ML20138B784
| ML20138B784 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant, Paducah Gaseous Diffusion Plant |
| Issue date: | 04/23/1997 |
| From: | John Miller 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-97-0062, GDP-97-62, TAC-L32028, NUDOCS 9704290272 | |
| Download: ML20138B784 (24) | |
Text
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70- 700 I AD.lo2V United Statis Enrichmint Corporttion 2 Democracy Center 6903 Rockledge Dnve Bethesda, MD 20817 Tel: (301)564 3200 Fax: (301) 564-3201 li ited States n
Enrichment Corporation JAMES H. MILLER Dir: (301) 564-3309 i
VICE PRESIDENT, PRODUCTION Fax:(301)
)
571-8279 April 23,1997 Dr. Carl J. Paperiello SERIAL: GDP 97-0062 Director, Oflice of Nuclear Material j
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 - Buildings C-331 and C-335 Seismic Upgrades i
Dear Dr. Paperiello:
In accordance with 10 CFR 76.45, the United States Enrichment Corporation (USEC) hereby submits a request for amendment to the certificate of compliance for the Paducah, Kentucky Gaseous Diffusion Plant (GDP). This request is related to the planned modifications to upgrade the seismic capability of Buildings C-331 and C-335 as described in Issue 36 of DOE /ORO-2026, Plan for Achieving Compliance with NRC Regulations at the Paducah Gaseous Diffusion Plant (Compliance Plan). In particular, USEC requests NRC review of the following issues:
As a result of the 10 CFR 76.68(a) review of the proposed modifications to Buildings C-331 and C-335, three issues have been identified as unreviewed safety questions (USQs) requiring prior NRC review and approval: (1) the increased stiffness of the buildings following j
completion of the modifications may increase the number and the probability of seismically-induced equipment failures inside the buildir.gs; (2) the process of installing the new structural steel may temporarily make the building and contained equipment more susceptible to seismically-induced failure as the existing structural frames are altered and/or replaced; and (3) the process ofinstalling the new structural steel may temporarily increase the probability of equipment failures due to postulated load handling accidents during construction. These g~
4 issues are described in more detail in Enclosure 1.
j lll lij lIll, hl}klli til 14 l l ff j
l1 l ljl Il 9704290272 970423 111 ll, l
fl PDR ADOCK 07007001 C
PDR _
Offices in Paducah, Kentucky Portstr outh. Ohio Washington, DC
.-_ - -.. _ - - -. - - - -. - -... ~
Dr. Carl J. Paperiello April 23,1997 GDP 97-0062 Page 2 l
Compliance Plan Issue 36 specifies a December 31, 1997 completion date for these
=
modifications (pending DOE approval of USEC request with justification for a delay). As discussed in Enclosure 1, because of the need to obtain prior NRC review and approval of the identified USQs, the planned modifications cannot be completed by December 31,1997.
Proposed changes to the Justification for Continued Operation (JCO) and the Plan of Action and Schedule for Compliance Plan Issue 36 are provided in Enclosure 2 for NRC review.
The JCO for Compliance Plan Issue 36 discusses emergency response to a postulated seismic event, including sheltering or evacuation of the general public. However, current USEC emergency response guidelines recommend sheltering only in response to UF releases. A 6
proposed change to the JCO for Compliance Plan Issue 36 is also provided in Enclosure 2 for NRC review.
USEC is committed to completing the seismic upgrades to Buildings C-331 and C-335 on the soonest possible schedule to resolve the safety issues identified in Compliance Plan Issue 36. Consequently, USEC requests that this certificate amendment request receive a high priority and that NRC review and approval of this certificate amendment request occur as soon as possible. The results of the analysis of the post-modification building stiffness (performed as a result of the USQ described above) will be submitted to NRC when completed to allow NRC to complete this review and approval process. The amendment should become effective no later than 15 days from issuance.
A copy of this letter.is being provided to DOE to request their approval of the change in the Compliance Plan completion date for the planned modifications.
Any questions related to this subject should be di. c ted to Mr. Steve Routh at (301) 564-3251. New commitments made in this submittal are identified in Enclosure 4.
Sincerely, p
James H. Miller.
[Vice President, Production J
1 Dr. Carl J. Paperiello April 23,1997 GDP 97-0062 Page 3
Enclosures:
1.
United States Enrichment Corporation (USEC), Proposed Certificate Amendment Request, Buildings C-331 and C-335 Seismic Upgrades, Detailed Description of Change 2.
NRC Certificate Amendment Request, Paducah Gaseous Diffusion Plant, Letter GDP 97-0062, Removal / Insertion Instructions & Pages 3/4,4/5 of Compliance Plan Issue 36 3.
United States Enrichment Corporation (USEC), Proposed Certificate Amendment Request, Buildings C-331 and C-335 Seismic Upgrades, Significance Determination 4.
