# Background

## Overview of Site Operations

In 1946, Congress created the U.S. Atomic Energy Commission (AEC) to
administer the nuclear programs created for the World War II Manhattan
Project. AEC needed new production capacity for nuclear weapons
materials used in national defense and, in November 1950, AEC selected a
location in South Carolina for the Savannah River Plant. Covering about
300 square miles (780 km^2^), the site was chosen because of its low
population density, large supply of water, freedom from major floods and
storms, and other factors (1).

SRS is located about 19 miles (32 km) south of Aiken, South Carolina,
and about 22 miles (36 km) southeast of Augusta, Georgia. It borders the
Savannah River for about 17 miles and comprises parts of Aiken,
Barnwell, and Allendale Counties in southwestern South Carolina. Figure
2-1 shows the general location of SRS.

The Savannah River Plant was designed, constructed, and operated for the
AEC by E.I. duPont de Nemours and Company (DuPont). Construction began
in 1951 (2). The basic plant was completed within five years and
included five nuclear reactors, two chemical separations plants, and
numerous laboratories and support facilities. The primary mission was
production of ^239^Pu and tritium. SRS bombarded fuel and targets
containing ^238^U and ^6^Li with neutrons in the nuclear reactors, and
recovered the ^239^Pu and tritium from the fuel and targets at the
separations facilities. DuPont continued operation of the plant until
1989 when operation was taken over by the Westinghouse Savannah River
Company. At that time, the site was renamed the Savannah River Site
(Phase II).

As production continued, the need for specific materials waned. As a
result, site facilities gradually ceased operation until the primary
defense-related mission ended in 1992. Since that time, certain
activities continue to manage waste, conduct environmental restoration
activities, and perform new missions (2).

Table 2-1 summarizes the SRS facilities of main importance for this
study, and shows the principal SRS areas and facilities. Most are
located in a rough circle in the approximate center of the site.[^1] SRS
contains two large ponds, Par Pond and L-Lake, and is drained by five
major streams feeding into the Savannah River: Upper Three Runs Creek,
Four Mile Branch, Pen Branch, Steel Creek, and Lower Three Runs Creek.
With the exception of Lower Three Runs Creek, all of these streams empty
into the Savannah River Swamp bordering the east side of the Savannah
River.

![](media/image1.wmf){width="6.44375in" height="6.163194444444445in"}

Figure 2‑1 General Location of SRS

![](media/image2.wmf){width="5.3277777777777775in"
height="6.209722222222222in"}

Figure 2‑2 Principal SRS Areas and Facilities

Table 2‑1 Principal Areas and Facilities

+-----+--------------+----------------+-------------------------------+
| Ar  | Facilities   | Dates          | Notes                         |
| eas |              |                |                               |
+=====+==============+================+===============================+
| 100 | R-Reactor    | 1953-1964      | Reactors used heavy water as  |
|     |              |                | a neutron moderator and       |
|     | P-Reactor    | 1954-1988      | primary coolant. L-Reactor    |
|     |              |                | operated from 1954 to 1968,   |
|     | C-Reactor    | 1955-1985      | and from 1985 to 1988.        |
|     |              |                | K-Reactor was the last        |
|     | K-Reactor    | 1954-1988      | operating reactor.            |
|     |              |                |                               |
|     | L-Reactor    | 1954-1968      |                               |
|     |              |                |                               |
|     |              | 1985-1988      |                               |
+-----+--------------+----------------+-------------------------------+
| 200 | H-Area       | Completed      | Facilities for chemical       |
|     | Chemical     | November 1954  | separation and purification   |
|     | Separations  |                | of plutonium (Pu), tritium    |
|     |              | Completed July | (^3^H), and other products    |
|     | F-Area       |                | from irradiated targets and   |
|     | Chemical     | 1955           | fuel. Also used for recovery  |
|     | Separations  |                | of tritium from weapons       |
|     |              |                | reservoirs.                   |
+-----+--------------+----------------+-------------------------------+
| 300 | M-Area Fuel  | Completed      | Produced reactor fuel and     |
|     | and Target   | January        | target assemblies for         |
|     | Production   |                | irradiation in reactors.      |
|     |              | 1953           |                               |
+-----+--------------+----------------+-------------------------------+
| 400 | D-Area Heavy | First          | Concentrated heavy water from |
|     | Water Plant  | operating by   | Savannah River.               |
|     |              | October 1952;  | Reconcentrated heavy water    |
|     |              | full capacity  | after contamination with      |
|     |              | by May 1953    | light water in reactors.      |
+-----+--------------+----------------+-------------------------------+
| 600 | E-Area Waste | First          | Burial grounds located in     |
|     | Management   | disposals in   | E-Area between F-and H-Areas. |
|     |              | 1953           | Still in use.                 |
+-----+--------------+----------------+-------------------------------+
|     | CMX and TNX  | Completed 1953 | Technical support, pilot      |
|     | Facilities   |                | plant development and         |
|     |              |                | training. Located near D-Area |
|     |              |                | Heavy Water Plant.            |
+-----+--------------+----------------+-------------------------------+
| 700 | A-Area       | Opened with    | Administrative offices.       |
|     |              | site           | Includes Savannah River       |
|     | Ad           |                | Technology Center.            |
|     | ministration |                |                               |
+-----+--------------+----------------+-------------------------------+
| S   |              |                |                               |
| our |              |                |                               |
| ce: |              |                |                               |
| (   |              |                |                               |
| 3). |              |                |                               |
+-----+--------------+----------------+-------------------------------+

### D-Area: Heavy Water Production and Processing

Some of the first facilities to be constructed were those producing
heavy water for use in the reactors. The Extraction Plant, which
operated until 1981, concentrated heavy water[^2] from a natural level
in river water (about 0.015 percent) to a concentration sufficient for
reactor operations. The Rework Unit and the Distillation Plant removed
light water that, over time, would contaminate the heavy water in the
production reactors. Additional facilities included a laboratory, a
facility to clean drums used for heavy water storage and transportation,
and a coal-fired powerplant (3).

