ML20151Y501
| ML20151Y501 | |
| Person / Time | |
|---|---|
| Site: | Paducah Gaseous Diffusion Plant |
| Issue date: | 09/11/1998 |
| From: | Toelle S UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | Paperiello C NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| GDP-98-0193, GDP-98-193, NUDOCS 9809180260 | |
| Download: ML20151Y501 (45) | |
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USEC l
. A Global Energy Company September 11,1998 GDP 98-0193 Dr. Carl J. Paperiello j.
Director, Office of Nuclear Material Safety and Safeguards Attention: Document Control Desk U.S. Nuclear Regulatory Commission
. Washington. D.C. 20555-0001 Paducah Gaseous Diffusion Plant (PGDP)
Docket No. 70-7001 Certificate Amendment Request - Safety Analysis Report, TSR 2.3.2.1 and TSR 2.3.3.1 -
Normetex Pump High Discharge Pressure System
Dear Dr. Paperiello:
l In accordance with 10 CFR 76.45, the United States Enrichment Corporation (USEC) hereby submits l
a request for amendment to the certificate of compliance for the Paducah, Kentucky Gaseous Diffusion Plant (GDP). This certificate amendment request (CAR) proposes to delete Technical l
Safety Requirement (TSR) Sections 2.3.2.1, "Normetex Pump Discharge Pressure," and 2.3.3.1, "Nonnetex Pump High Discharge Pressure System." It also requests revision of the related sections 1
of tic Safety Analysis Report (SAR).
A commitment to provide this amendment request was made in USEC's August 28,1998 Request for Enforcement Discretion related to potential concerns with exceeding the Normetex pump discharge bellows pressure safety limit of 45 psia (Reference 1). As documented in Reference 1 and PGDP Event Noti 6 cation Worksheet No. 34693 (dated August 26,1998), the No. 2 Normetex Pump in Building C-315 tripped while running on stream and a momentary discharge pressure of 46 psia was observed. This is greater than the current TSR safety limit of 45 psia. Following this event, an I
engineering evaluation of the Normetex discharge configuration and the High Discharge Pressure System (HDPS) in Buildings C-310 and C-315 was perfonned which concluded that there is no need to credit the HDPS in the S AR accident analysis. As such, there is no need to include the HDPS or the related safety limit for the Normetex pump discharge bellows in the TSRs. Accordingly, this CAR proposes to delete the associated TSRs, downgrade the classification of the HDPS, and revise the l
SAR to delete the discussion of the HDPS in the accident analysis. Enclosure 2 to this letter provides l
a detailed description andjustification for the proposed changes. Enclosure 3 is a copy of the revised TSR and SAR pages associated with this request. Enclosure 4 contains the basis for USEC's determinadon that the proposed changes associated with this certificate amendment request are not significant.
9809100260 980911 PDR ADOCK 07007001 I
.i U 0 01 ~
C PDR L
j 6903 Rocidedge Drive, Bethesda, MD 20817-1818 Telephone 301-564-3200 Fax 301-564-3201 http://www.usec.com l
Offices in Livermore, CA Paducah, KY Portsmouth, OH Washington, DC l
L Dr. Carl J. Paperiello September 11,1998
. GDP 98-0193, Page 2 Since PGDP has implemented restrictive operating requirements as conditions of the approved Notice of Enforcement Discretion (Reference 2), prompt review of this cettificate amendment request is
. desired. The amendment should become effective 15 days from issuance.
Any questions related to this submittal should be directed to Mark Smith at (301) 564-3244. There are no new commitments contained within this submittal.
Sincerely, A
S. 4.
I Steven A. Toelle Nuclear Regulatory Assurance and Policy Manager
Enclosures:
- 1. Aflidavit
- 2. United States Enrichment Corporation (USEC), Proposed Certificate Amendment Request, TSR 2.3.2.1 and 2.3.3.1 - Normetex Pump High Discharge Pressure System, Detailed Description of Change
- 3. Proposed Certificate Amendment Request, Paducah Gaseous Diffusion Plant, Letter GDP 98-0193, Removal / Insertion Instructions
- 4. United States Enrichment Corporation (USEC), Proposed Certificate Amendment Request, TSR 2.3.2.1 and 2.3.3.1 - Normetex PumpHigh Discharge Pressure System, Significance Determination cc: Mr. Robert C. Pierson (NRC)
NRC Region III Office NRC Resident Inspector - PGDP NRC Resident Inspector - PORTS Mr. Randall M. DeVault (DOE)
References:
- 1. Letter from James H. Miller (USEC) to Dr. Carl J. Paperiello (NRC), Request for Enforcement Discretion, USEC Letter GDP 98-0188, August 28,1998
- 2. Letter from Carl J. Paperiello (NRC) to Mr. James H. Miller (USEC), Notice of Enforcement Discretion for United States Enrichment Corporation (USEC)
Regarding Paducah Gaseous Diffusion Plant, NOED No. GDP 98-1, l-September 1,1998
4 GDP 98-0193 Page1of1 OATH AND AFFIRMATION I, Steven A. Toelle, swear and afErm that l'am the Nuclear Regulatory Assurance and Policy Manager of the United States Enrichment Corporation (USEC), that I am authorized by USEC to sign and file with the Nuclear Regulatory Commission this Certificate Amendment Request for the Paducah Gaseous Diffusion Plant addressing revisions to the Safety Analysis Report and Technical
{
Safety Requirements (Sections 2.3.2.1 and 2.3.3.1) associated with the Normetex pump High Discharge Pressure System, as described in USEC letter GDP 98-0193, that I am familiar with the contents thereof, and that the statements made and matters set forth therein are true and correct to j
the best of my knowledge, information, and belief.
- 5. A.
I Steven A. Toelle On this 1Ith day of September,1998, the officer signing above personally appeared before me, is known by me to be the person whose name is subscribed to within the instrument, and acknowledged that he executed the same for the purposes therein contained.
I In witness hereofI hereunto set my hand and official seal.
hblW L(blf La rie M. Knisley, Notary Public State of Maryland, Montgomery County My commission expires March 1,2002 L
GDP 98 0193 Page1of10 4
United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System
)
Detailed Description of Change As documented in USEC's August 28,1998 Request for Enforcement Discretion (Letter GDP 98-0188) and PGDP Event Notification Worksheet No. 34693 (dated August 26,1998), PGDP experienced an occurrence where the No. 2 Normetex pump in Building C-315 briefly exceeded the Technical Safety Requirement (TSR) Safety Limit (SL) of 45 psia. This was in spite of the action of an operational trip associated with closure of the discharge block valve and the High Discharge Pressure System (HDPS), which is a TSR safety system supposedly designed to prevent the safety limit from being exceeded. This event apparently occurred because of an inadvertent closure of the pump discharge block valve, thus deadheading the pump, and resulting in a rapid but short pressure spike. After the pump stopped, the pressure decreased below the safety limit.
Following this event, an engineering evaluation of the Normetex discharge configuration and the High Discharge Pressure System (HDPS) in Buildings C-310 and C-315 was performed which concluded that there is no need to credit the HDPS in the Safety Analysis Report (SAR) accident analysis. As such, there is no need to include the HDPS or the related SL for the Normetex pump discharge bellows in the TSRs. This Certificate Amendment Request (CAR) proposes to delete TSR Sections 2.3.2.1 and 2.3.3.1. Additionally, it is proposed to revise the SAR to remove credit for the HDPS from the accident analysis and to no longer refer to the system as a TSR system or as a Q safety system. The HDPS in Building C-315 will be re-classified as a non-safety (NS) system. As discussed further below, the HDPS in Building C-310 will continue to be classified as an AQ-NCS system. The SAR sections proposed for revision are 3.4.2; 3.5.2; 3.15; 4.3.3.1.1; 4.4.3.4; 4.9; Chapter 4, Appendix A, Section 2.6.2.5.1; and 5.2.3.1.
10 CFR 76.87 (d) states that the TSRs must include safety limits and limiting control settings (LCSs),
among other requirements. 10 CFR 76.4 defines safety limits as: "those bounds within which the process variables must be maintained for adequate control of the operation and that must not be exceeded in order to protect the integrity of the physical system that is designed to guard against the uncontrolled release ofradioactivity." Limiting control settings are dermed as: " settings for automatic alarms or protective devices related to those variables having significant safety functions." Therefore, in order for a system to warrant inclusion in the TSRs, it must protect the integrity of the physical system to prevent an uncontrolled release of radioactivity and must have a significant safety function.
The HDPS was originally designed to fulfill one specific function. This function was to trip the Normetex pump in the event the discharge pressure exceeded 42 psia in order to protect the physical integrity of the discharge bellows. For the HDPS's original purpose, the accident scenario of concern was the accidental closure of the discharge block valve such that the pump becomes deadheaded.
o GDP 98-0193 Page 2 of10 United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System Detailed Description of Change Subsequently, the HDPS in Building C-310 was credited with a nuclear criticality safety (NCS) function of preventing condensation of HF in the product condensers by preventing the pressure in the condensers from exceeding 50 psia. HF condensation could lead to a loss of moderation control and possible inadvertent criticality in condensers or other areas of the withdrawal system in Building C-310.
l Should the Normetex pump discharge block valve fail closed on an operating Normetex pump, the i
discharge pressure willinunediately spike. When the discharge valve fully closes, an interlock on the
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valve automatically trips the pump and closes the suction control valve. However, the pump does not stop immediately and the suction valve requires a certain amount of time to close, resulting in a continuing pressure rise until the pump stops rotating since the pump outlet is dead-headed.
Although the pump coastdown is brief, the small volume of piping between the pump spirals and the discharge block valve results in a rapid pressure increase. The pressure spike from this event, although short, can exceed the present TSR safety limit for the discharge bellows of 45 psia. The safety limit violation occurred aller an operational trip of the Normetex pump. Even though the pump tripped before the pressure reached the HDPS LCS of 42 psia, the pump coastdown against the closed valve caused the pressure to exceed the safety limit, thus indicating the HDPS would not likely perform its intended function of preventing the discharge bellows pressure from exceeding the safety limit. The maximum amount of UF available to be released as result of valve closure and 6
bellows rupture is less than 5 lbs. (i.e., the material between the pump spirals and the discharge block valve and any material moved through the pump as it coasts down). A release of this size is unlikely to affect anyone not in the immediate vicinity of the release (i.e., on the north end of the C-310 cell floor, or upstairs near the pumps in Building C-315) and workers would evacuate the release area in accordance with the plant "see and flee" policy.
