ML20137G380
| ML20137G380 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 03/26/1997 |
| From: | Kraft E COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20137G385 | List: |
| References | |
| ESK-97-071, ESK-97-71, NUDOCS 9704010387 | |
| Download: ML20137G380 (9) | |
Text
( kammonw ealth liimn Company Quad Citics Generating Station 22 10 luoth Asenue North Cordm a. ll. 61242 9740 Tcl.W>q224 i ESK-97-071 March 26,1997 United States Nuclear Regulatory Commission Washington, D. C. 20555-0001 Attention:
Document Control Desk
Subject:
Quad Cities Nuclear Power Station Units I and 2 Emergency Application for Amendment to Facility Operating Licenses Pursuant To 10CFR50.9)(a)(5), DPR-29 and DPR-30 Discrepancy in FSAR Value for Secondary Containment Free Volume Docket Nos. 50-254 and 50-265 Pursuant to 10CFR50.90, Comed proposes to amend Facility Operating Licenses DPR-29 and DPR-30 and requests hRC Staff review and approval of an Unreviewed Safety Question resultant from Comed's efrons to reconcile a recently discovered discrepancy in the free volume of the Secondary Containment. As a result ofissues raised during the recent ISI inspection at Dresden Station, Quad Cities identified that the value for Secondary Containment free volume stated in the FSAR is significantly higher than the actual free volume.
To resolve this issue, Comed has completed a Safety Evaluation in accordance with 10CFR50.59. The Safety Evaluation addressed issues potentially affected by the Secondary Containment free volume discrepancy. Comed has concluded that the only significant impact of the discrepancy is an increase in the Control Room cperator dose during an accident condition. This constitutes an Unreviewed Safety Question due to the reduction in the margin of safety as defined in the bases for the Technical Specifications, and due to the increase in the consequences of an accident (10CFR50.59(a)(2)).
Comed proposes to amend Facility Operating Licenses DPR-29 and DPR-30 Technical Specification 3/4.7.P to decrease the allowed methyl iodide penetration for Standby Gas Treatment (SBGT) charcoal from 10% to 2.5%. This will suppon crediting a value of 95% for SBGT charcoal efriciency. By crediting a higher SBGT charcoal efliciency, the Control Room operator dose will decrease to 21.88 Rem to the thyroid, well within GDC 19 requirements. This action resolves both the reduction in safety margin and the increase in the consequences of an accident questions raised by this Unreviewed Safety Question. Note that, consistent with the current Technical Specifications, charcoal filter sampling will be conducted in accordance with Regulatory Guide 1.52 end laboratory testing criteria will be in accordance with ASTM-D-3803-89.
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I USNRC ESK-97-071 2
March 26,1997 1
In addition, Comed proposes to amend Facility Operating Licenses DPR-29 and DPR-30 Technical Specification 5.2.C to reflect the actual calculated volume of Secondary Containment.
Therefore, in accordance with 10CFR50.90, Comed requests review and approval of this proposed license amendment concerning: (1) the reduced value for Secondary Containment free volume and (2) the decrease in the allowed methyl iodide penetration for SBGT charcoal required to mitigate the effects of the reduced free volume. The following outlines Comed's proposed license amendment request.
Attachment A to this letter provides the description and evaluation of the proposed changes to Facility Operating Licenses DPR-29 and DPR-30 for Quad Cities Unit I and Unit 2 and the basis for an emergency approval.
Attachment B provides revised Technical Specification pages.
Attachment C provides the Evaluation of No Significant Hazards Consideration.
Pursuant to 10CFR50.91(a)(5) Comed requests emergency approval of this amendment request to support the return to service of Quad Cities Unit 1. Quad Cities Unit 1 is preparing to return to service after a forced outage. Approval of this emergency amendment is required prior to startup. The basis for this emergency amendment is detailed in Attachment A. The information provided herein has been reviewed by onsite and offsite review in accordance with Company procedures and policies.
