ML20214X096
| ML20214X096 | |
| Person / Time | |
|---|---|
| Site: | Framatome ANP Richland |
| Issue date: | 05/31/1987 |
| From: | SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER |
| To: | |
| Shared Package | |
| ML20214X045 | List: |
| References | |
| NUDOCS 8706160327 | |
| Download: ML20214X096 (17) | |
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ACVANCED NUCLEAR FUELS CORPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART I - LICENSE CONDITIONS REV.
6.5 UFg Cylinders New UF6 cylinders purchased by ANF shall conform to ANSI N14.1 which includes certification by the vendor that the cylinders comply with all fabrication, test and cleanliness requirements specified therein. Periodic inspection and testing of cylinders is performed following heel removal.
The heel removal procedures specifically exclude the use of hydrocarbons.
Cylinders of UF6 are received, unloaded and stored on a barricaded pad.
As needel for processing, cylinders of UF6 are transferred to either on elevated dock or a barricaded pod adjacent to the UO2 Building.
UF6 cylinders are stored bare in cradles providing spacing and stability.
The cylinder valve seals which were installed by the shipper are left intact until the cylinder is moved into the plant for emptying.
Evacuated UF6 cylinders (containing heels) are also stored in these Iccations.
Elevated or barricaded storage of bare UF6 cylinders is designed to guard the c.ylinders against vehicular damage.
Pr ior to shipping bare cylinders containing heels, the valves are covered and realed. When the cylinders are shipped in overpacks, the valves are not covei ed on ! sealed but the overpacl: is sealed.
8706160327 870521 h
PDR ADOCK 07001257 C
PM APAEtJDtJEtJT APPLICATIOtJ DATE:
P AGE PJO.;
Mov 1987
.. t XNM F01422 (2/87)
s ADifANCHD NUCLEAR FUEL 3 CORPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRATION s gy, CHAPTER 15 PROCESS DESCRIPTION AND SAFETY ANALYSIS in the uranium oxide fuel manufacturing process described below, a number of techniques are employed throughout the plant to assure criticality safety. These include:
The use of safe geometry, i.e., critically safe slabs and cylinders placed in arrays that limit interaction by separation; Limitations on the form and fissile content of the fuel being processed such as the 5 wt% U-235 limits in the UO2 and Specialty Fuels Building; The use of mass control where a uranium processing vessel or container is limited to a safe batch not exceeding 45% of the minimum critical mass:
Control of moderators as exemplified by the large batch uranium oxide blenders; and The use of neutron absorbers as in the case of the bundle storage array which utilizes Boral as a neutron absorber.
Any process or equipment which handles uranium in any form is carefully reviewed prior to startup to determine that the double contingency princiole is me t.
Each review is then independently evaluated and periodic audits are conducted to determine that the equipment is materially unaltered, that practices are compatible with original operating assumptions, and that procedures are adhered to.
15.1 Reactions of Hydrocarbons with UF3 The reactions of hydrocarbons with UF, even in small quantities, can be 6
vigorous to the point of serious explosions. Therefore, ANF has assessed its controls to prevent the introduction of hydrocarbons into cylinders or UF6 systems and find thern adequate. These various controls are outlined below.
The purchase specihcotion of new 30B cylinders require conformance to ANSI N14.1 which includes certification by the vendor that cleanliness requirements specified therein have been met.
Recertification and main-tenance on cylinders is also performed within the requirements of ANSI N!4.l.
The procedures for cylinder heel removal and washinq ;)rior to maintenance or recertification specifically exclude the ose of hvdrocarbons.
The equipment used for processing liF,; is desianed to exclode the need for hydrocarbons (oil).
For example, the vocoom pomp used to reduce cylinder heels is a diaphragm vacoom pump rather than on nil filled pomo.
AMENDP. TENT APPLIC ATION DATE:
P AGE tJO.:
May I987 l5-I XN AF.F01422 (2187)
/
s ADVAE.*C D NUCL2AR FUEL 3 CCRPORhTION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET No. 70-1257 PART 11 - SAFETY DEMONSTRATION REV.
An Engineering Change Notice (ECN) must be authorized to modify equipment which requires review and approval in accordance with Figure 1-2.2 and would therefore protect against hydrocarbons being utilized in the future.
15.2 Conversion of UFg to UO7 Goseous UF6 may be converted to uranium oxide through either of two processing routes: a wet "ADU" process, or a dry conversion p.ocess.
