EPA Air Docket A-98-49, Item II-B1-32; August 2014
Environmental Protection Agency's Confirmatory Dose Calculations of the
Department of Energy's Use of CAP88-PC for the February 2014 Radiological
Emission Release at the Waste Isolation Pilot Plant
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EPA Air Docket A-98-49, Item II-B1-32; August 2014
Environmental Protection Agency's Confirmatory Dose Calculations of the
Department of Energy's Use of CAP88-PC for the February 2014 Radiological
Emission Release at the Waste Isolation Pilot Plant
Table of Contents
1.0 Executive Summary		3
2.0 Accident Description		3
3.0 Station B Filter Analysis		3
Table 1: DOE's Station B Filter Data Collected
Between February 14 and February 21, 2014		4
4.0 Regul atory Requi rem ents		4
5.0 DOE Dose Calculations		5
6.0 EPA Confirmatory Calculations		5
Table 2: DOE and EPA Highest CAP88-PC EDE Results		6
References		7
Attachment I: Location of Nearby Residences and Communities
in the Vicinity of WIPP		8
Attachment II: DOE's CAP88-PC Inputs		9
Table II.l: Source Term Used in CAP88-PC		9
Table II.2: WIPP Fence Line Where CAP88-PC EDEs Are Calculated		9
Table II.3: CAP88-PC Meteorological Inputs		10
Attachment III: EPA's CAP88-PC Results		11
Table III. 1: CAP88-PC Effective Dose Equivalents Derived by EPA,
Version 3 and 4		11
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EPA Air Docket A-98-49, Item II-B1-32; August 2014
1.0 Executive Summary
On February 14, 2014, an event took place in the underground of the Department of Energy (DOE)
Waste Isolation Pilot Plant (WIPP) that led to the release of a small but measurable amount of
radioactive material to the atmosphere. DOE is responsible for assuring that any radiological emissions
from the WIPP do not exceed an effective dose equivalent (EDE) of 10 millirem (mrem)/year to any
member of the public. CAP88-PC is the U.S. Environmental Protection Agency's (EPA) computer
software system for calculating dose and risk from annual average releases of radionuclides to the air
and can be used by DOE to demonstrate compliance with EPA regulations.
DOE performed dose calculations using CAP88-PC Version 3 to assess the location of the highest dose
at and outside of the WIPP fence line. DOE's results indicated the highest EDE was 0.67 mrem/year at
the fence line location 347 meters (-0.2 miles) northwest of the WIPP Station B exhaust shaft. Using
radionuclide release data collected and provided by DOE, EPA staff were able to recreate DOE's results
for this location. Additionally, EPA performed CAP88-PC calculations with Version 3 to verify the
highest EDE in a populated area outside of the WIPP Land Withdrawal Boundary (LWB) was below the
regulatory limits. These calculations found the highest EDE for a populated area outside of the WIPP
LWB to be 0.005 mrem/year at the Smith Ranch, which is located 7186 meters (-4.5 miles) northwest of
the exhaust shaft.
EPA also performed dose calculations with CAP88-PC Version 4, which uses updated age-specific
breathing rates and updated dose conversion and utilization factors. The effective dose equivalents were
lower using CAP88-PC Version 4. Thus, both the DOE and EPA dose calculations resulted in a
maximum effective dose equivalent below 1 mrem/year, which is less than the regulatory limit of 10
mrem/year.
2.0 Accident Description
On February 14, 2014, at 2314 hours Mountain Standard Time (MST), an underground continuous air
monitor at the Waste Isolation Pilot Plant measured elevated levels of alpha-beta airborne activity. This
caused the underground mine ventilation system to switch to filtration mode. In filtration mode the
aboveground bypass dampers are closed and mine exhaust air is rerouted through the high efficiency
particle air (HEPA) filtration system, then exhausted at effluent monitoring Station B. Due to leakage
around the dampers, a small amount of mine exhaust bypassed the HEPA filters and was exhausted
without being filtered. The aboveground ambient fixed air sampler (FAS) on the WIPP site detected
airborne alpha and beta activity levels that were above background levels downstream from the HEPA
filter exhaust measured at Station B. The bulk of the radioactive releases to the atmosphere lasted
approximately 90 hours. DOE has since sealed the air exhaust duct dampers that allowed a small amount
of radioactive particles to escape.
3.0 Station B Filter Analysis
