ML15236A018
ML15236A018 | |
Person / Time | |
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Site: | San Onofre ![]() |
Issue date: | 08/20/2015 |
From: | Palmisano T J Southern California Edison Co |
To: | Document Control Desk, Office of Nuclear Reactor Regulation |
References | |
Download: ML15236A018 (39) | |
Text
" I E ISO NThomas J. Palmisano
"'""SOUTHERN CALIFORNIA Vice President Decommissioning
&i Chief Nuclear OfficerEDISON: _An EDISON INTERNATIONAL CompanySan Onofre Nuclear Generating StationAugust 20, 2015 10 CFR 50.90U. S. Nuclear Regulatory Commission ATTN: Document Control DeskWashington, D.C. 20555
Subject:
Docket Nos. 50-361 and 50-362Amendment Applications 270 and 255Proposed Changes to Specific Regulatory Guide Commitments San Onofre Nuclear Generating
- Station, Units 2 and 3
References:
(1) Letter from P. T. Dietrich (SCE) to the U. S. Nuclear Regulatory Commission (NRC) dated June 12, 2013;
Subject:
Certification of Permanent Cessation of Power Operations San Onofre Nuclear Generating
- Station, Units 2 and 3(2) Letter from P. T. Dietrich (SCE) to the U.S. Nuclear Regulatory Commission (NRC) dated June 28, 2013;
Subject:
Permanent Removal of Fuel from theReactor Vessel, San Onofre Nuclear Generating Station Unit 3(3) Letter from P. T. Dietrich (SCE) to the U.S. Nuclear Regulatory Commission (NRC) dated July 22, 2013;
Subject:
Permanent Removal of Fuel from the*Reactor Vessel, San Onofre Nuclear Generating Station Unit 2
Dear Sir or Madam:
Pursuant to 10 CFR 50.90, Southern California Edison (SCE) hereby submits licenseamendment application 270 to operating license NPF-10 for San Onofre Nuclear Generating Station (SONGS) Unit 2 and license amendment 255 to operating license NPF-15 for SONGSUnit 3. These License Amendment Requests consist of Proposed Change Number (PCN)-609.
In Reference 1, SCE provided certification of SONGS Units 2 and 3 permanent cessation of power operation.
In References 2 and 3, SCE submitted certifications ofpermanent removal of fuel from the reactor vessels for SONGS Units 3 and 2. Consequently, the 10 CFR Part 50 licenses for SCE no longer authorizes operation of the reactor oremplacement or retention of fuel into the reactor vessel, as specified in 10 CFR 50.82(a)(2).
The amendment proposes revisions to Appendix 3A of the Updated Final Safety AnalysisReport to more fully reflect the permanently shutdown status of SONGS Units 2 and 3. Therevision will include a limited set of exceptions and clarifications of referenced Regulatory Guides to reflect the significantly reduced decay heat loads in the SONGS Units 2 and 3 SpentFuel Pools and to support corresponding design basis changes.
Because these changes arelimited in scope, and beneficial to the safety of decommissioning personnel, SCE is requesting approval of this amendment within six months.P.O. B~ox 430San Clemente, CA 92674 k(949) 368-6575Fax: (949) 368-9881Tom.Palmisano@sce.com Document Control Desk-2Aust0, 01-2-August 20, 2015There are no new regulatory commitments in this letter or the Enclosure.
Should you have any questions, or require additional information, please contactMr. Jim Kay, Manager, Nuclear Regulatory Affairs at (949) 368-7418.
I declare under penalty of perjury that the foregoing is true and correct.Executed onSincerely,
Enclosures:
PCN-609 with Attachments cc: M. Dapas, Regional Administrator, NRC Region IVT. Wengert, NRC Project Manager, SONGS Units 2 and 3R. Kellar, NRC Region IV, Branch Chief, Repository and Spent Fuel SafetyM. Vaaler, NMSS Project ManagerS. Y. Hsu, California Department of Public Health, Radiologic Health Branch ENCLOSURE EVALUATION OF AMENDMENT PCN-609Proposed Changes to Specific Regulatory Guide Commitments Spent Fuel Pool Cooling and Make-up Design1. SUMMARY DESCRIPTION
- 2. DETAILED DESCRIPTION 2.1 Regulatory Guide 1.13, 1.29, and 1.76 Exceptions 2.2 Discussion on Applicability of Regulatory Guide 1.263. TECHNICAL EVALUATION
3.1 Background
3.2 Discussion
3.3 Remaining Safety Function3.4 Seismic Category III Design Details3.5 Schedule and Resource Impacts3.6 Precedents
- 4. REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria 4.2 No Significant Hazards Consideration
4.3 Conclusions
- 5. ENVIRONMENTAL CONSIDERATION
- 6. REFERENCES ATTACHMENTS:
A. Spent Fuel Pool 'Island' Description B. Proposed Exceptions to SONGS Units 2/3 UFSAR Appendix 3A -Mark-ups Document Control Desk-2-2-1.0 SUMMARY DESCRIPTION Introduction Southern California Edison Company (SCE) intends to implement a series of modifications toSONGS Units 2 and 3 to implement
'cold and dark' as noted in the Post-Shutdown Decommissioning Activities Report (PSDAR).
The fundamental purpose of achieving
'cold anddark' is to improve site personnel safety by reducing the possibility of interactions with energized electrical equipment or in-service piping or tubing. The following systems are among thosenecessary to be installed in order to implement all the 'cold and dark' activities:
- 1) Independent Spent Fuel Pool Cooling Systems (ISFPCS or also referred to as the Spent Fuel Pool 'Island'),
- 2) Enhanced Spent Fuel Pool Makeup System, and 3) Decommissioning Power Ring System.Substantive delays in these modifications impact other aspects of 'cold and dark' as discussed in Section 3.5.The Spent Fuel Pool Island is designed to Seismic Category III requirements.
The EnhancedSpent Fuel Pool Makeup System is designed to Seismic Category I. This is consistent withNUREG-0800, Standard Review Plan (SRP), Section 9.1.3 -Spent Fuel Pool Cooling andCleanup System as detailed in Section 3.1.The Spent Fuel Pool Island provides cooling to the spent fuel pools using a configuration thateliminates reliance on support systems.
The Make-up System provides water to the spent fuelpool to compensate for evaporative losses or inadvertent draining.
Both of these and other 'coldand dark' systems will be powered by a new non-safety, Seismic Category Ill electric system.To implement these modifications as designed, SCE will need to take exceptions to some of theRegulatory Guides as listed in the SONGS Units 2 and 3 Updated Final Safety Analysis Report(UFSAR).
SCE is requesting that these exceptions to the Regulatory Guides be reviewed andapproved by the NRC. These additional exceptions to the Regulatory Guides are based on thefollowing:
- The current decommissioning plant status,* The reduction in spent fuel pool heat loads,* Significantly increased required response times for implementing mitigating actions,* Potential radiation dose release to the public that is now well below current acceptance
- criteria, and* The remaining safety function is protection of the spent fuel cladding which is achievedby maintaining water level in the pool.Description of the License Amendment Request (LAR)SCE is proposing to take additional exceptions to Regulatory Guides 1.13, 1.29, and 1.76beyond those currently listed in Appendix 3A of the UFSAR to more fully reflect thedecommissioning plant status; particularly the significantly reduced spent fuel decay heat load.Appendix 3A contains a compiled list of NRC Regulatory Guides which SONGS utilized in theoriginal design of SONGS Units 2 and 3. In particular the introduction to the Appendix states:"This appendix discusses the conformance of plant design with the guidelines presented in certain NRC Regulatory Guides. A reference to the FSAR section in which theapplicable design features are described is also provided.
Where the design differs from Document Control Desk---3-the Regulatory Guide, alternate methods of providing an equivalent level of safety havebeen utilized; these differences are discussed or reference is made to the appropriate FSAR section for detailed implementation.
In general, compliance with Regulatory Guides 1.1 through 1.96 was assessed duringthe design and construction phase of Units 2 and 3. Subsequently, Regulatory Guideshave been assessed on a case-by-case basis."This Appendix currently addresses Regulatory Guides through 1.197.Current Installation PlanThe Spent Fuel Pool Island will be installed under a System Temporary Modification using 10CFR 50.59 and administratively processed in compliance with appropriate plant procedures.
This will allow authorized work to continue in parallel to the review of this LAR. Once the Islandis in operation, the current Spent Fuel Pool cooling system will remain available until approval ofthis LAR. Once this LAR is approved, the Island will be made permanent and the existingsystem removed from operation and eventually retired.The intent is to install, test and provide run-in time with the Island prior to removing the currentsystem from operation.
Plant procedures will address transition between systems whichinvolves pump start/stop and the repositioning of valves to direct the in-service system throughthe common discharge.
The significant reduction in spent fuel decay heat levels and offsitedose consequences allows for alternative design requirements relative to the cooling systemused during operation without increasing the likelihood or consequences of accidents.
Appropriate description for the ISFPCS and enhanced Spent Fuel Pool Makeup System isprovided in Attachment A for information and as background and context for the LAR.Therefore, this LAR requests NRC acceptance of the proposed exceptions to referenced Regulatory Guides to allow the ISFPCS to fully replace and allow the eventual retirement of theSEP05 and support systems.
In particular, the scope of this LAR encompasses and is limitedto the following proposed exceptions:
- The change from a Seismic Category I SFPCS to a Seismic Category III (California Building Code) ISFPCS that is potentially subject to impact from tornado missiles.
- The change from a configuration with diesel backed Seismic Category I electrical powersources for the spent fuel pool cooling and make-up system to a diesel backed powersource which is designed to Seismic Category III criteria and not fully protected fromtornado missiles.
2.0 DETAILED DESCRIPTION 2.1 Regulatory Guide 1.13, 1.29, and 1.76 Exceptions Regulatory Guides 1.13, 1.29, and 1.76 identify design and quality criteria for various systems,including the spent fuel cooling and make-up systems and the associated power supplies.
Thefollowing provides excerpts from the revision of the Regulatory Guides that SONGS Units 2 and Document Control Desk-4-4-3 are currently conformed with and also details what SCE is proposing to change or takeexception to the current content.Regulatory Guide 1.13, Revision 1, "Spent Fuel Storage Facility Design Basis"Discussion includes the following statements:
"General Design Criterion 61, "Fuel Storage and Handling Criteria for Nuclear PowerPlant," "of Appendix A, "General Design Criteria for Nuclear Power Plants, "to 10 CFRPart 50, "Licensing of Production and Utilization Facilities, "requires that fuel storage andhandling systems be designed to assure adequate safety under normal and postulated accident conditions."
"If spent fuel storage facilities are not located within the primary reactor containment or*provided with adequate protective
- features, radioactive materials could be released tothe environs as a result of either loss of water from the storage pool or mechanical damage to fuel within the pool.""A4 permanent fuel-pool-coolant makeup system with a moderate capability, and withsuitable redundancy or backup, could prevent the fuel from being uncovered if suchleaks should occur."Regulatory Position includes the following statements:
C.8"A Seismic Category I makeup system should be provided to add coolant to the pool.Appropriate redundancy or a backup system for fifling the pool from a reliable source,such as a lake, river, or onsite Seismic Category I water-storage
- facility, should beprovided.
