ML20217H673
| ML20217H673 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant, Paducah Gaseous Diffusion Plant |
| Issue date: | 04/21/1998 |
| 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-98-0078, GDP-98-78, TAC-L32043, TAC-L32044, NUDOCS 9804300033 | |
| Download: ML20217H673 (14) | |
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.o USEC
, A Global Energy Company April 21,1998 GDP 98-0078 Dr. Carl J. Paperiello Director, Office of Nuclear Material Safety and Safeguards Attention: Document 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
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cenificate amendment requests to Update the Application Safety Analysis Reports (SARUP) for the Paducah, Kentucky and Portsmouth, Ohio gaseous diffusion plants. provides USEC's responses to questions 1, 2, 3, 5, 6, 7, 9,16, and 18 from the referenced NRC letter. Additional time is required to complete the evaluations necessary to respond to Question 17. The response to this question will be submitted by May 1,1998.
l If you have any questions on USEC's responses, please call me at (301) 564-3250 or Steve Routh l
at (301) 564-3251. Enclosure 2 identifies new commitments contained in this submittal.
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Sincerely, n
l S. A.
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....~.. c v 3 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.
9804300033 980421
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pk 6903 Rockledge Drive, Bethesda, MD 20817-1818 Telephone 301-564-3200 Fax 301-564 320: F.np //www.usec.com Offices in Livermore, CA Paducah, KY Poc.ioudt, Oil Washington. DC
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Dr. Carl J. Paperiello
. April 21,1998 GDP 98-0078, 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 1,2,3,5,6,7,9,16, 18 i
- 2. Commitments Contained in this Submittal ec: Mr. Robert C. Pierson, NRC-liq NRC Region III NRC Resident Inspector - PGDP NRC Resident inspector - PGRTS Mr. Randall M. DeVault (DOE) 1 l
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l Enclosure I to GDP 98-0078 (11 pages total)
I Response to NRC Request for AdditionalInformation Concerning Paducah & Portsmouth Safety Analysis Report Update (TAC Nos. L32043 & L32044)
United States Enrichment Corporation Paducah and Portsmouth Gascous Diffusion Plants Docket Nos. 70-7001 and 70-7002 Responses to Questions 1,2,3,5,6,7,9,16,18 l
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j-SARUP Q&R - PGDP/ PORTS April 21,1998 r
l QI (NRC 2/25/98 Letter)
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l PGDP/ PORTS - General Comment The cover letters dated October 31,1997, states that information in tne SARUP (both Paducah and Portsmouth) involves an unreviewed safety question. It was recognized in the Compliance Plans that l
the SARUP would involve raising unreviewed safety questions based on the fact new criteria and methodologies would be used in the accident analysis chapter. The Compliance Plans provided a l
protocol for reporting significant safety issues in the Justification for Continued Operations. The 1
protocol required DOE to report to the NRC before transition if any significant safety issues were j.
identified in the SARUP process and after transition for USEC to follow 10 CFR 76.9(b) reporting for any safety significant issue, Enclosure 2 Item 4, of the SARUP cover letters identify significant increases in the probability of occurrences or consequences of previously evaluated accidents. The conclusions in those sections would appear to state that those events identified in Item 4 do not meet the "significant" threshold for reporting under 10 CFR 76.9(b). Provide more detail on: a) the events; b) the bases for those conclusions; c) the reason foi not reporting these events in accordance l
with the Compliance Plans and 10 CFR 76.9(b).
Response
l of the October 31,1997 SARUP submittal was prepared to provide sufficient information l
to assist the Director in determining, in accordance with 10 CFR 76.45, the significance of the SARUP j'
certificate amendment request. This enclosure was not intended, nor was this enclosure utilized, to establish the 10 CFR 76.9 reportability of safety significant issues which may have been identified as part of the SAR Update.-
l, Item 4, of the SARUP submittal did conclude that the SARUP submittal resulted in differences in the probability of occurrence and the consequences of previously evaluated accidents, j
liowever, as noted in the response to Enclosure 2, Item 4, of the SARUP submittal, this conclusion was l
based upon the use of evaluation criterL. and methodology significantly different from that employed in the l
current Application SAR. Therefore, based upon the use of different evaluation criteria and methodology, l
USEC conservatively concluded that the SARUP certificate amendment request resulted in significant l
differences in the probability of occurrence and the consequences of previously evaluated accidents.