To the best of my knowledge and belief, the statements contained above are true and correct. In some respect these statements are not based on my personal knowledge, but obtained information furnished by other Commonwealth Edison employees, contractor employees, and consultants. Such information has been reviewed in accordance with company practice, and I believe it to be reliable.
Comed is notifying the State ofIllinois of this application for amendment by transmitting a copy of this letter and its attachments to the designated state official.
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USNRC l
l ESK-97-071 3
March 26,1997
(
If you have any questions concerning this letter, please contact Charles Peterson, Regulatory Affairs Manager, at (309) 654-2241, extension 3609 Respectfully, ab. L -
E. S. Kraft, J
)
Site Vice President Quad Cities Station Subscribed and Sworn to before me on this J6 day of
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.1997.
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i Notary Public Attachments: A - Background and Evaluation of the Proposed Changes B - Revised Technical Specification Pages C - Evaluation of No Significant Hazards cc:
A. B. Beach, Regional Administrator, Region III R. M. Pulsifer, Project Manager, NRR C. G. Miller, Senior Resident Inspector, Quad Cities W. D. Leech, MidAmerican Enerr;j Company D. C. Tubbs, MidAmerican Energy Company F. A. Spangenberg, Regulatory Affairs Manager, Dresden P. L. Piet, Nuclear Licensing INPG Records Center Oflice of Nuclear Facility Safety, IDNS DCD License (both electronic and hard copies)
ATTACHMENT A DESCRIPTION AND SAFETY ANALYSIS OF THE PROPOSED CHANGES (Page 1 of 5)
Background for the Need for a License Amendment The original design bases for Quad Cities assumed a Secondary Containment free volume of 5,760,000 ft' The calculated free volume of the Secondary Containment is 4,716,000 ff An operability screening and operability determination were made using the guidance provided in Generic Letter 91-18.
The various effects of the discrepancy were analyzed as follows:
A. Control Room Dose Analysis The Seconday Containment free volume is used as an input to the Control Room dose calculation for the purpose ofradionuclide hold-up and mixing prior to release by Standby Gas Treatment (SBGT) and the chimney. The gasses released by SBGT and the chimney are then drawn into the Control Room through the Emergency Filtration Unit. The affect of a smaller Secondary Containment free volume is an increase in Control Room operator dose.
B. Off-Site Dose Analysis The off-site dose calculation is not affected because hold-up time in the reactor building was not used. Leakage from the primay containment was taken directly to SBGT without mixing or hold-up in the Sec mday Containment.
C. RWCU Line Break The affect on Environmental Qualification (EQ) pressures was evaluated by reviewing Bechtel Calculation No. I 13-N-001, Rev.1, "Dresden Units Two & Three Pressure / Temperature (P/T)
Response Following a Reactor Water Cleanup (RWCU) Line Break in the RWCU Heat Exchanger Room" (this calculation evaluated both Dresden and Quad Cities). This calculation is the basis of the reactor building EQ zones. The calculation discusses how the pressure rise is a function of release path through the building and is not sensitive to the building total volume for breaks of this size compared to the secondary containment volume. The reactor building is designed to sustain a 7 inch water gauge internal pressure at the blowout panels on the refuel floor, which ensures that a large margin still exists, since the refuel floor pressure is atmospheric.
As discussed in the calculation, both temperature and pressure increases are not sensitive to total building volume. Therefore, the Secondary Containment free volume reduction does not affect the EQ P/T analysis.
