ML20210K221
| ML20210K221 | |
| Person / Time | |
|---|---|
| Issue date: | 08/03/1999 |
| From: | Zwolinski J NRC (Affiliation Not Assigned) |
| To: | Blanch P AFFILIATION NOT ASSIGNED |
| Shared Package | |
| ML20210K224 | List: |
| References | |
| RTR-NUREG-BR-0241 NUDOCS 9908060043 | |
| Download: ML20210K221 (16) | |
Text
.? o,-
August 3, 1999 i
Mr. Paul M. Blanch 135 Hyde Road West Hartford, CT 06117
Dear Mr. Blanch:
Thank you for your e-mail of June 3,1999, complimenting NRC for being responsive to many of your concerns identified over the past few years.
l Your e-mail contained four questions relating to our letter of May 19,1999, and i
NUREG/BR-0241. Our responses to your questions are enclosed, and we appreciate your participation in the decommissioning process. If you have further questions, please do not hesitate to contact me.
Sincerely, ORIG. SIGNED BY SUZANNE BLACK John k. Zwolinski, Director Division of Licensing Project Management Office of Nuclear Reactor Regulation
Enclosure:
As stated DISTRIBUTION:
Docket File (w/originalincoming)
PUBLIC (w/ incoming) ins / r erman WKane BSheron CNorsworthy (E-mail RCN)
NRR Mail Room (YT019990147 w/ incoming) (05-E7)
Making OGC ACRS/ACNW DWheeler [N/3 f <
THuffert '
/
GPowers VDricks, OPA g KBrockman, RI FCameron, OGC *No major changes to input. y To receive a copy of this document, indicate "C" in the box "See previous concurrence OFFICE PDlWQ/PM_ . O PDIV/LA C TECH ED" PDIV-D/SC NAME SNaWwif@5D CJamerson$ BCalure MMasnik grei DATE .
euu up 1 uiu g g = =
OFFICE *NMSS *RES PDIV-D/D DLPM/D /)s(L.
NAME LCamper CTrottier SRichards/f% 1 JZwolinski" '
DATE 07/08/99 07/26/99 7/ 9 0 /95" 7/ 4 /99 DOCUMENT NAME: G:' DIV-3\ GEN _YT0147.WPD OFFICIAL RECORD COPY 9908060043 990003 PDR NUREG BR-0241 C PDR
t . r, -
i l Mr. Paul M. Blanch '
l l 135 Hyde Road I l West Hartford, CT 06117 j i
Dear Mr. Bla h:
Thank you for y r e-mail of June 3,1999, complimenting NRC for being responsive to many of your concerns id tified over the past few years.
Your e-mail contain four questions relating to our letter of May 19,1999, and NUREG/BR-0241. O responses to your questions are enclosed, and we appreciate your i participation in the dec missioning process. If you have further questions, please do not hesitate to contact me.
Sincerely,
)
John A. Zwolinski, Director Division of Licensing Project Management !
Office of Nuclear Reactor Regulation )
Enclosure:
As stated DISTRIBUTION:
Docket File (w/originalincoming)
PUBLIC (w/ incoming)
PDIV-D r/f (w/ incoming)
SCollins/RZimmerman ;
WKane l BSheron l CNorsworthy (E-mail RCN)
NRR Mail Room (YT019990147 w/ incoming) ( E7)
Making OGC ACRS/ACNW DWheeler l THuffert '( l GPowers '
VDricks, OPA KBrockman, RI FCameron, OGC *No major changes to input.
To receive a copy of this document, inciscate "C" in th box "See previous concurrence OFFICE PDIV-D/PM C PDIV/LA i C TECH ED"\ PDIV D/SC NAME SNalluswami:sp CJamersor4_, BCalure \ MMasnik aus a e =- - -
OFFICE 'NMSS *RES PDIV-D/D \ DLPM/D l NAME LCamper CTrottier SRichards \ JZwolinski DATE 07/08/99 07/26/99 / /99 \ / /99 DOCUMENT NAME: G:\PDIV-3\ GEN._YT0147.WPD OFFICIAL RECORD COPY
S. . .
Mr. Paul M. Blanch i Energy Consultant 135 Hyde Road est Hartford, CT 06117 Des r. Blanch:
Thank y for your June 3,1999 e-mail complimenting NRC for being responsive to many of your cer ms identified over the past few years.