If a backup system is used, it need not be permanently installed system. Thecapacity of the makeup systems should be such that water can be supplied at a ratedetermined by consideration of the leakage rate that would be expected as the result ofdamage to the fuel storage pool from the dropping of loads, from earthquakes, or frommissiles originating in high winds."Proposed SONGS Units 2 and 3 Exceptions and Clarifications 0.8The Decommissioning-Phase Spent Fuel Pool Inventory Make-up System will be hard-piped and designed to Quality Group lII-AQ and Seismic Category I. The enhancedSpent Fuel Pool Make-up System will be powered by a commercial Seismic Category IllDecommissioning Power Ring System.As discussed in detail below, these classifications are acceptable because the currentand future decay heat conditions in the SONGS Units 2 and 3 pools afford much greatertime to respond to any threats to functional capability of the ISEPCS or enhanced SpentFuel Pool Make-up System, with proven manual action mitigation measures being ableto be implemented in less than two hours.
Document Control Desk---5-Regulatory Guide 1.29, Revision 1, "Seismic Design Classification" Introduction includes the following statements:
"General Design Criterion (GDC) 2, "Design Bases for Protection Against NaturalPhenomena,"
of Appendix A, "General Design Criteria for Nuclear Power Plants,"
to Title10, Part 50, of the Code of Federal Regulations (10 CFR Part 50), "Domestic Licensing of Production~and Utilization Facilities" (Ref. 1), requires that nuclear power plantstructures,
- systems, and components (SSCs) important to safety must be designed towithstand the effects of earthquakes without loss of capability to perform their safetyfunctions."
"These plant features are those necessary to assure (1) the integrity of the reactorcoolant pressure
- boundary, (2) the capability to shut down the reactor and maintain it ina safe shutdown condition, or (3) the capability to prevent or mitigate the consequences of accidents that could result in potential offsite exposures comparable to the guideline exposures of 10 CFR Part 100."Regulatory Position includes the following statements:
Regulatory Position 0.1"The following structures,
- systems, and components of a nuclear power plant, including their foundations and supports, are designated as Seismic Category
/ and should bedesigned to withstand the effects of the SSE and remain functional.
The pertinent qualityassurance requirements of Appendix B to 10 CFR Part 50 should be applied to allactivities affecting the safety-related functions of these structures,
- systems, andcomponents.
(d) Systems or portions of systems that are required for (1) reactor shutdown, (2)residual heat removal, or (3) cooling the spent fuel storage pool.(g) Cooling water, component
- cooling, and auxiliary feedwater systems or portions ofthese systems, including the intake structures, that are required for (1) emergency core cooling, (2) post-accident containment heat removal, (3) post-accident containment atmosphere
- cleanup, (4) residual heat removal from the reactor, or (5)cooling the spent fuel storage pool.(/) The spent fuel storage pool structure, including the fuel racks.(r) The Class 1E electrical
- systems, including the auxiliary systems for the onsiteelectric power supplies, that provide the emergency electric power needed forfunctioning of plant features included in items l.a through 1.q above."
Document Control Desk---6-Proposed SONGS Units 2 and 3 Exceptions and Clarifications 0.1Based on the relatively low levels of decay heat being generated by the spent fuel storedin the spent fuel pools and the substantial amount of time to take mitigating actions inthe event of loss of spent fuel pool cooling, the spent fuel pool cooling systems;associated support systems; and associated power systems are Seismic Category Ill.Additionally, the ISFPCS will be designed to Seismic Category Ill standards.
Suchstandards require protection against the earthquakes specified in the California buildingcode, which provides an adequate degree of seismic restraint.
Regulatory Guide 1.76, Revision 0, "Design-Basis Tornado and Tornado Missiles forNuclear Power Plants"Introduction includes the following statements:
"General Design Criterion 2, "Design Bases for Protection Against Natural/Phenomena,"
of Appendix A, "General Design Criteria for Nuclear Power Plants,"
to 10 CFR Part 50, -"Licensing of Production and Utilization Facilities,"
"requires, in part, that structures,
- systems, and components important to safety be designed to withstand the effects ofnatural phenomena such as tornadoes without loss of capability to perform their safetyfunctions.
Criterion 2 also requires that the design bases for these structures, systems,and components reflect (1) appropriate consideration of the most severe of the naturalphenomena that have been historically reported for the site and surrounding region, withsufficient margin for the limited accuracy and quantity of the historical data and theperiod of time in which the data have been accumulated, (2) appropriate combinations ofthe effects of normal and accident conditions with the effects of the natural/phenomena, and (3) the Importance of the safety functions to be performed."
Regulatory Position includes the following statements:
"I. Nuclear power plants should be designed to withstand the Design Basis Tornado(DBT). The values of the parameters specified in Table / for the appropriate regions ofFigure / are generally acceptable to the Regulatory staff for defining the DBT for anuclear power plant. Sites located near the general boundaries of adjoining regions mayinvolve additional consideration."
Proposed SONGS Units 2 and 3 Exceptions and Clarifications SONGS proposes to take exception to this Regulatory Guide for the ISFPCS secondary cooling components because they will not perform a safety-related function.
Based onthe relatively low levels of decay heat being generated by the spent fuel stored in thespent fuel pools and the substantial amount of time available to take mitigating actions(which can be implemented in less than two hours) in the event of loss of spent fuel poolcooling, it is not necessary for the spent fuel pool cooling systems, associated supportsystems, or associated power systems to withstand tornado missiles.
In addition, due tothe reduced SEP makeup functional requirements included above, it is not necessary forthe associated SFP makeup power systems to withstand tornado missiles.
Document Control Desk-7-7-The ISFPCS has some inherent protection against tornados.
The 1SFPCS (Island)primary loop equipment is protected against tornado missiles.
- However, the secondary cooling system is outside at grade level. It is sheltered on East and West by a hill andbuilding respectively.
To the North and South, the Secondary Cooling equipment islocated in a recess between the two Fuel Handling Buildings reducing the vulnerability totornado missiles.
The cooling units are designed to the California Building Code windloading requirement of 115 mph.The design basis wind speed results in a failure probability of less than 6 E-4 per year.This is based on ASCE 7-10 (Reference 6.21 ) Figure 26.5-1 B, wind speeds correspond to approximately a 3% probability of failure in 50 years (or 6 E-4 per year).2.2 Discussion on Applicability of Regulatory Guide 1.26Regulatory Guide 1.26 provides criteria for designating the Quality Group of various plant SSCs.Existing changes in SSC classifications have been made consistent with the guidancepresented in the Regulatory Guide and the SONGS Units 2 and 3 permanently defueled state.As discussed below, NRC has approved a change in the Quality Group of plant SSCs. Theexceptions to Regulatory Guide 1.26 in UFSAR Appendix 3A are shown in Appendix B to reflectthat approval.
In the Permanently Defueled Technical Specification (PDTS) License Amendment Request(Reference 6.8) SCE provided the following as the basis for deleting TS 5.5.2.10, Inservice Inspection and Testing Program:"....is being deleted because the Inservice Inspection and Testing Program is no longerrequired in a permanently defueled condition.
There are no longer any ASME CodeClass 1, 2, or 3 components or Code Class CC and MC components that are required toperform a specific function in mitigating the consequences of an accident when in apermanently defueled condition."
The NRC Safety Evaluation (Reference 6.4) supporting the Amendment issued in response tothe PDTS LAR responded as follows:"TS 5.5.2.10, "lnservice Inspection and Testing Program,"
establishes the con trols forperiodic inspection and testing of the American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 pumps and valves in accordance with the ASMEOperation and Maintenance Code. These code classes protect equipment relied upon toprevent and mitigate DBAs. The licensee proposed to delete this program since there isno longer any ASME Code Class 1, 2 or 3 pumps and valves, or Code Class CC or MCcomponents in the SONGS Units 2 and 3 inservice inspection and testing program thatcontinue to operate and perform a specific function in mitigating the consequences of areactor accident due to the permanently shutdown and defueled status of the plants.Because the licensee is prohibited from operating the plant or placing fuel in the reactorvessel, in accordance with 10 CFR 50.82(a)
(2), there are no longer any ASME Codeclass pumps and valves that remain in operation and are to be relied upon to mitigate aDBA. As such, the inservice inspection and testing program is no longer relevant toSONGS Units 2 and 3, given the permanently shutdown and defueled status of thesefacilities.
The NRC staff also notes that the licensee shall continue to monitor the Document Control Desk-8-8-performance and condition of all SSCs associated with the storage,
- control, ormaintenance of spent fuel in in a safe condition and with reasonable assurance thatthese SSCs are capable of fulfilling their intended functions, pursuant to 10 CFR 50.65,""Re quirements for monitoring the effectiveness of maintenance at nuclear powerplants."
Therefore, the NRC staff finds that the licensee's proposed change to delete TS5.5.2.10, Inservice Inspection and Testing Program, appropriately reflects the change inplant status, and is acceptable."
Thus, the NRC has already approved the change in ASME class and Quality Groupclassification of plant SSCs using the change in plant status as an adequate basis for no longerclassifying pumps and valves or components in accordance with the ASME code. It isappropriate to modify the existing exceptions to Regulatory Guide 1.26 as proposed in the mark-up to Appendix 3A as shown in Attachment B to this LAR for conformance with the approval ofthe PDTS. These Regulatory Guide 1.26 changes are provided for completeness of thediscussion only and further NRC approval is not needed or requested as part of this LAR.3.0 TECHNICAL EVALUATION
3.1 Background
As previously noted, the fundamental reasoh for seeking NRC acceptance of these changes isto facilitate the transition from the current Spent Fuel Pool Cooling System (and its supportsystems) to a new Independent Spent Fuel Pool Cooling System (and its support systems).
Design details and description of the ISFPCS are attached in Appendix A. These design detailsare consistent with SCE responses to NRC staff's questions during its review of thePermanently Defueled Emergency Plan (PDEP) to address the adequacy of the then currentand proposed Spent Fuel Pool cooling systems in RAI-16 (Reference 6.7).UFSAR Appendix 3A, as is the case for the historic design and licensing basis of SONGS, isgenerally based on operating plant conditions.
Spent fuel pool conditions change when fuel isno longer being irradiated and discharged to the pools. Instead of a relatively stable cyclic setof circumstances from one refueling outage to another involving relatively high decay heatloads. Following permanent removal of the fuel from the reactors, the pools transition over timeto a relatively low decay load with no new spent fuel being added to the pools. Challenges based almost completely on the impact of the most recently discharged fuel or the potential need for a full-core off-load are no longer present.
This beneficially impacts response times,heat-up rates and radiological dose consequences.
The scope and radiological consequences of accidents possible at SONGS Units 2 and 3 aresubstantially lower than those at an operating plant. There are at least two primary reasons forthis reduction in radiological consequences.
- 1. Analyses of accidents in spent fuel pools are generally dominated by the impacts fromrecently discharged fuel (last refueling batch and a full-core off-load),
because radioactive decay of spent fuel decreases rapidly following shutdown of the reactor.
The latestdischarge to the SONGS Units 2 and 3 pools was sufficiently long ago (more than 31/2, yearsago) as to greatly reduce these contributions from the most recently discharged spent fuel.