Commitments Contained in this Submittal l
cc:
NRC Region III Oflice, w/ enclosures NRC Resident Inspector - PORTS, w/o i
NRC Resident Inspector - PGDP, w/ enclosures Mr. Joe W. Parks (DOE), w/ enclosures i
Mr. Randall M. DeVault, w/ enclosures i
OATH AND AFFIRMATION i
I, James H. Miller, swear and affirm that I am Vice President, Production, of the United States Enrichment Corporation (USEC), that I am authorized by USEC to sign and file with the Nuclear i
Regulatory Commission this Certificate Amendment Request for the Paducah Gaseous Diffusion Plant, that I am familiar with the contents thereof, and that the statements made and matters set forth therein are true and correct to the best of my knowledge, information, and bel'cf.
i
~'
7
/
James H. Miller Subscribed to before me on this e23 day of b4[b
,1997.
t Ybbt duk 6W Notary Public BERNICE R. LAWSON NOTARY PUBUC STATE OF MARYLAND Cerr.ficata f, tad in Montgomery Couny Commission Expires Auge:t 1,1997 l
l
i
. to GDP 97-0062 Page1of7 United States Enrichment Corporation (USEC)
Certificate Amendment Request Buildings C-331 and C-335 Seismic Upgrades Detailed Description of Change 1
1.0 Purpose The purpose of this certificate amendment is to request NRC review and approval of the following issues related to Issue 36 " Seismic Capability of Buildings C 331 and C 335 " of DOE /ORO 2026 Pl an for Achieving Compliance with NRC Regulations at the Paducah Gaseous Diffusion Plant (Compliance Plan):
As a result of the 10 CFR 76.68(a) review of the proposed modifications to Buildings C-331 and C-335, three issues have been identified as unreviewed safety questions (USQs) requiring prior NRC review and approval: (1) the increased stiffness of the buildings following completion of the modifications may increase the number and the probability of seismically-indaced equipment failures inside the buildings; (2) the process of installing the new simctural steel may temporarily make the building and contained equipment more susceptible to seismically-induced failure as the existing structural frames are altered and/or replaced; and (3) the process ofinstalling the new structural steel may temporarily increase the probability of equipment failures due to postulated load handling accidents during construction.
Compliance Plan Issue 36 specifies a December 31,1997 completion date for these modifications (pending DOE approval of USEC request with justification for a delay).
Because of the need to obtain prior NRC review and approval of the identified USQs, the planned modifications cannot be completed by December 31,1997.
The justification for continued operation (JCO) for Compliance Plan Issue 36 discusses emergency response to a postulated seismic event, including sheltering or evacuation of the general public. However, current USEC emergency response guidelines recommend sheltering only in response to UF releases.
2.0 Background
Compliance Plan Issue 36 requires USEC to upgrade the structural capacity of Buildings C-331 and C-335 to withstand a 0.15 g magnitude earthquake and presents a justification for continued operation of these buildings during the interim period until the seismic modifications are completed. As required by the JCO, the following compensatory measures are being implemented during this interim period:
1 i
. to GDP 97-0062 Page 2 of 7 Operations in Buildings C-331 and C-335 are limited to subatmospheric pressure within i
the enriclunent cascade equipment.
Operations personnel have been instructed on the specific emergency procedures for shutting down the affected enrichment cascade and building ventilation systems following a seismic event.
4 Building access is limited to only those individuals essential to operations, inspections, or those personnel performing the modifications until they are complete.
4 Compliance Plan Issue 36 concludes that "..the risk to the public and the on-site workers from the unmitigated response of Buildings C-331 and C-335 is not extreme and can be accepted without undue harm with the compensatory measures imposed on operations remaining in effect until the modifications are complete while the structural weaknesses are being corrected."
3.0 Discussion ofIssues 3.1 Unreviewed Safety Questions Associated With Planned Seismic Upgrades to Buildings C-331 and C-335 As a result of the 10 CFR 76.68(a) review of the proposed modifications to Buildings C-331 and C-335, three issues have been identified as unreviewed safety questions (USQs) requiring prior NRC review and approval. These issues are discussed in further detail below.
Issue 1 The increased stiffness of the buildings following completion of the modifications may increase the number and the probability of seismically-induced equipment failures inside j
the buildings.
l The following is a summary of this issue:
Table 4.6-2 of the Safety Analysis Report (SAR) identifies equipment currently predicted to fail as a result of an analyzed 0.18 g magnitude earthquake.
Tables 4-1 and 4-2 of the SAR Upgrade (SARUP) document (Reference 1) identify equipment in Buildings C-331 and C-335 predicted to fail as a result of a revised i
Evaluation Basis Earthquake of 0.15 g once the stmetural modifications are completed.
Some of the failures identified in SARUP Tables 4-1 and 4-2 are different than those identified in SAR Table 4.6-2. SARUP Tables 4-1 and 4-2 are based on the conceptual design of the planned stmetural modifications to Buildings C-331 and C-335.
Equipment failure calculations based on the final design of the structural modifications were initiated on February 19,1997 and are scheduled to be completed and approved by j
1
. to GDP 97-0062 Page 3 of 7 June 27,1997.
The revised calculations may predict additional and/or different seismically-induced equipment failures than those identified based on the conceptual structural design. (Preliminary results predict few, if any, additional equipment failures.)
The fmal results of the revised calculations will be forwarded to NRC.
Based on the above discussion, this issue has been determined to be an unreviewed safety question because the probability of a malfunction of equipment important to safety previously evaluated in the safety analysis report may be increased. The completed structural modifications to Buildings C-331 and C-335 may result in seismically-induced equipment failures different than those currently identified in the SAR.
Although the probability of seismically-induced equipment failures may be increased by the stitTening of Buildings C-331 and C-335, the consequences of these postulated equipment failures are bounded by the seismic failures evaluated in the JCO for Compliance Plan Issue 36. The JCO evaluates four postulated seismic failure cases that predict uranium uptake and HF exposure to individuals (see Table 1 of Compliance Plan Issue 36). The bounding case assumes a complete building collapse and the release of the entire contents of the cascade system. The calculated consequences of this bounding case exceed the estimated consequences of the small number of equipment failures that may be predicted to result from the stiffening of Buildings C-331 and C-335.
Issue 2 The process ofinstalling the new structural steel may temporarily make the building and contained equipment more susceptible to seismically-induced failure as the existing structural frames are altered and/or replaced.
