ML20203K045
| ML20203K045 | |
| Person / Time | |
|---|---|
| Site: | Framatome ANP Richland |
| Issue date: | 12/08/1997 |
| From: | Edgar J SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER |
| To: | Weber M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| JBE:97:174, TAC-L30940, NUDOCS 9712220183 | |
| Download: ML20203K045 (18) | |
Text
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. SiEMENS
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ral A t December 8,1997 JBE:97:174 U S. Nuclear Regulatory Commission
-l M-e Attn: Mr. M.F. Weber, Chief Licensing Branch Division of Fuel Cycle Safety and Safeguards, NMSS Washington, DC 20555 -
Dear Mr. Weber:
Ref:
Letter, K. J. Hardin to L. J. Maas, " Criticality Page Changes (TAC No. L30940)," dated December 1,1997.
Enclosed, per the request in the referenced letter, are six copies each of pages 15 35 through 15 37d from SPC's informational submittal of April 15,1997. We apologize for not including them with that submittal.
Per my conversation today with Harry Felsher of your staff,it was determined that page 15 30a was included with Siemens Power Corporation's (SPC) Informational submittal of January 13, 1997 and is, therefore, not resubmitted herewith.
With regard to the number of category 11 criticality safety analyses (CSAs) included in SPC's k
informational submittals of CSA summaries, the tabulation below provides the number included for each submittal.
~ Submittel Dete No. CSA's included 10/2/95 5
1/13/97 2
3/17/97 8
-4/15/97 6
-4/30/97 9
Finally,' the referenced letter refers to these submittals as " requests", contrary to how previous
- Part 11 submittels have been treated. In fact, they are informational as committed to by SPC for 971222018397Mt57:
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2101 Horn Rapids Road Tel:
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. Michael F. Weber JBE:97:174 December 8,1997 Page 2 inclusion in Part il of our license. As in the past, we are willing to discuss questions you may have about them.
Very truly yours, James. Edgar Staff Engineer, Licensing
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' Siemens Power Corporaion Nuclear Division sw.2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 701257 l
PART 11. SAFETY DEMONSTRATION l ngy, l
15.1.11 Bundle Assembly 4
The bundle assembly area consists of all equipment needed to assemble tie plates, l
spacers, fuel rods, and other related hardware into completed fuel assemblies and to prepare those assemblies for shipment to the customer. (The terms " assembly" and
" bundle" are used interchangeably in this discussion). The primary components of this system are the rod order picker, bu' idle assembly tables, final assembly tilt tables, bundle inspection stations, bundle washing and drying stations, bundle storage aren, and shipping container loading area. The equipment is located in Room 193 of the Uo Building.
Trays of fuel rods are pulled from final rod storage onto the storage elevator and then transferred into one of twelve locations on the rod order picker. Individual rods are pulled from the rod order picker and inserted into spacers and/or cage assemblies fixed on either of two bundle tilt tables. When assembled, fuel bundles are raised, using tha tilt tables, to a vertical position. The bundles are then moved
' from the tilt tables to one of the two inspection slabs using an overhead bridge crane. After being inspected, bundles are either moved directly into storage racks.
or are washed and dried.
The bundle wash station is located in the reactor control cluster (RCC) gage pit and may be used to clean one fuel assembly at a time concurrently with RCC inspection. Washing consists of lowering a single assembly into a vertical tank which is then filled with a cleaning solution which is predominantly water. Each bundle is rinsed as it is removed and then transported to a bundle drier using the bridge crans. The bundle drying unit, located north of the bundle wash pit, blows hot air across the bundle unit untilit is comp'etely dry. The bundle is then removed from the drier using the bridge crane and transferred back to the RCC pit for inspection and then to a specially modified lift truck to transport the bundle into the storage racks or to the bundle packaging area. The bundle storage area is a vertical storage arrangement of fuel bundles.
The bundle packaging area has a tilt table that tilts the BWR shipping container into the vertical position for loading.
The loaded container is then lowered to the horizontal position where it is completed and readied for shipment.
The PWR shipping container has its own tilt mechanism built into the container.
