ML20117J443
| ML20117J443 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/29/1996 |
| From: | Nunn D SOUTHERN CALIFORNIA EDISON CO. |
| To: | |
| Shared Package | |
| ML20117J437 | List: |
| References | |
| NUDOCS 9605310176 | |
| Download: ML20117J443 (9) | |
Text
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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Application of SOUTHERN CALIFORNIA l
EDIS0N COMPANY, _ET.A_L. for a Class 103 Docket No. 50-361 License to Acquire, Possess, and Use a Utilization Facility as Part of Amendment Application Unit.No. 2 of the San Onofre Nuclear No. 162 Generating Station l
SOUTHERN CALIFORNIA EDIS0N COMPANY, ET AL. pursuant to 10 CFR 50.90, hereby submit Amendment Application No. 162. This amendment application consists of Proposed Change Number NPF-10-465 to Facility Operating License No. NPF-10.
Proposed Change Number NPF-10-465 is a request to change the Unit 2 Amendment No. 127 approved Technical Specification 3.5.1, " Safety Injection Tanks (SITS),"
minimum boron concentration in the safety injection tanks from 1850 ppm to 2200 ppm.
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9605310176 960529 PDR ADOCK 05000361 p
Subscribed on thisk b'
1996.
day of
/
C Respectfully submitted, SOUTHERN CALIFORNIA EDIS0N COMPANY 1
By: -
Dwight E. Nun Vice President State of California Count of S n Diego E
On before me,!)
h(M i
b, personally appeared
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b lA_fL/, personally known to me to be the person whose name is subscribed to the within instrument f
and acknowledged to me that he executed the same in his authorized capacity, and that by his signature on the instrument the person, or the entity upon behalf of which the person acted, executed the instrument.
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-.m WITNESS'ny hand and official seal.
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f Notary PubEc - CoEfornia f Comm.ExpirosOCT14.1998 f" ORANGE COUN1Y Signat e d
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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Application of SOUTHERN CALIFORNIA EDISON COMPANY, ET AL. for a Class 103 Docket No. 50-362 License to Acquire, Possess, and Use a Utilization Facility as Part of Amendment Application Unit No. 3 of the San Onofre Nuclear No. 146 Generating Station SOUTHERN CALIFORNIA EDIS0N COMPANY, EI AL. pursuant to 10 CFR 50.90, hereby submit Amendment Application No. 146.
This amendment application consists of Proposed Change Number NPF-15-465 to Facility Operating License No. NPF-15.
Proposed Change Number NPF-15-465 is a request to change the Unit 3 Amendment No.116 approved Technical Specification 3.5.1, " Safety Injection Tanks (SITS),"
minimum boron concentration in the safety injection tanks from 1850 ppm to 2200 ppm.
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1 Subscribed on this M W 1 day of N'l/L644 1996.
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Re:pectfully submitted, SOUTHERN CALIFORNIA EDIS0N COMPANY T
By:
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Dwight E. Nunn I
Vice President i
t State of California Count f Sa Diego
[l h f $ (0 before me Yllkfik)
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on personallyappearedhOf _ /vb b, k W, personally known to me to be the person whose name is subscribed to the within instrument and acknowledged to me that he executed the same in his authorized capacity, and that by his signature on the instrument the person, or the entity upon behalf of which the person acted, executed the instrument.
MARANE SANCHEZ f
WITNESS y hand and official seal.
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ORANGE COUNTY
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Enclosure DESCRIPTION AND SAFETY ANALYSIS OF PROPOSED CHANGE NPF-10/15-465 Proposed Change Number 465 (PCN-465) is a request to revise the Unit 2 Amendment No.127 and Unit 3 Amendment No.116 approved Technical Specification (TS) 3.5,
" Emergency Core Cooling Systems (ECCS)." Specifically, TS 3.5.1, " Safety Injection Tanks (SITS)" is being revised to increase the minimum required boron concentration.
Existina Specifications:
Unit 2:
See Attachment "A" Unit 3:
See Attachment "B" Revised Specifications:
Unit 2:
See Attachment "C" Unit 3:
See Attachment "D" SU W RY gf CHANGE Southern California Edison (Edison) is extending the operating cycle to approximately 590 effective full power days. To accomplish this cycle length extension Edison is increasing the initial Uranium-235 fuel enrichment above 4.1 w/o up to 4.8 w/o and changing the burnable poison from B C to Erbia.
Erbia is g
an Asea Brown Boveri Combustion Engineering Nuclear Organization (ABB CEN0) term i
used to describe an Erbium-0xide Er,0 and fuel mixture. To support this cycle l
3 length extension the minimum boron concentration in the safety injection tanks needs to be increased from 1850 parts per million (ppm) to 2200 ppm.
