AGENDA FCR WORKSHCP CN RADICLOGICAL SUR7ETS El SU?? ORT OF TEZ EGZMCNT CLEAN-UP ACTICN PRCCRAM JANUART 21-22, 1981 Denver Airport Hilton Denver, Colorado JANUART 21, 1981 1:00 P.E Introductory Zamarks 3 css Scarano 1:15 P.E 3ackground information en the Greg Zadia Edgemont sita 1:30 ?.E 3atta11a's responsibility in the

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Edgemont raciological survey or Richard ?erkins PROTCCOLS TCR RADICLCG' CAL SUR7ETS 1:45 ?.1 Indoor radon daughtar measuresents

?asa Jackson 2:30 ?. 1 3raak 2:45 7.1 Indoor gannia dose rats measurements 3111 ? cmas 1:15 ?.E Outdoor gamma dose rata measurements Jim Teung 3:45 P.1 Radium measurements in soils Pete Jackson 4:15 7. 1 Discussion of protocols 9

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i JANUARY 22, 1981 8:30 A.1 Cbservat'. ens from the Edgemont Pete Jackson /

radiolosa 2_ surveys Jia Young 10:00 A.E 3reak 10:20 A.L Open discussion of Edgemont radiological

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12:00 Noon Lunch 1:00 P.E Response and discussion from workshop attendees on

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PROCEDURE FOR THE DETERMINATION OF pRCCERTY REOUIRING REMEDIAL ACTION Introduction The Nuclear Regulatory Comission has given Pacific Northwest Labora-tory the responsibility for the development of standardized procedures for the identification of offsite structures and properties that require remedial action because of elevated radiation levels caused by residual radioactivity as defined in the Uranium Mill Tailings Radiation Control Act of 1978 in the vicinity of Edgemont, Soutn Gaiota. The decision concerning remedial action is to be based upon three criteria established by the Environmental Protection Agency in 40 CFR 192, " Proposed Cleanup Standards for Inactive Uranium Processing Sites."III This proposed standard states that remedial actir. shall be required e

if residual radioactivity causes (1) average annual indoor radon decay product concentrations (incluaing background) 20.015 '4L,(2) (2) indoor gama radiation levels 120 microroentgens above background, or (3) average 225Ra concentrations in soil or other materials 15 pCi/g in any 5 cm thickness within 1 foot of the surface, or any 15 cm thickness below 1 foot.

The measurement procedures for identifying structures and property that require remedial action must, of necessity, represent a compromise between the need for accurate, representative measurements of radiological parameters and the requirement that decisions concerning remedial action be made as quickly as possible. Any delays in carrying out remedial action caused by too ex-haustive a measurement program could easily result in a greater population radiation dose than minor errors in deciding where remedial action is re-quired. Therefore, the major goal of the initial radiological measurements is to identify all sources of elevated radioactivity, for example, gamma radiation above natural background (the EPA has established an upper limit of 14.5 uR/hr for the background in the Edgemont vicinity (3)), 225Ra in soil greater than 5 pC1/g and structures which may exhibit elevated indoor working levels. However, in order to exped'ite the implementation of remedial action, the assessment of average annual working levels may have to be made at less than the' maximum possible accuracy; for example, by completing grab sampling instead of ~ conducting long-tenn measurements using the RPISU-type

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1 Feceral Register, Vol. 45, No. 79, April 22,1980 2 One working level ('4L) is defined as any ccmoination of short-lived raden decay procuc.s in 1 liter of air that will result in the ultimate emission of alpha particles with a total energy of 130 billion electron volts 3 I?A Tecnnical Note ORP/LV80-2, February, 1980

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In the following sections the procedures that at the present time are considered by Pacific Northwest Laboratory to represent the best compromise between accuracy and expediency for the identification of structures and properties that require remedial action at Edgemont, South Dakota are out-lined. These procedures were developed for the NRC and the state of South Dakota to confonn to the protocols developed and recomended by HUD, Region 8 and EPA /8(4)

A flow diagram is included that outlines the measure-ment and decision making process (Figure 1). These procedures will be dis-cussed in greater detail at the January 21-22 workshop at Denver in the hope that any possible weaknesses can be identified and eliminated.

M_e__asurement of Radon Proceny Working Levels in Homes During the initial survey of structures at Edgement, five minute air filter samples are being collected for radon progeny working level measurement using 47 m diameter millipore filters with a pore size of 0.8 microns. Air is drawn through the filters at flow rates of about 30-50 liters per minute using Gast pumps. One filter is collected in the main living area on the ground floor of each structure and one in habitable basements. One air filter is also collected at about the same time each morning outdoors at 107 N. 6th Ave. to detennine the daily variation of outdoor working 'aels.

This indicates when elevated ambient working levels may be adversely affecting indoor radon progeny grab samples. The home owners are asked to keep their i

homes closed as tightly as possible for eight hours (three hours minimum) prior to making the grab working level measurements to minimize the dilution of the radon progeny concentrations by outside air.

Comencing.less than seven minutes after the beginning of sampling, the filters are counted for three minutes using a ins scintillator to deter-218 mine the sum of the alpha emission rates of the radon progeny Po and 214Po. Two 10 minute counts are then i:aken comencing in the intervals 8-1/2 to 12 minutes and 19 to 30 minutes after the beginning of sampling to detennine the change in the emission rate with time. These measurements can be used to calculate the concentrations of the first four radon progeny in 2I8 the chain Po (3 min)g 214Pb (27 min) 21431 (20 min) 214Po (10 4sec)E 10Pb (22 yr). ~The working level is calculated from these concentrations H) Letter from J. R. Giedt, E?A to J. Endres, HUD, August 5,1980, and letter frcm J. Martin, NRC/NMSS to G. Hannen, HUD, Septeder 12, 1980

FIGUHE 1: FLOW DIAGHAM OF PROCEDUHES FOR DETEHMINATION OF PHOPEHTIES HEQUlHING HEMEDIAL ACTION 68 033 ws agetag aws.s e33 WL F

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by the general fann of the method of Thomas (Health Physics,1972).

If the ventilation rate of the structure is too great prior to the measurement, the measured working level may be below 0.01 even though the average annual working level is much greater than 0.015. The rate at which the radon progeny concentrations are depleted by dilution with outside air and plate out on the surfaces of the structure can be calculated from the 218po, 214Pb, and 81 214 degree of disequilibrium between the radon progeny using a method originally developed by Morken(5)

In practice, we use the lowest of the turnover times determined from the ratios 218 214 pof Bi and 214 214 Pb/

81 to evaluate the ventilation-plate out rate of a structure.

