In-containment chemical decontamination system for nuclear rector primary systems

A nuclear reactor having a chemical decontamination system is provided in which every piece of decontamination equipment which processes radioactive materials is located within the containment chamber of the nuclear reactor. This decontamination system therefore presents advantageous safety benefits over an outside of containment system in the unlikely event of a leak of radioactive materials from the decontamination system.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to the field of decontamination of nuclear 
reactor primary systems. More specifically, it relates to a unique 
apparatus for integrating a chemical injection system, a clean-up 
subsystem and a resin replacement system into a nuclear reactor primary 
system for chemical decontamination of the entire primary system in which 
the process equipment which contacts radioactive materials are situated 
inside of the containment chamber. 
2. Description of the Prior Art 
The problem of excessive personnel exposures caused by high background 
radiation levels in a nuclear reactor primary system, such as in 
pressurized water reactor (PWR) systems, and the resultant economic cost 
of requiring personnel rotation to minimize individual exposure is 
significant at many nuclear plants. These background levels are 
principally due to the buildup of deposits of radioactive corrosion 
products in certain areas of the plant. The buildup of corrosion products 
exposes workers to high radiation levels during routine maintenance and 
refueling outages. The long term prognosis is that personnel exposure 
levels will continue to increase. 
As a nuclear power plant operates, the surfaces in the core and primary 
system corrode. Corrosion products, referred to as crud, are activated 
during transport of the corroded material through the core region by the 
reactor coolant system (RCS). Subsequent deposition of the activated crud 
elsewhere in the system produces radiation fields in piping and components 
throughout the primary system, thus increasing radiation levels throughout 
the plant. The activity of the corrosion product deposits is predominately 
due to Cobalt 58 and Cobalt 60. It is estimated that 80-90% of personnel 
radiation exposure can be attributed to these elements. 
One way of controlling worker exposure, and of dealing with this 
problematic situation, is to periodically decontaminate the nuclear steam 
supply system using chemicals, thereby removing a significant fraction of 
the corrosion product oxide films. Prior techniques had done very little 
to decontaminate the primary system as a whole, typically focusing only on 
the heat exchanger (steam generator) channel heads. 
Two different chemical processes, referred to as LOMI (developed in England 
under a joint program by EPRI and the Central Electricity Generating 
Board) and CAN-DEREM (developed by Atomic Energy of Canada, Ltd.), have 
been used for small scale decontamination in the past. These processes are 
multi-step operations, in which various chemicals are injected, 
recirculated, and then removed by ion-exchange. Although the chemicals are 
designed to dissolve the corrosion products, some particulates are also 
generated. One method of chemical decontamination, U.K. Patent Application 
No. GB 2 085 215 A (Bradbury et al.). There is little disclosure, however, 
of the methodology to be used in applying that chemistry to system 
decontamination. 
While these chemical processes had typically been used on only a localized 
basis, use of these chemical processes has now been considered for 
possible application on a large scale, full system chemical 
decontamination. Such an application is disclosed generally in co-pending 
application Ser. No. 07/621120, entitled "System For Chemical 
Decontamination Of Nuclear Reactor Primary Systems", and incorporated 
herein by reference. 
While some work has been done in the boiling water reactor (BWR) programs, 
the BWR scenarios examined by those in the field involved decontaminating 
fuel assemblies in sipping cans employing commercial processes at 
off-normal decontamination process conditions with little regard for the 
effects of temperature, pressure, and flow that would be mandated by an 
actual application of the process to the full RCS. 
The estimated collective radiation dose savings over a 10-year period 
following decontamination is on the order of 3500-4500 man rem, depending 
upon whether or not the fuel is removed during decontamination. At any 
reasonable assigning of cost per man-rem, the savings resulting from 
reduced dose levels will be in the tens of millions of dollars. 
As a result of the present examination of potential full system 
decontamination, and the resulting need for new sub-system methods, 
developments have been made by the assignor of this invention to use 
demineralizing resin beds in conjunction with the known chemical 
processes. Developments in resin replacement systems for the demineralizer 
resin beds have also been made by the assignor of this invention. These 
developments are set forth in co-pending application Ser. No. 07/621129, 
entitled "Clean-up Sub-system for Chemical Decontamination of Nuclear 
Reactor Primary Systems", and in 07/621130, entitled "Resin Processing 
System", which are both incorporated herein by reference. 