Edison believes this change in the SIT minimum boron concentration limit is, in essence, an administrative change. The SITS are filled from the refueling water storage tank (RWST), which has a technical specification minimum baron concentration requirement of 2350 ppm.
Edison maintains the RWST boron concentration higher than the minimum limit, and, as a result, for the past several years the SIT boron concentration has been approximately 2500 ppm, even though the technical specification lower limit is 1850 ppm. Therefore, changing the SIT minimum boron concentration from 1850 ppm to 2200 ppm does not involve a physical change to the plant.
PROPOSED TECHNICAL SPECIFICATION CHANGES PCN 465 requests to change the following Surveillance Requirement (SR) as shown (line out for deletion and highlight for addition):
e SR 3.5.1.4: Verify boron concentration in each SIT is a M60 2200 ppm and s 2800 ppm.
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- SYSTEM DESCRIPTIONS Safety Injection Tanks (SIT):
The function of the four SITS is to supply water to the reactor vessel after the blowdown phase of a loss of coolant accident (LOCA), to provide inventory to refill the recctor vessel, and recover the fuel.
The blowdown phase of.a large break LOCA is the initial period of. the transient during which the Reactor Coolant System (RCS) departs from' equilibrium conditions, and heat from fission product decay, hot internals, and the vessel continues to be transferred to the reactor coolant. The blowdown phase of t'ie transient ends when the RCS pressure falls to a value approaching that of the containment atmosphere.
The refill phase of a LOCA follows immediately to replace the reactor coolant inventory lost from the break. The core, during this time, is essentially in adiabatic heat up. The SIT inventory is available to fill the lower plenum and reactor vessel downcomer establishing a recovery level at the bottom of the core. This facilitates reflood of the core with the addition of water by the Emergency Core Cooling System (ECCS) from the Refueling Water Storage Tank (RWST) and the Boric Acid Make Up (BAMU) tanks.
The Sirs are pressure vessels partially filled with borated water and pressurized with nitrogen gas. The SITS are passive components, since no operator or control action is required for them to perform their function.
Internal tank pressure is sufficient to discharge the contents to the RCS when RCS pressure decreases below the SIT pressure.
i Each SIT is piped into one RCS cold leg via the injection lines utilized by the r
High Pressure Safety Injection and Low Pressure Safety Injection (HPSI and LPSI) systems. Each SIT is isolated from the RCS by a motor operated isolation valve and two check valves in series. The motor operated isolation valves are normally open, with power removed from the valve motor to prevent inadvertent i
closure prior to or during an accident.
DISCUSSI0J Current Boron Concentration Requirements The SITS have a minimum boron concentration limit to ensure the reactor remains subcritical by at least 1% shutdown margin (Mode 3) during the post LOCA refill, J
reflood, and recirculation phases. The SITS have a maximum limit on boron j
concentration to prevent boron precipitation from the coolant during the post LOCA time frame.
I The SIT minimum boron requirement is based on beginning of life reactivity values and is selected to ensure that the reactor will remain subcritical during the refill stage of a large break LOCA. During a large break LOCA, no control element assembly (CEA) is assumed to insert into the core. The initial reactor shutdown is accomplished by void formation due to depressurization.
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. l Sufficient boron conce.ntration must be maintained in the SITS to prevent a i
return to criticality during the core refill. The minimum SIT boron concentration is based upon the requirement to maintain the reactor core subcritical without assistance from the CEAs or any other boron source.
Proposed Boron Concentration Requirements:
t Edison is increasing the fuel enrichment up to 4.8 w/o and changing the burnable poison from B C to Erbia to achieve a longer cycle length. Erbia is an ABB CEN0 i
g term to describe an Erbium-0xide Er 0 and fuel mixture.
This change in core 23 configuration requires additional negative reactivity at the start of the fuel cycle. The calculations show that for the SITS to perform their design function post-LOCA the minimum required boron concentration needs to be increased from
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1850 ppm to 2200 ppm.
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The upper limit on SIT boron concentration is set to ensure boron precipitation will not occur during post LOCA recirculation. No change in the upper boron i
. concentration limit is required to maintain this acceptance criteria. No other l
accident conditions, design conditions, Technical Specifications, or Technical Specification Bases are affected by this proposed change in boron concentration.
Attachment E provides a technical summary of the boron concentration change calculations that were performed to support the Cycle 9 reload analysis.