If Marken's model completely described the dynamic dilution processes in a structure, both ratios would yield the same turnover time. However, since actual processes rarely fit the ideal model, this test is approximate but the resulting turnover times are most useful as screening criteria to detennine when measurements should be repeated.

Based on limited data, we originally used a turnover time of 40 minutes as the minimum reasonable turnover time.

If the calculated turnover time was less than 40 minutes, the measured working level was considered to be un-I reliable (unless the measured working level was greater than 0.033) and the l

structure was scheduled for remeasurement. After a larger number of results were analyzed, we detennined that 32 minutes is a more appropriate limit since l

90% of the homes monitored had longer turnover times. If the second measure-ment also shows a turnover time less than the 32 minute criterion, it is assumed that the short turnover time is characteristic of the structure, and the measurement showing the longer residence time is used. Some structures l

wiJl regularly show short calculated turnover times either because they are leaky or because plate out of the radon progeny is. unusually rapid.

It has also been found that wind speeds greater than 8 mph cause unduly short turnover times and low -radon progeny concentrations, so we attempt not to measure working levels on days when wind speeds are above 8 mph during the few hours just prior to sampling. Should later analysis (5) Morxen, D.

A., University of Rochester, AEC Report No. UR-669-1966

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O of meteorological data indicate that working level measurements <0.033 were made under these conditions, a resampling is scheduled. Measurements greater than 0.033 WL are accepted as bemg valid.

Working Levels <0.01 If the average working level is less than 0.01 for the structure and tne ventilation rate of the structure was not too rapid prior to the measure-ment, the structure is considered to satisfy the radon progeny criterion for clearance from remedial action.

r Working levels >0.033 If the measured working level is greater than 0.033 on either floor, a second measurement is made at a later time to c:nfim the elevated concen-trations. The valid measurements taken on each floor during the initial sur-vey and during any repeat surveys are averaged ficar by floor.

(This is necessary since there may be more valid measurements available for ore floor than for another). The structure average is calculated as the average of the floor averages.

If the structure average is greater than 0.033 WL, the structure is considered to fail the working level criteria and is scheduled for engineering assessment. Mcwever, all indcor working levels above 0.01 measured on days when the cutdoor working level is above 0.015 are disre-garded and repeated at a later date because the elevated indcar working levels could be due to outside air.

Working Levels of 0.01 to 0.033 If the initial average working level measurement er the structure average measurement is between 0.01 and 0.033 WL, it is considered that grab l

samples will not provide an estimate of the average annual working level that is sufficiently accurate to providt a basis for a decision on remedial action. Therefore, the structure is sche 1J1ed for long-tem radon progeny measurements, unless the structure or ywd fails either of the other clearance criteria (gama dose rate >20 uR/hr.abow background, 22SRa >5 pCf/g in soil),

in which case it is scheduled for enginetting assessment'withcut further raden progeny measurements. The long-tem raden progeny measurements will consist l

of nominal 100 hour0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> integrated measurements taken every other month for at least six samples througnout one year in the main living area or habitable >

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basement, whichever showed the higher grab working level. Pacific Northwest Laboratory will use Radon Progeny Integrating Sampling Units (RPISU) furnished and calibrated by the EPA, Las Vegas facility, to make these measurements at Edgemont, although there are other instruments that may be used. A small pro-gram will be conducted to compare RIPSU with repeated grab samples and other sampling instruments that can be obtained to determine whether a simpler or more convenient technique other than RPISU measurements can provide suffi-ciently accurate estimates of average &nnual working levels.

Indoor Gama Surveys Indoor gama surveys are made of all habitable floors and basements

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using gama survey meters. The survey meters being used at Edgemont are Ludlum micro-R-scintillometers that employ sodium iodide crystals for gama i

detection. These instruments are ccmpared to a calibrated Reuter-Stokes pressurized ionization chamber on the ground floor of homes at least once a day. The pressurized ionization chamber is compared to a control check source daily. All instruments were calibrated at PNL prior to use and are periodically returned to PNL for recalibration. All readings taken in the field are corrected for the laboratory calibrations. Micro-R-meter readings are corrected to equivalent pressurized ionization chamber readings using the ratios detemined in that locality on the day of measurement.

Indoor gama measurements are made at an elevation.of about three feet 2

at the grid points (approximately every 5 feet) of a 25 ft grid starting at one wall. The measurements are made with the survey instrument set at slow response (long time constant). Readings are not taken until the needle has stabilized for a few seconds. Thecorrected readings are recorded on a sketch of the floor plan of the structure.

If none of the readings are above 14.5 uR/hr(0) the structure is considered to pass the gama radiation criterion for clearance.

However, if readings above 14.5 uR/hr are encountered, or if the meter shows a pronounced increase at any location, a search is made for elevated readings at surfaces of the structure.

If a reading greater than 20 uR/hr above back-ground at contact is observed, this reading is recorded. Unless the object causing the anomaly can be easily disposed of (e.g. small rocks, radium dial

~(~5 ) We nave cnosen to usa 14.5 uR/hr as the maximum background value since this upper limit of the Edgemont background was detemine by the EPA.

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clock), the structure is considered to fail the gamma criterion and is sched-uled for engineering assessment. Alternatively, the background level could be taken to be the average of the gamma readings in nearby homes that show no evidence of alcvated gamma levels unless the measured background is high-er than 14.5 uR/hr. na background varies from about 10 to 14 uR/hr with location in Edgemont. Most gamma anomalies are much greater than 20 uR/hr above background, so uncertainty as to the true background generally causes no problems.

Gamma Surveys in Garages and Nenhabitable Basements Garages and nonhabitable basements are measured at an elevation of about three feet with a Ludlum micro-R-meter set on fast response during a slow, serpentine walk through. If readings greater than 14.5 UR/hr are en-countered or the readings show a significant increase at any location, a search is made for elevated readings at surfaces. If surface levels greater than 20 uR/hr above background are measured, the property is scheduled for engineering assessment.

Outdoor Gauuna Surveys Some residential lots are very large, conc =4ni g up to two or three acres. In the case of a lot which is larger than about one acre containing a structure, the land contained within 50 feet from the structure will be surveyed using procedures for lots cour=4ning structures (see Procedure III).

Le r - inder of the land will be surveyed using the procedure for open lands (see Procedure IV).