There exists a need for a design layout which incorporates these advanced 
full system decontamination systems and sub-systems and incorporates them 
into an existing or future reactor plant design. One such plant design 
would be an "in-containment" design in which the plant processing units 
which handle radioactive materials would be installed inside of the 
containment chamber. 
SUMMARY OF THE INVENTION 
The present invention is directed to a chemical decontamination system to 
be used in conjunction with a nuclear reactor primary system to achieve 
full primary system decontamination. More specifically, the present 
invention is directed towards a chemical decontamination system which is 
located primarily within a containment chamber. This "in-containment" 
system locates every piece of decontamination equipment which contacts 
radioactive materials inside of the containment chamber. Specifically, the 
systems which are contained within the containment chamber are the 
demineralizer system, the resin fines filter system, the spent resin 
storage tank system, and the sluice water system. 
The demineralizer system is comprised of a plurality of demineralizer 
vessels which are downstream of and flow coupled to the primary system. 
The resin fines filter system is comprised of a plurality of resin fines 
filters which are downstream of and flow coupled to the demineralizer 
vessels. 
The spent resin storage tank system is comprised of a plurality of spent 
resin storage tanks which are downstream of and flow coupled to said 
demineralizer vessels and which receive spent resin from the demineralizer 
vessels. The sluice water system is comprised of a sluice water supply 
tank which provides sluice water to the demineralizer vessels for removing 
the spent resin from the demineralizer vessels. 
It is an object of the present invention to provide a process design which 
allows for the connection of a chemical decontamination system into a 
nuclear reactor primary system to economically and chemically 
decontaminate substantially the entirety of the nuclear reactor primary 
system in which the decontamination system equipment which contacts 
radioactive material is located inside the containment vessel.

DETAILED DESCRIPTION OF THE INVENTION 
Certain aspects of the use of a full system chemical decontamination 
process to clean the primary reactor fluid system of radioactive "crud" is 
disclosed in co-pending Application Ser. No. 07/621130, entitled "System 
for Chemical Decontamination of Nuclear Reactor Primary Systems," 
application Ser. No. 07/621129, entitled "Clean-up Subsystem for Chemical 
Decontamination of Nuclear Reactor Primary System," and application Ser. 
No. 07/621130, entitled "Resin Processing System," all of which are 
incorporated herein by reference. 
The designing of such a system to allow for the installation of all 
equipment coming into contact with radioactive material within the 
containment chamber is necessary for certain nuclear plants. Such an 
"in-containment" configuration has several advantages over an 
"outside-of-containment" configuration. First, in the unlikely event of a 
leak in the decontamination system equipment which is exposed to the 
radioactive material, the leak remains inside of containment. Second, the 
piping may be single wall hose since it is located within the containment 
area. Third, the process piping runs can be kept to a short distance, 
therefore negating the need for a secondary envelope medium to minimize 
the risk of a leak. 
It has been found that the optimum interface between the chemical 
decontamination system and the primary reactor coolant system is via the 
residual heat removal (RHR) system. This is further detailed in a 
co-pending application Ser. No. 07/621120, entitled "System for Chemical 
Decontamination of Nuclear Reactor Primary Systems," and incorporated 
herein by reference. 
Referring to FIG. 1, a system is shown which allows for connection between 
a partially inside of containment decontamination system 30 and the RHR 
system which is also inside of containment. The containment barrier 100 
ensures that any catastrophic reactor problems will not leak radiation 
into the outside of the containment environment. 
Processed fluids from the hot leg of the primary reactor coolant system 
(RCS) of a nuclear reactor are fed to the RHR system via valve 10. Two RHR 
heat exchanger trains are shown and one such train is capable of 
maintaining the necessary cooling of the reactor during a fuel removal 
processing operation. 