In the former process, UF6 is first contacted with water to form uranyl fluoride (UO F ), reacted with ammonium hydroxide (NH 0H) to produce ammonium 22 4
diuranate (ADU) crystals, centrifuged and dried to remove liquids, and finally calcined in an hydrogen-nitrogen-steam atmosphere to convert the ADU solids to uranium oxide.
The dry conversion process route contrasts significantly from the ADU route in that UF6 is reacted directly with hydrogen-nitrc. gen-steam atmosphere and calcined to form ceramic grade uranium oxide.
In both conversion processes, emphasis is placed on control and contain-ment of the uranium-bearing materials, and on the industrial safety aspects of handling highly corrosive chemicals. A process of f-gas system is provided to treat fumes from the process, ventilated hoods are utilized around process equipment to control airborne uranium contamination. and the air in the chemical processing areas is changed out at frequent intervals by a once-through ventilation system.
15.2.1 Receipt and Storage of UFg Cylinders Uranium feedstock enters the plant by truck in the form of uranium hexafluoride (UF ), normally contained in Model 30 cylinders shipped in steel 6
overpacks. Smaller cylinders may by used where quantities or enrichment dictate.
Cylinders are unloaded by crane, weighed and stored in a safe array on a covered pad.
The cylinder valve seals which were installed by the shipper are lef t intact until the cylinder is moved into the plant for emptying.
To assure criticality safety in conversion and subsequent processing, each numbered cylinder is checked for U-235 content using a gamma counter to verify the shipper's values. For cylinders containing greater than 4.5 wt%
U-235, a UF6 sample generated at the point where the cylinder is filled is analyzed using mass spectroscopy in the Exxon Nuclear laboratory.
15.2.2 Vaporization A f ter verification of enrichment, serial number. and cylinder weicht to preclude heating on overfilled cylinder, l>F ; cylinders are moved by forklif t t
and overhead monorail hoist to the vapori/ation f acilities of the I f(b Building.
Once in the vapori/ation areas, ventilated to be the most negntive /one of AMErJOMEf4T APPLICATICfd DATE:
PAGE rJO.:
May 1987 15-2 xrimot422 man
/
s ADVANCEDNUCLEARFUELSCORPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRATION REV.
the building, a cold volve check is performed to evaluate the condition of the cylinder valve. If the cylinder is not found to be under negative pressure, it is evacuated and the volve is checked for leakage. A replacement volve is installed if a leak is indicated.
UF6 cylinders are then placed in electri-cally-heated, ventilated chests where they are connected to a welded, heated, and insulated stainless and monel header system used to transport UF6 gas to the hydrolysis tank.' A backup safety shutof f valve is installed next to the cylinder valve for added protection against uncontrolled release of gas from the cylinder. Prior to heatup of the cylinder, the header system is pressure-tested with dry nitrogen to check for leaks.
The vaporization chests, each limited to a single cylinder, are maintained slightly negative with respect to the surrounding room to contain any UF6 leakage within the chest. Also, an emergency scrubber system is connected to the vaporization chests by ventilation ducting. The emergency system may be activated by emergency push buttons, mounted at the area exits, and alternatively from the conversion area control rooms located on the floor above the vaporization areas.
Activation of the emergency scrubber system causes the UF6 vapor to be drawn into the scrubber, converted to uranyl fluoride by contact with water, and stored in critically safe tankage as uranyl fluoride (UO F ) solu-22 tion. This solution may then be processed via the standard ADU route.
This safety system is tested at routine intervals to verify operability.
UF6. cylinder temperature and pressure are carefully monitored and recorded during heatup and vaporization.
In addition to separate control thermocouples, thermocouples are mounted on the skin of the UF6 cylinder which activate a shunt trip breaker to shutdown chest heater power in case of an over-temperature condition.
A separate backup infrared temperature sensing system also activates the shunt trip breakers to prevent cylinder overheating. Burnout of a thermocouple causes the control instrumentation to drive up-scale and safely shutdown cylinder heating.
As indicated above, the weight of each UF6 cylinder is confirmed upon cylinder receipt to preclude rupture of an overfilled cylinder during the solid-to-liquid phase change and subsequent volume expansion which occurs during cylinder heating.