Even if both the operational pump trip associated with the discharge block closure limit switch and the HDPS pressure-related trip failed, the UF release detection system over the Normetex pump (a 6
Q safety system included in the TSRs) would detect the release should the bellows rupture, trip the pump, and close the block valves to terminate the release. The analysis in SAR Section 4.3.3.1.1 concludes that a maxunum release of 250 lbs of UF could be expected in this case. Therefore, based 6
on the definitions of SL and LCS contained in 10 CFR 76.4, the HDPS does not need to be credited for preventing an uncontrolled release of radioactivity because a failure of the system would be safeguarded by the operation of the Normetex pump UF release detection system. The release would 6
be controlled by the UF release detection system which is already in place to mitigate other failure 6
modes of the bellows, piping, and of the pump itself. Failure of the bellows due to a pressure spike
9 GDP 98-0193 Page 3 of 10 United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System Detailed Description of Change is one of two failure modes for the discharge bellows and the UF. release detection safety system would act to control the release for either of these failures.
Although,in accordance with the above comparisons of the HDPS to the criteria for SLs and LCSs, the HDPSs in Buildings C-310 and C-315 are not required to be included in the TSRs, the HDPS in Building C-310 is still credited for nuclear criticality safety and is classified as AQ-NCS. The primary function of the HDPS in Building C-310 is to prevent the condensation of HF in the condensers to prevent criticality concerns in the product cylinders and accumulators. Engineering analyses performed following the recent event have re-confirmed the ability of the C-310 HDPS to prevent the condenser pressure from exceeding 50 psia based on a trip at 42 psia. Double contingency is maintained for the criticality safety upset scenarios involving, or mitigated by, the C-310 HDPS.
Therefore, in accordance with TSR Section 3.11.5, the HDPS in Building C-310 is not required to be included in the TSRs since only controls for singly contingent operations require TSRs.
The specific changes included in this CAR are as follows:
TSR 2.3.2.1. Normetex Pump Discharee Pressure - This TSR and the associated safety limit and basis statement are proposed for complete deletion. The TSR proposed for deletion currently reads as follows:
"2.3.2.1 NORMETEX PUMP DISCIIARGE PRESSURE i
SL 2.3.2.1: The Normetex withdrawal pump discharge bellows pressure shall not exceed 45 psia.
i APPLICABILITY: Modes: All j
BASIS:
1 The limiting concern for determining the SL is the expansion joint integrity. An SL of 45 psia, the expansion joint rating, ensures the integrity of the expansion joint will be maintained [SAR Section 4.3.3.1.1].
In addition to UF. release concerns, meeting this pressure requirement helps meet criticality concerns by 3
ensuring hydrogen fluoride (HF) does not condense in the UF, condenser, accumulator, and/or cylinder. This is important to safety because the cylinder is an unfavorable geometry and moderation control is used to maintain nuclear safety. An 11/U ratio ofless than 0.088 will be maintained if the condenser pressure is maintained below 50 psia because a pressure of this magnitude or below ensures IIF does not condense in the UF, condensers.
[NCSA 3974-05]"
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l GDP 98-0193 Page 4 of 10 i
United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump Iligh Discharge Pressure System Detailed Description of Change l
TSR 2.3.2.1. Normeter Pump Iligh Discharee Pressure System - This TSR and the associated basis statement are proposed for complete deletion. The TSR proposed for deletion currently reads j
as follows.
1 "2.3.3.1 NORMETEX PUMP llIGli DISCilARGE PRESSURE SYSTEM LCS 2.3.3.1: The actuation pressure of the Nonnetex pump high discharge pressure system shall not exceed 42 psia.
LCO 2.3.3.1: The Nonnetex pump high discharge pressure system shall be operable.
1 APPLICA0lLITY: Modes: 2 ACTIONS:
Condition Required Action Completion Time A. One detection / initiation channel A.1 Restore Operability 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> i
B.
Action item A not satisfactorily B.I Place the Normetex pump in Ihour accomplished.
mode 3.
C, Both detection / initiation channels C.1 Place the Normetex pump in Ihour inoperable.
mode 3.
D. Pressure transmitter process line D.1 Verify / place the valve in the Immediately block valve or test point block proper position.
valve found not scaled or in wrong ANI2 position D 2 Rescal the valve 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> l
l SURVEILLANCE REQUIREMENTS:
Surveillance Frequency 1
SR 2.3.3.1-1 Functional test of the automatic trip from each Annually detection / initiation channel. System must actuate at or l
below 42 psia.
SR 2.3.3.I 2 Calibration of each detection / initiation channel.
Annually SR 2.3.3.1-3 Visually inspect the pressure transmitter block valves to Annually ensure they are in the proper position.
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GDP 98-0193 Page 5 of 10 United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System Detailed Description of Change BASIS (continued):
If the pump discharge valve should fail closed on an on-stream Normetex pump, the discharge pressure would rise rapidly and could conceivably rupture the discharge expansion joint bellows releasing UF. if the pump remained in operation. To prevent this type of accident, dual high-pressure shutdown instrumentation is installed on the pump discharge pipe [SAR Section 4.3.3.1.1J.
In addition to UF release concems, meeting this pressure requirement helps meet criticality concerns by ensuring hydrogen fluoride (HF) does not condense in the UF. condenser, accumulator, and/or cylinder. This is important to safety because the cylinder is an unfavorable geometry and moderation control is used to maintain nuclear criticality safety. Moderation control is assumed lost if the hydrogen to uranium (II/U) ratio exceeds 0.088. An II/U ratio ofless than 0.088 will be maintained if the condenser pressure is maintained below 50 psia because a pressure of this magnitude or below ensures iIF does not condense in the UF. condensers. [SAR Section 4.4.3]"
SAR 3.4.2. Normetex Pumps - This section will be revised to remove reference to the 45 psia safety limit. The proposed revision is shown in the following by indicating deleted text with strike-out and added text with italics:
Dual pressure transmitters read the discharge pressure and actuate the pump shutdown circuit at approximately 42 psia iv wduuu un, laidivvd vf dm.he r ymaams nam 3 v o evini dia uu3 n souau o ivaa vf i
uvuiauuuwd Jus iv uayuumuu;uud vi viems lodmu. A 37 psia discharge pressure warning alarm and 39 psia pump shutdown are also included to avoid pumping conditions that might overload the pump motors or potentially damage the pump if allowed to persist. These two latter settings are not associated with the 45 yam aufuiy luun vi 42 yam L353 AG-NCS trip at or below 42 psia, although they share some conunon components and the same ultimate action (pump shutdown)."
SAR 3.4.2. Normetex Pumps - This section will be revised to state that the C-310 Normetex pumps include only one TSR system. The proposed revision is shown in the following:
In addition to nonnal instrumentation and controls, the C-310 Normetex pumps include one system required to be included in the TSR (see Figures 3.4 3 and 3.4-4).
SAR 3.4.2. Normetex Pumps - Description of the HDPS as being required as a TSR system is proposed for deletion. The description to be deleted currently reads as follows:
High discharge pressure shutdown circuit is a system required to be included in the TSR and designed to prevent the mpture of a buffered expansion joint under a blocked discharge line condition. The pump discharge is not directly controlled but is maintained by the pump inlet control valve (controlling pump throughput), the UF. condenser vent valve (controlling pump backpressure), and the control valve on the UF.
condenser inlet (during concurrent pump and condenser startup). If a block valve on the discharge should
l GDP 98-0193 Page 6 of 10 United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System Detailed Description of Change accidently be closed while the pump inlet control valve is open. the pressure rating of 45 psia on the expansion joint could be exceeded if high-pressure shutdown systems fail. Dual discharge pressure transmitters initiate the system shutdown at or before 42 psia."
SAR 3.4.2. Normetex Pumps - This section will also be revised to include a description of the UF6 gas high pressure trip that is credited for the prevention of HF condensation in the condensers for nuclear criticality safety. This description is proposed to read as follows:
"* Pump discharge UF. gas high pressure trip at or below 42 psia (this prevents condensation of IIF in the condensers for nuclear criticality safety purposes in C-310 only)."
SAR Figures 3.4-3 and 3.4-4. Normetex Pump Instrnmutation - These figures will be revised to remove schematics of the High Pressure Pump Shutdown circuitry and to remove the unnecessary indication of safety system status for the PGLD System (system classifications are identified in S AR Section 3.15).
SAR 3.5.2.1. Compression Comoonents - Normetex Pumps - This section will be revised to trmove reference to two TSR systems for the Normetex pumps. The proposed revision is shown in the following by indicating deleted text with strike-out cad added text with italics:
"... This alternate piping allows the pump to be used as an evacuation pump for operations such as evacuating the off-stream flortonsphere. Refer to Section 3.4.2 for a description of the Normetex pumps, including the
- we TS L,a mi - UF Leak Detection Shutdown system (a TSR system).aiid !!!gh OhcMige Picasure Shuideum" SAR 3.15.1.3.8. Normetex Pump High Discharge Pressure System - This section describes the current Q function and boundary of the Normetex HDPS. The section is proposed for complete deletion. The section deleted currently reads as follows
"3.15.1.3.8 Normetex Pump High Discharge Pressure System O Function The function of the Normetex pump high discharge pressure system is to automatically shut down the pump when a high discharge pressure is detected to protect the discharge piping components.
See Sections 3.4.2 and 3.5.2.1 for a description of this system.
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GDP 98-0193 Page 7 of 10 United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System Detailed Description of Change Boundary l
The system boundary includes:
1.
Pressure sensors 2.
Aeociated circuitry to trip the pump 3.
liigh pressure piping to the condensers."
SAR 3.15.1.3.12. C-310/C-315 Condenser. Accumulator and Liauid UF, Process Pining and Valves - This section is proposed for revision to describe the Q boundary downstream of the Normetex pumps. ' The following section will be added:
"4.
