ML20237B934
| ML20237B934 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 08/14/1998 |
| From: | Toelle S UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | Pierson R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| GDP-98-0178, GDP-98-178, TAC-L32012, NUDOCS 9808200102 | |
| Download: ML20237B934 (12) | |
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l USEC 1
, a ciob.: snusy company August 14,1998 1
GDP 98-0178 Mr. Robert C. Pierson Chief, Special Projects Branch Division of Fuel Cycle Safety and Safeguards, NMSS U.S. Nuclear Regulato.y Commission Washington, D.C. 20555-0001 Portsmouth Gascous Diffusion Plant (PORTS)
Docket No. 70-7002 Response to Request for AdditionalInformation -Compliance Plan Issue 3, Action 9, ASME Code Interpretation and Assessment Results,(TAC NO. L32012)
Dear Mr. Piersan:
The purpose of this letter is to provide a response to the United States Nuclear Regulatory Commission's (NRC) request (TAC No. L32012) for additional information on Compliance Plan Issue 3, Action 9, ASME Code Interpretation and Assessment Results. The request for additional information was provided to the United States Enrichment Corporation (USEC) in Reference 1 and identified additional infonnation required by NRC to review USEC's submittal (Reference 2) related to Compliance Plan Issue 3, Action 9. Enclosure 1 to this letter provides PORTS' response to this request for additional information.
USEC determined that the ASME Code Committee had previously issued Code Case Number 2211 (Enclosure 2) and that this Code Case applies to Compliance Plan Issue 3, Action 9. This Code Case specifically addresses the conditions which must be satisfied in order for a pressure vessel to be f
provided with overpressure protection by system design in lieu of a pressure relief device. The j
enclosed response demonstrates PORTS' compliance with this Code Case. Additional evaluation I
to determine the applicability of this Code Case to the Paducah Gaseous Diffusion Plant (PGDP) is required. A PGDP specific response to this request for additional information will be provided by
' August 21,1998.
k If you have any questions or require additional infonnation, please contact Mark Smith at (301) 564-3244. Commitments contained in this submittal are identified in Enclosure 3.
Sincerely,
/]
S. 9.
I Steven A.Toelle Nuclear Regulatory Assurance & Policy Manager 9008200102 990614 rive. Bethesda. MD 20817-1818 s eicpnone 5vi- >we-xou Fax 301-564-3201 httpAww.usec.com OfTices in Livermore. CA Paducah, KY Portsmouth. OH Washington. DC l
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Mr,. Robed C. Pierson August 14,1998 -
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GDP _98-0178, Page 2
Enclosures:
1.
Response to Request for Additional Information -Compliance Plan Issue 3, Action 9, ASME Code Interpretation and Assessment Results, (TAC NO.
L32012) 2.
ASME Code Case 2211 3.
Commitments Contained in this Submittal l
cc:
NRC Region III Office NRC Resident h1spector - PGDP NRC Resident Inspector - PORTS i
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i Mr. Robert C. Pierson August 14,1998 GDP 98-0178, Page 3 References 1.
Letter from Robert C. Pierson (NRC) to Steven A. Toelle (USEC), Paducah Gaseous Diffusion Plant and Portsmouth Gaseous Diffusion Plant, Compliance Plan Issue 3, Action 9, ASME Code Interpretation and Assessment Results (TAC No. L32012), dated June 10, 1998.
2.
Letter from Steven A. Toelle (USEC) to Robert C. Pierson (NRC), Paducah Gaseous Diffusion Plant /Portsmouth Gaseous Diffusion Plant, Docket No. 70-7001 and 70-7002, Compliance Plan Issue 3, Action 9, ASME Code Interpretation and Assessment Results, (TAC No., L32012), USEC Letter GDP 98-0017, dated February 9,1998.
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1 GDP 98-0178 Page1of5 Response to Request for Additional Information (TAC No. L32012)
Compliance Plan Issue 3, Action 9, ASME Code Interpretation and~ Assessment Results In response to the NRC's letter dated June 10,1998 (Reference 1), in which it was noted that 1) the NRC staffis not in position to establish an ASME Code interpretation that positive control of an j
external heating source would obviate the need for a protective device and that 2) the staff l
recommends that USEC either ccmply with the Code, pursue an ASME Code interpretation or seek relief from the protective device provision from NRC, USEC has prepared the following response.
