ML20155H994
| ML20155H994 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 10/30/1998 |
| From: | Krich R COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20155H998 | List: |
| References | |
| NUDOCS 9811100380 | |
| Download: ML20155H994 (11) | |
Text
.. r - -w Commonwealth Edhon Company .
., lee 3 Opus Place
,, Downers Grose, 11, 60515 5701 October 30,1998 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Application for Amendment to Appendix A, Technical Specifications, to Facility Operating Licenses Byron Station, Units 1 and 2 Facility Operating Licenses NPF-37 and NPF-66
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NRC Docket Nos. STN 50-454 and STN 50-455 Braidwood Station Units 1 and 2 Facility Operating Licenses NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Change to Spent Fuel Storage Pool Inadvertent Drain Elevation
References:
(1) K. L. Graesser letter to NRC Document Control Desk dated August 26,1998 replying to Notice of Violation, NRC Inspection Report 50- l 454(455)/98014.
(2) T. J. Tulon letter to NRC Document Control Desk dated June 11, l 1998, replying to Notice of Violation, NRC Inspection Report 50-456(457)/98005.
Pursuant to 10 CFR 50.90, Commonwealth Edison (Comed) proposes to amend Appendix A, Technical Specifications, of Facility Operating Licenses NPF-37, NPF-66, 0g NPF-72 and NPF-77. As committed in References (1) and (2), the proposed amendment h0 requests a change to the Byron and Braidwood Station (B/B) Technical Specifications (TS) Design Features description contained in Section 5.6.2, " Fuel Storage Drainage," to identify the Spent Fuel Pool (SFP) level suflicient to ensure that the Standard Review Plan 9811100300 981030F?
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October 30,1998 Pag'e 2
( U.S. Nuclear Regulatory Commission (SRP) acceptance criteria for inadvertent draining are met while accounting for the failure effects of both the SFP cooling and skimmer loops.
1 TS Design Features Section 5.6.2 states that the spent fuel storage pool is designed and shall be maintained to prevent inadvertent draining of the pool below elevation 423 feet 2 inches for Byron Station, and 423 feet 0 inches for Braidwood Station. As documented in References (1) and (2), the selected elevation was placed in the TS design features description because it represents the general elevation of the anti-siphon hole in the SFP cooling discharge lines at each station. However, neither the skimmer loop nor the j cooling suction line configurations were considered during the initial generation of the TS l value. Upon identification of this condition, a review of the design was initiated. It was concluded that the SFP configuration is a standard Westinghouse design and is in compliance with Regulatory Guide 1.13, and that the SRP acceptance criteria of at least 10 feet above the active fuel was met for potential dewatering scenarios.
As committed in References (1) and (2), a License Amendment Request is being processed herein. Full compliance between the plant configuration and the TS will be achieved with NRC approval of this amendment request to allow revision of the B/B TS to account for the as-built configuration of both the SFP cooling and skimmer loops in setting the SFP l inadvertent drainage level.
This proposed amendment request is subdivided as follows:
- 1. Attachment A gives a description and safety analysis of the proposed change in this amendment.
- 2. Attachments B-1 and B-2 include the marked-up Current Technical Specifications (CTS) Design Features Section 5.6.2, page 5-5, with the requested change indicated for Byron and Braidwood, respectively. Additionally, Attachments B-3 and B-4 include similarly marked-up Improved Technical Specifications (ITS) Design Features Section 4.3.2, page 4.0-2, the subject of which is under separate NRC review.
- 3. Attachment C describes Comed's evaluation performed in accordance with 10 CFR 50.92(c), which confirms that no significant hazards consideration is involved.
- 4. Attachment D provides the Environmental Assessment.
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! October 30,1998
' ' Pag'e 3 U.S. Nuclear Regulatory Commission This proposed amendment has been reviewed and approved in accordance with the requirements of Comed's Quality Assurance Program.
- 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 Omcial.