Personnel connecting and disconnecting UF6 cylinders are required to use protective clothing including coveralls, rubber shoe coverings and plastic gloves.
It is also a requirement that a full f ace mosk, connected to an emergency breathing air supply, be worn when connecting and disconnecting cylinders.
Separate celf-contained breathing equipment and acid suits are available in case of emergency.
AMENDMENT APPLICATION DATE:
PAGE NO.:
May 1987 15-3 XN-NF.F01822 (2/87)
/
w AD1fANCED NUCLEAR FUELS CCRPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRATION REV.
Safety protection for eyes is required at all times throughout the chemical areas.
15.2.3 Hydrolysis and Precipitation In the wet route process, the UF6 gas is contacted with water in on eductor nozzle and the resultant UO F2 2 solution is collected in safe geometry cylindrical tanks.
The UF6 cylinders, which utilize moderation control as a criticality safety feature, are protected against accidental internal flooding from the hydrolysis system by a pressure control interlock system. A UF6 flow control valve located between the hydrolysis tank and the UF6 cylinder is automatically closed if the pressure in the UF6 header drops to o preset pressure above the hydrolysis water supply pressure. This positive differential-pressure protects against the flow of water or uranyl fluoride into the header piping and cylinder. Periodic tests are performed on this safety system to demonstrate its operability. A ventilated containment hood is provided over each hydrolysis tank to protect against small UF6 g s leaks.
The uranyl fluoride produced in the hydrolysis system is mixed with ammonium hydroxide to produce ammonium diuranate precipitate (ADU). The precipitation tanks are critically safe by virtue of geometry and are vented to the procer.s of fgas system to prevent release of ammonio vapors to the operating arco. Housekeeping is enforced to eliminate uranium solution spills which might dry and result in airborne contaminntion and safety showers are provided at strategic locations in the chemical area in case of operator contact with acid or caustic solutions.
15.2.4 Centrifugation Drying and Calcination Continuous centrifuges are used to separate solid ADU from the liquid stream.
The solids are dried in a ventilated, oil-heated dryer, and the ammoaia and water vapors are removed from the offgas stream by scrubbing in the process offgas system (POG). The high temperature silicone oil, used in the dryer as a heat exchange medium, is stable and not flammable at the ADU dryer operating temperatures. Dryer temperatures are automatically controlled and provision is made to protect against overheating of the oil by electrical shutdown of the oil heating system.
Dry ADU is fed from the dryer into o calciner through on enclosed feed chute to produce o dry uranium oxide product.
Both ends of the rotating tube continuous calciner are vented by hoods attached to the calciner throuqt rotating seals.
The of fgas from the calciner, which contains particulate uranium as well as fluorides, hydrogen, nitrogen and steam. is discharged through a liquid scrubber and is HEPA filtered alona with the air from the calciner seal hoods.
AMENDMENT APPLICATION DATE:
P AGE NO.:
tAoy I"87 15-4 XNWF-FO1422 (2/87)
L
O ACJAVCED NUCLEARFUELSCCRPORhTION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRATION REV.
The calciner, which operates at a slight negative pressure, is protected from the possibility of a hydrogen explosion by operation above the auto-ignition temperature of the gas, Nitrogen-purged rotary airlocks are used to discharge uranium oxide from the calciner and to control in-leakage of air.
15.2.5 Dry Conversion The dry conversion process contacts a mixture of steam, nitrogen and hydrogen with vaporized UF6 to form dry uranium oxide powder.
The offgas stream antaining excess steam, hydrogen, nitrogen and HF is treated by condensing and neutralizing the acid, scrubbing the noncondensible via the chemical area process offgas system scrubber, and then being exhausted through HEPA filters. This process is considered proprietary and is discussed, along with appropriate safety features, in documents referenced in Chapter 6.
15.2.6 Waste Handling E f fluent from the ADU centrifugation is treated by further processing through polishing centrifuges or filters followed by contact with an ion exchange resin bed before discharge from the UO2 Building through a uranium sampler to the waste storage lagoon system.
Criticality safety of the ion exchance columns is assured through use of a neutron absorber column in the center of each column.
The B C obsorber is inspected periodically to 4
determine its condition and distribution.
15.3 Uranium Oxide Powder Following the calcination operation, UO2 powder is processed through a series of steps to enhance its sintering and pressing characteristics.
These process steps, collectively termed " Powder Preparation", include blending, milling, compaction and granulation.