Gamma measurements are made at an elevation of about three feet using Ludium micro-R-meters set at slow response at the grid points (appror%ately every seven feet) of a 50 ft square grid in the yards adjafling homes. ne corrected readings are recorded on a sketch of the house and yard, ne Lud-lums are cross-calibrated with pressurized ionization chunbers in' the yards of homes at least once a day. If survey readings greater than 14.5 uR/hr 1

are observed, or the r== ding sc.ows a significant increase at any location, a search is made for elevated gamma levels at the surface. If surface rv.2-ings greater than 20 uR/hr above the 14.5 uR/hr background are observed, the l

yard is considered to fail the gama criteria and is scheduled for engineer-ing assessment. Background could be taken to be the average of the gama

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1evels measured in the yards of nearby homes showing no elevated gama levels unless the measured background is greater than 14.5 uR/hr.

Surface soil samples are collected at from two to six locations shcw-ing==v4==

gamma levels. Core samples are taken when gamma readings exceed 20 uR/hr above background. These samples are analyzed using a NaI well crys-0 tal to establish the Ra content of soil at each property to confirm that 1

6 any gammaa anomaly is due to Ra, and to determine whether it is at the sur-face or below. If Ra concentrations greater than 5 pCi/g are measured in the soil samples, they are counted with germanium diodes at PNL to deter-26 230 mine (from the ratios of the Ra and Th to 3'Th concentrations) wheth-0 er the Ra is due to residual or natural radioactivity. The NaI detector cannot make this determination because of its poorer resolution, but is used in the field because its greater sensitivity permits a more rapid screening of samples. All of the scil samples collected at Edgemont are ar-chived, sealed in metal cans.

i If no readings greater than 14.5 uR/hr are encountered at an elevation of about three feet, or if no readings greater than 20 uR/hr above background are observed at ground level, only two surface soil samples are collected at 20 the locations of savi== gama readings. If Ra concentrations greater than 5 pCi/g are measured with the NaI detector, the property is scheduled for en-gi. leering assessment. If the Ra concentration is less than 5 pCi/g, the 0

yard is considered to pass the gamma and Ra criteria for clearance.

If later analyses indicated that the Ra is not residual radioactivity, the engineering ssessment will provide the home owner an indication of proce.-

dures to be used at his expense to help remedy the problem.

l Gamma Survevs of coen Land Open lots are divided into four rows perpendicular to the shorter di-mansion and five columns perpendicular to the longer dimension, unless the distance between measurements is greater than 200 ft, in which case more i

rows and/or columns are added. === readings are measured at an elevation

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of about three feet at the approximate center of each survey bicek with Lud-lum micro-R-eaters set on slow response. The micro-R-meters are compared to a calibrated Reuter-Stokes pressurized ionization chamber at one location on 1

each lot. The corrected readings are recorded on a sketch of the lot. A serpentine walk-through survey is also made between each row with the Ludium i

set on fast response. If readings greater than 14.5 uR/hr or significant increases in gasma readings are observed at any location, a search is,made I

for elevated surface readings. If readings greater than 20 uR/hr above back-ground are observed at the surface, surface soil samples and core samples are 6

l collected for Ra analysis; a.nd the lot is scheduled for engineering assess-ment.

If no ramlings greater than 20 uR/hr above background are observed at the surface, only two surface soil samples are collected at the locations of

=mv4=um gamma readings and analyzed for Ra with the NaI detector. If a 226Ra concentration greater than 5 pC1/g is measured in either soil sample, i

che sample is sent to PNL for measurement using germanium diodes, and the 0

lot is scheduled for engineering assessment. If no Ra concentration

. greater than 5 pCi/g is measured, or if the Ra is not due to residual i

radioactivity, the lot is cleared from remedial action.

If the natural 0Ra concentration is greater than 5 pCi/g, the engineering assessment will still be used to guida the homeowner, should he desire to perform remedial j

action.

Soil Sampling

• dhen indicated by the procedures described under Outdoor Canana Sur-veys and Gamma Surveys of Open Land, surface and possibly core samples of the soil are takan. The sampling procedures are at the present time being revised. Origina13f surface soil samples were taken with a spade which re-suited in a sample about 6 inches long by about 3 inches wide and about '3 inches in depth. We plan in the future a sampling device which samples a 2

200 cm area to 5 cm in depth will be used.

Originally core samples taken as part of the survey process prelim-inary to engineering assessment were taken with an 18" split tube coring de-l vice to aid early identification of surface anomaJtes as opposed to anomalies I I

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beneath the surface. The Ra concentration of the homogenized core sample was cc: mand to the Ra concentration of the surface sample to give a fia t estimate of the depth of the anomaly. The new procedure for any core samples will be to separate the top foot of the core into five separate samples (each approximately 5 cm in length) and the r-4ning six inches of core (approxi-mately 15 cm in length) will be homogenized as a sixth sample. More than one core at each location may be required to provide enough material for analysis.

These will be analyzed by gamma-ray spectrometry to determine the depth pro-file of *26Ra concentrations and those samples cont =ining greater than 5 0

pCi/g Ra will be further analyzed to determine whether the Ra is from residual or natural radioactivity.

Engineering Assessment Any property faiHng any of the following clearance criteria is i

scheduled for engineering assessment:

• Average grab working level measurement greater than 0.033 'a1.

• long-term working level measurement greater than 0.015 '41.

• Gaana dose rate greater than 20 uR/hr above background.

• Radium-226 concentration in soil greater than 5 pCi/g.

During engineering assessment, extensive gamma surveys, soil core analyses, and/or bore hole logging will be conducted to establish the extent of the contamination by residual radioactivity and the remedial action required.

If it is found during engineering assessment that the elevated radiatica levels are not due to residual radioactivity, no remedial action wi u be taken.

1 10-

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I.

OUTLINE OF PROCEDURE FOR MEASUREMENT OF RADON CAUGHTERS (UL) WITHIN STRUCTURIS Criterion: 40 CTR 192 proposed that the average annual indoor radon decay product concentration including background not exceed 0.015 working level (WL).

This procedure and those which follow were developed for the NRC and the State of South Dakota to conform to the protocols developed and recom-mended by HUD, Region 8. and EPA /8.7 I

i To determine if a structure qualifies for remedial action on the basis of the above criterion, the fonowing procedure is followed to measure indoor rados daughter concentrations expressed as working levels:

1.

Measurement of working level is made in the main living area of the main floor. Should a habitable basement be present, an additional determination of working level is made there. The house is to be closed for a =4n4== of three hours and preferably eight hours prior i

to sampling. Closed means windows, doors, outside vents closed.