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Further research into the Pressure Vessel Code revealed that,in fact, the ASME Code Committee l
had previously issued Code Case Number 2211 in reply to an inquiry that applies to Compliance l
Plan Issue 3, Action 9. ASME Code Case Number 2211, Pressure Vessels With Overpressure Protection by System Design, Approved August 12,1996 (Enclosure 2), provides a response to the i
following inquiry: "Under what conditions may a pressure vessel be provided with overpressure protection by system design in lieu of a pressure reliefdevice as required by Section VIII, Division 1, para. UG-125(a) and by Section VIII, Division 2, para. AR-1007' In this Code Case, the ASME Code Committee indicated that a pressure vessel may be provided with overpressure protection by system design in lieu of a pressure relief device as required by ASME Section VIII, Division 1, paragraph UG-125(a) provided that certain conditions are satisfied. These conditions, and the extent to which USEC satisfies these conditions at PORTS, are as follows:
Condition (a)
"The vessel is not exclusively in air, water or steam service."
i USEC Status:
The UF cylinders are not exclusively in air, water or steam service.
Condition (b)
"The decision to provide a vessel with overpressure protection by system design is the responsibility of the User. The User shall specify overpressure protection by system design and reference this Code Case in Writing in the purchase documents (per Section VIII, Division 1, para. U-2) for a Division 1 vessel,... The Manufacturer is responsible only for verifying that the User has specified overpressure protection by system design, and for listing this Code Case on the Data Report."
USEC Status:
Ilistorically, the Users (both DOE and USEC) have specified overpressure protection by system l
design; UF cylinders have been and are currently procured without pressure relief devices in 6
l accordance with ANSI N14.1. Ilowever, previous and current procurement documentation does not i
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GDP 98-0178 l
Page 2 of 5 l
l reference this Code Case number. The procurement documentation will be revised to reference the code case for future purchases at PORTS.
1 Condition (c):
"The User shall ensure that the MAWP (see Section VIII, Division 1, para. UG-98) of a vessel is greater than the highest pressure which can reasonably be expected to be achieved by the system.
The User shall conduct a detailed analysis which examines all credible scenarios which could result in an overpressure condition. The "Causes of Overpressure" described in Section 2 of API Recommended Practice 521 " Guide for Pressure-Relieving and Depressuring Systems" shall be considered. An organized, systematic approach, using a multidisciplinary team, such as a Hazards and Operability Analysis (HazOp), Failure Modes, Effects, and Criticality Analysis (FMECA), Fault Tree Analysis, Event Tree Analysis,"What-If" Analysis, or other similar methodology shall be used.
In all cases, the User shall determine the potential for overpressure due to all credible operating and upset conditions, including equipment and instrumentation malfunctions.
- USEC Status:
Detailed analyses have been performed which examine all credible scenarios that could result in an overpressure condition. The plant SAR and TSRs, which comprise Volumes 1,2 and 4 of the Application, and the SARUP. CAR, submitted in accordance with Compliance Plan, Issue 2 and their supporting documentation, provide detailed analyses of the scenarios that could result in an overpressure condition of the UF cylinders. In many cases, the process parameter directly controlled is temperature and/or steam pressure which assures protection against an overpressure condition; administrative controls include those verifying cylinder fill weights. These controls provide overpressure protection for a cylinder being heated in an autoclave.
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The SAR scenarios are discussed in PORTS SAR Section 4.2.3 with additional explanation of controls provided to prevent cylinder overpressure in PORTS SAR Section 3.2.1, which describes autoclave design and operation. The TSRs describe the use ofengineered systems and administrative controls (and their Bases) utilized to maintain cylinder pressures below the MAWP during heating evolutions. SAR Section 3.8 lists the Q systems that provide such overpressure protection to the UF6 l cylinder while being heated in the autoclaves. These engineered controls which limit the UF6 cylinder pressure during heating were described in our previous submittal (GDP 98-0017) of February 9,1998.
The PORTS SARUP discussion of potential high cylinder pressure scenarios is found in Sections 4.3.2.2.2,4.3.2.2.6,4.3.2.2.7,4.3.2.2.14. These scenarios are the result of an organized, systematic approach using multidiscipline teams to identify various accidents and initiating events; this methodology is described in SARUP Sections 4.2 and 4.3 (the methodology application and i
associated calculations are provided in SARUP support documentation which is available at the sites for review). These analyses demonstrate that the existing configuration provides an acceptable level Lo
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l GDP 98-0178 Page 3 of 5 of safety. The basic controls preventing overpressurization of a UF cylinder while heating remain 6
. as described in our previous submittal (GDP 98-0017).
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We believe that the SAR and SARUP satisfy Condition (c) of the Code Case 2211 for the "dctailed
' analysis which examines all credible scenarios which could result in an overpressure condition".
Condition (d):
"The analysis described in (c) shall be conducted by an engineer (s) experienced in the applicable analysis methodology. Any overpressure concerns which are identified shall be evaluated by an engineer (s) experienced in pressure vessel design and analysis. The results of the analysis shall be documented, and signed by the individual in charge of the operation of the vessel. This documentation shall include as a micimum:
l (1) Detailed Process and Instrument Flow Diagrams (P& ids), showing all pertinent elements of the system associated with the vessel.