Because tritium[^3] is created from deuterium by neutron bombardment,
concentrations of tritium in the reactor moderator built up over time.
Consequently, the processes used to reclaim reactor moderator discharged
tritium into the air and surface water.

The largest source of tritium released to air from D-Area was the Rework
Unit, where releases to air occurred from leaks from the Rework Unit
pump room and from the exhausts from the area used for storage of
recovered heavy water. Releases also occurred from the drum-cleaning
facility and the laboratory (1).

The Rework Unit was also responsible for the largest source of tritium
released to surface water from D-Area. Typically, waste distillate was
collected in tanks before sampling and discharge to cooling water
effluent that drained to Beaver Dam Creek (1).[^4] The tritium in the
waste distillate was normally in concentrations that were too low for
practical recovery (1).

### M-Area: Reactor Materials

Fuel and target elements for irradiation in the SRS reactors were
fabricated in the M-Area. Major facilities located in the M-Area were
the Alloy Extrusion Unit, the Uranium Metal Element Fabrication Unit,
the Target Extrusion Unit, and the Metallurgical Laboratory. All uranium
for fuel and targets was received from offsite sources (1).

Activities generated airborne and liquid effluents containing uranium
isotopes. Air treatment procedures differed depending on the operational
processes within each M-Area building. Initially, liquids containing
uranium were discharged to Tims Branch and pond beds adjacent to M-Area
(1).[^5] As of 1977, about 50 percent of the discharged uranium had
settled in the stream and beds and had "not reached the main stream
leading to the river" (1). After late 1976, most liquids were discharged
to the M-Area settling basin (1).

Reactor Areas summarizes the dates of operation of the five SRS
production reactors. All reactors used heavy water as a neutron
moderator and primary coolant. All were housed in buildings constructed
of heavy concrete to provide radiation shielding to personnel. Reactor
systems and auxiliaries included the primary and secondary coolant
systems, the component-handling systems, and the disassembly basins (1).

###### Coolant Systems

The primary coolant system consisted of heavy water circulating through
the reactor core. In each system, coolant entered a plenum and then
flowed through the reactor core. Heated coolant then passed through
heat-exchangers where heat from the fission process was transferred to a
secondary coolant system (1).

At each reactor, water bled from the primary coolant system was
circulated through a water-treatment system to maintain ionic purity of
the coolant and to reduce radiation exposures to personnel.[^6] Typical
water treatment equipment included filters, deionizers, and evaporators.
An offshoot from the deionizer effluent passed through a distillation
unit that removed light-water impurities from the heavy-water coolant
(1).[^7]

Table 2‑2 Summary of Reactor Operations

+-------+-------------+------------------------------------------------+
| Re    | Dates of    | Comments                                       |
| actor | Operation   |                                                |
+-------+-------------+------------------------------------------------+
| C     | 1955-1985   | Shut down in 1985.                             |
+-------+-------------+------------------------------------------------+
| K     | 1954-1988   | Shut down in 1988, but operated briefly in     |
|       |             | 1992. In 1993, it was put in cold standby as   |
|       |             | the Nation's tritium source. Shut down         |
|       |             | permanently in 1996.                           |
+-------+-------------+------------------------------------------------+
| L     | 1954-1968   | Shut down for upgrades in 1968. Restarted in   |
|       |             | 1985. Shut down in 1988.                       |
|       | 1985-1988   |                                                |
+-------+-------------+------------------------------------------------+
| P     | 1954-1988   | Shut down in 1988.                             |
+-------+-------------+------------------------------------------------+
| R     | 1953-1964   | Shut down in 1964.                             |
+-------+-------------+------------------------------------------------+
| So    |             |                                                |
| urce: |             |                                                |
| (2).  |             |                                                |
+-------+-------------+------------------------------------------------+

The secondary coolant system consisted of water from the Savannah River.
River water was pumped to reservoirs located in the reactor areas, and
from the reservoirs passed through the reactor heat exchangers. As
reactor thermal power gradually increased from 1954 to 1962, [^8]
additional secondary cooling capacity was achieved by measures such as
doubling the number of heat exchangers used in the secondary coolant
system, by increasing river-pump capacity, and by the construction of
Par Pond in 1958 (3).

Par Pond is a 2,700-acre reservoir formed by damming Lower Three Runs
Creek. Pond water pumped to the P- and R-Reactors was returned to Par
Pond,[^9] allowing increased delivery of river water to the L-, P-, and
C-Reactor secondary cooling systems. Until 1985 and 1988, respectively,
effluent cooling water from C- and K-Reactor heat exchangers flowed back
to the river via onsite streams. Until 1988, cooling water from
P-Reactor continued to flow to Par Pond. In 1985, SRS formed L-Lake by
damming Steel Creek. SRS used L-Lake as a heat sink for L-Reactor when
it operated from 1985 through 1988 (3).

###### Component-Handling System

The component-assembly area of a reactor building was used to receive
fresh fuel from the 300-M Area and to discharge irradiated fuel from the
reactor[^10] to a reactor disassembly basin (1).[^11]

###### Disassembly Basin

A disassembly basin is a deep pool of water used to temporarily store
fuel and miscellaneous reactor components removed from the reactor.
During the 1950's and 1960's, irradiated material stayed in the
disassembly basins for less than nine months. In later years, the
storage period was longer (3).

#### Air and Water Treatment and Effluent 

Releases of radionuclides to air and water varied over time depending on
modifications to reactor operations, reactor equipment, and air- and
water-treatment systems. Releases to air and water also resulted from
occasional problems with equipment.

###### Air

Principal sources of airborne release at reactor areas included the
reactor building, disassembly basins, and seepage basins (3).

