4


Air Quality


I. BACKGROUND   §4.1

II. EXHAUST SYSTEM SAMPLING RESULTS   §4.2

Table 4-1: Most Significant Radionuclides Used During 1998

Table 4-2: US/EPA-Approved NESHAPs Compliance Strategy

Table 4-3: NESHAPs Building Exhaust Sampling and Monitoring Profile

Table 4-4: Summary of Radiological Air Emissions Released During 1998

Figure 4-1: Trends in Annual Tritium Releases from NTLF

III. AMBIENT AIR MONITORING RESULTS

A. Tritium   §4.3

Figure 4-2: Ambient Air Monitoring Network Sampling Locations

Table 4-5: Summary of Ambient Tritium Sampling

B. Gross Alpha/Beta   §4.4

Table 4-6: Gross Alpha and Beta Sampling Results from
                   Ambient Air Monitoring Network



§4.1      I. BACKGROUND

Berkeley Lab’s air monitoring program is designed to meet the following set of requirements:

NESHAPs and DOE Order 5400.5 authorize monitoring requirements for radiological air emissions, while DOE Order 5400.1 includes additional requirements for nonradiological air emissions.

Under present requirements, the Berkeley Lab air quality program measures only radiological components. Estimates of nonradiological air emissions use alternative methodologies (e.g., engineering calculations, record-keeping, and dose/risk modeling) to satisfy regulatory requirements. The comprehensive Environmental Monitoring Plan4 describes the basis and current scope of the air monitoring program at the Laboratory.

The air monitoring program consists of two separate elements: exhaust emissions monitoring and ambient air surveillance. Exhaust emissions monitoring measures airborne contaminants in building exhaust streams. Ambient air surveillance measures air contaminants in the outdoor environment.

Ambient air surveillance results alone cannot distinguish between Berkeley Lab, non-Berkeley Lab, and natural background emission sources. When combined with exhaust emissions monitoring results and local meteorological information, however, ambient air surveillance results can help characterize the impact of Laboratory activities on the surrounding environment. The number and placement of monitoring stations, as well as the parameters monitored and their frequency, are routinely reviewed to account for changes in Laboratory operations or external requirements.

§4.2      II. EXHAUST SYSTEM SAMPLING RESULTS

Berkeley Lab uses various radionuclides in its radiochemical and biomedical research programs. In addition, radioactive materials are generated from the operations of charged particle accelerators. Radionuclide releases from on-site building exhaust systems are usually in the form of vapor or gas. Releases in solid form as particulate matter are the least common form.

Table 4-1 contains the names and decay characteristics of the most significant radionuclides used at Berkeley Lab. Radioactive gases produced by accelerator operations are mainly short-lived radionuclides, such as carbon-11, nitrogen-13, oxygen-15, and argon-41.

Table 4-1      Most Significant Radionuclides Used During 1998*

 

Nuclide name
(atomic number)


Symbol

Principal radiation
types


Half-life

Carbon (6)
11C
positron/gamma20.5 minutes
14C
beta5730 years

Fluorine (9)

18F

positron/gamma

109.7 minutes

Hydrogen/Tritium (1)

3H

beta

12.28 years

Iodine (53)
123I
gamma13.1 days
125I
gamma60.14 days
131I
gamma8.04 days

Nitrogen (7)

13N

positron/gamma

9.97 minutes

Oxygen (8)
14O
positron/gamma71 seconds
15O
positron/gamma122 seconds

*For a complete list of radionuclides evaluated under NESHAPs regulations, see Radionuclide Air Emission Annual Report for 1998, found on Berkeley Lab’s EH&S Web site at http://www.lbl.gov/ehs/esg/index.shtml.

The NESHAPs regulations require source measurement if the potential dose, or exposure over time, from emissions exceeds 1.0 ´ 10–3 mSv/yr (0.1 mrem/yr).1 As discussed in §3.7, Berkeley Lab uses a comprehensive tiered strategy approved by US/EPA to satisfy this requirement. See Table 4-2. This strategy involves three distinct levels of assessment:

Table 4-2      US/EPA-Approved NESHAPs Compliance Strategy


Compliance category

Annual effective dose equivalent*
(mSv/yr)



Sampling/monitoring strategy

Noncompliant

AEDE > 0.1

Reduce or relocate source term and reevaluate before authorization.