Your e-mail ntained four questions relating to our May 19,1999 letter and NUREG/BR-0241.
Our respon to your questions are enclosed and we appreciate your participation in the decommissioni process. If you have further questions, please do not hesitate to contact me.
Sincerely, l John A. Zwolinski, Director Division of Licensing Project Management Office of Nuclear Reactor Regulation
Enclosure:
Responses to y r questions DISTRIBUTION.
Docket File (w/originalincoming PUBLIC (w/ incoming) J PDIV-D r# (w/ incoming) i BSheron CNorsworthy (E-mail RCN)
NRR Mail Room (YT019990147 w/inco ing) (05-E7)
DWheeler i VDricks, OPA i KBrockman, RI l
To receive a copy of this document, indicate i ,the box: "C" = l OFFICE PDlWQ/PM , PDIV/LA TECH ED PDIV-D/SC NAME SNUlIdMsp CJamerson \ MMasnik l DATE / /99 9 i OFFICE PDIV-D/D DLPM/D
\
NAME SRichards JZwolinski DATE / 199 / /99 DOCUMENT NAME: G:\PDIV-3) GEN _YT0147.WPD OFFICIAL RECORD COPY I
4
4* **
sC 7Eoy gk Jh UNITED STATES s" j t
, NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. See6H001
/
August 3, 1999 Mr. Paul M. Blanch 135 Hyde Road West Hartford, CT 06117
Dear Mr. Blanch:
Thank you for your e-mail of June 3,1999, complimenting NRC for being responsive to many of your concerns identified over the past few years. ,
Your e-mail contained four questions relating to our letter of May 19,1999, and NUREG/BR-0241. Our responses to your questions are enclosed, and we appreciate your participation in the decommissioning process. If you have further questions, please do not hesitate to contact me. '
Sincerely,
- LtL A John A. olinski, Director ,
Division of Licensing Project Management Office of Nuclear Reactor Regulation
Enclosure:
As stated l I
r 1
- y l
l l
i RESPONSES TO QUESTIONS FROM PAUL M. BLANCH VIA E-MAIL DATED JUNE 3,1999, TO JOHN ZWOLINSKI, NRC Question 1:
Appendix C, Table 1 to the NUREG[/BR-0241] equates 10 microR/hr to 24 mr/yr. Could you please hcve a copy of this calculation sent to me. j Resoonse:
The last footnote in Table 1 states that the value of 24 mr/yr is based on an effective, unshielded occupancy of about 2,360 hours0.00417 days <br />0.1 hours <br />5.952381e-4 weeks <br />1.3698e-4 months <br /> for outside exposure, assuming an external dose rate of 10 microR per hour at 1 meter above background. It should be noted that the 2,360-hour exposure duration is an estimate of the time an individual would be exposed to direct gamma radiation from contaminated soil while spending time outdoors and indoors during a year.
The staff assumed that an individual would spend about 1,800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> outdoors exposed to unattenuated radiation from contaminated soil located on open land and would also spend 4,380 hours0.0044 days <br />0.106 hours <br />6.283069e-4 weeks <br />1.4459e-4 months <br /> indoors exposed to attenuated radiation that was located around the foundation of a house. Taking into account source geometry factors for outdoor and indoor exposures (0.74 and 0.24, respectively), the staff initially calculated an exposure duration of about 2,380 hours0.0044 days <br />0.106 hours <br />6.283069e-4 weeks <br />1.4459e-4 months <br />.
However, the staff used an annual exposure duration factor of 0.27 to take into account some of the uncertainties in the estimates ((1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> x 0.74 + 4380 hours0.0507 days <br />1.217 hours <br />0.00724 weeks <br />0.00167 months <br /> x 0.24)/8760). The annual exposure duration factor was then multiplied by the total number of hours in a year and exposure rate to arrive at an effective, unshieldedannual dose rate of about 24 millirem (8760 hours0.101 days <br />2.433 hours <br />0.0145 weeks <br />0.00333 months <br /> per year x 0.27 x 10 microR per hour).
