&ER& United Slates Environmental Protection Agency Office of Radiation Programs Eastern Environmental Radiation Facility 1890 Federal Drive Montgomery, AL 36109 EPA 520/5-87-005 June 1987 Radiation EERF Standard Operating Procedures for Rn-222 Measurement Using Charcoal Canisters ------- EPA 520/5-87-005 EERF STANDARD OPERATING PROCEDURES FOR RADON-222 MEASUREMENT USING CHARCOAL CANISTERS David J. Gray Sam T. Wtndham March 1987 U.S. Environmental Protection Agency Office of Radiation Programs Eastern Environmental Radiation Facility 1890 Federal Drive Montgomery, Alabama 36109 ------- EERF Standard Operating Procedures for Radon-222 Measurement Using Charcoal Canisters I. Introduction Activated charcoal has a large affinity for several gases and vapors including radon-222 (hereafter referred to as radon). Radon Is sorbed onto the charcoal grains and decays to several participate decay products: radium A (polonium-218); radium B (lead-214); radium C (blsmuth-214); radiunrC1 (polonlum-214); and radium 0 (lead-210). Radon concentration Is determined by counting the gamna ray emissions of both lead-214 (295 KeY and 352 KeY) and bismuth-214 (609 KeY). This Is possible due to the relatively short half-life of these progeny. Within 3 hours the progeny are In equilibrium with radon-222. The passive nature of activated charcoal allows both adsorption and desorption, and, in addition, the adsorbed radon undergoes radioactive decay during the exposure period. Therefore, the canister cannot uniformly Integrate over the entire exposure period. However, the canisters can be calibrated to yield precise results for radon concentrations In structures during the deployment period of 48 hours used by the U.S. Environmental Protection Agency (EPA). The charcoal adsorption method has been reviewed extensively by Cohen (Co83, Co86), Prichard (Pr85), and George (Ge84). The EPA's canister and analysis technique most closely resemble George's work, differing only In calibration aspects. ------- II. Materials and Equipment A. Charcoal Canister The passive radon charcoal canister used by the EPA consists of the following materials: (1) 8 ounce metal can with I1d (4 Inch diameter by 1 1/8 Inch deep); (2) 70 ^ 1 grams of 6 X 16 mesh activated charcoal; (3) metal screen, with an openness of at least 30 to SO percent; (4) removable, Internally expanding retaining ring; (5) pad material attached to the Inner surface of the lid; and (6) a 13 Inch strip of pliant vinyl tape. The materials are assembled as seen In Figure 1. The activated charcoal must have low radioactivity content. Specifically, gamma emitters, except for natural potasslum-40, must be less than 0.1 plcocurles per gram. B. Counting System The following components make up the counting system used by the EPA's Eastern Environmental Radiation Facility: (1) 3' by 3" sodium-Iodide detector and photomultlpller tube Inside counting shield; (2) high voltage power supply; (3) pre-amplifier and amplifier; (4) single channel analyzer and sealer; (5) timer; (6) time of day clock; and (7) printer. ------- Pad attached to lid to retain screen during shipping X Internal expanding stainless steel retainer ring 8 ounce metal can 13" strip of vinyl tape Stainless steel screen, 30-50 percent open 70 + 1 grams of 6 i 16 mesh charcoal FIGURE 1 Charcoal canister assembly ------- Four sodium fodlde detectors are served by a single high voltage power supply, timer, printer, and time of day clock. Each detector has Its own pre-ampllfler, amplifier-single channel analyzer, and sealer. The four detectors are arranged together Inside a shield that has steel walls 8 Inches thick. Within the shield the detectors are separated from each other by 4 Inches of lead. A wooden jig Is used on each detector to assure consistent counting geometry for the canisters on the detector. The arrangement of detectors In the shield and the electronics are shown In Figures 2 and 3. The counting system is operated in the single channel mode with a lower discriminator setting of 270 KeV and an upper discriminator setting of 720 KeV. All counts in this region are summed during the counting period. A multi-channel analyzer is used once a week to assure there has been no shift of the peaks In the region of