Document Control Desk-9-9-2. All the fuel stored has passed its initial decay. Short lived isotopes are no longer present inanything above negligible values. This reduces their contribution to radiation source termand decay heat.These changes are a natural outgrowth of the changes in fuel characteristics since its lastirradiation.
The NRC has acknowledged these changes generically (Reference 6.9) and on aplant-specific basis. The discussion below focuses on the plant-specific aspects.In the SER (Reference 6.5) approving the PDEP, the NRC indicated the following relative totheir review of the PDEP in response to RAI 16:"3.2.1.1 Licensee Contfrol of Changes During Decommissioning In the enclosure to the SCE letter dated November 3, 2014, the licensee responded tothe NRC staff's RAI regarding control of changes to spent fuel storage conditions throughout the decommissioning
- process, including conformance with the IndustryDecommissioning Comments (IDCs) and Staff Decommissioning Assumptions (SDAs).The licensee stated that design changes and installation activities would be contfrolled incompliance with standard design change processes including 10 CFR 50. 59, whichapplies to changes to the facility design and operation as described in the SONGSUFSAR. The licensee also stated that the NUREG-1738 SDAs and IDCs are included inthe SONGS UFSAR, and are thereby addressed by the design change processes.
Furthermore, the licensee detailed planned changes to the design of systems interfacing with the SFP, including the redundancy, electric power supply, seismic design class, andquality group applicable to the SFP forced cooling and primary makeup systems.
TheNRC staff has reviewed the licensee's response and finds that the proposed changecontrol mechanism would be in compliance with 10 CFR 50.59, which is the appropriate NRC regulation for that activity, and the planned changes affecting the reliability ofsystems interfacing with the SEP are commensurate with the reduced likelihood of fueloverheating should the function of those systems be impaired."
The Spent Fuel Pool 'Island' and the Enhanced Spent Fuel Pool Makeup System has beendesigned to meet the intent of the applicable parts of NUREG-0800, Standard Review Plan,Section 9.1.3 -Spent Fuel Pool Cooling and Cleanup System. These changes provide thebasis for taking the exceptions to requirements in Regulatory Guides 1.13 and 1.76. Detailsaddressed in this LAIR include:*The spent fuel pool Make-up System and its source is Seismic Category I and the SEPIsland is designed to Seismic Class Ill. However, based on recently approvedclassification changes at SONGS, the SEP Make-up System, current SEP coolingsystem, and SEP Island are all classified as Quality Group D, Quality Class IlI-AQ(Augmented Quality).
- New SEP Island purification equipment is designed to remove soluble and insoluble foreign matter from the SEP water and dust from the pool surface.* Inadvertent draining of the SFP, including siphoning, below approximately 23 feet abovethe stored fuel is not adversely impacted by replacing the SFPCS with the ISFPCS. Anyleakage is detected as a result of reduction in pool inventory.
A sump with adequate Document Control Desk 10-capacity is provided to collect system leakage.
A high level alarm is provided toannunciate in the control room when a high sump level is reached.*The Fuel Handling Building including its missile barriers, the Spent Fuel Pool and Liner,and related Fuel Pool structural components remain safety-related Seismic Category I.* The existing Fuel Handling Building HVAC equipment has sufficient margin available toappropriately control the environment to within design limits with the introduction ofadditional heat loads from the ISFPCS equipment.
- The enhanced Spent Fuel Pool Makeup System will all be contained within a buildingproviding protection against tornados.
- The ISFPCS is designed, constructed and supported in conformance with California Building Code (CBC) requirements which require both seismic and wind-loading capability.
The ISFPCS primary cooling loop will be installed on the refueling floor in thenew fuel area, making it protected from tornados by the Fuel Building missile shields.Most equipment for the secondary loop will be installed outdoors between the Unit 2 and3 fuel handling buildings, with some inherent shelter against tornados as discussed inSection 2. Also, the recorded historical data suggests the low likelihood of a tornadooccurring at the SONGS site. The seismic design details are covered in Section 3.4below. A number of these details support response to potential tornado damage as wellincluding the fact that most equipment is modular with readily available replacements.
- The configuration of the ISFPCS cannot adversely impact the Seismic Category Iqualification of the current system. The new intake is completely separate.
Thedischarge shares diffuser hardware but the interconnection includes flexible hardware toavoid any transfer of loads between the two systems.
Should a failure occur in theSeismic Category Ill Island it can be isolated through manipulation of the valves used totransfer between systems.
- Further, should such failures lead to leakage in the primarysystem(s) the fluid will not be lost but would be spilled back onto the Spent Fuel Pooloperating deck(s) and return to the pool(s).
Should a failure occur in the Islandsecondary system, the failures be in the Island's secondary system there is nointeraction with the current system.3.2 Discussion 10OCFR50.82(a)(2) specifies that the 10 CFR 50 license no longer authorizes operation of thereactor or emplacement or retention of fuel in the reactor vessel after docketing the certifications for permanent cessation of operations and permanent removal of fuel from the reactor vessel.After the formal termination of reactor operations at SONGS the UFSAR Chapter 15 AccidentAnalyses were revised to eliminate those accidents no longer possible and to revise dosecalculations for those remaining.
The UFSAR was revised to reflect the new analysis and theChapter submitted initially as a separate submittal (Reference 6.10) and with the last revision tothe UFSAR (Reference 6.11). These analyses only credited the reduction in decay heat in thefirst 17 months of decay. The decay heat from the fuel in the pools currently has been furtherreduced since the fuel has been decaying for over 3 1/2/ years. Therefore, the accident analyses Document Control Desk 11-in the current revision of Chapter 15 are conservative with regard to decay heat levels andaccident consequences relative to the current state of the fuel.As part of its request for approval of the Permanently Defueled Emergency Plan, SCE used thefollowing metrics:
(1) demonstrating no Design Basis Accident could have radiological consequence which exceed EPA Protective Action Guidelines; and (2) >10 hours before storedfuel could reach a peak clad temperature of 900 °C in the limiting stored fuel assembly with nowater present in the pool and no air cooling.
SONGS demonstrated
>17 hours under adiabatic conditions (no heat losses of any kind) at the time the request was submitted (Reference 6.22).Further, SONGS demonstrated that with air-cooling (normal HVAC in service) the peak cladtemperature did not reach 565°C. The NRC reviewed a summary of the SONGS Units 2 and 3analyses and performed confirmatory calculations using the same conservative inputs. Basedon the provided analysis and the results of previous
- studies, the NRC staff concluded air coolingto be a credible method to maintain the fuel cladding temperature below that associated with theonset of cladding damage (Reference 6.5).The NRC staff's review addressed the adequacy of the then current and proposed Spent FuelPool cooling and make-up systems (References 6.6 and 6.7) as well as current and proposedMitigating Strategies for Beyond Design Basis Accidents associated with the Spent Fuel Pools.SCE supplied a summary of the current and future spent fuel pool cooling and make-upsystems, their quality and seismic classifications and related information in response toPermanently Defueled Emergency Plan (PDEP) RAI-16.Based in large part on these analyses and the current and proposed Spent Fuel Pool CoolingSystems, SFP Primary and Backup Makeup Systems, and Mitigating Strategies, the NRCgranted the requested relief regarding certain emergency planning requirements (Reference 6.5).SCE has revised its calculations to more completely assess the effects of the reduced need forspent fuel pool cooling due to reduced decay heat load. SCE has documented decay heatloads from June 30, 2013 through the end of 2016 as shown in the figure below. This newcalculation uses a more accurate representation of pool geometry to include all pools (SFP,Cask Storage Pool, and Fuel Transfer Pool). Using nominal conditions the heat-up to boilingwould take over a week and evaporation down to 3 feet above stored fuel would in addition takewell over a month (Reference 6.12). While the plant was operational, boiling could take place inless than two and one half hours requiring a much shorter plant response time to restorecooling.
With the current plant conditions it is reasonable to expect that any potential impact toSFP cooling could be resolved by operating staff well within the timeframe described above.NRC confirmed the time available to initiate mitigative actions consistent with current plantconditions as part of the granting exemptions listed in the PDEP.
Document Control Desk 12-4.OIsOI~40427 Feet @ 72"F (All Pools)..$SP itett Deay -4A-Tlmp i itc -ol1Tot~tlTime to ] nbove Tapt lf uet Anmbiie60II jioi*oo2 Sf +004O,°(tI102il[+06 m201*+6Jun-13Dac-l]Jun-14Dec-14Jun-ilDec-16DateSCE has had an independent assessment of dose results performed.
That assessment (Reference 6.14) confirmed that the projected doses reported in UFSAR Chapter 15 for the"Spent Fuel Pool Boiling" event remained bounding (and orders of magnitude below anyapplicable limits).
Those previous results and applicable limits as shown in UFSAR Table 15.7-8, are repeated here:Table 15.7-8RADIOLOGICAL CONSEQUENCES OF SPENT FUEL POOL BOILINGSFP BOILING ACCEPTANCE DOSE RECEPTOR DOSE CRITERION (REM TEDE) (REM TEDE)Control Room (30-day accident duration) 11 .96E-03(11.96 mRem TEDE)EAB (Maximum 2-hour dose -- 0.0 to 2.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />) 0.08E-03(0.08 mRem TEDE)6.LPZ (30-day accident duration) 0.25E-03(0.25 mRem TEDE)6.
Document Control Desk 13-3.3 Remaining Safety FunctionReview of Spent Fuel Pool CoolinqPer the 10 CFR 50.2 definition of safety-related, the spent fuel pool cooling system has beenreclassified to non-safety related because there are no UFSAR Chapter 15 accidents whichcould result in potential offsite exposures comparable to the applicable guideline exposures setforth in 10 CFR 50.34 (a)(1), 10 CFR 100.11 or 10 CFR 50.67 (Accident Source Term). Thusthe SFPCS and ISFPCS do not perform a safety-related function.
Because SONGS Units 2 and3 are undergoing decommissioning, the only remaining fission product barrier that requiresprotection is the spent fuel cladding of the stored fuel assemblies in the pools. Consequently, the only safety function(s) remaining relates to maintaining the structural integrity of the spentfuel pool and water level to allow for passive cooling of the fuel assemblies (active cooling fromthe SFP cooling system no longer provides a safety-related function as defined in the updatedChapter 15 Fuel Pool Boiling Accident
- Analysis, only maintaining water level -Reference 6.12).Thus, the only remaining safety related SSCs at SONGS are the Spent Fuel Pool and relatedstructural components (pool liner, structure, and racks).The Make-up System will ensure that sufficient water is supplied to the SFPs in the event of lossof cooling.