Exhaust from each of the process areas in a nuclear reactor was routed
through an air treatment system consisting of moisture separators,
filters, and charcoal beds to remove elemental iodine vapor and gaseous
iodine compounds.[^12] Exhaust was discharged from a 200-foot stack (1).
Radionuclides released from the reactor building included tritium and
fission and activation products, including iodine isotopes and ^41^Ar.
Tritium was released mainly from evaporation of the moderator (3).[^13]

Exhaust from the disassembly basin area was discharged to the air from a
roof vent. Releases mainly consisted of tritium in water evaporating
from the pool surface. Ground-level release of tritium occurred from
evaporation of seepage basin water (3).

###### Water

**Table 2-3** summarizes liquid effluent procedures for each reactor.
During operation, some of the radionuclides contaminating the reactor
coolant were transferred to secondary coolant water from leakage of the
heat exchangers. Thus, coolant water discharged to surface waters
contained tritium and other radionuclides.

The disassembly basins were additional sources of contaminated liquid
effluent. To ensure visual clarity and maintain personnel exposure
levels at acceptable levels, the basins were purged with river water.
Until the mid 1960's, basin purge water was continuously discharged to
site streams along with secondary cooling water. Sand filters were added
to the disassembly basins in the early 1970's, and continuous purging to
site streams ceased although periodic purging continued from 1970 to
1977. In 1978, SRS began to discharge water from periodic purges to
reactor seepage basins. These seepage basins were constructed at all
reactor basins during the second half of 1957 primarily for disposal of
water generated from vacuum-cleaning the disassembly basins (3).

### F- and H-Separations Areas

Chemical separations facilities at SRS consist of two main complexes: F-
Area and H-Area. Each complex contains a shielded separations building
divided into two parallel "canyons" as well as auxiliary facilities that
include a waste concentration and storage system, seepage basins,
powerhouses, and service facilities. F-Area contains a laboratory, the
plutonium metallurgical building, and the Plutonium Fuel Form Facility
(PuFF). H-Area contains the tritium process buildings, the Receiving
Basin for Offsite Fuels (RBOF), and the Resin Regeneration Facility
(RRF).

Table 2‑3 Summary of Liquid Discharge Procedures at SRS Reactors

+--------+-------------+----------------------------------------------+
| R      | Operation   | Liquid Effluents                             |
| eactor |             |                                              |
+--------+-------------+----------------------------------------------+
| R      | 1953-1964   | To Lower Three Runs Creek, Par Pond, and one |
|        |             | seepage basin                                |
+--------+-------------+----------------------------------------------+
| P      | 1954-1988   | To Steel Creek, Par Pond, and three seepage  |
|        |             | basins                                       |
+--------+-------------+----------------------------------------------+
| C      | 1955-1985   | To Four Mile Creek and three seepage basins  |
+--------+-------------+----------------------------------------------+
| K      | 1954-1988   | To Pen Branch and two seepage basins         |
+--------+-------------+----------------------------------------------+
| L      | 1954-1968   | To Steel Creek, L Lake (built in early       |
|        |             | 1980's by damming Steel Creek), and a        |
|        | 1985-1988   | seepage basin                                |
+--------+-------------+----------------------------------------------+

Source: (3).

###### Separations

Operations at either of the two separations facilities typically began
with dissolution of the cladding from the irradiated fuel or targets,
followed by dissolution of the declad materials, generally in nitric
acid. This process evolved volatile fission products such as iodine
isotopes. The solution was then sent through a series of solvent
extraction cycles. The first solvent extraction cycle stripped the
product (e.g., plutonium and uranium) from the fission products. The
product was then purified in subsequent chemical processes. Fission
products (and some residual plutonium and uranium) from the first
solvent extraction cycle were routed to the high-level waste tanks (3).

###### Tritium Recovery

The tritium facilities in the H-Area consist of three buildings (i.e.,
232-H, 234-H, and 238-H) where tritium was separated from irradiated
lithium-aluminum targets, further purified, and packaged (1).

###### Receiving Basin for Offsite Fuels

This H-Area building houses fuels from offsite reactors. Fuels are
received and either stored or cut and packaged for reprocessing. In
addition, the RBOF received special nuclear fuels from SRS and offsite
research reactors. It is now shut down (1,3).

###### Resin Regeneration Facility

This H-Area facility received ion-exchange resin beds and filters from
reactor areas for regeneration (1).

###### Metallurgical Building

This F-Area facility was used to fabricate components for uranium,
neptunium, and plutonium reactor elements (1).

###### Plutonium Fuel Form Facility

This F-Area facility manufactured Pu-238 heat source fuel forms (3).

###### Analytical Laboratory

This F-Area facility supplied radioanalytical services to the entire
plant except for the Savannah River Laboratory (1).

###### Waste Concentration and Storage

High-activity waste liquids from separations operations were
concentrated and stored in tanks. Most notably, high-level liquid wastes
from the solvent extraction process were pumped to large underground
tanks located in "farms" in each separations area. As of 2002, 37
million gallons of waste remained stored in 49 tanks in 2 tank farms
(4).

#### Air and Water Treatment and Effluents

###### Air

Both separations buildings were ventilated by systems that directed air
from clean areas to areas that were contaminated. Ventilation air was
passed through filters before discharge to stacks. The main stacks for
both separations areas were 200 feet tall. The F-Area Canyon was also
equipped with an auxiliary stack for dissolver off-gas as well as a
160-foot stack for air ducted from the plutonium processing areas (1).

Air from the three tritium facilities (232-H, 234-H, and 238H) was
discharged through tall stacks (1)

Off-gas from the RBOF building was filtered and discharged to air
through 53-foot stacks. In addition, gases collected from fuel-cask
opening or fuel-cutting operations were passed through charcoal and HEPA
filters before discharge (1).

###### Water

Radioactive contamination released to surface water mainly came from two
sources: coolant water for the separations process vessels and seepage
basins. One coolant-water system, used for areas that were unlikely to
become contaminated, recirculated coolant water through a cooling tower.
A second system was a once-through system: water was normally discharged
to Four Mile Creek if measured levels of contamination were sufficiently
low. If water from either system contained contamination above
prescribed limits, the water was diverted to seepage basins constructed
in each of the two separations areas. If seepage basin limits were
exceeded, the water was sent to retention basins for storage pending
treatment (1).