(2)A description of all credible operating and upset scenarios, including scenarios which l
result from equipment and instrumentation malfunctions.
(3)An analysis showing the maximum pressure which can result from each of the scenarios examined in (2) above.
(4)A detailed description of any instrumentation and control system which is used to limit the system pressure, including the identification of all truly independent redundancies and a reliability evaluation (qualitative or quantitative) of the overall safety system.
The documentation shall be made available to the regulatory and enforcement authorities having jurisdiction at the site where the vessel will be installed. The User of this Code Case is cautioned that prior Jurisdictional acceptance may be required.
USEC Status:
The SAR/SARUP and their' support documentation satisfy Condition (d) of Code Case 2211. The SAR and SARUP analyses were performed by engineers and other technical specialists experienced in accident analysis methodology and overpressure concerns and were reviewed by engineers and other technical specialists experienced in pressure vessel design and analysis. The results of the analyses are documented in the SAR/SARUP and their supporting documents as previously discussed. The system design and controls required, based on the analysis, are in place to prevent overpressure conditions. This documentation has been made available, as part of the Certification Application, to the regulatory authorities having jurisdiction at the site where the vessels are l
installed.
r Item (d)(1): PORTS maintains detailed process and instrument diagrams for the systems providing overpressure protection which show all pertinent elements of the system design which provides overpressure protection.
GDP 98-0178 Page 4 of 5 Item (d)(2): The SAR/SARUP documentation include a description of credible operating and upset scenarios, including scenarios which result from equipment and instrumentation malfunction. These are primarily malfunction of steam control valves and/or safety I
significant (Q or AQ) SSCs as well as failure to implement administrative controls.
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l Item (d)(3): The maximum cylinder pressures and/or temperatures that could develop as a result of the scenarios are discussed either in the SAR/SARUP or in the supporting documents as previously discussed.
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. Item (d)(4): A detailed description of any instrumentation and control system which is used
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to limit the system pressure is provided in SAR Chapter 3 (particularly Section 3.8) and in the Boundary Definition manuals for the credited systems. The discussion regarding reliability and redundancies is contained in the SARUP Section 3.8 and in supporting documents (e.g. PSOAS and DACs for the SARUP).
Condition (e):
"This Case number shall be shown on the Manufacturer's Data Report for pressure vessels that will
. be provided with overpressure protection by system design, and it shall be noted on the Data Report that prior Jurisdictional acceptance may be required."
USEC Status:
The Manufacturer's Data Report does not currently show this Code Case number. This needs to be provided both in procurement documentation (as noted earlier) and in the Manufacturer's Data Report. The reason that this information is not currently provided in the procurement documentation associated with the purchase of cylinders is that the procurement documentation referenced ORO-651 or USEC-651 and/or ANSI N14.1 Standards which do not require this information directly.
ORO/USEC-651, Section 8, describes the use of system design and administrative controls for overpressure protection during heating of UF. cylinders.
Summary The current SAR and the SARUP (currently under NRC review) provide the analyses required to support UF cylinder overpressure protection by system design in lieu of a pressure relief device described in Code Case 2211.- As such, we believe that PORTS is in substantive compliance with the ASME Code with respect to overpressure protection during heating of UF cylinders as described in Code Case 2211. This Code Case discussed the Code requirements for a situation where the protection against overpressurization of the Code vessel is accomplished by system design in lieu
- of pressure relief devices. The " code" requirements for this situation are clearly defined in conditions specified in Case 2211.
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GDP 98-0178 Page 5 of 5 For the heating of UF. cylinders in autoclaves, the plant design and operation (as described in the SAR/SARUP) meet these conditions with one exception (i.e. inclusion of this Case number in procurement documents and having this case number referenced in the Manufacturer Data Report).
As noted above, the Manufacturer's Data Report does not currently show this Code Case number.
USEC commits to meet this Code Case requirement both in procurement documentation and to require this in the Manufacturer Data Report for future cylinder procurement at PORTS.
The reason that this information is not currently contained in procurement documents or Manufacturer Data Reports is that the procurement of cylinders was done referencing the ANSI N14.1 Standard which does not require this information directly. Adequate safety is provided since the ANSI Standard required use of ASME Code requirements in the design, manufacture and inspection of cylinders and specified requirements for pressure test margins, operational fill limits and temperature limits, in service inspections, cleaning and decertifying that are in addition to ASME Code requirements. Additionally, PORTS heats cylinders within autoclaves designed to contain the majority of a release if a loss of cylinder integrity were to occur during heating. This overall approach to safety is and has been used for many years to assure adequate safety rather than reliance on the pressure vessel Code alone.