Please' direct any questions you may have concerning this submittal to David J.
l Chrzanowski at (630) 663-7205 of this omce.- l l
Respectfully, l R. M. Krich Vice President - Regulatory Services Attachments: Amdavit
.A - Description and Safety Analysis B Byron Station CTS mark-ups B Braidwood Station CTS mark-ups B Byron Station ITS mark-ups B Braidwood Station mark-ups C - No Significant Hazards D' - Environmental Assessment.
cc: Regional Administrator - USNRC, Rill NRC Senior Resident. inspector - Byron Station NRC Senior Resident inspector - Braidwood Station Omce of Nuclear Facility Safety - IDNS l
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l STATE OF ILLINOIS )
l COUNTY OF DUPAGE )
l l IN THE MATTER OF )
COMMONWEALTH EDISON (COMED) COMPANY ) Docket Numbers i
l l BYRON STATION UNITS 1 & 2 ) STN 50 454 & STN 50-455 AND )
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BRAIDWOOD STATION UNITS 1 & 2 ) STN 50 456 & STN 50 457 j
SUBJECT:
Change to Spent Fuel Stora:t Pool Inadvertent Drain Elevation I
l AFFIDAVIT I affirm that the content of this transmittalis true and correct to the best of my ;
knowledge, information and belief. !
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/ /
R. M. Krich / !
Vice President - Regulatory Services 1
Subscribed and sworn to before me, a Notary Public in and ;
for the State above named, this 3 day of 0$m ,19 ? T ,
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- e:::::::::::::::::::::: (/ Notary Pub 1ic \
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!: JACQUEUNE T EVANS! l l : l l < l:mwov e r pusu couemason c.sr m or arm rnewws:can4ms <l a s;
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ATTACHMENT A DESCRIPTION AND SAFETY ANALYSIS FOR PROPOSED CHANGE l
A.
SUMMARY
OF PROPOSED CHANGE Pursuant to 10 CFR 50.90, Commonwealth Edison (Comed) proposes to amend Appendix A, Technical Specifications, of Facility Operating Licenses NPF-37, NPF-66, NPF-72 and NPF-77.
The proposed amendment requests a change to Technical Specifications (TS) to revise the Byron l and Braidwood (B/B) Design Features Section 5.6.2, " Fuel Storage Drainage," to identify the Spent Fuel Pool (SFP) level sufficient to ensure that the NUREG-0800 Standard Review Plan (SRP) acceptance criteria for inadvertent draining are met while accounting for the failure effects of both the SFP cooling and skimmer loops. Section 5.6.2 currently states that the spent fuel ;
storage pool is designed and shall be maintained to prevent inadvertent draining of the pool below elevation 423 feet 2 inches for Byron Station, and 423 feet 0 inches for Braidwood Station. As documented in References (1) and (2), the selected elevation was placed in the TS design features description because this value represents the general elevation of the anti-siphon hole in the SFP l
cooling discharge lines at each station. However, the skimmer loop and cooling suction line configurations were not considered during the initial generation of the TS value. NRC approval of this amendment request will allow a B/B TS revision to account for the as-built configuration of both the SFP cooling and skimmer loops in setting the SFP inadvertent drainage level.
In conjunction with NRC approval of the above change, the corresponding description of " Spent i Fuel Pool Dewatering Protection" contained in Section 9.1.3.3 of the B/B Updated Final Safety l Analysis Report (UFSAR) will be clarified to reflect the effects of both the SFP cooling and I skimmer loops in setting the SFP inadvertent drainage level. l l
The proposed change is described in Section E of this Attachment A. The marked-up TS pages l are provided in Attachments B-1 through B-4 for Byron and Braidwood Stations, respectively. i B. DESCRIPTION OF THE CURRENT REQUIREMENTS TS Design Features Section 5.6.2, " Fuel Storage Drainage," currently states that the spent fuel storage poolis designed and shall be maintained to prevent inadvertent draining of the pool below elevation 423 feet 2 inches for Byron Station, and 423 feet 0 inches for Braidwood Station.
C. BASES FOR THE CURRENT REQUIREMENTS 1
- The selected elevation currently placed in the B/B TS Design Features description as the inadvertent drain limit represents the general elevation of the anti-siphon hole in the SFP cooling discharge lines at each station. This feature provides inadvertent drain protection against postulated cooling discharge loop failures. The B/B UFSAR Section 9.1.3.3, " Safety Evaluation,"
i Page 1 of 6 Attachment A dafety Analysis
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discusses spent fuel pool dewatering protection. As currently described, the most serious failure of tliis syste'm would be complete loss of water in the storage pool. System piping is arranged so that failure of any pipeline cannot drain the spent fuel pool below the water level required for adequate radiation shieldmg.