! 15.1.11.1 Criticality Safety
- Criticality safety in the bundle assembly area depends upon enrichment control throughout the eres; geometry and moderation control at the rod order picker; geometry and spacing control on the assembly tables; geometry, spacing, and 4 AWENLAsENT As% CATION DATE
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April 15.1997 15-35 sPC ND 3330 947 (Ra4712)
Siemens Power Corporat!on - Nuclear Division mg.i SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227. NRC DOCKET NO. 701257 PART 11 - SAFETY DEMONSTRATION
!REV.
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l moderation control for fuel assemblies, the inspection station, and the bundle wash l and drying stations; and spacing control and neutron absorbers in bundle storage, j
Rod Order Picker l
The rod order picker is a motorized cart that holds 12 rod storage trays in a two tiered by six wide array and is used to stage the various types of rods to be used in a fuel assembly. Criticality safety depends upon enrichment, geometry (rod slab thickness), and moderation (keeping water from flooding between tray levels)
Control.
Summary of Accident Conditions The accident conditions evaluated are overstecking all trays in the rod order picker, fully flooding the rod storage trays, and placing moderating materials between the layers of rod trays. The accident condition that has the largest impact on k.,, is placing moderating material bc! ween the layers of rod storage trays.
i The possible mechanisms of getting moderating material into the rod storage trays are:
Hydraulic fluid from the rod elevator, 6
Water leaking from overhead solution lines, Water used in fire fighting; and Placing plastic or other moderating materials in the rod storage trays.
Hydraulle fluid from the rod elevator was considered as a potential source of moderating material in a rod storage tray. The hydraulic tank for the rod order
! picker contains less than 130 liters based on field measurements.
Assuming the rods in a storage tray have a void fraction of 0.17 (0.30 is typical),12 storage trays l filled with rods could possibly be filled with hydraulic fluid. The rod storage trays are open ended se that any significant liquid depth in the trays will cause the liquid to spill out onto the floor. There is no credible means to retain 3.6 inches of liquid in the rod storage trays.
l Water from overhead lines was considered. Where the cage storage cabine not prevent sprays from the overhead water lines from spraying or dripping onto the I rod storage trays, the overhead water lines are shielded. Also, the rod storage trays are open ended so that any significant liquid depth in the trays will cause the liquid
- to spill out onto the floor. There is no credible means to retain 3.6 inches of liquid in the rod storage trays.
S AMENDu(NT APPUCATO,4 DATE:
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' Slem:ns Powcr Corporation Nuclear DMsion Eur.2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 701257 r
l PARTll SAFETY DEMONSTRATION ngy. l i
i Water from fire fighting was considered, Fire fighting in the area would result from an unlikely initiating event. The use of liquid water in this area is expected.
However, even if foam were to be used, the water density in the foam is not high j
enough to approach even 5 volume % water. The rod storage trays are open ended so that any significant liquid depth in the trays will cause the liquid to spill out onto the floor. There is no credible means to retain 3.6 inches of liquid in the rod storage trays or to exceed 5 volume % interspersed moderator during the fire fighting scenarios.
i
' Plastic between rod storage trays was considered. The only mechanism identified that can cause criticality in the area is to fill the void spaces between layers of rod storage trays with significant quantities of plastic. Moderating materials normally present in the process are tags and labels that ars occasionally placed in small plastic folders. Styrofoam cage holders are routinely used on or near the rod order i
picker. Metal sheeting on the top of the rod order picker prevents this material from falling in between rod trays. The only way for significant quantitles of moderator to be placed in this area is for an individual to deliberately place them there. Criticality safety training for this area stresses moderation control.
l Bundle Assembly Tables. Tilt Tables and insoection Stations e
Criticality safety at the bundle assembly tables, tilt tables, and inspection stations depends upon enrichment (5% maximum), geometry (assembly envelope, assembly.
maintained rod spacing, pellet diameter, and clad thickness), spacing (from rod trays and other assemblies), and moderation controls.