More detailed information on the derivation of the source geometry factors and the overall dose calculation methodology used by the staff is provided in Appendix G, Volume 4, of NUREG-0782, which is entitled " Draft Environmental Impact Statement on 10 CFR Part 61,
' Licensing Requirements for Land Disposal of Radioactive Waste'." A copy of the applicable portion of this NUREG is attached for your reference.
Question 2:
If the dose rate one meter from the ground is 10 microR/hr, what is the maximum allowable exposure rate at the ground surface?
Response
The NRC regulations do not specify a maximum allowable exposure rate at the ground surface when the dose rate at 1 meter from the ground is 10 microR/hr. Currently there is no calculation available that defines the maximum allowable exposure rate at the ground surface.
Enclosure
]
r
- . ' q 2
The exposure rate will vary as the height of the detector changes because of the mass of air between a detector and a measurement point of interest, the distribution of the isotope (s) in the soil, and the type of radiation emitted. Alpha radiation is the most readily absorbed by air, followed by beta, ' hon gamma. Other factors such as soil moisture, soil composition, and air density also affect a measured exposure rate. Also, solubility and stability of the isotope or compound can change the radioactive residence time, thus causing the surface dose rate to change with time. Consequently, as the height of a detector decreases from 1 meter to surface contact, the measured exposure or dose rate will increase. Therefore, when alpha, beta, or low-energy emitters are in the soil, a maximum allowable surface exposure rate cannot be easily determined, so concentration limits are used. A discussion of the variation in terrestrial radiation can be found in National Council on Radiation Protection Report ,
Number 94, " Exposure of the Population in the United States and Canada from Natural Background Radiation," dated 1987, which is published by the National Council on Radiation Protection and Measurements.
Question 3:
It appears that the EPA [ Environmental Protection Agency) criteria of 15 mr/yr is based upon the maximum exposure to an individual whereas the NRC criteria of 25 mr/yr appears to be based on an " average dose to a member of the critical group." is there any maximum exposure limit to members of the general public at a site released for unrestricted access? Is the EPA in agreement with the assumptions used in the NRC's methodology?
Response-As stated in our letter of May 19,1999, to you, the maximum allowable TEDE (total effective dose equivalent) is 25 mrom/yr, including the dose from ground water sources of drinking water, for unrestricted use (access) of a site, and the residual radioactivity has been reduced to levels that are as low as is reasonably achievable (ALARA) (10 CFR Part 20, Subpart E, l Section 20.1402). However, the TEDE limit for individual members of the public from licensed operation is 100 mrem /yr exclusive of the dose contribution from background radiation (10 CFR 20.1301). NRC's view is that 100 mrem /yr is a safe level of exposure from all sources and ;
25 mrem /yr is a reasonable fraction of that 100 mrem /yr exposure from a single sourcs
! resulting from decommissioning.
l Our understanding of the evolution of the two different dose rates is based on the acceptability of a specific level of risk. According to the EPA, cleanup should generally achieve a level of risk i 4
within the 10d to 10 carcinogenic l risk range. The upper boundary of the risk range is not a 4
L discrete line at 1x104, although EPA generally uses 1x10 (1 in 10,000)in making risk management decisions. A specific risk estimate around 10dmay be considered acceptable if justified by site-specific conditions. On the basis of the risk estimate (by the EPA), the NRC's 4
criteria of 25 mrom/yr is equivalent to approximately 5x10 (1 in 2,000 or lower) cancer risk, whereas the 15-mrom/yr proposal by the EPA is equivalent to a cancer risk of approximately 3x10d (1 in 3,333).
1 x 3
The NRC staff is not in a position to state which assumptions EPA is in agreement with. We suggest that you contact EPA at:
U. S. Environmental Protection Agency Office of Radiation and Indoor Air (ORIA) (6601J)
. 401 M Street, SW
- Washington, DC 20460 Telephone: 202-564-9320 Qyestion 4: ,
Please explain why some licensees have elected to store sperat fuel under a Part 72 license while most of the New England plants are not being held to this requirement? Is it possible that a site could be decommissioned, released for unrestricted use without a reactor or containment and still possess a power reactor license? If this is the case, would the site be under the jurisdiction of NRR [ Office of Nuclear Reactor Regulation] or NMSS (Office of Nuclear Material Safety and Safeguards]?