interest. C. Radon Calibration Chamber The EERF uses 2 radon calibration chambers to expose charcoal canisters and* other instruments to known concentrations of radon and radon decay products in controlled environmental conditions. Radium-226 sources are used to provide radon which 1s continuously flowed through the chambers. In the chamber, controlled conditions include relative humidity (10 to 90 percent), temperature (0* to 40*C), condensation nuclei (10 to 106/ml), radon concentration (10 to 1,000 plcocuries per liter (pCI/liter), and radon decay product concentration or working level (WL) (0.01 to 5 WL). ------- FIGURE 2 Four detectors 1n counting shield ------- FIGURE 3 Two shields with electronics ------- The temperature, tumidity, radon concentration, radon decay product concentration, and condensation nuclei concentration are monitored continuously and printed out each hour. Radon concentrations are monitored using a 0.5 liter flow through scintillation cell and decay product concentrations are monitored by counting, with a surface barrier detector, the alpha activity from decay products collected on a filter. Grab samples in conjunction with the hourly printouts are used to determine radon and decay product concentrations in the chambers. The grab samples, which are done In conformance with recently published EPA procedures (EPA86), are used to calibrate the hourly printouts. 0. Standard and Background Canisters Counting system performance Is determined daily by counting standard canisters containing known radioactivity and background canisters. The standard canisters were made by the quality assurance group at the EERF In the following manner: (1) a known activity of about 20.5 nd, liquid radium-226 was slurried into the 70 grams of charcoal in a canister with the retainer screen removed; (2) this was heated to dry all liquid from the charcoal; (3) the canister was sealed by soldering a galvinized metal disc in the can where the screen normally is located; (4) the lid was placed on the canister and secured with tape; and (5) the standard was stored for thirty days to allow secular equilibrium to be reached between the radium, the radon, and the progeny. Standard and background canisters were prepared for each crystal and are counted every morning to establish ------- a dally counting efficiency for each detector systea. The counting efficiency Is determined by counting the standard and background canisters each for 10 minutes. The background count Is subtracted from the standard count to get the net count. This Is divided by the tine, 10 mfnutes, to get net counts per minute (CPM). By dividing the net CPU by the known activity (pd) of the standard the efficiency (CPM/pCI) of the detector for that day 1s determined. E. Scales Digital scales are used to weigh individual canisters both before shipment to the user and upon receipt after exposure. This weight difference, which relates to moisture gain or humidity, Is an integral part of the calculation of radon concentration and will be explained In greater detail in the next section. Canisters are weighed to 0.1 gram accuracy. 8 ------- III. Laboratory Methods A. Canister Preparation Calibrations are run on representative samples of canisters from each new batch from a supplier. As required by the EPA purchase contract, the supplier identifies each batch by the color of the vinyl tape used to seal the lid. Gamma emitter content of the charocal is also checked for each batch to make sure no contaminated charcoal 1s being used. Each canister Is given an individual serial number. This number Is printed on the data label attached to the top of each canister. Once this label is attached, the canister is weighed and the weight 1s written on the label and is automatically entered into the EERF computer for that respective canister serial number. The canister Is now ready to use for calibration runs or In a home for a radon measurement. B. Calibration The response of charcoal canisters depends on the length of time the canister is exposed and on the amount of water gained during the exposure. This is because the charcoal has a strong tendency to adsorb water from air. For this reason the canister calibration Is a two step process designed to adjust for both water gain and exposure time. The following steps are used to calibrate canisters: ------- 1. Chamber Preparation The charcoal canisters are calibrated to three timidity ranges (low, medium, and high) over a period of one to six days. Low, medium, and high humidity correspond approximately to 20, 50, and 80 percent humidity. The radon concentration In the chamber 1s kept as constant as possible during the three runs. The first step of this process, therefore, entails stabilizing the chamber at the desired condition. 