ML20125C971
| ML20125C971 | |
| Person / Time | |
|---|---|
| Site: | Claiborne |
| Issue date: | 12/10/1992 |
| From: | Leroy P LOUISIANA ENERGY SERVICES |
| To: | Jim Hickey NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| NUDOCS 9212140195 | |
| Download: ML20125C971 (59) | |
Text
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Chcylotte, NC 28201 1O04 1
December lo. 1992 Mr. John W. N. 3ickey, Chief' Fuel Cycle Safety Branch Division of Industrial and Medical Nuclear Safety Office of Nuclcar Material Safety and Safeguards U.S.
Nuclear Regulatory Commission Washingcon, D.C.
20555
Subject:
Docket'No.: 70-3070 Louisiana Energy Services Claiborne Enrichment Center Requests For Additional Information Pilc MTS-6046-00-2001.01
Dear Mr. Hickey:
Enclosed in Attachment A is additional information related to the issues in your letter to Louisiana Energy Services (LES) dated October 29, 1992.
These issues were discussed in detail at a meeting on October 23, 92.
Also enclosed are "Information 1
Only" copies of the pages of the Safety Analysis Report (SAR) that will be revised as a result of providing this information.
A formal update to the SAR will be made in the near future.
If there are any questions concerning this, please do not hesitate to call me at (704) 373-8466.
Sincerely, f/b N' Peter G.
LeRoy
=
Licensing Manager PGL/U75.122 Enclosures 1i.0009 921214C.4.95 921210 i
PDR ADOCK.07003070 4
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December 10, 1992 Mr. John W.
N. Hickey, Chief Page 2 xc:
(w/ enclosures)
Ms. Diane Curran, Esquire Harmon, Curran, Gallagher, & Spielbsrg 2001 S Street, NW, Suite 430 Washington, DC 20009-1125 Ms. Nathalie Walker Sierra Club Legal Defense Fund 400 Magazine Street Suite 401 New Orleans, LA 70130 Mr.
R. Waccom Office of Air Quality and Radiation Protection Louisiana Department of Environmelital Quality PO Box 82135 Baton Rouge, Louisiana 70884-2135
S October 29, 1992 Request for Additional Information 4.3 DLgilitieg_ Design Criteria In the November 7, 1991, CRC request for additional information (RAI) to Louisiana Energ lervices (LES), there were five questions in this area.
';uu have not yet submitted complete I
responses.
Consistent with the Advance Notice of Proposed f
Rulemaking (ANPR), Federal Recister Notice Volume 53, No. 78,
' ages 13276-13282, the NRC staff will evaluate the following:
- 1) Function of all equipment under normal operating conditions.
- 2) Function of Class I systems at design basis conditions.
- 3) Interaction of Classes I and II systems.
The mechanical or structural analysia on which such an evaluation would be based has not been provided by you.
In the absence of this information, sections 4.8 and 4.9 of the DSER cannot be prepared.
Response
[ NOTE: For ease of review, the five questions from the November 7,
1991 letter are repeated below in italics and detailed responses in bold are provided below each question.)
1.
Provide analyses (seismic, structural, etc.) demonstrating that the CEC System Class I components listed in SAR Table 4.6-1 maintain their safety function under design basis conditions.
Response
The System Class I components listed in BAR Table 4.6-1 (i.e.,
Feed, Blending, and f 'pling Autoclave air temperature protection loops, air pressure tection loops, associated panels, and panel supports) "Byss 1 Class I autoclave instrumentation" maintain their safety function under design basis conditions.
Totally separate instrumentation is used to regulate the air temperature and pressure inside the autoclaves to allow for the uranium hexafluoride inside the cylinder, which is inside of the autoclave, to liquefy.
Under expected, abnormal conditions these instruments interrupt power to the autoclave electric heaters.
The functions, during normal and abnormal operations, of the System Class I autoclave instrumentation is to provide a second line of defense against autoclave high air pressure or high temperature and explained in detail in SAR sections 6.3.1 (Feed Autoclave instrumentation), 6.3.5 (Product Liquid Sampling Attachment A A-1 I
l
t 4
Autoclave instrumentation), 6.3.6 (Blending Autoclave instrumentation) and 6,4.10 (Control Systems).
An incident in which the autoclave control system fails (i.e,
" runs away") and the autoclave heaters fail to trip off would result in the only credible, though highly unlikely accident, whereby the off-site exposure limits to uranium and hydrogen fluoride (reference NUREG-1391) could possibly be exceeded.
This scenario is explained in detail in SAR section 9.2.2.2.
Since this was the only credible incident whereby the off-site exposure limits could be exceeded, the instruments listed in BAR Table 4.6-1 were classified as System Class I, thus assuring their operability during incidents that could result in release of uranium hexafluoride.
The evaluation of possible incidents and their effect on facility equipment is discussed more thoroughly below in response to questions concerning classification of structures, systems and components.
Beyond the incidents that might impact these instruments, the instruments will also withstand the design basis natural phenomena listed in the Advance Notice of Proposed Rulemaking (ANPR).
These natural phenomena are earthquakes, high winds (i.e.,
tornadoes), and floods.
The facility can also withstand expected impact of accidents at nearby industrial, military, or transportation facilities.
The Separations Building, where the System Class I instruments are located, is designed to withstand the design basis natural phenomena (i.e., earthquake, tornado, flood).
An evaluation was l
also performed on the possible interaction during the Design l
Basis Earthquake from surrounding structures.
None of the site i
buildings (i.e., the Centrifuge Assembly Building, the Cylinder Receipt & Dispatch Building, Standby Diesel Generator Building, Office Building & Guardhouse, Pump House, Fire Water Storago Tanks, Switch Yard) at the facility impact the Separations Building during an earthquake.
The gaseous effluent stacks are located on the north wall of Plant Unit 1 of the separations Building.
Since the stacks could impact the Separations Building and the System Class I autoclave instrumentation, the stacks have been designed to withstand the design basis natural phenomena.
l
- LES has submitted detailed information on the design of the Separations Building demonstrating it will remain intact during and'after the design basis natural phenomena (reference-LES l
letters to the NRC dated June 26, 1991, and March 31, 1992).
The Separations Building-is a System Class II structure and is designed and built in accordance with the Quality Assurance (QA)
Level 2 program requirements detailed in SAR section 10.19.
The gaseous effluent stacks are also System Class II structures l
l l
Attachment A A-2 l
l 3
-designed.and; built in accordance:with'_the QA Level 2iprogram.
The analyses ~provided in SAR sr 4 ton =2.1.2 demonstrate there.are~
no nearby, industrial', transpoetationinor military activities
.that could effect the autoclave instrumentation.
The System Class I autoclave' instrumentation is-also designedLto ensure.no-interaction between System Class II structures, systems or components (ssC)lcan initiate a failure of1the system Class.I-instrumentation.
This: includes analyses-that demonstrate that failures 1of-System Class II 880, whether process related or o
related by physical configuration,'can not resultgin failure of the System Class I~ autoclave instrumentation.-'To-fully analyss_
the physical configucation. interaction between-the_ System Class I and II SSC, the finalfplacement of all~equipmentfin the-area of.
the autoclaves must be performed..This is not done until construction is nearly. complete, to allowfforLfield' routing of-support systems (e.g., piping,. cables, lighting).-
Once all equipment is in_ place a final analysis occurs demonstrating that no adverso interaction is possible.
In summary, the System-Class-I instruments listed in SAR Table
~
4.6-1 are able to function during all' postulated normal,~ expected abnormal, and accident. conditions.
Prior to. commencement of-enrichment at the facility, the detailed interaction analyses
~
i explained in the-above paragraph will be completed and available.
for NRC review.-
F l,
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s 1
c Attachment'A A-3
- t-a 1
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1 2.
Provide analyses demonstrating that failure of Class II components (e.g., separations building, stacks, autoclaves, piping, instrument air and electrical supplies, equipment supports, etc.) does not :oduce the functioning of Class I components.
Response
LES has submitted detailed information on the design of the Separations Building demonstrating it will remain intact during and after the design basis nstural phenomena (reference LES letters to the NRC dated June 26, 1991, and March 31, 1992).
The separations Duilding is a system Class II structure and is designed and built in accordance with the Quality Assurance (QA)
Level 2 program requirements detailed in BAR section 10.19.
The gaseous affluent stacks are also System Class II structures designed and built in accordance with the QA Level 2 program.
The analyses provided in SAR section 2.1.2 demonstrate there are no nearby, industrial, transportation nor military activitios that could effect the autoclave instrumentation.
The System Class I autoclave instrumentation is also designed to ensure no interaction between System Class II structures, systems or components (88C) can initiate a failure of the system Class I instrumentation.
This includes analyses that demonstrate that failures of system Class II SBC, whether process related or related by physical configuration, can not result in failure of the autoclave instrumentation.
The System Class I instrumentation is designed in accordance with the criteria detailed in BAR section 6.4.10 (e.g., protection from fires,
- protection from earthquakes, adequate electrical separation, appropriate setpoints).
To fully analyze the physical configuration interaction between the System Class I and II SSC, the final placement of all equipment in-the area of the. autoclaves must be performed.
This is not done until construction is nearly complete, to allow for.
field routing of support systems (e.g., piping, cables, lighting),
once all equipment is in place a final analysis is performed demonstrating that no adverse interaction is possible.
Attachment A i
A-4 l
l r
r
44 s
3.
Provide analyses (seismic, structural, etc.) demonsurating that Class II components (e.g., separations building, stacks, autoclaves, piping, equipment supports, instrument air and electrical supplies, etc.) whose failure could interfere with the function of Class I systems do not fail under design basis conditions.
Besoonse LES has submitted detailed information on the design of the Separations Building demonstrating it will remain intact during and after the Design Basis Earthquake (reference LES letters to the NRC dated June 26, 1991, and March 31, 1992).