The following is a summary of this issue:
SAR Table 4.6-2 identifies equipment currently predicted to fail as a result of an analyzed 0.18 g magnitude ear 1hquake.
In various locations in Buildings C-331 and C-335, existing structural framing is planned to be removed and replaced with upgraded structural steel. Consistent with standard practice for upgrading structures, temporary supports or shoring will be used as required and the sequence of removal of old components and installation of new components will be selected based on the stability of the in-process structure. These standard practice techniques account for static and construction-activity dynamic loading, but do not necessanly account for postulated seismic loading. Thus, during the short period of time that a particular location of the building is being modified (on the order of 2 to 3 days for each location), if a seismic event were to occur, there may be an increased probability of localized building and/or equipment failures over those currently evaluated in the SAR.
As the project progresses, various portions of the overall structure may be in a weakened condition (as discussed above) while other portions may be unaltered or have their
3 e to GDP 97-0062 Page 4 of 7 alterations completed.
It is nearly impossible to analyze the various possible combinations of these configurations.
However, because of the variations in seismic / structural response throughout the buildings, there may be an increased probability of building and/or equipment failures should a seismic event occur.
Based on the above discussion, this issue has been determined to be an unreviewed safety question because the probability of a malfunction of equipment important to safety previously evaluated
. in the safety analysis report may be increased. The process of modifying Buildings C-331 and C-335 may temporarily make the buildings and contained equipment more likely to fait during a postulated seismic event.
Although the probability of seismically-induced building and equipment failures may be temporarily increased during the construction process, the consequences of these postulated failures are bounded by the seismic failures evaluated in the JCO for Compliance Plan Issue 36. The JCO evaluates four postulated seismic failure cases that predict uranium uptake and HF exposure to individuals (see Table 1 ofCompliance Plan Issue 36). The bounding case assumes a complete building collapse and the release of the entire contents of the cascade system. The calculated consequences of this bounding case exceed the estimated consequences of any building or equipment failures that may be predicted to result
- should a seismic event occur during construction activities. In addition, the current restrictions on subatmospheric operation in Buildings C-331 and C-335 serve to further reduce any postulated releases i
during the construction period below those evaluated in Compliance Plan Issue 36.
Issue 3-The process ofinstalling the new structural steel may temporarily increase the probability of equipment failures due to postulated load handling accidents during construction.
The following is a summary of this issue:
A crane failure accident analysis for the cascade buildir.gs i.e presented 'm SAR Section 4.3.2.1.1. This analysis assumes that approximately 20J moves of major equipment are required each year and approximately 2% of the move time is over operating equipment.
The analysis assumes the drop of a "000" compressor (which weighs approximately 33 tons including lining fixtures) onto cascade equipment that is running above atmospheric pressure.
The project plan for installation of the seismic upgrades in Buildings C-331 and C-335 identifies the need for approximately 2300 liRs of structural steel shapes and related materials in each building. Some of the liRs will be over, or in proximity to, operating Q or AQ equipment, including the cascade. The lins will be hand-rigged (i.e., no crane j
will be used) and involve structural steel shapes with a length between 20 and 50 feet, weighing less than 5 tons.
I l
Enclosure I to
)
GDP 97-0062 J
Page 5 of 7 The following controls will be applied to each lin associated with the seismic modifications:
Lin time will be minimized to reduce exposure to drop hazards.
Subatmospheric pressures will be maintained within the cascade process equipment.
Lift plans will be prepared and approved in accordance with plant procedures.
Each lin plan will include step-by-step instructions along with appropriate witness and/or inspection hold points.
The lift will be planned from initial rigging, to liR placement, stabilization, and rigging removal. Planning for each lin will include an identification of actions that would be taken in response to a hypothetical load handling accident.
A constmetion engineer will be assigned to provide dedicated oversight.
In addition to the controls for each lin described above, the following supplemental controls will be applied for each lift that is over, or in proximity to, operating Q or AQ j
equipment:
Facility owners will be notified prior to the lin.
An Operations representative will witness the lin and will maintain voice contact with the facility Area Control Room (ACR) throughout the lin to ensure that the ACR is notified as quickly as possible should a load handling accident occur.
Based on the above discussion, this issue has been determined to be an unreviewed safety question because the probability of a malfunction of equipment important to safety previously evaluated in the safety analysis report may be increased. The number oflins during the planned construction activities exceeds the number oflias currently evaluated in the SAR; thus, a load handling accident impacting equipment important to safety may be more likely to occur during the construction period.
Although the probability of equipment failure as a result of a postulated load handling accident may be temporarily increased during the construction process, the consequences of these postulated failures are bounded by failures evaluated in the SAR and the JCO for Compliance Plan Issue 36. First, because the weight of each lin is significantly less than evaluated in S AR Section 4.3.2.1.1 (5 tons versus 33 tons), a postulated load handling accident would produce less damage to cascade equipment (e.g., size of hole, single versus multiple holes, etc.) than assumed by the accident analysis. Second, the JCO for Compliance Plan Issue 36 evaluates four postulated seismic failure cases that predict uranium uptake and HF exposure to individuals (see Table 1 of Compliance Plan Issue 36). The bounding case assumes a complete building collapse and the release of the entire contents of the cascade system. The calculated consequences of this bounding case exceed the estimated consequences of any equipment failures that may be predicted to result due to a postulated load handling accident. In addition, the current restrictions on subatmospheric operation in Buildings C-331 and C-335 serve to further reduce any postulated releases during the construction period below those evaluated in Compliance Plan Issue 36.
j Enclosure I to GDP 97-0062 Page 6 of 7 3.2 Change in Completion Date for Seismic Modifications to Buildings C-331 and C-335 The Plan of Action and Schedule for Compliance Plan Issue 36 requires that:
Modifications to increase the seismic capability for floor and roof sections in Buildings C-331 and C-335 will be completed by December 31,1997 (pending DOE approval of USEC request with justification for a delay from July 31,1997 - current commitment date to DOE).