2. Canister Exposure Sequence When the chamber Is stabilized, a set of 30 canisters Is put Into the chamber and exposed In the following manner: a group of five each for 1, 2, 3, 4, 5, and 6 days, respectively. The canisters are opened Inside the chamber and the exact start times are recorded. This exposure sequence Is repeated twice more, once at each of the other two hualditles, to complete the calibration run. 3. Removal and Counting At the end of each 1 day period specified above, a group of 5 canisters 1s removed for counting. The lids are placed on the canister while still Inside the chamber and the canisters are reooved, taped, and the exact time Is recorded. The canisters are allowed to sit for at least 3 hours to allow progeny to equilibrate with the radon before counting. 10 ------- Each canister 1s counted for ten minutes on a sodium-Iodide detectors described previously. The count time and detector number are recorded so that the efficiency of that detector, from previous counting of standard and background, can be Incorporated In the calculation of calibration factors. After counting, the canisters are weighed and the weight difference Is recorded. 4. Calculation of Calibration Factors A calibration factor 1s calculated for each canister using the following equation: CF _ NET CPU (Equation 1) (Ge84) (Ts) (E) (RN) (OF) where CF = Calibration factor, radon adsorption rate (1/mln), NET CPH = Gross CPM for that canister - background CPM for that detector for that day, T = Exposure time of the canister (minutes), E = Detector efficiency for the appropriate detector (CPM/pCI), RN = Radon concentration 1n the chamber for the exposure period (pCI/llter), OF = Decay factor from the midpoint of exposure to the time of counting, which Is calculated from .693t .693t DF = e' T » i«*-\ or e 'w» R« (min) c 5501 mln i/t n where t = time 1n minutes from midpoint of exposure to the start of counting. 11 ------- 5. Generation of Calibration Curves Calibration factors as derived from the equation above are used to generate two tables and two curves. The first table, Table 1, relates calibration factor to weight gain (water) for the canisters for a 2 day exposure, the time used by EPA for Its surveys (see IV 0). Data 1n this table are plotted to generate Figure 4. The second table, Table 2, relates exposure time to adjustment factors for 20, 50, and 80 percent humidity. The adjustment factor Is used to modify the calibration factor for exposure times different from the desired 2 day exposure time. If a canister Is exposed for exactly 2 days, the adjustment factor Is 1. This 1s explained In more detail In III C 5. Data In this table are plotted to generate Figure 5. Figures 4 and 5 are typical calibration data that were developed for a particular batch of canisters from a supplier. New calibration data are developed and used with each different lot of canisters. C. Calculation of Radon 1n an Exposed Canister Equation 1 above nay be rearranged to solve for the radon concentration If the calibration factor Is known. This equation will be RN , MET CPH (Equation 2) (Ts) (E) (CF) (DF) 12 ------- where RN » Radon concentration In pCI/llter, NET CPM = Gross CPM for the canister - background CPN for that detector for that day, T * = Canister exposure time (minutes), E = Detector efficiency (CPM/pCI), CF = Calibration factor, and OF = Decay factor from the midpoint of exposure to the start of counting. Table 1 Water Gain Versus Calibration Factors For a 2 Day Exposure Percent Humidity Water Gain (g) CF (I1ter/m1n) 20 20 20 20 20 50 50 50 50 50 80 80 80 80 80 0.0 0.0 0.0 0.0 0.0 1.7 1.8 1.9 1.8 1.8 7.7 7.5 7.7 7.9 7.9 0.105 0.101 0.105 0.110 0.107 0.098 0.094 0.097 0.102 0.096 0.077 0.082 