2.

For each measurement, an at sample is drawn through a 47 mm Mini-pico type AA filter having a pore size of 0.8 microns at a flowrate cf about 30 to 50 liters per minute for a minN= of five minutes.

3.

Beginning less than seven minutes after the beginning of sampling, the filter (which was counted prior to sampling for background corrections) is counted for a period of three minutes, followed by two ten-minute counts which begin in the intervals 8-1/2 to 12 minutes and 19 to 30 minutes after the beginning of sampling.

4.

The filter is counted by being placed in the close proximity to a zinc sulfide scinti nator covering the entire face of a 5" diameter photomultiplier tube. Counting time is controlled by an electronic timer. Counts are stored in electronic scalars.

5.

Radon daughter concentration ratios are calculated 7:o anow estimation

(

of the air " turnover time" in the house. ' Sho~1d 't turnover time be less ttsn 32 minutes' indicating that the m has not been suffi-

_ ciently tightly sealed and/or that excessive plate-out of radon daughters on surfaces has occurred, the working level measurement is rescheduled for a later date.

6.

Working levels are calculated using the general form of the methods presented by J. S. Thomas (Health Physics,1972) with variable time intervals indicated above.

)Latter from J. R. Giedt, EPA to J. Endres, HUD, August 5, 1980, and letter from J. Martin, NRC/NMSS to G. Hannon, HUD, September 12, 1980.

0)Morken, D. A., University of Rochester, AEC Report No. UR-669, 1966.

') Forty minutes was the turnover time criterion used on some early surveys until more data collected indicated 32 minutes to be a more proper cut point.,

7.

The following decision levels are used to determine which branch of the flow diagram (Figure 1) describes the action to be taken for this structure:

4 a.

If the measurement is less than 0.01 WL for the structure, no engineering assessment nor remedial action is needed unless re-quired because of failure of other criteria (i.e., gamma dose rate >20 uR/hr above background, 22sRa concentration in soil

>5 pCi/g.

b.

If the measured working level is greater than 0.033 on either floor, a second sampling is scheduled for a later date for corrobor-ation. The valid measurements taken on each floor during the initial survey and during any repeat surveys are averaged floor by floor.

(This is necessary since there may be more valid measurements available for one floor than for another.) The structure average is calculated as the average of floor averages.

If the structure average is greater than 0.033 WL, the structure is considered to fail the working level criterion and is scheduled for engineering assessment to define remedial action required.

c.

If the initial average working level measurement or the structure average measurement is between 0.01 and 0.033 WL, it falls in the category requiring long tenn radon progeny measurements to clearly define whether the working level is above or below the 0.015 WL criterion (See Procedure V). However, long term radon progeny measurements are not perfonned on any structure which has failed either of the other criteria mentioned in 7a above.

d l

. a.

I

l II.

OUTLINE OF PROCEDURE FOR GAMMA RADIATION SURVET '4ITHIN STRUCTURES Criterion: 40 CTR 192 proposes that ga:mna radiation greater than 20 uR/hr above background caused by residual rad:.oscrivity result in the removal of said residual radioactivity through remedial action.

To insure the location and removal of residual radioactivity used in con-struction of, or otherwis a carried into the structure, the following pro-cedure for indoor gasuna a urveys is followed:

A.

Backaround Determination The EPA has determined the gamma dose rate background for Edgemont to have an upper limit of 14.5 uR/hr.

'Je use 14.5 uR/hr as the mmvimm background correction to be applied to our survey readings. An alter-nate procedure which could be used is to accept as background average gsumma survey measurements taken in houses in the vicinity of the house being surveyed provided that no high gamma reading ancamites were found in the " background houses" and provided the 14.5 uR/hr EPA desig-nated background value has not been exceeded. A similar procedure is used for residential lots and open lots or lands.

3.

Habitable Area 1.

Room dimensions of all habitable floors and basements in each struc-ture are measured and the room dimensions, sketched on the ganna survey f9rm.

2.

Ganuma measurements are made using Ludlum scintillometer (nicro-R-mater) survey instruments which are at least once daily compared to a emiihrated Reuter-Stokes pressurized ionization chamber Model S-111. (PIC). Calibration data 2nd corrected survey maa-surements are recorded on the gamma survey sketch.

3.

Measursments are made with the survey instrument in the slow re-sponse (long-time constant) mode held at an elevation of about 3 feet. Readings in each room are corrected and recorded at the wall and at all grid points which are about 5 feet apart. This provides for one measurement for approximately each 25 square feet.

h dings are not recorded until the meter needle has stabilized for a few seconds.

4.

The following decision levels are used to determine which branch of the flow diagram (Figure 1) this structure vill follow:

a.

If all r== dings are lese than 14.5 UR/hr including background (indoor background is generally 10-12 uR/hr) at an elevation of about 3 feet, this criterion is satisfied and no engineer-ing assessment nor r===A4=1 action is required unless required because of failure of other criteria (i.e., indoor grab >0.033

'4L, annual average ~4L >0.015, outdoor gamma dose rate

10) EPA Technical Note CRP/L780-2, February, 1980.

3.

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>20 uR/hr above background, and/or soil Ra concentration

>5 pci/g).

b.

If any reading is greater than 14.5 uR/hr including back-ground at an elevation of about 3 feet, surfaces.in the immediate vicinity are surveyed by making contact readings to determine if there is a ganna anomaly.

c.

If the surface readings are all less than 20 uR/hr above background at contact, then once again this criterion is satisfied and no engineering assessment nor remedial action are indicated unless required because of failure of the other criteria mentioned under 4a above.

d.

If any surface measurement is greater than or equal to 20 uR/hr above background at contact, then engineering assessment is required to define necessary remedial action.

C.

Accessible Non-habitable Areas 1.

Garages and non-habitable basements are surveyed using the same Ludlum instruments in the fast response (short time constant) mcde.

2.

A slow walk through procedure is used ;n which an approximate grid or serpentine pattern is followed with brief stops to allcw meter movement to minimize for the readings.

Estimated averages and maximum readings are recorded.

3.

The following decision levels are used to determine whicn branch of the flow diagram (Figure 1) this. structure will folicw:

a.

If all. readings are less than 14.5 uR/hr including background at an elevaticn of about 3 feet, this criterion is satisfied and no engineering assessment nor remedial action are indicated.

i b.

If any readings are greater than 14.5 uR/hr including back-ground at 3 feet elevation are four.d, the procedure outlined under 46, c, and d above is followed.

hb.