In order to complete the modifications by December 31,1997, the installation of structural steel needed to begin on March 18,1997. However, structural steel installation has not yet started because the 10 CFR 76.68(a) evaluation of the proposed modifications identified three issues as involving unreviewed safety questions (see Section 3.1). To account for the need to obtain prior NRC review and approval of the identified USQs, USEC requests that the completion date for the seismic modifications to Buildings C-331 and C-335 be changed to 15 months following NRC approval of this certificate amendment request. A proposed change to the Plan of Action and Schedule for Compliance Plan Issue 36 is provided in Enclosure 2. The 15-month duration is shown in Attachment I and includes final design approval, construction restart, steelinstallation, and final project closecut. Attachment 2 provides a summary schedule of completed and ongoing activities that do not require prior NRC review and approval of this certificate amendment request. Ongoing activities include the procurement and fabrication of the stmetural steel and interference relocations. (Detailed project schedule information is available at the site.)
A review of the JCO for Compliance Plan Issue 36 has been performed to determine if any changes are required as a result of extending the completion date for the seismic modifications. The conclusions of this review are that, if the compensatory measures identified in the current JCO remain in effect, continued operation of Buildings C-331 and C-335 isjustified during the extended period.
3.3 Change in Emergency Response to a Postulated Seismic Event The JCO for Compliance Plan Issue 36 describes risks to the general public of a postulated seismic event and identifies emergency response actions to be taken:
The risk of exposure to the general public of moderate (uptake of 100-150 mg of uranium) and low (50-100 mg uptake) renal injuries was estimated to be 0.15 injuries and 0.78 injuries / year, respectively, assuming no benefit from an emergency response.
If emergency response is considered and credited with a factor of 2 benefit due to either sheltering or evacuation, then the risk is essentially zero, at 0.15 low level renal injuries / year.
1
. to GDP 97-0062 Page 7 of 7 This wording indicates that, for the general public, the emergency response that is credited for safety can be either sheltering or evacuation. However, Section 5.4.2 of the Emergency Plan (EP) states that the recommended response to emergencies such as releases for the general public outside the site f
boundary is to seek shelter only (and not evacuation). EP Section 5.4.2 further states that protective actions beyond sheltering would be directed by off-site authorities who are responsible for the members of the public in theirjurisdiction. Although these other protective actions may include evacuation, such an evacuation should not be credited for safety in the JCO because this is an action controlled by off-site authorities and not by plant personnel. The emergency response that should be credited for safety is sheltering. A proposed change to the JCO for Compliance Plan Issue 36 has been included in Enclosure 2 to eliminate evacuation as an alternative to be credited for protection of the general public. This change will make the Compliance Plan JCO consistent with the emergency response actions described in the Emergency Plan. The change does not, however, prevent off site authorities from ordering an evacuation i
of the public.
References 1.
KY/EM-174, Safety Analysis Report, Volume 2, Paducah Gaseous Diffusion Plant, Paducah, Kentucky; Prepared by Lockheed Martin Energy Systems, Inc. for the U.S. Department of Energy; Transmitted by February 14,1997 Letter from Joe W. Parks (DOE) to Mr. George P. Rifakes, USEC.
Attachments 1.
PGDP Seismic Upgrade - Buildings C-331 & C-335, Tasks Dependent on NRC Approval of Certificate Amendment Request,4/23/97.
^
2.
PGDP Seismic Upgrade - Buildings C-331 & C-335, Tasks That Do Not Require NRC Approval of Certificate Amendment Request,4/23/97.
l
PGDP Seismic Upgrade - Buildings C-331 & C-335 Letter GDP 97C62 Endosure 1 Tasks Dependent on NRC Approval of Attadment 1 Certificate Amendment Request ID Task Name Duration 1 l 2 l 3 l 4 l 5 l 6 l 7 l 8 l 9 l 10 l 11 l 12 l 1 l 2 l 3 1
NRC Approve Amendment Request Od p 2
3 Complete Modification Package 10d 4
5 PORC Review Od 6
7 Certify for Construction / Construction Start 15d 8
l' 9
Field installaten - Cell Floor 261d 10 11 Field installation - Ground Floor 236d 12 13 Project Closeout 20d I
Task Summary Rolled Up Progress Progress
- Rolled Up Task Date Milestone Rolled Up Milestone Q Page 1 i
PGDP Seismic Upgrade - Buildings C-331 & C-335 Letter GDP 97-0C32 Tasks That Do Not Require NRC Approval of Attaenwnt 2 Certificate Amendment Request 1996 1997 l
ID Task Name Duration Start Finish JlFlMlAlMlJlJlAlSlOlNlD JlFlMlAlMlJlJlAlSlQlN l
f 1
DESIGN 369d tl30/96 6/27/97 2
Conceptual Desgn 57d 1/30/96 4/17/96 1
3 Final Design 204d 4/18/96 1/28/97 4
PORC Review 33d 1/29/97 3/14/97 5
Prepare Amendment Request 25d 3/17/97 4/18/97 6
Revise Equipment Failure Calculations 93d 2/19/97 6/27/97 7
8 CONSTRUCTION 397d 3/1/96 9/8/97 I
9 Bid Sol:cstation 108d 3/1/96 7/30/96
. ]
SO Award 79d 7/31/96 11/18/96 11 Site Mobilizaten 105d 12/2/96 4/25/97 92 Procure Cell Floor Steet 39d 12/30/96 2/20/97 t
13 Procure Ground Floor Steel 57d 4/10/97 6/27/97 14 Fabncate Cell Floor Steel 46d 4/14/97 6/16/97 95 Fabncate Ground Floor Steet 51d 6/30/97 9/8/97 16 t
97 INTERFERENCE RELOCATIONS 271d 11/8/96 11/21/97 98 Mobilization 166d 11/8/96 6/27/97 r
j 19 Cell Floor Relocations 96d 2/17/97 6/30/97 j
20 Ground Floor Relocations 125d 6/2/97 11/21/97 i
Task Summary Rolled Up Progress Seismic Upgrade C-331 & C-335 Progress Rolled Up Task Date:4/23/97 Milestone Rolled Up Mdestone O l
Page 1 I
. to GDP 97-0062 5 Pages Total NRC Certificate Amendment Request Paducah Gaseous Diffusion Plant Letter GDP 97-0062 Removal / Insertion Instructions Remove Pages Insert Pages PLAN FOR ACIIIEVING COMPLIANCE WITII NRC REGULATION AT TIIE PADUCAll GASEOUS DIFFUSION PLANT (DOE /ORO-2026)
Issue 36, Seismic Capability of Buildings Issue 36, Seismic Capability of Buildings C-331 and C-335 C-331 and C-335 Pages 3/4, 5/6 Pages 3/4,5/6
. Seistnic Capability of Buildings C-331 and C-335 PROPOSED Issue 36, Page 3 RAC 97C089 reduce displacements thus ensuring the overall building integrity.