The Separations Duilding is a System Class II structure and is designed and built in accordance with the-Quality Assurance (QA)
Level 2 program requirements detailed in SAR section 10.19.
The gaseous effluent stacks are also System Class II structures designed and built in accordance with the QA Level 2 program.
The analyses provided in SAR section 2.1.2 demonstrate there are no nearby, industrial, transportation nor military activities that could effect the autoclave instrumentation.
The System Class I autoclave instrumentation'is also designed to ensure no interaction between System Class II structures, systems or components (BBC) can initiate a failure of the System Class I instrumentation.
This includes analyses that demonstrate that failures of System Class II SSC, whether process related or related by physical configuration,-can not result in failure of the autoclave instrumentation.
The System _ Class I instrumentation in designed in accordance with the criteria detailed in BAR section 6.4.10 (e.g., protection from fires, protection from earthquahes, adequate electrical separation, appropriate setpcints).
To fully analyza the physical configuration interaction between the System Class I and II SSC, the final. placement of all equipment in the area of the autoclaves must be performed.
This is not done until construction is nearly complete, to allow for field routing of support systems (e.g., piping, cables, lighting).
Once all equipment is in place a final analysis is performed demonstrating that no adverse internation is possible.
Attachment A A-5
4.
Provide a structural analysis demonstrating that cylinders, autoclaves, piping and desublimers and connectors used in these systems maintain confinement at expected operating conditions.
Present numerical results with an estimate of margin to failure.
Besponse:
The design requirements (e.g., design pressures, design temperatures) for the UF6 systems are provided in Tables 4.3-1 through 4.3-19.
All equipment has been sized and selectod to meet or exceed the listed design requirements.
For example, UF6 process piping is specified in accordance with B31.3 - 1987.
Vessels and tanks are specified in accordance with appropriate ASME,-AWWA or NFPA codes.
Detailed information regarding normal operating conditions is provided in BAR section 6.3.
To ensure conservatism when analyzing the effects of possible abnormal operations and accidents, structures, systems and components (SSC) were assumed to fail unless specific initiating event design criteria were established for the SSC.
For example, the Separations Building was designed specifically to resist the forces from natural phenomena (i.e., high winds, earthquakes, floods).
Therefore, for accident analysis purposes, an earthquake does initiate failure of the separations Building.
However, for accident analysis purposes, SSC like the autoclaves, UF6 cylinders, desublimers were allowed to fail.
The failure of all major UF6 equipment was assumed during the accident analysis for the CEC.
This analysis included:
Failure of centrifuge containment, Failure of desublimer pipe, o
Failure of UF6 positive pressure pipe, Opening a contaminated autoclave (i.e.,
failure of autoclave e
door interlock logic protection),
Failure of a UF6 cylinder, o
Failure of UF6 negative (subatmospheric) pressure pipe, o
Failure of a chemical trap, o
Fire in Separations Building, o
e Autoclave overheating and subsequent failure of UF6 cylinder and autoclave, Criticality event, and e
Protection against natural phenomena.
e During thu analysis no credit was taken for equipment to contain UF6 releases.
For example, since the Separations Building was not designed to act as a containment vessel, no credit was taken for containment of a UF6 release by the Separations Building.
Attachment A A-6
n 5.
Provide a diecussion explaining why the components of. class II systems whose function is required to protect Class I systems (e.g.,
the separations building, stacks, autoclaves, etc.) are not subject to the quality assurance requirements applied to Class I systems.
Response
The function of the separations Building is to provide protection-against natural phenomena only - it has no function related to Class I systems and no credit is taken for the building providing any secondary containment function.
It is designed to withstand various external events such as the design basis flood, earthquake, and tornado.
The function of the autoclave is to provide secondary containment of UF in the event of a breach of the primary containment.- It 6
has no function related to Class I systems.
The autoclave and its associated Class I instrumentation is designed to withstand various external events such as the design basis flood, earthquake, and tornado.
The function of the stacks are to channel all gaseous discharges past air monitoring and sampling systems and release those gases at an appropriate height for dispersion.
The stacks have no function related to Class I systems.
The stacks are designed to withstand various external events such as the design-basis earthquake, tornado, and flood.
The components of Class II systems whose passive function (i.e.,
maintain support) is required to protect Class I systems are subject to the Quality Assurance-(QA). Level 2 requirements detailed in BAR section 10.19.
The QA Level 2 program requires, among other things, that personnel performing activities are qualified, work activities (e.g.,' design, construction, maintenance) are performed in accerdance with written procedures, and design shall be defined, controlled, and verified.
This provides reasonable assurance that these BBC will fuaction as assumed in the accident analysis process described in detail in BAR sections 9.0, 9.1 and 9.2.
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Attachment A A-7 1
4 I
4.6 Classification of Structures. S y s t g.m s, and Components As discussed in our meeting of October 20, 1992, the issue of completeness of the LES analysis for identification of structures, systems, and compo.2ents important to safety remains open, pending submission of additional information.
In this subject' area, you need to fully address the three questions of our November 7, 1991, and the two questions of our May 20, 1992, requests for additional information.
Your presentation, at our last meeting of October 20th, of a suitable logic diagram for the process is a stop in the right direction.
But, you must also include in your analysis the details of the dispersion modeling and the steps in the scenario development.
We have yet to see the analysis supporting the position that relatively small releases of UFg do not lead to exposures in excess of the NUREG-1391 guidelines.
The nature of the dispersion modeling that you used in this analysis is not clear.
Furthermore, the use of TRIAD for such analysis would need technical support.
In addition, you need to document the development of administration procedures for mitigation of selected scenarios identified in the analysis procedure, for example, limiting fuel in transporters.
We would require formal commitment to the administrative procedures.
Responset The details of the accident analysis performed, assumptions used (i.e.,
steps in the scenario development and inputs into dispersion modeling) for dispersion modeling and results of the modeling are presented in detail in SAR sections 9.1-and 9.2.
In order to fully address the concerns raised at the NRC-LES meeting on October 20, 1992 and the RAI in your letters of November 7, 1991, and May 20, 1992, those specific RAI are repeated below and responses are provided.
The responses include a complete description of the methodology and steps of the accident analysis, and determination of system Class.
To ensure that fuel in cylinder transporters is limited, the proposed license conditions submitted by LES by letter dated June 30, 1992 included license condition 6.0 A.6.
This license condition requires that "only designated vehicles shall be allowed in the UF6 storage yards."
This license condition is intended to require that the vehicles are specifically reviewed to ensure the fuel in the vehicles does not pose an undue safety risk.
The transporters are designed to use diesel fuel. If necessary, the license condition can be expanded to require this review and/or design feature explicitly.
It should be noted (as stated in SAR section 9.2.2.3.1}
that Attachment A A-8 I
t 4
other factors-contribute to preventing or mitigating a potential fire in the UF6 cylinder storage areas.
No combustibles are allowed to be stored in cylinder storage areas.
Also, exterior fire protection is provided for the cylinder storage areas as described in SAR section 6.4.5.3.
The fire protection system includes redundant and diverse (1 electrically powered, 1 diesel powered) 100 percent capacity pumps, and two 100 percent capacity fJre water tanks.
The system provides adequate water supply from twa directions.
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i Attachment A A-9 i
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November 7, 1991 RAI 4.6 Summary of Structures. Components, and Systems Criteria 1.
The description of the method for identification of structures, systems and componehts important to safety presented in SAR Section 4.6 indicates that only events were considered.
Provide support for involving liquid UFg this approach by discussing release scenarios involving sublimation of solid UF from cylinders stored outside the g
separations building and from cylinders and desublimers inside the building.
Drops, punctures, and earthquake should be among the accident initiators considered.
Identify the extent of potential containment damage, release rates of UF duration of the event, and dispersion g
parameters (ground level and elevated) used to project consequences.
In the initial review of possible scenarios in which UF6 could be released from UF6 cylinders and/or plant systems, events involving both liquid and solid UF6 were considered.
A review of the physical characteristics of UP6 and NUREG-1140 "A Regulatory Analysis on Emergency Preparedness for Fuel Cycle and Other Radioactive Material Licensees" indicated the most appropriate source term to be used for accident analysis is a heated 14-ton l
cylinder of UF6 (see NUREG-1140, section 2.2.3.2).
This is the same accident source term used for conversion plants and in this regard, uranium enrichment plants are similar to conversion j
plants (see NUREG-1140, section 2.2.4).
An accident involving a cylirder of solid UF6 does not release l
enough UF6 and its hydrolysis reaction products - UO F and HF to 2 2 even approach the accident limits in NUREG 1391. 'BNFL has performed _a calculation-of release of UF6 through a 20 square mm hole (calculation enclosed).
The release rate of:UF6 for a cylinder at 20*C is 0.936 grcms per second.
The release rate of UF6 for a cylinder at 56*C is 2.3 grams per second.
Assuming a release of 30 minutes, this would result in a total release of from 1.7 to 4.1 kg of UF6.
Applying the ratio of 4.1 kg UF6 release to the 9500 kg UF6 release considered in NUREG-1140, section 2.2.3.3, would result in the following maximum exposures:
Uranium -
4.1/9500 = exposure /110 (from NUREG-1140, p. 37) l exposure = 0.05 mg uranium-Attachment A l
A-10
This is well below the 10 mg uranium " limit" specified in NUREG-1391.
Hydrogen Fluoride (HF) 4.1/9500 = exposure /160 (from NUREG-1140, p. 37) 3 exposure = 0.07 mg/m HF 3
This is well below the 25 mg/m HF " limit" specified in NUREG-1391 for a 30 minute release.
This demonstrates that UF6 releases from cylinders or other equipment containing solid UF6 are of no consequence to persons off-site.
As indicated on page 35 of NUREG-1140, "[T]he most important parameter for determining the release is the temperature of the
[UF6] cylinder."
As shown above, releases of UF6 are significant only if the UF6 is in the liquid state.