Piping / valves containing high-pressure gaseous UF, downstream of the Normetex pumps /hi-speed centrifugal compressors" SAR 3.15.2.12 Cascade Nine and Eaulpment - This section is proposed for revision to describe the AQ boundary of piping up to and including the Normetex pumps. The proposed revision is shown in the following by indicating deleted text with strike-out and added text with italics:
~4. From entry point of building to and including the Normetex pumps /hi-speed centrifugal compressors ceAbs in buildings C-310 and C-315" h
SAR 4.3.3.1.1. Normetex Pump Failure - This section of the accident analysis is proposed for revision to include a discussion of bellows failure from both fatigue and over-pressure. The proposed revision is shown in the following by indicating deleted text with strike-out and added text with italics:
If a fatrgue failure were,to occur on the discharge bellows or outlet piping. UF, would be released into the C-310 building cell floor ama. The discharge bellows couldfailfromfatigue or overpressurization, If the pump ducharge wdw wem tofaitclosed on an on-stnam pump, the discharge pressure would rise rapidly and could conceivably rupture the pump discharge bellows. Assuming a failure of the discharge bellows or piping. and a withdrawal rate of 70,000 lb/ day,50 lb of UF/ min would be released on the C-310 cell floor. "
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GDP 98-0193 i
Page 8 of10 l
United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System Detailed Description of Change l
SAR 4.3.3.1.1. Normeter Pump Failure - This section of the accident analysis is proposed for revision by deleting the discussion of the 42 psia HDPS safety trip that was previously credited with protecting the bellows from over-pressure failure. The section proposed for deletion currently reads as follows:
A second Normetex pump accident scenario was examined. If the pump discharge valve were to fail closed on an on-stream pump, the discharge pressure would nse quite rapidly and could conceivably rupture the pump discharge bellows. To prevent this type of accident, dual high pressure shut-down instrumentation is installed as a safety system on the pump discharge. High pressure will sound an alarm at 37 psia and cause a pump operational trip at 39 psia. The high discharge pressure safety system will trip the pump at 42 psia to prevent exceeding the 45 psia pressure rating (MAWP) of the dischirge bellows. This scenario is of negligible safety concern. A failure of the safety system would result in a source term bounded by the fatigue failure scenano oescribed in the previous paragraph."
SAR 4.4.3.4. Criticality Accident Analysis - Product Cylinders - The second and third full paragraphs of this section will be revised to describe NCS double contingency considerations for the UF product condensers. The proposed revision is shown in the following by indicating deleted text 6
with strike-out and added text with italics:
Double contingency cannot be demonstratedfor large UF, cylinders since moderation is the only control to ensure subcriticaliy. The amount of enriched uranium necessary for a critical configuration depends on geometry, composition, and the introduction of moderator (HI%r water). The exact geometry.. complex nature of the chemical reactions and many other variables. (Situations 2 and 3 above.)
Douhic _..igcr.cy c= bc arac..;.aca for :, U", sma.
m mua. nuu m c,e vid, muununu uim su!~undiy. The most likely moderating material.. chain reaction. The UF, condensers are maintained under strict temperature and pressure controls to ensure the amount of HF is low enough to meet the required 1I/U ratio, and consequently, the UF purity specification. Double contingency is demonstratedfor the control of the 11Fconcentration."
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GDP 98-0193 Page 9 of10
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United States Enrictment Corporation (USEC)
]
Proposed Certificate Amendment Request l
Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System Detailed Description of Change SAR Table 4.9 PGDP Accident Analysis Scenario Summary Table - This table is proposed for revision to combine ccenarios 27 and 28 since over-pressure rupture of the discharge bellows is not considered as a unique failure mode. The proposed revision is shown in the following by indicating deleted text with strike-out and added text with italics:
- 27. Text deleted Ou.ipivaam u uf 4-39+t Relca ia;ide UF, dixhm su hw11vn a vu h.uJiug fowhiy Nuuua 4nididionalemuy
- 28. f ntrgue Failure on discharge 4.3.3.1.1 Release inside UF, of Normetex pump handling facility SAR 4.0 Appendix A. 2.6.2.5.1. Product withdrawal and cylinder filling station - This section is proposed for revision to delete references to the HDPS being a safety system. The proposed revision is shown in the following by indicating deleted text with strike-out:
Detailed analysi of the Normctex pump used for product withdrawal was performed in the Normetex Pump 2
NCSA ' with the results requiring strict controls on pump configuration. Credit was taken in the analysis for the high discharge presswe scfety system to preclude excessive pressures in the system. The high discharge pressure safety system also controls moderation in the withdrawal process (see Fig. 2.6-8).
System integrity for the entire process is of utmost importance to prevent a release of UF, for direct exposure concerns and the potential for criticality. Existing safety systerr.s are used to protect system integrity in this area of operation. "
SAR 5.2.3.1. Nuclear Criticality Safety - Application of Parameters - This section is proposed for revision to delete reference to the HDPS being a safety system and to delete reference to the 45 psia safety limit. The proposed revision is shown in the following by indicating deleted text with strike-out and added text with italics:
The pressure in the product withdrawal system at PGDP is determined by the discharge pressure of the UF product withdrawal (Normetex) pumps. The C-310 Normetex pumps are equipped with 6
a high discharge pressure safety system to picscia e yvssib;c evci-picssarizeueii of dic cmpeiisioiis.in e
iii d>c J,~;uu s p,puig that will actuate the pump shutdown circuit at or below a pressure of 42 psia.
c TLv aofsij ikiia for diis 53 Ani is 45 p m ecJ dic oeaus ceumv: scaieg is 42 psie. Since thc picsau,u er dis pivduci ed.dional sja.u coco,vi cxcccd dic sefsi, liiiiii of 45 psia. pump will trip at or below
GDP 98-0193 Page 10 of 10 l
United States Enrichment Corporation (USEC) l Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System Detailed Description of Change
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apressure of42 psia, the HF cannot condense because it would have to be greater than 50 psia to do so. This ensures moderation control and an atomic ratio below 0.088 in the product withdrawal system."
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GDP 98-0193 30 Pages Proposed Certificate Amendment Request Paducah Gaseous Diliusion Plant Letter GDP 98-0193 l
Removal / Insertion Instructions Remove Page Insert Page j
Volume 1 Section 3.4 Section 3.4 3.4-1/3.4-2, 3.4-3/3.4-4,3.4-11/3.4-12 3.4-1/3.4-2,3.4-3/3.4-4,3.4-11/3.4-12 j
Section 3.5 Section 3.5 3.5-1/3.5-2 3.5-1/3.5-2 Section 3.15 Section 3.15 3.15-19/3.15-20,3.15-21/3.15-22, 3.15-19/3.15-20,3.15-21/3.15-22, 3.15-53/3.15-54 3.15-53/3.15-54 Volume 2 Section 4.3 Section 4.3 4.3-34a/4.3-34b,4.3-35/4.3-36 4.3-34a/4.3-34b, 4.3-35/4.3-36 Section 4.4 Section 4.4 4.4-15/4.4-16 4.4-15/4.4-16 Section 4.9 Section 4.9 4.9-5/4.9-6 4.9-5/4.9-6 Chapter 4, Appendix A Chapter 4, Appendix A 2-71/2-72 2-71/2-72 Section 5.2 Section 5.2 5.2-9/5.2-10 5.2-9/5.2-10 Volume 4 Section 2.3 Section 2.3 l
2.3-4, 2.3-5, 2.3-6 2.3-4, 2.3-5, 2.3-6 1
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SAR-PGDP April 15,1998 Rev. 24 i
3.4 UF. PRODUCT WITHDRAWAL FACILITY The product withdrawal systems for PGDP are housed in C-310 and C-310-A which is attached to and located immediately north of.C-310 ~ The facilities in these buildings provide two complete
. withdrawal systems that permit simultaneous withdrawal of two product streams with different SU concentrations. One system is identified as the top product withdrawal system, while the other system is' designated the side product withdrawal system. Either system can be used to withdraw material of any
, assay up to the plant limit of 2.75 wt % *U. When the C-315 Tails Withdrawal Facility is unavailable,
- t. ails withdrawal may be performed at C-310.
Normetex pumps in C-310 compress the UF., the liquefaction and accumulation is performed in
_.C 310-A, and the cylinder filling operation is conducted in C-310. Each facility has local operating controls and the ACR in C-310 provides additional instrumentation. Fine control of the assay level of the product being withdrawn is accomplished by monitoring of the withdrawal stream with mass spectrometers and/or by analyzing gas stream samples periodically collected during cylinder filling operations.
3.4.1 Description UF from the diffusion e is compressed to a pressure of approximately 30 psia and then cooled 6
to approximately 160*F to condense it. The liquefied UF. flows by gravity into 2%- or 10-ton (or 14-ton for tails only material) cylinders. Each cyliixier being filled is mounted on a scale that monitors the cylinder weight. When the predetermmed cylinder weight limit is aimost reached, an audible alarm on the scale is sounded to alert the operator, and the valve in the UF drain line to the cylinder automatically 6
closes. The filled cylinder is disconnected and moved outside the building for cooling and solidification of the UF product. Noncondensible contaminant gases remaining in the cylinder are removed by
)
connecting the cylinder to the " burp" station at C-310 and evacuating it for several hours. Gases i
evacuated from the cylinder are either (1) routed back to the cascade or (2) passed through sodium l
fluoride traps to remove any UF before discharging the remmining gases to the atmosphere through the C-310 stack.
The components associated with the product withdrawal systems, except product cylinders, are fabricated of corrosion-resistant materials, such as nickel alloys, nickel-plated steel, copper, or aluminum.
Most joints in the withdrawal systems are welded.
3.4.2 Nonnetex Pumps e
I Two Nonnetex pumps are installed on the C-310 cell floor at the north end of cell 9 and cell 10.
L Both pumps are 350 cfm units, which were developed and manufactured in France. The pump at cell 10 was installed as a test unit in 1981 and was tested on air, light gases, and UF. prior to installing the unit at cell 9.
The Normetex pump uses a fixed and a moving spiral vane. The moving vane has an eccentric motion causing " pockets" between the vanes to open and close to compress the gas and move it from the inlet to the discharge of the pump (see Figure 3.4-1). This design permits compression of UF. without the use of dynamic seals between the process and atmosphere. The moving vane is powered by two 3.4-1
+
_ _ _. _ _ _.-._ _.- _ _ - - _. _. ~ _. - - _.. _ _.
SAR-PGDP PROPOSED RAC 98C108 (RO) electric motors. The pump uses three crankshafts. Two are connected to the motors and one is an idler. All are supported by precision bearings.