In addition to the Seismic Category I make-up source, there are currently numerousother sources of makeup for the SFPs, including:
- As provided in SONGS Units 2 and 3 procedures, the Nuclear Service Waterconnections located on the SEP operating level can be used via hoses to fill the pool.These connections are QC Ill, Seismic Category II.*As provided in SONGS Units 2 and 3 Mitigation Strategies, water from Fire Water TanksT-102 and T-103 via Fire Pumps P-220 (diesel driven),
P-221 or P-222 (both of whichare motor driven) can be provided through the installed fire system piping to 2 fire hosecabinets located on the Spent Fuel Pool Operating level. The tanks, pumps and pipingare QC llI-FPS and Seismic Category II.*As provided in SONGS Units 2 and 3 Mitigation Strategies, makeup to the SFPs can beprovided using water from one or more of the following sources:
Demineralized WaterTanks T-266, T-267 or T-268, all are located at a higher elevation at the MakeupDemineralizer Area at the south end of the plant. Skid mounted pump P-i1058 deliverswater from these sources to the seismic standpipe and from the standpipe to the SEP. T-266, T-267 and T-268 are QC Ill, Seismic Category I1. P-1058 is QC III-EPS and SeismicCategory Ill.* As discussed in SONGS Units 2 and 3 Mitigation Strategies, the 10" City Water LineSupply Line can be used as an alternate source of SEP makeup water.*Another makeup path is available using the Seismic Category I Demineralized WaterStorage Tank (T-351) located in the North Industrial Area along with Seismic Category Iportable diesel driven Fire Pump (P-i1065) using strategically staged hoses between thetank, pump, Seismic Category I standpipe and the Spent Fuel Pool. The hoses are Document Control Desk 14-pressure tested annually and are inspected for location quarterly per SONGS Units 2and 3 procedures.
The Mitigation Strategies are sequenced to assure the strategies can be deployed in 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> orless (Reference 6.23). The capability to achieve this time was evaluated in a formal study andfurther demonstrated in the field using actual staff, procedures and equipment.
Given the number and diversity of makeup sources, and the time available to supply makeup tothe SFPs in the loss of spent fuel pool cooling, it is not credible to postulate a complete loss ofmakeup to a SEP. The NRC's June 30, 2014 letter concerning San Onofre Nuclear Generating
- Station, Units 2 and 3 -Rescission of Order EA-12-049 (Reference 6.13), states in part:"[T]he time to boil off water inventory in the SFP to a level of 10 feet above the spent fuelwill be sufficiently long to obviate the need for additional strategies to restore SFPcooling.
The NRC staff concludes that given the low decay heat levels and the long timeto boll off, the reliance on the SFP inventory for passive cooling provides an equivalent level of protection as that which would be provided by the initial phase of the guidanceand strategies for maintaining or restoring SFP cooling capabilities that would benecessary for compliance with Order EA-12-049 using installed equipment.
The stafffurther concludes that the long time to boil off the SFP inventory to a point at whichmakeup would be necessary for radiation shielding purposes obviates the need for thetransition phase of the guidance and strategies that would be necessary for compliance with Order EA-12-049 using on-site portable equipment.
The staff also concludes thatthe low decay heat and long boll-off period provides sufficient time for the licensee toobtain off-site resources on an ad hoc basis to sustain the SFP cooling functionindefinitely, obviating the need for the final phase of the guidance and strategies thatwould be necessary for compliance with Order EA-12-049."
Similarly, as described in NRC's 2015 exemption from certain emergency planningrequirements for SONGS Units 2 and 3 (Reference 6.5):"Additionally, in its letters to the NRC dated October 6, 2014, and December 15, 2014,SCE described the SFP makeup strategies that could be used in the event of acatastrophic loss of SFP inventory.
The multiple strategies for providing makeup water tothe SEP include:
using existing plant systems for inventory makeup; an internal strategythat relies on installed fire water pumps and service water or fire water storage tanks; oran external strategy that uses portable pumps to initiate makeup flow into the SFPsthrough a seismic standpipe and standard fire hoses routed to the SFPs or to a spraynozzle. These strategies will continue to be required as a license condition.
Considering the very low probability of beyond-design-basis accidents affecting the SFP, thesediverse strategies provide defense-in-depth and time to provide additional makeup orspray water to the SEP before the onset of any postulated offsite radiological release."
It is not necessary to postulate both a loss of spent fuel pool cooling in conjunction with a loss ofspent fuel pool makeup. Concurrent failures are not postulated in UFSAR Section 15.7.3.8related to SEP boiling and are not credible given the number of diverse sources of makeup andthe time available to supply makeup. Further, loss of cooling is the initiating event mitigated byeither the fully installed make-up system or available mitigating strategies.
Document Control Desk 15-Spent fuel pool boiling, although
- unlikely, will not adversely affect the integrity of the SFPs. Thereinforced concrete temperature differences and gradients were determined based on an insideface temperature of 230°F (water temperature of 21 20F and gamma heating of 1 80F). Thatanalysis indicates that the SEP walls have sufficient structural capability to accommodate thisthermal loading.Review of Enhanced Spent Fuel Pool MakeupSCE intends to modify existing equipment to provide enhanced SEP makeup capability duringdecommissioning.
To ensure the SEP inventory makeup is maintained, the enhanced SEPMakeup design will include features for makeup function reliability including redundancy, redundant power sources, and system cross-tie capabilities, as discussed above.In response to various requirements, SCE has proceduralized the use of multiple and diversemeans to provide backup spent fuel pool makeup to support the function of maintaining levelwithin the pool. The robust design and construction of the spent fuel pool, multiple and diversemeans for makeup (less than two hours to implement makeup mitigation strategy with minimumstaffing),
and the available time for response measures should a challenge to the stored fueloccur provide adequate defense-in-depth measures to protect public health and safety.Review of Power SupplyAs discussed above, the bases for the original design requirements for electrical power to spentfuel pool and makeup systems are no longer necessary given the following:
- The spent fuel pool cooling no longer serves a safety-related function and the equipment is not safety-related,
- The remaining safety function is to protect spent fuel cladding by maintaining water levelin the pool,* Spent fuel pool heat loads are reduced and response times for mitigating actions haveincreased significantly, and* Potential radiation doses to the public are now well below current acceptance criteria.
Therefore, SCE processed and approved a design change and associated 50.59 reviewsthat found that the bases for licensing commitments described in the UFSAR for electrical SSCs no longer apply. This change allowed SONGS to reduce the quality assurance requirements of 10CER50 Appendix B related to maintenance,
- testing, procurement, etc.This change reclassified all safety related electrical SSCs from QC II (Class 1E) to non-safety related QO Ill (non-Class 1 E). Based on the change in safety class and the currentplant status of the spent fuel pool cooling and makeup systems (including diverse makeupsystems that do not depend on electrical power), SCE is proposing that the seismicrequirements for the power system be reduced as well. The new Power Ring that will supplyelectrical power to the remaining plant systems has been designed as Seismic Category Ill,as listed in this LAR for specific exception to Regulatory Guide 1.29 criteria.
Document Control Desk 16-Summary of Seismic Classification Impact on Regqulatory Guide 1.29The above discussion forms the basis for the seismic classifications of the ISFPCS andelectrical power systems.
Based on the current characteristics of spent fuel stored in the spentfuel pools, SCE has evaluated the decay heat loads and determined that it is not necessary forthe spent fuel pool cooling systems and associated power systems to meet Appendix B qualityassurance requirements or Seismic Category I requirements because the system does notperform a safety-related function.
Seismic design requirements ensure that SSCs can continue to perform their safety functionwithout the loss of capability after an earthquake.
For a site that has permanently ceasedoperations and removed fuel from the reactor vessel, safety is afforded by preventing andmitigating the consequences of accidents that could result in offsite exposures comparable tothe applicable guideline exposures set forth in 10 CFR 50.34 (a)(1), 10 CFR 100.11 or 10 CFR50.67 (AST). Analyses of postulated events at SONGS indicate that there are no accidents thatresult in sufficient offsite exposures at or above these limits. Also, the time required to mitigatea loss of spent fuel pool cooling and make-up is significantly increased given the reduced decayheat levels of the fuel.The SONGS Spent Fuel Pool and related structural components (pool liner, structure, andracks) provide for the integrity of the spent fuel pool, and thus, are Seismic Category I. Thespent fuel pool cooling systems, the associated support systems, and components to supplypower to support these systems are designed to meet Seismic Category Ill requirements 3.4 Seismic Category IlI Design DetailsAll new ISFPCS equipment anchorage, piping and support infrastructure have been designed tomeet the seismic requirements of the California Building Code (CBC), which is described inmore detail in the following paragraphs.
Additionally, a supply of replacement parts is readilyavailable to facilitate any needed repairs if the system were damaged in a major earthquake ortornado.The 2013 CBC requires that non-structural components (including architectural, mechanical, electrical and plumbing equipment) and their supports and attachments that are permanently attached to a structure be designed and constructed to resist the effects of earthquake motionsin accordance with design loads and other requirements contained in the American Society ofCivil Engineers Minimum Design Loads and Requirements for Buildings and other Structures (Reference 6.21). CBC Section 1613 and ASCE 7 lay out specific procedures for determining seismic design criteria for different site classes (determined by soil properties) andstructure/component risk categories based on probabilistic analysis of seismic loading (i.e.,ground acceleration) for a specific location.
The CBC mandates the use of USGS MaximumConsidered Earthquake Ground Motion Response Acceleration maps for seismic designanalysis.
The USGS also provides an on-line, georeferenced Risk Targeted Ground MotionCalculator for the purposes of calculating ground motion parameter values in accordance withASCE 7 standards for building and non-structural design.SCE has conducted seismic design analysis for the ISFPCS following the procedures andrequirements of ASCE 7, generating a set of horizontal and vertical ground-shaking intensities (spectral accelerations (SA)) defining the design seismic loads for the proposed system. Thedesign seismic response spectrum encompasses ground-shaking intensities of 0.820 g at a 0.2 Document Control Desk 17-second period (0.2 sec SA) and 0.471 g at a 1.0 second period (1.0 sec SA), corresponding to aPeak Ground Acceleration (PGA) of approximately 0.35 g -0.45 g. These ground-shaking intensities correspond to an average return period of approximately 1,500 -2,000 years. TheISFPCS, including mechanical, electrical, piping and support components, will be designed andinstalled to withstand this level of ground-shaking, without collapsing or resulting in damage toadjacent equipment.
In the unlikely event that the system was to fail, protection of the fuelcladding will be preserved through passive cooling through makeup.In summary, the ISFPCS will be designed and constructed in accordance with applicable state(the CBC) and national (ASCE 7) seismic standards and will be inspected and maintained toassure the reliability of system components.
Compliance with these standards will minimize theimpact of geologic hazards and assure structural stability that will support any necessary repairspost earthquake.
3.5 Schedule and Resource ImpactsSCE is requesting approval of this amendment within six months. This LAR was initiated following discussions with NRC subsequent to an on-site inspection of modifications and the 10CFR 50.59 process documentation.
The Post-Shutdown Decommissioning Activities Report (PSDAR),
Section II, provides anoverview of the planned decommissioning activities.
These activities include site modifications as necessary to support future decommissioning and decontamination efforts.
SCE plans toimplement a series of 'cold & dark' modifications to support future plant decommissioning work.To dismantle and dispose of the permanent plant equipment, temporary equipment must beprovided to support various ongoing functions as well as the associated electrical power andventilation needed to support decommissioning activities.
SONGS Units 2 and 3 'cold & dark'modifications include the SEP Island. Based on industry decommissioning experience, the useof independent non-plant systems for providing SEP cooling and make-up will reduce thepotential for decommissioning activities to inadvertently damage installed plant SEP-related components which could result in a loss of SEP cooling or pool inventory.