Since uranium oxide at any of these steps contains varying quantities of finely divided particles, care is taken in the processing and handling to provide containment.
Containment is achieved through use of sealed equipment and through use of hoods and enclosures surrounding the equipment, where appropriate, which are connected to the exhaust ventilation system.
The ventilation system is sized and designed to provide airflows through hood openings of 125 linear feet per minute or greater, and the air removed from the hoods is passed through HEPA filters prior to entering the main exhaust ductwork.
Dampers are provided in the ducting to control the flow of exhaust air and to compensate for increased particulate loading in the HEPA and prefilters.
Self-odiosting dampers are also incorporated in enclosure designs which allow continuous movement of air through these containment structures even with all doors and access openings closed. Hoods and enclosures are constructed of steel, aluminum, and impact-resistant, clear plastic to allow monitoring the process, where required, without opening the containmont.
AMENDMEf4T APPLICATIOt4 DATE:
P AGE NO.:
May 1987 15-5 X N.NF.F01822 (2/87)
J
t ADVANCEDNUCLEARFUELSCORPORATION XN-2
- SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRATION REV.
Also, uranium oxide powder is transported, processed and stored in sealed, dust-tight, rnetal containers which prevent release of airborne contami-nation and ingress of moisture and contaminants. Each container is identified by serial number and by content. The location and disposition of containers is carefully controlled to prevent inaJvertent mixing in the process. Containers are generally of two types: 5-gallon pails which are limited to o single safe batch (45% of the minimum critical quantity), and 45-gallon drums which are used only for unmoderated materials and which contain a multi-pin neutron absorber structure to preclude any criticality incident.
The powder preparation operations are performed in controlled areas which are maintained negative to other operating areas and to the outside atmosphere.
Personnel are required to wear protective clothing, including rubber shoe coverings, plastic gloves, coveralls, and eye protection while operating or maintaining the equipment. Special non-routine circumstances may require limited use of respiratory protection as well.
In addition, the surf aces of equipment and floors are checked at frequent intervals to monitor for buildup of contamination.
Continuous air samplers are positioned at various locations around the equipment to detect airborne contamination.
Hand, foot, and clothing surveys are conducted on exit f rom the uranium handling arecs.
15.3.1 Powder Transport and Blending Uranium oxide discharged from the calciners is transported to one of a series of critically safe (by geometry) slab hoppers vio a negative pressure pneumatic transport system.
The material is isolated in these slab hoppers located in a designated moderated-material exclusion area until laboratory moisture analyses of representative powder samples indicate that the powder contains less than 10,000 ppm moisture. This material can then be handled as unmoderated or " dry" powder, and the hopper discharge isolation volves, which are under lock and key, are administratively released by supervisory personnel.
The dry powder may be transported to o large batch blender, again located in a moderator-exclusion arco by negative pressure pneumatic convey-ing or by gravity discharge.
Sources of moderation, such as hydrogenous lubricants, mop water, overhead liquid lines, and sprinkler systems, are excluded or strictly controlled in the area around the blenders.
15.3.2 Milling, Slugging and Granulation Following the blending step, the powder is again pneumatically t rans-ported vio a negative pressure conveying system to o hommermill feed hopper.
Unmoderated powder is processed through an enclosed. ventilated hammer-mill-powder compactor and rotary screen granulator usinq o qrovity cuscade AMENDMENT APPLIC ATION DATE:
P AGE NO.:
XN A F-FO1-822 (2/87)
J
ADVANCEDNUCLEARFUELSCORPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART ll - SAFETY DEMONSTRATION REV.
feed. The discharged powder, dry by virtue of its having entered the modera-tion-controlled preparation system at less than 10,000 ppm moisture, is then placed in 5-gallon poils er 45-gallon drums and transported to the powder storage facility.
15.3.3 Powder Storage The powder storage facility contains on array of metal storage shelving designed to meet requirements of seismic zone 11 and is operated as a moderation-controlled area. Only uranium oxide analyzed as less than 10,000 ppm moisture or having a process source which excludes carryover of mois-ture, such as the high temperature scrap oxidation process, is stored in this facility. All process liquid lines are excluded from the area, and the building construction is such that flooding can occur only if the entire site floods.
The containers are handled and stored on metal pollets in a fixed geometric array with a minimum of 15-inch vertical separation between containers.
