ML26043A346
| ML26043A346 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  (DPR-080, DPR-082) |
| Issue date: | 02/23/2026 |
| From: | Samson Lee NRC/NRR/DORL/LPL4 |
| To: | Gerfen P Pacific Gas & Electric Co |
| Lee S, NRR/DORL/LPL4 | |
| References | |
| EPID L-2024-LLA-0177 | |
| Download: ML26043A346 (0) | |
Text
February 23, 2026 Ms. Paula Gerfen Senior Vice President, Generation and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 56, Mail Code 104/6 Avila Beach, CA 93424
SUBJECT:
DIABLO CANYON NUCLEAR POWER PLANT, UNITS 1 AND 2 - ISSUANCE OF AMENDMENT NOS. 256 AND 258 RE: REVISION TO TECHNICAL SPECIFICATIONS TO ADOPT TSTF-505, REVISION 2, PROVIDE RISK-INFORMED EXTENDED COMPLETION TIMES - RITSTF INITIATIVE 4b FOR TECHNICAL SPECIFICATIONS 3.3.1 AND 3.3.2 (EPID L-2024-LLA-0177)
Dear Ms. Gerfen:
The U.S. Nuclear Regulatory Commission (NRC, the Commission) has issued the enclosed Amendment No. 256 to Facility Operating License No. DPR-80 and Amendment No. 258 to Facility Operating License No. DPR-82 for the Diablo Canyon Nuclear Power Plant, Units 1 and 2 (Diablo Canyon), respectively. The amendments consist of changes to the technical specifications (TSs) in response to your application dated December 24, 2024, as supplemented by letter dated November 26, 2025.
The amendments revise the Diablo Canyon TSs to permit the use of risk-informed completion times for actions to be taken when limiting conditions for operation are not met for TS 3.3.1, Reactor Trip System (RTS) Instrumentation, and TS 3.3.2, Engineered Safey Features Actuation System (ESFAS) Instrumentation. The changes are based on Technical Specifications Task Force (TSTF) Traveler TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF [Risk-Informed TSTF] Initiative 4b, dated July 2, 2018.
The NRC staff issued a final model safety evaluation approving TSTF-505, Revision 2, on November 21, 2018.
A copy of the related safety evaluation is enclosed. Notice of Issuance will be included in the Commissions monthly Federal Register notice.
Sincerely,
/RA/
Samson S. Lee, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-275 and 50-323
Enclosures:
- 1. Amendment No. 256 to DPR-80
- 2. Amendment No. 258 to DPR-82
- 3. Safety Evaluation cc: Listserv
PACIFIC GAS AND ELECTRIC COMPANY DOCKET NO. 50-275 DIABLO CANYON NUCLEAR POWER PLANT, UNIT 1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 256 License No. DPR-80
- 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Pacific Gas and Electric Company (the licensee), dated December 24, 2024, as supplemented by letter dated November 26, 2025, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in 10 CFR Chapter I; B.
The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.
There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commissions regulations; D.
The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.
The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.
- 2.
Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Facility Operating License No. DPR-80 is hereby amended to read as follows:
(2)
Technical Specifications The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 256, are hereby incorporated in the license. Pacific Gas & Electric Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan, except where otherwise stated in specific license conditions.
- 3.
This license amendment is effective as of its date of issuance and shall be implemented within 180 days of the date of issuance.
FOR THE NUCLEAR REGULATORY COMMISSION Michael Mahoney, Acting Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Attachment:
Changes to Facility Operating License No. DPR-80 and the Technical Specifications Date of Issuance: February 23, 2026 MICHAEL MAHONEY Digitally signed by MICHAEL MAHONEY Date: 2026.02.23 12:22:30 -05'00'
PACIFIC GAS AND ELECTRIC COMPANY DOCKET NO. 50-323 DIABLO CANYON NUCLEAR POWER PLANT, UNIT 2 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 258 License No. DPR-82
- 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Pacific Gas and Electric Company (the licensee), dated December 24, 2024, as supplemented by letter dated November 26, 2025, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in 10 CFR Chapter I; B.
The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.
There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commissions regulations; D.
The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.
The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.
- 2.
Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Facility Operating License No. DPR-82 is hereby amended to read as follows:
(2)
Technical Specifications (SSER 32, Section 8)* and Environmental Protection Plan The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 258, are hereby incorporated in the license. Pacific Gas & Electric Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan, except where otherwise stated in specific license conditions.