Response
Our regulations do not require a licensee to inform the NRC staff as to the reacons behind its l proposal to store'its spent fuel under a Part 50 or Part 72 license. As indicated in our letter of l May 19,1999, to you, the NRC regulations in 10 CFR Part 72, Subpart K, Section 72.210, state the following: "A general license is hereby issued for the storage of spent fuel in an independent ;
spent fuel storage installation at power reactor sites to persons authorized to possess or operate nuclear power reactors under [10 CFR) part 50 of this chapter." Subpart K gave all utilities with a 10 CFR Part 50 license a general license thJ allowed them to store their spent fuel in a dry cask storage system (DCSS) that has received a certificate of compliance from the NRC. As stated in NUREG-1571 ("Information Handbook on independent Spent Fuel Storage Installations," December 1996), the basis of the new Subpart K was that existing reactor sites already met 10 CFR Part 72 licensing criteria (i.e., physical protection, environmental impact statements, emergency planning) under their 10 CFR Part 50 reactor license. Therefore the Commission believes that storage of spent fuel under a Part 50 license using a DCSS, which has received a certificate of compliance from the NRC, provides adequate protection of public health and safety and protection of the environment.
As you are aware, a licensee can also choose to license the independent spent fus! storage installation (ISFS1) under a site-specific Part 72 license that does not require maintaining the Part 50 license. Since we do not require a licensee to justify its decision to choose the general or site-specific licensing option for the ISFSI, the staff is reluctant to speculate on why licensees in .New England are choosing to store their spent fuel under a general licensa.
Your second question asks "Can the licensee build and operate an ISFSI under the provisions
'of a Part 50 general license, then clean the site and release the entire site for unrestricted use except for the ISFSI, could the ISFSI still remain licensed under Part 50?" The answer is yes
- because the Past 50 license would not be terminated for that portion of the site occupied by the ISFSI.
4 in response to your last question related to which NRC organization retains regulatory oversight, a memorandum of understandirg between NMSS and NRR assigns regulatory project management and oversight of a reactor undergoing decommissioning to NMSS after the spent fuel is permanently transferred to day storage irrespective of the type of ISFSI license.
Attachment:
Pages G-60 through G-65 of NUREG-0782, v. 4
- - c I
t NUREG-0782 Vol. 4
- . - - - - - - - - - - - - - - - , - - - - - - - - - + - - - - - - - - - - - - - - * ^ * - - - - ~ ~
Draft '
Environmental Impact Statement on 10 CFR Part 61 " Licensing Requirements for Land Disposal of Radioactive Waste" Appendices G-Q
~~ ~ ~~
U.S. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards September 1981
,.*~.,
- f. -
\.\. . . ./:
ATTACHMENT
c l
G-60 i
In this EIS, the exposure duration is assumed to be 500 working hours. This I
is equivalent to a construction period of 3 months, which is believed to be reasonably conservative for typical housing construction. It is believed to be very conservative for activit es involving use of heavy construction equip-ment. This gives a value of .0 for f for the direct gamma scenario. For the air pathways, this number multiplied by a soil-to-air transfer factor given by the formula:
T,, = [Tsa 3 ox (10/v) x (s/30) x (50/PE)2 (c.11) l where [T 8 is equal to 2.53 x 10 10 (Ref. 1), v is the average wind speed at thesitein]m/sec,sisthesiltcontentofthesitesoilsinpercent,andPE is the precipitation-evaporation indax of the site vicinity indicative of the antecedent moisture conditions. For the reference disposal facility, these values were determined to be v = 3.61 m/sec, s = 50%, and PE = 91, yielding a value of 3.53 x 10 10 for T factorof0.057,thisyieldga(alsoseeAppendixJ). For an exposure duration air uptake component of the construction a site selectionscenario. factor of 2.01 x 10 12 for the Disposal With Barriers Against Intrusion The barrier factors f and f are affected if the waste is disposed using intruder barriers andfor if waste segregation is implemented at the disposal facility.