15.4 Pelletizing The prepared uranium powder is pressed into pellets, and sintered in high temperature hydrogen furnaces. These operations are followed by grinding outside diameters, pellet inspection and storage. The pelletizing operation is performed in a controlled area marked by limited access.
This area is operated at a pressure slightly below atmospheric to preclude egress of airborne contamination, and extensive use is made of enclosures and hooding around process equipment to contain uranium oxide contamination. As described above, crea personnel are required to wear protective clothing and eye protection while operating the equipment.
15.4.1 Lubricant Blending Powder drums are moved by electric cart from the powder storage facility to the !ube blending area. Here, the drums are placed in ventilated enclosures and the lids removed.
Weighed quantities of lubricant and, as required, poreformer are added to each container.
A special drum lid is fitted to each drum and the sealed container is loaded into a tumble mixer.
Following blending, the container is marked to show the qucntity of lubricant added.
The equivalent moisture content, including hydrogen contained in the lubricant and poreformer, remains below the 10,000 ppm level required for unmoderated powder.
A conical adaptor, equipped with both volve and moisture-tight cover, is fitted to each drum inside an enclosure and the sealed container is moved to the pelletiring floor for pressing.
A!iENOMENT APPLICATION DATE:
P AGE NO.:
Mny 1987 i S-7 XNWF-F01822 (2/87) t a
ADVANCEDNUCLEARFUELS CORPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRATION REV.
15.4.2 Pellet Pressing As in the case of the lubricant blend area, the area surrounding the pellet presses is designated as a moderation-controlled zone.
Overhead process liquid lines are isolated from the press area by sheet metal trays, and mop water, lubricants, and other hydrogen sources are strictly limited.
The drums are hoisted above the presses and a dust-tight connection is made between the drum and the flexible feed hose used to convey powder to the press feed hopper below. The upper portion of each press, as well as the feed hoppers, are enclosed in an exhaust hood providing protection for the press operator from airborne uranium oxide dust.
Peliets are discharged from the presses on enclosed metal conveyors and placed in refractory metal sintering boats using automatic boat loaders.
These boats which are 3.6 inches in height for criticality control purposes are moved via roller conveyors to boat storage tables. The slab geometry and 15-inch vertical separation of the boat storage array provides the necessary criticality safety.
15.4.3 Pellet Sintering Pellet boats are stoked one high into electrically-heated, hydrogen-
~
nitrogen atmosphere, sintering furnaces. The safe slab geometry is maintained through the furnace.
Tri-level safe slab storage is used for the boats of pellets exiting the furnaces.
15.4.4 Pellet Grinding Pellets are removed from refractory metal boats by upending into a hooded vibratory feeder bowl which has the geometry of a safe slab.
The grinders which are also equipped with ventilated enclosures, size the pellets to final diameter. The pellets then are water-washed to remove grinding dust, dried on a moving belt conveyor, and inspected for dimensions and flows. The acceptable pellets are loaded onto open metal trays, stacked, and weighed for storage.
Finely divided UO2 from the grinding operation is caught in the grinder coolant and is removed as a wet cake by means of a centrifuge.
The centrifuge and associated tank are critical'y safe by virtue of safe geometry.
The UO2 cake is dried in a ventilated oven and removed from the centrifuge bowl in a hood attached to the bowl drying oven. All scrap pellets and dried sludge from grinding are weighed and handled in waled 5-qallon metal pails in safe batch quantities.
AMENDMENT APPLICATION DATE:
PAGE NO.:
May 1987 15-8 XNW F-FOI-822 (2/87) a
s ADVANCEDNUCLEARFUELSCORPORATION Xi+2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRATION REV.
15.4.5 Pellet Storage Troys of finished pellets are stacked ten high and placed three stacks to a metal pallet.
Side-to-side separation between trays on the pallets is maintained by metal spacers welded to the tops of each pallet and loaded pallets are stacked in open metal rocks which maintain physical separation between pallets side-to-side, as well as vertically.
Criticality safety is provided by this physical separation and by the presence of the stainless steel storage trays interspersed through the layers of pellets.
The storage system has been designed to meet seismic zone ll require-ments.
15.5 Rod Fabrication Fabrication of uranium fuel rods requires various processing and inspec-tion steps including outgassing, loading, welding, leak check, assay, x-raying, etching, autoclaving, final inspection and storage. Because of the form of the uranium oxide (i.e., large ceramic pellets), hooding and special ventilation is required for only the first process steps, outgassing and loading.