Completion of the l
modifications will bring the PGDP process building structures into compliance within the interpretation of the 1985 SAR and current seismic requirements for GDP hazardous facilities.
However, the upgraded SAR seismic equipment analysis is not yet complete. Additional modifications to equipment could be recommended depending on the findings of the remaining equipment evaluations and the analyses of the HF and UO F2 Projected releases.
2 PGDP plans to continue operation with two process buildings, C-331 and C-335, in a seismically weak condition until the completion of building reinforcement modifications.
Continued operation of the processes in these buildings is justified in the interim since the increased risk to the general public and on-site workers is within an acceptable level. The risk increase to the public is a small increase in the chance of an exposure to UO F and HF causing 2 2 minor to moderate renal injuries. The risk increase to some on-site workers is a moderate (factor of 2 to 3) increase in the chance of both exposure to toxic releases and physical injury. (See the
)
"Paducah Gaseous Diffusion Plant Justification for Continued Operation: Temporary Operation of Buildings C-331 and C-335 with Potentially Severe Structural Damage Due to Evaluation Basis Earthquake Loads," prepared by the Department of Energy Regulatory Oversight, Oak Ridge.
TN, dated May 17, 1996.) Compensatory measures were initiated upon recognition of the structural deficiency and will remain in place until the corrective modifications are complete.
These measures minimize the number of shift personnel in the affected buildings during the interim period, and the allowed power level in the two buildings is limited to maintain the cascade subatmospheric thereby minimizing the release after a seismic event.
The conclusion that the risk level is acceptable during the interim operating period is supported by evaluations of the consequences to the public and on-site workers from conservative release scenmos based on the projected and bounding building failures that are possible up to the evaluation basis earthquake. Physical effects such as the impact of a seismically induced fire also were examined as part of these scenarios.
i The projected structural response of the two buildings up to an Evaluation Basis Earthquake (250-year return interval, peak ground acceleration equivalent: 0.15 g) is the inward collapse of three areas of each building's roof, mezzanines, and cell floor. These areas are about 20 feet wide and run the length of each building in the direction of the structural expansion joint between internal structural units. The collapse could cause the release of UF., UO F, and HF. In 2 2 addition, there is some probability that the buildings could collapse in response to the loading of earthquakes that produce accelerations approaching 0.15g. Based on the possible structural response, four exposure cases were evaluated. A bounding case (Case 1) assumed that the j
building collapsed (i.e., the building fell over onto its side) and the entire contents of the cascade system was released into the collapsed structures. It should be noted that the load bearing capacity of the converters located throughout the building on the cell floor would prevent the complete flattening of the structure and provide a vertical air space approximately 8 feet high. The analyzed quantity of the UO F and HF released was not reduced by physical considerations such 2 2 as the material that would remain in the cascade piping and equipment or may deposit in the j
building or the vicinity of the building due to aerosol deposition. However, the effects of thermodynamics and the mixing of fluids (water vapor and R-114 Freon) in the building were considered. Case 2 used a conservative, but more realistic, engineering analysis basis that included an esthnate of the UF. that would remain in the converters following the cascade system ruptures. The amount of aerosol deposition that would occur during the residence time of the release cloud in the buildings was also considered. This release case is a conservative but PGDP, April 23,1997 PROPOSED
Issue 36, Page 4 PROPOSED Seismic Capability of Buildings C-331 and C-335
' RAC 97C089 defendable estimate of the bounding physical state of the building. Cases 3 and 4 are similar cases of the buildings' expected actual structural response to an Evaluation Basis Earthquake event (including the failure of areas of the buildings at the structural expansion joints). Case 3 is based 3
on a highly conservative estimate of the cascade damage that would be sustained if the roof, mezzanine, and cell floor failed as predicted and no aerosol deposition occurred. Case 4 is the same as case 3 with consideration given to aerosol deposition.
