B Reactor Museum AssociationB Reactor Museum AssociationAuthor: Michele S. Gerber, Ph.D., Facility Operations Division, Westinghouse Hanford Company, April 22, 1993 (approved for public release May 19, 1993)
As soon as Project CG-600 was completed in 1960, C Reactor resumed its role as the chief test facility at HW. In early 1961, the overall power level was raised to 2,310 MW at 105-C. At the same time, a group of 20 process tube channels was overbored (enlarged) by 550 mils each, in order to be able to hold oversized I&E fuel elements. About 1,000 such elements, of 1.991-inch O.D. as compared to the 1.474-inch O.D. of regular I&E fuel elements, were manufactured in the 306 Metallurgical Development Facility in December 1960. The purpose of this production test was to increase plutonium production by increasing the fuel conversion ratio. In other words, HW operators wanted to determine whether the greater uranium mass of these oversized slugs, as compared to the relatively constant mass of the jackets, would boost plutonium production per unit of irradiation time. If the experiment succeeded and if overboring were completed in all channels of the six oldest reactors, site scientists believed that they could increase product output by 15 to 18 percent. A second benefit of the test at C Reactor, however, was that it allowed straightening of at least some of the badly bowed process channels in the pile. The overbored block in C Reactor was increased to encompass 40 process channels later in 1961. However, the existence of this unusual configuration caused abnormalities in the flux and temperature patterns within the reactor, and a greater number of fuel ruptures and equilibrium scrams (automatic shutdowns) occurred in 1962. By that time, experiments with smooth-bore process tubes and projection fuel elements had taken precedence over the overbore test, and overboring was not extended to the full reactor nor to other HW reactors.
In mid-1961, C Reactor was deemed so important to the HW production and developmental testing program that a proposal was submitted by HW management to build a mock-up of the pile inside the 186-D Building. Site officials believed that pre-assembly training and sequencing trials for important, upcoming experiments could save many hours of shutdown time in the reactor itself. However, this proposal was not funded by the AEC. Likewise, early 1960's proposals to build a hot cell for the examination of failed process tubes, and a "C-1 Loop" at C-Pile, were rejected by the AEC. The C-1 Loop would have been a high temperature, high pressure, recirculation-cooled facility for the irradiation of non-fissionable metallic samples. However, many other repairs, upgrades, and modifications did take place at 105-C. In 1961, the nitric-acid based, dummy and poison slug decontamination facility, first tested at C-Pile in 1954-1955, was completed (see Section 5.13). Soon, noise abatement equipment had to be added to the slug sorter. At nearly the same time, noise abatement materials also were installed in the 190-C Process Pump House including acoustical pads on the walls of the pump room and basement, and acoustical enclosures around the process pump motors. Also in 1961, a poison spline coiler was emplaced on the "C" elevator of C Reactor, with a recessed spline tank in the elevator pit. This equipment was similar to that installed at B Reactor at the same time (see Section 4.9). Concurrently digital outlet water temperature monitoring instrumentation, as well as water pressure monitoring equipment designed to reduce spurious reactor scrams were emplaced at C-Pile. Again, the devices were similar to those installed at B Reactor (see Section 4.4).
During 1961 and 1963, the same two last ditch coolant systems improvements that were completed to serve B Reactor also augmented the coolant backup that was available to C Reactor. The larger pumps installed in the 182-B Building to increase the export water flow capacity gave added protection to C-Pile, and the air inlet valves installed in both the 105-B and 105-C Buildings reduced the chances of water hammer and negative pressure in the export water system (see Section 4.8). In 1962, the steel railings and floor grating on the "C" elevator at C Reactor were replaced with lighter-weight aluminum parts, as the installation of operational "C-D" equipment had increased the weight loads on the "C" elevator beyond design capacity. During 1963, new emergency brake systems were installed on the hoisting shafts of the "C" and "D" platforms, and in 1966 the elevators at C-Pile underwent further upgrades. These improvements included the emplacement of still newer emergency air operated brakes, air compressors, synchro-differential protection, new synchronizing shafts, emergency lights, a graphic control panel, platform fence, mesh and bumper repairs, cable counterweight adjustment, and associated electrical and piping work.