During the February 14 radiological event, data was collected from the FAS located downstream from
the Station B exhaust duct. The Station B FAS filter records the global activity as total alpha/beta
disintegrations per minute (dpm). Filters were removed and replaced with new filters on an eight hour
cycle immediately after the release. The FAS filter that collected the initial high dpm values during the
February 14 release was removed from the Station B FAS on February 15 at 0820 hours MST. This
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EPA Air Docket A-98-49, Item II-B1-32; August 2014
filter was sent to WIPP Laboratories for analysis to determine the individual radiological and isotopic
components that contributed to the global activity. The isotopic components of subsequent filters
collected at Station B were estimated based on laboratory analysis conducted on the first post-incident
filter. Table 1 lists DOE's calculated radiological components and activities from the Station B filters
collected between February 14 and February 21. DOE provided this data to EPA in an EXCEL file.1
Table 1: DOE's Station B Filter Data Collected Between February 14 and February 21, 2014
Station B Filter Isotopic Activity
Total Curies (Ci) over the 7.334 day (10566 minutes) peak release period.
Radionuclide
Activity (Ci)
Am-241
1.69 E-03
Pu-238
4.82 E-06
Pu 239/240
9.35 E-05
Sr-90
5.38 E-08
Cs-137
2.42 E-07
U-233
3.53 E-08
U-238
5.14 E-09
4.0 Regulatory Requirements
Pertinent to the WIPP and as a requirement in EPA's Code of Federal Regulations (CFR) Title 40 Part
191, Subpart A, "Environmental Standards for Management and Storage," DOE is to assure annual
doses to the public from a nuclear repository are limited. More specifically, in 191.03(b), the DOE is to
...provide a reasonable assurance that the combined annual dose equivalent to any member of
the public in the general environment resulting from discharges of radioactive material and
direct radiation from such management and storage shall not exceed 25 millirems to the whole
body and 75 millirems to any critical organ.
Furthermore, the EPA has authority to regulate air emissions (through the Clean Air Act) to the
environment from DOE facilities, per 40 CFR Part 61, Subpart H, "National Emission Standards for
Emissions of Radionuclides Other Than Radon from Department of Energy Facilities". However, in
Section 90, "Designation of Facilities", it states that DOE disposal facilities are explicitly excluded. In
order to implement and facilitate the Part 191 Subpart A requirements, the DOE and EPA agreed—via a
1995 Memorandum of Understanding2—that the WIPP will comply with Part 61, Subpart H until
repository closure. The specifics in 40 CFR Part 61 satisfy the air emission component for periodic
confirmatory measurements. Title 40 CFR 61.92 gives DOE responsibility for assuring that radiological
emissions from the facility do not exceed an effective dose of 10 mrem per year to any member of the
1	Vincent, Oba of the Department of Energy, email message to TomPeake, U.S. EPA, March 12, 2014. Subject: CAP88
Special Input/Output files.
2	Department of Energy and Environmental Protection Agency. "Memorandum of Understanding Between the U.S. EPA and
the U.S. DOE Concerning the Clean Air Act Emission Standards for Radionuclides 40 CFR § 61, Including Subparts H, I, Q
& T." Signed by Mary D. Nichols, EPA Assistant Administrator for Air and Radiation: September 29, 1994. Signed by Tara
O'Toole, DOE Assistant Secretary for Environment, Safety, and Health, April 5, 1995. See
http://www.epa.gov/radiation/docs/neshaps/epa doe caa mou.pctf.
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EPA Air Docket A-98-49, Item II-B1-32; August 2014
public.3 Title 40 CFR 61.93 requires periodic sampling at release points which could cause an effective
dose equivalent (EDE) in excess of 1% of the 10 mrem/year limit.
CAP88-PC calculates EDE and risk from annual average releases of radionuclides to the air. The
software is developed and maintained by EPA and is one of several that can be used to demonstrate
compliance with EPA regulations at 40 CFR Part 61, Subpart H.
5.0 DOE Dose Calculations
DOE performed dose calculations using CAP88-PC Version 3 to assess the location of the highest EDE
outside of the WIPP's fence line. In a March 12, 2014 email transmission4, DOE sent EPA the
calculated high EDE, at a specific location along the fence line and the calculated radionuclide