For the air uptake pathways, (a) for layered disposal, the factor f
d is multiplied by a factor of 0.1 to indicate the likelihood of contact of ~
tne layered wastes by the intruder; and (b) for iist waste facility disposal, f d is multiplied by a factor of 0.01.
For the direct gamma exposure pathway, (a) for layered disposal,d f is multiplied by a factor of 1/1200 which denotes attenuation of the radiation tnrough a layer equivalent to 1 meter of Loih and (b) for hot waste facility disposal, f dis multiplied by a factor of 1/12002 (Ref. 2) which indicates attenuation or the radiation through a layer equivalent to 2 meters of soil.
The site selection factor, f is modified only if the waste form is stable andhasbeendisposedinasIg,regatedmanner. Ir. this case, which is termed d the intruder-discovery scenario, the exposure duration factor is reduced from
, 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> for all the uptake pathways (Ref.1).
3.4.2 Intruder-Agriculture Scenario The intruder-agriculture scenario assumes that an intruder inadvertently lives on and consumes food grown on the disposal facility.
Farming is a surface activity and generally does not involve disturbing the soil for more than a few feet. As long as a cap of one or two meters is '
maintained over the waste, then it is very unlikely that agricultural activities would ever contact the waste. To implement the scenario at the end of the active institutional control period, however, a portion of the soil excavated during the intruder-construction activity (232 m a of waste and 680 m_,_nf_sover 3
- ' c G-61 material) is assumed to be distributed around the house. After building the foundations.of the house, about 312 m 8 of this soil would be backfi.11eo outside and around the cellar walls, leaving a volume of about 600 m8 of soil (of which about 150 m8 is the original waste / soil mixture) involved in the agriculture scenario. The precise areal extent to which this soil is distributed is somewhat speculative. It is likely, however, that the soil will remain localized; moving even a few cubic yards of soil more than 10 meters usually requires a significant effort. It is assumed in this report that this areal 2
extent is likely to be somewhere between 1000 m2 and 2000 m . That is, the waste / soil mixture is assumed to lie within a radius of about 25 meters from the center of the house. The intruder is then assumed to live in this distributed waste / soil mixture and is also assumed to consume vegetables from a small garden located in the waste / soil mixture.
A possible alternative to this scenario is that the waste cover is stripped away by the intruder, and that the intruder lives on and grows and consumes food grown directly in the waste. This does not appear to be as reasonable as the above scenario. At current commercial rates, it costs about $1.07 to move one cubic yard of dirt from one place to an adjacent place with heavy equipment (Ref. 28). This implies that to clear 2 meters of cover from 2 acres, the intruder would have to either invest a sum of about $22,500 or perform labor equivalent to this sum. This is not a reasonable assumption since no reasonable person is likely to strip and clear away surf ace soil with the hope of finding better soil underneath to grow food. A noncommercial enterprise is therefore assumed for the intruder-agriculture scenario. It appears to be unreasonable I
to expect that a commercial operator, who would require a substantial investment '
for a commercial agricultural operation and therefore a clear title to the land, can be an inadvertent intruder.
The inadvertent intruder is assumed to live in the house built on the site, work at a regular job during the day, and spend some of his extra time working in a garden growing vegetables for his own use. His time during a year is assumed to be allocated between various activities as follows: ;
Activity Hours / Year At Home 4380 At Work 2000 Traveling To and From Work 250 Vacation 330 Gardening 100 Outdoors 1700 Total: 8760
r 1
G-62 In the intruder principally by five agriculture pathways:scenario, the inadvertent intruder could be exposed due to tilling activities as well as natural suspension, (2) direct gam exposure from standing in the contaminated cloud, (3) consumption of food tion of food grown in the contaminated soil, and (5) direc from the disposed waste volume.
For calculational convenience, the first three uptake pathways have been grouped together and denoted as the air pathway. uptake groups: The potential exposures from these pathways are calculated in three These are then Wied to arrive at the total potential exposures scenario.