The primary reactor coolant is directed through valve 12 and to the primary 
residual heat exchanger 16 for cooling the coolant during the refueling 
operation. The coolant which exits the primary residual heat exchanger 16 
flows through the primary line 52 and through the primary isolation valve 
20 to the cold leg entry of the primary reactor coolant system. 
The inventive system allows for the primary reactor coolant to be directed 
to the decontamination system 30. This is accomplished by directing the 
coolant through valve 14 and into secondary residual heat exchanger 18. 
The coolant exits from the secondary residual heat exchanger 18 and flows 
through the secondary line 50. The coolant can be directed via 
out-containment line 60 and to the high head safety injection (HHSI) pumps 
via valve 32. 
The decontamination system 30 is connected to the secondary line 50 via 
in-containment inlet valve 22 on the in-containment inlet line 54 and 
in-containment outlet valve 24 on the in-containment outlet line 56. Both 
the in-containment inlet line 54 and the in-containment outlet line 56 are 
connected to the secondary line 50 at a point upstream from the secondary 
isolation valve 28. The secondary isolation valve 28 provides separation 
of the two heat exchanger trains in conjunction with the primary isolation 
valve 20. 
The decontamination of the coolant is accomplished by directing the coolant 
through the secondary residual heat exchanger 18 and exiting through 
secondary line 50. By closing an in-containment isolation valve 26 located 
on the secondary line 50 downstream of the in-containment inlet line 54 
and upstream of the in-containment outlet line 56, the coolant is diverted 
to the decontamination system 30. After the decontamination process is 
complete, the in-containment isolation valve 26 is opened and the 
in-containment inlet valve 22 and in-containment outlet valve 24 are 
closed. 
Two lines are established between the decontamination system 30 to the 
outside of the containment area. Due to the limited space available for 
decontamination process equipment within the containment area, it is 
preferred to only house decontamination equipment which contacts 
radioactive products inside of containment. Therefore line 45 is provided 
which allows for fresh resin to be brought into the decontamination system 
30. Also, line 49 is provided which allows for fresh chemicals to be 
injected into the primary fluid. These lines 45, 49 are preferably mounted 
to enter through the containment barrier 100 via the equipment hatch 97. 
The decontamination apparatus system depicted in FIG. 1 therefore provides 
for the employment of a chemical decontamination system which is partially 
within the containment chamber. The apparatus provides for connections to 
the residual heat removal system at a point downstream of the secondary 
residual heat exchanger 18 and at a point upstream of a secondary 
isolation valve 28. The system allows for the positioning of all equipment 
used in the decontamination process which contacts the radioactive 
materials to be housed within the containment chamber. 
Certain aspects of the equipment utilized in the full system chemical 
decontamination system and the process flow connections between these 
systems are set forth in co-pending application Ser. No. 07/621129, 
entitled "Clean Up Subsystem for Chemical Decontamination of Nuclear 
Reactor Primary Systems," and application Ser. No. 07/621130, entitled 
"Resin Processing System," and both of these are incorporated herein by 
reference However, since the entire full system decontamination process is 
not disclosed in either of those two applications, the full system will be 
set forth hereinafter Certain aspects of each system and of the 
connections between each system and the workings of each system are 
disclosed within those documents and may be helpful in understanding 
certain aspects of the present invention. 
The preferred embodiment of the full system decontamination process as 
described hereinafter is sized to operate within a "four-loop" reactor. 
Such a reactor has four reactor coolant system steam generation systems. 
The same process may be employed for smaller plants utilizing "two-loop" 
and "three-loop" designs. The smaller plant designs would employ a smaller 
equipment design which would be roughly proportional to the reduction in 
wetted surface area compared to the "four-loop" design. 
Referring now to FIG. 2, process fluids from the primary system are sent 
via line 54 to an optional back-flush filter system 701. The back-flush 
filter system 701 is provided to filter suspended solids found in the 
primary system which are removed from the primary system during the 
decontamination. This system is provided to remove manganese dioxide 
colloids or other particles which may be generated during the known 
CAN-DEREM and LOMI techniques. Certain chemical decontamination processes 
may not generate suspended solids in the primary process fluids. 
Therefore, the utilization of the back-flash filter system 701 is 
considered to be optional and not a necessary element of the inventive 
process. 