0.076 0.076 0.078 13 ------- Table 2 Exposure Time Versus Adjustment Factors for Low. Medium, and High Humidity Time of Exposure (Hours) 24 24 24 24 24 48 48 48 48 48 72 72 72 72 72 96 96 96 96 96 120 120 120 120 120 144 144 144 144 Adjustment Factors 20 Percent 0.137 0.143 0.141 0.135 0.138 0.107 0.110 0.105 0.101 0.105 0.087 0.091 0.088 0.083 0.085 0.074 0.080 0.075 0.074 0.075 0.070 0.073 0.071 0.069 0.071 0.064 0.068 0.064 0.062 50 Percent 0.132 0.137 0.132 0.126 0.127 0.096 0.102 0.097 0.094 0.098 0.075 0.079 0.075 0.073 0.075 0.058 0.062 0.059 0.057 0.060 0.051 0.054 0.051 0.050 0.052 0.045 0.047 0.047 0.044 (llter/mln) 80 Percent 0.116 0.125 0.118 0.117 0.118 0.077 0.082 0.076 0.076 0.078 0.048 0.051 0.051 0.046 0.049 0.035 0.034 0.033 0.033 0.034 0.023 0.025 0.024 0.023 0.023 0.018 0.019 0.016 0.018 14 ------- FIGURE 4. WATER GAIN VERSUS CALIBRATION FACTORS (CF) FOR A TWO DAY EXPOSURE -«- -- :&::::::»......! ********* a*** --«»«** »-_. -**«« *-. ^ .04- .02' I 0 2.0 4.0 6.0 8.0 I 10.0 12.0 14.0 160 1 18.0 Water Gain (g) ------- Figure 5. EXPOSURE TIME VERSUS ADJUSTMENT FACTORS (AF) FOR LOW, MEDIUM, AND HIGH HUMIDITY .14 .12 .10 .06 .06 .04 .02 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 Exposure Time (Hours) ------- The following steps are taken to analyze the canister and calculate the radon concentration to which a canister has been exposed: 1. Count the standard canister on the detector to be used. Calculate the efficiency (E) for that detector 1n CPM/pCI as In section II-D. This efficiency Is used for all counting done on that detector for that day. 2. Count the background canister on the detector. This background count Is used for all counting done on that detector for that day. 3. Weigh the canister to be analyzed. This weight gain In grams of water during the exposure period Is referred to as (g) In Table 1 and Figure 4. 4. Use the water gain (g) on the X-axis on Figure 4 to obtain an Initial CF from the Y-axis. 5. If an exposure period other than 48 hours was used, this Initial CF must be adjusted to reflect the actual exposure time for the canister. This Is done by using the water gain to select the appropriate humidity curve on Figure 5. The correct humidity curve Is selected based on the following criteria: If (g) Is Use Curve for less than 1.0 g 20 percent 1.0 g to 4.0 g 50 percent greater than 4.0 g 80 percent 17 ------- Using the correct water gain on the X-axis and relative humidity curve on Figure 5, an adjustment factor (AF) Is selected from the Y-axis and used to adjust the Initial CF (obtained In step 4 above) for the exposure time. This Is done as follows: Final CF used in Eq. 2 = Initial CF X AF for actual exposure time AF for 2 day (48 hr) exposure time From this it is seen that If the actual exposure time 1s 48 hours the AF becomes 1.0 and the initial CF Is actually the 'CF used In Equation 2. 6. The decay factor (OF) Is used to correct for radiological decay between exposure and counting. It Is calculated from the midpoint of exposure to the start of counting using the formula .693t OF = 6 ^1/2 ^or rad°n where t is the tine from midpoint of exposure to the start of counting and T. iy Is the half-life of radon. EXAMPLE CALCULATION To calculate the concentration of radon in a canister we use Equation 2, RM= NET CPH (Ts) (E) (CF) (OF) 18 ------- The data gfven for this example calculation are the following: Weight Out 158.7 g Weight In » 161.1 g Exposure Period = 12-29-86 at 1052 CST to 01-01-87 at 0950 CST Gross Counts = 2,942 in 10 minutes Background Counts = 721 in 10 minutes Standard Counts = 58,423 in 10 minutes for a 20,549 pCI source From these data, we first determine that Net CPM = - 721 = 222 CPM 10 min. T = 70 hours, 58 minutes = 4258 minutes, and E = (58.423 - 72D/10 minutes = 0.281 CPM/pCi. 20,549 pCi To determine the calibration factor (CF), we must refer to the equation CF , Initial CF X AF for exposure time AF for 2 day (48 hours) and use the weight gain in our calculations. In this example, the weight gain during exposure was 2.4 g (161.1 g - 158.7 g). From Figure 4, we find that the initial CF for 2.4 g - 0.094; and, according to Figure 5, 19 ------- a 2.4 9 weight gain requires the use of the curve for SO percent humidity. Since a 2.4 g weight gain of 50 percent humidity results 1n an AF for the actual exposure time (~ 71 hours) of 0.080 and an AT for 48 hours of 0.098, the final CF Is 0.077, as calculated by final CF = 0.094 X °'080 = 0.077 . 