The primary reason for pursuing "cold and dark" conditions is to reduce current personnel safetyhazards (it also advances the schedule, which is a benefit to the Decommissioning Trust Fund).The personnel safety benefit is to allow the removal of power and other energy sources from asmuch of the plant as possible.
Operations,
- security, maintenance and radiation protection personnel come into contact with most parts of the plant on a daily basis. The equipment installed to replace current plant equipment for appropriate functions (like spent fuel poolcooling) can be located and labelled (conduits color-coded, etc.) to make them very readilyrecognized, making all personnel contact with equipment much safer. Everything else can beremoved (except for the existing Spent Fuel Pool Cooling System and its support systemspending NRC approval of this LAR). While intended interactions can be done safely either way;unintended ones have less potential safety risk since unmarked cables and piping will not beenergized or pressurized.
The Spent Fuel Pool Cooling System relies directly on the Component Cooling and Saltwater Cooling Systems to transfer heat from the pool inventory to the Ultimate Heat Sink (the Pacific).
These two systems alone are fairly extensive.
They, in turn, rely on a number of AC and DCelectrical
- sources, main busses and associated distribution.
They also require some HVAC,Compressed Air and other equipment.
- Finally, a number of the other seemingly unrelated
'cold Document Control Desk 18-and dark' modifications repurpose equipment or power sources such that their unavailability delays those modifications as well.Therefore, approval of this License Amendment is critical path to much of 'cold and dark' anddelays the removal from service of a number of systems that had been pending issuance of thePermanently Defueled Emergency Plan and Technical Specifications.
These delayssignificantly complicate the reduction in resources supporting such efforts which adversely impacts the Decommissioning Trust Fund.3.6 Precedents There have been several plants which have previously implemented a spent fuel pool coolingisland as part of decommissioning.
For the sake of brevity, the following focuses on threeexamples:
Zion, Maine Yankee, and Connecticut Yankee. All three plants downgraded theclassifications of their spent fuel pool cooling systems.
NRC was aware of the downgrade inclassification of the spent fuel pool cooling systems at Maine Yankee and Connecticut Yankee,since the licensee and NRC conducted public meetings on that topic as discussed below. In thecase of Maine Yankee and Zion, the licensee justified the lack of safety-related cooling andmakeup on the ground that there were numerous and diverse methods of makeup, that theradiological impacts of pool boiling were low, and that boil-off of the pool water would not occurfor many days allowing sufficient time to provide makeup.ZionThe 2000 Defueled Safety Analysis Report (DSAR) for Zion (Reference 6.15), Section 3.2.2indicates that the spent fuel pool is Seismic Category I. Section 3.9.4.4 discusses thevarious sources of makeup for the spent fuel pool, and concludes that "Sufficient time existsfrom the time cooling is lost and boiling occurs that compensatory measures can be taken,including supplying make-up water, to prevent fuel damage and off-site releases that exceedUSEPA Protective Action Guidelines or 10CFR100 limits."
Section 3.10.1 discusses thesecondary cooling loop which provides for air cooling through use of cooling towers, which isclassified as "important to the defueled condition."
In contrast, as indicated in Table 3-3, thespent fuel pool cooling loop pump, strainers, valves, and piping are Seismic Category I tothe extent they are in Seismic Category I structures or concrete.
Maine Yankee*As discussed in the 1998 DSAR for Maine Yankee(Reference 6.16), pages 3-11 and 3-13,the spent fuel pool was Seismic Category I. As discussed on page 3-12, Maine Yankeeused the 10 CFR 50.59 process to reclassify SSCs, and Section 3.1 .2.1 discusses in detailthe process that Maine Yankee used to reclassify certain SSCs from safety-related to"important to the defueled condition."
Section 3.3.1.3 contains a detailed evaluation of lossof cooling for the spent fuel pool, concluding on pages 3-74 and 3-75 that a loss of coolingwould not result in doses exceeding a small fraction of the limits in 10 CFR 100.11, that onlythe passive pool needs to be credited, and that there is ample time for operators to restorecooling or provide makeup prior to uncovering the spent fuel. In particular, the DSARemphasizes that sufficient makeup capacity exists through diverse sources, including thetown water supply and fire water pump, and that the active components of the cooling andmakeup system are not safety-related.
Section 5.5 evaluates several accidents involving Document Control Desk 19-loss of cooling, and again relies upon multiple and diverse sources of non-safety-related makeup.*As discussed in NRC's summary of a 1998 meeting (Reference 6.17), Maine Yankeediscussed the reclassification of the spent fuel pool cooling system and other SSCs. Page15 of the slides states that accidents would not have consequences comparable to the Part100 limits, and that SSCs with a fuel protection function that were previously classified assafety-related would be reclassified as "Important to the Defueled Condition."
MaineYankee also discussed in detail its plans for a spent fuel pool island, including severing tiesto the ultimate heat sink and existing off-site power supplies.
- The 2001 DSAR for Maine Yankee (Reference 6.18) is similar in approach to the 1998DSAR, but relies upon the spent fuel pool island rather than the normal spent fuel poolcooling system.Connecticut Yankee*As discussed in NRC's summary of a 1998 meeting (Reference 6.19), Connecticut Yankeediscussed reclassification of the spent fuel pool cooling system. Page 17 of the slides statesthat spent fuel pool island cooling system would be classified as non-safety-related andSeismic Category II (but that special QA requirements would be applied, which arediscussed in more in detail on Slide 23). In contrast, SSCs needed for the integrity of thespent fuel pool would be safety-related and Seismic Category I. Slide 22 indicates thatthere would be 26 days for the pool water to evaporate within 8 feet of the racks (therewould be no boiling absent forced cooling).
- Connecticut Yankee's 1999 Summary of Changes per 10 CFR 50.59, Evaluation SY-EV 0102 (Reference 6.20), discusses the reclassification of the spent fuel pool cooling systemand electrical distribution system from safety-related to non-safety-related (the emergency makeup system remained safety-related).
The evaluation concluded that the change onlyaffects testing, inspection, modification and maintenance of SSCs that are not required forthe safe storage of spent fuel or storage of emergency makeup water to the Spent FuelPool, and that loss of Spent Fuel Pool Cooling forced flow is not an accident initiating event.Additionally, in the decommissioned state, the function which is required for safe storage ofspent fuel is to keep the fuel covered with sufficient water for cooling and shielding, and thatall equipment that prevents the escape of water from the Spent Fuel Pool are classified andwill be maintained as QA Category I and seismic.In summary, it appears that Zion, Maine Yankee, and Connecticut Yankee all took very similarapproaches to SONGS Units 2 and 3, in that each used a spent fuel pool island, each continued to classify the spent fuel pool as Seismic Category I, and each reclassified all or portions of thespent fuel pool cooling system as non-safety-related (but with augmented quality).
Document Control Desk 20-4.0 REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria Pursuant to RIS 00-017: Managing Regulatory Commitments Made by Power ReactorLicensees to the NRC Staff, and NEI 99-04 "Guideline for Managing NRC Commitment Changes,"
SCE is requesting commitment changes to Regulatory Guides in the UFSAR. Inparticular, reclassifying the seismic classification of spent fuel cooling, reclassifying the seismicclassification of electrical power system for both the spent fuel cooling and makeup systems,and potentially causing the spent fuel cooling and electrical power system to be subject toimpact from tornado missiles, was determined to be a change in Regulatory Guide 1.13, 1.29,and 1 .76 commitments.
The proposed changes in commitments to Regulatory Guide 1.13, 1.29, and 1.76 are consistent with NRC regulations.
Specifically:
The change from a Seismic Category I spent fuel pool cooling system to a Seismic CategoryIll ISFPCS without full tornado protection is consistent with General Design Criterion (GDC)2 in Appendix A to 10 CFR Part 50 and Appendix A to 10 CFR Part 100. GDC 2 requiresthat SSCs important to safety be designed to withstand the effects of natural phenomena such as earthquakes and tornadoes.
Appendix A to Part 100 provides more details forcompliance with GDC 2. It states that SSCs shall be designed to remain functional in theevent of a safe shutdown earthquake (i.e., Seismic Category) if they are necessary toassure: (1) the integrity of the reactor coolant pressure
- boundary, (2) the capability to shutdown the reactor and maintain it in a safe shutdown condition, or (3) the capability toprevent or mitigate the consequences of accidents which could result in potential offsiteexposures comparable to the guideline exposures in 10 CFR 100.11. Because the ISFPCSis not part of the reactor coolant pressure boundary and does not relate to safe shutdown ofthe reactor, and because failure of ISFPCS would not result in exposures comparable tothose in 10 CFR 100.11, it does not need to be designed to be Seismic Category I orwithstand design basis tornados.
- The change from a Seismic Category I electrical power system for power to the spent fuelpool cooling system and make-up system to a Seismic Category IlI electrical power systemis consistent with GDC 2 and Appendix A to Part 100. As a support system for the ISFPCS,the electrical power system does not need to have any greater seismic classification thanthe ISFPCS. Furthermore, given the large number of make-up systems and the largeamount of time available to provide make-up, it is not credible to postulate a complete lossof make-up and uncovering of the spent fuel even in the event of a safe shutdownearthquake.
Therefore, the electrical power system does not need to be Seismic Category I.4.2 No Significant Hazards Consideration The proposed changes identify exceptions to Regulatory Guides 1.13, 1.29, and 1.76 to reflectthe permanently defueled condition.
Specifically, the proposed changes permit the Independent Spent Fuel Pool Cooling Systems (ISFPCS) to be approved as the remaining operational QAClass IIl-AQ and Seismic Category Ill spent fuel cooling system, and to retire the current coolingsystem from operation.
In addition, the proposed changes define the Spent Fuel Pool Make-up Document Control Desk 21-System to be QA Class III-AQ and Seismic Category I, and associated electrical modifications for installation of a non 1 E, non-seismic power supply to these systems.Southern California Edison (SCE) has evaluated whether or not a significant hazardsconsideration is involved with the proposed amendment by focusing on the three standards setforth in 10 CFR 50.92, "Issuance of Amendment,"
as discussed below:1. Do the proposed changes involve a significant increase in the probability orconsequences of an accident previously evaluated?
The only accident previously evaluated, is the Spent Fuel Pool Boiling Event. The initiating event (loss of cooling) would no longer lead to a rapid increase in pool temperature to theboiling point or to a relatively short-term reduction in pool level due to evaporative losses.Currently a loss of cooling would lead to a very slow heat-up toward the boiling point takingat least a week or more. From that point the slower evaporative losses would take severalweeks to reduce inventory to unacceptable levels.The most likely cause of a loss of function of the Spent Fuel Pool Cooling System (SFPCS)is not a failure of components in the cooling system, but instead a loss of electrical power.The probability of a loss of power is substantially higher than the probability of acontemporaneous common cause failure of active components in the cooling system. Forexample, NRC has collected operating experience on loss of Spent Fuel Pool (SFP) coolingfor nuclear plants in the U.S., which includes both safety-related and non-safety-related SFPcooling systems.
As indicated in NUREG-1 275, Volume 12, the causes of loss of SFPcooling were the loss of the SFP cooling pumps due to loss of electrical power (39 of 56events),
loss of suction from the spent fuel pool, flow blockage, loss of the heat sink, andone case of inadequate configuration control.