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GDP 98-0178 Three Pages ASME Code Case 2211 l
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Reproduced from Information Handling Swvicoes The 1995 Boiler and Pressure Vessel Codec 1995 by ASME Tue Aug 04 08:00:081998 2211 2211 Pressure Vessels with Overpressure Protection by System Desip Section VM, Divi 2211 2211 Pressure Vessels with Overpressure Protection by System Desisa Section vm Divi
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SUPP. 6 l
ApprovalDase: 8-12 96 l.
Expiration Date: 8-12-99 SUPP. 6 Ingary:
SUPP. 6 Under what conditions may a pressure vessefb@vided wi^ overpressure protection by system design in Heu of pressure relief device as required by Section VM, Division 1, pars. UG 125(a) and by Section Vm, Division 2, para.
AL100?SUPP.6 Reply:
L SUPP. 6 l
It is the opinion of the Committes that a presswe venel may be provided with overpressure protection by systec:
design in usu of a pressure salief device as required by Section VIII, Division 1, para. UG 125(a) and by Section VM, Division 2, para. AL100 under the following conditions:
(4)The vesselis not exclusively in air, water, or steam service.
@) The decision to provide a vessel with overpressure protection by system design is the responsibilhy of the User.
The User shall specify overpressure protectumby system design and reference this Code Case in writin5 n the purchase i
. documents (per Section VM, Dbision 1, para. U 2) for a Division 1 vessel, or in the User's Design SpeciEcation (per Section vm, Division 2, para. AG-301) for a Division 2 vessel The Manufactaw is responsible only for verifying char 1
the User has speci6ed ov p..
-. protection by system design, and forlisting this Code Case on the Data Report.
(c) The User shall ensure that the MAWP (see Salc' don VM, Division 1, part, UG-98) of the vessel is gr:ater than the 9
highest pressure which can reusumably be expc:ted to be achieved by the systaan. The User shall conduct a dstaded smalysis which examines au credible scenarios which could result in an overpressure condition. 'Ihc "Causes of Overpressure described in Section 2 ofAPI Recommended Practice 521 " Guide for Pressure.Ralieving and Depressurmg Systems" shnu be considered. An organiad, systematic approach, using a multidisciphnary team, such as a Hazards and Operabdity Analysis (Hsz0p), FsRure Modes, Effects, and Crtticahty Analysis (FMECA), Fauh Tree Analysis, Event Tree Analysis, "What-It' Analysis, or other senilar methodology shat! be used. In all cases, the User shall detemuna the potential for overpressure due to all credible operanng and upset conditions, including equipment and instrumentation =h=
($ The analysis described in (c) shall be coeducted by su engineer (s) experienced in the appEcable analysis I
methodology. Any oystpressure concems whiclYitii identined than be evaluated by an engineer (s) experimeed in 1
pressure vessel design and analysis. The results of(he analysis shall be documented, and signed by the individual 2n charge of the operation of the vessel This documentation sha11 include as a mimmne:
(1) Detailed Process and Instrument Plow Digams (P& ids), showing all pertinent elements of the system l
associatedwith the vessel.
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(2) A description of all credible operating ahti upset scenarios, including scenarios which result from equipment and instrumentation malfunctions.
(3) An analysis showing the maximum pressure which can result from each of the se'enarios exa:nined in (2) l
- above, l
(4) A detailed description of any instrumentation and control system which is used to limit fie sys*e= pressure, including the identification of all truly independent r 4=dawies and a reliability evaluation (qualitative or quantitative) of the over:11 safety system.
The documentation shall be made available to the regulatory and enforcement anhorities having jurisdic: ion at the k
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Reproduced frorn Information Handling services 6 The 1995 Boiler and Preeeure Vessel Codec 1995 by ASME Tue Aug.0408:00:081998 2211 2211 Pressure Vessels with Overpressure Protection by System Design Section VIII, Divi I
site where the vessel will be installed. The User of this Code Case is cautier.ed that prior Jurisdictional acceptance may
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be required.
j (e)This Case number shallbe shown on the Wmfetum's Data Report forpressure vessels that will be provuied
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with overpressure protection by system design, sad it shad be noted on the Data Report that prior Jurisdicuocal l
acceptance may be required.SUPP. 6 j
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GDP 98-0178 l
Page1of1 l
l Commitments Contained in this Submittal
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The Manufacturer's Data Report does not currently reference Code Case 2211. USEC commits to revise procurement documentation to reference Code Case 2211 and to require that this Code Case be specified in the Manufacturer Data Report for future UF cylinder 6
l-procurement at PORTS.
2.-
A PGDP specific response to the NRC's letter from Robert C. Pierson (NRC) to Steven A.
l Toelle (USEC), Paducah Gaseous Diffusion Plant and Portsmouth Gaseous Diffusion Plant, l
Compliance Plan Issue 3, Action 9, ASME Code Interpretation and Assessment Results I
(TAC No. L32012), dated June 10,1998 will be provided by August 21,1998.
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