As HW entered the mid-1960's, C Reactor still was considered to be one of the foremost production and testing machines at the Site. Therefore, it continued to be possible to obtain upgrades that sometimes were denied to the five older reactors. In December 1962, C-Pile's numerical power level limits were removed, and process tube outlet temperature limits were substituted. This step was deemed necessary to control accelerating tube and fuel element corrosion. The following year, in another effort to prevent the ruinous corrosion, the pH for process water in 105-C was dropped to 6.6. Still, in 1965, the removal of ruptured fuel elements cost 2,500 man-hours at C Reactor. The hotter operating temperatures and increased power levels and throughput also caused particular deterioration of effluent systems. In late 1962, the 107-CW retention basin was repaired, as leakage of effluent was undermining the basin structure. Holes and cracked weld seams were covered with new weld plates, the voids under the facility were filled with gravel, and several baffle plates were removed to the burial grounds. In 1963, the packing in 17 expansion joints in the C-Pile effluent piping system was replaced, after accumulated radioactive sludge and corrosion products were sandblasted and chemically dissolved. Leakage through the old packing had allowed the backflow of contaminated vapors into rear reactor work areas and outside of the 105-C Building. In 1964, an inspection of the C Reactor far downcomer showed that it was cracked in approximately 46 places, with the cracks ranging up to 76 inches in individual length and totalling 60 linear feet. The near downcomer, according to pile operators, was "assumed to be in a like condition." Additionally, "severe deterioration," including exposed aggregate and reinforcing bars, was found in the two effluent expansion boxes serving the downcomers. The degeneration of these facilities was attributed to vibration caused by the huge masses of coolant flowing through the effluent piping. Late that year, repairs were performed that included new welds, reinforcement with stainless steel channels, and perforation of downcomer vent piping to reduce water hammer. Complete replacement of the dual downcomers, estimated at $500,000, was considered too costly.
The following year, cracks were discovered in the C Reactor retention basins, amounting to 160 linear feet in the 107-CW structure and 100 linear feet in the 107-CE facility. Once again, these breaks had caused soil fissures and voids to form, to the extent that contamination spreads were almost constant and road wash-outs were possible in the vicinity. Additionally, according to reactor personnel corrosion in the piping that led from 105-C to the 107-C basins and in the diversion box, had "resulted in considerable flow of water to the outside ground." Repairs with flexible elastic sealers and angle-iron flanges were made to the retention basins in September 1965, at the same time that a 25-foot stretch of the diversion box wall was replaced with new, high-density concrete. Non-corrosive packing material also was applied to the piping at the entrance to the diversion box. In the summer of 1966, additional repairs were made to new breaks, holes, and corroded areas in the 107-C retention basins, diversion boxes, and piping.
Instrumentation upgrades and other improvements similar to those that occurred at B Reactor in the mid-1960's also took place at C-Pile. The gamma monitoring rupture detection equipment was upgraded in 1963, with the replacement of rear face sample lines and the addition of heat exchangers, automatic flow regulators, isokinetic flow and shutoff valves, and new cooling water supply and drain lines to the sample cells. Like those at B Reactor, the automatic flow regulators malfunctioned and had to be replaced in 1964 (see Section 4.10). The octant-type, linear power rate-of-rise instrumentation, installed in C-Pile on a "stop-gap" basis in 1958, was upgraded with a new system in 1965. It consisted of fifteen resistance thermal detectors (RTDs) emplaced in the rear face piping to measure the rate at which effluent tube temperatures changed. Wires from each RTD were connected to a junction box mounted on top of the reactor's rear face piping, and a cable then was run to a display panel in the control room. The following year, additional minor modifications completed the project.
In 1964 and 1965, the corroded interiors of the 190-C clearwells and the 183-C reservoirs were chemically cleaned, sandblasted, and then double-coated with a vinyl sealer paint. This work was similar to a concurrent project to upgrade the 190-B clearwells (see Section 4.9). At the same time, the four-engine, diesel-powered emergency backup pumping system, and the additional steam turbine pump excessed from the 182-H Building, were emplaced in the 182-B Building (see Section 4.8). These increases in pumping capacity augmented the last ditch cooling systems of both B and C Reactors. A new 20-inch, concrete reinforced pipe was run from the 182-B facility into the valve pit of 105-C, to carry the potential tertiary coolant flow.
By early 1966, C Reactor faced many of the same problems and constraints as did 105-B. DR, F, and H Reactors already had been shut down and the deactivation of D-Reactor was scheduled for 1967. That would leave only B, C, KE, and KW Reactors active among the single-pass piles at HW. Clearly, KE and KW were the newest of the old reactors (not considering N-Reactor, which was very new), and so 105-KE and 105-KW could be expected to receive most of the upgrades funding that was available. By that time, both B and C Reactors faced accelerating systems deterioration, including the fact that graphite distortion was so severe that flexible VSRs had been installed in 1963. A January 1966, maintenance work forecast for the coming year identified 19,466 man-hours worth of projects needing attention at C Reactor, not counting major upgrades to the effluent lines and to the "D" platform. Both of the latter endeavors would be undertaken by construction subcontractors, and so were not counted in the total man-hours needed by regular reactor service personnel. Among the key improvements needed at the 14-year old reactor were those affecting the Ball-3X system, the HCRs and VSRs, the front face hardware (especially the process tube caps), water treatment and filtration systems, pumping units, Panellit gauges, confinement and rear fog spray systems, and, as always, corroded process tubes. Additionally, the gas system required the installation of a helium leak detection system, and the neoprene seals and gas bellows, already preserved beyond their normal life spans by rubber foam treatments, needed replacement.
