ML20217J287
| ML20217J287 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant, Paducah Gaseous Diffusion Plant |
| Issue date: | 03/27/1998 |
| 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-98-0058, GDP-98-58, TAC-L32043, TAC-L32044, NUDOCS 9804060257 | |
| Download: ML20217J287 (13) | |
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USEC A Global Energy Company March 27,1998 GDP 98-0058 l
'3 Dr. Carl J. Paperiello Director, Office of Nuclear Material Safety and Safeguards Attention: Doc'unent Control Desk United States Nuclear Regulatory Commission Washington, DC 20555-0001 Paducah Gaseous Diffusion Plant (PGDP)
. Portsmouth Gaseous Diffusion Plant (PORTS)
Docket Nos. 70-7001 & 70-7002 Response to NRC Request for AdditionalInformation (TAC NOS. L32043 & L32044)
Dear Dr. Paperiello:
By letter dated February 25,1998 (see the reference), the U.S. Nuclear Regulatory Commission (NRC) forwarded to the United States Enrichment Corporation (USEC) various questions on the certificate amendment requests to Update the Application Safety Analysis Reports (SARUP) for the
'I Paducah, Kentucky and Portsmouth, Ohio gaseous diffusion plants.
f provides USEC's responses to questions 4,8,10,11,12,13,14,15, and 19 from the referenced NRC letter. Further evaluations are required to complete the responses to the remaining j
questions. The responses to the remaining questions will be submitted by April 21,1998.
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if you have any questions on USEC's responses, please call me at (301) 564-3250 or Steve Routh at (301) 564-3251. Commitments contained in this submittal are identified in Enclosure 2.
' Sincerely, A
IS. A. I J Steven A. Toelle Nuclear Regulatory Assurance and Policy Manager
Reference:
Letter from Charles Cox (NRC) to Mr. James H. Miller (USEC), Paducah and Portsmouth Certificate Amendment Requests-Update the Application Safety Analysis
. (TAC Nos. L32043 & L32044), dated February 25,1998.
9804060257 990327 i
PDR ADOCK 07007001 C
PDR m
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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
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- Dr. Carl J. Paperiello
- Ma'rch 27,'1998 GDP 98-0058, Page 2
Enclosures:
- 1. Response.to NRC Request for Additional Information Concerning Paducah Safety Analysis Report Update (TAC Nos. L32043 & L32044), United States Enrichment Corporation, Paducah and Portsmouth Gaseous Diffusion Plants, Docket Nos. 70-7001 and 70-7002, Responses to Questions 4,7, 8,9,10,11,12, t
13,14,15,19
- 2. Commitments Contained in this Submittal cc: Mr. Robert C. Pierson, NRC-HQ NRC RegionIII NRC Resident Inspector-PGDP NRC Resident Inspector - PORTS Mr. Randall M. DeVault (DOE).
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Enclosure I to GDP 98-0058 (10 pages total)
Response to NRC Request for AdditionalInformation Concerning Paducah & Portsmouth Safety Analysis Report Update (TAC Nos. L32043 & L32044)
United States Enrichment Corporation Paducah and Portsmouth Gaseous Diffusion Plants Docket Nos. 70-7001 and 70-7002 i
Responses to Questions 4,8,10,11,12,13,14,15,19~
SARUP Q&R - PGDP/ PORTS March 27,1998
' Q4 (NRC 2/25/98 Letter)
PGDP/ PORTS - 54.3.2.1.3c Section 4.3.2.1.3 c., " consequence analysis" for operational personnel in the Area Control Room (ACR) (page 4.3-47) refers to an evaluation that concluded adeauate time was available for operators to perform required actions. Identify that evaluation.
Response
The evaluation reference is as follows: Kim et. al., Dispersion of UOA Aerosol and HF Vapor in the Operating FloorDuring Winter Ventilation at the Paducah Gaseous Difusion Plant, ORNL/TM-13287, i /30/%, Oak Ridge National Laboratory, Oak Ridge, Tennessee. A copy of the evaluation is available at the sites for review.
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This evaluation calculated that it would take approximately 400 seconds for vapor and aerosol associated with a 130 lb/sec release to be transported to the control room.. Based on the time periods within which mitigation is required (i.e.,90 seconds for the B-stream block valve closure event, and 240 seconds for the large UF release to atmosphere event), there is adequate time to perform the 6
associated mitigative actions l
This evaluation was applied to PORTS as well, based on the similarity of the ventilation design and flow patterns.
SARUP Revision:
No revision required.
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SARUP Q&R - PGDP/ PORTS March 27,1998 Q8 (NRC 2/25/98 Letter)
PGDP/ PORTS '- 54.3.2.2.2 Section 4.3.2.2.2, does not go into a source term nor consequence analysis based on a conclusion that adequate protection is available to prevent prunary system failure. This is not consistent with the other limiting initiating events where similar conclusions still resulted in a source term and consequence analysis. Provide furtherjustification or provide a source term and consequence analysis.