15.5.1 Pellet Outgassing and Storage Stacks of pellet trays are moved from the storage area to the outgas furnaces on roller conveyors which have provisions to contain any chips or contamination which may be on the trays.
The tray stacks are processed through the hydrogen-nitrogen atmosphere, roller hearth furnaces in a geome-trically safety end-to-end aicay. Gases from the furnaces are discharged to the building exhaust system af ter HEPA filtration and the room and ductwork are continuously monitored for hydrogen buildup.
Outgassed pellets are stored in an enclosed storage cabinet to provide o queue chead of the rod loading operation. Criticality safety is achieved by storage in a fixed array with side-to-side and top-to-bottom separation
. maintained between tray stacks.
Special protective clothing, with exception of gloves, is not required in this and subsequent processing areas. Monitoring of equipment surfaces and the floor is performed to detect contamination. In addition, air samplers are located throughout the area to detect any airborne contamination.
15.5.2 Rod Loading Ventilated, HEPA filtered boxes are used for containment during the rod loading operation.
An end-to-end, single line fixed orrov is used in the loading hoxes to assure criticality safety.
Tho use of nega tive pressure relative to the outside assures containment of any uranium oxide dust AMENDMENT APPLICATION DATE:
PAGE NO.:
May 1987 15-9 XN-NF501422 (21871
[
s
ADVANCB3NUCLEARFUELSCORPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRATION REV.
generated during loading within the box.
No special protective clothing is required. HEPA filtered exhaust is provided in the rod fabrication area to maintain the area negative with respect to atmosphere.
15.5.3 Rod Welding Following loading, rods are moved to the adjacent welding stations. The rods are maintained in a single layer array to provide a slab of critically safe dimensions.
The rod ends are decontaminated and the final weld is made, sealing all uranium materials within the rods. Rods are placed in metal trays having a depth of less than 3.5 inches to provide critically safe sicb geometry during transport and storage.
15.5.4 Rod Leak Check Rods are placed in the leak check chamber, one tray at a time. Safe slab geometry is achieved by limitation of the tray to 3.5 inches depth.
15.5.5 Rod Assay and X-Ray Rods are removed from trays and processed individually through the rod assay station. The discharge from this station which acts as a feed queue for the x-ray station is in the form of a single layer of rods. Rods discharged from x-ray are collected in a single metal tray. Thus, the criticality safety of both work stations is assured by maintenance of a safe geometry sicb of less than 3.5 inches.
Both the assay system, and the x-ray machines, are potential sources of radiation and are heavily shielded with lead encased in steel. Operator access to the machine internals, and thus to accidental exposure to radiation, is limited in the case of the assay equipment by the size and location of the rod entry and exit ports. Where the operator must regularly have access to the inside of the x-ray machine to change film and perform other tasks, access doors are electrically interlocked to prevent operation of the x-ray
.with the access door open.
A second x-ray unit, configured as a walk-in booth, is housed in a lead-lined, steel enclosure with a powered sliding door.
Warning lights and interlocks between the door and the x-ray head are provided to prevent accidental exposure to personnel.
15.5.6 Rod Cleaning and Etching Following NDT, the fuel rods are transferred in t r oys to sterone.
Trays are stored on enclosed conveyors which maintain the fuel in a series of geometrically safe slabs separated at vertical intervals of 15 inches.
AMENDMENT APPLIC ATION DATE:
P AGE NO.:
May 1987 15-10 X NW F-FO t.822 (2/87) s
O ADVANCEDNUCLEARFUELSCORPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRATION REv.
Rods are removed from these trays and transferred to the etch room or i
bundle assembly by cart. Criticality safety in this area is by batch control which is achieved by limiting the number of rods in the area.
The etch room is equipped with a separate of fgas scrubber and filter system used to treat any fumes given of f by the hydrofluoric acid etch solution and stop etch bath. Special protection is provided for the operator including rubber gloves, face shield, and rubber apron.
15.5.7 Rod Autoclaving Rods discharged from the etch room are loaded into autoclave baskets.
These stainless steel baskets limit the fuel rods within a 10-inch diameter circle.
A monorail system is used to transport loaded baskets from the loading i
station to a storage rock.
This structure, designed for seismic zone 11, I
maintains the baskets in a fixed array to prevent a critical interaction between the baskets.