The results of the SARUP accident analyses were compared to the comparable SAR accident scenarios. The results of this comparison concluded that there are no significant implications to public j.
health and safety or common defense and security. As such, reportability in accordance with the l
Compliance Plan and 10 CFR 76.9 is not required. This conclusion of no significant implication to public health and safety or common defense and security is consistent with the fact that DOE did not identify any significant implications for worker and/or public health and safety or common defense and security (with the exception of the seismic upgrades needed to PGDP process buildings C-331 and C-335), as regt. ired by Compliance Plan issue 2, in their February 14,1997 transmittal of the PGDP and PORTS site-wide Final Safety Analysis Reports and corresponding Safety Evaluation Reports.
SARUP Revision:
No revision required.
l SARUP Q&R - PGDP/ PORTS April 21,1998 Q2 (NRC 2/25/98 Letter)
PGDP/ PORTS - General Comment Technical Safety Requirement (TSR) Limiting Condition for Operation (LCO) selection criteria in Section 4.2.3 specifies that " limiting" initiating events are considered for the five criteria for TSR LCOs. However, Figures 4.2-2 and 4.3-1 imply that any initiating event whose threshold analysis exceeds evaluation guidelines (EGs) were also screened for the TSR LCO criteria. Were non-limiting events essential controls screened for TSR LCO selection?
Response
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Defining the limiting events required consideration of all actions made in response to each initiating l
event without any mitigative action. If an initiating event could result in a parameter change that might lead to an accident scenario which exceeds any evaluation guideline, this initiating event was a candidate for a limiting event. For each unmitigated initiating event that could lead to exceeding an EG, the following guidelines were used to dearmine the set of limiting events:
The initiating events which result in the most limiting change in a process parameter of interest for each frequency category was selected.
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If different facility protection methods were provided for the same proces? parameter of
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l interest, a limiting event for each frequency category, each parameter of interest, and each facility protection method was selected.
In other words, if any event required an essential control (and that control was not required for another limiting initiating event), then that event was also selected as a limiting initiating event. Based on this process, the controls necessary to meet the evaluation guidelines for any event were screened for TSR LCO selection because the events associated with those controls are, by definition, limiting initiating events.
SARUP Section 4.2.5.3 will be revised to clarify the above process.
SARUP Revision:
The first paragrapn in SARUP Section 4.2.5.3 will be revised to read as follows:
The objective of the accident selection portion of the hazard evaluation was to identify a representative set of events for accident analysis. This representative set of events is termed
" limiting initiating events" in the remainder of this analysis. Defining the limiting events required consideration of all actions made in response to each initiating event without any mitigative action. If an initiating event could result in a parameter change that might lead to an accident scenario which exceeds any EG, this initiating event is a candidate for a limiting event.
For each unmitigated initiating event that can lead to exceeding an EG, the following guidelines were used to determine the set of limiting events:
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.4' SARUP Q&R - PGDP/ PORTS April 21,1998 The initiating events which result in the most limiting change in a process parameter of l~
interest for each frequency category were selected.
If different facility protection methods were provided for the same process parameter of interest, a limiting event for each frequency category, each parameter of interest, and l
each facility protection method was selected.
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l SARUP Q&R - PGDP/ PORTS April 21,1998 Q3 (NRC 2/25/98 Letter)
PGDP/ PORTS - General Comment if not, were there non-limiting initiating events that had essential controls that met one of the five criteria listing in Section 4.2.37_(Refer to Question 1)
Response
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I These events were screened for TSR LCO selection in the SARUP as described in the response to Question Q2 (NRC 2/25/98 Letter).
SARUP Revision:
No revision required.
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SARUP Q&R - PGDP/ PORTS April 21,1998 Q5 (NRC 2/25/98 Letter)
PGDP/ PORTS - f4.3.2.1.5d Section 4.3.2.1.5 d., " comparison with guidelines" (page 4.3-53) notes that explosive concentrations of cascade gases could potentially result in a failure of the primary system.- TSR limits from USEC-01 and USEC-02 for preventing the explosive concentrations have been deleted in USEC SARUP.
Provide more basis for justifying deleting the TSR limits.
Response
Only PORTS currently has TSR limits for preventing explosive concentrations.