A spacer column connects the fixed vane to the pump body, and the moving vane is attached to the base of the spacer column by two concentric metal bellows that separate the UF from atmosphere and serve as an 6
1 inlet to the pump. The space between the two bellows is buffered and monitored by instrumentation designed j
to detect a leak from either bellows.
je ne UF enters the pump through fine mesh inlet gas filters designed to prevent any foreign material entry 6
that might increase the wear of the vanes. An inlet control valve regulates the amount of flow through the pump by controlling the suction pressure at approximately 1 psia to 6 psia during normal operation. The pump discharge is then routed to one of the three UF condensers at a pressure of approximately 30 psia. The discharge pressure could be considerably higher than the normal operating pressure under a blocked discharge line condition. A buffered expansionjoint rated at 45 psia internal pressure and 55 psia in the buffer area is installed between the pump and the block valve on the outlet line. Dual pressare transmitters read the discharge pressure and actuate the pump shutdown circuit at approximately 42 psia. A 37 psia discharge l
pressure warmng alarm and 39 psia pump shutdown are also included to avoid pumping conditions that might overload the pump motors or potentially damage the pump if allowed to persist. These two latter settings are not associated with the AQ-NCS trip at or below 42 psia, although they sham some common components and l
the same nitimate action (pump shutdown).
' He pump is lubricated and cooled by oil, which is pumped through sealed passages in the spacer column and the vanes. The oil is returned to the 80-gallon, self-contained oil reservoir by gravity flow through and around the shaft bearing surfaces. An oil heater and oil cooler are used as necessary to maintain the desired oil temperature between 149'F to 185'F. The upper temperature limit prevents expansion of the vanes, while the lower temperature prevents formation of solid or liquid UF.. Either of these problems could cause rubbing i
3#
and subsequent damage to the pump.
A simphfied scherr.atic for the product and tails withdrawal facility showing the location of the Normetex pumps is shown in Figure 3.4-2.
In addition to normal instrumentation and controls, the C-310 Normetex pumps include one system l
required to be included in the TSR (see Figures 3.4-3 and 3.4-4).
UF leak detection system consists of Pyr-A-Larm heads, which are mounted in close proximity to the 6
pump housing and discharge lines. The process control system monitors these heads. This system will alarm when any head fires (sounds a " trouble" alarm) and will shut the pump down and close the outlet block valve if any two adjacent heads are actuated. The pump cannot be restarted until the UF detection system is reset. Additionally, the process control systems fire the detectors every 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to help maintain detector sensitivity. The detector heads can also be fired manually.
2 4"
k 3.4-2 I
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SAR-PGDP PROPOSED RAC 98C108 (RO) l l
The following additional instrumentation is included here for better understanding of the system design
' by the reader. These instruments are not identified as TSR systems:
Watt-meters and thermal overloads on both drive motors with an alarm and shutdown on high power or current. Attached oil pump with a thermal overload and alarm.
Oil system and inlet UF. gas differential temperature indication. If the inlet gas temperature significantly exceeds the oil system temperature, the oil system may not be able to remove the heat of compression, which could cause thermal expansion of the pump vanes leading to pump da.nage.
o Temperature indication on the UF suction and discharge lines, i
6 Flow control with the inlet control valve which fails closed and closes upon pump shutdown.
Outlet block valve, which closes upon pump shutdown.
q Pump shutdown upon outlet block valve closure. An override feature must be manually engaged to allow the pump to be started with the valve closed prior to being placed on-stream, Pump inlet UF. gas high suction pressure trip at approximately 7-psia, which prevents pump overload.
Buffered expansion joints on the inlet and outlet lines.
i Alarms and pump trips associated with oil system problems (e.g., low oil flow, low oil pressure, low oil level,'and high oil temperature).
Pump discharge UF gas high pressure trip at or below 42 psia (this prevents condensation of HF in the condensers for nuclear criticality safety purposes in C-310 only).
3.4.3 Uranium Hexafluoride Condensers The product withdrawal system uses three UF. condensers. Each condenser is approximately 12%-ft long and 11 in.~ in diameter with a pressure rating of 400 psig on the shell side and 75 psig on the tube side. The shell is manufactured with ASTM A-106 steel and the "U"-type tubes in the tube bundle are manufactured from monel to resist corrosion.
l l
3.4-3 i
l I
hiay 31,1996 SAR-PGDP Rev. 3 Thickness measurements are taken on the withdrawal area UF. condensers at least every five years in order to establish corrosion rates, determine estimated remaming life and verify the vessel wall has not been reduced below minimum required metal thicknesses per the current version of the National Boiler Inspection Code.
UF, enters the tube side of the condenser at approximamly 30 psia, where it is cooled and condensed l
to a liquid by R-114 coolant passing through the shell side. The R-114 is cooled with RCW in a coolant condenser similar to the process building coolant condensers.
Not all the gaseous material supplied to the condenser is liquefied. A portion of the UF. flow and that part of the noncondensible gases not entrapped in the liquid UF are returned to the cascade via de condenser vent. These gases are normally returned near the stage of the cascade from which they are withdrawn. However, they may be returned to other portions of the cascade (at a suitable assay match point) or vented to surge drums in one of the other buildings. A vent control valve regulates the condensing pressure and the flow of gases back to the cascade. The condenser pressure is controlled and measured in the C-310 control room. The No. I and No. 2 condensers are part of the product condensing system, and the No. 3 condenser is part of the side withdrawal system, although it may be used for product, side or tails withdrawal.
3.4.4 Uranium Hexafluoride Liquid Accumulators Two UF liquid accumulators serve the withdrawal system. The product accumulator is a 21,000-lb capacity nickel-lined tank used in the top product system. The side accumulator is monel-lined steel with a 4,300-lb capacity. The accumulators located on the second floor below the condensers provide surge volume by " floating
- on the drain line. A vent line with a control valve is provided to permit the return l
of noncondensibles to the cascade and to control pressure.
l Thickness measurements are taken on the withdrawal area UF. accumulators at least every five years in order to establish corrosion rates, determine estimated remaining life and verify the vessel wall has not been reduced below mmimum required metal thicknesses per the current version of the National Boiler Inspection Code.
3.4.5 Cylinder Filling Stations There are two cylinder filling stations or withdrawal positions in normal use in C-310. Each has a cylinder cradle arrangement mounted on a cart, which is moved on a floor track system. A cylinder to be filled is placed in the cradle and the cart is moved into position on a scale at the filling station. A removable pipe or " pigtail" connects the filling station to the cylinder valve. The pigtails used for product withdrawal are similar to those used in the feed facilities. However, withdrawal pigtails are exposed to ambient conditions and are thus susceptible to freeze-out (UF solidifying in the pigtail due to a temperature decrease). For this reason, withdrawal pigtails are wrapped with electrical heat tracing covered with insulating tape to reduce the likelihood of freeze-out. Each cylinder filling station has an exhaust hood connected to a common exhaust duct, HEPA filter, and fan, which is then exhausted to atmosphere. This prevents the accumulation of any residual gases that might arise from withdrawal operations.
3.4-4 o
SAR-PGDP
- RAC 98C108 (RO)
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SAR-PGDP RAC 98C108 (RO)
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Figure 3.4-4. East Normetex pump instrumentation.
3.4-12
i SAR PGDP April 15,1998 Rev. 24 3.5 UF. TAILS WITHDRAWAL FACILITY Withdrawal of UF. tails from the enrichment cascade is accomplished with a compression and liquefaction system quite similar to that used for product withdrawal. The tails withdrawal facility is i
housed in the center portion of C-315. A temporary storage yard for tails cylinders, located east of the tails withdrawal facility, is served by a semi-gantry crane.
3.5.1 Description The two primary purposes of the C-315 building is to provide a cascade surge volume consisting of two 20,000 ft) Hortonspheres (normally, one on-stream and one off-stream) and to compress and condense the tails UF. to permit withdrawal through the withdrawal system (see Figure 3.5-1). The surge volume of the Hortonspheres helps control cascade inventory fluctuations.
These two functions are accomplished by routing the "B"-stream from the bottom of the cascade in the C-331 building (via one or both of two low-speed compressors) to the on-stream Hortonsphere as well l
as using the suction of the Normetex pumps or high-speed compressors. At lower withdrawal rates, a low-speed compressor may not be required. One or more of the three Normetex pumps operate in parallel and discharge to the UF. condensing system. Two high speed compressors in C-315 that are j
maintained in standby can be used in lieu of the Normetex pumps. The flow through the Normetex pumps is normally controlled by the pressure in the on-stream Hortonsphere. The process gas is returned from the on-stream Hortonsphere via a control valve to the bottom of the cascade in C-331 building as the "A"-stream. Since the on-stream Hononsphere floats on the discharge of the low-speed compressors, it provides a surge volume for changes in tails withdrawal as well as flows to and from the cascade.
Expansion joints, valve stems, and compressor shaft seals are equipped with special sealing and buffering systems to prevent leakage.
The UF. from either the Normetex pumps or high-speed compressors is piped at approximately 30 psia to a condenser, where the gas is condensed by cooling to a temperature of about 160*F. The liquid UF. flows by gravity into a 10- or 14-ton tails storage cylinder at one of the four cylinder filling positions. During filling, the cylinders rest on cradles on rail-mounted carts positioned on scales at each station. The scales provide a weight readout and an adjustable audible alarm to alert the operator when that limit has almost been reached. A valve in the UF. drain line then automatically closes to prevent overfilling of the cylinder. Before moving a cylinder from the filling station, an accountability weight is established so that, in the event of an overfill, evacuation of the excess UF can be performed with the 6
cylinder in the drain position. After a cylinder has been filled with tails material, it is carefully transported outside by the use of the air-operated scale cart. It is then lifted by a double-block 20-ton crane and carefully transported to the temporary storage area for tails cylinders where it remains until its contents have cooled and solidified (5-day cooldown period). Only then is the cylinder moved to a long-term storage yard.
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3.5-1
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SAR PGDP PROPOSED RAC 98C108 (RO) 3.5.2 Compression Components 3.5.2.1 Normetex Pumps i
Normetex pumps are used to compress the UF. withdrawal stream from the on-stream Hortonsphere for liquefaction. Three Normetex pumps are installed on the second floor of C-315. The three pumps are 350 cfm units developed and manufactured in France. The Normetex pumps are operated with one or more runmng in parallel, taking a suction from the header supplied by the low-speed compressors and discharging to one or more UF condensers, which are also operated in parallel. Additionally, the No. 3 Normetex has 6
an alternate suction and discharge valves that enable compression from a separate source. This could allow tails withdrawal at a second assay value. However, a second assay is not normally withdrawn in C-315. Tids alternate piping allows the pump to be used as an evacuation pump for operations such as evacuating the off-stream Hortonsphere. Refer to Section 3.4.2 for a description of the Normetex pumps, including the UF.
Leak Detection Shutdown system (a TSR system).
l A location and piping plan for the Normetex pumps is shown in Figure 3.5-1.
i 2.5-2
l:
l l..