Three seepage basins were used at each separations area. Liquid
discharged into the seepage basins seeped through the ground until it
discharged to a seepline draining to Four Mile Creek. After 1988, when
the Effluent Treatment Facility for the separations areas became
operational, the F- and H-Area seepage basins were not used (3).

### Waste Management Areas

Activities at SRS have generated large quantities of radioactive wastes,
most of which were either disposed or stored onsite. Disposal of
radioactive wastes has occurred at 20 locations within SRS. The
high-level waste is stored in several underground tanks located in the
F- and H-Areas (3). These wastes are not of particular interest to this
study due to the low levels of radionuclide release from waste storage
and disposal operations to air and surface water. However, liquid
effluents that have been released to seepage basins are of interest.
Seepage basins have been discussed above.

### Additional SRS Facilities

Several additional facilities and support areas exist on the SRS and
provide small to negligible discharge of radionuclides to water or air.

#### A-Area: Administrative Area

The Administrative Area contains organizations and facilities that
support SRS operations. The only facility that historically contributed
radionuclides to air and water was the Savannah River Technology Center
(SRTC), which was established in 1951 as the Savannah River Laboratory.
For its first few decades of operation, the SRTC fabricated fuel-element
prototypes, targets containing radioactive oxides, and sealed
radioactive sources. It also performed research and development of
separations processes. Airflow through contaminated areas was filtered
and vented through either a 100-foot or a 160-foot stack. If within
prescribed concentration limits, low-activity contaminated liquids were
transferred to laboratory seepage basins; otherwise, they were
transported to F-Area for treatment. High-activity-level liquids were
transferred to F-Area for storage (1,3).

Other facilities in the A-Area include the U.S. Department of Energy
site office and the Savannah River Ecology Laboratory.

#### TNX and CMX Semiworks 

Although considered part of the SRTC, the TNX and CMX Semiworks are
located near the Savannah River next to the 400-D Area. The TNX
facilities were used to study chemical-processing problems and test
production-scale equipment. Tests were conducted using natural uranium
or other surrogates. In later years, the facility researched and
developed waste treatment processes. The CMX facility conducted
non-nuclear tests of the hydraulic systems of the SRS reactors until it
shut down in 1984 (3).

## Principal Radionuclides Released During SRS Operations

During 39 years of operation, SRS released a variety of radionuclides
into air and surface water. For the SRS dose reconstruction effort, the
Phase II report provides estimates of the release of those radionuclides
determined to be most significant for public health concerns (3).

Challenges faced in the Phase II study included incomplete records of
radionuclide release, gaps in monitoring data, and questions about early
radiation detection and analysis equipment. Releases of radionuclides
from times when data were available were scaled in Phase II to times
when data were not available based on knowledge of the processes that
resulted in the release. SRS procedures for monitoring releases from
plant operations were reviewed as was the SRS environmental monitoring
program. Estimates of release for some radionuclides were adjusted from
those reported by SRS (3).

To focus the effort, a two-step screening analysis was performed using a
screening process set forth by the National Council on Radiation
Protection and Measurements (6). From the first step of the screening
process, the Phase II study identified a list of key radionuclides that
had been released into the air and water from SRS operations. The key
radionuclides released to air were ^241^Am, ^41^Ar, ^14^C, ^137^Cs,
^3^H, ^129^I, ^131^I, ^238^Pu, ^239,240^Pu, ^103,106^Ru, ^89,90^Sr, and
uranium. The key radionuclides released to surface water were ^137^Cs,
^60^Co, ^3^H, ^129^I, ^131^I, ^32^P, ^238^Pu, ^239,240^Pu, ^89,90^Sr,
^35^S, ^99^Tc, uranium, ^91^Y, ^65^Zn, and ^95^Zr/Nb. From the second
step of the screening process, which considered possible exposure
pathways in more detail, the Phase II study identified two smaller sets
of radionuclides released to the air and water for further detailed
analysis. These radionuclides consisted of ^131^I, ^3^H, ^41^Ar, ^129^I,
^239,240^Pu, and uranium released to air, and ^137^Cs, ^3^H, ^89,90^Sr,
^60^Co, ^32^P, ^131^I, and uranium released to water (3).

For the Phase III effort, the source term provided in the Phase II
report was closely reviewed and refined. [Chapters
5](../Chapter_05_Ready%20for%20CDC%20031405.doc) and
[7](../Chapter_07_Ready%20for%20CDC%20031405.doc) discuss these
adjustments in detail. The radionuclide release data presented in the
Phase II report could not be used directly in the Phase III effort due
to the following three major concerns:

1.  The Phase II report did not provide annual release estimates for all
    key radionuclides. For some radionuclides, the report provided a
    36-year total source term.

2.  The Phase II report did not provide release estimates for many
    radionuclides for the years 1990 through 1992.

3.  The Phase II report included estimates for some radionuclides as
    aggregated quantities (e.g., ^89,90^Sr, uranium). However, this
    format was incompatible with the requirements of the GENII code.

The estimates provided in the Phase II report were refined to determine
annual release estimates of each of the key radionuclides for all 39
years of the study[^14]. To do so, data in SRS reports (7) was examined.
For key radionuclides cited in the Phase II report as aggregated
isotopes (e.g., ^89,90^Sr, uranium), the radionuclides were separated
into their isotopic constituents based on an understanding of the
processes that generated the isotopes.[^15] In addition, some of the
data in SRS reports were presented in terms of undifferentiated activity
(i.e., unidentified \[gross\] alpha and unidentified \[gross\]
beta-gamma activity). For these data, ^239^Pu was assumed for reported
unidentified alpha activity and ^90^Sr was assumed for reported
unidentified beta-gamma activity. Finally, information was reviewed
about the likely chemical forms of the released radionuclides, a
consideration needed for certain portions of the analysis. See [Chapters
5](../Chapter_05_Ready%20for%20CDC%20031405.doc) and
[7](../Chapter_07_Ready%20for%20CDC%20031405.doc), and [Appendix
B](../Appendix_B_ready%20for%20CDC%20031405.doc), for additional
information about partitioning assumptions and procedures.

