ML20086S402
| ML20086S402 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/18/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20086S393 | List: |
| References | |
| NUDOCS 9508010214 | |
| Download: ML20086S402 (5) | |
Text
..
- i e..L g i
M MS s
}*, -
UNITED STATES l
. p-i j
NUCLEAR REGULATORY _ COMMISSION j
f a
WASHINGTON, D.C. 30086 4001 j
-l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l
RELATED TO AMENDMENT N0.122f0 FACILITY OPERATING LICENSE N0. NPF-10 AND AMEN 0 MENT NO. iiiTO FACILITY OPERATING LICENSE NO. NPF-15 SOUTHERN CALIFORNIA EDISON COMPANY SAN DIEGO GAS AND ELECTRIC COMPANY f
THE CITY OF RIVERSIDE. CALIFORNIA THE CITY OF ANAHEIM. CALIFORNIA SAN ONOFRE NUCLEAR GENERATING STATION. UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362
1.0 INTRODUCTION
By separate letters dated April 30, 1993, as supplemented by letters dated July 6,1994, and letter dated January 27, 1995, Southern California Edison
)
Company, et al. (SCE or the licensee) submitted a request for changes to the Technical Specifications (TS) for San Onofre Nuclear Generating Station
)
(SONGS) Unit 2 and Unit 3.
The proposed changes would revise TS 3/4.4.8.1,
-)
" Pressure-Temperature Limits," TS 3.4.8.3.1, " Overpressure Protection i
Systems-RCS Temperature 5256*F [for Unit 2, s246*F for Unit 3]," TS 3.4.8.3.2, l
" Overpressure Protection Systems-RCS Temperature >256*F [for Unit 2, >246*F for Unit 3]," and the associated TS Bases. The proposed change 1) revises the Reactor Coolant System (RCS) Pressure-Temperature (P-T) limits and the Low Temperature Overpressure Protection (LTOP) enable temperatures to be effective until 20 Effective Full Power Years (EFPY) of operation and 2) makes minor editorial changes.
The July 6, 1994, supplemental letters for each unit and'the January 27, 1995, supplemental letter provided additional clarifying information and did not change the initial no significant hazards consideration determination which was published in the Federal Reaister on July 7, 1993 (58 FR 36445) for Unit 2 and June 23, 1993 (58 FR 34094) for Unit 3.
2.0 DISCUSSION
. The maximum allowable RCS pressure at any temperature is based upon the stress limitations for brittle fracture. TS 3/4.4.8.1, " Reactor Coolant System-Pressure Temperature Limits," provides operational constraints in all modes of i
9508010214 950718 ADOCK 0500 1
gDR i
.... reactor operation to ensure that the most stress limiting location in the reactor vessel is not susceptible to brittle failure as a consequence of reactor operations. The neutron-induced embrittlement of the reactor vessel wall also affects the temperature below which LTOP is required.
LTOP is provided by the shutdown cooling system (SDCS) relief valve.
The SDCS relief valve must be aligned below the specified temperature to provide assurance that the reactor vessel wall will be operated in the ductile region in accordance with 10 CFR 50 Appendix G during both normal operation and overpressurization events due to equipment malfunction or operator error. The existing TS require alignment of the SDCS relief valve below the temperature corresponding to the P-T curve pressurizer relief valve setpoint of 2500 psia.
1 The existing TS RCS P-T limit curves in TS 3/4.4.8, Figures 3.4-2 and 3.4-3, were originally valid for 8 EFPY of plant operation.
The proposed TS P-T limit curves will be valid for 20 EFPY of plant operation.
The proposed LTOP enable temperatures represent the most limiting temperatures for normal heatup, normal cooldown, and remote shutdown cooldown operations.
Below these LTOP enable temperatures the SDCS relief valve must be aligned during heatup operations and during cooldown operations from either the remote j
shutdown panels or the control room.
Due to the proposed TS changes, the Updated Final Safety Analysis Report (UFSAR) will be revised to reflect the (1) LTOP enable temperatures for heatup and cooldown operations, and (2) updated material properties evaluated in response to Generic Letter (GL) 92-01, Revision 1, " Reactor Vessel Structural Integrity,10 CFR 50.54(f)."
3.0 EVALUATION The staff evaluated the proposed P-T limits based on the following NRC regulations and guidance: Appendix G to 10 CFR Part 50; GLs 88-11 and 92-01; Regulatory Guide (RG) 1.99, Rev. 2; and Standard Review Plan (SRP) Section 5.3.2.
The proposed changes to the LTOP enable temperatures were evaluated using the guidance provided in SRP 5.2.2 Branch Technical Position RSB 5-2.
Appendix G to 10 CFR Part 50 requires that P-T limits for the reactor vessel must be at least as conservative as those obtained by Appendix G to Section III of the ASME Code. GL 88-11 provides that licensees may use the methods in RG 1.99, Rev. 2, to predict the effect of neutron irradiation by calculating adjusted reference temperature (ART) of reactor vessel materials.
The ART is defined as the sum of initial nil-ductility transition reference temperature and.,) of the material, the increase in RT ' the prediction method.
(RT caused by neutron irradiation, amargintoaccountforuncertaintiesIn The increase in RT., The chemistry factor is dependent upon the amount of copper is calculated from the product of a chemistry factor and a fluence factor.
and nickel in the vessel material.