0.098 The decay factor for Equation 2 Is calculated by .693t DF ^ where t = midpoint of exposure time to start of counting time, 2 = 6,441 minutes, and Tj ,2 of radon = 3.82 days or 5,501 minutes. The decay factor then Is calculated by (.693) (6,441) OF = e~ » 5,501 = 0.444. 20 ------- The final radon concentration Is calculated by substituting the above values Into Equation 2 as follows: 222 RN = (4258) (0.281) (0.077) (0.444) = 5.4 pCi/liter. The 2-sigma counting error Is calculated as follows: 2o.error = 2 YGross counts * Background Counts Gross counts - Background Counts 2o error = 2 V2.942 * 721 § 2,942 - 721 = .054. = 5.4 percent. Therefore, the radon concentration was 5.4 pC1/liter ^ 5.4 percent. D. Calculation of Minimum Detectable Activity The minimum detectable activity (MDA) for measuring radon using charcoal canisters 1s a function of the background counting rate of the counter system and the counting time (A163). The MDA at the 3-sigma significance level Is given by HDA . 3 X V BKG Count Time 21 ------- where MDA = MOA as function of counts above background, BKG Count = Total background counts, and BKG Count Time = Counting time of background. For the ECRF counting system, this calculates as r750" MDA (CPU) = 3 X , 10 = 8.2 counts per minute. This may be converted to activity of radon In pd/llter by assuming exposure conditions. For our desired exposure conditions, this calculates as follows: Assumed conditions: Exposure time = 2 days (48 hours) Relative humidity - 50 percent (2 gram water gain) Time in shipment = 3 days (4,320 minutes) Counter efficiency = 0.28 CPM/pCi MDA (CPM) =8.2 (from above) MDA (CPH) MOA (pd/llter) = (Exposure Tfme) (E) (CF) (DF) 8.2 (2.880) (0.28) (.098) (.48) = 0.22 pd/llter Since assumed conditions are not always met, In EERF data reports the MDA Is conservatively reported as less than 0.5 pC1/liter. 22 ------- E. Quality Assurance Procedures The EERF radon calibration chambers are the principal source of quality assurance exposures for charcoal canisters. After the Initial calibration run on each new batch of canisters from a supplier, periodic checks are made on randomly selected canisters to assure no deviation. Reliability of the EERF calibration chambers Is assured through several programs. As described previously, the chamber Is monitored continuously while In operation. Also, dally checks on the radon and t radon decay product concentrations are made using grab sampling techniques. These same techniques are used by the EERF In national and International measurement cross-check programs. The EERF participates In these programs every time they are offered, usually several times per year. The EERF also sends groups of Us canisters to operators of other radon calibration chambers for blind exposures as verification checks. As part of the EERF's participation 1n the state radon survey program, we request that the participating states expose duplicate canisters and return them to the EERF for routine processing. This Is usually done In 5 percent of the homes surveyed. The EERF also requests that the states submit blank canisters back to the EERF for analysis. These are sent In by each state at a rate of approximately 2 canisters per week. 23 ------- The sodium Iodide detectors and counting systems used for the analysis of canisters are calibrated dally using standard sources described 1n section II-D. The standard count for each detector system each day Is entered Into a computer maintained control chart (Ro65). If the dally standard count exceeds the 2 slgma variation of the average of all previous counts for that system, the system Is not used for counting until the cau'se of the excessive variation Is determined. The same type analysis Is also performed dally for a background canister on each system. In actual field use the coefficient of variation of a canister should not exceed 10 percent at a radon concentration of 4 pCI/llter or greater. This precision Is monitored using duplicate canisters (EPA86). 