Summarv of Accident Conditions The only accident that can cause unacceptable k,,, (>0.97) with fuel assemblies is
! full flooding and reflection.
l With the exception of a major dam on the Columbia River failing, no mechanism was l found that could cause flooding in the building to the extent needed to fully moderate and reffset fuel bunJles on the assembly tables or in the fuel bundle i inspection stations, it is possible although unlikely, that a fuel bundle could be dropped on the floor. It is not credible that a dropped bundle would be flooded before it could be picked up off of the floor.
i f AwEN0p(NT APPUCAT(PiOATE:
peg e April 15,1997 15-35b sPC No 3330 947 (R4C792) l p
9 Siemens Power Corporation Nuclear Division surf SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 701257 4
PART ll 5AFETY DEMONSTRATION
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e RCC Pit and Bundle Washina and Drvina Stations Criticality safety at the RCC inspection station and bundle washing and drying stations in the RCr; pit are the same as for fuel assemblies discussed previously as well as a limit of three assemblies in the aras (one in each station).
Summary of Accident Conditions i
The bundle dryer station is bounded by the analysis of single bundles. The bundle wash station and RCC inspection station are adequately suberitical based on fuel
_ assembly number, isolation and separation.
The worst _ case condition in the RCC/ bundle wash station is full flooding of a bundle, which happens as a matter of practice in the bundle washer. The biggest concern in this area is washing a single PWR bundle with a volume of water to volume of fuel (V,,/V,) ratio between 3 and 4. Even though the k,,, for this condition I exceeds 0.97, it is still substantially suberitical. Administrative defenses against
- this condition include not allowing bundles to be removed from the assembly tabla l until inspection confirms that all rods are in designed locations, overchecking of design parameters, and requiring special controls on any fuel bundles brought back into the shop for rework.
I Bundle Storaae Criticality safety at the bundle storage area depends upon bundle spacing and neutron absorbers in the storage racks as well as the enrichment, geometry and moderation control and compliance with assembly design specifications.
The neutron absorbers consist of boral (boron aluminum) plates between storage rows 2
with a certified B 10 area density of at least 0.02 gm/cm.
Summarv of Accident Conditions PWR Assemblies Loss of bundle to bundle spacing and simultaneous full flooding are the worst postulated conditions.
However, the simultaneous occurrence of these two conditions is not credible.
I Other unacceptable conditions are:
I Placing plastic shipping shims into PWR fuel assemblies; Plastic sheathing used to wrap bundles fill with water; Enrichment limits on PWR fuels are exceeded and bundle storage area is optimally moderated / fully flooded;
- l A44N0t*(NT APPLCATeoN DATE:
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1 April 15,1997 15-35c i
sPC ND 3330 947 P407 92) 1
. ' Sle' mens Power C:rporation Nucle ^r Division eur.2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227. NRC DOCKET NO. 701257 i
PART ll. SAFETY DEMONSTRATION l ncy.
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I The limits on V.,N, ratio are exceeded during full flooding,........um moderation; Missing or damaged neutron absorber plates; and i
Loss of spacing due to rack failure, i
Each of the first four conditions above must be controlled administratively (e.g., the plastic sheathing used to wrap fuel bundles is required to be open at both ends to facilitate drainage). Administrative controls are justified in this area because (1) the I
initiating events that are required before these conditions exist are highly unlikely and (2) the entire fuel assembly process has multiple overchecks by Operations and Quality Assurance to ensure that assemblies meet design specifications.
The fifth and sixth conditions rely on the system design and routine inspection. The neutron absorber plates are an integral part of the storage rack and are readily visible. For the neutron absorber plates to be missing would requi ; deliberate disassembly. Configuration control practices ensure any disassembly is reviewed before it takes place. The rack was designed to withstand accelerations up to approximately 0.2 g. This covers impact by transfer carts and seismic events. UBC l earthquakes for this region (Zone 28) only require structures to withstand an acceleration of.20 g.
Any rack damage will be readily visible to Operations and Criticality Safety personnel who frequently inspect / audit activities and equipment in the bundle assembly area.
Summary of Accident Conditions BWR Assemblies The accident scenarios for BWR assemblies are much the same as discussed previously for PWR assemblies except for smaller consequences because of smaller assemblies. The PWR analyses bound the BWR scenarios, Shiocina Container loadina Area e
Criticality safety in the shipping container loading area depends upon enrichment, j moderation, and spacing control and adherence to the fuel assembly design
' specifications.
I Summarv of Accident Conditions The accident conditions evaluated for bundle storage bound the shipping container loading area.