### F- and H-Separations Areas

Chemical separations facilities at SRS consist of two main complexes: F-
Area and H-Area. Each complex contains a shielded separations building
divided into two parallel "canyons" as well as auxiliary facilities that
include a waste concentration and storage system, seepage basins,
powerhouses, and service facilities. F-Area contains a laboratory, the
plutonium metallurgical building, and the Plutonium Fuel Form Facility
(PuFF). H-Area contains the tritium process buildings, the Receiving
Basin for Offsite Fuels (RBOF), and the Resin Regeneration Facility
(RRF).

Table 2-4 lists the radionuclides and whether they were released via the
air or surface water pathway. [Appendix
B](../Appendix_B_ready%20for%20CDC%20031405.doc) provides lists of the
quantities released of each radionuclide through air and water pathways
as a function of year.

Table 2‑4 Radionuclide Release Pathways

  -----------------------------------------------------------------------
  Radionuclide            Released to Air         Released to Surface
                                                  Water
  ----------------------- ----------------------- -----------------------
  ^3^H (tritium)          X                       X

  ^14^C                   X                       

  ^32^P                                           X

  ^35^S                                           X

  ^41^Ar                  X                       

  ^60^Co                                          X

  ^65^Zn                                          X

  ^89^Sr                  X                       X

  ^90^Sr                  X                       X

  ^95^Zr                                          X

  ^95^Nb                                          X

  ^99^Tc                                          X

  ^106^Ru                 X                       X

  ^129^I                  X                       X

  ^131^I                  X                       X

  ^134^Cs                                         X

  ^137^Cs                 X                       X

  ^144^Ce                                         X

  ^234^U                  X                       X

  ^235^U                  X                       X

  ^236^U                  X                       X

  ^238^U                  X                       X

  ^238^Pu                 X                       X

  ^239^Pu                 X                       X

  ^241^Am                 X                       
  -----------------------------------------------------------------------

> \*Source: (8).
>
> ^†^y = years; d = days; h = hours.

#### Iodine and other Beta-Gamma-Emitting Particles

Radioactive iodine and other beta-emitting-radionuclides were released
mainly from the separations areas. In particular, iodine and other
volatile isotopes evolved from dissolution of reactor fuels and targets.

Iodine releases included elemental iodine (I~2~) and organic iodides
(e.g., CH~3~I). The Phase II report observed that releases if iodine for
the early years of operation (through about 1961) contained significant
uncertainties. The Phase II estimates of ^131^I release included a
significant correction to release estimates provided by SRS[^16] (3).

Release of other beta-gamma-emitting isotopes also occurred, mainly from
the F- and H-Areas. These isotopes included ^89,90^Sr, ^95^Zr/Nb,
^103,106^Ru, ^137^Cs, and ^141,144^Ce (3).

#### Activation Products

Activation products are generated when neutrons produced during fission
interact with reactor materials such as control rods and structural
members, with fuel and target cladding, with air within the reactor, and
with impurities and anti-corrosion chemicals in the moderator. Table 2-5
lists the principal activation products generated in SRS reactors (3).
The principal activation product of concern for release into the air is
^41^Ar. Because argon is a noble gas, it was released from SRS
facilities (primarily reactors) without capture by the air treatment and
filtration systems.

Table 2‑5 Characteristics of Activation Products

  ------------------- ----------------------------- ---------------------
  Radionuclide        Primarily Produced From       Half-Life

  ^32^P               ^31^P                         14.3 days

  ^35^S               ^35^Cl                        87.3 days

  ^41^Ar              ^40^Ar                        1.83 hours

  ^51^Cr              ^50^Cr                        27.7 days

  ^60^Co              ^59^Co                        5.27 years

  ^65^Zn              ^64^Zn                        244 days

  Source: (3).                                      
  ------------------- ----------------------------- ---------------------

#### Alpha-Emitting Radionuclides

Alpha-emitting radionuclides―principally isotopes of uranium and
plutonium―were released to air at SRS primarily from the M-Area, the
reactors, and the separations facilities. Measured releases were small
from M- Area and the reactors, and larger from the separations
facilities. Most plutonium emissions occurred from 1955 to 1969 from F-
and H-Area stacks. Uranium releases were largest during 1955, 1968, and
1969 from H-Area stacks; and during 1955, 1956 and throughout the 1960s
from F-Area stacks (3).

### Release of Radionuclides to Surface Water

#### Tritium

The major sources of tritium released to surface water were reactor and
separations area effluents discharged to streams and seepage basins.
Lesser quantities of tritium were released to surface water from the
D-Area (3).

#### Iodine and other Beta-Gamma-Emitting Particles

The major sources of iodine, ^137^Cs, and other beta-gamma-emitting
particles released to surface water were reactor and separations area
effluents discharged to streams and seepage basins (3).

#### Activation Products

The major sources of activation products released to surface water were
reactor and separations area effluents discharged to streams and seepage
basins (3).

#### Alpha-Emitting Radionuclides

Alpha-emitting radionuclides released to surface water included isotopes
of uranium and plutonium. Uranium isotopes were released from M-Area and
the separations areas. Plutonium releases to surface water came mainly
from the separations areas (3).

## SRS Environmental Setting

This section provides a background discussion of human and environmental
factors within the vicinity of SRS that are of interest to this study.
Primary references are (1), (3), (4), and (10).