The results of the four evaluation cases are summarized in the following table:
Table 1. Uranium Uptake and HF exposure
- to Individuals Evaluation Case Meteorology Maximum Maximum IIF Exposure HF Exposure Class-Wind Uranium Inhaled Uranium Inhaled Concentration Concentration speed (m/sec)
Mass (mg) at 1 Mass (mg) at 5 (ppm)-1 mile (ppm)-5 miles mile miles I. Building Collapse-No retention in D-4 139 70 38 19 Cascade (Bounding Case)
II. Building Collapse-Conservative D-4 45 16 15 5
estimate of retention in Cascade III. Partial Building Failure F-3 32 7
17 3
with No Aerosol l
Depcsition IV. Partial Building Failure F-3 20 4
11 2
with Aerosol Deposition
- IIF exposures are based on I hour average concentrations.
The results of all but the bounding case (Case 1) show the potential for only a mild exposure, nearly within the accident evaluation guidelines. The bounding case consequences 1
indicate the potential for significant renal injury, that would not be potentially life threatening at l
one mile distance from the release point. One mile is essentially the distance to the site boundary from the buildings in question. The risk of exposure to the general public of moderate (uptake of 100-150 mg of uranium) and low (50-100 mg uptake) renal injuries was estimated to be 0.15 injuries and 0.78 injuries / year, respectively, assuming no benefit from an emergency response.
If emergency response is considered and credited with a factor of 2 benefit due to sheltering, i
then the risk is essentially zero, at 0.15 low level renal injuries / year. Given the highly conservative nature of the evaluation of the release and the low consequences, continued operation does not pose a significant undue risk to the public during the period of operations until building modifications are completed.
i i
PGDP, April 23, 1997 PROPOSED
m. _ %
Seismic Capability of Buildings C-331 and C-335 PROPOSED Issue 36, Page 5
- RAC 97C089 The risk to workers in the buildings was estimated as well. Based on an assumed 5 percent chance of building collapse and a 50 percent chance of being present in the building (i.e., on shift), the injury rate to individual workers was estimated at approximately 1 x 10-4 per year with a total injury rate risk estimated at 2.6x 10-5 injuries per year (for an operating staff of 26). This is judged to be acceptable and is no greater than the risk of general office work on-site. Injury from structures may even be higher in the office buildings, although the probability of exposure to HF and UO F releases would be greater in the process buildings.
2 2 Therefore, it is concluded that the risk to the public and the on-site workers from the unmitigated response of Buildings C-331 and C-335 is not extreme and can be accepted without undue harm with the compensatory measures imposed on operations remaining in effect until the modifications are complete while the structural weaknesses are being corrected.
PLAN OF ACTION AND SCIIEDULE The actions to upgrade the seismic capabilities of Buildings C-331 and C-335 are as follows:
1.
Based on a Directive for Information provided to USEC by DOE on September 22,1995, the USEC evaluation of the currently available information from the DOE safety analysis upgrade effort related to seismic capabilities at the facility completed on October 23,1995, the DOE evaluation of the USEC response dated October 31, 1995, USEC's proposed resolution documented on January 9,1996, and USEC's certificate amendment request dated April 23,1997, the following actions are being implemented to ensure the protection of the workers and public health and safety:
Until the completion of modifications discussed below, operations in Buildings C-331 and C-335 will be limited to subatmospheric pressure within the enrichment cascade equipment.
Operations personnel will be instructed on the specific emergency procedures for shutting down the affected enrichment cascade equipment and building ventilation systems following a seismic event.
Building access will be limited to only those individuals essential to operations, inspections, or those personnel performing the modifications until they are complete.
Modifications to increase the seismic capability for floor and roof sections in Buildings C-331 and C-335 will be completed within 15 months of NRC approval of USEC's cenificate amendment request dated April 23,1997, (pending DOE approval of USEC request with justification for a delay from July 31,1997 - current commitment date to DOE).
2.
At the time of transition from DOE regulatory oversight to NRC regulatory oversight, USEC will inform NRC of the interim measures still in effect for the affected buildings and equipment and the current status of upgrading the seismic capabilities of the affected buildings and equipment.
PGDP, April 23,1997 PROPOSED
Issue 36, Page 6 PROPOSED Seismic Capability of Buildings C-331 and C-335
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Documentation prepared for the design of the modification and other relevant information l
concerning implementation will be provided to the NRC, upon issue, for information and review.
4.
By December 1,1997, USEC shall submit for NRC approval an updated seismic risk analysis for the Paducah plant site. The analysis shall:
Consider all available regional and site-specific data published by the U.S. Geological Survey.
Provide an estimate of the peak ground acceleration for a seismic event with a 250-year return period. If the estimate is greater than 0.15g, then the return period for a 0.15g event shall also be estimated.
Any proposed modifications that may result from this analysis shall be e,ubject to a backfit analysis pursuant to 10 CFR 76.76(b).
SUMMARY
OF REQUIREMENTS, COMMITMENTS, AND NONCOMPLIANCES Issue: Seismic Capability of Buildings C-331 and C-335 Code of Federal Regulations Part Title 10 76.35(a)(4), 76.35(a)(6), 76.35(a)(8), 76.85 Application Conunitment Section Safety Analysis Report 2.1.1, 2.6, 3.1, 3.3, 3.4, 4.2.2.6, 4.6.1, 4.7, Table 4.9-1 Application Noncompliance Statement Section Safety Analysis Report 2.7, 3.16.1, 4.10 PGDP, April 23, 1997 PROPOSED
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GDP 97-0062 Page1 of5 United States Enrichment Corporation (USEC)
Certificate Amendment Request Buildings C-331 and C-335 Seismic Upgrades 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 Overall Decrease in the EfTectiveness of the Plant's Safety. Safecuards. or Security Programs This certificate amendment requests NRC review of three unreviewed safety questions (USQs) associated with the seismic upgrades to Buildings C-331 and C-335 and an extension to the completion date for these modifications. The seismic /stmetural capacity of Buildings C-331 and C-335 is not addressed in the plant safety, safeguards, or security programs contained in Volume
of the Application for United States Nuclear Regulatory Commission Certification for the Paducah Gaseous Diffusion Plant.