I

0.1 > AEDE > 0.001

Continuous sampling with telemetry to central computer for half-life less than 100 hours and weekly analysis for half-life greater than 100 hours. (US/EPA approval required to construct or modify.)

II

0.001 > AEDE > 0.0005

Continuous sampling with weekly analysis.

III

0.0005 > AEDE > 0.0001

Continuous sampling with monthly analysis.

IV

0.0001 > AEDE > 0.00001

Sampled annually during project activity.

V

0.00001 > AEDE

No monitoring required. Inventory controlled by administrative methods (Radiation Work Authorization/Permit).

*AEDE

The number and location of sources under each assessment category change in response to the research at Berkeley Lab. All but one source are considered "small sources" of emissions under NESHAPs. The vast majority fall into compliance assessment Category V, which requires no monitoring. The 90 sources in this group adhere to strict inventory limits specified in individual work authorizations. Twenty-three locations use continuous sampling, including the only compliance Category I source on site (the tritium stack at Building 75). Three locations have more rigorous real-time monitoring systems to estimate emissions with radionuclide half-lives that are less than 100 hours. Table 4-3 lists the breakdown of source assessment by category for the reporting year.

Table 4-3      NESHAPs Building Exhaust Sampling and Monitoring Profile

Monitoring type


Method


Location

Real-time

Real-time monitoring of 11C, 13N, and 15O

Bldg. 88 accelerator exhaust

  Real-time monitoring of 11C, 13N, 15O, and 18F

Bldg. 56 Biomedical Isotope Facility accelerator exhaust
(2 locations)

Continuous

Sampling with weekly analysis

8 locations

 

Sampling with monthly analysis

15 locations

No monitoring

Inventory (administrative) control

90 locations

The stack monitoring program analyzed emission samples for five radiological parameters in 1998: gross alpha, gross beta, carbon-14, iodine-125, and tritium. As in past years, tritium in the form of tritiated water vapor was the predominant radionuclide emitted from Berkeley Lab activities. Tritium emissions totaling 4.26 × 1012 Bq (115 Ci) were measured during the year, with nearly all tritium emitted from the National Tritium Labeling Facility’s (NTLF) exhaust stacks. Table 4-4 provides the list of the most significant radionuclide air emissions from site activities for the year. For information on the projected dose from all radionuclide emissions, see chapter 10.

Table 4-4      Summary of Radiological Air Emissions
                     Released During 1998*

Nuclide

(Bq/yr)

% Total

H-3

4.26 ´ 10+12

99.1%

C-11

2.37 ´ 10+10

0.6%

F-18

1.30 ´ 10+10

0.3%

N-13

3.11 ´ 10+9

<0.1%

O-15

2.22 ´ 10+8

<0.1%

C-14

4.08 ´ 10+7

<0.1%

I-125

1.39 ´ 10+7

<0.1%

All others

4.88 ´ 10+5

<0.1%

Total

4.30 ´ 10+12

100.0%

*For a complete list of radiological air emissions, see NESHAPs Annual Report for 1998, found on Berkeley Lab's EH&S Web site at http://www.lbl.gov/ehs/html/env_protection.htm.



Tritium emissions rose in 1998 from the previous year because of a combination of increased research activity at the NTLF and an unplanned release of 1.30 × 1012 Bq (35 Ci) on July 24. In spite of this increase, emissions of tritium are still well below levels from the late 1980s and well below regulatory levels of concern. The most recent five-year average of 2.43 × 1012 Bq (65.8 Ci) is about 12% of the 1988 emissions level of 21.5 × 1012 Bq (580 Ci). A series of engineering and administrative controls enacted in the early 1990s reduced and maintained emissions to their current level. See Figure 4-1. Before the July incident, the NTLF did not have an unplanned release greater than 1.10 × 1012 Bq (30 Ci) in more than four years. The release was much less than the EPA reportable quantity of 3.70 × 1012 Bq (100 Ci) for tritium.5 For details on the July release, see §3.7.