### Population and Land Use 

The area was sparsely populated when SRS was created. Although the only
towns on the plant site were Ellenton (population 600) and Dunbarton
(population 251), the communities of Leigh, Hawthorn, Robbins, and
Meyers contained isolated groups of families (1). About 6,000 persons
comprising 1,500 families (10) were relocated. Some moved to New
Ellenton, which was established north of the SRS boundary to replace
Ellenton (4).

Construction of SRS employed a peak force of 38,500 workers (4). The
operating work force initially numbered 5,000 workers (1), climbed to
7,500 by 1980, and totaled nearly 26,000 by 1992 (4). As of 2000, it
numbered 14,000 (4).

When SRS was sited, about 67 percent of the land was forested and about
33 percent was pasture and cropland. The main crops were cotton and corn
(1). Abandoned fields gradually became pine forests. Current land use on
SRS is about 56 percent pine forest, 35 percent hardwood, 7 percent in
SRS facilities and open fields, and 2 percent water (10). Except for
three roads and a rail line near the edge of the site, public access to
SRS is restricted to environmental studies, guided tours, and controlled
deer hunts (10). Adjacent to SRS, about 21 percent of the land is
devoted to agriculture and about 70 percent comprises forests, wetlands,
water bodies, and unclassified, predominately rural lands. Less than 8
percent is urban or built-up (10).

### Environmental Characteristics

#### Meteorology and Climatology

The climate in the region of SRS is subtropical, characterized by long,
warm, and humid summers and short, mild winters. The average annual
temperature at SRS is 64.7^o^F and the average precipitation is 49.5
inches. The driest season is fall, with an average monthly rainfall of
3.3 inches; the wettest season is summer, with an average monthly
rainfall of 5.2 inches. The average annual relative humidity is 70
percent. The average daily maximum relative humidity is 91 percent, and
the average daily minimum is 45 percent. Winds currently blow most
frequently from the northeast and southwest. Current SRS atmospheric
conditions have been classified as unstable about 56 percent of the time
(10).[^17]

#### Geology and Hydrology

##### Regional Geology 

SRS is located on the Upper Atlantic Coastal Plain. Most soils at SRS
are sandy over loamy or clayey subsoil. Annual erosion rates for
regional soils, including cropland, range from 1.5 to 2.0 kg/m^2^/yr.
Two soil profile horizons are commonly noticed. The upper horizon (A
Horizon) typically consists of structureless fine- to medium-grain
quartz sand up to 3 meters thick. The lower horizon (B Horizon) contains
iron and aluminum compounds and may range in thickness from 0.6 to 3
meters (10).

##### Ground Water Hydrology 

The shallow ground water on the site is contained within the Floridian
Aquifer System, comprising the lowermost Gordon aquifer unit, the Gordon
confining unit, and the uppermost Upper Three Runs aquifer unit that
contains the water table (4,9). The water table varies from ground
surface to a depth of about 100 feet. In F- and H-Areas, the
ground-water velocity ranges from a few hundredths of a foot per day to
one foot per day near streams (1).

The shallow aquifers beneath the industrial areas that make up about to
10 percent of the SRS have been contaminated with industrial solvents,
metals, tritium, and other constituents used or generated at SRS. In
general, DOE does not use these aquifers for SRS process operations
although there are a few low-yield wells in the Gordon Aquifer and the
lower zone of the Upper Three Runs Aquifer. The shallow aquifer units of
the Floridian System discharge to SRS streams and eventually the
Savannah River (4).

Despite the contamination in some of the shallow aquifers on the site,
"there is no data available to suggest that groundwater containing
radionuclides has migrated off the SRS to the surrounding communities"
(12). Rather, as stated above, localized contaminated ground water on
the SRS discharges into onsite streams that ultimately discharge to the
Savannah River (12).[^18]

##### Surface Water Hydrology 

Operations at SRS caused large withdrawals of cooling water from the
Savannah River as well as discharge of heated water to onsite streams.
Thermal discharges were reduced after construction of a cooling tower to
support K-Reactor operation and L-Lake to support L-Reactor operation
(3).

Five major tributaries to the Savannah River drain SRS: Upper Three Runs
Creek, Four Mile Branch, Beaver Dam Creek, Steel Creek, and Lower Three
Runs Creek. Figure 2-3 shows the major river and stream system at SRS.
These streams meander for several miles through SRS and---except for
Lower Three Runs Creek--- through the Savannah River Swamp before
emptying into the river. A sixth stream, Pen Branch, joins Steel Creek
in the Savannah River Swamp. One stream in the northeast area of SRS
drains to the Salkehatchie River. The natural flow of SRS streams ranges
from about 10 cubic feet per second (cfs) in smaller streams to 245 cfs
in Upper Three Runs Creek (4). For several years, coolant and effluent
discharges greatly increased flow in these streams above their natural
rates. Savannah River flow in 1995 averaged about 10,000 cubic feet per
second at SRS (4).

F- and H-Areas are situated on a divide that separates drainage into
Upper Three Runs Creek and Four Mile Branch. About half of each area
drains into each stream. The F- and H-Areas are drained by Upper Three
Runs Creek to the north and west and by Four Mile Branch to the west.
The surface aquifer for both F- and H-Areas discharges at seeplines
along both Four Mile Branch and Upper Three Runs Creek (3,4).

![](media/image3.wmf){width="6.495833333333334in"
height="6.5993055555555555in"}

Figure 2‑3 Major River and Stream Systems at SRS

Upper Three Runs Creek is the only major tributary on SRS that has not
received thermal discharges (4). One of Upper Three Run Creek's
tributaries―Tim's Branch―received (at Road C) effluents from A-Area and
M-Area. Steed\'s Pond, located on Tim's Branch just north of Road 2, was
a mixing and settling pond for A-Area and M-Area wastes (3,4).

