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Radon Testing for Interiors

3-10-99

Enclosed are summary results of the radionuclide concentrations and radon emanation measurements of Cold Spring Granite Company building stone samples. For comparison, I have also included are results from rock samples (labeled Other Granites) that I had previously analyzed and some "typical" values for other common building materials that have been reported in the scientific literature. Based on these measurements several tentative conclusions can be drawn:

  • (1) The average radionuclide contents of your building material samples are similar to other average granite samples and other common earth-derived building materials such as brick and soil (Appendix, page 3, 1). Thus, the amount of gamma radiation emitted from similar masses of these building materials will be approximately the same;
  • (2) There is little sample-to-sample variation in the radon family radionuclide concentrations (see column 3, Appendix page 1);
  • (3) The radon flux is somewhat larger for the counter-top squares than for the smaller samples. This indicates that the effective diffusion length is only on the order of the thickness of the counter-top samples, i.e. several centimeters. Thus, material thicker than 5 cm (2") most likely will not emit more than the counter-top samples.
  • (4) The radon flux emanating from the Cold Spring Granite samples are less than other earth-derived building materials (see Appendix, page 1 column 6 and 7).
  • (5) Protocol #3 (direct emanation measurement by charcoal absorption) is sufficiently sensitive to accurately measure emanating power for counter-top size granite samples (see Appendix, page 1, Samples CBK3, CBK4 column 6 and 7).

A new computer model was developed to estimate the contribution of building materials to the indoor radon concentration. Two kinds of installations (70 square feet typical of a counter-top treatment and complete coverage of walls and floors) were considered in three types of houses; an average house; a large, airy house; and a small, tight house. The model results are listed in the Appendix. Page #2 summarizes the counter-top installation. As columns 3 through 4 show, the radon contribution from this kind of installation is less than 1% of the concentration found in the average US home (1.5 pCi/L). Compare those contributions with similar surface areas of other building materials (last 6 lines of page 2). Even for heavy installations of your granite materials, the radon concentrations due to these materials are much less than from similar sized areas of other building materials (see the Appendix, page 3, column 3 through 5). For example, a small, tight home whose walls and floor were covered with Charcoal Black would have an additional radon burden of 0.4 pCi/L due to the granite cover. On the other hand, walls and floors of cement would add an additional burden of 3.5 pCi/L while uncovered soil walls and floors would add a radon burden of 21 pCi/L. Thus, I believe that is reasonable to say that the materials tested pose no significant radon risk.

Daniel J. Steck, Ph.D.

 

 

 

Radionuclide Content Report

Cold Spring Granite Co.

Conducted by: Dr. DanSteck

 

 

 

Material Sample U 238 Th 232 K 40 Rn

Family Family Emanation

(Rn) (Tn) Flux Uncertainty

Bq/kg Bq/h MÇ 2

 

Charcoal Black CBK1 118 91 1273 0.41 0.41

Charcoal Black CBK2 115 83 1244 0.37 0.37

Charcoal Black CBK3 1.41 0.04

Charcoal Black CBK4 1.01 0.04

Lac Du Bonnet ldbl 121 118 1570 0.74 0.74

Lac Du Bonnet ldb2 140 112 1450 0.50 0.50

Rockville Beige rvb1 66 80 1420 0.41 0.41

Rockville Beige rvb2 46 75 1730 0.39 0.39

Rainbow mrb1 95 60 1680 0.48 0.48

Rainbow mrb2 81 136 640 0.48 0.48

Rockville rv1 67 61 1018 1.11 1.10

Rockville rv2 70 89 1247 1.54 1.54

Sierra White sw1 39 20 614 0.53 0.53

Sierra White sw2 17 17 769 0.28 0.28

Mtn. Green mg1 7 4 245 0.08 0.08

Mtn. Green mg2 5 7 301 0.06 0.06

Diamond Pink dp1 49 53 1486 0.73 0.73

Diamond Pink dp2 62 73 1622 0.09 0.98

Other Granites

St. Cloud Pink ? Conc. only 100 120 2300 0.00 0.00

Ortonville Agate Conc. only 10 15 1700 0.00 0.00

St. Cloud Red Conc. only 75 95 2600 0.00 0.00

Rockville Grey Conc. only 75 120 1600 0.00 0.00

Milbank Carnelian Conc. only 35 190 1800 0.00 0.00

Clovis,CA Acad.Blk. Conc. only 8 10 220 0.00 0.00

Alma,Que. Black Conc. only 1 6 160 0.00 0.00

Andes SA Black Conc. only 20 50 800 0.00 0.00

Lk.St.John Que. Black Conc. only 15 15 532 0.00 0.00

Reformatory Char.Blk. Conc. only 150 90 1800 0.00 0.00

 

