ML20217P508
| ML20217P508 | |
| Person / Time | |
|---|---|
| Site: | Paducah Gaseous Diffusion Plant |
| Issue date: | 02/27/1998 |
| 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-98-0036, GDP-98-36, TAC-L32057, NUDOCS 9803100299 | |
| Download: ML20217P508 (6) | |
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V d USEC A Global Energy Company February 27,1998 GDP 98-0036 Dr. Carl J. Pcperiello Director, Of6ce of Nuclear Material Safety and Safeguards Attention: Document Control Desk l
U.S. Nuclear Regulatory Commission Washington, D.C. 20555 0001
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Paducah Gaseous Diffusion Plant (PGDP)
I Docket No. 70-7001 Request for Enforcement Discretion - Response to NRC Request for Additional Information (TAC No. L32057)
Dear Dr. Paperiello:
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' On February 25,1998, USEC requested enforcement discretion associated with the potential
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consequences of postulated seismically-induced failures in the liquid withdrawal facilities (USEC letter GDP 98-0031). NRC letter dated February 26,1998, (TAC No. L32057) submitted questions regarding this response and USEC's response by close of business on February 27, 1997. Per your request, Enclosuie 1 to this letter is USEC's response to the NRC questions.
i Should you have any questions regarding this matter, please contact Larry Jackson at j
(502)441-6796. Commitments contained in this submittal are identified in Encicsure 2.
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l Sincerely, pf~fy
- s. A.
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Steven A.Toelle Nuclear Regulatory Assurance and Policy Manager
Enclosures:
1.
USEC Response to NRC Request for Additional Information dated February 26,1998, 2.
List of Commitments cc: NRC Document Control Desk
- NRC Region III Office ggg ggggg NRC Resident Inspector-PGDP
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Mr. Robert C. Pierson (NRC)
Mr. Randall M. DeVault (DOE) 6903 Rockledge Drive. Bethesda, MD 20817-1818 f;,g Telephone 301-564-3200 Fax 301-564-3201 http://www.usec.com 9903100299 96f32i7 '
'~ Paducah, KY Portsmouth. Oil Wahington, DC PDR ADOCK 07007001 C
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GDP 98-0036 j
Page 1 of 4 Response to NRC Request for AdditionalInformation Paducah Request for Enforcement Discretion NRC Comment #1 Propored Commitments do not include a commitment to control and minimize at all times the UF6 I
inventory in the C-315 online accumulator. As proposed the limit is effectively the full volume of 4
the accumulator.
1 USEC Response Accumulators are primarily used in the interim process when a cylinder has been disconnected and another cylinder is waiting to be connected. During the evolution of switching from one cylinder j
to another, Qe liquid UF6 is diverted to the accumulator for less than one hour which typically results in less than 5000 lb being temporarily diverted to the accumulator. This inventory is quickly emptied once liquid flow is reestablished to the new cylinder. Other routine conditions resulting in temporary use of the accumulators include: 1) difficulties in re-establishing flow which could delay resumption of cylinder filling when valving in the new cylinder; 2) surveillance activitics which 1
require ell cylinder fill positions to be removed from service; and 3) other operational problems which can delay resumption of normal cylinder filling for up to several hours. More prolonged accumulator filling is infrequent and typically a result of either fill position or crane inoperability.
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In addition to the compensatory actions that were described in the Justification for Continued Operation (Enclosure 2 to GDP 98-0031), 'J3EC is taking the following additional actions to minimize accumulator inventory in C-315:
The Plant Shift Superintendent (PSS) will be notified once material is diverted to the accumulators for greater than 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. At that time, the amount of material being stored in the accumulator will be tracked using calculated withdrawal rates. The PSS will initiate high priority actions for timely resolution of problems requiring accumulator use. At typical withdrawal rates, this will result in action being taken at approximately 10,000 lb. in the accumubtor.
The PSS must grant approval prior to the calculated accumulator contents exceeding 28,000 lb.
Steps will be taken to minimize withdrawal rates by making appropriate cascade adjustments.
(Normal C-315 withdrawal operations would result in accumulator contents ofless than 28,000 lbs.)
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GDP 98-0036 Page 2 of 4 Recycle opetations will be initiated prior to complete filling of the accumulator if recycle appears inevitable.
- Long term orders have been issued to implement these actions.
NRC Comment # 2 i
No compensatory actions are proposed for limiting accumulator inventory in Building C-310/C-310A (purge and product withdrawal building). This is supposedly based on low probability of'
- having inventory present. That is an unacceptable basis given the supporting information in the j
. JCO. Must propose lim.its and a mechanism to ensure that these limits are adhered.
USEC Response Accumulators are primarily used in the interim process when a cylinder has been disconnected and I
. another cylinder is waiting to be connected. During the evolution of switching from one cylinder to another, the liquid UF6 is diverted to the accumulator for less than one hour.which typically j
results in less than 5000 lb being temporarily diverted to the accumulator. This inventory is quickly l
emptied once liquid flow is reestablished to,9 new cylinder. Other routine conditions resulting in J
temporary use of the accumulators include: 1) difficulties in re-establishing flow which could delay resumption of cylinder filling when valving in the new cylinder; 2) surveillance activities which require all cylinder fill positions to be removed from service; and 3) other operational problems which can delay resumption of normal cylinder filling for up to several hours. More prolonged accumulator filling is infrequent and typically a result of either fill position or crane inoperability.