As concluded by the NRC: "The dominantcause of the actual loss of SFP cooling events was loss of electrical power to the SFPcooling pumps." There were no cases involving a common cause failure mode, such asseismic events or tornados.
Given this operating experience, any increase in the probability of a spent fuel pool boiling event due to the seismic reclassification of the system would beminimal in comparison to the failure rate due to loss of electrical power.The change in commitment does not affect the consequences of the spent fuel pool boilingaccident (which by definition assumes loss of the spent fuel pool cooling system).
Reviseddose calculations were completed to support the changes to the Updated Final SafetyAnalysis Report (UFSAR) Chapter 15 Accident
- Analysis, and the UFSAR was revised toreflect the new analysis.
These were recently reviewed to verify they remain bounding forthe much slower event even if it is not terminated (through restored cooling or adequatemake-up) prior to reaching levels approaching the top of the stored fuel. This reevaluation confirmed the doses previously calculated remain bounding and several orders ofmagnitude below applicable limits.Therefore, the proposed changes do not involve a significant increase in the probability orconsequences of an accident previously evaluated.
Document Control Desk 22-2. Do the proposed changes create the possibility of a new or different kind of accidentfrom any accident previously evaluated?
The only accident relevant to this proposed change would be an unmitigated Spent FuelPool Boiling Event (i.e., boiling without restoration of cooling or makeup prior to uncovering of the spent fuel). The initiating event (loss of cooling) would no longer lead to a rapidincrease in pool temperature to the boiling point and a relatively short-term reduction in poollevel due to evaporative losses. Currently a loss of cooling would lead to a very slow heat-up toward the boiling point taking at least a week or more. From that point the slowerevaporative losses would take several weeks to reduce inventory to unacceptable levels.The only safety function remaining relates to maintaining the fuel cladding in the SEP(cooling is not a safety-related function as defined in the updated Chapter 15 Fuel PoolBoiling Accident
- Analysis, only maintaining water level -Reference 6.12). The onlyremaining safety related SSCs at SONGS Units 2 and 3 are the Spent Fuel Pool and relatedstructural components (pool liner, structure, and racks).The Make-up System will ensure that sufficient water is supplied to the SFPs in the event ofloss of cooling.
In addition to the Seismic Category I make-up source, currently there arenumerous other diverse sources of makeup for the SFPs, including:
- As provided in SONGS Units 2 and 3 procedures, the Nuclear Service Waterconnections located on the SEP operating level can be used via hoses to fill the pool.These connections are QC III, Seismic Category II.*As provided in SONGS Units 2 and 3 Mitigation Strategies, water from Fire Water TanksT-102 and T-103 via Fire Pumps P-220 (diesel driven),
P-221 or P-222 (both of whichare motor driven) can be provided through the installed fire system piping to 2 fire hosecabinets located on the Spent Fuel Pool Operating level. The tanks, pumps and pipingare QC III-EPS and Seismic Category II.*As provided in SONGS Units 2 and 3 Mitigation Strategies, makeup to the SFPs can beprovided using water from one or more of the following sources:
Demineralized WaterTanks T-266, T-267 or T-268, all are located at a higher elevation at the MakeupDemineralizer Area at the south end of the plant. Skid mounted pump P-i1058 deliverswater from these sources to the seismic standpipe and from the standpipe to the SEP. T-266, T-267 and T-268 are QC III, Seismic Category II. P-1058 is QC Ill-EPS and SeismicCategory Ill.* As discussed in SONGS Units 2 and 3 Mitigation Strategies, the 10" City Water LineSupply Line can be used as an alternate source of SEP makeup water.*Another makeup path is available using the Seismic Category I Demineralized WaterStorage Tank (T-351) located in the North Industrial Area along with Seismic Category Iportable diesel driven Fire Pump (P-i1065) using strategically staged hoses between thetank, pump, Seismic Category I standpipe and the Spent Fuel Pool. The hoses arepressure tested annually and are inspected for location quarterly per SONGS Units 2and 3 procedures.
The Mitigation Strategies are sequenced to assure the strategies can be deployed in 2hours or less. The capability to achieve this time requirement was evaluated in a formalstudy and further demonstrated in the field using actual staff, procedures and equipment.
Document Control Desk 23-Given the number and diversity of makeup sources, and the time available to supplymakeup to the SFPs in the loss of spent fuel pool cooling, it is not credible to postulate acomplete loss of makeup to a SEP. As discussed in NRC's June 30, 2014 letter concerning San Onofre Nuclear Generating
- Station, Units 2 and 3 -Rescission of Order EA-12-049:
"[T~he time to boll off water inventory in the SFP to a level of 10 feet above the spent fuelwill be sufficiently long to obviate the need for additional strategies to restore SEPcooling.
The NRC staff concludes that given the low decay heat levels and the long timeto boll off, the reliance on the SFP inventory for passive cooling provides an equivalent level of protection as that which would be provided by the initial phase of the guidanceand strategies for maintaining or restoring SFP cooling capabilities that would benecessary for compliance with Order EA-12-049 using installed equipment.
The stafffurther concludes that the long time to boll off the SEP inventory to a point at whichmakeup would be necessary for radiation shielding purposes obviates the need for thetransition phase of the guidance and strategies that would be necessary for compliance with Order EA-12-049 using on-site portable equipment.
The staff also concludes thatthe low decay heat and long boll-off period provides sufficient time for the licensee toobtain off-site resources on an ad hoc basis to sustain the SEP cooling functionindefinitely, obviating the need for the final phase of the guidance and strategies thatwould be necessary for compliance with Order EA-12-04 9."Similarly, as described in NRC's 2015 exemption from certain emergency planningrequirements for SONGS Units 2 and 3:"Additionally, in its letters to the NRC dated October 6, 2014, and December 15, 2014,SCE described the SEP makeup strategies that could be used in the event of acatastrophic loss of SEP inventory.
The multiple strategies for providing makeup water tothe SEP include:
using existing plant systems for inventory makeup; an internal strategythat relies on installed fire water pumps and service water or fire water storage tanks; oran external strategy that uses portable pumps to initiate makeup flow into the SFPsthrough a seismic standpipe and standard fire hoses routed to the SFPs or to a spraynozzle. These strategies will continue to be required as a license condition.
Considering the very low probability of beyond-design-basis accidents affecting the SFP, thesediverse strategies provide defense-in-depth and time to provide additional makeup orspray water to the SEP before the onset of any postulated offsite radiological release."
It is not necessary to postulate both a loss of spent fuel pool cooling in conjunction with aloss of spent fuel pool makeup, and such an event is not postulated in UFSAR Section15.7.3.8 related to SEP boiling and is not credible given the number of diverse sources ofmakeup and the time available to supply makeup.As currently discussed in UFSAR 9.1.2.3, spent fuel pool boiling also will not adversely affect the integrity of the SEPs. The reinforced concrete temperature differences andgradients were determined based on an inside face temperature of 230°F (watertemperature of 21 2°F and gamma heating of 1 8°F). That analysis indicates that the SEPwalls have sufficient structural capability to accommodate this thermal loading.Therefore, the proposed changes do not create the possibility of a new or different kind ofaccident from any previously evaluated.
Document Control Desk 24-3. Do the proposed changes involve a significant reduction in a margin of safety?The proposed changes do not alter any design basis or safety limits for the plant. Theapplicable limits are spent fuel clad temperature and spent fuel pool level. The spent fuelcladding temperature is assured by maintaining water level to support natural circulation cooling within the spent fuel racks. Forced cooling keeps evaporative losses and FuelHandling Building environs within nominal limits. Thus, the SSCs that support the designand safety limits are limited to those that maintain inventory (Spent Fuel Pool and relatedstructural components (pool liner, structure, and racks) and sufficient equipment to replaceevaporative or other losses. Complete loss of make-up in not credible given the existence of numerous sources of makeup and the time available to provide makeup. No changes tothe pool and its structures are proposed and make-up capability remains assured.Therefore, the proposed changes do not involve a significant reduction in a margin of safety.Based on the above, SCE concludes that the proposed changes present no significant hazardsconsideration, and, accordingly, a finding of "no significant hazards consideration" is justified.
4.3 Conclusions
In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposedmanner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and securityor to the health and safety of the public.5.0 ENVIRONMENTAL CONSIDERATION The proposed changes meet the eligibility criterion for categorical exclusion set forth in 10 CFR51 .22(c)(9),
because the proposed exemption involves:
(i) no significant hazards consideration; (ii) no significant change in the types or significant increase in the amounts of any effluent thatmay be released offsite; and (iii) no significant increase in individual or cumulative occupational radiation exposure.
Therefore, pursuant to 10 CFR 51.22(b),
no environmental impact statement or environmental assessment need be prepared in connection with the proposed changes.
Document Control Desk 25-
6.0 REFERENCES
6.1. Letter from M. Peter T. Dietrich (SCE) to Document Control Desk (USNRC),
dated June12, 2013, Certification of Permanent Cessation of Power Operations, San OnofreNuclear Generating
- Station, Units 2 and 3 (ML1 31640201
)6.2. Letter from Mr. Peter T. Dietrich (SCE) to Document Control Desk (USNRC),
dated June28, 2013, Permanent Removal of Fuel from the Reactor Vessel, San Onofre NuclearGenerating
- Station, Unit 3 (ML13183A391) 6.3. Letter from Mr. Peter T. Dietrich (SCE to Document Control Desk (USNRC),
dated July22, 2013, Permanent Removal of Fuel from the Reactor Vessel, San Onofre NuclearGenerating
- Station, Unit 2 (ML13204A304) 6.4. Letter from Thomas J. Wengert (NRC) to Thomas J. Palmisano (SCE), July 17, 2015:
Subject:
San Onofre Nuclear Generating
- Station, Units 2 and 3 -Issuance ofAmendment for Permanently Shutdown and Defueled Operating License and Technical Specifications.
6.5. Letter from Thomas J. Wengert (NRC) to Thomas J. Palmisano (SCE), June 4, 2015:
Subject:
San Onofre Nuclear Generating
- Station, Units 1, 2 and 3 and Independent Spent Fuel Storage Installation
-Exemptions from Emergency Planning Requirements and Related Safety Evaluation.
6.6. E-mail from T. J. Wengert (NRC) to A. L Sterdis (SCE) dated October 2, 2014;
Subject:
Draft Request for Additional Information (RAI-16)
Re: Emergency Planning Exemption Request (TAC NOS 3835, 3836 and 3837), ADAMS Accession No. ML 14286A025.