concentrations in the environment within an 80 km (-50 mile) radius of the air exhaust shaft. DOE's
radionuclide inputs (i.e., the source term) are provided in Table 1. It is presumed in the model that these
are the only radionuclides released to the atmosphere in the WIPP vicinity during the entire year that
would cause an exposure to a target individual.
DOE performed dose calculations along the perimeter of the WIPP fence line because it is a location
where a member of the public can approach the WIPP site unfettered and, hypothetically, would result in
maximum exposure if residing there. The fence line outlines the perimeter of the WIPP facility buildings
and is within the LWB. DOE's CAP88-PC results indicated that the highest concentration of
radionuclides was at the northwest fence line location 347 meters (-0.2 miles) from the WIPP Station B
exhaust shaft, with the EDE at this location calculated at 0.67 mrem/year.
The EDE at the fence line was well below the 10 mrem/year regulatory dose limit specified in 40 CFR
61.92. DOE's results indicated that radionuclide concentrations outside of the Land Withdrawal
Boundary were significantly lower than those at the fence line. EPA presumed the calculated EDE
further from the fence line would be lower but performed additional confirmatory calculations using
CAP88-PC Versions 3 and 4 to verify this assumption.
See Attachment II for a list of DOE input files.
See Attachment III for a table of EPA's CAP88-PC results.
6.0 EPA Confirmatory Calculations
CAP88-PC calculations are performed on a radial computational grid divided in concentric sectors with
the source point at the center. The sectors are divided in compass directional subsectors. The EDE for a
location of interest is determined by the directional sector it lies in. Calculated EDE are limited to an 80
km (50 mile) radius. (See Attachment I)
With Version 3 of CAP88-PC, EPA was able to replicate DOE's EDE of 0.67 mrem/year along the
northwest fence line. The Agency's confirmatory CAP88-PC Version 3 calculations used the same
radial grid and source term as DOE to assure DOE's results were reproducible. EPA also replicated the
3	As defined in 40 CFR 191.02, a member of the public is any individual except during the time when that individual is a
worker engaged in any activity, operation, or process that is covered by the Atomic Energy Act of1954, as amended.
4	Vincent, Oba of the Department of Energy, email message to TomPeake, U.S. EPA, March 12, 2014. Subject: CAP88
Special Input/Output files.
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EPA Air Docket A-98-49, Item II-B1-32; August 2014
same radionuclide concentrations within the 80 km radius of the exhaust shaft. (Note, these
concentrations are used to generate EDEs within each radial sector and are additional output of CAP88-
PC.) The EPA wanted to assure the EDEs in populated areas within an 80 km radius of the WIPP's
exhaust shaft were below the 10 mrem/year regulatory limit. EPA's confirmatory calculations produced
the highest EDE in a populated area outside of the LWB of 0.005 mrem/year at Smith Ranch. Smith
Ranch is 7186 meters (-4.5 miles) northwest of the exhaust shaft.
EPA also performed dose calculations with CAP88-PC Version 45, which includes updated age-specific
inhalation and ingestion rates, incorporates more refined radionuclide build-up and removal rates and
includes more isotopes due to ingrowth and decay. For these calculations, EPA identified the maximally
exposed individual as an adult, thus allowing for a comparison to the "effective target individual" in
Version 3. The intention in performing calculations with CAP88-PC Version 4 was to compare results
with those derived from Version 3 and assure the calculated EDE estimates did not exceed the 10
mrem/year regulatory limit.
Results from CAP88-PC Version 4 were lower than the results from Version 3. The highest calculated
EDE, 0.42 mrem/year, was at the fence line 347 meters northwest of the WIPP exhaust shaft, which was
the same location calculated using Version 3. The highest EDE for the nearest population center outside
of the WIPP Land Withdrawal Boundary was at the Smith Ranch, as was produced with Version 3, with
an EDE of less than 0.005 mrem/year. Table 2 lists the DOE and EPA EDE results at the WIPP fence
line and Smith Ranch.
Table 2: DOE and EPA Highest CAP88-PC EDE Results
Highest Results From DOE and EPA Calculations Using CAP88-PC Versions 3 and 4