- 3.
This license amendment is effective as of its date of issuance and shall be implemented within 180 days of the date of issuance.
FOR THE NUCLEAR REGULATORY COMMISSION Michael Mahoney, Acting Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Attachment:
Changes to Facility Operating License No. DPR-82 and the Technical Specifications Date of Issuance: February 23, 2026 MICHAEL MAHONEY Digitally signed by MICHAEL MAHONEY Date: 2026.02.23 12:22:57 -05'00'
ATTACHMENT TO LICENSE AMENDMENT NO. 256 TO FACILITY OPERATING LICENSE NO. DPR-80 AND LICENSE AMENDMENT NO. 258 TO FACILITY OPERATING LICENSE NO. DPR-82 DIABLO CANYON NUCLEAR POWER PLANT, UNITS 1 AND 2 DOCKET NOS. 50-275 AND 50-323 Replace the following pages of Facility Operating License Nos. DPR-80 and DPR-82, and the Appendix A, Technical Specifications, with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.
Facility Operating License No. DPR-80 REMOVE INSERT Facility Operating License No. DPR-82 REMOVE INSERT Technical Specifications REMOVE INSERT 3.3-1 3.3-1 3.3-2 3.3-2 3.3-3 3.3-3 3.3-4a 3.3-4a 3.3-5 3.3-5 3.3-6 3.3-6 3.3-7 3.3-7 3.3-19 3.3-19 3.3-19a 3.3-20 3.3-20 3.3-21 3.3-21 3.3-22 3.3-22 3.3-23 3.3-23 3.3-24 3.3-24 3.3-24a 3.3-24a Amendment No. 256 (4)
Pursuant to the Act and 10 CFR Parts 30, 40, and 70, to receive, possess, and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; and (5)
Pursuant to the Act and 10 CFR Parts 30, 40, and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.
C.
This License shall be deemed to contain and is subject to the conditions specified in the Commissions regulations set forth in 10 CFR Chapter I and is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:
(1)
Maximum Power Level The Pacific Gas and Electric Company is authorized to operate the facility at reactor core power levels not in excess of 3411 megawatts thermal (100% rated power) in accordance with the conditions specified herein.
(2)
Technical Specifications The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 256 are hereby incorporated in the license.
Pacific Gas & Electric Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan, except where otherwise stated in specific license conditions.
(3)
Initial Test Program The Pacific Gas and Electric Company shall conduct the post-fuel-loading initial test program (set forth in Section 14 of Pacific Gas and Electric Companys Final Safety Analysis Report, as amended), without making any major modifications of this program unless modifications have been identified and have received prior NRC approval. Major modifications are defined as:
a.
Elimination of any test identified in Section 14 of PG&Es Final Safety Analysis Report as amended as being essential; Amendment No. 258 (4)
Pursuant to the Act and 10 CFR Parts 30, 40, and 70, to receive, possess, and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; and (5)
Pursuant to the Act and 10 CFR Parts 30, 40, and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.
C.
This License shall be deemed to contain and is subject to the conditions specified in the Commissions regulations set forth in 10 CFR Chapter I and is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:
(1)
Maximum Power Level The Pacific Gas and Electric Company is authorized to operate the facility at reactor core power levels not in excess of 3411 megawatts thermal (100% rated power) in accordance with the conditions specified herein.
(2)
Technical Specifications (SSER 32, Section 8)* and Environmental Protection Plan The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 258, are hereby incorporated in the license.
Pacific Gas & Electric Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan, except where otherwise stated in specific license conditions.
(3)
Initial Test Program (SSER 31, Section 4.4.1)
Any changes to the Initial Test Program described in Section 14 of the FSAR made in accordance with the provisions of 10 CFR 50.59 shall be reported in accordance with 50.59(b) within one month of such change.
- The parenthetical notation following the title of many license conditions denotes the section of the Safety Evaluation Report and/or its supplements wherein the license condition is discussed.
RTS Instrumentation 3.3.1 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 1 of 60 Tab_3!3u3r19.DOC 1106.1629 3.3 INSTRUMENTATION 3.3.1 Reactor Trip System (RTS) Instrumentation LCO 3.3.1 The RTS instrumentation for each Function in Table 3.3.1-1 shall be OPERABLE.