I In addition to the compensatory actions that were described in the Justification for Continued Operation (Enclosure 2 to GDP 98-0031), USEC is taking the following additional actions to minimize accumulator inventory in C-315:
The PSS will be notified once material is diverted to the accumulators for greater than 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
At that time the amount of material being stored in the accumulator will be tracked using
- calculated withdrawal rates. The PSS will initiate high priority actions for timely resolution of problems requiring accumulator use. At typical withdrawal rates, this will result in action being taken at approximately 4,000 lb. m the accumulator.
The PSS must grant approval prior to the calculated accumulater contents exceeding 12,000 lb.
Due to concerns with product assay control, no steps will generally be available to minimize withdrawal rates, but the PSS and Cascade Coordinator will continue to evaluate options while fill levels are above 12,000 lb. As previously stated, normal C-310 withdrawal operations
- infrequently result in accumulator contents greater than 12,000 lb.
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Y GDP 98-0036 I
Page 3 of 4 Recycle operations will be initiated prior to complete filling of the accumulator if recycle appears inevitable.
Long term orders have been issued to implement these actions.
NRC Comment # 3 Provide information about the habitability of C-300 USEC response There are no specific habitability requirements for C-300. C-300 is the backup facility for the ACRs for the shut down of equipment. Should C-300 become inhabitable, the cascade facilities can be-shutdown from alternate locations.
The C-300 Central Control Facility is capable of withstanding the plant's seismic event of.15g.
Seismic switches from the '00' buildings alarm in C-300 to warn the Central Control Facility operator of seismic activity that could result in shutting the cascade down. Also, displacement units in the '000' buildings alarm in C-300 and procedures require action to determine if cascade damage has occurred. Within two minutes of the initiation of the seismic event, an order for cell shutdown comes from the Plant Shift Superintendent or the Cascade Coordinator. A cascade shutdown will occur within eight minutes of the earthquake initiation.
C-300 is located approximately 270' west of C-310 and 1550' west of C-315. The prevailing wind direction for the Plant pe' SAR Figure 2.3.1 is from the south-southwest. Easterly winds, directly from C-315 and C-310 toward C-300 occur approximately 3 percent of the time. During a UF6 release, the Incident Commander or the Crisis Manager prescribe protective actions which may include alerting, evacuation and assembly, or sheltering in place (SAR 5.4.1). C-300 operating personnel would normally be sheltered in C-300 by the building structure during the performance of their required actions.
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GDP 98-0036 Page 4 of 4 NRC Comment # 4 of the JCO states that the accumulators fail at less than 0.05g. JCO assumes that they fail at 0.05g. Please clarify which is correct.
USEC Response 1
The JCO is correct as written. Further explanation is provided below:
The High Confidence of Low Probability of Failure (HCLPF) capacity for accumulator anchorage determined in the design analysis calculations supporting the JCO Appendix A Tables is 0.02g. This represents the capacity for which there is 95% confidence ofless than a 5% chance of failure. The '
. HCLPF capacity is "zell below the earthquake magnitude that would cause the average piece of equipment to fail. The median capacity, the earthquake magnitude that would cause halfof a sample to fail, is about 2.5 times the HCLPF capacity for typical equipment. Earthquake experience data I
suggest that damage does not occur for peak ground accelerations s; 0.05g. Additionally, the accuracy of seismic calculations does not support assigning capacities below 0.05g. Therefore, the use of 0.05g in the probability argument is supported.
The 0.02g IfCLPF capacity for the accumulators is the value at which the anchor bolts begin to be pulled out of the concrete floor. Significant movement would then be required to either rupture the vessel or to break the attached piping. Thus, a UF release would not be expected below 0.05g.
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GDP 98-xxxx i
Page1ofI LIST OF COMMITMENTS l
1.
Additional actions to minimize accumulator inventory in C-315 are as follows:
The Plant Shift Superintendent (PSS) will be notified once material is diverted to the r.ccumulators for greater than 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. At that time, the amount of material being stored in the accumulator will be tracked using calculated withdrawal rates. The PSS will initiate high priority actions for timely resolution of problems requiring accumulator use. At typical withdrawal rates, this will result in action being taken at approximately 10,000 lb. in the accumulator.
The PSS must grant approval prior to the calculated accumulator contents exceeding i
28,000 lb. Steps will be taken to minimize withdrawal rates by making appropriate cascade adjustments.
Recycle operations will be initiated prior to complete filling of the accumulator if recycle appears inevitable.
2.
Additional actions to minimize accumulator inventory in C-310 are as follows:
The PSS will be notified once material is diverted to the accumulators for greater than 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. At that time the amount of material being stored in the accumulator will be tracked using calculated withdrawal rates. The PSS will initiate high priority actions for timely resolution of problems requiring accumulator use. / < typical withdrawal rates, this will result in action being taken at approximately 4,000 lb. in the accumulator.
The PSS must grant approval prior to the calculated accumulator contents exceeding 12,000 lb. Due to concerns with product assay control, no steps will generally be available to minimize withdrawal rates, but the PSS and Cascade Coordinator will continue to evaluate options while fill levels are above 12,000 lb.
Recycle operations will be initiated prior to complete filling of the accumulator if recycle appears inevitable.