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III. OUTLINE OF PROCEDURE FOR GAMMA RADIATION SURVEY OF LOT CONTAINING STRUCTURE Criteria: 40 CFR 192 proposes that gama radiation greater than 20 uR/

hr above background caused by residual radioactivity requires remedial action to remove the residual radioactivity. Also, the average concentration of 22sRa attributable to rasidual radioactivity in any 5 cm-thickness of soils within one foot of the surface, or in any 15-cm thickness below one foot, shall not exceed 5 pCi/g.

To determine if a lot qualifies for remedial action on the basis of the above criteria, the following procedure is followed to located and mea-sure gama =-=H es.

1.

The lot and structures are meas tred and sketched on the gamma survey sheet. The lot is divided into survey blocks of 50 square feet us-ing paced grid lines separated by about 7 feet.

2.

Gama measurements are made uaing Ludium survey meters described in Procedure II.

These meters are compared to the calibrated Reuter-Stokes PIC at least once daily at outdoor survey locations. Cali-bration data and corrected survey measurements are recorded on the gamma survey sketch sheet. The PIC is compared to a gamma source once a day.

3.

c4=== readings are recorded at an elevation of about 3 feet at the estimated grid intersections. Meters are in slow response mode, and corrected readings are recorded only after meter needle has stabilized for a few seconds.

4.

The following decision levels are used to determine which branch of the flow diagram (Figure 1) describes the action to be taken for this lot:

a.

If all readings are less than 14.5 UR/hr including background 11 at an elevation of about 3 feet, surface soil g"ab samples are taken at or near the two survey blocks haviag the highest gamma readings. In the event that it is impractical to collect surfa:e samples at a point of==vimum reading (e.g., becausc of the presence of valuable shrubs or pavement), an alternate locacica showing a high reading is sampled.

If the 2:sRa concentration is less than 5 pC1/g, no engineering assessment nor remedial sction is needed unless required becausa cf failure of other criteria (i.e., indoor grab >0.033 WL, an-nual average WL >0.015, indoor gamma dose rate >20 uR/hr above background).

If the 22sRa concentration is equal to or. greater than 5 pC1/g, engineering assessment to define remedial action required is necassary. These samples are then sent to our Richland, WA

11) See Procedure 7I, Soil Sampling.

12) In the case of a lot which is larger than about 1 acre, containing a struc-ture, the land contained within 50 feet from the struerure will be surveyed using tbis procedure. The rammim'er of the lot will be surveyed using the procedure for open lands (Procedure IV).

laboratory for gemma analysis by intrinsic germanium and/or GeLi spectrometry.

b.

If any gamma readings are greater than 14.5 uR/hr including background at an elevation of about 3 feet, the ground in the inmediate vicinity is surveyed by taking contact readings at the surface to determine if a gamma anomaly exists.

If con-sistent gamma readings above 14.5 uR/hr are observed at about 3 feet, and no gamma anomalies are observed during the first two surface surveys, no more surface surveys are taken unless the i

reading at about 3 feet shows an increase of 1 uR/hr, or more.

c.

If the surface readings are all less than 20 uR/hr above back-ground at contact, soil samples are collected at in Section 4a.

No engineering assessment is indicated unless required because of failure of the criteria mentioned in 4a above.

d.

If any surface reading is equal to or greater than 20 uR/hr above background, engineering assessment is indicated.

In addition, a surface soil sample and a core sample are taken. These soil sam-ples are analyzed for 228Ra as described in 4a above.

i l

e 16

IV. OUTLINE OF PRCCE'ARE FOR GAEA RADIATICN SURVEY OF OPEN L*-NDS Criteria: 40 CFR Ig2 proposes that garra radia: ten greater : nan 20 uR/hr acove background caused by resicual racicactivity requires recedial acticn to remove the resicual racicactivity. Also, ne average concentration of 2 'Ra attributacle to residual radioactivity in any 5 c= thickness of soils winin i foot of the sur' ace, or in any 15 cm :nickness belcw I foot, shall not exceed 5 pCi/g.

To determine if a lot qualf fies for remedial action en :ne basis of the above criteria, the folicwing precedures are follcwed to locate and measure gama ancmalies:

1.

The lot is measured and sketened en a garra survey shee: unless an accropriate plat map is availacie. By pacing er =easuring, ne ic:

is divided into survey blocks by dividing the secrt sice into a col-tzris and tne lcrg sice into 5 r:ws. More rows and/or colu ns are acded if needed to keen :ne survey block dimensicns :: less than 200 fee: cn any sica. At least 20 measurements are =ade en eacn :reperty.

2.

Ga ra tasurements are =ade using Lucl: : survey meters cescribec in Procedure II. These meters are cxcared to ne calibra:ec Reu*er-Stekes PIC at eacn 10:. Calibraticn data anc c:r ec:ec survey reasure-ments are recorded on the ga:r:a survey sheet.

3.

Ga:ra readings are recorded at an elevaticn of abcut 3 fee at the approximate center of eacn survey block. Meters are in slew rescense ocde and the reacings are cer ected and rec:rded cnly after :ne reter needle has stacili:ed for a few sec0nds. As each r:w (coizn) of =ea-surements is c =cleted, the =etar is switched to fast res:cnse :cce, anc a serpentine walk thrcugn survey is =ade of :ne r w (cclu:rt) just surveyed.

The following(Figure 1) describes the acticn to be taken for :nis lot.

4 decision levels are used to determine wnich branen of :ne flew diagram a.

If all readings are 1ess than 14.5 uR/hr including background at an elevatien of abcut 3 feet, a surface soil sa=cle it taken fr:=

the survey bicek having the highes: garr:a reacing."

i If the ::'Ra c ncentraticn ir the soil is less nan 5 :Cf/g (:nea-l surec according to. Precedce VI), no engineering assessment nce re-l medial action are needd.

If the 2"Ra c:ncentra:icn is ecual ::

l or greater than 5 ;Cf/g, engineering assessment is recuirec.

b.

If any garr.a readings are greater than 14.5 :.R/hr including :ack-ground at an elevation of abcut 3 feet, the grcunc in =e i:oedi-ate vicinity is surveyec by taking centact readings 3: :::e sur-face to deterzine if a garra ancmaly exists.

If censisten: garra reacings above 14.5 uR/hr are c: served a: ateu: 3 feet, anc no ;a.a

13. See :-Ocecure VI, Soil Sarsiing 17

anc:nalies are c:: served during :ne firs: 0.c sur ace surveys, no :cre e

surface surveys are taken unless One reacing at a: cut 3 feet sncas an increase of 1 ?./hr or ecre.

c.