During the period 1966-1968, some important upgrade projects were funded at C Reactor and in the 100-B/C Area. The grounding of the 2,400-volt power systems in the 100-B/C Area in 1966 and 1967, of course, offered added safety to C Reactor electrical systems (see Section 4.10). Likewise, the increased raw water pumping capacity that was afforded in 1966 when the 181-B/C Building received two 600-HP pumps and motors excessed from the 181-H River Pump House, benefitted both B and C Reactors (see Section 4.11). Again, fire protection improvements added to the 100-B/C Area in 1967 gave augmented safety in many specific facilities, including the C Reactor SWP clothing storage rooms, lunch room, and miscellaneous storage rooms (see Section 4.10). That same year, the erection of new security fencing and fence lighting for the 100-B/C Area effectively reduced the total size of the 100-B and 100-C exclusion areas by three-fifths, and tightened overall security (see Section 4.11). Additionally, the 1967 improvements to the last ditch cooling system, made possible by the replacement of an older turbine drive for the steam pumps in the 181-B/C Building with a diesel engine drive excessed from 100-D Area, assisted both B and C Reactors (see Section 4.11).
In 1968, the front work area fog spray system, long promised and planned for all of the HW reactors, finally was installed at C, KE, and KW piles. The project, intended to provide additional safety and the confinement of volatilized radionuclides in case irradiated fuel rods should be ejected and should burn at the reactor's front face, actually was Phase IV of the Reactor Confinement Program -- Project CGI-791 (see Sections 4.7 and 5.15). It was stopped at the oldest five Hanford piles. Also in 1968, another 44-tube overbore and reactor modernization test facility was installed at C Reactor. Its objective was to evaluate fuel and hardware performance, and to accumulate physics data, with a one-inch enlargement in each of the experimental process tubes. At the same time, equipment necessary to renovate the C Reactor VSRs and sleeve their channels with new graphite was procurred. However, the shut down order that came in April 1969, prevented these upgrades from taking place.
By this time, the operators of C Reactor, like those at all of the other production units still operating at HW, were searching intensively for alternate methods of effluent disposal. With Washington, Oregon, and U.S. Public Health Service officials studying and criticizing Columbia River effects of reactor coolant disposal, C-Pile scientists tried different solutions. In 1967, they planned and scoped a 2,000-foot canal stretching inland from the reactor toward the Gable Mountain vicinity. Its purpose was to have been to transport hot effluent away from the river and into artificial inland lakes for slow percolation to groundwater. However, the inland lake concept had many flaws, and eventually it was dropped (see Sections 3.8 and 4.17).
Instead, a radioiodine-to-river monitoring system was installed at C, KE, and KW piles in 1968 and 1969. According to the HW reactor operating contractor at that time, "the fission product iodine 131 is the most significant from the standpoint of human exposure...Thus the purpose of the...monitoring system is to provide a rapid radioactivity analysis of effluent water discharged to the river...so that the appropriate warnings can be transmitted to downstream Columbia River water users following an abnormal release of fission products." The equipment consisted of stainless steel sample lines connected from the 107-C retention basins to an iodine rate meter (IRM) and an iodine integrating monitor (IIM). Both of the latter instruments were scintillation crystal, photomultiplier assemblies. The IRM measured gamma activity directly from effluent flow, and the IIM monitored activity as effluent samples were drawn through a miniature solvent extraction apparatus. Both devices displayed their results on a chart in the reactor control room, and an audible alarm accompanied the system. The front area fog spray system and the radioiodine-to-river monitoring devices were the last safety or instrumentation upgrade projects completed at C Reactor. Proposals for intermediate range exponential rate instrumentation for B, C, D, KE, and KW reactors were rejected in 1965 (see Section 4.10).