To determine the amount of'UF6 that must be released in order to exceed the limits determined by the NRC to cause significant effects to persons offsite, the information in NUREG-1140 was used to "back-1 calculate" the amount.
This determination is outlined below:
Before the publication of draft NUREG-1391, the upper " limit" for' uranium exposure was 40 mg (reference ANPR, Regulation of Uranium Enrichment Facilities, 53 FR 13276, April 22, 1988).
Applying a.
similar ratio as above:
Uranium -
UF6 release quantity /9500 = 40/110 (from NUREG-1140, p. 37)
UF6 release quantity = 3455 kg UF6 NUREG-1391 was issued in February 1991 and the " limit" for uranium exposure was established at 10 mg uranium.
Applying a similar ratio as above:
UF6 release quantity /9500 = 10/110 (from NUREG-1140, p. 37)
UF6 release quantity = 864 kg UF6 Attachment A A-11.
p Hydrogen Fluoride (HF) -
UF6 release quantity /9500 = 25/160_(from NUREG-1140, p.137) release quantity = 1484 kg UF6 Therefore, there is the potential to affect persons off-site-Lif a.
release of approximately 864 kg or more of liquid UF6'can realistically occur.
As discussed in the response to question 2:
below, this-information was used to determine the-classification (i.e.,-System Class I-vs. System Class II).for facility structures, systems and components.
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Attachment A A-12 l
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2.
The method used for identification of structures, syscems and components important to safety with respect to public health and safety should identify quantities of material at risk which if released at ground level or at stack height would result in exceedance of NUREG-1391 guidance.
This step of the analysis procedure does not rely on mechanistic identification of scenarios but is a screening tool' which identifies parts of the facility requiring closer examination.
If done using the dispersion-estimation methods of Regulatory Guide 1.145, this analysis identifies 200 kg and 4200 kg as the quantities of concern for ground level and elevated releases, respectively.
The quantities of material of concern should be combined with single failure and common cause initiated scenarias to provide more detailed analysis of those system ccmponents which could potentially contribute to exceedance of NUREG-1391 guidance.
For example, could a design basis earthquake which damaged Class II equipment, such as autoclave supports, autoclaves, or feed and produce desublimers or an out-of-doors drop of a feed or tails cylinder, cause exceedance of NUREG-1391 guidance?
Using the 864 kg liquid UF6 amount as determined as discussed above in the response to question 1, an analysis of facility structures, systems and components (SSC) was performed.
This analysis is provided in Chapter 9 of the Safety Analysis Report.
The analysis reviewed the possible effects of the following:
Failure of centrifuge containment, Failure of desublimer pipe, o
Failure of UF6 positive pressure pipe, e
Opening a contaminated autoclave (i.e.,
failure of autoclave e
door interlock logic protection),
Failure of a UF6 cylinder, e
Failure of UF6 negative (subatmospheric) pressure pipe, o
- Failure of a chemical trap, Fire in Separations Building, e
Autoclave overheating and subsequent failure of UF6 cylinder e
and autoclave, criticality event, and e
Protection against natural phenomena.
This included review e
of possible floods, high winds (tornadoes), and earthquakes.
All of the events analyzed, except for the autoclave overheating event, involve solid UF6.
Because the UF6 must be liquid form when released in order to exceed the NUREG-1391 limits, none of i
the other events (as discussed in the following paragraphs) have I
the possibility of resulting in releases of UF6 which can exceed the NUREG-1391 limits.
l-Attachment A A-13 l
L
}
To ensure conservatism when analyzing the effects of possible abnormtl operations and accidents, structures, systems and components (88C) were assumed to fail-unless specific initiating event design criteria were established for the SSC.
For example, the Separations Building was designed specifically to resist the forces from natural phenomena (i.e., high winds, earthquakes, floods).
Therefore, for accident analysis purposes, an earthquake does initiate failure of the Separations Building.
However, for accident analysis purposes, BBC like the autoclaves, UF6 cylinders, desublimers aere allowed to fail.
The failure of all major UF6 equipment was assumed during the accident analysis for the CEC.
To complete each analysis, the events, either human errors or equipment failures, that must occur to release UF6 were determined.
This sometimes resulted in conclusions, that the described event was highly unlikely and therefore no release of UF6 was probable.
The analyses demonstrated that the only possible release of liquid UF6 in excess of the 864 kg could come from a cylinder of UF6 heated in an autoclave.
This is diccussed in detail in BAR section 9.2.2.2.
The other possible abnormal events are analyzed and discussed in the BAR sections as shown below:
centrifuge Containment Failure - Described in BAR section 9.1.1 In one plant unit there is only approximately 150 kg UF6.
Therefore, since this quantity is below the 864 kg amount, even if all the UF6 was released at once, it would not exceed the NUREG-1391 limits.
This scenario conservatively assumes the following:
}
The cascade piping fails in such a way as to release e
the entire inventory of UF6. This is extremely unlikely.
Instrumentation and equipment that is QA Level 2 that is designed to detect expected process upsets and evacuate the centrifuges (cascades), fails to operate (normal extraction route).
Instrumentation and equipment that is QA Level 2 that e
is designed to detect expected process upsots and evacuate the centrifuges (cascades), fails to operate (contingency dump).
.DesublimO Pipe Rupture - Described in BAR section 9.1.2 Attachment A A-14 I
4 l
i In each plant unit, there are four desublimers (three product desublimers and one feed purification desubliner).
In addition there is one product blending desublimer located in the Blending Area of the separations Building.
The basic element of construction in each desublimer is a atainless steel pipe 16.0 inches in internal diameter and 17.5 feat in length.
Two copper tubes are coiled around the outside diameter ct the desublinor pipe.
One copper tube circulates cold Freon h11 and the cther circulates hot Freon R11 during desublimation and sublimation operations, respectively.
Each of the feed purification desublimers contains four of these pipes.
Each of the product and product blending desublimers contains only one of these pipes.
In each of the desublimers, the stainless steel pipe (s) is enclosed within a gas-tight stainless steel casing.
The casing is thermally insulated with rigid polyurethane fram and a non-rigid fill such as rock wool.
The casing is blanketed with dry nitrogen from the Nitrogen System to prevent the intrusion of atmospheric moisture.
The amount of UF6 collected in a desublimer is determined by monitoring the duration of venting operations and the weight of the donor cylinder.
Each desublimer pipe has a maximum capacity of approximately 8500 lbs UF6 at the -94 F desublimation temperature.
The operational fill limit is approximately 1100 lbs UF6 or 13 percent of the maximum capacity.
In normal operation, a desublimer pipe is emptied when its UF6 capacity is approximately one fifth the operational fill limit (approximately 220 lba).
The filling to this operational limit takes approximately two weeks and it is checked each time desublimer operations take place.
The UF6 is not allowed to liquefy or reach a pressu.;e above atmospheric at any time during the sublimation operation.
Therefore, even in the unlikely case of release of UF6 from a desublimer, the most that could be reasonably be expected to be available for rele se would be approximately 100 kilograms solid UF6.
Since this quantity is below the 864 kg amount and in the solid form, even if all the UF6 was released at once, it would not exceed the NUREG-1391 limits.
An additional scenario involving desublimera was analyzed and is detailed in BAR section 9.1.2.
This scenario involves the rupture of an overfilled desublimer.
The analysis concludes that because multiple faults must occur cver a very long period of time (i.e., weeks), by different people, while several Quality Level 2 instruments fhil simultaneously, the event is not credible.
Attachment A A-15 l
UF6 Positive Pressure Piping Failure - Discussed in BAR section 9.1.3 Analysis of UF6 positive pressure piping failure assumes a pigtail break due to metal fatigue or a faulty weld, valve, or flange connection.
It also assumes the operators fail to follow procedures required to check the integrity of the piping after connections are made to UF6 cylinders.
Although defective piping could fail during normal procers oporations, this is very unlikely because of the absence of vibration, the relatively low operating pressures, and the use of corrosion resistant materials.
In any event, the UF6 is contained within the autoclave.
Therefore, no release of UF6 occurs.
Erroneousiv Openinc a Contaminated Autoclave - Described in SAR section 9.1.4 The most likely cause of this event would be operator error during the verification of and response to
- release of UF6 inside an autoclave.
The autoclave design includes several layers of design features to alert operators to the presence of contamination.
Additional design features decrease the probability of operator errors associated with erroneous autoclave door operation.
These design features are as follows:
Redundant System Class I air pressure sensors would e
l detect the increase in air pressure associated with a large leak of UF6 inside an autoclave.
A visual and audible alarm inside the Central Control Room would alert operators to the potential for contamination l
within a specific-autoclave and shut down the heaters within the autoclave.
A small leak would bo detected l
by the increase in the pressure / temperature ratio l
within the autoclave.
The autoclave door is interlocked trith an air pressure e
sensor to prevent the door from opening until the autoclave air pressure is equal to or less than atmospheric pressure.
Also, the autoclave vent valve must be opened befora the automatic door lock would i
release.
l l
The valve to the Gaseous Effluent Vent System e
physically restricts autoclave door operation until it is moved to the open position.
Therefore, it must be Attachment A A-16
open before the autoclave door could be opened.
Plant operating procedures require that the valve to the Gaseous Effluent Vent System remain open longer than the HF detector's response time.
The presence of HF would be detected by the HF detecto-in the Gaseous Effluent Vent System, alerting plant operators to the presence of contamination in the autoclave.
- In the event of a suspected UF6 release within an autoclave, the operating procedures will mandate that following the heater trip no further action is taken until the autoclave contents have cooled and solidified.
Consequently, even if the above means of detection are assumed to fail, the release would be very small, because the UF6 would be in solid form.
Cylindsr Rupture due to UF6 Reactions - Described in BAR section 9.1.5 1 There are two postulated ways for reactive material to enter a UF6 cylinder.
One way is for a reactant to be introduced into a cylinder through the UF6 piping.
Another way is for a reactive impurity to be present in a supposedly clean, empty cylinder when it is received.