APPLICABILITY:
According to Table 3.3.1-1.
ACTIONS
NOTE------------------------------------------------------------
Separate Condition entry is allowed for each Function.
CONDITION REQUIRED ACTION COMPLETION TIME A.
One or more Functions with one or more required channels or trains inoperable.
A.1 Enter the Condition referenced in Table 3.3.1-1 for the channel(s) or trains.
Immediately B.
One Manual Reactor Trip channel inoperable.
B.1 Restore channel to OPERABLE status.
48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> OR In accordance with the RICT Program
NOTE-----------------
While this LCO is not met for function 19, 20 or 21, in MODE 5, making the Rod Control System capable of rod withdrawal is not permitted.
C.
One channel or train inoperable.
C.1 Restore channel or train to OPERABLE status.
OR C.2.1 Initiate action to fully insert all rods.
48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> 48 hours (continued) 3.3-1 Unit 1 - Amendment No. 135, 142, Unit 2 - Amendment No. 135, 142, 256 258
RTS Instrumentation 3.3.1 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 2 of 60 Tab_3!3u3r19.DOC 1106.1629 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME C.
(continued)
AND C.2.2 Place the Rod Control System in a condition incapable of rod withdrawal.
49 hours5.671296e-4 days <br />0.0136 hours <br />8.101852e-5 weeks <br />1.86445e-5 months <br /> D.
One Power Range Neutron Flux-High channel inoperable.
NOTE------------------
The inoperable channel may be bypassed for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for surveillance testing and setpoint adjustment of other channels.
D.1.1 -----------NOTE---------------
Only required when the Power Range Neutron Flux input to QPTR is inoperable.
Perform SR 3.2.4.2.
12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> from discovery of THERMAL POWER
> 75% RTP AND Once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter AND D.1.2 Place channel in trip 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR In accordance with the RICT Program (continued) 3.3-2 Unit 1 - Amendment No. 135, 179, Unit 2 - Amendment No. 135, 181, 256 258
RTS Instrumentation 3.3.1 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 3 of 60 Tab_3!3u3r19.DOC 1106.1629 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME E.
One channel inoperable.
NOTE------------------
For functions 6, 7, and 8.b, the inoperable channel and/or one additional channel may be surveillance tested with one channel in bypass and one channel in trip for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, or both the inoperable and the additional channel may be surveillance tested in bypass for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. For functions 2.b and 3, only the inoperable channel may be bypassed for surveillance testing of other channels. For function 14.a, the inoperable channel and/or one additional channel may be surveillance tested with one channel in bypass and one channel in trip for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
This note is not intended to allow simultaneous testing of coincident channels on a routine basis E.1 Place channel in trip.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR In accordance with the RICT Program F.
One Intermediate Range Neutron Flux channel inoperable.
F.1 Reduce THERMAL POWER to < P-6.
OR F.2 Increase THERMAL POWER to > P-10.
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 24 hours (continued) 3.3-3 Unit 1 - Amendment No. 135, 142, 158, 173, 179, 205, Unit 2 - Amendment No. 135, 142, 159, 175, 181, 206, 256 258
RTS Instrumentation 3.3.1 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 6 of 60 Tab_3!3u3r19.DOC 1106.1629 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME M.
One channel inoperable.
NOTE-----------------
For function 8.a, the inoperable channel and/or one additional channel may be surveillance tested with one channel in bypass and one channel in trip for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, or both the inoperable and the additional channel may be surveillance tested in bypass for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. For functions 9 and 10, the inoperable channel and/or one additional channel may be surveillance tested with one channel in bypass and one channel in trip for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
For functions 12 and 13, only the inoperable channel may be bypassed for surveillance testing of other channels. This note is not intended to allow simultaneous testing of coincident channels on a routine basis.
M.1 Place channel in trip.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR In accordance with the RICT Program N.
One channel inoperable N.1 Place channel in trip OR N.2 Reduce THERMAL POWER to < P-7 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 12 hours (continued) 3.3-4a Unit 1 - Amendment No. 135, 158, 173, 179, Unit 2 - Amendment No. 135, 159, 175, 181, 256 258
RTS Instrumentation 3.3.1 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 7 of 60 Tab_3!3u3r19.DOC 1106.1629 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME O.