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Impact on Plant Operations Edison believes this change.in the SIT minimum boron concentration limit is, in essence, an administrative change. The SITS are filled from the refueling water.
storage tank (RWST), which has a technical specification minimum boron concentration requirement of 2350 ppm. Edison maintains the RWST boron concentration higher than the minimum limit, and, as a result, for the past several years the SIT boron concentration has been approximately 2500 ppm, even though the technical specification lower limit is 1850 ppm. The maximum boron concentration limit is not being changed.
Increasing the SIT minimum boron concentration limit of the technical specification narrows the existing operating band,and ma ntaining the boron concentration between 2200 ppm and 2800 ppm will keep the boron concentration between the current band of 1850 ppm to 2800 ppm.
Therefore, changing the SIT minimum boron concentration from 1850 ppm to 2200 ppm does not involve a physical change to the plant, nor will it impact.
plant operations.
SAFETY ANALYSIS The proposed change described above shall be deemed to involve a significant hazards consideration if there is a positive finding in any one of the following areas:
1.
Will operation of the facility in accordance with this proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?
Response: No Southern California Edison (Edison) is increasing the minimum boron concentration to maintain the ability of the Safety Injection Tanks
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. (SITS) to perform their intended safety function consistent with the increase in fuel enrichment up to 4.8 weight percent (w/o)
Uranium-235 and changing the burnable poison from B C to Erbia 4
4 (Erbium-0xide Er 0 and fuel mixture) to. increase the length of the operating cycle.2 3 Increasing the minimum boron concentration in the SITS will maintain the ability of the Emergency Core Cooling System (ECCS) to control core reactivity during and following an accident.
No change is being made to the design of the safety injection system.
Consequently, there will be no impact on.the probability of initiating an accident which has been previously evaluated.
Increasing the boron concentration in the SITS will ensure'the l
ability of this system to mitigate the accidents for which it is required. No other accident conditions, design conditions, Technical Specifications, or Technical Specification Bases are affected by this proposed-change'in boron concentration.-
l Therefore, the operation of the facility in accordance with this j
proposed change does not involve an increase in the probability or i
consequences of an accident previously evaluated.
2.
Will operation of the facility in accordance with this proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?
Response: No There is no change in plant design or operational methodology imposed by the increase in SIT boron concentration. This increase in boron concentration is required because Edison is increasing the fuel enrichment up to 4.8 w/o Uranium-235 and changing the burnable poison from B,C to Erbia to achieve a longer cycle length.
Therefore, additional negative reactivity is required at the beginning of the fuel cycle for these alternate coolant sources.
Edison believes this change in the SIT minimum boron concentration limit is, in essence, an administrative chan The SITS are filled
'from the refueling water storage tank (RWST)ge., which has a technical specification minimum boron concentration requirement of 2350 ppm.
Edison maintains the RWST boron concentration higher than the minimum limit. As a result, for the past several years the SIT boron concentration has been approximately 2500 ppm, even though the technical specification lower limit is 1850 ppm.
The maximum boron concentration limit is not being changed.
Increasing the SIT minimum boron concentration limit of the technical specification narrows the existing operating band, and maintaining the boron concentration between 2200 ppm and 2800 ppm will keep the boron concentration between the current band of 1850 ppm to 2800 ppm.
Therefore, changing the SIT minimum boron concentration from 1850 ppm to 2200 ppm does not involve a physical change to the plant.
Therefore, the operation of the facility in accordance with this proposed change does not create the possibility of a new or
. different kind of accident from eny accident previously evaluated.
3.
Will operation of the facility in accordance with this proposed change involve a significant reduction in a margin of safety?
Response: No With the increase in fuel enrichment up to 4.8 w/o Uranium-235 and changing the burnable poison from B C to Erbia to increase the 4
length of the operating cycle, increasing the minimum boron concentration in the SITS is required to maintain the current j
margins of safety.
The calculations were performed to ensure the core remains subcritical (i.e., conservatively 1% shutdown) with the proposed boron concentration.
In addition to the conservative assumptions used in the calculation, 50 ppm was added to the results.
Therefore, the operation of the facility in accordance with this proposed change does not involve a significant reduction in a margin of safety.
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Safety and Sionificant Hazards Determination Based on the above Safety Analysis, it is concluded that:
(1) the proposed change does not constitute a significant hazards consideration as defined by 10 CFR 50.92; and (2) there is reasonable assurance that the health and' safety of the public will not be endangered by the proposed change. Moreover, because this action does not involve a significant hazards consideration, it will also not result in a condition which significantly alters the impact of the Station on the environment as described in the NRC Final Environmental Statement.
i NPF-10/15-465 i
l ATTACHMENT "A" EXISTING SPECIFICATIONS UNIT 2
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