In the embodiment of the invention as shown in FIG. 2, the process fluids 
first enter a back-flush filter 301. This back-flush filter 301 can be 
periodically back-flushed by use of accumulator 300 which has an inlet 
nitrogen line 40 connected thereto. Also, line 41 provides demineralized 
water to aid in the back-flushing of the back-flush filter 301. When a 
back-flush step is in process the back-flushed material will be collected 
into filtrate collection tank 101 and can be pumped via filtrate transfer 
pump 201 along line 42 to any of the spent resin storage tanks 121, 122, 
123, 124, 125, 126, 127, 128 shown on FIG. 5. After exiting the back-flush 
filter 301 the process fluids enter optional post filters 302, 303, 304 
305. 
The back-flush filter 301 is preferably sized to handle the entire flow 
rate of the decontamination process, in this case 1500 gallons per minute 
(gpm), and has a 5-20 micron filter. The accumulator 300 is preferably 
sized to have a capacity sufficient to perform a complete backflush, in 
this case 30 gallons. The filtrate collection tank 101 is sized to have a 
capacity of several backflush volumes, and preferably about 400 gallons. 
The filtrate collection pump 201 is preferably sized to empty the filtrate 
collection tank 101 in less than an hour with a capacity of 10-50 gmp. The 
post filters 302, 303, 304, and 305 are designed to operate in parallel 
and preferably have a combined flow rate equal to the back-flush filter 
301, and preferably having a capacity of about 375 gpm individually, and 
having about a 1 micron filter rating. Any type of filtering equipment may 
be used to constitute the back-flush filter system 701. Other embodiments 
may include the use of cartridge filters with or without a preliminary 
back-flush filter. 
After exiting the post filters 302, 303, 304, 305, the process fluid 
travels through line 43, and now referring to FIG. 3, enters the 
demineralizer system 702. The demineralizer system 702 is provided to 
remove up to 99% of the chemicals which are added during the chemical 
decontamination process. This system is shown as being comprised of 
demineralizers 80, 81, and 82. Preferably, at least two demineralizers are 
employed, however, more than two demineralizers may be used. In the 
preferred embodiment, demineralizer 82 is a Regen demineralizer and has a 
total volume of about 400 ft..sup.3 (11.3 m.sup.3). Most preferably this 
Regen demineralizer contains three demineralizer vessels 611, 612, and 613 
which each have a volume of about 133 ft..sup.3 (3.8 m.sup.3 ). In the 
preferred embodiment two other demineralizers 80, 81 are also employed and 
each contain three demineralizer vessels 621, 622, 623, 631, 632, 633 
which each have a volume of about 200 ft..sup.3 (5.7 m.sup.3). The amount 
of ion exchange resin used for decontamination is determined by the amount 
of deposits which have been produced in the RCS system. A small amount of 
deposits in a RCS would require less resin than that required for a 
heavily contaminated RCS facility. 
The demineralizers 80, 81, 82 are flow coupled to line 45 which is used to 
supply fresh resin to the demineralizer system 702. Line 70 is also 
provided for the introduction of sluice water to the demineralizer system 
702 in a counter flow fashion to be used to flush spent resin out of the 
demineralizer vessels. The spent resin exits the demineralizer system 702 
via line 71. The process fluid can also be diverted around the 
demineralizer system 702 via line 48. 
After the process fluids exit the demineralizer system 702 they are 
transported via line 44 to the resin fines filter system 703. The resin 
fines filter system 703 is provided to ensure that any resin from the 
demineralizer system 702 does not enter the primary system. The resin 
fines filter system 703 preferably contains a plurality of filters which 
have a combined total flow rate capacity equal to the decontamination 
system flow rate of about 1,500 gallons per minute. In the preferred 
embodiment, four resin fines filters 306, 307, 308, 309 are utilized. Each 
resin fines filter 306, 307, 308, 309 has a capacity of about 375 gallons 
per minute and a filter rating of about 25 micron. 
After exiting the resin fines filter system 703 the process fluid is 
transported via line 47, and referring to FIG. 4, back to the primary 
system via line 56. 