One Low Auto-Stop Oil Pressure Turbine Trip channel inoperable
NOTE------------------
An inoperable channel may be bypassed for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for surveillance testing of other channels.
O.1 Place channel in trip.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR In accordance with the RICT Program P.
One or more Turbine Stop Valve Closure, Turbine Trip channel(s) inoperable.
P.1 Place channel(s) in trip.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR In accordance with the RICT Program Q.
One train inoperable.
NOTE------------------
One train may be bypassed for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for surveillance testing provided the other train is OPERABLE.
Q.1 Restore train to OPERABLE status.
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> OR In accordance with the RICT Program R.
One RTB train inoperable.
NOTE----------------
One train may be bypassed for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for surveillance testing provided the other train is OPERABLE.
R.1 Restore train to OPERABLE status.
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> OR In accordance with the RICT Program (continued) 3.3-5 Unit 1 - Amendment No. 135, 179, Unit 2 - Amendment No. 135, 181, 256 258
RTS Instrumentation 3.3.1 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 8 of 60 Tab_3!3u3r19.DOC 1106.1629 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME S.
One or more channels or trains inoperable.
S.1 Verify interlock is in required state for existing unit conditions.
1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 7 hours T.
One or more channels or trains inoperable.
T.1 Verify interlock is in required state for existing unit conditions.
OR T.2 Be in MODE 2.
1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 7 hours U.
One trip mechanism inoperable for one RTB.
U.1 Restore trip mechanism to OPERABLE status.
48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> OR In accordance with the RICT Program V.
Not used W. One channel inoperable
NOTE------------------
The inoperable channel may be bypassed for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for surveillance or maintenance.
W.1 Place channel in trip OR W.2 Be in MODE 3 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 12 hours (continued) 3.3-6 Unit 1 - Amendment No. 135, 179, Unit 2 - Amendment No. 135, 181, 256 258
ACTIONS (continued)
CONDITION X.
One or more SG Water Level Low - Low Trip Time Delay channel(s) inoperable.
Y.
Required Action and associated Completion Time of Conditions B, D, E, Q, R, U, and X not met.
- z.
Required Action and associated Completion Time of Condition M not met.
AA. Required Action and associated Completion Time of Conditions O or P not met.
DIABLO CANYON - UNITS 1 & 2 REQUIRED ACTION
NO TE------------------
For function 14.b, the inoperable TTD channel (processor) and/or one additional TTD channel (processor) may be surveillance tested with the affected steam generator low-low water level channels for one TTD channel (processor) in bypass and the affected SG low-low water level channels for the other TTD channel (processor) in trip for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. This note is not intended to allow simultaneous testing of multiple TTD channels (processors) on a routine basis.
X.1 Set the Trip Time Delay to zero seconds.
OR X.2 Place the affected SG Water Level Low - Low channel(s) in trip.
Y.1 Be in MODE 3.
Z.1 Reduce THERMAL POWER to< P-7.
AA.1 Reduce THERMAL POWER to< P-9.
RTS Instrumentation 3.3.1 COMPLETION TIME 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 72 hours OR
NOTE----------
Not applicable when two or more required channels are inoperable.
In accordance with the RICT Program 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 6 hours 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 3.3-7 Unit 1 - Amendment No. 4-Je, 4-+-J, 4+9, Unit 2 - Amendment No. 4Je, 4--7-a, 4-&i, 256 258
ESFAS Instrumentation 3.3.2 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 22 of 60 Tab_3!3u3r19.DOC 1106.1629 3.3 INSTRUMENTATION 3.3.2 Engineered Safety Feature Actuation System (ESFAS) Instrumentation LCO 3.3.2 The ESFAS instrumentation for each Function in Table 3.3.2-1 shall be OPERABLE.
APPLICABILITY:
According to Table 3.3.2-1.
ACTIONS
NOTE-------------------------------------------------------------
Separate Condition entry is allowed for each Function.
CONDITION REQUIRED ACTION COMPLETION TIME A.
One or more Functions with one or more required channels or trains inoperable.
A.1 Enter the Condition referenced in Table 3.3.2-1 for the channel(s) or train(s).
Immediately B.
One channel or train inoperable.