Effective Dose Equivalent (mrem/year)

Location
DOE Results
EPA Results
EPA Results
CAP88-PC
CAP88-PC
CAP88-PC

Version 3
Version 3
Version 4
Fence Line -



347-m NW of Exhaust
0.678
0.678
0.42
Shaft



Smith Ranch
Not Given to EPA
0.005
0.003
For both Version 3 and 4 simulations, the main contributors to dose were americium-241, plutonium-
238 and plutonium-239. Consistently, both DOE and EPA dose calculations resulted in a maximum
EDE below 1 mrem/year, well below the regulatory limit of 10 mrem/year. The effective dose
equivalent calculated by EPA using both CAP88-PC Version 3 and 4 at all the population centers can be
found in Attachment III.
5 CAP88-PC Version 4 is still undergoing testing and is not yet approved by EPA for regulatory compliance demonstrations.
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EPA Air Docket A-98-49, Item II-B1-32; August 2014
References
Department of Energy and Environmental Protection Agency. "Memorandum of Understanding
Between the U.S. EPA and the U.S. DOE Concerning the Clean Air Act Emission Standards for
Radionuclides 40 CFR § 61, Including Subparts H, I, Q & T." Signed by Mary D. Nichols, EPA
Assistant Administrator for Air and Radiation: September 29, 1994. Signed by Tara O'Toole, DOE
Assistant Secretary for Environment, Safety, and Health, April 5, 1995. See
http://www.epa.gov/radiation/docs/neshaps/epa doe caa mou.pdf.
Environmental Protection Agency (EPA). "40 CFR Part 191, Subpart A, Environmental Standards for
Management and Storage." 58 Federal Register 66398 (20 December 1993).
Environmental Protection Agency (EPA). "40 CFR Part 194, Criteria for the Certification and
Recertification of the Waste Isolation Pilot Plant's Compliance with the 40 CFR Part 191 Disposal
Regulations: Final Rule." 61 Federal Register 5224 (9 February 1996).
Environmental Protection Agency (EPA). "40 CFR Part 61, Subpart H, National Emission Standards for
Emissions of Radionuclides Other Than Radon from Department of Energy Facilities." 67 Federal
Register 57166 (9 September 2002).
Vincent, Oba of the Department of Energy, email message to Tom Peake, U.S. EPA, March 12, 2014.
Subject: CAP88 Special Input/Output files.
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EPA Air Docket A-98-49, Item II-B1-32; August 2014
Attachment I: Location of Nearby Residences and Communities in the Vicinity of WIPP
Depiction of CAP88-PC computational radial grid centered at the WIPP exhaust shaft
and overlain by nearby populated areas.
location or NearOv Pes (deuces *xJ Coromunfcles * me V«clnKy of WIPP

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EPA Air Docket A-98-49, Item II-B1-32; August 2014
Attachment II: DOE's CAP88-PC Inputs
The source term used in EPA's CAP-88 PC Version 4 calculations was the same as in DOE's Version 3
runs. DOE transmitted this data to EPA in an EXCEL file.1 Version 4 of CAP88-PC calculates more
radionuclide ingrowth and decay activity, which includes the radionuclide Barium (Ba). Therefore, a
non-zero value for the isotope Ba-137 was needed in the input file that was not required for the Version
3 runs.
Table II.l: Source Term Used in CAP88-PC
Station B Filter Isotopic Activity
Description
Total Curies (Ci) per the 7.337 day (10566 minutes) peak release period.
Radionuclide
Chemical Form
Particle
Type
Size
Activity (Ci)
Am-241
P
M
1
1.69 E-03
Pu-238-P
P
M
1
4.82 E-06
Pu 239/240-P
P
M
1
9.35 E-05
Sr-90-P
P
M
1
5.38 E-08
Cs-137-P
P
F
1
2.42 E-07
U-233-P
P
M
1
3.53 E-08
U-238-P
P
M
1
5.14 E-09
Ba-137
N/A
0
N/A
1.0 E-25
The letter 'P' denotes the nuclide's chemical form is a partic
e.
The choices for particle type, as specified in EPA's Federal Guidance Report 13,
"Cancer Risk Coefficients for Environmental Exposure to Radionuclides," are fast (F),
medium (M) or slow (S).