SFP Cooling Loops Anti-siphon Protection The B/B UFSAR Section 9.1.3.2, " System Description," concerning the SFP Cooling System, page 9.136, states for each cooling train that the suction line, which is protected by a strainer, is located at an elevation 4 feet below the normal spent fuel pool water level, while the return line contains an anti-siphon hole near the surface of the water to prevent gravity drainage of the pool.
- (However, the as-built SFP cooling suction lines / strainers are placed approximately 6 % feet below the normal SFP water level reasonably near the normal water level so that the pool cannot be gravity drained given postulated cooling suction loop failures. This discrepancy will be addressed in the UFSAR revision.) Further, the B/B UFSAR Section 9.1.3.3, " Safety Evaluation," i I
page 9.1-41, states that the spent fuel pool cooling pump suction connections enter near the normal water level so that the pool cannot be gravity drained. The return lines contain an anti-siphon hole to prevent the possibility of gravity draining of the pool via these lines.
SFP Skimmer Loops Anti-siphon Protection
, To address the consequences of skimmer suction flexible hose degradation, the Braidwood Station l
' SFP skimmer loop suction piping has recently been provided with an anti-siphon hole for protection similar in design to that afforded the SFP cooling discharge piping discussed above.
The modification to the Braidwood SFP skimmer / suction included drilling an anti-siphon hole in j the skimmer suction piping at elevation 423' 4%", near the normal SFP water level to provide l gravity drain protection against potential suction side failure scenarios. Byron Station is currently
! evaluating a similar change. Additionally, the skimmer loops discharge into the SFP at 418' 3M" I and 418' 3%" elevation at Byron, and at 419' 1" and 418' 8" elevation at Braidwood. This corresponds to an approximate 5 to 6 foot submergence without an anti-siphon hole. This is reasonably near the surface and provides adequate anti-siphon protection similar to the cooling suction design.
L . The anti-siphon protection design of both the SFP cooling and clean-up piping was reviewed and found to be acceptable as documented in NUREG-0876, Byron SER Section 9.1.3, page 9-5, which states that "all connections to the spentfuelpool are either near the normal water level or areprovided with antisiphon holes to precludepossible siphon draining ofthepool water. " This review is applicable to Braidwood as documented in NUREG-1002, Braidwood SER. The
- conclusion reached is that submergence of SFP piping connections near the surface without an l anti-siphon hole or the use of an anti-siphon hole for protection of SFP piping connections at deeper submergence levels provide adequate protection.
SRP Section 9.1.3, " Spent Fuel Pool Cooling and Cleanup System," (Reference 3) Review l Procedures, Paragraph Ill.1.e states: "The spentfuelpool and cooling systems have been designed so that in the event offailure ofinlets, outlets, piping, or drains, thepoollevel will not be inadvertently drained below a point approximately 10 feet above the top of the activefuel. Pipes or externallines Page 2 of 6 Attachment A-Safety Analysis u . ,
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l extending into thepool that are equipped with siphon breakers, check valves, or other devices to prevent drainage are acceptable as a means ofimplementing this requirement." These requirements iormed \
l the basis for the B/B SFP piping configuration.
l D. NEED FOR REVISION OF THE REQUIREMENT As described in References (1) and (2), a discrepancy currently exists between the stated B/B TS ;
Design Features Section 5.6.2, " Fuel Storage Drainage," SFP inadvertent drain elevation and the '
existing design siphon capability. The selected elevation was placed in the Design Features ,
description because this value generally represents the elevation of the anti-siphon hole in the SFP l
cooling discharge lines at each station. However, neither the skimmer loop nor the cooling l
suction line configurations were considered during the initial generation of the TS value.
l Approval of this amendment request will revise the B/B TS inadvertent drainage level to account l l for the as-built configuration of both the SFP cooling and skimmer loops while ensuring the SRP l acceptance criteria are met.
In addition, the description of the B/B UFSAR Section 9.1.3.3, " Safety Evaluation," will be clarified to address the effects of both the SFP cooling and skimmer loop configurations.