If the sur# ace reqdings are all less than 20 tR/hr abcVe tack-grcund at contact, one sur' ace soil saccle is collectec in :ne block having tne hignest ca:mra reading. No engineering assess:wtn:

is indicated unless the 2:sRa concentration in :ne scii sa:cles exceeds 5 ;:Cf/g.

d.

If any sur# ace reading is equal to or greater :.an 20 2R/br abova background of 14.5 uR/hr, engineering assessant is required.

In addition, a sur# ace scil sam::le and a c:re sa:cle are taken. These soil sam;:les are analy:ed for 2 'Ra.

e er d

P 18

V.

QUTLINE OF PROCECURE FOR LONG-TERM RADON CAUGHTER (WL) MEASUREMENTS WITHIN STRUCTURES Criterion: 40 CFR 192 proposes that the average annual indoor radon decay product concentration including background not ex-ceed 0.015 working level (WL).

Confinnation of the grab sample measurements (ProcedureI) deternined to be between 0.01 to 0.033 WL will be perfonned by the following method.

Long-tenn radon daughter measurements are not made if the structure is already slated for engineering assessment due to failure of another cri-terion (i.e., 22sRa concentration >5 pC1/g, gamma dose rate >20 uR/hr above background).

1.

Integrated working level measurements are made for ncminal sampling times of 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> every other month for a period of one year. This yieloa six sample results to be averaged to approximate the average annual indoor radon decay product concentration.

2.

The measurements are made using Radon Progeny Integrating Samoling Units (RPISU) provided and calibrated by the EPA, Las Vr. gas facility.

Measurements by other methods, such as repeated grab varking level measurements and track etch, will be compared to the APISU measure-ments to deternine whether a simpler method than the RFISU can be used.

3.

If the running time meter indicates the unit shut down before 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> had elapsed, the measurements will be repeated.

4.

Measur?ments are made, if possible, in the main living area or habit-able basement.

If high dust or snoke levels in these locations regu-larly plug the RPISU filter before 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />, measuremants =ay be made in a more remote location, such as a bc< room.

5.

If the average measurement is less than 0.015 WL, the criterion is satisfied and no renedial action is necessary.

6.

If the average measurement is equal to or greater than 0.015 WL,

_ engineering assessment to define re.acial action required is necessary.

4 a r

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VI. OUTLINE OF PROCEDURES FOR SOIL SAMPLING AND ANALYSIS Criterion: 40 CFR 192 proposes that the average concentration of 22sRa attributable to residual radioactivity in any 5-cm thickness of soils witnin one foot of the surface, or in any 15-cm thickness below one foot, shall not exceed 5 pCi/g.

When required by the Procedures III Ganna Radiation Survey of Lot Containing Structure and IV Gamma Radiation Survey of nren Lands, the following procedure A has been used which is noir being modified to Procedure B.

All soil samples are archived at PNL.

A.

Original Sampling Procedure 1.

Surface Samples a.

Surface soil samples were taken with a slightly concave, flat-edged spade with a 6-inch wide blade. The spade was forced into the ground at an angle which would yield a sample about 6 inches wide by 3 inches deep by 4 inches long.

b.

The sample was homogenized, weighed, and transferred into a metal can (approximately 410 mi capacity) and sealed with a manually operated can sealer. Cans were checked for leaks by innersion in nearly boiling water and inspection for bubbling.

l 2.

Core Samples l

a.

Core soil samples were taken with a 1-1/2 inch diameter soil-split tube core sampler. The sampler was driven into the soil to a depth of about 18 inches, retrieved, and opened.

b.

The soil was homogenized, weighed, and as much sample as pos-sible was transferred into a metal can (approximately 410 ml capacity) and sealed with a manually operated can sealer.

Cans we.e then checked for leaks.

Br New Samo!.nq Procedure 1.

F:.cface Samples l

a.

Surface soil samoles are taken using a sampling device which 2

~

samples a 200 cm area to a depth of 5 cm. The device is driven into the ground at the sampling spot. A small trench is dug next to each end of the sampler (preserving any grass sod removed for later replacement) to allcw guillotine-type blades to be inserted into the sampler at 5 cm depth to en-close the bottom of the sample. t

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b.

The sampler containing the snole is removed from the ground, the soil is transferred to a plastic bag, and leaves, grass, and roots are removed from the soil after shaking.

If in-sufficient soil is obtained for analysis, an adjacent sam-ple(s) is (are) combined with the first. The soil sample is homogenized, weighed, and sealed in a metal can having a 410 ml capacity. The can is tested for leaks.

2.

Core Samples a.

Core samples are taken with a 1-1/2 inch diameter split tube core sampler. The sampler is driven into the ground to a depth of about 18 inches, retrieved, and opened.

b.

The top foot of the core is separated into five separate samples (each is approximately 5 c:n in length). The remain-ing 6 inches of core (approximately 15 cm) are left intact.

The six samples are transferred into plastic bags.

~ '

The coring procedure may be repeated at the same sampling c.

spot combining samples from equal depths until enough sample has been collected for counting.

d.

The individual.composited samples are tnen homogenized, weighed, and sealed in metal cans. The cans are checked for leaks.

C.

Procedure for Analysis of Soil for 22sRa 1.

The sealed metal cans are stored for at least ten days prior to counting to allow 222Rn and its short-lived daughter 21*Bi to grow in.

2.

The cans are placed in plastic bags and are counted 10 minutes in a 9-inch diameter x 9-inch deep NaI(Tl) well counter.

(The cans used are the largest that will fit into the well of the detectors.) The gama-ray spectra are stored in a multichannel analyzer.

2 The efficiency of the detector is determined daily by counting a homogenized uranium mill tailings sample whose.2sRa concen-tration has been established by comparison with an NBS 22sRa standard.

4.

The 22sRa concentrations are calculated from the measured 21*Bi concentrations using correction factors for the fractional in-growth of the parent 222Rn at the time of counting.

It is as-sumed that the 222Rn concentrations are 50% o'.~ equilibrium at the time the cans are sealed..

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Procedure for the Determination of the Source of the 22sRa 1.

Soil samples are sent to Pacific Northwest Laboratory at Rich-land, Washington, for archiving.

2.

Samples that have been determined to contain greater than 5 pC1/g of 22sRaareopened, homogenized, dried,andweighed.