Water reacts too quickly with UF6 to ever enter a cylinder f
as a process impurity.
Free liquid water cannot exist at UFG process pressures.
Any residual moisture would quickly react with UF6, causing a process shutdown.
It is conceivable, however, for hydrocarbons to be accidentally introduced into a cylinder containing UF6.
In the CEC, hydrocarbons and other reactive substances are not used where leakage into a UF6 system is possible.
A chemical reaction would be possible only if hydrocarbon oil was unintentionally substituted for Fomblin oil, an inert substance.
The only credible scenario for in-leakage begins with the substitution of a hydrocarbon oil for the inert Fomblin oil used in process vacuum pumps.
Two simultaneous, major operating errors would have to occur for a hydrocarbon to be substituted for Fomblin oil.
First, a hydrocarbon lubricating oil would-have to be introduced into the storage area for the Fomblin oil used in all process vacuum pumps.
This would be a violation of material handling procedures.
Second, the maintonance technician would have to mictakenly fill a process vacuum pump with the hydrocarbon oil, despite its different appearance and density.
This would be a Attachment A A-17 l
Violation of maintenance procedures.
Pumps that use Fomblin oil are maintained in a separate area of the pump workshop.
Having installed an incorrectly filled pump into the plant, there is still no reason why the oil would travel t u
cylinder.
In the case of the low and high pressure UF6 pumps, where the oil is exposed to process gas, these pumps would rapidly fail on overload.
In the case of the de3ublimer vent pumps the oil will not be rapidly degraded as only traces of uranium are expected to reach the pump.
For the oil to travel to a cylinder, the pump non-return valve and the pump inlet valve would have to fail to allow the oil initially into the piping local to the pump.
The likel! hood of this oil reaching a take-off cylinder is equally as remote as that of the low and high pressure UF6 pump oil.
Empty cylinders are received only from suppliers that follow the procedures of ANSI N14.1 - Packaging of Uranium Hexafluoride for Transport for all cylinders.
ANSI N14.1 specifies that new cylinders be cleaned, degreased, thoroughly dried, inspected internally, and plugged.
Although cylinder suppliers are required to meet these specifications, cylinders must undergo thorough inspection procedures upon arrival at the CEC.
To check for the presence of reactive materials, empty cylinders are weighed for discrepancies with the cylinder supplier's data upon receipt at the CEC.
The weighed cylinder is then inspected internally with a boroscope to check for grease or other material.
If the cylinder is clean, an inspected superior valve is installed.
The cylinder is then vacuum tested to see if any volatile impurity is present.
The test is performed with a vacuum pump lubricated with Fomblin oil.
The vacuum pump has a suction reservoir and oil traps to prevent the back-flow of pump oil into the cylinder.
At least 90 lbs of UF6 is required to over-pressurize a product cylinder containing sufficient hydrocarbons for a complete reaction; more would be required to over-pressurize a feed or tails cylinder.
Because of possible over-pressurization, the initial charge of UF6 at the cylinder fill station is limited to 20 lbs.
Over 100 lbs of UF6 is required to over-pressurize a product cylinder containing sufficient water for a complete reaction.
After the initial charge, the filling is stopped until the absence of chemical reaction products is verified by monitoring the cylinder for zero presst.e rise.
Attachment A A-18
Cylinder reccipt inspections ~and cylinder filling are performed in different buildings.
As a result, the procedures are independent tasks.
The following independent errors would have to occur'in order for a presumed clean cylinder to be over-pressurized a.
On arrival, the cylinder contains enough reactive impurities to potentially over-pressurize it.
b.
The visual examination is performed incorrectly or omitted.
c.
Either the vacuum test is performed incorrectly or the reactive impurity is non-volatile.
d.
Too much UF6 is added initially or the operators-somehow continue filling after recording high pressure and temperature indications, in violation of procedures.
It is highly unlikely for more than two of the above events to occur independently while inspecting the same cylinder.
Therefore, this incident is highly unlikely and no release of UF6 is assumed.
Hydraulic Rupture of UF6 Low Pressure Pipinc - Described in SAR section - 9.1.6.
The only potential cause of a low pressure UF6 pipe rupture is a heat tracing and/or hot box failure that allows UF6 to desublime inside the pipe, and subsequent operator error which allows the pipe to be reheated before the solid UF6 is evacuated.
The following sequence of faults must occur before a release of UF6-is possible:
a)
Failure of the heat tracing and/or hot box heater circuit, or loss of primary and standby power supply to the heaters, or operator error-that erroneously de-energizes heaters, b)
Failure of the temperature sensor and/or alarm in the heater circuit that controls temperature.
This is independent of the above failure because the heater and sensors receive power from differeat sources.
L c)
Failure of the temperature sensor and/or alarm in L
the independent protection circuit.
Attachment A A-19 i
l l
l l.
d)
Failure of the pressure and/or flow instrumentation to alarm in response to changes in these parameters associated with the formation of a flow restricting plug.
Note that this failure does not apply to lines in which there is no flow such as isolated branch connections.
The above failures would allow UF6 to desublime in the pipe or component.
At least three independent failures must occur to form a plug due to UF6 desublimation.
In addition, the following events must occur before liquefaction of UF6 could rupture the pipe:
e)
The operator erroneously re-energizes the heat tracing and/or hot box heater before evacuating the desublimed UF6.
The operator could also fail to de-energize an inadvertent restoration of power before evacuating the desublimed UF6.
Note that this fault is not necessarily independent of (a),
(b), and (c) above because the operator would not be aware of the potential for a problem if the alarms failed.
Chemical Trap Runture - Described in_SAR_soction 9.1.7 The potential hazard with respect to a chemical trap rupture is for uncontrolled UF6 flow into the activated charcoal / alumina traps downstream of the desublimers.
Either (i) the desublimer is in a cold venting state, and hot freon erroneously flows around the desublimer, or (ii) the desublimer is in a hot pressurized state,
.nd UF6 backflow through the desublimer discharge valve occurs.
In the former case the potential is for the desublimer vent pump to pull large quantities of UF6 through the chemical traps.
In the latter case the potential is for large quantities of UF6 to pass through the desublimer outlet valve into the chemical traps.
Under these conditions, the adsorption of UF6 on the activated carbon bed of the chemical trap would cause the4 temperature of the bed to rise sharply over a period of several minutes, evolving several pounds of cerbon monoxide.
The sharp temperature rise in the chemical trap would exceed its design temperature and cause it to expand, which could in turn cause it to fail mechanically.
Thus, air in-leakage is assumed to occur which could produce an explosive mixture of CO and oxygen.
This mixture is assumed to ignite due to Attachment A A-20
+
l
either a static spark in the bed, a spark from the vacuum puup, or auto-ignition.
The possibility of the desublimer vent pump pulling on a hot desublimer is precluded by the following:
a) the desublimer logic precludes this.
b) the hot freon supply valve fails closed making the possibility of incorrect freon flow due to valve failures remote.
c)
A flow switch on the hot freon line prevents access to a desublimer vent state, if the hot freon is flowing.
d)
A temperature trip on the desublimer body prevents access to a desublimer vent state unless the desublimer is chilled.
Since at least two unlikely, independent failures must occur, the explosive rupture of a chemical trap is not credible during the on-line,. standby, or purification modes of operation.
Note that the vent vacuum pump normally operatos during the on-line, standby, and purification modes evaluated above.
During the heat and gas-over modes (hot freon modes), the vacuum vent pump does not operate.
Therefore, if the desublimer outlet valve fails open (unlikely; fail closed valve), very little UF6 would transfer from the desublimer to the chemical trap because the pressure in the desublimer and the chemical trap would equalize.
The reaction would be self-limiting because the generation of heat within the chemical trap would establish a temperature gradient.
If the chemical trap failed mechanically due to the temperature rise, very little air could enter the trap before the closed volume within the desublimer and chemical trap reached atmospheric pressure.
Therefore, there are no credible circumstances by which an explosive mixture could be formed within a chemical trap during the heat and gas-over modes of operation.
Even if this unlikely event were to occur, the chemical traps would contain a maximum of approximately 28 kilograms of solid UF6.
Fire in Separations Building - Described in SAR section 9.1.8 An evaluation was performed to determine the fire hazards in the CEC.
The Technical Service Area in the Separations Building, the diesel fuel storage area, and areas in which Attachment A A-21
i transformers are located were determined to have the greatest potential = fire hazards.
Fire hazard assessments were based on anticipated inventories of combustible materials and their proximity to the Cascade Halls and UF6 Handling Areas.
This evaluation demonstrates that postulated fires in the most likely locations would not damage safety class equipment and would not contribute to the release of UF6.
Separate calculations were performed to determine maximum fire duration in each room or area designated above.
Estimated inventories of combustible material included both stationary and transient combustible materials.
The calculations for the equivalent fire severity were based on methodology given in the NTPA Fire Protection Handbook.
The u
calculated fire durations for each room and area assumed total failure of the Fire Protection B;' stem and no response from the fire brigade.
The calculations conclude that none of these worst case fires could penetrate fire barriers or spread to areas in which UF6 is processed.
The calculations for maximum fire durations assumed no fire o
suppression or brigade response.
Therefore, the combustible material in each room or area would be consumed and some equipment would be destroyed in the postulated fires.
The calculations demonstrate that the fire-rated barriers would contain the postulated worst case fires assuming all combustible material is consumed.
Therefore, postulated fires in the most hazardous locations would not damage safety class equipment and would not contribute to the release of UF6.
The only potential release of radioactive materials would occur as a result of a fire consuming spent HEPA filters or contaminated solid waste.
Small quantities of radioactive materials would be released to the building with only trace quantities released to the atmosphere.
Possible Accidents Resultina From Natural Phenomena - Described in BAR section 9.2.12 The Separations Building is designed to withstand the following natural phenomena: Earthquake, Tornado, Hurricate, and Flood.
The design bases intensities of the natural phenomena are discussed in detail in-SAR section 9.2.1.1 through 9.2.1.4.