Other material Equal area

Concrete-average Reference 30 50 500 15.00 12.00

Brick-average Reference 110 500 800 3.00 2.00

Gypsum-average Reference 12 1 80 20.00 15.00

Cement-average Reference 30 40 300 10.00 10.00

Concrete-alumshale Reference 1200 0 0 100.00 50.00

Soil –average Reference 45 52 700 60.00 50.00

Bedrock (literature)

GranGneiss-average Reference 60 85 1500 0.00 0.00

GranGneiss-low Reference 1 1 500 0.00 0.00

GranGneiss-high Reference 1835 1025 1600 0.00 0.00

 

 

 

 

 

 

 

 

Effect of Materials on Indoor Radon Report

Cold Spring Granite Company

Conduced by: Dr. Dan Steck

 

 

 

Material Sample Counter tops

 

Typical house Large, Airy Small, tight

house house

(Rn units are pCi/L)

 

Charcoal Black CBK1 0.00 0.00 0.00

Charcoal Black CBK2 0.00 0.00 0.00

Charcoal Black CBK3 0.01 0.00 0.02

Charcoal Black CBK4 0.01 0.00 0.01

Lac du Bonnet ldb1 0.00 0.00 0.01

Lac du Bonnet ldb2 0.00 0.00 0.01

Rockville Beige rvb1 0.00 0.00 0.00

Rockville Beige rvb2 0.00 0.00 0.00

Rainbow mrb1 0.00 0.00 0.01

Rainbow mrb2 0.00 0.00 0.01

Rockville rv1 0.01 0.00 0.01

Rockville rv2 0.01 0.00 0.02

Sierra White sw1 0.00 0.00 0.01

Sierra White sw2 0.00 0.00 0.00

Mtn. Green mg1 0.00 0.00 0.00

Mtn. Green mg2 0.00 0.00 0.00

Diamond Pink dp1 0.00 0.00 0.01

Diamond Pink dp2 0.01 0.00 0.01

Concrete-average Reference 0.09 0.00 0.18

Brick-average Reference 0.02 0.00 0.04

Gypsum-average Reference 0.12 0.00 0.24

Cement-average Reference 0.06 0.00 0.12

Concrete-alumshale Reference 0.62 0.02 1.19

Soil-average Reference 0.37 0.01 0.71

 

Effect of materials on indoor Radon Report

Cold Spring Granite Company

Conducted by: Dr. Dan Steck

 

 

 

Material Sample Granite Walls and Floors

Typical house Large, Airy Small, tight

house house

(Rn units are pCi/L)

 

Charcoal Black CBK1 0.01 0.00 0.14

Charcoal Black CBK2 0.01 0.00 0.13

Charcoal Black CBK3 0.03 0.01 0.49

Charcoal Black CBK4 0.02 0.01 0.35

Lac du Bonnet ldb1 0.02 0.01 0.26

Lac du Bonnet ldb2 0.01 0.00 0.17

Rockville Beige rvb1 0.01 0.00 0.14

Rockville Beige rvb2 0.01 0.00 0.14

Rainbow mrb1 0.01 0.00 0.17

Rainbow mrb2 0.01 0.00 0.17

Rockville rv1 0.02 0.01 0.39

Rockville rv2 0.03 0.01 0.54

Sierra White sw1 0.01 0.00 0.18

Sierra White sw2 0.01 0.00 0.10

Mtn. Green mg1 0.00 0.00 0.03

Mtn. Green mg2 0.00 0.00 0.02

Diamond Pink dp1 0.01 0.01 0.25

Diamond Pink dp2 0.02 0.01 0.34

Concrete-average Reference 0.31 0.13 5.23

Brick-average Reference 0.06 0.03 1.05

Gypsum-average Reference 0.41 0.18 6.97

Cement-average Reference 0.21 0.09 3.49

Concrete-alumshale Reference 2.05 0.89 34.86

Soil-average Reference 1.23 0.54 20.92

 

 

 




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