During the years after Project CG-600, C Reactor had only a few serious, uncontrolled contamination events. In November 1960, a localized contamination spread occurred inside 105-C Building areas and onto personnel, during an irradiated sample transfer out of the D test hole. The following month, a larger contamination spread occurred when a cask being shipped from C-Pile to the 300 Area was not properly wrapped and was not rendered airtight. Radioactive contamination was diffused over the exterior of the cask, the truck, and the driver. The same April 6, 1962, power loss that affected the other HW reactors also deprived C-Pile of the power source for its primary coolant pumps. However, the secondary coolant system worked well, and the two and one-half minute primary outage did not damage reactor systems. Six months later, rapid increases in process tube temperatures were experienced in one section of C Reactor, causing an enriched fuel element to rupture. The incident brought about revisions in cold startup rate-of-rise increases and a renewed drive to improve the sub-critical monitoring instrumentation (see Sections 6.2 and 6.4). In November 1963, outlet temperatures on 34 process tubes located near or in the overbore test facility in C-Pile exceeded operating temperature and rate-of-rise limitations during a cold startup. The cause was determined to be insufficient temperature monitoring during a period of augmented control rod movement and flux shifts.
Other problematic events occurred during contaminated waste burials in the 100-C Area, and/or while retention basins or other reactor systems were dried out and exposed for repair. One such high radiation reading resulted from incompletely buried waste or from extraordinarily hot waste in the 105-C burial ground in June 1961. In 1963, a test loop assembly bearing irradiated chemicals was removed from the C Reactor core, pulled through a hole in the south wall of the 105-C Building, and buried approximately 300-400 feet south of that facility. The assembly read approximately 100 R/hr at the time of its burial, but it is not known if a localized, or generalized, contamination spread occurred as a result of this burial.
Another diffusion of contamination, this time into the 105-C outer rod room, corridor, lunch room, and several other areas, took place in July 1966, when air pressure was used to blow water out of the HCR cooling tubes. The irradiated water transferred the contamination out of confined zones. In January 1968, a contaminated work bench in the C Reactor maintenance shop spread contamination onto the maintenance log book and thence onto the clothing of five employees. These employees subsequently wore their clothing home, thus initiating a full radiation occurrence investigation. The original cause of the radiation spread was above normal contamination on tools used to remove an aggravated, ruptured fuel element and process tube on December 31, 1967. Nearly ten years later, and two years after C Reactor had been shut down, the last known radioactive release event occurred in the 100-C Area. Particulate filters were being changed out of frames from the N-Reactor exhaust containment system. The work was being performed in unused space in the 190-C Building. Proper radiological controls had not been established, and particulate contamination from the filter frames escaped into the facility.
In September 1966, an unplanned chemical release of huge proportions occurred from the 189-B Refrigeration Building. The latter facility was used to store sodium dichromate solution before it was added to the process water feed tank in the 183-C Building. Inadvertently, a transfer pump in the 189-C Building was left running for two days, allowing the escape of 140,000 pounds of sodium dichromate solution to the Columbia River. The in-river concentration levels reached the point, according to Hanford environmental scientists, that some residents of Richland and Pasco "were exposed to concentrations between 100 and 150 ppb (parts per billion) of hexavalent chromium in their drinking water." When city officials were notified of the spill, sanitary supply water pumps in Richland, Pasco, and Kennewick were shut off for periods ranging from 7 to 29 hours.
On April 14, 1969, the Richland Operations Office of the AEC received a telegram from its Washington, D.C. headquarters that "C Reactor operation should be terminated as soon as practical this month, and the reactor should be placed in standby condition suitable for restart on 18 months notice." The deactivation date was set for April 28, but shutdown actually occurred three days earlier, due to an indication of a serious fuel rupture. At the same time, the decision was made to place 100-B Area on permanent lay-away status. Several key determinations made at this time necessitated systems changes in the 100-B/C Area. The irradiated fuel storage basins of both B and C Reactors continued to operate, awaiting the processing of their own slugs in the 200 Areas, as well as receiving and holding irradiated fuel from KE and KW Reactors. The only other facilities that continued to function were the Metal Examination Facility located in the 105-C Building, the Critical Components Examination Facility in the 108-B Building, the export water system that pumped from 182-B to the 200 Areas, and the utility services for the above facilities (including fire, sanitary, and filtered water systems). In order to provide for water flow through and from the irradiated fuel storage basins, the 107-CW retention basin also was continued in service.