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ATTACllMENT A DESCRIPTION AND SAFETY ANALYSIS OF TiiE PROPOSED CilANGES (Page 2 of 5) 4 l
D. Secondary Containment Sections 6.2.3.3 and 15.6.2.1 of the UFSAR describe a 1 inch instrument line break accident. A decrease in reactor building free volume will not adversely affect the calculated response to this line break because the " Building pressure would adjust to a value such that the volumetric inflow i
of steam would be approximately equal to the combined volume extraction rates of the SBGTS fan, leakage, and steam condensation." Therefore, the pressure increase after an instmment line break is dependent on the available outflow paths, and not dependent on the reactor building free i
volume. Since volume does not affect the resultant pressure, temperature will not be affected either. The volume change does not affect the instrument line break analysis for breaks of this size compared to the secondary containment volume.
i The seven other design bases (UFSAR section 6.2.3.1) are not affected by the volume change.
Two issue screenings were reviewed for Secondary Containment; Problem Identification Form (PIF) 97-0327 for attached piping to the blow out panels and PIF 97-0527 for two broken blow-out panel explosion bolts. In evaluation items C and D above, we established that building pressure as a result ofline breaks is not sensitive to building volume. Therefore the pressure parameters used in these two issue screenings are not affected by the reduction in volume.
i E. Reactor Building Ventilation The Secondary Containment free volume does not affect the normal reactor building ventilation system. The supply and exhaust air flow rates are not affected and thus the design bases i
temperatures (UFSAR section 9.4.7.1) are not affected. The commitment to provide at least one free volume change per hour in the reactor building is still provided. The emergency isolation function is not affected because the trip signals are not affected. The process radiation monitoring trip signal is comprised of the drywell, reactor building vent and refuel floor radiation monitors.
The drywell trip function is not affected because drywell radioactivity is not a function of Secondary Containment free volume. The reactor building vent and icfuel floor concentrations would tend to increase more rapidly during an accident as a resh of the smaller Secondary Containment free volume. This would cause the isolation trips to occur sooner.
ATTACHMENT A DESCRIPTION AND SAFETY ANALYSIS OF THE PROPOSED CIIANGES (Page 3 of 5) l i
Therefore, it was determined that the only impact on the station was a changed input parameter to the l
Control Room dose calculation in the non-conservative direction. The reduction in Secondary Containment free volume does not affect any system functions or interactions. By utilizing newer dose
)
methodology, the GDC limit of 30 Rem thyroid was determined to be met, and the SBGT system was declared operable, but degraded, in accordance with the guidance provided in Generic Letter 91-18.
j Since it is not feasible to physically increase the Secondary Containment free volume to resolve the nonconforming condition, a 10CFR50.59 safety evaluation was performed. This evaluation determined that an Unreviewed Safety Question existed due to the reduction in the margin of safety as defined in the bases for the Technical Specifications, and due to the increase in the consequences of an accident (10CFR50.59(a)(2)).
Basis for Emergency Amendment Comed determined that an Unreviewed Safety Question existed as a result of a discrepancy in the UFSAR value for Secondary Containment free volume. This discrepancy results in a calculated increase 1
in dose to the operators in the Control Room during an accident. This constitutes an Unreviewed Safety Question due to a reduction in the margin to safety and an increase in the consequences of an accident.
Pursuant to 10CFR50.91(a)(5), Comed requests emergency approval of this amendment request to address the Unreviewed Safety Question and to approve a decrease in the methyl iodide penetration for SBGT charcoal allowed by the Technical Specifications. This approval is requested on an emergency basis to support the return to service of Quad Cities Unit 1. Quad Cities Unit 1 is currently ready to return to service after a forced outage. Approval of this emergency amendment is required prior to i
startup.
Therefore, Comed believes that the circumstances described above meet the criteria of 10CFR50.91(a)(5) for review of the proposed amendment on an emergency basis.