6.7. Thomas J. Palmisano (SCE) to the U. S. Nuclear Regulatory Commission (NRC) datedNovember 3, 2014;
Subject:
Response to Request for Additional Information Number 16Regarding Emergency Planning Exemption Request 10 CFR 50.12 San Onofre NuclearGenerating
- Station, Units 1, 2, 3 and ISFSI.6.8. Letter from Thomas J. Palmisano (SCE) to the U. S. Nuclear Regulatory Commission (NRC) dated March 21, 2014;
Subject:
Permanently Defueled Technical Specifications San Onofre Nuclear Generating
- Station, Units 2 and 3.6.9. NUREG/CR-6451, "A Safety and Regulatory Assessment of Generic BWR and PWRPermanently Shut down Nuclear Power Plants,"
issued in August 1997.6.10. Thomas J. Palmisano (SCE) to the U. S. Nuclear Regulatory Commission (NRC) datedSeptember 17, 2014;
Subject:
Updated Final Safety Analysis Report Chapter 15, SanOnofre Nuclear Generating
- Station, Units 2 and 36.11. Letter from Thomas J. Palmisano (SCE) to the U. S. Nuclear Regulatory Commission (NRC) dated February 11, 2015;
Subject:
Updated Final Safety Analysis Report SanOnofre Nuclear Generating
- Station, Units 2 and 36.12. SONGS Calc. No. N-0220-037, Spent Fuel Pool Time to Boil, including Appendix B -AllPools Time to Boil.6.13. Letter from Eric J. Leeds (NRC) to Thomas J. Palmisano (SCE), June 30, 2014:
Subject:
San Onofre Nuclear Generating
- Station, Units 2 and 3 -Rescission of Order EA-12-049, "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond Design Basis External Events" Document Control Desk 26-6.14. Anatech Corporation Report Number 1500960.401, Evaluation of Spent Fuel PoolBoiling Accident Dependence on Spent Fuel Pool Water Level, July 2015.6.15. Letter from R. M Krich (Commonwealth Edison Company) to the U. S. NuclearRegulatory Commission (NRC) dated October 30, 2000;
Subject:
Zion Nuclear PowerStation, Units 1 and 2, Submittal of Defueled Safety Analysis Report Update.6.16. Letter from Maine Yankee Atomic Power Company to the U. S. Nuclear Regulatory Commission (NRC) dated February 4, 1998;
Subject:
Maine Yankee Nuclear PowerStation, Submittal of Defueled Safety Analysis Report.6.17. Letter from Ronald R Bellamy (NRC) to Michael B. Sellman (Maine Yankee AtomicPower Company),
February 20, 1998:
Subject:
Meeting Summary-Maine YankeeAtomic Power Company, Meeting No. 98-02, JANUARY 28, 1998.6.18. Letter from Thomas L. Williamson (Maine Yankee Atomic Power Company) to the U. S.Nuclear Regulatory Commission (NRC) dated July 18, 2001;
Subject:
Submittal of theMaine Yankee Defueled Safety Analysis Report Rev. 18.6.19. Letter from Ronald R Bellamy (NRC) to R. A. Mellor (Connecticut Yankee Atomic PowerCompany),
April 16, 1998:
Subject:
Meeting Summary-Connecticut Yankee AtomicPower Company, Meeting No. 98-14, MARCH 11, 1998.6.20. Letter from R. A. Mellor (Connecticut Yankee Atomic Power Company) to the U. S.Nuclear Regulatory Commission (NRC) dated February 26, 1999;
Subject:
Submittal ofthe Haddam Neck Plant 10CFR50.59 Annual Report6.21. American Society of Civil Engineers ASCE 7-10 -Minimum Design Loads andRequirements for Buildings and other Structures, 2013 Edition, January 1, 2013.6.22. Letter from Thomas J. Palmisano (SCE) to the U. S. Nuclear Regulatory Commission (NRC) dated March 31, 2014;
Subject:
Amendment Application Numbers 223, 267, and252, Permanently Defueled Emergency Plan, San Onofre Nuclear Generating Station,Units 1, 2, and 3, respectively, and Independent Spent Fuel Storage Installation.
6.23. SONGS ERO Onshift Staffing Analysis for Mitigating Strategies for Catastrophic Loss ofSpent Fuel Pool Water Inventory, October 1, 2014.
Document Control DeskAttachment ASpent Fuel Pool 'Island' Description Backqround Due to the significant reduction in Spent Fuel Pool (SFP) heat load since final plant shutdownand the reduction in potential boundary dose consequences for the few remaining credibleevents, the SEP cooling functional requirements are reduced.
Based on industrydecommissioning experience, the use of independent non-plant systems for providing SEPcooling will reduce the potential for decommissioning activities to inadvertently damageinstalled plant SEP-related components which could result in a loss of SEP cooling or poolinventory.
San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 will design andinstall an independent SEP cooling and purification system. This SEP cooling and purification system is referred to as the SEP Island. To safely maintain SEP cooling, the SEP Islanddesign includes features that support cooling function reliability including component redundancy, redundant power sources, and system cross-tie capabilities.
Current SEPCSEach unit of the current Spent Euel Pool Cooling System (SEP05) consists of two loops, theSpent Fuel Pool (SEP) cooling loop and the purification lo0P. The SEPCS is normallycontrolled manually from the main control panel. Main Control Room alarms for high SEPtemperature, high and low SEP level, low SEP pump discharge pressure and, high radiation in the SEP area, are provided to alert the operator to abnormal circumstances.
A local alarmfor low SEP level is also provided.
The SFPCS consists of two 100% capacity SEP pumps and two 100% capacity SEP heatexchangers.
The SEP pumps are connected to a common suction header and a commonreturn header. The SFPCS also includes appropriate valves, piping, and instrumentation.
SEP water is circulated by the SEP pumps through the SEP heat exchangers where it iscooled. The heat is rejected to the Component Cooling Water (CCW) System, which, inturn, rejects heat to the Salt Water Cooling system and ultimately to the Pacific Ocean.Neither the CCW nor SWC systems are otherwise impacted by this modification.
TheSEP05 includes a purification loop that has been administratively removed from service andthe resin removed.The Independent Spent Fuel Pool Cooling System (ISEPCS) will be installed, tested andprovide run-in time prior to removing the current system from operation.
Thus, the ISEPCS willbe operating and the current Spent Fuel Pool Cooling System will be maintained as a fully-functional back-up.SEP Island System OverviewISEPCS is shown in the attached schematic.
The design will include one primary loop perSEP. Each primary loop includes two 100% capacity pumps and a single heat exchanger.
Replacement heat exchangers are readily available.
There will be one secondary loop perSEP. The secondary loop is a closed system that uses air cooled chillers to cool the secondary side water. Each secondary loop will consist of two 100% capacity pumps. To provideincreased reliability, the chiller units on the secondary loops include excess capacity with the Document Control Deskability to cross-tie between each SFP's secondary loops. All equipment for the secondary loop(which includes two chillers, a surge tank, two secondary pumps, electrical distribution panel,piping, valves, electrical wiring, conduit and instrumentation) is new, and except for someconduit, wiring and the small portion of piping to and from the primary heat exchanger, will beinstalled outdoors between the Unit 2 and 3 fuel handling buildings.
Piping installation andinspections will be performed per ANSI B3.1-2007.
The ISFPCS primary cooling loop will be installed on the refueling floor in the new fuel area.The ISFPCS primary loop takes suction from the upender pit area of the SFP, pumps thewarm water through a stainless steel, plate and frame, heat exchanger for cooling and thenreturns it to the SFP through the existing sparger.
The ISFPCS suction has been locatedseparate from that of the SFPCS to facilitate construction and testing without impacting SFPCS operation.
The SFP Island will be all new equipment and is independent of the SFPCS except for thesmall portion of the suction piping from the upender area of the SEP to the primary pump anda portion of the primary discharge piping from the heat exchanger to the sparger connection.
The new equipment will be installed inside the existing New Fuel Room. The primary pumpswill add to the heat loading in the room. However, the existing HVAC equipment hassufficient margin available to appropriately control the environment to within its designtemperature.
To support fuel movement during future pool-to-pad campaigns or otherwise the ISFPCSincludes a side-stream purification loop including a new ion exchanger for purification.
SFP Island Redundancy The SFP Island includes two 100% capacity primary loop pumps. One heat exchanger isavailable, with a replacement heat exchanger readily available for installation in eitherSEP. The secondary loop provides two 100% capacity pumps and two chillers withexcess capacity.
Cross-tie capability is provided such that two chillers provide sufficient capability for both SFPs.SEP Island Electrical PowerThe SFP Island primary and secondary pumps, chillers, and other components willinitially be powered from the existing plant electrical distribution system that have EDGbackup power.Separately from the ISFPCS, Southern California Edison (SCE) is planning to install anon-safety Seismic Category Ill Decommissioning Power Ring System to facilitate decommissioning of various plant systems.
This ring will be powered from offsitesources with a manual backup diesel generator.
The Decommissioning Power RingSystem will also power the ISFPCS. The transition to powering the ISFPCS from theDecommissioning Power Ring System will not occur until a manual diesel back-up isavailable.
Document Control DeskSFP island Seismic DesignThe SEP Island is designed to be non safety-related and Seismic Category Ill. The SEPIsland will be designed and installed such that the potential failure of any of itscomponents (e.g. a suction or return piping) during a seismic event will not damagesafety-related SSCs (e.g., the spent fuel storage racks) nor have an effect on the SEPwater inventory resulting in uncovering of the spent fuel.SEP Island Quality ClassThe SEP Island is designed to meet the same Quality Group and Quality Class as theexisting configuration.
The SEP Island will be Quality Group D and Quality Class llI-AQ.System CapacityThe SEPCS primary heat exchangers are capable of removing 31 M-BTU/hr.
They weresized based on decay heat loads associated with an operating plant and therefore are far inexcess needed currently for SONGS Units 2 and 3.The new ISFPCS primary heat exchanger is capable of removing 3.0 M-BTU/hr.
It was sized based on current heat loads as reported in Table 9.1-lB of the UFSAR. Thecurrent heat load from all stored fuel and one dry storage container is conservatively projected to be approximately 2.6 M- BTU/hr for the limiting pool (SONGS Unit 2) and willcontinue to decrease over time as the fission products decay further.Instrumentation and ControlsThe current SFPCS provides Main Control Room alarms for high SEP temperature, high andlow SEP level, low SEP pump discharge pressure and high radiation in the SEP area to alertthe operator to abnormal circumstances.
Additional level indication is available locally and inthe Main Control Room/Command Center.Control for the primary and secondary loops of the ISFPCS is provided via the programmable logic controllers (PLCs) and local manual operation.
Indications for primary loop processpressure, temperature and flow, ion exchanger flow, and SEP level will be provided in theMain Control Room/Command Center. The cooling water supplied by the chiller system ismaintained at least 5 psid above the primary side pressure in the heat exchanger.
If thedifferential pressure falls below 5 psid the primary pump is automatically shutdown to preventmigration of radioactivity from the primary to secondary side of the ISEPCS in the event of aleak in the heat exchanger.
This trip also prevents the dilution of the SEP boronconcentration by unborated water from the secondary side. If the temperature in thesecondary side exceeds 100°F, the secondary pump shuts off. All other ISFPCS controlfunctions are performed manually and locally.SEP Make-upDue to the significant reduction in SEP heat load since the final plant shutdown, and thereduction in potential boundary dose consequences in the few remaining credible events, the Document Control DeskSFP makeup functional requirements are reduced.
Based on industry decommissioning experience, the use of independent systems for providing SFP cooling and inventory makeup,will reduce the potential for decommissioning activities to inadvertently damage installed plantSEP-related components which could result in a loss of SFP cooling or pool inventory.
SCEwill modify existing equipment to provide independent SFP makeup capability duringdecommissioning.
To ensure the SEP inventory makeup is maintained, the SEP EnhancedInventory Makeup design will include features that enhance makeup function reliability including redundancy, redundant power sources, and system cross-tie capabilities.