24 ------- IY. Survey Methods A. Shipping of Canisters Canisters are prepared for use as described In section III-A. After preparation they are Individually boxed and the Individual boxes are packed Into a shipping case, usually 150 canisters per case. These are shipped to the users through normal commercial carriers. An Individual canister In its box may be mailed to a user. Prepaid labels are used to ship the Individual boxes to the user and a prepaid label Is provided to return the canister from the user to the EERF. Each Individual box has a gummed flap for sealing the box prior to shipment. B. Deployment The charcoal canisters should be used as directed In the Interim Indoor Radon and Radon Decay Product Measurement Protocols, EPA 520/1-86-04, April 1986. The protocols specify house conditions at the time of measurement, provide Instructions on selecting the location In the house at which to make the measurement, and suggest how to interpretation of results. Copies of the Interim Indoor Radon and Radon Decay Product Measurement Protocol may be obtained by written request to either of the following addresses: U.S. Environmental Protection Agency Eastern Environmental Office of Radiation Programs (ANR-458) Radiation Facility 401 M Street, S.W. 1890 Federal Drive Washington, DC 20460 Montgomery, AL 36109 25 ------- Hurt te rim 9* Oortoel Mem Orte MTO that ft* It ho«r» before wd d*rlof the >-«v MlSoroBMl period: HndoM end enternil doors art Uft closed, tuoot for oorwl entry oaf ortt, ran or wettlatlM sjrstees that m wui* ilr. toe* M UU fiat. w« aot eetrete*. If jrour bouse has I botaMat. place ttt ctnltUr i^vtert li tin liM««t. iict»t t» |tri|i. rwt nlltr. or crtvl ifttt. If i««r kewu tow «et *« b*it«tiit. »1tM tk* cMlitor li «V rev w UM loMtt floor of tta ten*, tietpt 1o t ttUroca. kluhtn. or porck. Mttdi tt» MltcUd room. U» cmliUr ikouK Mt to lo o locttloo frtqytntlji MpoiH U Mtknblt drifU of on open door, vlnden. flrtplKt. etc. Ao unlitor «ho«U tt ti^ot»d to «1r toolo brtttht. It thovltf to p1*co« oo o Ublt or thtlf ot looit t foot obon ttt floor MM itald bt In optfl tfr. not In o clout. o>uor, cupbo*r4, ott. The unftttr should be opened ind eiyoted U the olr for t full dk/f (41 hours) «»d the* returned towdliUljr for procftslng. foil* the HOCCDUK btloi for optntng wd nttiMn( Ut ckircpsl c«Miter. Do not open the coilstor to begin U* octsvreocnt If jov annot end the to f dfys. MKIDUU 1. hone the tept fro* oround U« ceilttcr. Sin the Upe to retool the cutster ot the end of the BiiBrcotrt. t. Hoove OH lid fr» the unlsur. Piece the lottr holf of the twister, wltt the screen si* op lottft the open olr, on o Uble or shelf to the roc* chosen occordlof to the ibOM listrvctloM. L Mil to the tUrt fete end Hot oo the label on the uoliUr 114. 4. After 2 foil d»/i (48 Hours), replace the lid on the unfitcr ind rtMil It *1U the Upe. I. fill In tht step diU end tloe on tte libel. Tkls Is tirj totwrUnt. Mso. pleise fill lo V* Inforttttlon requested (To Be tacleud B/ Occvpint) OB the other side of this sheet. I. Floce the canlsUr end this sheet lo tht bo* provided. Scol the boi is shorn beloo end plice the iddreiwd. posuge-psld libel « the be*. I. Ml the boi «tthlo 1 diy of reieilloi the emitter, fc poiUoo Is roojilrod. FIGURE 6 Instruction sheet ------- C. Forms A combination data-Information form 1s shipped with each canister. The Information side of the form contains detailed Instructions for use and return of the canister. This form 1s shown In Figure 6. The other side of the form consists of blanks to be completed by the homeowner and the government agencies conducting the study. This data form Is shown In Figure 7. Accurate and complete answers In the blanks are very Important. 