A 60 g portion is analy;;a fcr 23 Th (the 24-day daughter of zang),zioTh,22'Ra,and Pb using an intrinsic germanium 21 gansna-ray spectrometer system.

3.

Thoriun-130 and/or 22sRa concentrations that are significantly higher than the 23'Th concentrations are assumed to indicate the presence of uranium mill tailings.

4.

Visual observation by a trained observer of the physical cha -

acteristics of the soil samples and the deposit at the sampling site is also used to indictte whether residual radioactivity is present. The concentrations of 23"Th, zieg, 2:aTh, 22sg, and 218Pb are established by comparison to standards traceaole to NBS.

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Maxinun Indoor.7 Haxinun Indoor 7 Maxinun Outdoord.7Haxinun Outdoor? Haxinun 226pa 2

Pill Property Avera9e Radon Identi fica tion Dau9hter Con-Ganma Dose Ganana Dose Rate Ganana Dose Gansna Dose Rate Concentrations Code centration Rate at Contact Rate

___ at Contact in Soil Working Levels pR/hr pR/hr pR/hr pR/hr pCi/g i

21 0.0318 10 12 1.9 22 0.0256 10 12 3.0 23 0.0364*

10 12 5.5*

24 0.0476*

11 12 2.3 25 0.0149 10 13 2.8 26 0.0260 10 13 3.0 27 0.0319

.11 13 2.9 28 0.0044 7

11 2.7 29 0.08S3*

24 54*

19 40*

77*

30

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11 2.8 31 0.0235 8

11 2.3 32A 0.0057 14 t

328 0.0060 13 7.4*

32C 0.0197 33 0.0039 11 17 24 6.9*

34 0.0206 11 13 3.8 35 RRWL5 13 12 2.6 36 0.0241 10 12 2.0 37 0.0148 11 11 4.0 38 0.0046 10 12 2.2 39 0.0119 11 14 2.8 40 0.0064 12 11 150*

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Maxinuani Outdoor.7 Haxlaussi Outdoor 7 Maxinuun 226Ra d

2 Maxiuman Indoor,7 Maximiuni Indoor 7 PHL Property Average Radon Identification Daughter Con-Ganma Dose Gausna Cose Rate Ganena Dose Gansna Dose Rate Concentration Code centration Rate at Contact Rate at Contact in Soil Working l evels pRfg pR/hr pR/hr pR/hr ECijg 41 0.0097 11 14 16 4.4 42 0.0061 11 13 3.3 43 0.0035 11 15 20 15.7*

44 0.0394*

11 10 2.2 45 0.0024

'9 11 3.2 46 4

9 10 4.3 47 0.0223 10 11 2.5 48 0.0100 10 13 6.3*

49 4

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30 38*

17 130*

489*

Su 0.0161 12 13 2.3 59 0.0460*

11 13 3.3 60 0.0394*

11 13 2.7 j

9

Maxinomi Indoor,7 Maximum Indoor 7 Haximum Outdoor =7PMxinumi Outdoor 7 Maxinaan 226pa 2

3 Pill Property Average Radon Identification Dau9hter Con-Ganssa Dose Gannia Dose Rate Gaamia Dose Gausna Dose Rate Concentratfoa Code centration Rate at Contact Rate at Contact in Soil Working levels pR/hr pR/hr pR/hr pR/hr pCi/g 61 0.0143 11 12 3.0 62 0.0066 10 12 2.9 63 0.0139 10 11 2.9 64 0.0268 11 12 i

4.4 65 0.0158 11 13 3.9 66 0.0160 10 13 3.0 67 0.0264 12 13 3.1 68 0.0076 11 13 3.1 69 0.0335*

10 13 5.4*

70 Vacant Lots 71

'0.0322 12 13 4.1 72 RRWL 12 12 4.1 73 0.0316 12 13 2.6 74 0.0124 12 12 2.2 75 0.0093 10 12 3.3 76A 0.0149 10 18 1 14 20 5.l*

7 611 0.0170 16 16 77 RRWL 12 12 3.4 711A 0.0061 14 16 7 1111 0.0279 12 3.1 79 0.0106 9

12 5.9*

80 0.0270 11 13 5.0 9

Haximum Outdoor.7 Haximum Outdoor 7 Haximum 226Ra 8

2 Maxisiniin Indoor.7 Haxinium Indoor 7 Pill Property Avera9e Radon Dau9 ter Con-Ganma Doce Gansna Dose Rate Ganna Dose Gauma Dose Rate Concentration Identification h

Code centration Rate at Contact Rate at Contact in Soil Working Levels pR/hr pR/hr pR/hr pR/hr pCi/g 81 0.00756 9

Same Lot as #72 82A 0.0004 10 28 900*

1920*

828 0.00536 9

83 0.0190 10 12 3.7 84 Vacant Lots US 0.0144 9

12 2.8 86 0.0085 10 12 3.0 87 0.0314 10 12 2.2 8 11 0.0050 9

12 2.2 89

.0034 11 12 2.7 90A 0.01386 10 12 1.9 908 0.0100 90C RRT0s 91 0.0071 9

12 1.9 92 0.00926 10 12 3.2 93 0.00976 9

14 3.0 94 0.01126 15 16 13 4.1 95 0.0141 10 12 2.1 96 0.0010 9

12 2.1 97 0.0225 11 12 2.6 98 0.0029 18 18 26 26 1.9 99 RRTO 10 12 2.5 BfMT i

Haximum Outdoor.7 Haximum Outdoor 7 Maxinum 226pa d

2 Maximum Indoor,7 Maxlanun Indoor 7 PNL Property Avera9e Radon Identi fication Dau9hter Con-Ganina Dose Gansna Dose Rate Ganana Dose Gansna Dose Rate Concentration Code centration Rate at Contact Rate at Contact in Soil Working Levels pR/hr pR/hr pR/hr pR/hr pCf/g 100 0.0081 10 12 3.0 101 0.0067 9

16 28 8.i*

102 0.1083 9

13 2.4 103' O.0225

'9 12 2.5 104 0.0147 9

12 3.4 105A 0.0185 10 1058 0.0123 106 0.0101 10 11 4.4 107

'0.0100 10 13 4.6 108 0.0034 11 15 19 4.1 109 0:0240 9

11 2.8 110 0.0027 11 11 2.5 111 0.0440*

12 10 Business..No Soil 112 0.0099 13 12 113 0.0127 15 15 10 114 0.0194 10 11 115 0.0222 11 12 3.6 116 0.0266 9