Prior to the entry back into the primary system, chemicals are injected 
into the processed fluids. In the preferred embodiment, two chemical 
injection systems are utilized. First is a vanadous formate system 704. 
This vanadous formate system 704, in the preferred embodiment, has a 
vanadous formate tank 131 which contains the vanadous formate compounds in 
solution. The vanadous formate solution is preferably prepared by use of a 
recirculation and heater system shown in a preferred embodiment as a 
vanadous formate mixing pump 206 flow coupled to a vanadous formate heater 
91. When the vanadous formate solution is ready to be injected into the 
process fluids, the vanadous formate injection pumps 207, 208 are 
activated. This vanadous formate system 704 is utilized when a LOMI 
decontamination process is required by the decontamination process. 
The second chemical injection system is the chemical system 708 which is 
shown in the preferred embodiment as comprising a chemical mixing tank 132 
which also has a recirculation and heater system shown in the preferred 
embodiment as chemical mixing pump 209 and chemical heater 92 for 
dissolving decontamination chemicals in solution. This system is capable 
of supplying those chemicals used in the decontamination process. When 
chemicals from the chemical mixing tank 132 are ready to be sent to the 
process, the chemical injection pumps 210 and 211 are activated. This 
chemical system 708 is preferably designed to handle those chemicals 
utilized in a CAN-DEREM process as required by the decontamination 
process. 
In the preferred embodiment, both the vanadous formate 131 and the chemical 
mixing tank 132 are about 3000 gallons in size and both preferably contain 
an agitator. The amount of decontamination chemicals which must be 
injected is dependent upon the amount of deposits in the RCS. The vanadous 
formate mixing pump 206 and the chemical mixing pump 209 are both 
preferably sized for a flow rate of about 100 gallons per minute. The 
vanadous formate injection pumps 207, 208 and the chemical injection pumps 
210, 211 are preferably sized for a flow rate of 50 gallons per minute. 
The chemical injection system is flow coupled to the line 47 via line 49 
for injection of the chemicals into the processed deionized and filtered 
fluids prior to reentry of those fluids into the primary system via line 
56. 
Referring now to FIG. 5, the new resin system 707, the spent resin storage 
system 705, the sluice water system 706, and the decontamination waste 
system 709 are shown. When the ion exchange resin is spent, the 
demineralizer system 702 has to be regenerated with new resin. The sluice 
water system 706 is employed to remove the spent resin. Sluice water is 
provided from the sluice water supply tank 113 to the demineralizer system 
via line 70. The sluice water travels through the sluice water pump 204 
and the sluice water filter 310 prior to entering the demineralizer system 
702. 
The sluice water system 706 also contains a sluice water recycle pump 205 
for recycling the sluice water from the demineralizer system 702. The 
amount of sluice water required for transport of the resin is dependent 
upon the amount of resin to be removed. The sluice water supply tank is 
preferably sized to have a capacity of 1,800 gallons of sluice water. The 
sluice water filter 310 is preferably sized to have a capacity of 100 
gallons per minute and the sluice water pump 204 and the sluice recycle 
pump 205 are preferably designed to have a capacity of about 100 gallons 
per minute flow rates. 
After the sluice water enters the demineralizers via line 70, the sluice 
water carries the spent resin from the demineralizer system via line 71 to 
the spent resin storage system 705. The spent resin storage system 705 is 
comprised of a series of tanks which preferably have a combined total 
storage volume of about 34,400 gallons. In the preferred embodiment, eight 
spent resin storage tanks 121, 122, 123, 124, 125, 126, 127, 128 are 
provided with each having a capacity of about 4,300 gallons. These tanks 
are provided with screen bottoms such that the sluice water exits these 
tanks and is recirculated via the sluice water recirculation pump 205 to 
the sluice water supply tank 113. Line 42, from the filtrate collection 
tank 101 is connected to line 71 upstream of the spent resin storage tank 
system 705. 