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i ATTACIIMENT A DESCRIPTION AND SAFETY ANALYSIS OF TIIE PROPOSED CIIANGES (Page 4 of 5)
Description of the Proposed Channe i
Pursuant to 10 CFR 50.90, Comed proposes to amend Appendix A, Technical Specifications Surveillance Requirements (SRs) 4.7.P.2.b and 4.7.P.3. The purpose of this amendment request is to revise the TS to increase the required SBGT charcoal efliciency, resulting in acceptable dose to the l
Control Room operators during an accident, considering the revised value for Secondary Containment free volume. The current SRs read as follows:
SR 4.7.P.2.b"Each standby gas treatment subsystem shall be demonstrated OPERABLE at least once per 18 months or (1) after any structural maintenance on the HEPA filter of charcoal adsorber housings, or (2) following painting, fire or chemical release in any ventilation zone communicating with the subsystem by verifying within 31 days after removal that a laboratory analysis of a representative carbon sample obtained in accordance with Regulatory Position C.6.b of Regulatory Guide 1.52, Revision 2, March 1978, meets the laboratory testing criteria of ASTM-D-3803-89, for a methyl iodide penetration of <10%, when tested at 30 degrees C and 70 % relative humidity."
SR 4.7.P.3 "Each standby gas treatment subsystem shall be demonstrated OPERABLE after every 1440 hours0.0167 days <br />0.4 hours <br />0.00238 weeks <br />5.4792e-4 months <br /> of charcoal adsorber operation by verifying within 31 days after removal that a laboratory analysis of a representative carbon sample obtained in accordance with Regulatory Position C.6.b of Regulatory Guide 1.52, Revision 2, March 1978, meets the laboratory testing criteria of ASTM-D-3803-89, for a methyl iodide penetration of <10%, when tested at 30 degrees C and 70% relative humidity."
Comed proposes to revise the 10% methyliodide penetration allowed to 2.5% penetration allowed. This will support crediting a 95% filtration efficiency for SBGT.
ATTACHMENT A DESCRIPTION AND SAFETY ANALYSIS OF THE PROPOSED CIIANGES (Page 5 of 5)
In addition, Comed proposes to amend Fac lity Operating Licenses DPR-29 and DPR-30 Technical Specification 5.2.C to reflect the actual calculated volume of Secondary Containment. The current i
Technical Specifications read as follows:
5.2.C "The secondary containment consists of the Reactor Building and a portion of the main steam tunnel and has a minimum free volume of 5,760,000 cubic feet."
Comed proposes to revise the free volume to 4,716,000 cubic feet.
i Bases for Approving the Technical Specification Amendment 4
The smaller free volume in the Secondary Containment results in a lower holdup time, and less mixing in the Secondary Containment following an accident. This causes a higher concentration of activity to be released through the SBGT system, resulting in a higher calculated dose to the Control Room operators.
Using the calculational methodology of record as described in the FSAR (reference NRC Inspection Report 254-91-19 and 265-91-15), it was determined that increasing the credited SBGT charcoal eNeiency to 95% resulted in a Control Room dose of 21.88 Rem to the thyroid. This is an acceptable dose. and well within the GDC 19 limits.
The increase in credit for charcoal efliciency to 95% requires that the test acceptance limit be changed.
Currently, Technical Specification section 4.7.P requires the laboratory analysis of the charcoal sample to 1
meet the testing criteria of ASTM-D-3803-89 for methyliodide penetration ofless than 10%, when tested at 30 deg. C and 70% relative humidity. In order to credit 95% efficiency, the acceptable penetration will be changed to less than 2.5% with all other testing criteria the same. The station procedure for SBGT charcoal testing will be revised to support this change in the Technical Specifications.
The latest SBGT charcoal test results for each train meet the proposed technical specification acceptance criteria. The charcoal in train A tested at a removal efliciency of 99.928% and 99.995% (two samples were submitted), and train B tested at a removal efliciency of 99.969%.
The proposed changes for Technical Specification Section 5.0 are appropriate to reflect the actual calculated free volume of Secondary Containment.
ATTACIIMENT B PROPOSED CIIANGES TO THE TECHNICAL SPECIFICATIONS LICENSES DPR-29 and DPR-30 Remove Insert 3/4.7-24 3/4.7-24 3/4.7-25 3/4.7-25 5-4 5-4 1
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