This certificate amendment also requests NRC review and approval of a change to the Justification for Continued Operation (JCO) for Compliance Plan Issue 36, " Seismic Capability of Buildings C-331 and C-335," to remove the reference to evacuation as an alternative to be credited for protecting the safety of the general public in response to a postulated seismic event.
This change will make the Compliance Plan JCO consistent with the recommended response of sheltering only for the general public (and not evacuation) as described in the Emergency Plan.
Also, the change does not prevent off-site authorities from ordering an evacuation of the public as described in the Emergency Plan.
I For these reasons, the effectiveness of the plant's safety, safeguards, and security programs is unafTected by this certificate amendment.
i 2.
No Significant Change to Any Conditions to the Certificate of Comoliance None of the Conditions to the Certificate of Compliance address the specific USQs raised, the schedule for completing the seismic upgrades to Buildings C-331 and C-335, or evacuation as an optional response in an emergency. Thus, the proposed changes have no impact on any of the Conditions to the Certificate of Compliance.
3.
No Significant Change to Any Condition of the Anoroved Comoliance Plan Issue 36 is the only portion of the Compliance Plan affectcJ by the proposed changes. The identified USQs do not have a direct impact on this Compliance Plan issue. In fact, the consequences of the postulated seismic failures evaluated in the JCO for Compliance Plan Issue 36 bound the consequences of the identified USQs. However, the need to obtain NRC review of the USQs will result in a change to the scheduled completion date for the seismic upgrades.
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Extending the completion date for the modifications is not a significant change because the JCO for Compliance Plan issue 36 will remain in efTect until the modifications are completed, including the required compensatory measures.
Removing the reference to evacuation as an alternative for protecting the safety of the general public is not a significant change because sheltering provides equivalent protection. Also, the change does not prevent off-site authorities from ordering an evacuation of the public.
4.
No Siunificant Increase in the Probability of Occurrence or Conseauences of Previousiv Evaluated Accidents a.
Issue I has been identified as a USQ because the increased stiffness of Bu ldings C-331 and C-335 following completion of the seismic modifications may increase the number and the probability of seismically-induced equipment failures inside the buildings.
IIowever, the number and location of equipment failures that are predicted to occur based on the conceptual design of the structural modifications are not significantly different from those currently identified in the SAR. Additionally, the preliminary results of revised calculations based on the final stmetural design predict few, if any, additional failures.
The consequences of seismically-induced equipment failures following completion of the upgrades are bounded by the seismic failures evaluated in the JCO for Compliance Plan Issue 36. Four postulated seismic failure cases are evaluated in the JCO that predict uranium uptake and IIF exposure to individuals (see Table 1 of Compliance Plan Issue 36). The bounding case assumes a complete building collapse and the release of the entire contents of the cascade system. The calculated consequences of this bounding case exceed the estimated consequences of the small number of equipment failures that may be predicted to resul; from the stiffening of Buildings C-331 and C-335.
b.
Issue 2 has been identified as a USQ because the process ofinstalling the new structural steel may make the building and contained equipment more susceptible to seismically-induced failure as the existing structural frames are altered and/or replaced. However, the potential increase in probability of failure is temporary and will only exist during installation of the modifications.
Although the probability of seismically-induced building and equipment failures may be temporarily increased during the construction process, the consequences of these postulated failures are bounded by the seismic failures evaluated in the JCO for Compliance Plan Issue 36. Four postulated seismic failure cases are evaluated in the JCO that predict uranium uptake and 11F exposure to individuals (see Table 1 of Compliance Plan Issue 36). The bounding case assumes a complete building collapse and the release of the entire contents of the cascade system. The calculated consequences of this bounding case exceed the estimated consequences of any building or equipment failures that may be predicted to result should a seismic event occur during constmetion activities.
In addition, the current restrictions on subatmospheric operation in Buildings C-331 and
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Page 3 of 5 j
C-335 serve to further reduce any postulated releases during the construction period below those evaluated in Compliance Plan Issue 36.
c.
Issue 3 has been identified as a USQ because the process ofinstalling the new structural steel may temporarily increase the probability of equipment failures due to postulated load handling accidents during construction.
However, the potential increase in probability of failure is temporary and will only exist during installation of the modifications. Additionally, various controls will be applied to each lin associated with the seismic modifications to preclude the possiblity of an accidental load handling accident.
l Although the probability of equipment failure as a result of a postulated load handling accident may be temporarily increased during the construction process, the consequences of these postulated failures are bounded by failures evaluated in the SAR and the JCO for 4
Compliance Plan Issue 36. First, because the weight of each lin is significantly less than evaluated in SAR Section 4.3.2.1.1 (5 tons versus 33 tons), a postulated load handling accident would produce less damage to cascade equipment (e.g., size of hole, single versus multiple holes, etc.) than assumed by the accident analysis. Second, the JCO for Compliance Plan Issue 36 evaluates four postulated seismic failure cases that predici uranium uptake and HF exposure to individuals (see Table 1 of Compliance Plan Issue 36). The bounding case assumes a complete building collapse and the release of the entire contents ofthe cascade system. The calculated consequences of this bounding case exceed the estimated consequences of any equipment failures that may be predicted to result due to a postulated load handling accident. In addition, the current restrictions on subatmospheric operation in Buildings C-331 and C-335 serve to further reduce any postulated releases during the construction period below those evaluated in Compliance Plan Issue 36.
i d.