The 107-B and 107-CE retention basins and their associated facilitis were stabilized early. They first were washed down with high pressure water, and sealant was applied to the surfaces to affix contamination. The baffles in the 107-CE tank were cut off and laid on the basin floor, and then 12-24 inches of dirt were placed on the bottom of each deactivated retention facility. Flows to these basins were valved off and redirected through sluice gates to the 107-CW basin. The two burial sites for sludge and baffles from the 107-B basin, one just to the north of the facility and one just to the south, already were posted as containing underground radioactive material. Their status was not changed. Additionally, two open cribs had been used to absorb unusual effluents from the 107-B and 107-C basins. Refuse and trash lying in the 107-B crib was burned, and then fill dirt and rocks were placed in both cribs to control contamination. The manhole lids on some of the effluent diversion boxes and piping were left partially open, because some air flow was required to preserve the system. The pump at the outlet end of the 107-B basin was drained and deactivated, along with the sprinkler system around all of the effluent basins. Barricades with permanently affixed radiation signs then were erected to enclose the entire 107 complex. The emplacement of fill dirt, rocks, and concrete markers for all other 100-C cribs and burial grounds was completed in 1970.
The 184-B Power House was deactivated quickly, necessitating the installation of transformers from other deactivated reactor areas in the 182-B and 183-B Buildings. Electric service to these transformers was supplied from the 2,400-volt circuit breakers in the 182-B and 183-B switches. A total of 65 electric heaters were installed in the 181-B River Pump House, pump and switchgear rooms of the 182-B Building, partitioned areas and pump rooms of the 183-B Building, metal storage basins in both the 105-B and 105-C Buildings, the first floor of the 108-B Building, the valve pit under the 1902-B high tank, and in the control room, switchgear room, metal examination facility, and associated service spaces within the C Reactor structure. Fire detection equipment, fire protection sprinkler systems, and electric sirens for warning purposes also were installed in various areas of the 105-B, 105-C, 182-B, 183-B, and 108-B facilities. However, the shutdown of KW-Reactor in early 1970, and the pending shutdown of KE-Reactor, led to the decision to deactivate, and not to emplace a sprinkler system, in the 105-C Metal Examination Facility. The crucial export water system to the 200 Areas was kept in operation through electric-driven motor pumps in the 182-B Building. At the deactivation of B and C Reactors, a diesel-driven pump was installed to replace the backup steam-driven turbine pump.
The important, initial deactivation operations at C Reactor, performed within the first few weeks of the shutdown order, were similar to those carried out in 1968 at B Reactor (see Section 4.20). They consisted of the following procedures:
Throughout the summer of 1969, the cleanout of contaminated trash and small equipment pieces continued at the 105-C Building. Many cartons and even truckloads were disposed in the C Burial Grounds. The 100-B/C Area fallout shelter, which had existed in the basement of the 190-C Building, likewise was emptied. In the autumn, the Corrosion Product Transport Facility, a small recirculating test loop in C Reactor, was relocated to KE-Reactor. In the spring of 1970, Columbia River elevation recording equipment located in the 181-B Building and in the Allard Pumping Station (a pre-Hanford Site irrigation pump house located between B and KW Reactors) was taken out of service. These actions, along with the deactivation of the Metal Examination Facility at the same time, closed out the most substantial production support activities in the 100-C Area.
In early 1971, after all required deactivation project work had been completed, a thorough radiological survey was made of the 105-C facility. All accessible areas were found to be within acceptable criteria for release from radiation zone status except for certain areas that were distinctly posted. Among the latter areas of heaviest contamination were the Ball-3X tunnel, the discharge area, the inner rod room, the X levels, the storage tank for irradiated 3-X balls located under the rod rack of the reactor, and the shielding cave south of the 105-C Building.
Substantial D&D programs were begun in the 100-C Area about six years after the shutdown of C Reactor. In 1975, oil was removed from the pump reservoirs in the 190-C Building, and one year later the disposal trench associated with the 107-C Retention Basin was stabilized with the emplacement of a two-foot cover of clean earth. During 1978 and 1979, the 183-C sedimentation basins were demolished, with the concrete walls broken up and buried in the basin cavity. In 1983, the reactor ventilation stack (the 116-C structure) was demolished and buried in place. A two-year D&D program conducted in 1984 and 1985 stabilized the 105-C irradiated fuel storage basin in the same manner as a similar project undertaken at the 105-B basin (see Section 4.21). The 8-10-foot heel of contaminated water was removed, processed, and released according to the criteria of that period. The fuel buckets and other miscellaneous solid objects were buried as contaminated waste, and the basin sludge was collected and stored under protective conditions in the transfer area. A fixative then was applied to the remaining contamination on the basin walls. In 1984, preparations for the dismantling of the 117-C Filter Building were begun, with the removal and burial of filters and equipment. Internal surfaces of the structure then were washed with decontamination rinses. The building itself was taken down in 1989, and the debris was buried in place. In 1990, asbestos lagging was removed from piping inside and outside of established radiation zones in the 105-C Building.
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