Table II.2: WIPP Fence Line Where CAP88-PC EDEs Are Calculated
Distance From Exhaust Shaft to Fence Line Boundary of the WIPP Exclusive Use
Area
Direction From
Exhaust Shaft
Distance (m)
Distance (km)
Distance (mi)
NW, S
347
0.347
0.22
SSE
376
0.376
0.23
N, SE
490
0.490
0.30
NNW, NNE
530
0.530
0.33
W, SSW, E
592
0.592
0.37
WNW, WSW, ESE, E
646
0.646
0.40
NW, NE
691
0.691
0.43
SW
778
0.778
0.48
1 Vincent, Oba of the Department of Energy, email message to TomPeake, U.S. EPA, March 12, 2014. Subject: CAP88
Special Input/Output files.
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EPA Air Docket A-98-49, Item II-B1-32; August 2014
The meteorological input file was the data collected at the DOE meteorological tower during the week
spanning the event. The tower is located approximately 600 m (1,970 ft) northeast of the Station B. This
station measures precipitation as well as wind speed, wind direction, relative humidity and temperature
at 2, 10, and 50 m above ground (6.5, 33, and 165 ft).
Table II.3: CAP88-PC Meteorological Inputs
Meteorological Parameter
Description and Notes
Temperature
Temperature value was rounded up to 15.4 degrees C in
DOE's summary file
Average Temperature
(Celsius)
15.39

Total precipitation during the event that spanned 7.34 days.
This value was input into CAP88 Version 3. Version 4
Precipitation
requires a non-zero value for precipitation. EPA input a very
low value precipitation.

Precipitation Unit
Value

mm
0.0 (Version 3)

0.01 (Version 4)

Absolute Humidity
Humidity
Unit
Value

g/meter3
8
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EPA Air Docket A-98-49, Item II-B1-32; August 2014
Attachment III: EPA's CAP88-PC Results
Table III. 1: CAP88-PC Effective Dose Equivalents Derived by EPA, Version 3 and 4.
Population Centers and Populated Areas Within 80 km of the WIPP Exhaust
Population
Center
Pop #
Compass
Direction
from Shaft
Distance3
CAP88 Results 1
(mrem/year)
m
km
Version 3
Version 4
Mills (James) Ranch
5
ssw
5240
5.24
< 3.4E-03
< 2.1E-03
Smith [Crawford]
Ranch
1
WNW
7186
7.19
< 4.9E-03
< 3.10E-03
Mobley Ranch
0
SW
9580
9.58
< 2.3E-03
< 8.2E-04
Pue Ranch
5
WNW
15495
15.5
< 2.0E-03
< 1.20E-03
Malaga CDP
147
WSW
32187
32.19
-2.2E-04
< 1.4E-04
Loving CCD
2179
WSW
32187
32.19
-2.2E-04
-1.4E-4
Loco @ 20 mi NW
150
NW
32187
32.19
< 1.2E-03
< 7.5.0E-04
Livingston Wheeler
609
W
45062
45.06
< 5.8E-05
< 3.6E-05
Carlsbad city
26138
W
48280
48.28
< 5.8E-05
< 3.6E-05
Loco Hills
149
NNW
48280
48.28
-4.30E-04
< 2.7E-04
Loving Co
(Red Bluff &Orla)
74
SSE
51499
51.5
< 9.0E-05
< 3.4E-04
Happy Valley
(CDP)
519
W
56327
56.33
< 5.80E-05
< 2.2E-05
White City (DP)
7
WSW
61155
61.16
< 9.20E-04
< 5.8E-05
Monument CDP
206
NE
64374
64.37
< 1.40E-04
< 9.0E-05
Eunice CCD
1610
E
64374
64.37
< 8.70E-05
< 5.5E-05
Kermit City 2
5708
SE
67593
67.59
< 6.20E-05
< 3.9E-05
JAL CCD 2
3220
ESE
72421
72.42
< 1.10E-04
< 7.0E-05
Atoka CDP 2
1077
NW
72421
72.42
< 5.10E-04
< 3.2E-04
Lovington 2
5505
NNE
80467
80.47
< 1.30E-04
< 8.2E-05
Nadine CDP 2
376
NE
80467
80.47
< 1.30E-04
< 9.0E-05
Hobbs2 CCD
21653
ENE
80467
80.47
< 7.6E-05
< 9.0E-05
1.EDE	- Effective Dose Equivalent
2.	The CAP88-PC code limits the predicted dose to within an 80 km radius. Because Lovington, Nadine, and Hobbs are slightly over 80 km from the
WIPP release point, their dose calculations will be considered as 'qualified' estimates.
3.	Calculations are on a radial grid divided in concentric sectors and further divided in smaller compass directional subsectors. The source point is at
the center. The EDE for a population center is within the boundaries of a specific sector.
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