A new resin system 707 is preferably included in a decontamination process 
overall system in order to batch fresh resin to the demineralizer system 
702. The new resin system 707 is preferably comprised of a resin supply 
tank 112 which contains fresh resin. This tank is flow coupled to line 66 
which carries demineralizer water from demineralizer water source 65. The 
solution of resin and demineralizer water is sent to the resin batching 
tank 111 by the resin supply pump 203. A quantity of resin to fill a 
demineralizer vessel 611, 612, 613, 621, 622, 623, 631, 632, 633 is then 
transported from the resin batching tank 111 by the resin feed pump 202 
via line 45. 
In the preferred embodiment, the resin supply tank 112 is capable of 
storing about 7000 gallons of resin. The resin batching tank 111 is 
preferably sized to hold about 2100 gallons of solution. The resin feed 
pump 202 and the resin supply pump 203 are both preferably sized to have a 
capacity of about 100 gpm. 
A decontamination waste system 709 is also provided. This decontamination 
waste system 709 comprises a decontamination waste tank 133 which 
preferably has a volume capacity of about 3000 gallons. The 
decontamination waste tank 133 is flow coupled to line 70. A 
decontamination waste pump 212 is flow coupled to the decontamination 
waste tank 133 for pumping the decontamination waste via line 73 to a 
storage system. The decontamination system 709 is designed to collect 
waste solutions from any of the group consisting of the back-flush filter 
system 701, the demineralizer system 702, the spent resin storage tank 
705, and the sluice water system 706. 
After the full system decontamination process was developed, the task of 
employing such a system inside the containment chamber had to be met. 
Various design problems exist such as (1) ensuring that all of the 
equipment which contacts radioactive materials is placed inside of the 
containment; (2) locating the equipment so that it fits within the 
containment while minimizing the total length of piping between each 
system; (3) ensuring proper shielding of the equipment for personnel 
protection; (4) limiting the restrictions on the polar crane movement by 
the necessary piping and (5) providing for easy installment and removal of 
the processing equipment Since this inventive layout of the full 
decontamination process is likely to be employed in currently existing 
reactor facilities, the amount of available area in the containment 
chamber is relatively small and fixed. 
The design layout configuration of the present invention provides for 
supplying the equipment necessary for the full system decontamination 
process in divisible units. These units are placed upon skids which can 
fit through the equipment hatch of the containment chamber. Since this 
hatch has a diameter of about fifteen feet, skids having a maximizing 
height of twelve feet and a maximum width of ten feet were chosen for 
transporting the equipment. The use of individual skids also has the 
benefit of permitting the units to be pre-assembled at the factory, 
therefore not requiring certain assembly and testing at the installation 
site. These skids are also designed for easy transportation to a 
particular nuclear facility without the need for special transportation 
permits. Another key design feature was to design each system so that it 
could fit upon an individual skid, or a plurality of skids which would be 
situated in close proximity to one another. The design factor of available 
space in the containment area sometimes conflicts with such a skid design. 
The chemical decontamination process on a full scale basis may only be 
needed two to three times per reactor life. It may therefore be desirable 
to remove the equipment when not in use. Therefore, a modular design was 
required which would lend itself to easy equipment set-up and removal. 
Referring now to FIG. 6, a preferred in-containment layout design is shown 
in a typical four-loop pressurized water nuclear reactor. In this layout 
design, skid positions were established for various systems comprising the 
decontamination system. Due to the extreme space requirements imposed upon 
such an in-containment design layout, the positioning of all equipment 
which would not come in contact with radioactive materials is directly 
outside of the containment chamber. It is preferred that these outside of 
containment systems be as close to the equipment hatch 97 as possible to 
minimize piping length. The fluid and material connections between these 
outside of containment process units and those process units contained 
inside of the containment chamber 99 is made via the equipment hatch 97. 
The systems which are kept outside of the containment chamber 99 are the 
vanadous formate system 704, the chemical system 708, and the new resin 
system 707. In the preferred embodiment, the vanadous formate system 704 
is positioned on a vanadous formate skid 513 directly outside of the 
equipment hatch 97. The units comprising the vanadous formate system 704 
are positioned on the vanadous formate skid 513 which preferably covers an 
area of about 120 ft..sup.3 (11.2 m.sup.2). 