Extending the completion date for the seismic upgrades has no effect on the probability of a seismic event. Although Buildings C-331 and C-335 will remain in a weakened condition for a longer time, the consequences of postulated seismic failures of these buildings will be no greater than those previously evaluated in the JCO for Compliance Plan Issue 36. The compensatory measures will also remain in effect until completion of the modifications.
c.
There is no effect on the probability of a seismic event by removing the reference to evacuation as an alternative for protecting the safety of the general public. There is also no change in the consequences of the postulated seismic failures evaluated in the JCO for Compliance Plan Issue 36 because sheltering affords equivalent protection to evacuation.
Also, the change does not prevent off-site authorities from orderity an evacuation of the public.
For these reasons, there will be no significant increase in the probability of occurrence or the consequences of previously evaluated accidents.
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No New or Different Tyne of Accident The accident scenario related to this cenificate amendent is a seismic event that results in a release of UF from Buildings C-331 and C-335. No new or difTerent type of accident has been 6
identified.
6.
No Significant Reduction in Margins of Safety This cenificate amendment request has no impact on the margins of safety as defined in the basis for any Technical Safety Requirement. Therefore, no significant reductions in margins of safety will result.
7.
No Significant Decrease in the Effectiveness of any Program or Plans Contained in the Certificate Application For the reasons discussed in the response to Item 1 above, there will be no significant decrease in the effectiveness of any program or plan contained in Volume 3 of the Certification Application.
8.
The pronosed changes do not result in undue risk to 1) nublic health and safety. 2) common defense and security. and 3) the environment a.
As discussed in the response to Item 4, the three USQs and the extension of the completion date for the seismic upgrades to Buildings C-331 and C-335 will not result in a significant increase in the probability of occurrence of previously evaluated accidents.
Also, there will be no increase in the consequences of previously evaluated accidents and no new accidents have been identified. Thus, there will be no undue risk to public health and safety or to the environment. The USQs have no impact on common defense and security.
b.
Removing the reference to evacuation as an alternative for protecting the safety of the general public will not result in undue risk to public health and safety because sheltering provides equivalent protection and the ability of oft-site authorities to order an evacuation of the public is not changed. Removing the reference to evacuation has no impact on common defense and security or the environment.
9.
No Change in the Tynes or Significant Increase in the Amounts of Anv Efiluents that May be Released Offsite As discussed in the response to Item 4, there will be no increase in the consequences of a postulated seismic event. Therefore, there will be no change in the types or significant increase in the amounts of any ellluents that may be released offsite.
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10.
No Significant increase in Individual or Cumulative Occuoational Radiation Exoosure The three USQs and the extension of the completion date for the seismic upgrades are related to an existing plan for a plant modification that is required by Compliance Plan Issue 36. No increases in individual or cumulative occupational radiation exposures are involved.
Removing the reference to evacuation as an alternative for protecting the safety of the general public following a seismic event is an issue that is only related to exposures resulting from a postulated accident. There is no impact on individual or cumulative occupational radiation exposures.
I 1.
No Significant Constmetion Imnact This change involves an existing plan for a plant modification and only changes the completion date of the project. Therefore, there is no significant construction impact.
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12.
No Significant Increase in the Potential for Radiological or Chemical Consequences from Previousiv Analyzed Accidents As discussed in the response to Item 4, there is no significant increase in the probability of occurrence of previously evaluated accidents. Therefore, there is no significant increase in the potential for radiological or chemical consequences from previously analyzed accidents.
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Page1ofI COMMITMF NTS CONTAINED IN tills SUBMITTAL 1.
Equipment failure calcule. ion based on the final design of the structural modifications were initiated on February 19,1997 and are scheduled to be completed and approved by June 27,1997.
The results of these calculations will be submitted to the NRC to allow the NRC to complete the review and approval process.
2.
The final results of the revised equipment failure calculations are planned to be included in USEC's August 17,1997 SAR Update as required by Compliance Plan Issue 2, " Update the Application Safety Analysis Report."
3.
Consistent with standard practice for upgrading aructures, temporary supports or shoring will be i
used as required and the sequence of removal of old components and installation of new components will be selected based on the stability of the in-process structure. These standard practice techniques account for static and construction-activity dynamic loading, but do not necessarily account for postulated seismic loading.
4.
The project plan for installation of the seismic upgrades in Buildings C-331 and C-335 identifies the need for approximately 2300 lins of structural steel shapes and related materials in each building.
5.
The lins will be hand-rigged (i.e., no crane will be used) and involve structural steel shapes with a length between 20 and 50 feet, weighing less than 5 tons.
6.
The following controls will be applied to each lift associated with the seismic modifications:
Lin time will be minimized to reduce exposure to drop hazards.
Subatmospheric pressures will be maintained within the cascade process equipment.
Lin plans will be prepared and approved in accordance with plant procedures.
Each lift plan will include step-by-step instructions along with appropriate witness and/or inspection hold points.
The lift will be planned from initial rigging, to lift placement, stabilization, and rigging removal. Planning for each lin will include an identification of actions that would be taken in response to a hypothetical load handling accident.
A construction engineer will be assigned to provide dedicated oversight.
7.
In addition to the controls for each lift described above, the following supplemental controls will be applied for each lin that is over, or in proximity to, operating Q or AQ equipment:
Facility owners will be notified prior to the lift An Operations representative will witness the lin and will maintain voice contact with the facility Area Control Room (ACR) throughout the lin to ensure that the ACR is notified as quickly as possible should a load handling accident occur.