' SAR-PGDP PROPOSED
' RAC 98C108 (RO) 1.
Gamma detector channel -
2.
Cluster logic module 3.
Cluster housing 4.
Associated circuitry 5.
Local electric horn l
6.
Backup battery for the cluster and horn l.
7.
Connecting cable to connect to the building system 3.15.1.3.8 Text Deleted l
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3.15.1.3.9 Product and Tails Withdrawal Area 2040u Overhead Bridge Cranes O Function l-i L
The cranes (one each in C-310 and C-315) function to safely move liquid-filled cylinders from the scale l
cart to the storage area.
~
See Section 3.4.8.2 and 3.5.8.2 for a description of this system.
Boundarv The system boundary includes:.
i 1.
Crane structure and structural supports, the crane rails, the bri<!ge, the mechanical rail stops at the end l.
of the bridge, the trolley rails, the trolley, and the reeving.
l 3.15-19 i
l
~ ~ +
SAR PGDP July 26,1996 L
Rev.4 i-D.C. rectified shoe brakes L
2.
3.
Relays for hoist brake control 4.
Hoist motor contacts 5.
Geared up/down limit switch l-6.'
Two paddle-type limit switches p
7.-
Emergency stop button 8.
Proximity switches 9.
Associated circuitry p
l The crane brake fails safe on loss of power.
l 3.15.1.3.10 UF Cylinder Lifting Fixtures i
O Function 1
Liquid UF cylinder lifting fixtures are built and maintained to prevent the dropping of a cylinder,
[
resulting in a possible release.
l See Sections 3.4.8.2 and 3.5.8.2 for a description of this system.
L Boundarv -.
The system boundary includes:
1.
Wire rope legs 2.
Lifting fixture asser1bly.
3.15.1.3.11 Scale Carts O Function The function is o safely move cylinders containing liquid UF..
See Sections 3.4.2.1 and 3.5.8.1 for a description of this system.
Boundary i
. The system boundcry include 1.
Cradles and substructure system.
3.15-20 i
SAR-PGDP RAC 98C108 (RO) 3.15.1.3.12 C-310/C-315 Condenser, Accumulator and Liquid UF. Process Piping and Valves O Function The UF. condensers and accumulators (C-310 and C-315) and associated piping and valves were designed to safely contain liquid UF and to provide the means to withdraw UF. from the cascade.
6 i
See Sections 3.4.3,3.4.4,3.5.4, and 3.5.5 for a description of this system.
Boundary The Liquid UF. Process Piping and Valves system boundaries include:
1.
Condenser 2.
Accumulator vessels 3.
Piping / valves contairung liquid UF. from the condenser through the withdrawal manifold.
4.
Piping / valves containing high-pressure gaseous UF. downstream of the Normetex pumps /hi-speed centrifugal compressors
)
3.15.1.3.13 UF, Cylinders O Function Cylinders utilized to contain UF. have been designed, built and tested to ANSI N14.1 and a prescribed mmunum volume specified in USEC-651. This ensures safe containment of UF. during transport, sampling, feeding, filling, and storage and to prevent a release ofliquid UF.. The issue of fail safe is not applicable to this system.
The 2S and 1-kg cylinders are not included as Q due to their small size. These cylinders are classified as AQ.
See Sectio 3.7.1 for a description of this system.
Boundary The system boundary includes:
1.
Cylinder 2.
Cylinder valve 3.
Cylinder plug.
The valve protector has been identified as AQ.
3.15-21
SAR PGDP May 31,1996 Rev.3 3.15.1.3.14 UF, Pigtails O Function UF. cylinder pigtails are designed to safely transfer liquid UF. from the enrichment process to a cylinder during withdrawal operations.
'See Sections 3.4.5 and 3.5.6 for a description of this system.
Boundary The system boundary includes:
1.
Pigtail assembly, including the tubing, adapter, and gaskets.
3.15.1.4 UF. Sampling and Transfer Facility Q systems for the C-360 Toll Transfer and Sampling Facility are listed.
3.15.1.4.1 Autoclave Water Inventory Control System O Function The system function is to isolate the sources of condensate upon detecting a high condensate drain line water level in order to prevent over-pressurization of the autoclave or the possibility of a criticality upon a UF. release.
See Section 3.6.7.3 for a description of this system.
Bounderv The system boundary includes:
1.
Condensate level probes:
2.
Steam supply block valves 3.
Thermovent block valve 4.
Air supply 5.
Solenoid valves and piping to the block valves 3.15-22
SAR PGDP PROPOSED RnC 98C108 (RO) 3.15.2.11 Cascade Piping and Equipment AO Function Provides UF containment (pressure boundary) during the enrichment process.
6 See Section 3.3.1.2 and 3.3.4.5 for a description of this system.
Boundary Cascade piping and equipment includes UF. process gas piping 2 in. and larger, expansion joints, valves, and process equipment containing UF..
System Boundaries 1.
From the second autoclave isolation valve to the exit point from buildings C-333A, C-337A 2.
From C-360 second autoclave isolation valve up to and including evacuation drums (which can be evacuated to C-337) i 3.
From entry point into building to exit points in buildings C-331, C-333, C-335, C-337
~ 4.
From entry point of building to and including the Normetex pumps /hi-speed centrifugal compressors in l
buildings C-310 and C-315 l
l 5.
UF. tie lines: all buildings from entry / exit point to next building entry / exit point Only the characteristics of the listed equipment which provide the UF containment function are controlled as AQ SSCs. Internal parts (e.g., compressor blades, valve gates, barrier, etc.) that do not form part of the UF pressure boundary are not AQ.
6 3.15.2.13 Non-radiological Chemical Systems AO Function The non-radiological chemical systems provide containment of non-radiological chemicals identified as part of the chemical safety program in Section 5.6.
See Sections 5.6.13.2, 5.6.13.3, 3.8.3, 3.8.4, and 3.4.9.
Boundary Chlorine System 1.
For C-611-B, C-611-S, and C-615, the vacuum regulator and chlorine leak detectors and associated alarm.s.
3.15-53 1
SAR-PGDP April 15,1998 Rev.24 2.
For C431, C433, C435, and C437 all piping components including the flexible connection, pipe, valves up to and including the vacuum regulator and the chlorine leak detectors and associated alarms.
CIF System 3
1.
The distribution piping from the chlorine trifluoride storage tank including the flexible connection, pipe and valves 2.
The instrumentation that controls the tank pressures to less than atmospheric pressure 3.
The chlorine trifluoride leak detectors and associated alarms F System
- 1. - The fluorine storage tanks and distribution piping including the flexible connection, pipe, valves, and relief devices 2.
Fluorine leak detectors and associated alarms.
3.15.2.14 Cell Remote Manual Shutdown System i
l AO Function The cell remote manual shutdown system manually shuts down the cell operation in case of emergencies.
See Sections 3.3.7.2.1, and 3.3.7.2.3 for a description of this system.
Boundary l
The system includes:
1.
Manual shutdown button or switch in the Area Control Room (ACR), at the Local Cell Panel (LCP),
and on the cell floor I
2.
Red Air Circuit Breaker (ACB) indicating lights in the ACR and at the LCP 3.
HAA auxiliary relays at the process substations 4.
ACB trip coil and auxiliary contacts, the 250 voit DC break'ers, battery and charger S.
"00" ACB housing switch l
l 6.
51X-2 "00" auxiliary relay 7.
15 kV ACB air tank and pressure switch in "000" 3.15-54 l
l
4 e
SAR PGDP PROPOSED
?.AC 98C108 (RO) and is monitored to detect any leaks. A pressure change of i 0.75 psi between the bellows would cause automatic pump shutdown and alarm. Consequently, no release of UF is expected from a fatigue failure in 6
a concentric bellows.
If a failure were to occur on the discharge bellows or outlet piping, UF would be released into the C-310 6
building cell floor area. The discharge bellows could fail from fatigue or overpressurization. If the pump discharge valve were to fail closed on an on-stream pump, the discharge pressure would rise rapidly and could conceivably rupture the pump discharge bellows. Assuming a failure of the discharge bellows or piping, and a withdrawal rate of 70,000 lb/ day,50 lb of UF / min would be released on the C-310 cell floor. This release 6
could continue until the pump is automatically shut down by the UF detection safety system. A conservative i
6 source term for this low probability accident would be 250 lb of UF released. A more realistic source term 6
would be 100 lb of UF released over a 2 minute period due to the close proximity of UF detectors to the 6
6 pump. The alarming of any two adjacent detectors will actuate the pump trip circuit and shut down and isolate the pump. This release is further mitigated in that it would occur on the cell floor of C-310. The building would provide holdup of reactants and would slow the release to the environment.
4 s
W t
4 4.3-34a
SAR-PGDP May 31,1996 Rev.3 l
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4.3-34b
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ISAR-PGDP -
PROPOSED RAC 98C108 (RO) i
' f 4.3.3.1.2 Con' denser and Accumulator Failures The UF. accumulators and condensers are built in accordance with the ASME Boiler and Pressure Vessel (B&PV) Code,Section VIII. They are inspected at five-year intervals in'accordance with the current edition of the National Board of Inspection Code (NBIC). Tests have shown there has been no appreciable loss of.
metal from either the C-310 or C-315 accumulators. A fatigue failure of components located between the Normetex pump and the product condensers would result in the release of UF as described in 4.3.3.1.1. A
. failure between the condenser and the drain station block valves would result in a release from the liquid UF.
1 portion of the system.
- 'Ihe rupture of a withdrawal system component containing liquid UF. could result from a fatigue failure of an instrument line on the accumulator or the fatigue failure of the drain line from the accumulator.' The worst case in_either of these low probability accidents would occur if the accumulator was partially filled
. during the change out of UF drain cylinders at the withdrawal station.
)
)
'The instrument line break is characterized by a leak from a severed W in. diameter copper tube. In this instance, the UF is esumated to leak out of the system at a rate of 133 lb/ min. A leak on the dmin line could be larger depending on the location and type of break, but in no case would the total leak be greater than 1,000
. Ib of UF..
The high voltage UF, detection system located in this area will alarm in the C-310 ACR and in C-300, but does not initiate automatic actions. It is assumed that this system would alarm in approximately 15 see and alert the C-310 ACR operator to a possible release. The ACR operator would don full protective equipment, physically verify the release, notify C-300, and return to the ACR to perform valving operations to isolate the leak and reduce the system pressure by evacuation. These actions could require up to 40 minutes to i
accomplish. If the release is small, the lengthy response would not increase the total release above the 1,000 lb estimate. If the release approaches 133 lb/ min, the release will be readily apparent from outside the facility, and the ACR operator would initiate mitigative steps. These operations are estimated to require no more than 5 minutes to complete from the start of the release until the system is evacuated.