Figure 4-1      Trends in Annual Tritium Releases from NTLF


              III. AMBIENT AIR MONITORING RESULTS

§4.3      A. Tritium

Berkeley Lab operated six monitoring sites in 1998 to determine levels of airborne tritium in the environment. Three of the locations were on site and three were off site, as seen in Figure 4-2. The sites were chosen based on known emission sources, local wind patterns, and proximity to off-site residential areas and facilities. Monitoring equipment at all sites continuously samples outdoor air at a constant rate. The sampling media are replaced and analyzed monthly.


Figure 4-2      Ambient Air Monitoring Network Sampling Locations

Table 4-5 summarizes the network’s atmospheric tritium concentrations for the year. Average and maximum concentration values are far below 1% of the allowable Department of Energy annual exposure standard for tritium in air.6 The 1998 ambient air results for the network are similar to the results from the previous year and well below levels measured as recently as 1995. For example, the annual average concentration at the highest reporting station, ENV-69, dropped from 24 Bq/m3 (650 pCi/m3) in 1995 to 1.72 Bq/m3 (46 pCi/m3) in 1998. Improved field sampling and analytical laboratory techniques are key reasons for this improvement. The 1998 results are also consistent with dispersion modeling results of stack emissions required by NESHAPs. See §10.5.

 

Table 4-5      Summary of Ambient Tritium Sampling


Station ID

Number of samples

Mean
(Bq/m
3)

Mean as percent
of standard
a

Median
(Bq/m
3)

Maximum
(Bq/m
3)

ENV-B13A

12

< 0.11b

< 0.11b

0.15

ENV-B13C

12

< 0.11b

< 0.11b

< 0.11c

ENV-B13D

12

0.12

0.003

< 0.11b

0.29

ENV-69

12

1.72

0.05 

0.94

8.91

ENV-85

12

0.26

0.007

0.12

1.52

ENV-LHS

12

1.72

0.05 

1.71

3.96

a Standard of comparison = 3.7 x 103 Bq/m3 (source: DOE Order 5400.5).
b Statistic was below the maximum MDA for this site.
c All results for this site were "nondetect."


§4.4      B. Gross Alpha/Beta

The ambient air sampling network also included a series of stations designed to measure gross alpha and gross beta levels in particulate emissions. This network complements the exhaust system sampling for the same parameters, discussed earlier in this chapter. The network consists of four monitoring sites: three sites on the main grounds of the Laboratory and a fourth site at the monitoring program’s most remote station, ENV-B13C. As with tritium sampling, the samplers draw air past collection media at a constant rate, with the media replaced monthly and samples analyzed by certified laboratories.

Table 4-6 summarizes gross alpha and beta results from sampling activities in 1998. Although DOE Order 5400.5 does not provide a standard for particulate gross alpha and beta radiation,6 several observations about these results are apparent:

These observations indicate that environmental impacts from the Laboratory’s radioactive releases of alpha and beta emitting isotopes to the atmosphere are negligible.

 

Table 4-6      Gross Alpha and Beta Sampling Results from Ambient Air Monitoring Network


Analyte


Station ID

Number of samples

Mean
(Bq/m
3)

Median (Bq/m3)

Maximum (Bq/m3)

Alpha

ENV-B13Ca

12

<1.1 × 10–4

<1.1 × 10–4

1.3 × 10–4

 

ENV-69a,b

12

<1.1 × 10–4

<1.1 × 10–4

<1.1 × 10–4

 

ENV-80a

12

<1.1 × 10–4

<1.1 × 10–4

1.4 × 10–4

 

ENV-81a

12

<1.1 × 10–4

<1.1 × 10–4

1.4 × 10–4

Beta

ENV-B13C

12

4.8 × 10–4

4.1 × 10–4

7.5 × 10–4

 

ENV-69

12

4.5 × 10–4

4.3 × 10–4

6.7 × 10–4

 

ENV-80

12

4.5 × 10–4

4.3 × 10–4

6.8 × 10–4

 

ENV-81

12

4.6 × 10–4

4.1 × 10–4

8.7 × 10–4

a Both the mean and median were below the maximum MDA for this site.
b All results for this site were "nondetect."