1
. Autteouf h1 ApptCAfiON DATE:
P AGE NCL:
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April 15,1997 15 35d sPC.No 3330 947 (R407$2)
'(l Siemens Power Corporation - Nuclear Division sup.2 i
SPECIAL NUCLEAR MATERIAL LICENSE NO SNM 1227, NRC DOCKET NO. 701257 '
'(
PART ll.5AFETY DEMONSTRATION
- nev, 15.1.11.2 Radiation Protection Rindle assemb.y is performed in a radiation area. Tnis area is operated at a pratsure slight!'/ below atmospheric to preclude egress of altborne contamination.
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The _'aranium 8.1 the bundle assembly area is contained in welded rods and so does l l
not pose problems with generating airborne contamination.
l t
15.1.11.3 Fire Protection The UO building is rated as noncombustible. Fire loading is kept to a minimum through monthly inspections. Fire extinguishers (dry chemical or CO ) alarm pull 3
boxes, and heat detectors are strategically placed throughout rod testing area.
Where moderation controlis in place, high expansion foam, dry chemical or CO are required to be used to combat a fire.
1 All flammable and combustible liquids of greater than one pint in volume used in the process are stored in fire rated containers.
- 15.1.11.4 Environmental Safety i
The concrete floors are sealed to be liquid tight and contain no floor drains. Room
! 193 is serviced by a "once through" HVAC system that is continuously monitored for radioactive contamination. The exhaust systems for Room 193 are double HEPA filtered and have deluge systems to protect the final filters from fire, i
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AutNOWENT APPLCATONDATE:
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l Sisinens Power Corporction Nuclear Division cup.2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 701257 PARTll. SAFETY DEMONSTRATION nev.
15.1.12 Process Offnas (POG) Systems 15.1.12.1 Line 1 POG System The Line 1 Process Offgas (POG) system begins with process equipment exhaust vents !
and ends at the discharge of the HEPA filters and includes the followintj major system components:
- 1. Line 1POG ducts including the g inch to 8 inch "Y" section and all POG l-ducts, joints and "Y" sections.
The Line 1 POG system is located in the northeat,t corner of Conversion Line 1 in the
, UO: Building. The tall scrubber solution tanks span two rooms,131 (first floor) and 210 (second floor).
} The POG routes all gas discharged in Conversion Line 1 to two scrubbers where all gas
- from the tanks, dryer, calciner offgas (COG) system and the Vaporization Room is contacted with water to remove uranyl fluoride, ammonia, steam, ammonium nitrate, ammonium fluoride and any particulate uranium that may be airborne. Separators at the scrubbers' discharges separate the gas and water. The water is continually recycled to the ADU conver-lon line recycle tank and fresh water is continually added to the L
i scrubber solution tanks. After the exhaust air is scrubbed, it is heated above its dew point and then passed through two stages of HEPA filtration before it is discharged to the atmosphere, 15.1.12.1.1 Criticality Safety i
i l Criticality safety in the Line 1 POG system depends upon the use of favorable geometry, geometry control by design features, U density control by process, and enrichment control and spacing.
POG Ducts and 9 inch to 8 inch "Y" Section
]
e i
Criticality safety in the POG ducts depends upon the uranium density in any compound in the system to be a maximum of 5.5 g U/cc as achieved by the design and operation of i the Line 1 conversion equipmer.t. It also depends upon keeping other fissile material at
-least one foot from the ducts and that the ducts be cleaned at least quarterly to limit uranium buildup, Except for the 11 inch transition duct between the scrubber and "Y"
. section and vaporization isolation header, all ducts must be nine-inches or less I.D.
! Criticality (liquid) drains, as discussed later, must be tested annually for operability,
&a4NonstNT APPLCATON DATE2 PAGE NO.:
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SPECIAL NUCLEAR MATERIAL UCENSE NO. SNM 1227, NRC DOCKET NO. 701257 a
PART il.8AFETY DEMONSTRATION nev. l l
1 Summary of Accident Conditions i
The primary criticality safety concern with the Line 1 POG system is that the POG ducts provide a potential path for migration of U compounds. The following were Identified as being unfavorable receptacles for the ADU compounds which could migrate through the POG vent lines: 'ho cylinder wash tank, the dilute nitric acid (DNA) tank and the t
vaporization ches'. The cylinder wash tank is also a potential pathway to the lagoons.