Approval of the B/B TS change described below will allow for the appropriate B/B UFSAR text to be updated and restore consistency of both plants with their licensing basis. l E. DESCRIPTION OF THE PROPOSED CHANGE B/B TS Design Features Section 5.6.2, " Fuel Storage Drainage," inadvertent drainage elevations are being revised from 423 feet 2 inches for Byron, and 423 feet 0 inches for Braidwood, to 410 feet 0 inches for both stations. This SFP level is sufficient to ensure that the SRP acceptance criteria are met while accounting for the potential effects of all SFP cooling and skimmer loop inadvertent drain scenarios.
F. SAFETY ANALYSIS OF THE PROPOSED CHANGE SRP Section 9.1.3," Spent Fuel Pool Cooling and Cleanup System," Acceptance Criteria 1.g.(4) requires "the capability to prevent reduction infuel storage coolant inventory under accident conditions in accordance with the guidelines ofposition C.6 ofRegulatory Guide 1.13." Regulatory Guide 1.13,
" Spent Fuel Storage Facility Design Basis" (Reference 4), Regulatory Position C.6 states that
" drains, permanently connected mechanical or hydraulic systems, or otherfeatures that by maloperation orfailure could cause loss ofcoolant that would uncoverfuel should not be installed or included in the design. Systemsfor maintaining water quality and quantity should be designed so that any maloperation orfailure ofsuch systems will not causefuel to be uncovered." Tbe B/B UFSAR Appendix A commitment to Regulatory Guide 1.13 states that the plant design conforms to the requirements of Revision 1 of this guide as presented in Subsections 9.1.2.3 and 9.1.3.3.
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Page 3 of 6 Attachment A -Safety Analysis
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1 As stated in B/B UFSAR Subsection 9.1.3.3, " Spent Fuel Pool Dewatering Protection," system piping is arranged so that failure of any pipeline cannot drain the spent fuel pool below the water level required for adequate radiation shielding. This shielding requirement continues to be met I with this proposed B/B TS change. The existing anti-siphon design of both the SFP cooling and I skimmer loops described in Section C above protects the SFP against inadvertent siphoning below l the water level required for adequate radiation shielding.
SFP Dewatering Incidents The most limiting postulated SFP dewatering incidents discussed in B/B UFSAR Section 9.1.3.3 involve SFP drainage to (a) a dry transfer canal, (b) a dry transfer canal and cask fill area, and (c) a dry transfer canal and cask fill area which additionally communicates through an open transfer tube to an empty refuel cavity. The initial conditions of these dewatering incidents assume approximately 26 feet of water above the top of the active region of the spent fuel assemblies.
This corresponds to the SFP low level alarm elevation and ensures that sufficient shielding remains over the fuel after any postulated spent fuel pool dewatering incident to allow recovery I operatic .s to continue. These dewatering incidents involve initiating circumstances / failures such i I
as accidental gate openings, gate seal failures, or an open transfer tube. The initial conditions of the dewatering incident analysis are not affected by this proposed TS change as they are not taken coincidentally with the additional dewatering effects of postulated SFP cooling or skimmer loop piping / component failures. The current dewatering incident shielding analysis and resultant' water levels over the spent fuel remain valid.
SFP Fuel Handling Accidents The minimum water depth between the top of damaged fuel rods and the SFP surface is one of the key parameters used in the fuel handling accident analyses described in the B/B UFSAR Subsection 15.7.4, " Fuel Handling Accidents." For this parameter, Table 15.7-7 assumes the minimum depth is greater than or equal to 23 feet. The B/B Refuel Operations TS LCO 3.9.11 ensures this 23-foot depth is maintained. If this minimum specified depth is not satisfied, all fuel movement and crane operations with loads are suspended and the water level is restored.
Therefore, any potential dewatering effects from postulated SFP cooling or skimmer loop piping / component failures would be detected and addressed by the required LCO Actions ensuring that fuel handling analyses remain unaffected.