In this EIS, the potential exposures from the intruder-agriculture scenario are calculated using the following equation:
H=
E n (f,f Idws # ) air C, PDCF-3 n+ E (f,fdwsI I ) food C, N H +
E n
(f,f I dws I )DG C, PDCF-5 (G-12) where H is the annual dose in mrem per year during the 50th year of exposure, PDCF-3, PDCF-4, and PDCF-5 are the radionuclide-specific dose conversion factors presented in Section 2.4, and C the waste.
Impacts are summed over all*the is the radionuclide radionuclides (n).concentration in the barrier factors are presented below. The values of The time delay factor, f , for this scenario is identical with the construction scenario,andisgivenbyequation(G-4). The site design and operation factor f a is also determined in the same manner as the construction scenario .
In additTon, the dilution resulting 8from mixing the excavated waste (232 8 m) with the excavated cover soil (680 m ), which is a factor of about 0.25, is also included in the design and operation factor. ~
The waste form and package factors for the air uptake and direct gamma exposure pathways composing this scenario are identical to those for the air uptake and direct gamma pathways composing the intruder-construction scenario.
For the food (soil) uptake pathway, two options are available to calculate f depending upon whether credit is given for the waste form to reduce leaching",
of radionuclides from disposed waste and subsequent uptake by plant roots.
These options are included to help investigate the potential for improved waste forms to reduce potential intruder impacts.
option, the following formula is utilized to calculate fFor the waste form credit uptake pathway (also see equation G-16):
- for the food (soil) f, = M,x t c x u I6,D ,IS) x 10 (P1O
- c
\
G-63 )
However, in the waste form no-credit option, the factor Mult(16,I7,IS) is set equal to 1.0.
In equation G-13, M is the radionuclide-specific leach fraction of unsolidified wasteforms(seeSe8 tion 3.5). The contact time fraction t is the fraction of time in one year that the waste is in contact with irrig8 tion or rainwater, while 19 is the accessibility index (see Section 3.2.6). Mult(I6,77,IS) is ,
(
the reduction due to solidification and the presence or absence of chelating l chemicals (see Section 3.2.4) and is a function of leachability index (I6), i the chemical content index (17), and whether the waste streams containing chelating or chemical agents have been segregated from other waste streams (IS).
It appears to be reasonable to assume that only the fraction of radionuclides transferred from the waste to the interstitial water will be accessible to the roots. Inclusion of contact time in the above equation is consistent with this approach. The contact time fraction is conservatively assumed to equal unity in this EIS; however, this fraction may actually be a very low value in view of the soils likely to be found at most disposal locations. These locations are likely to be at topographic highs whereas the most attractive agricultural soils are found in or adjacent to flood plains.
The site selection factor f for the air uptake pathway is similar to the intruder-construction air uhtake pathway. However, the soil-to-air transfer factor must be averaged to account for natural resuspension of the soils during part of a year. This estimate is calculated by assuming that (1) the construction scenario T va (see Section 3.3.1) is applicable duringgardening(100h88rs)lueof3.53x1010
- (2) during the time spent outdoors (1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br />),
typical natural outdoor ambient air particulate concentrations of 100 ug/m3 are assumed to prevail (Ref. 27); and (3) during the time spent indoors (4380 hours0.0507 days <br />1.217 hours <br />0.00724 weeks <br />0.00167 months <br />), typical ambient indoor concentrations of 50 ug/m 8 have been assumed (Ref. 27). Utilizing a mass loading of 565 ug/m 8 for the time spent while gardening (Ref. 1), and averaging these values results in a site-selection factor value of 3.18 x 10 11 This may be compared with the vilue of f 5
(2.01 x 10 11) calculated for the intruder-construction scenario.
Fct the food (soil) uptake pathway, f is taken to be the fraction of food grown onsite that is consumed by the individual. This value is assumed to be
- 0. 5. For the direct gamma exposure pathway, f, is equal to the exposure duration fraction multiplied by a correction f8ctor to arenont for the limited T eal extent of the cirect gamma source that the intruder is exposed to.