These three locations, described in other sections, require elsvated
- isolation headers" equipped with criticality drains on the POG vent lines to isolate them from the rest of the POG vent system. PM's are required to assure the criticality drains remain functional.
-Individual tank drains are also required for the cylinder wash tank to prevent one tank from overflowing into u,... ext while transfer to a lagoon is occurring.
A cross connection between the Une 1 and 2 POG systems is located on sections of POG ducts which are isolated from the potential sources for U compound migration by POG criticality drains. This cross connection contains multiple barriers against U migration, j
l Five POG criticality drains have been placed on the POG ducts to prevent solut from migrating from vessel to vessel via the POG ducts. The isolation headers of the POG header provide isolation between the high U bearing vessels and unfavorable geometry equipment. This design is required to prevent the backflow of U compounds into these unfavorable geometries. The backflow is prevented by multiple barriers including use of tank criticality drains, POG duct criticality drains and the elevation of the isolation headers of the POG header in relation to the other vents on the system. In addition, liquid level controlis used for many of the tanks to limit overflow potential.
I Optimum moderation of an ADU water mixture in the ductwork with supports in place to i
maintain spacing between ducts and full reflection was evaluated and resulted in a k, below 0.95.
POG. Scrubbers and Seoarators. HEPA Filter Ducts and HEPA Filters Criticality safety in this equipment depends upon enrichment control (5% maximum),
geometry (depth) control in the separs. tors, spacing (one foot minimum) of fissile material from equipment and ducts, criticality drains being operable, and the scrubbers operating when process equipment vented to the FOG system is operating, in addition, HEPA filters are examined for discoloration when they are changed.
1 i AuOsDW(ast APPLCATON DATE; PAGE 84:
l April 15,1997 15 36 a
$PC ND 3330 947 (A407 921
_4,
Siernens Pow:r Corporation Nuclear Divisi:n wr.2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 701257 I
PART11 SAFETY DEMONSTRATION
- nev.
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j Summary of Accident Conditions i
i The HEPA f!ter housing is an unfavorable geometry vessel; however, the POG scrubber l I
Is designed to prevent any significant quantities of uranium compounds from ;
accumulating there. No accident pathways have been identified which would result in significant quantities of uranium being deposited in the HEPA filter or in the housing while the scrubber is operational. Therefore, operation of the scrubber is required when the POG system is operational. As an added measure to assure that system conditions have not changed, a visualinspecticn of the HEPA filters is required each time ^ey are changed. The material normally collected on the HEPA filters is a white powder resulting from the crystallization of gaseous ammonia compounds with trace amounts of uranium.
Significant uranium compound contamination would cause noticeable discoloralico. Therefore, !t is specified that the material be analyzed for uranium content where noticeable discoloration is observed. The ductwork between the scrubber and the HEPA filters requires annualinspection for accumulation of materials and analysis of uranium content to reconfirm that significant quantities of uranium are not being deposited in the unfavorable geometry ducts.
The criticality drains on the separator boxes are designed to limit the liquid level to six i
inches under maximum flow.
These drains consist of two, inch lines with the centerlines located 4.5 inches above the separator boxes' bottoms. The separator unit has been shown to be adequately suberitical when filled to 22 cm (8.66") with an optimum ADU/ water mixture, but not when completely full, hence the requirement for properly placed criticality drains. Accumulation of a 30 kg of U compounds in the POG duct work was identified as a potential source for migration of unacceptable amounts of non liquid material to the separator box when the scrubber is off line. The scrubber is required to be operational when the process equipment is cperating to remove the normal airborne material. The material which accumulates in the ducts becomes a solid and is not physically prone to migration without an outside force acting upon it to loosen it. Therefore, the ducts are required to be cleaned quarte:rly with scrubbers on line to minimize buildup. In addition, the surveillance of HEPA filters when changed confirms that material is not migrating to the filter box.