A single loaded basket is positioned in each autoclave by means of an overhead hoist which interf aces with the basket storage array.
The rods are subjected to a high pressure, high temperature steam cycle. Both temperature and pressure are automatically controlled and carefully monitored to assure that the autoclaves are operated within nameplate limits. Rupture discs are provided along with an over-temperature shutdown for each autoclave for protection in case of control failure.
15.5.8 Final Rod Inspection Baskets of autoclaved rods are moved from the storage array to final inspection.
Here, the rods are removed from the basket in groups of J
approximately 50 and positioned in a plane array for inspection. Fol;owing inspection, the rods are loaded in metal storage trays and moved by roller
. conveyor to final storage.
The use of safe geometry slab configuration is used at this work station to assure criticality safety.
15.5.9 Final Rod Storage Fuel rods are stored in metal trays in an enclosed storage array to await release for the bundle assembly operation. This array is in the form of a series of safe geometry s! abs separated by a vertical distance of 15 inches.
15.5.10 Rod Downloading A special facility is provided in the rod loading orea to allow down-loading of rods.
AMENDMENT APPLICATION DATE:
P AGE NO.:
Mov 1987 15-11 X N-N F-FO1822 (2187)
)
1
)
ADVANCEDNUCLEARFUELSCORPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKE' NO. 70-1257 PART 11 - SAFETY DEMONSTRATION R Ev.
The uranium f rom rods is recovered by removing an end cap and dumping the pellets into a 5-gallon metal poil within a hood for return to the scrap recovery operation. The hood is exhausted through a HEPA filter and air sample heads are located at this station to monitor for airborne contamination.
Protective clothing, gloves, and shoe covers are required-while working in the downloading station, and survey equipment is located at its exit.
Safe slab geometry is used to maintain a critically safe work station, and pellet containers are limited to safe batch quantities.
15.6 Neutron Absorber Fuel Rod Fabrication in order to preclude the possibility of accidental mixing of fuel contain-ing gadolinia or boron with standard uranium oxide fuel, neutron absorber fabrication (NAF) is performed in a separate f acility within the Specialty Fuels (SF) Building.
For preparation of gadolinia-uranium pellets, UO2 pcwder is transferred to the NAF area in 45-gallon drums and off-loaded into a blender where the gadolinio powder is added.
The blended powder is then milled, compacted, granulated, lubricated, and pressed into pellets.
Each pellet has a special gadolinia marking to distinguish it from standard pellets.
Following the pelletizing operation, carefully identified boats of pellets are transferred by enclosed cart to the UO2 Building sintering area. The boats are then botched through a selected sintering furnace, immediately removed from the furnace creo, and returned to the NAF facility. The pellets are then ground in the NAF grinder, outgassed, loaded into rods, and seal welded.
Af ter a check for contamination, the rods are transferred to the UO2 Building by cart where these rods join the processing of standard UO2 rods at the leak check work station.
The processes. equipment and controls used in the NAF f acility are similar to those previously described for these operations in the UO2 Building.
Criticality safety is assured in the NAF facility using a combination of moderation control, safe slab geometry, safe geometry arrays, and safe batch control.
AMEtJDMErJT APPLIC ATIOtJ DATE:
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ADVANCEDNUCLEARFUELSCORPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRAT10!'l
- ggy, B C-Al O3 rods are fabricated completely within the SF Building (loca-4 2
tion of the NAF area). Pellets fabricated of f-site are outgassed, loaded in rods, and seal welded before being moved to the UO2 Building for inspection and assembly.
15.7 Bundle Assembly The bundle assembly operation is comprised of several operations, rod picking, assembly, inspection cleaning, storage and packing.
15.7.1 Rod Picking and Assembly Rod trays are removed from final storage and placed on an order picker.
The order picker maintains two layers of rod trays in safe geometry slabs, separated by 15 inches vertical spacing. The order picker is used to deliver rods in the required sequence for assembly into bundles.
A powered X-Y table is then used to insert rods into the fuel bundle being fabricated.
15.7.2 Inspection. Cleaning and Packaging Af ter a bundle is assembled, it is inspected, cleaned by washing if warranted, and dried with warm air.