Four Mile Branch originates near the center of SRS and flows southwest
before emptying into the Savannah River (4). It drains much of the F-,
H-, and C-Areas and received C-Reactor cooling water about 0.5 miles
south of Road 3. It flows parallel to the Savannah River behind natural
levees and enters the river through a breach downriver from Beaver Dam
Creek. In its lower reaches, Four Mile Branch broadens and flows via
braided channels through a delta formed by the deposition of sediments.
Downstream from the delta, the channels rejoin into one main channel
(3,4).

Steel Creek and Lower Three Runs Creek both received significant
quantities of reactor effluents. Steel Creek received discharges from
the L- and P-Reactor Areas before Par Pond was built in 1958. K-Reactor
effluent from Pen Branch was discharged to Steel Creek via the swamp
through one major and one or more minor streams about a half mile above
Steel Creek\'s mouth (3). Lower Three Runs Creek received some discharge
from the R-Reactor area before 1958. Overflow from Par Pond carried
runoff from the northeast portion of the plant and any contaminants
leaking to the reactor secondary cooling water system (3).

The mouths of Steel Creek, Pen Branch, and Four Mile Branch have built
sedimentation deltas from erosion of stream banks caused by stream
channels carrying many times their natural flows. In the late 1950's and
early 1960's, L- and P-Reactor effluents increased the flow in Steel
Creek from its natural level of 35 cfs to 250-400 cfs (3).

The Savannah River Swamp borders the river for about 10 miles (16 km)
and has an average width of about 2.4 km (1.5 miles). From 1958 to 1967,
the swamp flooded about 74 days per year. The river historically
overflowed its channels when flows were equal to or exceeded 438 cubic
meters per second. The highest levels in the Savannah River typically
occur in winter and spring, and the lowest levels occur in fall and
winter (3).

### Ecology

Because public use of the Savannah River Site was restricted, and
because the production and support facilities occupy only a fraction of
the total site area, SRS is a natural preserve for biota typical of the
southeastern Coastal Plain.

#### Vegetation 

The site is about evenly divided between the Aiken Plateau and three
Coastal terraces: Brandywine, Sunderland, and Wicomico. The Aiken
Plateau is hilly and deeply dissected by streams and contains extensive
growths of scrub oak and longleaf pine. Soils are sandy in the Aiken
Plateau and sandy loam in the terraces (1).

Little timber management occurred before Federal acquisition of the
site. Generations of logging had depleted stands of timber except for
floodplain hardwoods, which were not generally exploited. Much of the
site consists of managed pine forests. Dry, sandy areas of the site are
typically covered with scrub oak and contain longleaf pine, turkey oak,
blue jack oak, black jack oak, dwarf post oak, and huckleberry. Trees
available in moister soils along streams and on old floodplains include
tulip poplar, beech, sweetgum, willow oak, swamp chestnut oak, water
oak, loblolly pine, and ash. Bald cypress and tupelo gum are dominant
trees in the Savannah River Swamp (1).

#### Mammals 

Mammal populations―particularly deer―increased rapidly after closure of
the site to the public on December 14, 1952. By the mid 1970's the deer
population grew to more than 20 deer per square mile or about 5,000 to
8,000 deer on the plant site. Controlled hunts open to the public were
begun in 1965. Thousands of deer have been taken in public hunts. In
addition, feral hogs are present. These were domestic animals that
reverted to a semiwild state after abandonment in 1952. Similar to deer,
the hogs grew sufficient in number to warrant hunts. About 125 were
taken between 1969 and the mid 1970's (1).

Additional wild mammals common to the site include mice, rats, shrews,
gray and red foxes, raccoons, wildcats, striped skunks, opossums, fox
squirrels, and beavers (1).

#### Birds 

Biologists have identified more than 200 species of birds on the plant
site. Of note is the wild turkey population, which was small at the time
the site opened. However, wild turkey populations have increased as the
result of a program initiated in 1972 that used the site as a breeding
ground for stocking other parts of the States. In addition, large
numbers of coots and ducks spend winters on and near the site (1).

#### Aquatic Animals 

Diverse populations of reptiles and amphibians exist onsite, including
numerous species of turtles, lizards, snakes, salamanders, frogs, and
toads. Alligators have been seen in ponds and streams. Onsite fish
species include largemouth bass, black crappie, bluegill, redbreasted
sunfish, flat bullhead, and blueback herring (1).

Hundreds of species of aquatic insects have been identified on SRS
(e.g., a study conducted from 1976 to 1977 identified 551 species in the
Upper Three Runs Creek system including species and genera that were new
to science). Otherwise, populations of fish and aquatic insects in some
of the onsite streams were adversely affected during SRS's nuclear
production period due to thermal loadings, principally from reactor
discharge of heated cooling water. But as operational changes (e.g.,
reactor shutdown) reduced the volumes of heated water discharged to
onsite streams, the fish and aquatic insects have returned (4). For
example, since C-Reactor was shut down in 1985, macroinvertebrate
communities have recovered in Four Mile Branch and, in some parts of the
stream; have resembled those in other nonimpacted SRS streams.
Macroinvertebrate communities of Four Mile Branch currently tend to show
more diversity in downstream than in upstream reaches (4).

## References

1\. U.S. Energy Research and Development Administration (ERDA). Final
environmental impact statement: waste management operations. ERDA-1537.
Aiken, South Carolina: Savannah River Plant. September 1977.

2\. Westinghouse Savannah River Company (WSRC). Historical highlights @
SRS. April 23, 2002 \[cited 22 July 2003\]. Available from URL:
[*http://www.srs.gov/general/about/hilits.htm*](http://www.srs.gov/general/about/hilits.htm).

3\. Till JE, et al. Savannah River Site environmental dose
reconstruction project, Phase II: source term calculation and ingestion
pathway data retrieval, evaluation of materials released from the
Savannah River Site*.* RAC Report No. 1-CDC-SRS-1999-Final. Risk
Assessment Corporation (RAC). April 30, 2001.

4\. U.S. Department of Energy (DOE). Savannah River Site high-level
waste tank closure environmental impact statement. DOE/EIS-0303. Aiken,
South Carolina: Savannah River Operations Office. May 2002.