A UF. gas release into the POG system was considered as a potential source for accumulation of uranium compounds in the filter housing. The PO, scrubbers are designed to remove particles greater than 5 microns in size. Particles less than 5 microns (e.g., UF.) remain airbome and plug the filter medium before significant accumulations can occur in the housing. Operati'q experience with UF. Introduction into the POG verifies this system impact.
l avcio u o n a m c c m n os-moo.:
April 15,1997 15 36 b sPC440 3330 947 (RM? 9h
SiemenS Power Corporation - Nuclear Division EMF 2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 701257
.l l! nev. l PART ll. SAFETY DEMONSTRATION I
15.1.12.1.2 fipdiation Protection I
Chemical Conversion is performed in a controlled access, radiation controlled area.
Personnel entering or working in the area, who require monitoring under 10 CFR 20.1502(a), are required to wear radiation monitoring devices and protective clothing / equipment (rubber shoe covers or equivalent, plastic gloves, coveralls, eye protection, respiratory protection) as appropriate for the work to be performed.
Personnel are required to survey themselves prior to exiting the controlled area.
Equipment leaving the controlled area must be released by Radiological Safety personnel. All personnel also receive initial and yearly refresher training on radiation protection principles and requirements.
Airborno uranium contamination is controlled by extensive use of hoodh and sealed process equipment which are maintained at negative pressure and HEPA filtered prior to entering the main exhaust ductwork. Examples of such hoods are the Line 1 Utihty Hood and Hydrolysis Hood.
I Routine surveys are performed and housekeeping practices are enforced to minimize i
surface and airborne contamination in the chemical conversion area.
Air is j
continuously sampled and periodically analyzed to detect any airborne contamination.
Urine sample analyses and lung counts are periodically performed for personnel who work in the controlled access area. The frequencies of such tests are described in Chapter 3.
15.1.12.1.3 Fire Protection The Uo, building is rated as noncombustible. Fire loading is kept to a minimum j through mor.thly inspections. Fire extinguishers (dry chemical or CO ), alarm pull 3
' boxes, and heat detectors are strategically placed throughout the chemical conversion area. Where moderation control is in place, high expansion foam, dry chemical or CO are required to be used to combat a fire.
15.1.12.1.4 Environmental Safaly Hazardous materials are contained to prevent their introduction into the I
environment. Hoods are maintained at a negative pressure and HEPA filtered prior to entering the main exhaust ductwork. Floors are sealed and have no drains.
- All room and building air is processed through the heating, ventilation, and air conditioning system and then HEPA filtered to remove particulates.
l jac c e. tam cato.o m eaos e:
April 15,1997 15-36c sPCho 3330 947 (%07 th
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SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 701257 l
PART 11. SAFETY DEMONSTRATION nev.
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Solvent rags from the controlled area are disposed of in special containers l
distributed throughout the powder preparation area. The rags are treated as mixed hazardous waste and stored in a secured area for future disposal.
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j *wantamcatmoats; nos e April 15.1997 15-36 d 1
SPc NO 3330 947 (R 19712)
- Siemens Pow;r Corporation Nuclear Division sp.2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 701257 7
PART ll. SAFETY DEMONSTRATION
_ nev.
I 15.1.12 Process Offnas (POG) Systems 15.1.12.2 Line 2 POG System The Line 2 Process Offgas (POG) system begins with process equipment exhaust vents and ends at the discharge of the HEPA filters and includes the following major system components:
1)
Line 2 POG ducts including the g inch to 8 inch *Y" section and all POG ducts, joints and "Y" sections; and 2)
POG scrubbers / separators, scrubber solution tank, demister, HEPA filter s
ducts and HEPA filters.
The Line 2 POG system is located in the Conversion Line 2 mezzanine in the UOr Building.
The POG routen all gas discharged in Conversion Line 2 to 'wo scrubbers where all gas from the tanks, dryer, calciner offgas (COG) system and the Vaporization Room is
- contacted with water to remove uranyl fluoride, ammonia, steam, ammonium nitrate, ammonium fluoride and any particulate uranium that may be airborne. Separators at the scrubbers' discharges separate the gas and water. The water is continually recycled to the ADU conversion line recycle tank and fresh water is continually added to the scrubber solution tank. After the exhaust air is scrubbed, it is heated above its dew peint and then passed through two stages of HEPA filtration before it is discharged to the atmosphere.
15.1.12.2.1 Criticality Safety Criticality safety -in the Line-2 POG system depends upon the use of favorable j geometry, geometry control by design features, uranium density control by process, and enrichment control and spacing.