'Moreover, the fracticn or tne time the intruder spends in relation to tnr s:urce must be considered.
During a year, the intruder is assumed to spend 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> outdoors exposed to unattenuated radiation (100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> tilling and 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> around the house).
During the 4380 hours0.0507 days <br />1.217 hours <br />0.00724 weeks <br />0.00167 months <br /> he spends indoors, he is exposed to attenuated radiation.
The correction factor due to the areal extent of the source may be estimated utilizing Figure G.S. This figure shows that the intruder may be assumed to be exposed to a full disk source while outside, and an annular source while inside the house. While he is inside the house, the center of the disk
r.-
i :' z-l G-64 i
- I l
l lNDOORS OUTDOORS i
i e EXPOSURE PolNT
/ d h .
d r2 '2 P 1 rg 0 y
a <
l SIDE VIEW i
/,
//
<i, ,
,/l/,/, '
/. '//- I r . .ry _
'//, ' -
i
,! ;! . j
/
l WASTE HOUSE TOP VIEW l
Figure G.5 Direct Gamma Exposure Geometry
- W^
r1 j I:* c l'
I G-65 represents the shielding provided by the foundation slab. The contribution to the direct gamma exposure from this center portion may be neglected in comparison with the exposure from the outside of the house. If the foundation slab is a one-foot thick concrete layer, the radiation would be attenuated to about 0.03 of its unshielded value for Cs-137 gamma rays (Ref. 1). The correction factor for the areal extent of the annular source may be represented by the following equation- -
I c = [Es(prt) - E (pr z )] / Eg(pr g) (G-14) where c is the dimensionless correction factor, E 3(x) is the first order ,
exponential integral, p is the linear attenuation coefficient of air in units of m 1 (it is taken to be 0.0097 m 1) and the r's are the distances indicated in Figure G.5 in meters (Ref. 1).
For a full disk source (for the time spent outdoors), the radius r in equation G-14 is replaced by r . In order to evaluate the correction factor, the distances must be assumed.g The following table gives the value of the exponential integral for some representative distances:
Distance pr E i (pr) 1m 0.0097 4.068 8m 0.0776 2.055 20 m 0.1940 1.335 25 m 0.2425 1.068 For r and rg, it is reasonable to assume 1 m and 8 m, respectively; 1 m repreEentstheheightoftheexposedperson,and8mrepresentstheapproximate radius of's 200 mz house floor. The value assigned to r2, however, depends on the areal extent to which the waste / soil mixture (600 m 8 ) has been spread. l This mixture will likely be spread unevenly within about a half acre around the house excavation, and the areal extent is likely to be between 1000 m 2 and 2000 m2 . A radius of 20 m represents an area of about 1050 m2 over which the waste is spread, while a radius of 25 m represents an area of about 1750 m2 ,
A radius of 25 m is utilized in this EIS.
These assumptions yield a correction factor for the time spent outdoors of about 0.74, aoJ a correction factor for the time spent indoors of about 0.24.
Utilizing values of 1800 h outdoors and 4380 hours0.0507 days <br />1.217 hours <br />0.00724 weeks <br />0.00167 months <br /> indoors yields a site selection factor of about 0.2 which is the value utilized in this EIS.
L 3.5 Ground-Water Scenarios These scenarios calculate the impacts resulting from ground-water migration of radionuclides from the disposed wastes to four potential biota access locations downstream in the direction of the ground-water flow: (1) a well located at
[
the boundary of the disposal area; (2) a well located at the site boundary; l
t
5 h/
(b /b ORIGINAL DUE DT: 07/Xf[99 TICKET NO: 019990147 FROM: DOC DT: 06/03/99 Paul Blanch NRR RCVD DATE: 06/04/99 TO:
John Zwolinski FOR SIGNATURE OF : ** YEL **
DESC: ROUTING:
YOUR LETTER OF MAY 12, 1999 AND NUREG/BR 0241 Collins /Zimmermn Kane Sheron NRR Mailroom ASSIGNED TO: CONTACT:
DLPM Zwolinski h 6 SPECIAL INSTRUCTIONS OR REMARKS:
()V h G Qf X j t
i l
l l