The analysis of these events-provided in the above references sections of the SAR demonstrates that none have the possibility to cause a release of UF6.
Attachment A A-22 8
I Fire In Storace Yard - Described -in BAR section 9.2.2.3.
The cylinder storage yards are designed in conjunction with the fire protection systems to prevent fires from occurring.
Based upon the evaluation discussed in BAR section 9.2.2.3, a fire in the UF6 cylinder storage yards does not result in the release of UF6.
T.ransportation Accident The NRC and U.S.
Department of Transportation (DOT) have looked closely at postulated accidents involving cylinders transported by trucks (refer to SAR references 9.2-16, 17 and 20).
They concluded that a wreck, combined with a fire, is the transportation event which is likely to post the greatest hazard to the public.
These NRC and DOT analyses are relevant to CEC in regard to accidents involving over-the-road trucks which come onto the site.
The DOT analysis concluded that, should a truck wreck and fire occur, resulting in a breach of the cylinder, then the persons in the most serious danger would be those in the immediate vicinity of the fire (i.e., persons involved in the wreck).
Based on the analyses and tests referenced above, the NRC and DOT concluded that the public would not be endangered by truck transport of UF6 cylinders if cylinders are designed and certified per ANSI N14.1-1982, and if vehicles are properly operated.
Based on this, the NRC and DOT have licensed transport of UF6 cylinders by truck.
Accidental Criticality The LES, CEC, Criticality Safety Engineering Report, Revision 1, submitted to the NRC by LES by letter dated June 30, 1992 provides a comprehensive review of possible accidental criticalities at the CEC.
It concludes that a criticality at the CEC is highly unlikely.
Autocinye_ Heater Malfunction - Described ip 8AR section 9.2.2.2..
This accident is discuused in detail in BAR section 9.2.2.2.
It concludes, that since this is the only equipment in the facility that contains liquid UF6 in significant quantities, that the possibility exists for more than 864 kg of liquid UF6 to be released.
Therefore, two temperature and two air pressure instruments, any one of which is capable of Attachment A A-23 l
u
l tripping the autoclave heaters, have been designated System Class I and will be designed, bu,ilt and operated in accordance with the LES QA Level 1 program.
Therefore, the instruments may be assumed to function thus eliminating the possibility of release of UF6 from the autoclaves.
It should be noted that the analysis of UF6 release using the TRIAD method was performed and provided in SAR section 9.4 for information only.
The methodology used in NUREG-1140 is very conservative.
Section 2.1.5 of_NUREG-1140 lists the conservatisms associated with the modeling i
technique.
The TRIAD results provide another indication of j
possible exposures assuming worst case accident scenarios at the CEC.
The results from the TRIAD modeling were not used to make any decisions regarding the classification of SBC nor determination of the need for an emergency plan for the CEC.
i l
l l
l
\\
l.
l Attachment A A-24
4 '
- 3. SAR Section 4.6 (p 4.6-1, paragraph 3) indicates that detailed analyses of credibility and potential consequences of postulated abnornal conditions and accidents were performed.
Provide summary descriptions of these analyses of abnormal conditions and accidents and detailed descriptions of the analyses for those events with potential for significant impacts on workers or members of the public.
See response to question 2 above.
The descriptions of the analyses and abnormal conditions and accidents are provided in SAR Chapter 9.
A Attachment A A-25 l
May-20,-1992' RAI
- 4.6
SUMMARY
- OF STRUCTURES,. COMPO%dTS, AND SYSTEMS CRITERIA Question 1:
Provide a copy ^of the FDI report on identification of structurcs, components and systems important to safety.
Response
SAR section 4.6 is-the 3. sport that contains the.information regarding the 3dentification of structures, systems, and components (SSC) important to safety (i.e., safety-related)..
Since the-only credible.UF6 release scenario which'could occur at
~ '
the CEC that exposes the public to values of uranium and/or hydrogen fluoride (HF) beyond those stated in NUREG-1391.is one in which at leastione cyliador of liquified UF6 and its associated autoclave-fail simultaneously, the autoclave.
instruments for air temperature and air pressure have been designated.as safety related.
Since there are twoLinstruments for, temperature and pressure for each autoclave, this ensures a.
redundant ~and diverse. method.for preventing an accidental release.
from cylinders containing. liquid UF6.
J r
Attachment A A-26 4
~
r
+
4 Question 2:
The rosponso to this question indicatos that the threshold quantity of UFg which, if released through the stack, would exceed NUREG-1391 limits is 3700 kg.
NRC staff analysis, conducted veing the methods of Regulatory Guido-1.14S and the revised noteorological data, Jrdicatos that this threshold quantity may be as low as 1800 kg.
Tho 95 porcent over-all concentration por unit releaso factor (X/Q) was estimated as approximately 1.6 x 10~0 s/m.
Provido detailed documentation 3
supporting the proposed threshold quantity, including description of the dispersion analysis and cumulativo distribution for X/Q.
If method used in calculation of the X/O differs from that of Regulatory Guido 1.145, provido a justification for use of the alternative method.
See-response to question 1 (November 7, 1991) above.1 The results of the analysis using the NUREG-1140 methodology was that used to determine the safety related structures, systems, and components (8sc) for the facility.
SAR section 9.2, Figurou 9.2-3 and 9.2-4 provide the estimated exposures to MF and uranium with respect to-distance from the source of the release.
The figures were developed using the NUREG-1140 usthodology.
The TRIAD results were.provided for c o m p a r i s o n o n 1*f.
Specifically, CAR section 9.2.4 provides a detailed description of the atmospheric dispersion analysis used, the-exposurcs predicted by the TRIAD analyses, and the uncertaintier associated with the analyses.
p 4
Attachment A A-27 l
October 29, 1992 6.4.10 control System This issue romains opon pending submission of additional information discussed during our Octobor 20 mooting.
Primarily, we nood technical support for our ovaluation e.f the functicn of Class I systems (question 2, of our November 7, 1991, letter).
As indicated in the specific questions prosanted below, the primary technical issue requiring clarification is the review of the logic for implomontation of the Class I function.
l Specific Clarifying Questions for Instruments and controls:
1.
The logic diagram of Figure 6.4-40 appears to indicate that the combinations of signals from PE-115 with TE-122 and of PE-118 with TE-127 do-onorgit o the heators along indopondant paths.
The Machanical Flow Diagrams for tho Food Autoclavo System show the signals from TE-122 and TE-127 ontoring a common logic unit and the signals from PE-115 and PE-188 ontering another commen logic unxt.
Resolve the apparent inconsistency.
BeRROAset Pigure 6.4-40 has been revised to indicate more clearly the signal combinations that satisfy the logic that de-energizes the autoclave heaters and to ensure consistency with the Feed Autoclave Mechanical Flow Diagram (BAR Figure 6.8-1).
A copy of revised SAR Figure 6.4-40 is enclosed and will be added to the Safety Analysis Report (BAR).
As shown on the revised figure there is no reliance upon Class II autoclave heater interlocks to de-energize the autoclave heater contacts in the event of high autoclave pressure or high autoclave air temperature.
Attachment A A-28
--h---
~
o
- 2.
Figure 6.4-40 appears to Jr.ncate that Class II autoclave heator interlocks must be functional to du-onorgize tho autoclave heator contacts.
Is this a correct into:.protation of this-design?
If not, clarity the proposed function.
If so, provido a rationale for making the function of a class 1 system dopondent upon tha function of a Class II system.
Identify the-interlocks in question.
EngsAnAl Figure 6.4-40 has been revised to indicate more clearly."ly
]
signal 1 combinations that satisfy _the logic that de-energr*-'f; the
.i autoclave heaters..A_ copy of revised SAR Figure 6.4-40 is enclosed and will be added to the Safety Analysis Report (SAh)-
1' As shown on the revised figure there is no reliance upon class II autoclave heater interlocks to de-energise _the autoclave heater contacts in the event-of_high autoclave _ pressure or high autoclave air temperature.
q h
b i
f f
r Attachment A A-29
- r
. ~,, -. - -,,
y---,
,m,,
.y-,.=
,m---,
i 3.
Aro the control circuics PE-112/PI-112 (trip heators on high i
cylinder pressuro), PT-113/PI-113 (isolato cylinder on high autoclavo oxit lino pressure), and PT-502/PI-502 or PT-503/PI-503 (isolato plant unit food hoador) active in the oight autoclavo statos?
Ruanans.el The PE-112/PI-112 pressure trip system referred to is that associated with the pressure side of the (process gas / autoclave air temperature) cascaded controller, which controls the autoclave air heaters.
The cascaded controller comprises the contrvi elements of the PE-111/PI-111 & TE-121/TI-121 transducers, see BAR Fig 6.8-1.
The control function is not required in the two autoclave states ISOLATE and COLD PURIFY and is consequently inhibited in these states (reference Control and Logic Descriptions - LES letter to NRC dated March 24, 1992).
The control function is activated in the remaining six autoclave states.
The PE-112/PI-112 trip function (which trips the air heaters and fan at 44 pcia) is similarly only functionally required in the same six states, noted above, when the heaters are activated.
In the interests of circuit simplification, and because there is no operalsanal disadvantage, the PE-112/PI-112 trip function is left activated in all eight autoclave states.
The PT-113/PI-113 pressure trip system referred to is that associated with the control function of the PT-114/PIC-114 pressure system.
This system is-located on the sub-atmospheric process gas pipe outside the autoclave.
The PT-114/PIC-114 control function modulates the process gas let-down valve HV-134 located within the autoclave.
This control function is only activated in the statos HOT PURIFY and HEELS REMOVAL of the autoclave state switch.
The trip function of PT-113/PI-113 (at approximately 1.16 psia) is to isolate the feed flow from the autoclave if the process gas l
pressure erroneously approaches ambient condensation pressure.
l This will always be a valid trip. function and consequently, unlike the control function, it will always be active in all eight autoclave states (reference Control and Logic Descriptions - LES letter to NRC dated March 24, 1992).
