P.1 

PICK-UP DATE: 

BOX 10 OF 10 

Step 2: FOR ASRC INTERNAL USE 

ONLY 

(PART A_ of_B ) 

i

1 

EPA DOCKET ID: 102RQ-RN 

41) 102RQ-RN-5-3 

43) lp2RQr£N-5-5 

45) 402RQ-RN-5-7> 

47) 102RQ-RN-5-9 

49) 102RQ-RN-5-11 

51) 102RQ-RN-5-13 

53) 102RQ-RN-5-15 

55) 102RQ-RN-3-4 

57) 

59) 

61) 

63) 

65) 

67) 

69) 

71) 

73) 

75) 

77) 

79) 

Step 3: FOR ASRC INTERNAL USE 

ONLY 

CD: 

OA: / 

42) 102RQ-RN-5-4 

44) 102RQ-RN-5-6 

46) 102RQ-RN-5-8 

48) 102RQ-RN-5-10 

50) 102RQ-RN-5-12 

52) 102RQ-RN-5-14 

54) 102RQ-RN-5-31 

56) 102RQ-RN-2-5-1 

58) 

60) 

62) 

64) 

66) 

68) 

70) 

72) 

74) 

76) 

78) 

80) 

Step 1: FOR ASRC INTERNAL USE ONLY X^X 

Are there more documents for this Docket in another box? \fE$y 

Till out Continuation Sheet and go to Step 2 

NO 

Internal SFUND Box Number _35 OF 283 

Initials/Date: _LDS / 3-8-2007 
P.2 

-v - \v sfid-xp- #» -s- - 7 

October 3, 1986 

MEMORANDUM 

SUBJECT: A Proposed RQ for Radium-226 in Equilibrium With Its 

Daughters 

TO: Barbara Hostage, Senior Project Officer 

Emergency Response Division 

Office of Emergency and Remedial Response 

FROM: Alan W. Messing 7*4«3T> 

Environmental Monitoring and Services, Inc. 

THRU: Greg Ricci 

Environmental Monitoring and Services, Inc. 

Radium-226 is a member of the uranium decay series and is 

found in nature associated with all of the members of this 

series. When radium-226 is isolated in pure form it will, over a 

period of years, establish equilibrium with its daughters. 

Radium-226 and its daughters are shown in Table 1 along with 

their half-lives and proposed RQs. 

After equilibrium is established, the quantity in curies of 

each of the daughters will be equal to the quantity in curies of 

the original radium-226 present . For example, if one curie of 

radium-226 is allowed to come to equilibrium, one curie of each 

of the daughters will have been formed (assuming no loss of 

gaseous radon-222), and one curie of radium-226 will remain. 

Application of the mixture rule requires that a report be 

made to the National Response Center when the sum of the curies 

of each radionuclide released (Q.) divided by the RQ for the 

This is strictly true only if the half-life of the parent is 

infinite. For radium-226 it is a good approximation. 
-1 

P.3 

TABLE 1 

RADIDM-226 AND ITS DAUGHTERS 

Radionuclide 

Radium-226 

Radon-222 

Polonium-218 

Lead-214 

Astatine-218 

Bismuth-214 

Polonium-214 

Thallium-210 

Lead-210 

Bismuth-210 

Polonium-210 

Thallium-206 

Half-Life 

1600 yr 

3.823 day 

3.05 min 

26.8 min 

2 sec 

19.7 min 

0.000164 sec 

1.3 min 

21 yr 

5.01 day 

138.4 day 

4.19 min 

Proposed RQ 

(Ci) 

1 

100 

1 

1 

1 

1 

1 

1 

0.1 

10 

0.1 

1 
P.4 

radionuclide (RQ.) is equal to or greater than one. The minimum 

release requiring a report is found when the following equality 

is satisfied: 

£ [(Qi)/(RQi)] = 1 

For a release of radium-226 in equilibrium with its 

daughters, where each radionuclide is present at a level of one 

curie, the sum of (QJ)/(RQJ) is equal to 28.11, as calculated 

below. 

(1/1)*(8) + (1/100) + (1/10) + (1/0.1)*(2) = 28.11 

Eight radionuclides in Table 1 have RQs of 1 curie, one has 

an RQ of 100 curie, one has an RQ of 10 curie, and 2 have RQs of 

0.1 curie. Clearly a release of this size would require a report 

to the National Response Center. The minimum release 

necessitating a report is 1/28.11, or a release containing 0.0356 

curie of each radionuclide. Because there are 12 radionuclides 

involved, the total activity of the release of radium-226 in 

equilibrium with its daughters necessary to satisfy the equality 

above is 12 times 0.0356 or 0.43 curie. 

Based on the mixture rule, a release of 0.43 curie of 

radium-226 in equilibrium with its daughters will require a 

report to the National Response Center.