POG Ducts and 9 inch to 8-inch "Y" Section j Criticality safety in the POG ducts depends upon it e uranium density in ary compound in the system to be a maximum of 5.5 g U/cc as ach,eved by the design and operation of the Line 2 conversion equipment, it also depends upon keeping other fissile material at least one foot from the ducts and that the ducts be cleaned at least quarterly to limit uranium buildup. Except for the 10-inch transition duct between the scrubber and "Y" section and vaporization isolation header, all ducts are nine inches or less I.D. Criticality (liquid) drains, as discussed later, are tested annually for operability.
i AWNOWNT APPLr.ATON Datt:
P AGE NOa April 15,1997 15 37 SPC-NO 3330 947 (R*07 Sh
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Slemens Power Corporation Nuclear DMslon ew.2 SPECIAL NUCLEAR MATERIAL LICENSE NO, SNM 1227, NRC DOCKET NO. 701257 i
f PART ll. SAFETY DEMONSTRATION REv.h I
1 i
Summary of Accident Conditions I
i The primary criticality sr.foty conc iwith the Line 2 POG system is that the POG ducts i
provide a potential path for migratit, of U compounds. The following were identified as 4
being unfavorable receptacles for the ADU compounds which could migrate through the POG vent lines: the cylinder wash tank, the dilute nitric acid (DNA) tank and the i
vaporization chest. The cylinder wash tank is also a potential pathway to the lagoons.
These three locations, described in other sections, require elevated " isolation headers" equipped with criticality drains on the POG vent lines to isolate them from the rest of the POG vent system. PM's are required to assure the criticality drains remain functional.
Individual tank drains are also required for the cylinder wash tank to prevent one tank from overflowing into the next while transfer to a lagoon is occurring.
A cross connection between the Line 1 and 2 POG systems is located on sections of POG ducts which are isolated from the potential sources for U compound migration by POG criticality drains. This cross connection, therefore, is not considered a credible L
pathway for U migration.
i Five POG criticality drains have been placed on the POG ducts to prevent solutions l from migrating from vessel to vessel via the POG ducts. The isolation headers o POG header provide isolation between the high U bearing vessels and unfavorable geometry equipment. This design is required to prevent the backflow of U compounds into these unfavorable geometries. The backflow is prevented by multiple barriers including use of tank criticality drains, POG duct criticality drains and the elevation of the isolation headers of the POG header in relation to the other vents on the system. In addition, liquid level controlls used for many of the tanks to limit overflow potential.
Optimum moderation of an ADU water mixture in the ductwork with supports in place to maintain spacing between ducts and full reflection was evaluated and resulted in a k,,
3
! below 0.95. "Y" section supports are welded in place to maintain a minimum four inch
~ spacing between ducts under maximum loading.
le POG Scrubbers and Seoaratprs. Demister. HEPA Filter Ducts and HEPA Filters 1
l geometry (depth) control in the separators, spacing (one foot minimum) 4 material from equipment and ducts, criticality drains being operable, and the scrubbers operating when process equipment vented to the POG system is opeiating. In addition, HEPA filters are examined for discoloration when they are changed.
l i aut%0ut%t ANAtoN DATO PAGE c:
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- r Division eur.2 SPECIAL NUCLEAR MATERIAL L; CENSE NO. SNM 1227, NRC DOCKET NO. 701257 I
PART 11. SAFETY DEMONSTRATION
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Summary of Accident Conditions The HEPA filter housing is an unfavorable geometry vessel; however, the POG scrubber j i
is designed to prevent any significant quantities of uranium compounds from l accumulating there. No accident pathways have been identified which would result in significant quantitles of uranium being deposited in the HEPA filter or in the housing while the scrubber is operational. Therefore, operation of the scrubber is required when the POG system is operational. As an added measure to assure that system conditions have not changed, a visualinspection of the HEPA filters is required each time they are I
changed. The material normally collected on the HEPA filters is a white powder resulting from the crystallization of gaseous ammonia compounds with trace amounts of uranium.