Attachment A l
A-30 l
.... _ _ -. ~ _ _ _.
4 a
The pressure trip transducers PT-502/PI-502 and PT-503/PI-503 referred to are those associated with the PT-501/PIC-501 control and trip pressure transducer on the plant; unit feed distribution manifold.
The function of PT-502/PI-502 and PT-503/PI-503, to isolate the feed header on a' pressure-rise, is always valid.
Consequently the trip function of the two transducers in question is active in all eight autoclave states.
q 1
i t
I
-j v
F F
r
' Attachment A
= A-31 L
r a
+
sr.
....4
.4, r..
m,,. - _w w,,r--.
-___.4,.,,m.-.,.,,.-..
.,4 yf
?
4.
Figura 6.8-1 shows that the signal from PIC-111 to the heater logic control until is routed through TIC-121?
What role does autoclava temperatura play in this control loop?
Renoonse:
The 4G" cylinder in the autoclave and thus its contents are heated indirectly via air drawn over the electrical heaters.
The air temperature (measured on TE-121) is controlled using a cascaded controller (TIC-121) whose setpoint is adjusted with relation to the UF pressure within the container (measured on 6
E-111 and controlled by PIC-111).
This functions so that the temperature setpoint of controller TIC-121 is increased, within an overall maximum value, as the measured UF6 pressure falls below the PIC-111 control point and vice versa, within an overall minimum value.
Figure 1 enclosed shows the relationship between the UF pressure and air temperature control point during the 6
cor.cainer warm-up phase.
Thus, from cold, the air temperatvre will be raised to the maximum cut-off value.
This will be maintained until the measured UF pressure rises to a value which will cause the 6
temperature setpoint to reduce.
The air temperature setpoint will continue to reduce until the triple point is reached where it will remain steady.
When the UF has liquefied, the pressure 6
will contint> to rise and the temperature.setpoint will fall.
When the measured UF6 pressure reaches its control point and the container contents are in equilibrium, the temperature Citpoint will remain steady.
During the initial warm-up phase the pressure controller setpoint will be set at a value greater than that required for feeding to the pair of assay units.
This will have the effect of reducing the time taken to fully liquefy the UF.
During standby duty, 6
the controller setpoint will be reduced to its online duty control point.
UF has a high thermal inertia, more noticeable in the solid than 6
in the liquid phase.
The inertia is due to two factors.
Firstly, the poor thermal conductivity of UF causes a time lag i
6 between energy being fed into the system and its effect being l
noted, and secondly, the contents of the container represent a high thermal mass.
Liquid UF has a relatively lower thermal 6
inertia because of the convective currents which_can be generated in the liquid which will allow for a more nearly isothermal regime to obtain.
This inertia will cause an over-and under-shoot of control, which using the above control philosophy, will be rapidly attenuated even using purely proportional control.
Attachment A l
A-32 l
l
[
1
1 4
- 5.
-Provido logic diagrams, analogous to Figure 6.4-40 for all class I systems (o.g., for blonding and sampilng autoclaves).
Respons3_t SAR Figure 6.4-40 has been relabeled to indicate this logia diagram is the name for Blending and sampling, as well as Feed Autoclaves.
4 D
Attachment A A-33
6.
The nG% c : on Figure 6.8-2 refer to the autoclavo vont valvo.
Idontify the location and function of this valvo.
BesPSAsel The autoclave vent valve is valve HV-139 shown on BAR Figure 6.0-1, Frame 2 of 4, section 5.
The function of this valve in to isolate the purification header from the main UF6 supply route from the autoclaves to the cascades.
The valve is operated via ti. 9 autoclave state switch.
Attachment A A-34
.~
l 7.
Are the food autoclave valves M-136 and HV-137 closed in each of the eight autoclave states?
When are the valves i
open?
How aro they opened?
.)
Rt3Donsel i
The eight position autoclave state switch does not directly command the valves MV-136 and HV-137.
l 1
In six of the eight positions of the autoclave state switch (HEAT f
UP, HOT PURIFY, MANUAL STANDBY, AUTO STANDBY, ON LINE and HEELS l
REMOVAL) the autoclave heaters are energized.
A series of.
interlocks ensures that in all of these state switch positions i
the valves MV-136 and HV-137 are CLOSED.
s These interlocks aret HV-137 NOT CLOSED Inhibits air heaters.
NOT OPEN Inhibits autoclave door from being unlocked.
HV 136 NOT CLOSED Inhibits air heaters.
-- i NOT OPEN A mechanical interlock prevents the autoclave door from being opened.
Autoclave DIFFERENTIAL Inhibits HV-137 from differential PRESSURE NOT being opened.
Inhibits air pressure 2 FRO autoclave door from being unlocked.
Autoclave door NOT CLOSED Inhibits air heaters.
1 NOT OPEN Removes' inhibit on air heaters.
t Attachment-A A-35 m
a em-
,me,.w
--w
--n-a
~
~
~
e
..w-
?
Autoclave door NOT LOCKED Inhibits air heaters.
lock LOCKED Removes inhibit on air heaters.
State Switch HEAT UP Removes heater inhibit HOT PURIFY Removes heater inhibit MANUAL STANDBY Removes heater inhibit AUTO STANDBY Removes heater inhibit ON LINE Removes heater inhibit HEELS REMOVAL Removes heater inhibit State Switch ISOLATE Inhibits air heaters COLD PURIFY Inhibits air heaters Following feed heels removal the autoclave state switch will be set to ISOLATE.
The gaseous effluent vent valve HV-136 will be opened.
The autoclave air pressure will be noted to fall and the abaence of an HF alarm in the gaseous effluent vent system will be noted.
HV-136 will be opened remotely from the autoclave local control center (LCC).
Following establishment of the above noted conditions the atmospheric vent valve HV-137 will be opened again by remote operation from the autoclave LCC.
The autoclave door will now be unlocked itnd opened.
Consequently in ISOLATE the valves HV-136 and HV-137 will be either OPEN or CLOSED as appropriate.
The cylinder will now be changed, and following installation and connection of the new cylinder, the autoclave state switch will be set to COLD PURIFY.
Cold purification is carried out with the autoclave door OPEN.
Following the completion of cold purification the autoclave is prepared for heat-up.
The door will be CLOSED and HV-136 CLOSED and the door LOCKED and HV-137 CLOSED.
Consequently in COLD PURIFY the valves HV-136 and HV-137 will be CLOSED or OPEN as appropriate.
Attachment A A-36
&g t
w
l 8.
What is the function of the control unit associated with the position of HV-131?
Bosponsql 2LH-131 is a trip taken off the limit switch on the Superior valve.
The Superior valve must be open (and other logic conditions met) before the heaters can be energized.
If at any time this valve is closed, then the heaters and fan are de-energized immediately.
The same logic holds for the hand valve (HV-133) immediately downstream of the Superior valve.
Attachment A A-37
A 9.
Can the-cylinder valve be opened or closed af ter the autoclava la closed?
RenRonses.
i
-The cylinder valve is connected to at, operating' mechan sm, the-handle of which is accessible from outside the autoclave.. Using this_ operating mechanism the cylinder valve can be closed without restriction.
If the valve is closed during one of the six autoclave states-in which the hesters are energized then.the cylinder valve switch trip 2LM-131 (SAR-Figure 6.8-1, Frame.3 of
- 4) uill cause the air heaters and fan to trip.
P i
t t
t r
Attachment.A A-38 1
r p---
.,my.-s, v v. m e e -
e*v
=
a-y-*
w
.w,-m.,
-v
- ' = - - - --' - - - -
wr=-->-
'wv
' 10.
Paragraph 3 on-SAR, page 6.3-11, indicates that the feed autoclave heaters;are de-energized when the autoclave air pressure reaches 43.5 psia.
Table 6.3-2 indicates that this cut-off pressure is 24.6 psia.
Resolve the apparent inconsistency.
.Reangnasi i
The trip.value of 43.5 psia is the trip'value for the feed cylinder UF6 pressure (see SAR~page 6.3-11,' paragraph 4)' and was inadvertently repeated in: paragraph 3 on SAR page 6.3-11.
The
-correct value for.the-air-pressure trip level,is 24.6 psia, as given in SAR Table 6.3-2.
The revised SAR page is enclosed.
l L
3
- Attachment A A-39
?
I:
l..
-.--.a n
..a
,.s
11.
What are the procedure and reference temperature and pressure for establishment of 1100 KG as the capacity of a single tube desublimer?
Responset Please Notet The capacity of the single tube desublimer, as stated on BAR page 6.3-8, is 1100 lbs (pounds) not kilograms as stated in the question.
The capacity was determined by experiment.
The desublimers were developed for the product and tails take-off systems for the Almelo and Gronau plant and had to desublime about 16 kg UF6/ hour.
The fill limit was determined by the cycle time needed for cooling down the desublimer, condensation of L'F6, heating up, evaporation of UF6 and cooling again taking into account two sets-of desublimers operating alterrately.
The reference temperatures of hot / cold refrigerant were +60/~70*C.
The reference pressure was 0.8-0.4 mbar during desublimation and less than-1000 mbar during heating.
Please note that the desublimer controls are designed so that desublimer refrigerant does not rise above 55'C.
l Attachment A A-40 l
l u
'12.
What are the set points, as weight of cylindar-contents, at which the inlet valves for the product and tails take-off stations are clcsad on over-weight signal?
Responset The setpoints are_ determined and set such that there exists a safety margin to the maximum not weight of twice the accuracy of the measuring system (i.e.,
the product take-off-station load cells WE-855 and the tails take-off station load-cells WE-865).
This is approximately 60 kg for the product take-off stations and approximately.190 kg for the tails take-off stations.
+
u Attachment A A-41
13.
Framo 2 of Figure 6.8-9 shows a UFg Hoels Transfer Lino entoring/ exiting the desublimer.