TheSONGS Units 2 and 3 permanent SEP Enhanced Inventory Makeup system will beseismically-qualified, and also has proceduralized the use of multiple and diverse means toprovide backup spent fuel pool makeup to support the function of maintaining level within thepool. The robust design and construction of the spent fuel pool, multiple and diverse meansfor makeup, and the available time for response measures should a challenge to the storedfuel occur provides adequate defense-in-depth to protect public health and safety allowing theSEP Make-up system to be classified as Quality Group D, important to safety.The SEP Makeup system proposed for the SEP island is shown in the attached schematic.
The seismically qualified permanent SEP Enhanced Inventory Makeup system relies on apermanently installed Demineralized Water Storage Tank (DWST) located in the NorthIndustrial Area, with a combination of re-purposed and permanently installed new seismicqualified electric pumps and piping. This tank (previously for Unit 1) was designed andconstructed to ASME Rules and has a capacity of 150,000 gallons.
The backup mitigation makeup includes a dedicated 2500 gpm Diesel driven Pump, on wheels that is located directlyadjacent to the tank and positioned for use. The diesel driven pump equipment waspurchased with seismic qualification.
The mitigation system also includes hose connects fromthe fire pump to a Seismic Category I Eire Riser via a connection accessible through a door onthe plant east road at grade (el. 30 ft). Another hose from a Eire Riser connection locatedadjacent to the door into the Euel Pool Operating Deck (at elevation 60 ft.) directs the waterinto the Spent Euel Pool. The hoses between the Tank and Pumper and Pumper and Riserare safely stored to preclude any damage during a seismic event. These hoses are routinely inspected and tested, procedures are in place for setup and use, and dry runs have beenconducted showing installation of the backup mitigation makeup system can be done in lessthan 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. All components are either installed or safely stored for use with minimal manualaction. The previous Unit 2/3 Makeup Source, the Refueling Water Storage Tank (RWST)also required manual actions to align the system. The manual action for the previous SONGSUnits 2 and 3 RWST could be accomplished in approximately one half hour when boiling couldoccur within two and one half hours, and the manual action for the current Unit 1 DWST is lessthan two hours when boiling could occur after one hundred hours.In addition to the Seismic Category I make-up source, currently there are numerous othersources of makeup for the SEPs, including:
- As provided in SONGS Units 2 and 3 procedures, the Nuclear Service Waterconnections located on the SEP operating level can be used via hoses to fill the pool.These connections are QC Ill, Seismic Category II.* As provided in SONGS Units 2 and 3 Mitigation Strategies, water from Eire WaterTanks T-102 and T-103 via Eire Pumps P-220 (diesel driven),
P-221 or P-222 (both ofwhich are motor driven) can be provided through the installed fire system piping to 2 Document Control Deskfire hose cabinets located on the Spent Fuel Pool Operating level. The tanks, pumpsand piping are QC Ill-EPS and Seismic Category II.As provided in SONGS Units 2 and 3 Mitigation Strategies, makeup to the SFPs canbe provided using water from one or more of the following sources:
Demineralized Water Tanks T-266, T-267 or T-268, all are located at a higher elevation at the MakeupDemineralizer Area at the south end of the plant. Skid mounted pump P-i1058 deliverswater from these sources to the seismic standpipe and from the standpipe to the SEP.T-266, T-267 and T-268 are QC Ill, Seismic Category I1. P-1058 is QO IlI-FPS andSeismic Category Ill.* As discussed in SONGS Units 2 and 3 Mitigation Strategies, the 10" City Water LineSupply Line can be used as an alternate source of SEP makeup water.*Another makeup path is available using the Seismic Category I Demineralized WaterStorage Tank (T-351) located in the North Industrial Area along with Seismic CategoryI portable diesel driven Fire Pump (P-i1065) using strategically staged hoses betweenthe tank, pump, Seismic Category I standpipe and the Spent Fuel Pool. The hoses arepressure tested annually and are inspected for location quarterly per SONGS Units 2and 3 procedures.
The Mitigation Strategies are sequenced to assure the strategies can be deployed in 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />sor less. The capability to achieve this time requirement was evaluated in a formal study andfurther demonstrated in the field using actual staff, procedures and equipment.
Operation Once the LAR is approved, a turnover to Operations of ISFPCS is acceptable.
The SFPCSwill remain functional until the complete scope of the modification has been turned over toOperations and both systems may continue to be available for several weeks depending onsystem performance and other plant conditions.
Document Control DeskSFP PROPOSED SPENT FUEL POOL COOLING AND INVENTORY MALKEUP(DECOMMISSIONING)
Document Control Desk -.1-B.1-Attachment BProposed Exceptions toSONGS Units 2 and 3 Updated Final Safety Analysis ReportAppend ix 3A Mark-up Document Control Desk-B2San Onofre 2&3 FSARUpdatedAPPENDIX 3ACOMPARISON OF DESIGN WITH NRC REGULATORY GUIDES3A.1.13 REGULATORY GUIDE 1.13, SPENT FUEL STORAGE FACILITY DESIGNBASIS (REVISION 1, DECEMBER 1975)The San Onofre Units 2 and 3 design is consistent with recommendations of Regulatory Guide1.13. The subject of this Regulatory Guide is discussed in sections 3.5 and 3.8, and insubsections 9.1.2, 9.1.3, 9.4.2, 15.7.3.4, and 15.10.7.3.4, except for the following:
3A.1.13.1 Paraqraph C.8 of the Regulatory GuideThe Enhanced Spent Fuel Pool Make-up System is designed to Quality Group IlI-AQ andSeismic Category I. The Enhanced Spent Fuel Pool Make-up System will be powered by aSeismic Category Ill Decommissioning Power Ring System.3A.1 .26 REGULATORY GUIDE 1.26, QUALITY GROUP CLASSIFICATIONS ANDSTANDARDS (REVISION 2, JUNE 1975)NO"TE:. Thc'- followngA; is- for histo,-rica,-l prp,,o-,-sc-Gu,4c 1.2 ;apprl;,-,-blc toSan Onofre Units 2 and 3 are consistent with the recommendations of Regulatory Guide 1.26except for the differences indicated below. Implementation is presented in section 3.2.There. is..a diffcrent u..ag. of the term.,
to that, used elsewher...
in., the÷,Regqulations anidRegul26ator Gusoiatds Thetguidelincludesiqcomponents thate falplinsto Qualitprogra inxccp ordane with Handlinq Appednnldix Btshouldibe bapplied.,
Qultye aSsurnFelPo and Liner, and related Fuel Pool structural components.
These are the only remaining safety-related SSCs at SONGS while spent fuel remains in the spent fuel pool.
Document Control Desk-B3
,uch as. thoe-, in, oi or. cmpressed ai sstms Coa-ovcr',,ag-c i- not. extcnd,,4, seventh of the a This- option is ,luded avoid,' an u nano-sar, co~mplicat~ion automatic' closing valves.ln iaof,', IInn rrm l, , The motorF bearing's, oi fo reacntor coolant pump, , incM ,ludng the compone"nt,,'
coolingreqhre for s;cafenl' p' .lant, shutdow, tmP hme lassificaton of this J, eqimen included Qualit3A.1.29.
aarp .. REUA of thIe Reguator GuiSMCDESINCASFCTO RVS1, AUGUST 1973)The San Onofre Units 2 and 3 design is consistent with the recommendations of Regulatory Guide 1.29 except for the differences indicated below. Implementation of this Regulatory Guideis discussed in section 3.2.3A.1.29.1 Paragqraph C.1 .d of the Regqulatory GuideThe spent fuel pool coolinq systems are Seismic Category III.This is interpretedl to includeoanly, those minimum systefms to shut down there actomr it in shtow,,~
n cndiin.4fn Those systoar,-em that"ma bie, used ,optI to' a.normal shutdown or thosea that remov'e res;4,idual heatJll from 'ltl he reacto is notf their prime fu nction, arc,. not designedP for DIE. The operation theceIca IIVVl and I volum control I Is an exampL of tis typ of system. lI ~~llI Document Control Desk B.4-3A.1.29.2 Paragqraph C.l..q of the Regulatory GuideThe associated support systems to the spent fuel pool cooling system are Seismic Category Ill.3A.1.29.2-3 Paragraph C.1 .h of the Regqulatory GuideIt is considered that the motor bearing's oil system for the reactor coolant pumps, including thecomponent coolant water piping and lube oil coolers, should not be Seismic Category I. Sincethe reactor coolant pumps are not required to perform a safety function during accidentconditions, and are not required for safe plant shutdown, the seismic classification of thisequipment is included under Seismic Category I1.3A.1 .29.4 Paragraph C.1 .r of the Regulatory GuideThe associated power systems supplyingl the spent fuel pool cooling system and spent fuel poolmakeup system are Seismic Category Ill.3A.1.29.35 Paragqraph C.2 of the Regulatory GuideItems that would otherwise be classified non-Seismic Category 1, "but whose failure couldreduce the functioning" of items important to safety "to an unacceptable safety level," are to be"designed and constructed so that the DBE would not cause such failure."
In addition, Paragraph C.4 of the guide recommends that the pertinent quality assurance requirement ofAppendix B to 10CFR50 should be applied to the safety requirements" of such items. Both ofthese recommendations are followed by applying the following practices to such items:A. Design and design control for such items are carried out in a similar manner as that foritems directly important to safety. This includes the performance of appropriate designreviews.B. Field work is performed under the direction of the Responsible Work Organization (RWO) Engineer and is inspected by RWO engineers.
The RWO engineers areresponsible for verifying that construction is performed in accordance with the designdrawings and specifications and with applicable standard codes and specifications.
C. Such items are not included on the "Q" List.3A.1.29.46 Paraglraph C.3 of the Regculatory GuideSeismic Category I design requirements are recommended to be extended "to the first seismicrestraint beyond the defined boundaries."
Since seismic analysis of a piping system requiresdivision of the systems into discrete segments terminated by fixed points, this means that theseismic design cannot be terminated at a seismic restraint, but is extended to the first point inthe system that can be treated as an anchor to the plant structure.
In addition, Paragraph C.4 ofthe guide requires that "the pertinent quality assurance requirement of Appendix B to 10CFR50should be applied to the safety requirements" of such items. Both these requirements areconsidered to be met adequately by applying the following practices to such items:
Document Control Desk B.5-A. Design and design control for such items are carried out in a similar manner as that foritems directly important to safety. This includes the performance of appropriate designreviews.B. Field audits are performed by representatives of the Design Engineering Organization (DEO) to assure that the final installation of such items is in accordance with documents that formed the basis for the seismic analysis of the items.C. Such items are not included on the "Q" List.3A.1.76 REGULATORY GUIDE 1.76, DESIGN BASIS TORNADO FOR NUCLEARPOWER PLANTS (REVISION 0, APRIL 1974)An alternative approach was used to establish the design basis tornado as discussed inparagraph 2.3.1.2.2.
In addition, the followingq exception is taken:The spent fuel pool coolinq systems:
associated support systems:
and associated powersystems are not desigqned to withstand tornado missiles.
In addition it is not necessary for theassociated SFP makeup power systems to withstand tornado missiles.