0. Time Restrictions The following time restrictions, In regard to exposure time and the time In transit during return of the canister, are used 1n the EERF programs. The exposure time for the canister must not be less than 24 hours (1 day) nor longer than 144 hours (6 days). The desired exposure time Is 48 hours (2 days). The time delay In returning the canister to the EERF for processing should be as short as possible to avoid excessive decay. All canisters received at the EERF are counted, regardless of the delay time. If the 3 slgma counting error 1s less than 100 percent, the results are calculated. If the 3 slgma counting error Is greater than 100 percent, the canister Is not calculated. E. Reporting Usually, all canisters received at the EERF are counted on the day they are received. The EERF reports results from canisters processed each two weeks. The report contains data for the canisters received during the 27 ------- canna » KOTO? kit Ml ttM JM lUltH Ml f Urt *tt / / TIM IMMt HM m U8 teU / / Q* M III 1. JoiUJ tip codt «t locttloa of t. T»t of bv1141»t In «ti«di Nivrioent MS Mdi: Q |1*«1« fully tarn Q HUI-f« U; building Q builntu Q Khoel Q othtr I. Poor of kwlldlfig i**r* "wcwnt nt Hdt: Q biumit Q ftrtl Hoar MC«rv4 floor or tbmt fMll/ roM Q ll»1ng roM * othtr 4. IOCB t* «Meh HiiureHnt Hi Hdt: Q btdreoB Q_f Q uiffnlihctf tatncnt Q offlci Q cl»iveo J] I. Vert tiUrler doort tnd wtadoas Httljr oota or closttf Airing Ktuirnntt Q Hottl/ optn Q Hoitlj cloud intt: ouu I.D. Code ttologk Region Co* FOR GOrUNCn OH bnliter (On unliUr 1tb*l) kit iKtlvtd (M HI BlU Counted Dttector liatar Mlgkt Ait tnUrtd tar d jrr lr«u Ce»»U thlgkt I» R Ckcctod tgr. fcrtflod tgr FIGURE 7 Data form 28 ------- previous two week period. Summary reports may be provided on request. The reports contain all the responses to questions on the data forms. If a form was not fully completed, this section will be blank on the report. Certain omissions, such as a start or stop date/time, make It Impossible to calculate a radon value. The canister, however, Is counted and the count data filed by canister serial number. If the missing data are supplied at a later date, the results will be calculated and reported on the next repqrt. If any Irregularities are noted In a canister, such as the top not taped properly, this will be noted in the comment section of the report. The responsible agency conducting the survey will be notified i by telephone if any canister result Is greater than 100 pCI/Hter. Agencies conducting surveys with the EERF canisters who have the appropriate computer equipment may access their data directly in the CERF computer. They will be given access only to their own data and will only be able to receive data from the EERF system. The EERF also can arrange to send data directly to agencies who have access to electronic mall. Interested persons should contact the EERF to arrange to get computer access or electronic mail. ------- REFERENCES A163 Altshuler, B. and Paste mack, B., Statistical Measures of the Lower Limit of Detection of a Radioactivity Counter, Health Physics, Vol. 9, pp. 293-298. Co83 Cohen, B.L. and Cohen, E.S., Theory and Practice of Radon Monitoring by Adsorption In Charcoal, Health Physics, Vol. 45, No. 50, 1983. Co86 Cohen, B.L. and Nason, R., A Diffusion Barrier Charcoal Adsorption Collector for Measuring Radon Concentration In Indoor Air, Health Physics, Vol. 50, No. 4, 1986. EPA86 Environmental Protection Agency, Interim Indoor Radon and Radon Decay Product Measurement Protocols, EPA 520/1-86-04. Ge84 George, A.C., Passive, Integrated Measurement of Indoor Air Using Activated Carbon, Health Physics, Vol. 46. No. 4. 1984. Pr85 Prkhard, H.M. and Marlon, K., A Passive Diffusion Rn-222 Sampler Based on Activated Carbon Adsorption, Health Physics, Vol. 48, No. 6, 1985. Ro65 Rosensteln, M. and Goldln, A.S., Statistical Techniques for Quality Control of Environmental Radloassay, Health Laboratory Science, Vol. 2, pp. 93-102. 30 ------- EWIROWEMM. RADIATION DMA (ERD) is published quarterly (January, April, July, CctoEerT by the 0* S. Environmental Protection Agency's Office of Radiation Programs. Requests for information concerning publication and distribution of ERD should be directed to: Charles H. Petto Technical Support Branch Eastern Environmental Radiation Facility 1890 Federal Drive Montgomery, Alabama 36109 Requests for information concerning the operation of ERAMS should be directed to: Charles R. Phillips, Chief Monitoring and Analytical Services Branch Eastern Environmental Radiation Facility 1890 Federal Drive Montgomery, Alabama 36109 or to: James H. Gunter, Chief Environmental Studies and Statistics Analysis and Support Division (ANR-461) U. S. Environmental Protection Agency Waterside Mall East 401 H Street, SW Washington, DC 20460 *** ------- |