This lino is separato from the UF Discharge Lino entering / exiting the desublimor.
S Framo 1 of Figure 6.8-10 indicates that the hools transfer lino entors the rocoiver cylinder hot box but the configuration of this transfor line is not clearly shown on the hot box detailed diagram of Framo 3 of Figure 6.8-10.
Does the heels transfer occur via valvo XV-331?
What is the flow path for transfor of hools from the desublimer to the recolver cylindor?
Responsal pESUDLIMER HEELS TRANSFEB There are five receiving stations installed in the Product D1ending System.
These comprise cold Stations G-460-CD-001A through E and Hotboxes G-460-HD-003A through E shown in BAR Figure 6.8-10.
stations A through D are for receiving blending material from the autoclaves and Station E is for receiving heels material.
Heels material may be transferred into Station E from either the autoclaves or from the Diending System desublimer.
In the case of heels material being transferred from an autoclave, that autoclave will be selected to HEELS TRANSFER at the autoclave state switch.
The heels receiving station, station E,
will be selected to TRANSFER 1 or TRANSFER 2 as appropriate.
The transfer route for the autoclave heels material (for autoclave 1) vill be via HV-133, HV-134, PV-135, HV-138 along the Transfer Line 1 and then into the receiver cylinder No. 5 via HV-315.
In the case of heels mecerial being transferred from the desublimer, the desublimer will be selected to GAS-OVER at the desublimer state switch.
The heels receiving station will then be selected to VENT at the state switch for receiving station 5.
The transfer route for the desublimer heels material will be from the desublimer, through the Heels Transfer Line (the line referred to in question 13) and into the hotbox of the fifth receiving station.
Inside the hotbox for the fifth receiving station the material routes through HV-345 and into the rectiver cylinder.
It is important to note that the Heels Transfer line routes to the hotbox of the fifth receiving station only.
Heels material is only transferred into the fifth heels receiving station and Attachment A A-42 I
l noe to any other station.
The valve and pipework arrangements itiside all five receiving station hotboxes are, however, identical.
The process difference between the Dianding Receiver Stations A-D and the Heels Receiving Station E is as follows:
In the case of Stations 1-4, the process route is for material ~
being vented from the receiving station into the Discharge Line and into the desublimer.
The switch selections will be VENT add RECEIVER STATION VENT for the desublimer and receiver station.
In the case of Station 5 there are two process routes.
Either the receiver station will be receiving material from the desublimer in which case, as noted above, statn switch selections will be GAS-OVER and VENT for the desublimer and station 5, respectively.
Or station 5 will require venting to the desublimer.
It should be noted that it is not anticipated that station 5 will require venting in process as it will only receive pure heels material.
To facilitate such operations as pipework degas prior to cylinder change, however, a station 5 vent facility is aveilable.
This would be achieved by state switch selections of CHILL and VENT for the desublimer and station 5, respectively.
LOGIQ To prescribe the venting arrangement for station 5 (the heels station) a modification is necessary to the logic specifications submitted by LES by letter dated March 24, 1992.
The modified Product Blending System, Control and Logic Description is enclosed.
The modifications are highlighted on pages 8 of 14 and 12 of 14.
Specifically, the vent selection of the station 5 state switch is only enabled in GAB-OVER and CHILL selections of the desublimer state switch.
Corresponding amendments are made to these desublimer state switch positions.
Attachment A A-43
14.
Figuro 6.8-10 appears to indicato that valvo XV-331 connects the recuivor cylinder station to the mobile pump set and N2 purgo linen.
Why is valva HV-331 not closed when tha rocoivor cylindor station stato switch is in the isolato position?
ReaRone_91 Only part of the logic for the cylinder state switch is shown in NOTE 6 of FIGURE 6.8-10, FRAME 1 of 4.
The full logic is provided on page 8 of 15 of the Control and Logic Description -
Product Diending System (reference Control and Logf.c Descriptions
- LEs letter to NRC dated March 24, 1992).
There are two receiver cylinder station state switches.
FIRST SWLTCH (4 position) - Der cylinder recelyinC__s_tAtloILv.
TRAN8FER 1 CLOSED HV-321 HV-341 OPEN HV-311 TRANSFER 2 CLOSED HV-341 HV-311 OPEN HV-321 VENT CLOSED HV-311 HV-321 OPEN HV-341 ISOLATE CLOSED HV-321 HV-341 HV-311 SECQNp BWILQ11 (2 position) - Der cylinger receivina statio h OPEN OPEN HV-331 Switch only selectable to OPEN when FIRST SWITCH is selected to ISOLATE.
CLOBED CLOSED HV-331 Discussion The above logio shows that when the cylinder station is either Attachment A A-44
receiving transfer material (in states TRANSFER 1 or TRANSFER 2) or venting material (in state VENT) the " maintenance valfe" HV-l 331 is CLOSED.
When the cylinder station is not receiving material it will be set to ISOLATE.
ISOLATE is the only state selection in which the " maintenance valve" HV-331 can be opened.
If the HV-331 state switch is selected to CLOSED when the cylinder state switch is selected to ISOLATE, than all four valves HV-311, HV-321, HV-331 and HV-341 will be CLOSED.
This is the situacion, for example, when the cylinder station is=on stand-by waiting for duty.
If the HV-331 state switch is selected to OPEN when the cylinder state switch is selected to ISOLATE then HV-331 will OPEN, the other three valves remaining CLOSED.
This is the situation, for example, during cylinder changing operations.
Attachment A A-45 T
y r
/
/
?n N '"W e h
~
. c jN\\
SCHEMATIC LOGIC DIAGRAM j
s EOR FEED B_ LENDING s'v N
e.
m AND_ LIQUID SAMPLING AUTOCLAVES
'N
~
x s.
s
\\
,'s TSHH - 122 HI HI
' t
's, { ;g ;i 1, AUTOCLAVE AIRTEMPERATURE x
- p, j TSHH - 127 HI HI DE-ENERGlZE
'N, ~~ j/
AUTOCLAVE AIR TEMPERATURE HEATERS
'V OR PSHH - 115 MI HI CONTROL ROOM HEATER AUTOCLAVE AIR PRESSURE TRIP ALARM PSHH - 118 HI HI AUTOCLAVE A R PRESSURE CONTACT L_O_G_i_C JIAGRAM EOR FEED BLENDING m
AND_ LIQUID SAMPLING AUTOCLAVES TSHH - 122 TSHH - 121 P_SHH - 115
_P_SHH - 118 HEATER O
O O
O O
O O
O POWER CIRCUIT (ALL CONTACTORS NORMALLY CLOSED)
(ALL CONTACTORS OPEN ON FAILURE OF CONTROL POWER)
(CONTACTORS OPEN ON RECEIPT OF TRIP SIGNAL) cr.Aisonna: rumenMENTCENTER PftCD*t PROTECTION SYSTEtB FIGURE 6.4-40 E aseta,tes:
FIG 1. RELATIONSHIP BETWEEN UF PRESSURE 8 TEMPERATURE SET PolNT DURING CONTAINER WARH-UP, g
STAND-BY 8 ON-LINE PHASES.
n
- T ~'
UPPER PRESSURE SET PolNT (NOH 2.5 BAR)
=T LOWER PRESSURE SET point
---=p TRIPLE POINT (NOH I.8 BAR) u s
s
~- ----
b* -----
AIR TEMPERATURE s'~~~~~~~~
-SET POINT /
s' U_Fg PRESSUR_E_
f s'
Tm
/
/
/
I I
i WAArt STAND PRES 5tRE ON W
SY SET POINI LINE CtiANGED TIHE s
Q D
'i$j(" p'
'"I O C'? ' P!
q fj p j f
lB un (Nt L di n ;; : W M L j[
in accordance with the procedure described in Section 6.3.1737~
Design Description.
6.3.1.6.2 The inspection and testing procedure for the 48-inch diameter cylinders follows the requirements of ANSI N14.1.
6.3Property "ANSI code" (as page type) with input value "ANSI N14.1.</br></br>6.3" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process..1.7 Instrumentation All process variables are automatically controlled.
Deviations from specified values are detected and indicated via two-stage alarm signals.
At the first alarm level, the process operator has the opportunity to manipulate the process to restore it to normal.
At the second alarm level, automatic action is taken to provide system protection.
Some sensors are duplicated for safety or equipment protection.
Action is initiated if any one out of two duplicated sensors reach alarm levels.
The feed system instrumentation and control system logic are shown in Table 6.3-2, Control Logic UF6 Feed System.
The consequences of exceeding the parameters shown on the Logic Table are discussed in Sections 9.1 and 9.2.
A complete list of the instrumentation is given in Table 6.3-16, Instrument Tabulation.
The autoclave air temperature is monitored to prevent over pressurization of the feed cylinders via overheating.
Normal temperature during heating ranges from 158 to 230 F.
The first alarm level is 230 F to give operator warning of high temperature.
The second alarm level is 239 F and automatical.1 de-energizes the air heater and blower.
The autoclave air pressure is monitored to prevent over pressurization, to indicate UF6 leaks, and to prevent the door from being opened while the autoclave is under pressure.
Normal pressure during heating is 17.6 psia to 19.8 psia.
The first alarm level is 22.0 psia to give operator warning of over pressure.
The second alarm is ucf ps_ia_which automatically de-energizes the air heater and blower.
If the autoclave air ~ ~~ ;gy, g pressure is above atmospheric pressure, the door lock prevents the door from being opened.
To detect small UF6 leaks ths autoclave air pressure and temperature ratio is monitored.
The feed cylinder pressure is monitored to prevent over pressurization of the cylinder, piping and valves.
Normal pressure is 26.1 psia.
The first alarm level is 39.2 psia to give operator warning of over pressure.
The second alarm level at 43.S psia automatically de-energizes the air heaters and blower.
The air heater electrical element surface temperature is ronitored to prevent burn-out.