The UF.detec ion system is a safety system: however, the valves, controls, etc., used in the isolation and evacuation of the condensers and accumulators are not identified as safety system components due to the varied and diverse means available for system evacuation. If the UF. condenser vent valves and the accumulator vent
. valve fail to open, the system can be evacuated through the pump evacuation valves or the evacuation valves i.
at the withdrawal stations. These actions may take longer than 5 minutes to accomplish if personnel protective p
equipment must be donned to access these areas.
I 4.3-35 t
i
--u u
a w
n
SAR-PGDP May 31,1996 Rev.3 4.3.3.1.3 Valve and Pigtail Failure l
De worst-case accident scenario considered possible at the product withdrawal station is a complete l
rupture of the drain manifold to cylinder pigtail with the accumulators partially full. This could result from an inadvertent scale cart movement while the pigtail is attached. In analyzing this scenario, it is assumed the cylinders receiving the liquid UF. are always filled with the valve in the 12 o' clock position.
l The testing and inspection of pigtails before UF. service reduce the likelihood of this accident. A
- key-operated interlock switch shuts off the air supply to the cart, and administrative controls require the key ring to be placed on the pigtail when it is connected to a cylinder. In addition, a pressure sensor on the drain line prevents cart movement unless the pigtail is at atmospheric pressure, ( 3 psi). However, should the l
pigtail become completely severed and dislocated, UF would escape from the manifold end of the severed l
pigtail at a rate of 20 lb/sec and from the cylinder end at a rate of 80 lb/ min.
l The withdrawal areas at PGDP are equipped with a UF. release detection and isolation system which I
includes two, fast-acting block valves on each drain manifold and a valve closer on each cylinder valve as I
described in SAR section 3.4.7. A= ming a 5 sec response time for the UF. detection unit, a 1 see closure I
time for the manifold block valves, and 10 see for the cylinder valve closer to operate, the total outleakage from this medium probability accident is 140 lb of UF.. Although testing at C-360 tends to support these closure times, the valve specifications accept longer times. This scenario will be reevaluated in the ongoing GDP Safety Analysis Report (SAR) Upgrade Program.
The evaluation presented above is the existing safety basis analysis for a valve or pigtail failure at the l
production withdrawal station. However, the assumed release detection and valve actuation times may not be conservative. De release has been recalculand based on more conservative values for detection time (15 sec),
block valve closure time (15 sec), and cylinder valve closure time (30 sec). Using the same release rates assumed above (20 lb/sec liquid release from the manifold end of the break and 80 lb/ min gaseous from the cylinder end), the total release would be 660 lb of UF.. This higher value reflects an upper bound for this potential release and has been used in the TSR basis statement.
l 4.3.3.1.4 Buffered Valve and Flange Failures l
The enn~q=nces of failure of buffered valves or buffered flanges are difficult to evaluate because of the failure *Cm involved. These systems are designed primarily to protect against releases resulting from metal fatigue type failures in the thin metals used in these applications. Valve bellows will occasionally fail, but the eley rates will vary with the degree of damage. Buffer systems are monitored so that leaks are readily detected and can be isolated.
The potential accidents and releases described above have negligible safety consequences. Any small amounts of hazardous material which might escape into the facility from a heated enclosure containing these expansion joints and valves would be readily detected by both sight and odor before they reached hazardous proportion. That would enable operating personnel to evacuate the immediate area and notify the ACR 1
operator to isolate the leak and activate emergency response personnel. Because of this low risk situation, these buffer systems are not considered to be safety systems.
4.3-36
O SAR-PGDP PROPOSED RAC 98C108 (RO)
Before a critical configuration can exist in any of the pits, a well moderated uranium solution would have to accumulate to a depth of at least 5 in. Thus, the criticality accident of concern for pits in C-360 is from an accumulation of uranium and moderator, most likely in the form of water, in one of the pits. For such a scenario to occur, a large release of UF would have to happen and that uranium would have to reach the pits.
6 Second, sufficient moderator would have to be present in the pit. In order for the water to be in the pit, the sprinkler system would have to release water or the wate would have to already be there in the pit when the uranium arrived.
Uranium could enter the pits through a release of UF. in an autoclave, through a handling incident in or around the scales or elevator, or by a chronic accumulation of uranium from many small releases such as those which can occur during pigtail disconnection. An automated water sensor and alarm system is in place in the elevator pit to detect the presence of a water accumulation prior to achieving a depth of 5 in. If water is detected in the pit, an audible alarm is actuated and immediate action is taken to remove the accumulated water. A quarterly inspection of all the pits and drains is performed to verify that no uranium deposits are accumulating and to verify that the pit drains and elevator pit sump pump are operational.
Two oil interceptors are in C-360 so that all of the floor drain lines to the storm sewer must pass through them. During a UF. release, it could be possible to introduce uranium into these interceptors which could contain moderator in the form of oil and water. For this reason, valves in the effluent lines automatically close when a release is detected in the building. This would prevent a significant amount of uranium from entering i
the oil interceptors. Should these valves fail to close, hundreds of pounds of uranium would have to mix homogeneously with the oil or water in the interceptors before it approached criticality.
4.4.3.4 Product Cylinders i
The product cylinders used at PGDP to store UF. vary in size. Under the right conditions it is possible j
to have a criticality resulting from a rupture of a large cylinder and/or from the addition of moderating material to a cylinder containing enriched uranium. Three situations are postulated that could result a critical configuration:
1.
withdrawal of a moderator in the form of HF along with UF into a cylinder during the filling process 6
which could result in a criticality by exceeding the acceptable H/U ratio; 2.
in the event of a leak or rupture of a large cylinder, the addition of a large amount of water into the cylinder which reacts with the contents and results in a critical configuration; 3.
rupture of a cylinder which releases uranium compounds to atmosphere, and that material precipitates out of the atmosphere by rain or water spray and accumulates in solution in an unfavorable geometry outside the cylinder.
Double contingency cannot be demonstrated for large UF. cylinders since moderation is the only control l
to ensure subcriticality. The amount of enriched uranium necessary for a critical configuration depends on geometry, composition, and the introduction of moderator (water). The exact geometry of a mixture of UO F 2 2 and water resulting from a UF. release from a ruptured cylinder or from introducing moderator into a cylinder containing enriched material is nearly impossible to predict due to the complex nature of the chemical reactions and many other variables. (Situations 2 and 3 above.)
l 4.4-15
.___.-...m__
m.
SAR-PGDP PROPOSED RAC 98C108 (RO)
The most likely moderating material to be encountered in a cylinder is HF that is fed to the withdrawal l
cylinder through the cascade. Using moderation as the primary nuclear criticality safety control for product cylinders is based on the ability of the gaseous diffusion plants to produce high purity UF. (= 99.5% pure).
This purity corresponds to an H/U ratio of approximately 0.088. Assuming the remaining 0.5 % impurity was composed entirely of HF, it would not provide sufficient moderation of the neutrons to sustain a nuclear chain reaction. The UF. condensers are maintained under strict temperature and pressure controls to ensure the amount of HF is low enough to meet the required H/U ratio, and consequently, the UF purity specification.
6 Double contingency is demonstrated for the control of the HF concentration.
l Once filled with UF., necessary controls are implemented to ensure that the integrity of the cylinders is maintained. Specifically, administrative controls are in place to (1) visually inspect for cylinder damage or corrosion, (2) space cylinders containing liquid UF. to minimize the possibility of cylinder damage during handling, and (3) restrict cylinder handling such that cylinders containing liquid UF are not lifted over other cylinders nor stacked and that cylinders are not lifted over liquid cylinders.
4.4.3.5 Accumulators The two UF. accumulators which serve the product withdrawal system are located in C-310A. ' The product accumulators are large and resemble a 10-ton product cylinder.. The side withdrawal accumulator, also in C-310A, is smaller and has a capacity of 4300 lb. The accumulators provide a surge volume for the UF. withdrawal process.
Moderation control, as described aoove for the product cylinders, is the primary barrier to criticality in the accumulators. Uranium enriched to 6 wt % nU or less cannot achieve criticality unless moderation is 2
present. Since UF. readily reacts with moisture to form UO F and HF, it is necessary to keep the cascade 22 free of moisture. Therefore, the entire system design is meant to preclude introduction of moisture into the cascade. The only mechanisms for moisture to enter the system are for the moisture to come through the product withdrawal pumps from the cascade, for the system to leak (wet air inleakage), or for purge gas (N2
. or air) laden with moisture to be misdirected into the UF. product header.
Moisture in the cascade would react with the UF. gas before it reached the Normetex pumps and would have formed HF gas. The HF gas released in the cascade would pass through to the product condensers and be vented, or be passed to the cylinder, where it would later be purged in the burping of the cylinder. The temperature and pressure in the withdrawal system are maintained to keep the HF concentration low enough that the H/U ratio in the system is low. Since the product withdrawal system is kept at pressures well above atmospheric pressure, any breach of the system integrity would cause the UF present to be released to the atmosphere, rather than allowing air to leak into the system.
- 4.4.3.6 C-310 Scale Pits The scale pits in the C-310 product withdrawal system are approximately 8 ft wide by 12 ft long and are located beneath each drain station. Before a critical configuration can exist in the scale pits, a uranium solution would have to accumulate to a depth of at least 5 in. This represents a significant quantity of uranium and moderator.
4.4-16 I
J-
Table 4.9-1. PGDP accident scenario summary table. (Continued) gh
&b At Suhatmospheric Operation At Full Power Operatism O O Worst Case Prob. per o "O C
Number / Initiating Event Section Accident Year Maximum llazard Maximum llazard Source Term level Risk Source Term level Risk
$f&
- 23. UF6 Ilydrocarbon oil 4.3.3.5 Release inside UF.
Extremely 28,000 lbs UF.
Medium Extremely 28,000 lbs UF.
Medium Extremely reaction in UF.
handimg facility imw (A)*
(4)
Imw (4) tow c31inder
- 24. Liquid cylinder 4.3.4.1.5 Release outside low (B) 28,000 lbs UF.
Medium low 28,0tX)1bs UF.