B.1 Restore channel or train to OPERABLE status.
48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> OR In accordance with the RICT Program C.
One train inoperable.
NOTE-----------------
One train may be bypassed for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for surveillance testing provided the other train is OPERABLE.
C.1 Restore train to OPERABLE status.
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> OR In accordance with the RICT Program (continued) 3.3-19 Unit 1 - Amendment No. 135, 179, 219, Unit 2 - Amendment No. 135, 181, 221, 256 258
ESFAS Instrumentation 3.3.2 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 23 of 60 Tab_3!3u3r19.DOC 1106.1629 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME D.
One channel inoperable.
NOTE-----------------
For function 1.d, the inoperable channel and/or one additional channel may be surveillance tested with one channel in bypass and one channel in trip for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, or both the inoperable and the additional channel may be surveillance tested in bypass for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. For functions 1.e(1), 4.d(1), 4.d(2), and 6.d(1),
the inoperable channel and/or one additional channel may be surveillance tested with one channel in bypass and one channel in trip for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
This note is not intended to allow simultaneous testing of coincident channels on a routine basis.
D.1 Place channel in trip.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR In accordance with the RICT Program (continued) 3.3-20 Unit 1 - Amendment No. 135, 173, 179, Unit 2 - Amendment No. 135, 175, 181, 256 258
ESFAS Instrumentation 3.3.2 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 25 of 60 Tab_3!3u3r19.DOC 1106.1629 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME F.
One channel or train inoperable.
F.1 Restore channel or train to OPERABLE status.
48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> OR In accordance with the RICT Program G.
One train inoperable.
NOTE-----------------
One train may be bypassed for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for surveillance testing provided the other train is OPERABLE.
G.1 Restore train to OPERABLE status.
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> OR In accordance with the RICT Program H.
One train inoperable.
NOTE---------------
One train may be bypassed for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for surveillance testing provided the other train is OPERABLE.
H.1 Restore train to OPERABLE status.
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> OR In accordance with the RICT Program (continued) 3.3-21 Unit 1 - Amendment No. 135, 179, Unit 2 - Amendment No. 135, 181, 256 258
ESFAS Instrumentation 3.3.2 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 26 of 60 Tab_3!3u3r19.DOC 1106.1629 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME I.
One channel inoperable.
NOTE-----------------
The inoperable channel may be bypassed for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for surveillance testing of other channels.
I.1 Place channel in trip.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR In accordance with the RICT Program J.
One channel inoperable
NOTE-----------------
The inoperable channel and/or one additional channel may be surveillance tested with one channel in bypass and one channel in trip for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
This note is not intended to allow simultaneous testing of coincident channels on a routine basis.
J.1 Place channel in trip.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR In accordance with the RICT Program K.
One channel inoperable K.1.1 Place the channel in cut-out.
AND K.1.2 Return the inoperable channel to an OPERABLE status 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 48 hours OR In accordance with the RICT Program (continued) 3.3-22 Unit 1 - Amendment No. 135. 173, 179, Unit 2 - Amendment No. 135. 175, 181, 256 258
ACTIONS (continued)
CONDITION L.
One or more channels or trains inoperable.
M. One or more SG Water Level - Low Low Trip Time Delay channel(s) inoperable.
DIABLO CANYON - UNITS 1 & 2 REQUIRED ACTION L.1 Verify interlock is in required state for existing unit condition.
OR L.2.1 Be in MODE 3.
AND L.2.2 Be in MODE 4.
NOTE-----------------
The inoperable TTD channel (processor) and/or one additional TTD channel (processor) may be surveillance tested with the affected steam generator low-low water level channels for one TTD channel (processor) in bypass and the affected SG low-low water level channels for the other TTD channel (processor) in trip
- for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. This note is not intended to allow simultaneous testing of multiple TTD channels (processors) on a routine basis.
M.1 Set the Trip Time Delay to zero seconds.
OR M.2 Place the affected SG Water Level - Low Low channel(s) in trip.
ESFAS Instrumentation 3.3.2 COMPLETION TIME 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 7 hours 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> 72 hours 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR
NO TE----------
Not applicable when two or more required channels are inoperable.