The alarm level is 302 F and automatically de-energizes the air heaters.
l 6.3-11 March 1992 1
CONTROL AND LOGIC DESCRil'rION - LOUISIANA ENERGY SERVICES, CLAlllORNE ENRICllMSNT CENTER PRODUCT IILENDING SYSTEM DISPLILY NORMAL CPERATION ALARKS I#
CR A
CN CCIDENT LCC CR FROtt LCC CR GROUP Es-301 Receiver container staton state Fcrar position switch.
LCC Per receiving state.
TRMESFER 1 container statice.
CLosE uv-321, NY-341 OPEN HV-311 Transfer valves EV-311 or EV-321 may be TRANSFER 2 CLOSED by MIT-361 in ClasE Kv-341 EV-311 positions TRANSFER 1 CPEN EV-321
& TRANSFER 2 of the receiver container VENT state switch.
CLOKE EV-311, NV-321 OFEN EV-341 VEwr selection for receiver utstion 5
~'15 is only enable' in
'sz HV-321, NY-341, EV-311 states CAs-ovER and CHILL of the deselbleer state switch.32-331 Vacunna/ Nitrogen
/
/
Two position switch.
LCC Per receiving Valve state CPEN OPEN EV-331 container station.
CLost CLosE EV-331 switch Es-331 only selectable to CPEN when vessel state switch Es-301 selected to IsoL.
WI-361 To control the quantity
/
/
will close Transfer line 1 volve
/
/
/
a-Closes Ms0 of UF, added to a receiver EV-311 or Transtar line 2 valve EV-311 station frcan the donor EV-321 as apprcpriate wten or station.
container her reached its preset MV-321
' weight limit.
PI-351 To indloate container
/
Prevents transfer lines or vont
/
H-Closes Per receiver PSE*
inlet pressure.
line being opened to atmospherio EV-321, station.
pressure.
RV-341, a EV-311 Auto-reset.
TIC-To control botbox
/
/
Control of blending system hotbox LCC
/
/
Per hotbom.
te c rature blending temperature.
systeen.
PRODBLND. MIS 8 of 14 March 16, 1992
CONTROL AND LOGIC DESCRII"I' ION - LOUISIANA ENERGY SERVICES, CIAIBORNE ENRICIISIENT CENTER PRODl!CT lli.ENDING SYSTENI DISP 1AY DORMAL OPERATION ALARIES N
I CR A
ON COISEENT LCC CR FRCIE LCC CR GROCP r
ms-400 Product blending
/
/
selectica Ofs LCC MIAT ellows wma up l '.
desublimer state switch.
NEAT desublimer prior to ClosE Desublimer Inlet, EV-403 gas-ever.
Desublimer outlet, EV407 Pasp velve, EV-418 PUIEP STOPPED, e
PT-414 inhibited COLD Fascel OFF
[
i NOT FREON ON PT-411 & PT-412 inhibited r
CAS-OVER QAs-O%1m allows 5
cLost Desublimer Inlet, NV-403 transfer of CLoss Desublimer outlet, EV-407 desublimer contente
% velve. IV-418 to blending receiver PUIEF STOPPED, statlon.
-i PT-414 inhibited COLD PRECEE OFF EDT FREOtt 008 PT-411 s PT-412 inhibited VENT selectica on otetton 5
?
enabled CaILL CnILL ellows CLosE Domublimer Inlet, NY-403 Memblimer to Le l
Desublimer cetlet, EV-407 cooled down Pump valvo,37-418' following completion PUREP STOPPED, ef trap treaefer.
PT-414 inhibited Isots la CMILF- %
COLD FREOst 048 froom will s:p WOT FRSOtt OFF through its ludits PT-411 & PT-412 inhibited cycle.
. VENT selection on stetton 5 enabled l
S/BY
[
CLOst Desublimer Inlet, MV-403 COstTROLIED Docubilmer outlet, NY-407, and pump velve, NV-419 on PT-411 & PT-414 NOT PREOtf OFF COLD FRS0tt 005 PUIEP R05351300, FT-414 & PT-412 enabled 4
'. PRCDBl.ND. MIS 12 of 14 March 16, 1992
,+e w-y e-y n
g n
+-a,,,
_,,w-
_,__,_a
1 BNFL CALCULATIONS SHEET TITLE:
DATE Hex " Pouring" From A Ruptured Cylinder 3 July 1990 1)
Model P
Pi o
t air in x
~
3 hex / air mixture y
1 out Consider a rectangular aperture, height H, and width W.
To the left ("inside") is a mixture of hex (at constant SVP -P ) and air.
t To the right is "outside", at notional pressure P.
There is an o
interface at height y, above which air flows in, and below which the hex /_ air mixture flows out.
The analysis establishes the height of the interface by equating the incoming and outgoing air mass flows (no reaction is assumed to take place between the hex and the air).
These flows are driven by pressure differentials due to density differences.
2)-
Vertical Pressure Gradients
- Inside, Pt = A - p.g.h (1) y l
(where py is the density of the vessels' contents) and outside, P
B - p3.g.h (2)
=
o (where p, is the air density and A & B are constants) l Sheet 1 of 7 Sheets I
.g w.
~1 s.
-]
z.
i
}
3)
Inflow of Air Following Bernoulli, we write:
E P, - P, =
. p,. v3 where v is the velocity at a particular heignt-'h'-in the aperture.
Thus:
3 B - p,. g. h - A + p r. g.h =
. pa. v t
'h'-being measured from the interface.
l-l When h = 0, y =
0 and therefore B must equal A 2. g. h. ( p,,-p,)
a
= v a 2.g.h.D1 P,
and
.......(3) v = /2. g. D. h 3
Now the volume flow is given by:
X X
Qu = W. fv. dh = W./2. g.R fh. dh ;
O O
2 2
= 7.W./2.g.D
.x 2,,,,,,,,,,,,,,,,,,,,,,,,,-(4) 1 4)
Q.utflow of Mixture-f l
l:
-The' outgoing-velocity is determined from H
3 P, - P, =
. py. v Now when h a.y, v r-0 sheet 2 of 7 Sheets:
o l-l ll
'i
._.. -. _.....,. _. _. - _._...;~_
1 Q ~.
3 A - p,. g. h - B + p,. g. h =
. py. v A - B + g.y. (p, - py)
=0 A - B = g.y. (p, - p,)
g.y.(py - p,) + g. h. ( p, - p y) = f. py. v 2
2.g. (p" - p*)
a
.(y - h) =v a 2. g. D,. (y - h) pv 1
V = g/2. g. D,. (y - h) 2 (5)
As before, we integrate to arrive at the volume flow:
y 1
W. g/2. g. D,. f (y - h) 2. dh Dout
=
c 2
2
= W. g/2. g. D
- 3.y 2 (6) a r;
Sheet 3 of.7 Sheets i.
t
__ _.. -. _ -. ~ _.. _ _ _ _ _.. - - _
f 5)
Height of Interface We equate. mass flows of air, le
- Inflow, M,=On Pa i
' p -p^'
- Outflow, M, = 0,ue. p,.
P, r
where P is the notional ambient pressure, and P the hex SVP.
o t
1
'y 1
- p"
. W }2. g. D 3. y
- 2 Thus p,. 25.W.}2.g.D 3
.x
= p,.
2 1
p 2 e 1
D,3 2
e x=D 3
.y (7 )
3 (D ;
1 P* - Ps where D, a P,
Now H=x+y (height of aperture) y=H-x 2 /
il
= H -. D, 3-D 3
2
.y (D ;
2
-H
/+.
7=
......................(8) 3,
,D 2
3 1+D 3 3
rD, 1
i
(-.
l Sheet 4 of-7: Sheets 6
Uf
,-.y
,yss. M, '. e p e
c
- +
v>e N
... s
- _ s',.
. e 6)
IL9x outflow-Equation (8) isL now substituted bac). Into equation (6), giving.
the' outlet volume flow es:
i 2.
X' O ut
- W }2. g. D. 2
.............~t9) o 2
{
C 3
- !i 3
2 il + D3 L
(D;
),
e 1
K.P, then tne hex mass flow rate.is given by Lat phex
=
h i
,le Oout. K. Pg n
2 5I 110)
Mse, = K,.;. Ps. W. ]2. g. D2..
,D 3 i 5.
D s 2
1+D 3
r i Substituting back the "D's" 3
2 W* HI-M=K.P.3., 2. g. ( P" - P',1
..(11) 3 3
r 32 r 31 3
3 pv
[
P - P 3
p, i 2 -
o s
1+
y
\\ Pvd.
L
- o J
7)
Numerical Solution ps = K. Ps y
.From p =-19.26.mgUF6 / litre. torr (at NTP)
Sheet 5 of 7 Sheets 4
Y s
W
[",
e. '
3 pn =
. P.'
g/m (P in Pa)
- q33, K3 = 0.14 4 5, and K, = 1. 2 09 x 10 ~3 (from "ICAO Str.
4 Atmosphere")
~
Furthermore I....
py = Kn. Pn+ ( P, - P ). K, n
Assume P = 60 kPa
]
1 P = 100 kPa, then o
3 p, = 1209 g/m pn= 867n g/m' 3
py = 867 0 + 4 83.6 = 9153.6 g/m
~
^
Thus 1+
- 1.442
(
P s py; o
" ~ '
4.127 m'd. s ec4 and 2
N. g.
Pv
=
For the case of W = H = 20 mm, we obtain from (11),
M = 0.936 g/sec.
Sheet 6 of 7 Sheets
<<l 1..
P (kPa)
Mb_(g/sec) kg/hr i
10 0.077 0.277 20 0.200 0.720 30 0.350 1.260 40 0.523 1.883 50 0.717 2.581 60 0.936 3.370 70 1.182 4.255 80 1.464 5.270 90 1.801 6.484 100 2.311 8.320
=
(Densities have been assumed constant over the temperature range appropriate to P ).
t l
Sheet 7 of 7 Sheets
(