Medium Low drop / impact UF. handling (4)
(4) facilirv
- 25. Fatigue / break of 4.3.3.1.3 Release inside UF.
Medium 140 lbs UF.
Extremely few 140 lbs UF.
Extremely lew pietail handling facihty (C) low (2) low (2)
- 26. UF. cylinder valve 4.3.3.2 Release low (B) 720 lbs UF.
Extremely Extremely 720 lbs UF.
Euremely Extremely failure inside/outside UF.
Iow (2) low low (2) tow handling facihty l
- 27. Text deleted p
c6
- 28. Failure on discharge 4.3.3.1.1 Release inside UF.
Iow (B) 250 lbs UF.
Extremely Extremely 250 lbs UF.
Extremely Extremely l
of Normeten pump handling facility Iew (2) law law (2)
Iow
- 29. C-315 compressor 4.3.4.1.1 Release inside UF.
lew (B) 50 lbs UF.
Extremely Extremely 50 lbs UF, Extremely Extremely failure from thermal handling facility low (2) low low (2) low reaCrion
- 30. C-J15 compressor 4.3.4.1.1 Release inside UF.
Medium 5-10 lbs UF.
Extremely low 5-10 lbs UF.
Extremely low seal failure handling facility (C)
Imw (2) low (2)
- 31. Fatigue failure of 4.3.3.1.2 Release inside UF.
Low (B) 1,000 lbs UF.
Extremely Extremely 1,000 lbs UF.
Extremely Extremely accumulator handimg facility low (2) low low (2) low instrument hne i
o
w 4
Table 4.9-1. PGDP acddent scenario s====ary table. (Conti===d) gut At Subatmospheric Opetation At Full Power Opesasson Wars: Case Prob. per O
Number / Initiating Event Section Accident Year Maximum liarard Risk Maainmsm Harned
- Risk N
Sousco Terna 1 svel Source Term -
Level
- 32. Fatigue failure of 4.3.3.1.2 Release inside UP.
law (8) 1.000 lbs UP.
Emisensely Eassesnely 1.000 lbe UP.
Esteesnely Eatseasty accustulator drain line handlang facility 14w (2) law Low (2) law
- 33. Uranium solution in 4.4.5 Crisicalisy Bassesnely 10" P6h Mediuni Entseasely 10" Pissions Mediusa Entsesnely non-geometrK Imw (A)
(4)
Im, (4g g,,
contiguratum
' Ibis probability inu-ludes currem operations best does not inchede secycle of emissing sails cylinders (see Section 4.3.1.5).
cb a
a G
m m
o f
SAR-PGDP Chapter 4, Appendix A April 15,1998 Rev. 24 pump discharge pressure is maintained by regulating the condenser vent valve to maintain the proper condensing l
temperature and pressure.
l The product withdrawal system uses three US condensers. He UF. condenser consists of a tube bundle enclosed in a cylindrical-shaped container approximately 12.5 feet long and 11 inches in diameter. UE enters the condenser tube bundle where it is cooled and condensed to a liquid by R-114 coolant passing over the bundle. The R 114 is in tum cooled with RCW in a coolant condenser similar to the process building coolant I
condensers. Not all of the gaseous material supplied to the condenser is liquefied. A portion of the UV flow and that part of the noncondensible gases not entrapped in the liquid US are normally retumed to the cascade j'
of gases back to the cascade. The condenser pressure is controlled and measured in the C-310 control room.
via the cell below the product withdrawal cell. A control valve regulates the condensing pressure and the flow The No. I and No. 2 condensers are part of the product condensing system and No. 3 condenser is part of the side withdrawal system.
Two accumulators serve the withdrawal system by storing liquid US, if required. One of the accumulators (Top Withdmwal System) is a tank with a 21,000-lb capacity. The other accumulator (Side Withdrawal System) is a tank with a capacity of 4300 lb. The accumulators are located on the second floor below the condensers and provide surge volume by "ficating" on the drain line. A vent line with a control valve is provided to permit the retum of noncondensibles to the cascade and to control pressure.
There are two cylinder filling stations in normal use in Building C-310. Each station has a cylinder cradle arrangement mounted on a cart which is moved on a floor track system. A cylinder to be filled is placed in the cradle and the cart is moved into position on a scale. The scale is located in a large pit at the filling station. He scale cart is a low profile design with a skirt with sloped sides to inhibit inadvertent admission of UE and its reaction products into the scale pit. The scale pit covers are designed to divert liquids away from the pit. While l
liquid UF is being drained into the cylinder, the weight of the material transferred can be read from the scale 6
to determine when the cylinder fill limit has been reached. Before the cylinder weight limit is reached, an alann on the scale set at slightly below the cylinder fill limit sounds to alert the operator. A valve in the Uf drain line i
is then automatically closed to prevent overfilling of the cylinder. The cylinder fill manifold is then purged, l
evacuated, and disconnected. He cylinder is then moved to the cylinder yard for cooling. Normal convection cooling is sometimes supplemented with water spraying.
l After the liquid UF. product has cooled and has solidified, the cylinder can be connected to a manifold at l
the C-310 burp station. This manifold contains two exhaust lines. One exhaust line is for cylinder pigtail purge l
gases, which are exhausted to the cascade purge system in Building C-310; the other line is to a NaF trapping system which absorbs any UF. that might be pulled from the cylinder. The cylinder pressure is evacuated with an ejector to a pressure of less than 10 psia by exhausting noncondensibles such as R 114 or inert purge gases.
l The evacuated gases are discharged through NaF chemical traps. For more details on trap opemtion, see Sect 2.6.2.7.
He original product and side withdrawal operation used Twelliott pumps and associated equipment his l entire system is not in use anymore and is isolated, cut, and capped from the withdrawal equipment currently I
in use. He Twelliott system cannot be put back into service without NCS approval.
l l
Instrumentation. An on-line assay spectrometer normally provides continuous monitoring of the assay l
level of the product. A very small amount of US is sampled at the same point of product withdrawal as a continuous sampling operation. This sample becomes the official sample on which the assay of the contents of l
the filled cylinder is based.
l Physical changes to the NaF traps and associated instrumentation are discussed in Sect 2.6.2.7. The only other physical changes in this area of operation were to the burp stations described above. This change reduced the dike height to 3.5 inches to maintain a favorable geometry for collection of accidental spills. Some controls l l
are required to address the potential enrichment of assays greater than 2 wt %5 U. For additionalinformation on Product Withdrawal Operations, see Sect 3.4 of the SAR.
l 2-71 l
O PROPOSED SAR PGDP Chapter 4, Appendix A RAC 98C108 (RO)
The criticality safety is based on the information in NCSE of the Normetex Pumps Usedfor UF.
WitMrawal at PGDP, KYlE-144*', and NCSEfor Product %?hdrawal in the C-310 Building at PGDP, 3974-0 5.22 System analysis It was determined from the analysis in Sect. 4 that the only significant hazard due to HAUP during product withdrawal operations is criticality.
The criticality concerns for the product withdrawal process are primarily moderation control and maintaining system integrity.
Detailed analysis of the Normetex pump used for product withdrawal was performed in the Normetex Pump NCSA ' w th the results requiring strict controls on pump configuration. Credit was taken in the 2
analysis for the high discharge pressure system to preclude excessive pressures in the system. The high discharge pressure system also controls moderation in the withdrawal process (see Fig. 2.6-8). During the withdrawal process, the limits on the H/U ratio in the product cylinders will be maintained to less than or equal to 0.088 as indicated in USEC-651". This applies to all types of cylinders in addition to all assay levels.
Further detail on use and handling of cylinders during withdrawal operations is included in Sect. 2.6.2.6.
System integrity for the entire process is of utmost importance to prevent a release of UF for direct exposure concerns and the potential for criticality. Existing systems are used to protect system integrity in this l
i area of operation. Specific analyses of the product withdrawal processes are available in the NCSAs for C-310 22 24 Operations and the Cylinder Burp Station,
Safety features and controls As required, design features for safety, administrative controls, and surveillances were developed to support operation at enrichments up to 5.5 wt % uSU. These safety features are listed below.
Design features for safety. The scale carts are designed to have a low profile with a skirt with sloped sides to inhibit inadvertent admission of UF and its reaction products into the scale pit. The scale pit covers 6
designed to divert liquids away from the pit.
Administrative controls. The Product Withdrawal Facility and equipment contained therein shall not be operated at assays greater than 2.75 wt % "5U.
2.6.2.5.2 Cylinder handling Cylinder handling for all areas of product withdrawal operation is addressed in Sect. 2.6.2.6.
2.6.2.6 UF. Cylinder Handling 2.6.2.6.1 Standard UF, cylinders System description The cylirders normally used for transport and storage of UF. feed, product, ard tails materials are the 48-inch-diameter 10- and 14-ton heavy and 14 ton thinwall cylinders, and the 30-irrh-diameter 2.5-ton cylinders. Current cylinder data and handhng gudehnes are in accordance with USEC451". At present the Nuclear Regulatory Commission (NRC) and the Department of Tuuornhih (DUT) regulate transport of these 2-72
i l
SAR-PGDP July 26,19%
Rev.4 In addition to the NCS surveillances the operating organizations perform surveillances. At a minimum fissile material operations are reviewed for NCS on an annual basis (i.e., every 12 months not to exceed 15 months between surveillances). These surveillances are performed by the operating orgaruzation. NCS personnel are also present dunng these surveillances to provide NCS technical support as r~=M 'These surveillances include the inspection of facility modifications, operating procedures, l
compliance with NCSAs, postings, and waste generation and handling. These surveillances are performed as specified by the NCS procedure.
' PORC provides review of the NCS program in accordance with the Technical Safety Requirements. l Independent oversight is provided by internal audits of the NCS program conducted or coordinated i
by the USEC Safety, Safeguards and Quality Manager. Internal audits of the NCS program shall be conducted in accordance with Section 2.18 of the QAP. The purpose of these audits is to determine the adequacy of the overall NCS program. This includes the adequacy of the NCSEs, NCSAs, internal surveillaces, and implementation of the NCS requirements.
NCS walk-throughs of facilities that may contain fissile material cperations are performed by NCS l
{
personnel to determine the adequacy of implementation of NCS requirements and to verify that conditions have not been altered to wivmely affect NCS. These walk-throughs are performed as specified by the NCS procedure on walk-throughs. For example, a walk-through inspection can be performed in response to trend da:a, at the request of the operations personnel, or due to concerns raised by employees or the i
NCS staff. As a minimum, these walk-throughs are completed for applicable areas biennially.
l 1
The results of these surveillances, audits, and walk-throughs are documented and reported to appropriate managers. Identified deficiencies are documented and corrected according to the problem reporting system described in Section 6.9 and the QAP Section 2.18.