GL 92-01 requires licensees to submit reactor vessel materials data, which the staff will use in the review of the P-T limits submittals.
SRP 5.3.2 provides guidance on calculation of the P-T limits using linear elastic fracture mechanics methodology specified in Appendix G to Section III of the ASME Code.
In a letter dated January 27, 1995, the licensee provided additional technical information to explain how
r q
5
- e,.
- the proposed P-T limits comply with the NRC regulations and guidance described above.
For the Unit 2 reactor vessel, the licensee determined that base plates C-6404-5 and C-6404-1 are the limiting materials at the 1/4T and 3/4T-
. locations, respectively (T - the thickness of the reactor vessel beltline).
The licensee calculated an ART of 129'F at the 1/4T location and 106.5'F at the 3/4T location. The input variables for the ART calculations are shown in Table 1.
For the Unit 3 reactor vessel, the licensee determined that base plate C-6802-1 is the limiting material for both the 1/4T and 3/4T locations. The licensee calculated an ART of 116*F at the 1/4T location and an ART of 99.8'F-at the 3/4T location.
The staff verified that the copper and nickel contents'and initial RT,the NRC used by the licensee in their analysis were in agreement with the values in reactor vessel material database. The staff used the' material properties to perform an independent calculation of the ART values for the limiting materials using RG 1.99, Rev. 2.
Based on the staff's calculation, the staff verified that the licensee's calculated ARTS are acceptable.
By substituting the ARTS from the attached Table into the equations listed in SRP 5.3.2, the staff verified that the proposed P-T limits for heatup, cooldown, criticality, and inservice hydrostatic test satisfy the requirements in Paragraphs IV.A.2 and IV.A.3 of Appendix G of 10 CFR Part 50.
In addition to beltline materials, Appendix G of 10 CFR Part 50 also imposes a minimum temperature at the closure head flange based on the reference temperature for the flange material.Section IV.A.2 of Appendix G states that when the pressure exceeds 20% of the preservice system hydrostatic test pressure, the temperature of the closure flange regions highly stressed by the bolt preload must exceed the reference temperature of the material in those regions by at least 120*F for normal operation and by 90*F for hydrostatic pressure tests and leak tests. Based on the flange RT of 40*F provided by the licensee, the staff has determined that the propos,ed P-T limits have satisfied the requirement for the closure flange region during normal operation, hydrostatic pressure test and leak test.
The staff has performed an independent analysis to verify the licensee's proposed P-T limits. The staff concludes that the proposed P-T limits for heatup, cooldown, inservice hydrostatic test, and criticality are valid for 20 effective full power years because (1) the limits conform to the requirements of Appendix G of 10 CFR Part 50 and GL 88-11, and (2) the material properties and chemistry used in calculating the P-T limits are consistent with data submitted under GL 92-01.
Hence, the proposed P-T limits are acceptable for incorporation into the San Onofre Units 2 and 3 TS.
The staff has reviewed the analysis performed by the licensee to support the proposed changes to the LTOP enable temperatures, and has determined that the analysis is in accordance with SRP Branch Technical Position (BTP) RSB 5-2,
<, jxc I
. wg :
Revision 1, "Overpressurization Protection of Pressurized Water Reactors While Operating at Low Temperatures." BTP RSB 5-2, Revision I defines the LTOP enable temperature as "the water temperature corresponding to a metal temperature of at least RT"dpp+endix G limit calculations."90*F at the beltline location that is controlling in the This calculational _
~
basis changes the LTOP alignment temperature from 312*F to 256*F for Unit 2, and from 302*F to 246*F for. Unit 3.
The P-T limits will not be exceeded by~
postulated overpressurization transients with the SDCS relief valve aligned to l
the RCS system at the proposed LTOP enable temperatures. Therefore, the proposed LTOP enable temperature change is acceptable to the staff.
1
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the California State official was notified of the proposed issuance of the amendment.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements.
The NRC staff has determined-that the amendments involve no significant increase in the amounts, and no
(
significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual'or. cumulative occupational radiation exposure. The Commission has previously issued a-i proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (58 FR 36445 and 58 FR 34094). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 CONCLUS!0N The Commission has concluded, based on the considerations discussed above, that-(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commiission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Attachment:
Table Principal Contributor: John Tsao, NRR Date:
July 18, 1995 i
)
1-
r=
r, l
Table ADJUSTED REFERENCE TEMPERATURE FOR REACTOR VESSEL LIMITING MATERIALS FOR PRESSURE-TEMPERATURE LIMITS 20 EFFECTIVE FULL POWER YEARS SAN ON0FRE UNITS 2 AND 3 Limiting Cu Ni Fluence ART,n Initial Margin ART Materials:
RT,n Plates Unit 2 C6404-5 (1/4T)
.11
.64 1.625 85 10 34 129 C6404-1 (3/4T)
.10
.56 0.503 52.5 20 34 106.5 Unit 3 C6802-1 (1/4T)
.06
.58 1.625 42 40 34 116 C6802-1 (3/4T)
.06
.58 0.503 29.9 40 29.9 99.8 Fluence units are in 10" neutron /cm 2
j 1
i