Bounding Inadvertent Drain Elevation In determining the bounding inadvertent drain down elevation due to potential SFP cooling and skimmer loop failures, the reference SFP elevations are provided in Attachment A, Table 1. The maximum potential inadvertent drain down elevation due to gravity siphoning from either the SFP cooling or skimmer loop failures is 415' %" at Byron Station due to the siphoning impact of the skimmer suction (without an anti-siphon hole), and 417' 9 3/8" at Braidwood Station due to i
the siphoning impact of the cooling suction lines. The existing SFP configuration is in compliance with the SRP acceptance criteria. The anti-siphon protection ensures that inadvertent i drainage can not occur below at least 10 feet above the top of the active fuel, that suitable Page 4 of 6 Attachment A Safety Analysis
shielding is maintained by a minimum water level above the fuel, and that fuel uncovering due to system maloperation or failure is prevented.
The revised B/B TS inadvertent drain limit is being proposed to conservatively bound all SFP cooling and skimmer loop failures, under any maloperation or failure scenario. The proposed B/B TS inadvertent drain limit of 410 feet 0 inches meets the SRP acceptance criteria of being at
. least 10 feet above the top of the active fuel to maintain adequate radiation shielding, and bounds the siphon potential from all submerged cooling and skimmer loops.
G. IMPACT ON PREVIOUS SUBMITTALS On December 13,1996, Comed submitted a request for conversion from the Byron and Braidwood Current Technical Specifications (CTS) to Improved Technical Specifications (ITS).
The impact of the proposed change on the ITS conversion is similar to the impact on the CTS.
The affected ITS pages are being provided along with the affected CTS pages in Attachment B, and will be similarly addressed in separate ITS submittal and/or correspondence to the NRC as needed.
H. SCHEDULE REQUIREMENTS Although no specific schedule requirements for this submittal were established in References (1) and (2), due to the technical nature of the change involved, a less than 6-month approval cycle is requested.
I. REFERENCES
- 1. K. L. Graesser letter to NRC Document Control Desk dated August 26,1998 replying to Notice of Violation, NRC Inspection Report 50-454(455)/98014.
- 2. T.J. Tulon letter to NRC Document Control Desk datedJune 11,1998, replying to Notice of Violation, NRC Inspection Report 50-456(457)/98005.
- 3. NUREG-0800 "NRC Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, LWR Edition," Section 9.1.3, Revision 1 dated July 1981.
- 4. NRC Regulatory Guide 1.13 " Spent Fuel Storage Facility Design Basis," Regulatory Position C.6, Revision 1 dated December 1975.
t Page 5 of 6 Attachment A Safety Analysis
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TABLE 1 Spent Fuel Pool Reference Elevations Description Braidwood Byron
- 1. SFP Hi-level Alarm 424' 9" 424' 9 % "
- 2. Normal SFP Water Level Between Hi & Lo Between Hi & Lo
- 3. SFP Lo-level Alarm 424' 2" 424' 2"
- 4. Cooling Discharge Lines Anti-Siphon Hole 423' 5" 423' 1H"
- 5. Skimmer Suction Lines Anti-Siphon Hole 423' 4 % " N/A-
- 6. Current TSInadvertent Drain Limit 423' 0" 423' 2"
- 7. Skimmer Discharge Return Lines 419' 1" 418' 3M" 418' 8" 418' 3 % "
- 8. Cooling Suction Lines / Strainers 417' 9 3/8" 417' 9 % "
- 9. Maximum Skimmer Loop Suction 410' 6 % " 415' 3" 415' %"
- 10. Proposed TS Inadvertent Drain Limit 410' 0" 410' 0"
- 11. Nominal Top of Active Fuel 398' 8" 398' 8" (FailedFuel Canisters)
- 12. Nominal Top of Active Fuel 398' 1" 398' 1" (Spent FuelRacks) l i
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l Page 6 of 6 Attachment A-Safety Analysis
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ATTACHMENT B 1 MARKED UP PAGE FOR PROPOSED CHANGE TO CURRENT TECHNICAL SPECIFICATIONS (CTS)
BYRON STATION UNITS 1 & 2 CHANGE TO SPENT FUEL STORAGE POOL INADVERTENT DRAIN ELEVATION REVISED PAGE:
5-5 REVISED PARAGRAPH:
5.6.2 1
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Page 1 of 8 Attachment A-Safety Analysis i
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