Directly beside the vanadous formate skid 513 is the chemical injection 
skid 514. This chemical skid 514 comprises the chemical system 708. The 
chemical skid 514 preferably covers an area of about 120 ft..sup.2 (11.2 
m.sup.2). 
The new resin system 707 is also located outside of containment and is 
located on the new resin system skid 505. The new resin system skid 505 
preferably covers an area of about 230 ft..sup.2 (21.4 m.sup.2). 
The rest of the full containment decontamination system is housed inside of 
the containment barrier 100. A major difficulty in sizing the processing 
equipment and in locating the processing equipment was the lack of free 
space available and also in trying to avoid disturbing the path taken by 
the polar crane inside the containment chamber 99. The crane path is shown 
by the inside crane track 95 and the outside crane track 96 which form 
circles inside the containment chamber 99. The crane tracks 95, 96 
therefore dissect the operating floor 98 into two distinct regions within 
the containment chamber 99, and create an outer operating floor annulus 
94, defined by the space between the containment barrier 100 and the 
outside crane track 96. 
An important design criteria was to minimize the amount of piping necessary 
to connect the different systems within the entire chemical 
decontamination process. In order to accomplish this, the demineralizer 
system 702 was divided into integral parts consisting of three 
demineralizer vessels per demineralizer skid. Due to the relatively large 
area required by the demineralizer system 702, the demineralizer system 
702 was placed along the outer operating floor annulus 94. As shown in the 
preferred embodiment in FIG. 6, the demineralizer system 702 was located 
upon three skids, demineralizer system--A skid 506, demineralizer 
system--B skid 507 and demineralizer system--C skid 508. The demineralizer 
skid--A 506 contains demineralizer vessels 611, 612 and 613. This 
demineralizer system--A skid 506 covers an area of about 160 ft..sup.2 
(14.9 m.sup.2). The most preferred skid dimensions for the demineralizer 
system--A skid 506 are 8 ft. (2.4 m.) wide by 20 ft.(6.1 m.) long and less 
than 12 ft. (3.7 m.) high. 
In close proximity to the demineralizer system--A skid 506 is placed the 
demineralizer system--B skid 507 which is preferably located as close to 
the demineralizer system--A skid 506 as is possible on the outer operating 
floor annulus 94. Directly beside the demineralizer system--B skid 507 is 
the demineralizer system--C skid 508. Both the demineralizer system--B 
skid 507 and demineralizer system--C skid 508 contain the demineralizer 
vessels 621, 622, 623, 631, 632, and 633. The six vessels are all equally 
sized and each contain a volume of approximately 200 ft..sup.3 (5.7 
m.sup.3) and are split three vessels per skid. By arranging the 
demineralizer system 702 on these three skids in a close proximity to one 
another, the length of piping between the three skids is minimized. This 
is a preferred aspect of the in-containment design layout due to the 
necessity for various piping systems to be connected to the demineralizer 
system 702. 
In the preferred embodiment, single wall hose (flexible hose) is employed 
as the piping material. This type of piping has a lined inside and a 
corrugated metal tube outside. Such piping provides for flexibility in the 
piping system as opposed to standard piping which is stationary. 
The demineralizer system--B and--C skids 507, 508 both comprise an area of 
approximately 160 ft..sup.2 (14.9 m.sup.2), and most preferably have an 8 
ft. (2.4 m.) width and a length of 20 ft. (6.1 m.) with a height of less 
than 12 ft. (3.7 m.). The distance between these skids is to be minimized. 
Preferably, the distance between each demineralizer skid--A,--B, and--C, 
506, 507, 508 is less than 50 ft. (15.3 m). Most preferably the distance 
between these skids is less than 20 ft. (6.1 m.), however, due to existing 
equipment on the outer operating floor annulus 94 the skids may not be 
able to be placed in a side-by-side manner. 