12 2.2 117 0.0178 11 13 2.6 118 0.0157 10 12 119 0.0275 11 20 42*

8.4*

120 0.0018 10 14 22 2.7

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Haximuni Outdoor.7Haxinun Outdoor 7 Maxinun 226pa d

Maximum Indoor.7 Maximum Indoor 7 2

Pill Property Average Radon identi fica tion Daughter Con-Ganina Dose Gansna Dose Rate Gansna Dose Ganna Dose Rate Concentration gde centration Rate at Contact Rate at Contact in Soll Working ievels pR/hr pR/hr pR/hr pR/hr pCl/g 140 0.0064 10 12 1.8 14IA 0.0294 8

1410 RRWL 8

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141D 0.0140 8

g 141E 0.0255 8

141f 0.0212 8

141G 0.0085 8

14 Ill 0.0071 8

j 142 0.0616*6 12 16 7.la 143A 0.0068 14311 0.0014 10 12 2.I 143C 0.0011 143D 0.0036 144 0.0320 12 13 2.6 145 0.0248 14 12 2.3 146A 0.0213 9

2 4'

I 4(30 0.0183 10 147 0.0323 12 12 2.5 148 0.0786*

9 12 3.1 149 0.0284 11 14 23 5.7*

4

Pill Property Average Radon Maxinun Indoor 7 Haximum indoor? Haxinun Outdoor 7 Haxinun Outdoor 7 Maxinun 226Ra 2

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.150E RP.WL 10 150F 0.0308 IO

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Maxinun Outdoor *7 Haxinun Outdoor 7 Maxinuu 22cga J

l'HL Property Avirage Radon hcxtuun Indoor,7 Haximun Indoor 7 2

Identi fica tion Dau9hter Con-Ganana Dose Gaasna Dose Rate Gansna Dose Ganana Dose Rate Concentration Code centration Rate at Contact Rate at Contact in Soil Working Levels pR/hr pR/hr pR/hr.

pR/hr pCi/g 177 0.0374*

11 12 1.4 178 0.0078 9

11 1.9 179 0.0075 16 16 20 2000*

19.5*

180 0.0130 14 12 2.8 181 0.0253

,10 12 2.3 182 0.0083 10 14 3.6 e

183 0.0039 10 13 4.1 184 0.0098 12 12 3.7 185 RRTO 11 20 20 4.2 186 0.0322 11 16 17 3.8 6

187 0.0179 11 19 36*

15*

188 0.0109 14 11 2.5 189 0.'0293 10 11 2.0 190

.0056 11 17 19 11.8*

191 0.0155 11 12 2.2 192 0.0264 10 13 2.6 193 0.0172 10 13 1.4 194 0.0187 12 15 15 2.7 195 Outdoor Only Outdoor Only 16 20 2.1 196 RRWL 16 14 2.4 197 RRWL 16 17 15 15 2.6 198 0.0094 12 12 2.1 199 0.0348*

11 13 2.1 200 0.01706 10 14 14 2.4

\\

PHL Property Average Radon Maxinioni Indoor.7 Maxinun Indoor 7 Haximun Outdoord*7 Haxinun Outdoor 7 Maxiniuni 226pa 2

Identification Daughter Con-Gasma Dose Gaasna Dose Rate Ganuna Dose Ganna Dose Rate Concentratinii Code centration Rate at Contact Rate at Contact in Soft Working Levels pR/hr pR/hr pR/hr pR/hr_

pCi/g

~

201 0.0313 10 13 2.2 i

202 0.0442*

10 12 1.7 4

203 0.0811 10 12 2.4 204 RRTO 11 14 2.2 205 0.0412*

,11 14 2.2 206 0.0293 12 14 2.5 207 0.0240 12 13 2.8 208 0.0080' 11 12 5.1*

209 Vacant Lots 210 0.0113 (a)

(u) 211 0.0105 (a)

(a) 212 0.0081 (8)

(a) 213 0.'0304 (a)

(u) 214 0.0146 12 12 2.3 215 0.0193 12 13 3.5 216 0.0088 11 13 1.7 217 0.0173 13 13 2.6 218 219 0.0223 15 15 16 160*

257*

220A 0.0189 12 21 175*

2.1 2208 0.0165 221 0.0142 14 12 2.8 222 RRTO 20 20 100*

170*

U 1

9

4 (4) lieruns were required because the indoor air turnover time was less than 40 minutes, but not performed because:

• Ikmeowner refused permission

• The croperty was already passed by the state of South Dakota or

• The p.wperty was scheduled for remedial action based on prior surveys (S) RitWL neans wor; ing level measurement is pending rerun because the initial measurement exceeded 0.033 WL.

HRTO neans work'.ng level neasunnent is pendinq rerun because the initial turnover time was below ouricriterion (40 minutes prior to 12/20/80. 32 minutes thereafter)

RRW means working level measurement is pending rerun because the wind speed was greater than 8 aph duri. d the few hours just prior to sangling.

4 (6) A double occurrence of turnover rate below the limit was measured. The result from the saneling with the highest mininnai turnover time was used.

(7) All gansna dose rate measurements are total readings uncorrected for background.

(a) lhe outdoor gansna surveys were not completed in the Cottorwood area because dose rate shine from the adjacent tallings pile precluded evaluation of the exposure rate originating on ahe properties being % veyed.

e i

)

PNL Property

.virage Radon Aximum Indoor.7 Nxlinusii Indoor 7 Nximium Outdoor'*7 Nximiusi Outdoor 7 Nximum 22cp, 2

Identi fication Dw ghter Con-Ganana Dose Gamuna Dose Rate Gaauna Dose Ganana Dose Rate Concentra tion Code centration Rate at Contact Rate at Contact in Soil Working Levels pR/hr iiR/hr pR/hr pR/hr pCl/g 223 0.0119 11 19 24 224 0.0082 11 12 225 0.0007" 12 14 226 RRWL 11 12 227 0.0011

,13 85*

92*

228 RRWL 10 12 229 0.0168 10 11 230 RRTO 10 11 231 RRWL 11 19 19 232 0.0182 11 12 233 0.0093 11 11 214 235 236 237 238 239 l

240 (II Asterisks *ndicate levels which qualify the property for engineering assessment.

(2) Indoor gannua dose rate measurements (not corrected for background) madeholding the scintillometer about three feet above the ground.

(3) Outdoor gansna dose rate measurements (not corrected for background) made holding the scintillometer about three feet above the ground.

DRAi:

.