16

and C-340, C-400, C-410, and C-420 could have

exposed maintenance mechanics to concentrated

inhalation and contamination hazards.

Several formal cascade improvement programs (CIPs)

and cascade uprating programs (CUPs) involving

replacement of major components to increase diffusion

process reliability, capacity, and efficiency started as early

as 1954. The second major CIP/CUP started in March

1973 and continued for eight years. This CIP/CUP process

involved cell by cell removal of compressors and

converters, process piping, and support system components

while the remainder of the cascades remained in operation.

After removal, compressors and converters were taken to

C-400 for disassembly, cleaning, and decontamination and

then to C-720, where they were modified and reassembled

prior to reinstallation. In addition to releases of UF6, these

disassembly activities exposed maintenance workers to

transuranics and fission products adhering to surfaces inside

the system and to trichloroethene (TCE) during degreasing

and decontamination. Workers could have received

significant radiation exposures by inhaling neptunium-237

dust. At the completion of the CIP/CUP activities,

converter and compressor disassembly remained a routine

operation.

Between March and May of 1977, C-340

underwent a slow and deliberate shutdown for an

indefinite period. During the shutdown period, which

lasted until the mid-1980s, Building C-340 was used as

a valve rebuilding shop and routine maintenance facility.

2.4 Unusual Occurrences and

Accidents

During its first 40 years of operation, PGDP

experienced numerous operational upsets, releases,

exposures, and other accidents. Documentation,

investigation, and reporting of these unusual events were

very inconsistent and infrequent until the initiation of

DOEís formal occurrence reporting systems in the late

1980s. One of the most frequent and notable unusual

events was the release of UF6

 gas into work areas or

the environment. The releases ranged from very small

amounts, commonly referred to as ìpuffs,î to significant

amounts that resulted in HF burns, and uranium intakes

requiring bioassay or medical attention for dozens of

workers. The sources of these releases included the

process system during system upgrade work, equipment

failures, and maintenance activities; cylinder connection

and disconnection activities at feed and withdrawal

stations; and process equipment disassembly during

shop maintenance activities in C-400 and C-720.

Several evaluation reports on UF6

 releases and their

effects, as well as other site documents, identified

approximately 50 UF6 releases, each in excess of 10

pounds of uranium. However, reviews of health physics

reports and the site quarterly progress reports from the

early 1960s revealed references to many hundreds of

releases of varying sizes (described often only as minor,

large, or major). These reports identified many

employees who were exposed from these releases and

required medical examinations and bioassay. Burns and

respiratory tract bleeding from exposures to or inhalation

of HF were frequent occurrences. Many health physics

reports indicated that these releases were not

documented in operations shift logs and were often not

addressed in the Plantís quarterly progress reports to

the AEC, which was the regulatory agency at that time.

At least 15 events were identified in the first ten

years of Plant operation that each released a minimum

of 100 pounds of uranium, with a 1960 event releasing

approximately 6,800 pounds and a 1962 event releasing

approximately 3,400 pounds. As better equipment was

installed and major system upgrade work ended,

operational practices improved and the number and

quantity of UF6

 releases decreased significantly. In the

1980s, reported releases were on the order of one to

five per month and were measured in grams instead of

pounds. The number of persons placed on recall for

bioassay decreased from 30 or more per month in the

1950s to one to six per year in the 1980s.

Other significant Plant events included a major fire

in Building C-310 in 1956, overexposure of two

maintenance mechanics to beta radiation, and an

explosion and fire in C-315 in 1978. Major releases

affecting groundwater included a spill of 17,000 gallons

of diesel oil migrating as far as 2 miles from the site

boundary via surface water and the identification of

C-337 Fire and Explosion - December 1962
17

significant volumes of TCE leakage from C-400 to the

site sewer system, discovered in June 1986. Three fatalities

were reported as a result of Plant events: an explosion and

fire in C-340 in 1962, electrocution of an electrical

maintenance trainee in 1977, and the suffocation of an

operator in the collapse of a coal bridge at the steam plant

in the 1970s. In addition, in June 1958, a release of HF

severely burned a worker who did not return to work.

2.5 Industrial Hygiene and

Radiation Protection

Programs for industrial hygiene and radiation

protection were in existence from the beginning of Plant

operation. Initial Plant training classes included theory

and protective actions for working with radioactive and

hazardous materials. There were policies and

procedures that addressed the radiological protection

of workers. PPE was provided and available to workers

and in work areas where hazards were deemed greatest

and protection was deemed necessary. The amount of

formal training given to employees diminished after Plant

startup, and much of the knowledge concerning both

operations and hazard communication and controls

resulted from on-the-job training of new workers by

more experienced personnel and by supervisors. Starting

in the early 1960s, job hazard analyses (JHAs) were

prepared for most work activities and addressed many

safety hazards, but not all JHAs adequately addressed

radiation protection. Safety committees and regularly

scheduled safety meetings, which included radiological

subjects, were important elements of the process of

hazard communication.

Non-radiation hazards, such as industrial and chemical

exposures (primarily HF), were evaluated and addressed

throughout the history of the Plant. The evolution of

awareness and the application of protection and controls

for significant hazards, such as asbestos and

polychlorinated biphenyls (PCBs), essentially paralleled

that of the regulatory bodies and general industry. Air

monitoring of hazardous job sites existed from Plant

startup, and health physics personnel monitored air and

surface contamination in work areas and recommended

additional or modifications to engineering controls or PPE,

if deemed necessary. As early as 1952, Plant health

physics personnel were aware of the potential hazards of

personnel contamination and instituted measures such as

monitoring work areas, providing company clothing, and

providing frisking devices for workers to monitor

themselves before eating or leaving work. However,

survey records from the early 1950s indicated that few

workers performed self-monitoring.

Identification of asbestos and PCB hazards did not

emerge until the 1970s or later. During the fourth quarter

of 1973, some of the first air samples for asbestos were

taken and sent to Oak Ridge National Laboratory

(ORNL) for analysis; however, no formal asbestos

program existed until 1987. During this period, OSHA

adopted 14 carcinogen standards. In 1975, preparations

were under way for a two-year program to provide

formal respiratory training on a sitewide basis. There

was less concern over worker exposure to PCBs through

absorption, and many workers wore PCB-contaminated

clothing. Some workers considered PCBs to be an

effective remedy for dry skin.

The health physics staff provided exposure

monitoring services, recommended training and

protective measures for supervisors, maintained

exposure and radiation measurement records,

administered a bioassay program, investigated air

samples and personnel exposures that were outside of

specifications, studied Plant hazards and needed

controls, and performed Plant environmental

monitoring. However, the size of the Health Physics

Section (i.e., two to six people during the first 37 years

of operation) limited the amount and effectiveness of

surveillance and monitoring of hazardous conditions and

activities for the approximately 1,200 to 2,500 people

in numerous and diverse work environments. While

line supervision had always been responsible for

implementing recommended controls and protective

measures, supervisory oversight and worker

implementation of PPE and related measures were

inconsistent. Non-compliant PPE use by workers can

in part be attributed to the pressures to maintain normal

process operations, a lack of knowledge and

understanding of the risks involved and why the

protection was needed, and the physical discomfort and

vision impairment associated with wearing PPE, such

as respirators, in hot, dirty environments.

Safety Equipment