Response
This event (autoclave steam control valve fails open) was evaluated as an AE with no resulting source terms and consequences. The essential controis identified maintain primary system pressure l within EG3, thus precluding any release of UF. For a UF. release to be caused by the steam valve failing open, two, preventive systems classified as impoitant to safety would also have to fail. (These systems are the autoclave steam pressure control and autoclave high pressure isolation systems at Paducah, and the UF. cylinder high temperature steam cutoff and autoclave shell high pressure containment systems at Portsmouth.) This is not the case for the other limiting initiating events that required a source term and consequence analysis.
SARUP Revision:
No revision required.
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SARUP Q&R - PGDP/ PORTS March 27,1998 Q10 (NRC 2/25/98 Letter)
PORTS - 64.3.2.2.10 (PORTS only) Section 4.3.2.2.10 a., discusses administrative controls that prevent pigtail failure. One such control is that cylinders are not rolled in an open autoclave unless visual contact is made during the rolling process. That practice has led to kinkmg of pigtails on 2.5 ton cylinders. The Paducah practice is to remove the pigtails before rolling. What operating constraints necessitate keeping the pigtails attached at PORTS resulting in possible challenges to the primary system integrity of the pigtails?
Response
At PORTS, it has been a long standing operational practice to loosen, but not disconnect, pigtails during most cylinder rolling operations to mimmize the number of pigtail connections and disconnections. While this approach is not considered an." operational constraint," it is considered
. safe and not a challenge to primary system integrity. The cylinder is rolled only when the pigtail is empty and the cylinder is isolated from the pigtail. As such, there is no challenge ta the primary system integrity during rolling operations. If a pigtail is damaged during such evolutions, it is disconnected and another pigtail is installed prior to continuing operations. Procedures require operators to observe the pigtail during such operations and to remove the pigtail if any damage i; observed. Prior to the introduction of UF., the pigtail is re-tightened and a leak test is performed.
This would identify any pigtail damage prior to introduction of UF..
SARUP Revision:
No revision required.
SARUP Q&R - PGDP/ PORTS March 27,1998 Q11 (NRC 2/25/98 Letter)
' PGDP/ PORTS - 64.3.2.2.10 Section 4.3.2.2.10, states that past pigtail failures have identified administrative controls that make future events improbable and, therefore, the frequency of the analyzed accident is reduced to EBE (multiple personnel errors unlikely). Similar statements are made in the drop cylinder scenario. In light of actual personnel performance, is the EBE event frequency a good assumption? What would be the results of an operational analysis of this scenario assuming a higher frequency for this event?
Response
Although pigtail failures have occurred in the past, the administrative controls listed in the scenario description were implemented as a result of these failures to reduce the probability of occurrence of this event. Plant experience since these changes were implemented indicate that these j
administrative controls are effective. (These controls have been in place for over 15 years. During that time there have been no pigtail /line failures.) As noted in the scenario description, it would require multiple operator errors and/or passive equipment (Q SSC) failures in order for this event to occur. If the event were classified as an AE event frequency, the operational analysis would be unaffected because all available administrative and engineered controls were considered and evaluated in the existing operational analysis. The evaluated consequences would remain the same.
I SAMUP Revision:
No revision required.
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l SARUP Q&R - PGDP/ PORTS March 27,1998 Q12 (NRC 2/25/98 Letter) '
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' PGDP/ PORTS - 54.2.2.10b l
Section 4.2.2.10 b., " source term analysis" assumes a 45 second release both for PORTS and Paducah. Paducah has an automatic pigtail isolation system at the transfer station while PORTS relies on operator action. Why is the 45 second release time applicable to both sites?
Response
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- In the Paducah analysis, it was assumed that the UF. release detection system would actuate l-
.within 15 seconds and the valve would close in an additional 30 seconds. The proximity of the UF.
- release detector and historical system performance during surveillance testing provide confidence that
- the system will initiate valve closure within 15 seconds, i
In the Portsmouth analysis, it was assumed that the operator would identify (sight and/or smell) the UF. release within 15 seconds since the accident scenario identifies accident initiators as being due i
to operator actions (e.g., hitting lines with a crane load or another operator error). Therefore, the operator would be in the area and involved in operations potentially impacting the UF. system and would manually initiate valve closure upon exiting of the facility, which shuts the valve in an additional 30 seconds. Such a release would be readily identified and autoclave isolation switches are located at the building exits to assure accessibility in the event of a release.
l In addition, the consequence evaluation (SARUP Section 4.3.2.2.10 c.) for both sites showed that system isolation would occut well within the time required in order to meet the offsite EGs.
SARUP Revision:
No revision required.
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~ SARUP Q&R - PGDP/ PORTS March 27,1998 Q13 (NRC 2/25/98 Letter)
PGDP/ PORTS - 64.2.2.10b
- Section 4.2.2.10 b., " source term analysis" release rates for Paducah and PORTS are'the same even though there are identified differences in system equipment that would call this into question. Provide more detail on the basis of the release rate. Examples might include the assumed size of the daughter cylinders (2.5 ton cylinder would appear to be the size assumed but 10 ton cylinders are sometimes used at the X-344A at PORTS) and why different piping and pigtail diameters have the same release rate (most limiting chosen for both sites)?