5\. WSRC. DOE laboratory fact sheets. Savannah River Technology Center
\[cited July 18, 2003\]. Available from URL:
[*http://www.sc.doe.gov/production/er-07/page2a26.html*](http://www.sc.doe.gov/production/er-07/page2a26.html).

6\. National Council on Radiation Protection and Measurements (NCRP).
Screening models for determining compliance with environmental
standards. NCRP Report No. 123. Bethesda, Maryland: NRCP. 1996.

7\. Cummins CL, Hetrick CS, Martin DK. Radioactive releases at the
Savannah River Site 1954-1989. WSRC-RP-91-684. 1991.

8\. FGR-13. Eckerman, K. F., et al. Cancer Risk Coefficients for
Environmental Exposure to Radionuclides. Federal Guidance Report No. 13.
EPA 402-R-99-001. Oak Ridge National Laboratory and U.S. EPA Office of
Radiation and Indoor Air. September 1999.

9\. Heffner J.D. Comments on CDC's final draft report on Phase II of the
Savannah River Site dose reconstruction project (U). ESH-EMS-99-0461.
May, 11 1999.

9\. Cook JR, et al. Closure plan for the E-Area low-level waste
facility. Rev. 2. WSRC-RP-2000-00425. Aiken, South Carolina:
Westinghouse Savannah River Company, Savannah River Site. September 2,
2002.

10\. Gibbs A. Fifty years of transuranic waste at Savannah River Site
(from production to cleanup). WSRC-MS-2002-00902. Aiken, South Carolina:
Westinghouse Savannah River Company. 2002.

11\. Moore MS. Critical pathway assessment of the Savannah River Site,
Aiken, South Carolina. Environmental Surveillance and Oversight Program.
01CP001. South Carolina Department of Health and Environmental Control:
May 2002.

12\. Christensen EJ, Gordon DE, eds. Technical summary of groundwater
quality protection program at Savannah River Plant. Volume I and II.
DPST-83-829. 1983.

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[^1]: SRS facilities are identified by a system, using numbers and
    letters that reference them to a particular onsite area containing a
    complex of related or supporting operations. For example, each of
    the two chemical separations areas is identified by a letter of the
    alphabet (F and H Areas), and each building or structure within an
    area is numbered in accordance with a century nomenclature (i.e.,
    the reactor areas are the 100-Areas, the separations areas are the
    200-Areas, and so forth). A structure in one of the 100-Areas
    (reactor areas) is identified by a number in the 100's, a structure
    in one of the 200-Areas is identified by a number in the 200's, etc.

[^2]: Each molecule of water consists of two hydrogen atoms and one
    oxygen atom. One or both of the hydrogen atoms in heavy water
    contains a neutron in the nucleus in addition to a proton. A
    hydrogen atom containing a neutron and a proton in the nucleus is a
    deuterium (D).

[^3]: A tritium (T) atom is a radioactive atom of hydrogen containing
    two neutrons and a proton in the nucleus.

[^4]: This creek flows to the Savannah River Swamp and then follows a
    meandering route through the swamp to the river, mixing with a
    portion of the flow from Four Mile Branch.

[^5]: Tim's Branch empties into Steeds Pond about 1-1/2 miles from the
    300-Area. Overflow from Steeds Pond drains into Upper Three Runs
    Creek, which empties into the Savannah River.

[^6]: Operation of the reactor resulted in contamination of the coolant
    with radionuclides due to neutron activation of coolant, cladding,
    and reactor components; corrosion of cladding and components; and
    leakage of fission products from fuel.

[^7]: Buildup of light water in the primary coolant system primarily
    resulted from exposure of the coolant to humid air within the
    system.

[^8]: The reactor thermal power, or heat output, is proportional to the
    rate of fission and the creation of fission products in the fuel.
    With higher rates of fission, higher reactor core densities of
    neutrons were achieved resulting in larger rates of production of
    tritium and other products.

[^9]: Before construction of Par Pond, cooling water from the heat
    exchangers was discharged directly into onsite streams.

[^10]: Control rods and other components were similarly charged into the
    reactor and discharged as needed.

[^11]: Also called a fuel and target storage basin or a fuel pool.

[^12]: This equipment was typical by the end of 1963 when all reactor
    ventilation systems had been fitted with charcoal beds and
    high-efficiency particulate filters. This air-treatment system was
    installed in R-, P-, and K-Reactors in 1962, and in the remaining
    two reactors the following year.

[^13]: Tritium built up due to neutron capture by deuterium and
    primarily released as either T~2~O or DTO.

[^14]: ^106^Ru, ^144^Ce, and ^134^Cs were added to the list of isotopes
    considered in Phase III for release to surface water. ^91^Y was
    deleted for release to surface water. Although ^91^Y was listed as a
    key radionuclide in the Phase II report, it actually did not pass
    the screening criteria used for either step of the Phase II
    screening analysis.

[^15]: In this report, ^89,90^Sr was partitioned into ^89^Sr and ^90^Sr,
    ^95^Zr/Nb was partitioned into ^95^Zr and ^95^Nb, and uranium was
    partitioned into ^234^U, ^235^U, ^236^U, and ^238^U. It was assumed
    that activity identified as ^239,240^Pu was all ^239^Pu, activity
    identified as ^103,106^Ru was all ^106^Ru, and activity identified
    as ^141,144^Ce was all ^144^Ce.

[^16]:

[^17]: More detailed historical information about wind speeds,
    directions, and stability classes are more difficult to obtain. Of
    interest to this report would be detailed meteorological data from
    the mid 1950's to the 1990's. SRS lacked a formal meteorological
    program until the early 1970's, leaving a gap of about 20 years in
    SRS-specific meteorological data.

[^18]: The Phase II report concludes, in Appendix J, that "although
    groundwater contamination from SRS releases may be a potential
    exposure pathway for the future, the evidence suggests that it did
    not impact offsite residents before 1992" (3).