Due to the piping which must connect the demineralizer system 702 with the 
spent resin storage system 705, these two systems are preferably located 
as close to each other as possible. However, since a vast portion of the 
operating floor 98 to the inside of the inside crane track 95 is occupied 
by equipment comprising the nuclear reactor and its steam plant, (such as 
the steam generators 88) the outer operating floor annulus 94 is utilized 
to house most of the spent resin storage tank system 705. In the preferred 
embodiment disclosed in FIG. 6, the spent resin storage system 705 is 
shown as comprising eight separate spent resin storage tanks 121, 122, 
123, 124, 125, 126, 127, and 128. Each spent resin storage tank is 
preferably sized to contain about 4,300 gallons of solution. These tanks 
are preferably of a noncylindrical shape to save space and increase fluid 
volume per unit area of floor space. 
Spent resin storage system--A skid 509, spent resin storage system--B skid 
510, spent resin storage system--C skid 511 are placed on the outer 
operating floor annulus 94 in the preferred embodiment shown in FIG. 6. 
Each of these skids contains two of the spent resin storage tanks. Due to 
the limited space available in the outer operating floor annulus 94 in 
most nuclear reactors, a few of the spent resin storage tanks may have to 
be located elsewhere on the operating floor 98. Since, for space saving 
reasons, two resin storage tanks are outfitted onto each skid system, the 
preferred design shown in FIG. 6 shows a spent resin storage system--D 
skid 512 on the operating floor 98. The spent resin storage tank skids are 
preferably equally sized for efficiency and interchangeability with the 
overall decontamination process. The preferred size of the spent resin 
storage system--A, B, C, D skids 509, 510, 511, 512 is 8 ft. (2.4 m.) wide 
and 20 ft. (6.1 m.) in length for a preferred area of about 160 ft..sup.2 
(11.2 m.sup.2). These skids are also less than 12 ft. (3.7 m.) in height. 
The decontamination waste system 709 is also housed within the containment 
chamber 99. This system is preferably placed on the outer operating floor 
annulus 94 beside one of the spent resin storage system skids, namely 
spent resin storage system--C skid 511. The decontamination waste system 
skid 503 is preferably about 80 ft..sup.2 (7.4 m.sup.2) in area and most 
preferably is 10 ft. (3.0 m.) in width and 8 ft. (2.4 m.) in length and a 
height of less than 12 ft. (3.7 m.). 
Due to the scarcity of available space on the outer operating floor annulus 
94, other decontamination process systems are placed on the operating 
floor 98. The back-flush filter system 701 is placed on a back-flush 
filter system skid 501 located on the operating floor 98. This skid is 
preferably about 120 ft..sup.2 (11.2 m.sup.2) in area and most preferably 
12 ft. (3.7 m.) in width and 10 ft. (3.0 m.) in length. This back-flush 
filter system skid 501 is located in close proximity to the demineralizer 
system 702 since these two systems are flow coupled together. The resin 
fines filter system 703 is contained on the resin fines filter systems 
skid 502 which is placed on the operating floor 98. This resin fines 
filter system skid 502 preferably covers an area of approximately 30 
ft..sup.2 (2.8 m.sup.2) and is most preferably 10 ft. (3.0 m.) in width 
and 3 ft. (0.9 m.) in length and a height of less than 12 ft. (3.7 m.). 
The last system to be placed in the containment chamber 99 and on the 
operating floor 98 is the sluice water system 706 which is placed on a 
sluice system skid 504. This skid preferably covers an area of about 120 
ft..sup.2 (11.2 m.sup.2) and most preferably is 12 ft. (3.7 m.) in width 
and 10 ft. (3.0 m.) in length and a height of less than 12 ft. (3.7 m.). 
All of the system skids which are housed within the containment chamber 99 
require maximum shielding protection. This maximum shielding protection 
can be accomplished by various shielding walls. A preferred shielding wall 
is a 8 inch (20.3 cm.) to 24 inch (61.0 cm.) solid block wall made of 
concrete and most preferably concrete containing a lead additive. The 
shielding wall is shown in FIG. 6 as shield 93. 
The preferred design for an in-containment chemical decontamination process 
is set forth in which all of the processing systems which handle 
radioactive material are located within the containment chamber of the 
nuclear reactor. The design employs the use of individual skid systems 
which allow for flexibility in equipment layout and the use of flexible 
single wall hose for flexibility in piping interconnections. The system is 
ideally constructed to allow for removal of the decontamination equipment 
when the equipment is not in use.