The TSR selection criteria (SARUP Section 4.2.3, criterion 3) requires a limiting condition for
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operation (LCO) for active SSCs that prevent or mitigate an event that could result in life threatening or
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serious health effects to onsite personnel from the release of radioactive materials. Explosive concentration limits for preventing coolant / oxidant exothermic reactions are administrative controls and not active SSCs.
i Therefore, TSR LCOs were not developed in the SARUP to address this event. Administrative controls regarding oxidant / coolant concentrations and prevention of exothermic reactions are implemented through operating procedures at both plants.
SARUP Revision:
l No revision required.
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SARUP Q&R - PGDP/ PORTS April 21,1998 Q6 (NRC 2/25/98 Letter)
PGDP/ PORTS - f4.3.2.1.6 Section 4.3.2.1.6, differs from POEF-LMES-89 in that the frequency was increased from Evaluation Basis Event (EBE) to Anticipated Event (AE) based on USEC SARUP not taking credit for cell coolant high pressure relief system. This was a limiting initiating event where a previous (USEC-01 and 02) TSR control has been deleted by accepting a higher frequency for the accident analysis.
Provide further justification for why accepting a higher frequency for an analyzed accident is an acceptable basis for deleting a TSR control.
Response
The event frequency for the coolant tube rupture into the primary system event was changed from an EBE to an AE based on the potential for a UF/ hot metal reaction to breach the coolant system (which has occurred). The coolant high-pressure relief system would afford no protection for the event ifit were to occur due to this mechanism. Therefore, no credit was taken for the system in order to assign a lower event frequency categorization. Accordingly, the control was not identified as an essential control, and j
no TSR LCO was identified. The event was therefore assigned to the AE frequency and the consequences of the event were evaluated accordingly. Based on the controls identified in SARUP Section 4.3.2.1.6, applicable evaluation guidelines would be met.
As discussed in SARUP Section 3.15.3.4 (Paducah) and 3.8.3.4 (Portsmouth), the coolant high pressure relief system was identified as an AQ SSC due to its potential role in providing local personnel
_ protection if the coolant tube rupture event were the result of a coolant over pressurization mechanism.
However, the coolant high pressure relief system is not an active SSC and, therefore, it does not satisfy the TSR LCO selection criteria (SARUP Section 4.2.3, criterion 3).
SARUP Revision:
No revision required.
SARUP Q&R - PGDP/ PORTS April 21,1998 4
Q7 (NRC 2/25/98 Letter) 10DP/ PORTS - 04.3.2.2.2a Section 4.3.2.2.2 a., " scenario description" identifies the 5% ullage as the ANSI limit that protects cylinders from hydraulic rupture when heated to normal autoclave temperatures. Based on that scenario, a TSR safety limit for cylinders was identified. Other factors that protect the cylinder from hydraulic mpture such as fill limits and cold pressure checks were identified as administrative controls that were previous (USEC-01 and 02) TSR limits. The other factors appear to preserve initial conditions for an accident scenario that could have serious off-site consequences. Provide further justification for not identifying cold pressure checks and cylinder fill limits as TSR limits.
Response
The current TSR requirements regarding cylinder high pressure and high temperature include LCOs for verification of cylinder weight versus fill limits based on cylinder classification and the performaxe of a cold pressure check. Although these administrative controls are not specifically stated in the SARUP TSRs, they are identified as essential controls in SARUP Chapter 4 and would be required to be performed
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in order to meet SARUP TSR Section 1.2.7 relative to classifying cylinders for heating.
t Until cylinders are being heated, there is no safety issue involved. As discussed in SARUP sections 4.3.2.2.6 and 4.3.2.2.7, the high cylinder pressure system is a TSR LCO control that is also available to l
minimize the potential for cylinder rupture by tripping the steam supply prior to reaching the M AWP of the cylinder.
SARUP Revision:
No revision required.
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SARUP Q&R - PGDP/ PORTS April 21,1998 Q9 (NRC 2/25/98 Letter)
PGDP/ PORTS - $4.3.2.2.4 l
Section 4.3.2.2.4, states a concern about transient events while the autoclave facility is evacuated and I
then states that four hours is a reasonable time frame to allow a return time from a facility evacuation.
Provide further bases for the four hour time frame with more detail about the nature of the transient events.-
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Response
1 This event analyzes evacuation of the UF. handling and storage facilities to ensure that adequate controls are in place so that evacuation does not result in consequences from process operations. The scenario assumes that the facility is operating normally when the evacuation is initiated. The evacuation J
is caused by an event other than a release of hazardous material in the facility (e.g., because of a spurious alarm). The types of transient events during the evacuation scenario that are of concern are the initiating l
events described elsewhere in SARUP Chapter 4 that could occur without operator presence (e.g., Section l-4.3.2.2 - autoclave steam control valve fails open, Section 4.3.2.2.6 - heating of a cylinder with excessive UF).