A protective plastic sleeve is placed around each completed bundle and it is moved to storage or to the packaging station. In contrast to the rest of the assembly area which relies on the limited quantity, spacing and enrich-ment of the UO2 fuel present to assure criticality safety, the bundle storage array makes use of neutron absorber (Boral) sheets to minimize the interaction between fuel assemblies.
During packaging, fuel assemblies are placed into inner shipping containers in a vertical position. These are then lowered into a horizontal position inside the outer shipping container. Sealed, loaded outer containers are removed from the building using a forklif t and taken to the shipping /stor-age area.
15.8 Scrap Recovery Scrap UO2 powder and pellets are recovered by two routes, one dry and one wet, in each case, the initial processing step is oxidation of the UO2 IO U0-38 15.8.1 U Og Facility 3
Scrap uranium oxide enters the t J Og f acility in either pellet or powder 3
form in 5-gallon poils. Each bucket is limited to a single safe batch and most be certified dry (less than or equal to 10,000 ppm moistore).
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ADVANCEDNUCLEARFUELSCORPORATION XN-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 PART 11 - SAFETY DEMONSTRATION REV.
The scrap is removed from the buckets inside of hoods, placed in metal trays (limited to a single safe batch), and oxidized in high temperature furnaces.
Care is taken to avoid enrichment mixing. The U 03 8 produced is then screened to remove klinkers and gravity discharged into a 45-gallon powder container 'or into a 5-gallon bucket.
Since the material is dry entering the U 038 f acility and is processed through a furnace, no further moisture analysis is required.
Powder drums are weighed, blended and sampled to verify purity and enrichment as required for further processing steps and identified as dry powder.
In addition to the use of ventilated hoods mentioned above, personnel are required to utilize protective clothing including coveralls, rubber shoe covers, plastic gloves, and eye protection.
15.8.2 UNH Facility Oxidized scrap powder which is not dry blended with virgin powder may be processed through the UNH facility.
In this facility, uranium oxide is pneumatically transported from drums or buckets using a negative pressure conveying system to powder receivers located above each dissolver.
The powder receivers are lim!ted in volume and operate in conjunction with a scale system to control the quantity of powder batched into the dissolvers to assure criticality safety.
A nitric acid / water mixture is heated in the dissolver and pumped over the uranium oxide powder, held in a perforated metal basket until the oxide is dissolved.
The basket is inspected between batches for undissolved uranium oxide to avoid buildup of material in the dissolver.
Tank geometry and placement is carefully controlled to assure criticality safety within the UNH facility.
The uranyl nitrate is filtered and pumped to geometrically safe storage tanks where it is held until processed through a uranium conversion line.
Protective clothing and eye protection is required in this operating area.
Exhaust from the dissolver feed hoods is HEPA filtered before leaving the area and the offgas from the dissolvers is treated through a multi-stage liquid scrubber to remove NOx prios to HEPA filtration.
15.8.3 Scrap Recovery Area Where scrap is not of acceptable purity to rejoin the virgin uranium oxide processing stream, the material may be processed through the Scrap Recovery Area.
This facility has provisions for dissolving oraniom oxide and AMENDMENT APPLIC ATION DATE:
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purifying it through use of a solvent extraction system. The clean UNH from this operation is then reacted with aqueous ammonia to form ammonium diuranate. The precipitate is then centrifuged, dried, and calcined to UO, all 2
within the Scrap Recovery Facility.
As in the case of the UNH Facility discussed above', criticality safety is assured in the Scrap Recovery Area through control of equipment and tank g
locations and geometry. Batching of the dissolver is strictly controlled, and product UO2 is handled only in safe batches. Both the hooding and process equipment are exhausted through HEPA filters, and protective clothing and eye protection are required for operating personnel safety.
15.8.4 Cadolinia Scrap Recovery A separate facility is provided in the ELO Building for recovery of gadolinia scrap from the NAF operation.
This f acility, equipped with a dissolver, filtration equipment, and solvent extraction system, produces gadolinia-free uranyl nitrate. The uranyl nitrate may be converted to UO2 in the Scrap Recovery Area or in either conversion line.
Criticality safety in the gadolinia recovery facility is provided by control of the geometry of the solvent extraction equipment and the dissolver as well as through control of feed and product solution uranium concentration (mass).
A HEPA filtered exhaust hood is provided around the dissolver and protective clothing and eye protection are required for personnel operating in the area.
Survey equipment is provided at 'the exit of this area to monitor hands, clothing, and feet on egress.
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