In accordance with the RICT Program (continued) 3.3-23 Unit 1 - Amendment No. ~
..m, 4+9, Unit 2 -Amendment No.~. 47-a, 4-&i, 256 258
ESFAS Instrumentation 3.3.2 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 28 of 60 Tab_3!3u3r19.DOC 1106.1629 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME N.
One channel inoperable.
N.1 Restore channel to OPERABLE status.
OR 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> N.2 Declare the associated AFW pump or MSIV inoperable.
Immediately O.
One channel inoperable
NOTE-----------------
The inoperable channel may be surveillance tested in bypass for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, or with the inoperable channel in trip, one additional channel may be surveillance tested in bypass for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. This note is not intended to allow simultaneous testing of coincident channels on a routine basis.
O.1 Place channel in trip.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR In accordance with the RICT Program (continued) 3.3-24 Unit 1 - Amendment No. 135, 142, 173, 179, Unit 2 - Amendment No. 135, 142, 175, 181, 256 258
ESFAS Instrumentation 3.3.2 DIABLO CANYON - UNITS 1 & 2 Rev 19 Page 29 of 60 Tab_3!3u3r19.DOC 1106.1629 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME P.
One channel inoperable.
NOTE-----------------
The inoperable channel and one additional channel may be surveillance tested in bypass for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> only if any function 1.c channel associated with the inoperable channel is in trip. This note is not intended to allow simultaneous testing of coincident channels on a routine basis.
P.1 Place channel in bypass.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OR In accordance with the RICT Program Q.
Required Action and associated Completion Time of Conditions B or C not met.
Q.1 Be in MODE 3.
AND Q.2
NOTE-----------
LCO 3.0.4.a is not applicable when entering MODE 4.
Be in MODE 4.
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 12 hours R.
Required Action and associated Completion Time of Conditions D, F, G, or M not met.
R.1 Be in MODE 3.
AND R.2 Be in MODE 4.
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 12 hours S.
Required Action and associated Completion Time of Conditions H or J not met.
S.1 Be in MODE 3.
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> T.
Required Action and associated Completion Time of Condition I not met.
T.1 Be in MODE 2.
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> U.
Required Action and associated Completion Time of Conditions K, O, or P not met.
U.1 Be in MODE 3.
AND U.2 Be in MODE 5.
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 30 hours 3.3-24a Unit 1 - Amendment No. 135, 142, 173, 179, Unit 2 - Amendment No. 135, 142, 175, 181, 256 258
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 256 TO FACILITY OPERATING LICENSE NO. DPR-80 AND AMENDMENT NO. 258 TO FACILITY OPERATING LICENSE NO. DPR-82 PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT, UNITS 1 AND 2 DOCKET NOS. 50 275 AND 50 323
1.0 INTRODUCTION
By application dated December 24, 2024 (Reference 1), as supplemented by letter dated November 26, 2025 (Reference 2), Pacific Gas and Electric Company (PG&E, the licensee) submitted a license amendment request (LAR) for Diablo Canyon Nuclear Power Plant, Units 1 and 2 (Diablo Canyon). The proposed amendments would revise technical specification (TS) requirements TS 3.3.1, Reactor Trip System (RTS) Instrumentation and TS 3.3.2, Engineered Safety Feature Actuation System (ESFAS) Instrumentation.
The revision would permit the use of risk-informed completion times (RICTs) for actions to be taken when limiting conditions for operation (LCOs) are not met. The proposed changes are based on Technical Specifications Task Force (TSTF) Traveler TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF [Risk Informed TSTF] Initiative 4b, dated July 2, 2018 (Reference 3) (hereinafter referred to as TSTF-505). The U.S. Nuclear Regulatory Commission (NRC, the Commission) issued an approval for TSTF-505, including a model safety evaluation, on November 21, 2018 (Reference 4).
The licensee has proposed variations from the TS changes approved in TSTF-505, which are discussed in section 2.3 in the enclosure of the LAR and evaluated in section 3.0, below.
The NRC staff participated in a regulatory audit beginning in April 2025 to ascertain the information needed to support its review of the application and to develop requests for additional information if needed. Following the regulatory audit, PG&E submitted a supplement dated November 26, 2025.
The supplemental letter dated November 26, 2025, provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the NRC staffs original proposed no significant hazards consideration determination as published in the Federal Register on March 18, 2025 (90 FR 12568).