6 The Paducah evacuation event does not take credit for the four hour period.
The Portsmouth evacuation event does take credit for the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> time period. During a facility evacuation, the autoclave "Q" and "AQ" SSCs and TSRs provide adequate protection against autoclave process transients because no operator actions are required to initiate those systems during heating cycles.
i The potential initiators due to human actions do not apply since no one is present and those potential initiators during the evacuation process are addressed in the accident analysis with essential controls identified. The only remaining concerns during an evacuation would be the potential passive failure of "Q"
. SSCs with no external initiating event. These are considered to be of low probability due to the quality controls imposed on the SSCs involved. For these events, four hours was assessed to be a reasonable time-frame for the building to be cleared for reentry. In the event of a facility evacuation due to an accident in the facility, the emergency response program implementation would determine -what compensatory measures regarding facility operations would be taken. For example, all autoclave heating i
operations can be halted by valving off the steam header supplying the facility.
SARUP Revision:
No revision required.
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SARUP Q&R - PGDP/ PORTS April 21,1998 Qi6 INRC 2/25/98 Letter)
PGDP/ PORTS - 54.3.2.2.15
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For Section 4.3.2.2.15, " Cylinder Failure Outside Autoclave," why is the cylinder high temperature steam cutoff identified as an essential control?
Response
An initial condition of the source term / consequence analysis is that the UF in the cylinder (when i
dropped) is at 240 F, which corresponds to a saturated steam pressure of 10 psig. The autoclave steam pressure control system (Paducah) and the cylinder high temperature steam cutoff system (Portsmouth) ensure that the UF. cylinder temperature will not exceed this assumed initial condition by isolating the steam supply at 10 psig. Although the temperature in the cylinder, if dropped outside the autoclave, will be less 6an this maximum temperature, these systems do preserve the initial condition that the temperature will be no greater than 240 F.
SARUP Revision:
No revision required.
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Q18 (NRC 2/25/98 Letter)
PGDP/ PORTS - TSR 2.1.1 TSR 2.1.1 Operational Modes for the Cascade Facilities identifies the Mode " Controlled Feeding."
Initial Certification efforts identified that mode as an unanalyzed mode at Paducah. In addition, concerns were raised by a hydraulic rupture of a feed line in December 1994 during such an evolution. It was determined that the Controlled Feeding mode was unauthorized at Paducah until a basis for the mode was provided. Provide that basis.
Response
4 The SARUP analysis of this mode is contained in the applicable Plant Safety Operational Analyses (PSOAS) for the feed and toll transfer facilities. Copies of these documents are available at the site for review.
This mode was analyzed in the same manner as the other operational modes (e.g., Hazard Identification, Identifying Initiating Events, Process Hazard Analysis (PrHA), and a PSOA) that resulted.
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in essential controls (e.g., high cylinder pressure system, UF. cylinders [ passive], criticality accident alarm system, UF. primary system outside autoclave, autoclave primary containment system) being identified
- with TSRs that prevent and/or mitigate consequences of any UF. release. Events analyzed during this mode of operation were within applicable EGs.
SARUP Revision:
~ No revision required.
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l GDP 98-0078 Page1ofI Commitments Contained in This Submittal 1.
The first paragraph in SARUP Section 4.2.5.3 will be revised to read as follows:
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i The objective of the accident selection portion of the hazard evaluation was to identify a representative set of events for accident analysis. This l
representative set of events is termed " limiting initiating events" in the remainder of this analysis.
Defining the limiting events required consideration of all actions made in response to each initiating event without any mitigative action. If an initiating event could result in a i
parameter change that might lead to an accident scenario which exceeds any EG, this initiating event is a candidate for a limiting event. For each 3
l-unmitigated initiating event that can lead to exceeding an EG, the following guidelines were used to determine the set of limiting events:
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The initiating events which result in the most limiting change in a process parameter of interest for each frequency category were selected.
I If different facility protection methods were provided for the same process parameter of interest, a limiting event for each frequency category, each parameter of interest, and each facility protection method was selected.
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Additional time is required to complete the evaluations necessary to respond to Question 17.
The response to this question will be submitted by May 1.1998, i
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