NCS deficiencies are recorded and the data trended to monitor and prevent future violations.
Deficiencies are grouped into categories: building, organization / group, mass violation, volume violation, geometry violations, spacing violation, and unauthorized activities. Corrective actions are taken for adverse trends in accordance with the Quality Assurance Program.
5.2-9 L
r 8
SAR-PGDP PROPOSED RAC 98C108 (RO) 5.2.3 Technical Aspects j
5.2.3.1 Application of Parameters Moderation
' Water and oil are considered to be the most efficient moderators common'y found on the plant site.
_ When moderation is not controlled, either optimum moderation or worst credible moderation is assumed as l
. the normal case when performing analyses. When moderation is controlled, credible abnormal process upset conditions shall determine the worst case moderated conditions. For example, it has been determined that the l
' worst case moderation under process upset conditions for the oil in the Stokes-Pennwalt Pumps is an H/U ratio of 46.8. This value is based on the amount of uramum the oil can contain and still provide lubrication adequate for pump operation. The addition of more uranium will result in pump failure. Thus, the introduction of i
uranium into the pump oil is self-limiting.
Moderation control is applied to enrichment cascade equipment and product cylinders. Uranium enriched to 6 wt % or less,2"U is considered to be incapable of supporting a nuclear chain reacticn without the presence of moderation. The basis for this statement is provided in a NCSE.
The enriclunent cascade is a closed system designed to process gaseous UF.. This closed system prevents 6
the introduction of moderation due to wet air inleakage. Also because UF reacts chemically with moisture 6
(a moderator) to produce solid uranium-bearing compounds which impedes the proper operation of the cascade, the entire enrichment cascade is designed to minimize introduction of moisture. This includes the use of R-114 for coolant rather than water.
Moceration control is the primary NCS control for product cylinders and is based upon the ability of the gaseous diffusion plants to produce high punty UF (greater than or equal to 99.5 %). Assuming the remaining 6
L 0.5% impurity was composed entirely of HF, it would not provide sufficient moderation (i.e., atomic ration greater than 0.088 rUU) of the neutrons to sustsin a nuclear chain reaction. At the operating temperature and pressure ranges of the Product Withdrawal system hydrogen fluoride (HF) will not condense. This ensures the H/U ratio will remain below 0.088 since only a small, safe amount is dissolved in liquid UF.
The pressure in the product withdrawal system at PGDP is determined by the discharge pressure of the UF. product withdrawal (Normetex) pumps The C-310 Normetex pumps are equipped with a high discharge pressure system that will actuate the pump shutdown circuit at or below a pressure of 42 psia. Since the pump 1
will trip at or below a pressure of 42 psia, the HF cannot condense because it would have to be greater than 50 psia to do so. This enst.res moderation control and an atomic ratio below 0.088 in the product withdrawal system.
\\\\
t 5.2-10 l
I l
TSR-PGDP PROPOSED RAC 98C108 (RO)
~ SECTION 2.3 SPECIFIC TSRs FOR PRODUCT AND TAILS WITHDRAWAL FACILITIES i
2.3.2 SAFETY LIMITS 2.3.2.1 TEXT DELETED i
)
2.3.2.2 UF. CONDENSER COOLANT PRESSURE SL 2.3.2.2: C-310: UF condenser R-114 coolant pressure shall not exceed 220 psig C-315: UF. condenser R-ll4 coolant pressure shall not exceed 440 psig.
APPLICABILITY: Modes: All BASIS:
'Ihe UF. condensers in C-310 and C-315 withdrawal areas are designed and manufactured under ASME code regulations with a MAWP of 200 and 400 psig respectively [SAR Sections 3.4.3, 3.5.4, 4.3.3.1.2, and 4.3.4.1.2]. These pressure vessels were originally hydrostatically tested at 150 percent of the MAWP and are tested by nondestructive examination every five years to ensure their wall thicknesses meet or exceed the minimum wall thicknesses as specified by code. The safety limits are ultimately based on preserving the structuralintegrity of the UF. condensers. The ASME code requires that the pressure transient during relief l
from this type of vessel not exceed 110% of MAWP. Thus, the safety limit is established at 220 psig and 440 psig for the C-310 and C-315 UF condenser R-114 systems, respectively (110% of MAWP).
6 2.3-4
I 9
l*
TSR-PGDP PROPOSED j_
RAC 98C108 (RO) l l
SECTION 2.3 SPECIFIC TSRs FOR PRODUCT AND TAILS WITIIDRAWAL FACILITIES I
2.3.3 LIMITING CONTROL SE'ITINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES l
2.3.3.1 TEXT DELETED I
2.3-5
TSR-PGDP PROPOSED
.l RAC 98C108 (RO)
SECTION 2.3 SPECIFIC TSRs FOR PRODUCT AND TAILS WITIIDRAWAL FACILITIES 2.3.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES i
l 4
2.3-6
e GDP 98-0193 Page1of3 United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System Significance Determination The United States Enrichment Corporation (USEC) has reviewed the proposed changes associated with this certificate amendment request and provides the following Significance Determination for consideration.
1.
No Siunificant Decrease in the Effectiveness of the Plant's Safety. Safecuards or Security Programs The proposed SAR and TSR changes related to the Normetex High Discharge Pressure System (HDPS) have no effect on the plant's safety, safeguards or security programs contained in j
Volume 3 of the Application for United States Nuclear Regulatory Commission Certification for the Paducah Gaseous Diffusion Plant. Therefore, the effectiveness of these programs is unaffected by these changes.
2.
No Significant Change to Any Conditions to the Certificate of Comoliance None of the Conditions to the Certificate of Compliance for operation of the Paducah Gaseous Diffusion Plant specifically address the SAR and TSR requirements related to the Normetex HDPS. Thus, the proposed changes have no impact on any Condition to the Certificate of Compliance.
3.
No Significant Change to Any Condition of the Anoroved Comoliance Plan The HDPS, TSR 2.3.2.1, and TSR 2.3.3.1 do not impact any issue described in the Compliance Plan. The proposed deletion of these TSRs and revisions to the SAR do not change or invalidate any of the conditions of the approved Compliance Plan.
4.
No Significant Increase in the Probability of Occurrence or Consecuences of Previousiv Evaluated Accidents The accidents of concem are a release of UF to the atmosphere from the piping system on the 6
discharge side of the Normetex pump. The most likely failure point for a release in the system is the discharge bellows located between the pump and the discharge block valve. Presently, the HDPS is intended to function to prevent the integrity of the bellows from being challenged in the event that the discharge block valve closed on a running pump. Given the rate of pressure rise that occurs in this scenario and the pressure differential between the operating region and the present safety limit, it is not possible to configure the system to provide that
o*
e 4
GDP 98-0193 Page 2 0f 3 United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request l
Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump High Discharge Pressure System Significance Determination function. Consequently, the probability of a release due to rupture of the bellows will be increased over that previously evaluated in the SAR since the HDPS can not function to prevent a postulated failure mode. However, the consequences of a potential bellows mpture from discharge valve closure has been determined to result in a release of approximately 5 pounds j
of UF which will be confmed to the immediate area of release. This potential release is 6
bounded by the postulated fatigue failure of the bellows and subsequent 250 pound release that is analyzed in the S AR. Therefore, this change does not significantly increase the probability of occurrence or the consequences of previously evaluated accidents.
5.
No New or DifTerent Tvoe of Accident Deletion of the HDPS from the SAR accident analysis and TSRs does not create a new or different type of accident. Any potential failure due to the proposed changes would still be a failure of the pump discharge bellows which is described in the SAR.
6.
No Significant Reduction in Margins of Safety The proposed TSR and SAR changes delete an existing TSR safety limit and, thus, the margin of safety is also deleted. Although the plant physical configuration is not changed and, thus, no physical change to any margins are being made, the margin of safety as defined in the TSR is being eliminated. However, because the UF release detection safety system over the 6
Normetex pump would continue to detect the release should the bellows rupture, trip the pump, and close the block valves to terminate the release, no significant reduction in any margins of safety will result from the proposed TSR and SAR changes.
7.
No Significant Decrease in the Effectiveness of any Program or Plan Contained in the Certificate Aeolication The proposed SAR and TSR changes related to the Normetex HDPS have no effect on the plant's safety, safeguards or security programs contained in Volume 3 of the Application for United States Nuclear Regulatory Commission Certification for the Paducah Gaseous Diffusion Plant. Therefore, the efTectiveness of these programs is unaffected by these changes.
l l
T o
O GDP 98-0193 Page 3 of 3 United States Enrichment Corporation (USEC)
Proposed Certificate Amendment Request Safety Analysis Report, TSR 2.3.2.1, and TSR 2.3.3.1 Normetex Pump Iligh Discharge Pressure System Significance Determination 8.
The Pronosed Changes do not Result in Undue Risk to 1) Public Health and Safety. 2)
Common Defense and Security. and 3) the Environment.
The proposed changes will not result in undue risk to public health and safety. Potential accidents of concern are described in the SAR and only result in minor releases confined to the immediate area of release. In addition, the affected TSRs are not addressed in the plants safeguards or security programs or plans. Therefore, this proposed change does not result in undue risk to public health and safety, common defense and security, or the environment.
9.
No Change in the Tynes or Significant Increase in the Amounts of Anv Effluents that May be Released OfTsite This change has no effect on the generation or disposition of effluents. Therefore, this change does not change the type or amounts of efIluents that may be released offsite.
- 10. No Significant Increase in Individual or Cumulative Occuoational Radiation Exoosurg The proposed TSR and the Normetex HDPS change does not increase maintenance, testing, or operational requirements for the affected equipment. This change does not relate to controls used to minimize occupational radiation exposures. Therefore, there is no significant increase in individual or cumulative occupational radiation exposure.
I1. No Significant Construction Imoact This change does not involve a plant modification. Therefore, there is no significant construction impact,
- 12. No Significant Increase in the Potential for. or Radiological or Chemical Conseauences from.
Previousiv Analyzed Accidents The proposed changes will not result in an increase in individual or cumulative occupational radiation or chemical exposure. Any exposure from released UF is bounded by the SAR 6
analysis for failure of the Normetex discharge bellows As a result, the proposed changes do not result in a significant increase in the potential for, or radiological or chemical consequences from, previously evaluated accidents.