Response
~'A source term analysis evaluated both PGDP and PORTS cylinder comb'mations and facility unique piping configurations. A single consequence analysis was used for both PORTS and PGDP, using the higher discharge rater from PORTS from the source term analysis, but the smaller withdrawal building at PGDP for building wake effects. This provided conservative consequences for both PORTS and PGDP and with the offsite receptors at both sites being approximately the same distance, the same results are reflected for both facilities.
SARUP Revision:
No revision required.
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SARUP Q&R - PGDP/ PORTS March 27,1998 Q14 (NRC 2/25/98 Letter)
PGDP/ PORTS - 54.2.2.11b Section 4.2.2.11 b., " source term analysis" assumes 45 second release rate based on 15 second detection and 30 second closure. The 30 second closure time is not captured in pigtail isolation TSR surveillance for the manual pigtail isolation checks. Provide basis.
Response
1 The withdrawal station isolation system at PGDP (see SARUP TSR 2.3.3.1) and the pigtail line isolation system at PORTS (see SARUP TSR 2.3.3.1) are used to close appropriate isolation valves in the event of a pigtail failure in the withdrawal facilities. These systems have both automatic (via
" smoke" detectors) and manual (via pushbuttons) means of activation. Channel functional tests performed for the automatic means of activation for these systems ensure the appropriate control valves close within 30 seconds after system activation (i.e., detection). A separate surveillance requirement is performed at each plant to ensure the manual isolation button for the systems are operational. It is not necessary to verify valve closure time twice since both actuation methods close the same set of valves.
SARUP Revision:
No revision required.
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- SARUP Q&R-PGDP/ PORTS March 27,1998
- Q15 (NRC 2/25/98 Letter)-
.I PGDP/ PORTS - TSR General Comment (Paducah Only) Faducah deleted the smoke detectors as a TSR LCO for the backup centrifugal I
compressors at Tails Withdrawal (USEC-01) from the TSR LCOs in the SARUP. Provide :
- basis.
Response
The smoke detection system associated with the backup centrifugal compressors in the tails withdrawal facility only provides an alarm after a UF release has occurred. Since this detection -
system does not provide any active preventive or mitigative (other than alarm) functions, the SARUP --
accident analyses evaluating failures of the high-speed withdrawal compressors (see Sections 4.3.2.2.1 and 4.3.2.2.12) credited the motor load indicators for providing an indication of abnormal compressor j
operation that could lead to failure. The indication of abnormal operation provided by the motor load indicators would typically enable corrective action to be taken prior to primary system failure. ' If -
compressor failure did occur, consequence analysis of an unmitigated release indicated that off-site evaluation guidelines would not be exceeded for the event.
SARUP Revision:
4 No revision required.
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SARUP Q&R - PGDP/ PORTS March 27,1998 Q19 (NRC 2/25/98 Letter)
PGDP/ PORTS -TSR 2.1.3.1 and 2.1.3.2 TSR 2.1.3.1 and 2.1.3.2 for compressor motor trip and load identifies that the TSR is only applicable for "000" and "00" compressors. The smaller centrifugal compressors can have a hot metal reaction (see withdrawal station accident scenario). Are these compressors not considered for TSR application due to not being limiting initiating events (see question 1)? Can they result in a release that meets criteria 3 for TSR LCO selecuon?
Response
These smaller compressors were considered for TSR application through evaluation of the applicable limiting events in SARUP Section 4.3.2 (e.g., compressor failure /UF. hot metal reaction),
and further system evaluation in SARUP Section 3.8 (Portsmouth)/3.15 (Paducah).
The only smaller compressors whose failure could result in a release that meets criterion 3 for -
TSR LCO selection are the interbuilding booster compressors associated with the "00" and "000" compressors. These compressors can operate above atmospheric pressure. Credit was taken (in SARUP Sections 3.8.3.1 and 3.8.3.6 (Portsmouth) and 3.15.3.1 and 3.15.3.6 (Paducah) for detecting.
and mitigating failures associated with booster compressors by the motor load and trip system for the
- adjacent enrichment cell compressor motors. Also, as described in the referenced SARUP Sections 3.8 (Portsmouth) and 3.15 (Paducah), failures in smaller enrichment and purge compressors would not
- meet criterion 3 for TSR selection because the amount of UF. material at risk is small, and this equipment operates below atmospheric pressure. The exposure of workers within the building from any releases from these compressors would be minimized by evacuation and would preclude exceeding the PSOA onsite thresholds. Therefore, only the "00" ard "000" enrichment cell compressor motor -
systems are included in the applicability statements of SARUP TSRs 2.1.3.1 and 2.1.3.2.
SARUP Revision:
.No revision required.
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GDP 98-0058 Page1ofI Commitments Contained in this Submittal 1.
Responses to questions 1,2,3, 5,6,7,9,16,17, and 18 on the SARUP submittal from the NRC's February 25,1998 letter will be submitted by April 21,1998.
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