Significant uranium compound contamination would cause noticeable discoloration. Therefore, it is specified that the material be analyzed for uranium content where noticeable discoloration is observed. The ductwork between the scrubber and the HEPA filters requires annualinspection for accumulation of materials and analysis of uranium content to reconfirm that significant quantities of uranium are not being deposited in the unfavorable geometry ducts and the demister, t
j The criticality drains on the separator boxes are designed to limit the liquid level to six inches under maximum flow.
These drains consist of two 3 inch lines with the centerlines located 4.5 inches above the separator boxes' bottoms. The separator unit has been shown to be adequately subcritical when filled to 22 cm (8.66") with an 4
optimum ADU/ water mixture, but not when completely full, hence the requiroment for properly placed criticality drains. Accumulation of a 30 kg of U compounds M the POG ductwork was identified as a potential source for migration of unacceptable amounts of non liquid material to the separator box when the scrubber is off line. The scrubber is required to be operational when the process equipment is operating to remove the normal airborne material. The material which accumulates in the ducts becomes a so!id i
. and is not physically prone to migration without an outside force acting upon it to loosen I it. Therefore, the ducts are required to be cleaned quarterly with scrubbers on line to minimize buildup. In addition, the survel!!ance of HEPA filters, when changed, confirms that materialis not migrating to the filter box, A UF. gas release into the POG system was considered as a potential source for i
! accumulation of uranlur,1 compounds in the filter housing. The POG scrubbers are 3
designed to remove particles greater than 5 microns in size. Particles less than 5 microns (e.g., UF.) remain airborne and plug the filter medium before significant accumulations can occur in the housing. Operating experience with UF, introduction into the POG verifies this system impact.
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. AUINDU(NT APMCATON DATE:
P AGI NCL:
April 15,1997 15-37 b sPC NO 3330 90 (R+0792)
Strnens Power Corporation Nucle:r Division Eur2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 701257 PART ll. SAFETY DEMONSTRATION REv.
I 15.1.12.2.2 Radiation Protection Chemical Conversion is performed in a controlled access, radiation controlled area.
l Personnel entering or working in the area, who require monitoring under 10 CFR 20.1502(a), are required to wear radiation monitoring devices and protective clothing / equipment (rubber shoe covers or equivalent, plastic gloves, coveralls, eye protection, respiratory protection) as appropriate for the work to be performed.
Personnel are required to survey themselves prior to exiting the controlled area.
I Equipment leaving the controlled area must be released by Radioiogical Safety personnel. All personnel also receive initial and yearly refresher training on radiation protection principles and requirements.
Airborne uranium contamination is controlled by extensive use of hoods and sealed process equipment which are maintained at negative pressure and HEPA filtered prior to entering the main exhaust ductwork. Examples of such hnods are the Line 3 Utility Hood and Hydrolysis Hood.
Routine surveys are performed and houstkeeping practices are enforced to minimize surfacu and airborne contamination in the chemical conversion area.
Air is continuously sampled and periodically analyzed to detect any sirborno contamination.
$ Urine sample analyses and lung counts are periodically performed for personnel who work in the controlled access area. The frequencies of such test are described in Chapter 3, 16.1.12.2.3 Fire Protection The UO building is rated as noncombustible. Fire loading is kept to a minimum 3
through monthly inspections. Fire extinguishers (dry chemical or Co ), alarm pull boxes and heat detet. tors are strategically placed thic oghout the chemical l conve,rsion area. Where moderation control is in place, high expansion foam, dry
!l chemical or CO, are required to be used to combat a fire.
15.1.12.2.4 Environmental Safety f
Hazardous materials are contained to prevent their introduction into the environment. Hoods are maintained at a negative pressure and HEPA filtered prior to entering the main exhaust ductwork. Floors are sealed and have no drains.
All room and building air is processed through the heating, ventilation, and air conditioning system and then HEPA filtered to remove particulates.
I i w e e s%t a m cat o m s:
eacs e April 15,1997 15-37 c sPc No 3330 90 (RM792)
Siemens Power Corpor; tion Nuclear Division mF.2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 701257 i
PARTli SAFETY DEMONSTRATION
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So.lvent tags from the controlled area are disposed of in special containers j distributed throughout the powder preparation area. -The tags are treated as mixed l hazardous waste and stored in a secured area for future disposal.
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' 441ENDhetNT APPLCATION DATE:
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April 15,1997 15 37 d sec.,e mo m m.ima
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