2.0 REGULATORY EVALUATION
Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of Production and Utilization Facilities, includes general provisions that establish the regulatory requirements a licensee must follow when submitting a license application. The NRC staff has identified the following sections within Chapter I of this title as relevant to the NRC staffs review of a licensees application to adopt TSTF-505:
10 CFR 50.36, Technical specifications, paragraph (c)(2), Limiting conditions for operation 10 CFR 50.55a, Codes and standards, paragraph (h), Protection and safety systems 10 CFR 50.65, Requirements for monitoring the effectiveness of maintenance at nuclear power plants (the Maintenance Rule) 10 CFR Part 20, Standard for Protection Against Radiation NRC regulatory guides (RGs) provide one way to ensure that the codified regulations continue to be met. The NRC staff considered the following guidance, along with industry guidance endorsed by the NRC, during its review of the proposed changes:
RG 1.200, Revision 2, An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities (Reference 5)
RG 1.174, Revision 2, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis (Reference 6)
RG 1.174, Revision 3, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis (Reference 7)
RG 1.177, Revision 2, Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications (Reference 8)
NUREG-1855, Revision 1, Guidance on the Treatment of Uncertainties Associated with PRAs [Probabilistic Risk Assessments] in Risk-Informed Decisionmaking (Reference 9)
NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR [Light-Water Reactor] Edition (SRP) chapter 16, section 16.1, Risk-Informed Decision Making: Technical Specifications (Reference 10) and chapter 19, section 19.2, Review of Risk Information Used to Support Permanent Plant-Specific Changes to the Licensing Basis: General Guidance (Reference 11)
The NRC staff also considered guidance developed by the Nuclear Energy Institute (NEI) that has been endorsed by the NRC: NEI Topical Report (TR) 06-09-A (NEI 06-09-A),
Risk-Informed Technical Specifications Initiative 4b, Risk-Managed Technical Specifications (RMTS) Guidelines (Reference 12).
The licensees submittal cites Revision 2 of RG 1.200. This regulatory guide has been updated to Revision 3 of RG 1.200 (Reference 13). The update does not include any technical changes that would impact the consistency with NEI 06-09-A, so the NRC staff finds the use of either revision to be acceptable in the implementation of TSTF-505.
2.1 Description of Risk-Informed Completion Time Program The TS LCOs are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When an LCO is not met, the licensee must shut down the reactor or follow any remedial or required action (e.g., testing, maintenance, or repair activity) permitted by the TSs until the condition can be met. The remedial actions (i.e., ACTIONS) associated with an LCO contain conditions that typically describe the ways in which the requirements of the LCO can fail to be met. Specified with each stated Condition are one or more Required Action(s) and associated Completion Time(s). The completion times are referred to as the front stops in the context of this safety evaluation. For certain conditions, the TSs require exiting the Mode of Applicability of an LCO (in other words, shut down the reactor).
The licensee has already implemented an approved RICT program. In this application the licensee is proposing no changes to that program, no changes to the design of the plant or any operating parameter, and no changes to the design basis. The effect of the proposed changes when implemented will allow additional TS completion times to vary, based on the risk significance of the given plant configuration (i.e., the equipment out of service at any given time), provided that the capability to perform the applicable safety function(s) is retained by the system so long as there are no further failures (e.g., one train of a two-train system is inoperable). These restrictions on inoperability of all required trains of a system ensure that consistency with the philosophy of defense in depth is maintained by following existing guidance when the capability to perform one or more technical specification safety functions is lost.
The RICT program uses plant-specific operating experience for component reliability and availability data. Thus, the allowances permitted by the RICT program reflect observed component performance in conjunction with component risk significance.
3.0 TECHNICAL EVALUATION
The NRC staff has already evaluated the licensees program for the implementation of risk-informed completion times. This review is documented in the safety evaluation for Diablo Canyon License Amendment Nos. 245 and 247 (Reference 14). For the review of the present LAR, the staff conducted an audit (Reference 15) during which the staff confirmed that the licensee has not deviated from the methodologies approved in these amendments. In the same audit, the staff confirmed that all changes to the PRA that required peer review have been addressed appropriately. Specifically, a focused-scope peer review of the fire PRA model was completed in April 2025, using the most recently endorsed version of the American Society of Mechanical Engineers/American Nuclear Society (ASME/ANS) PRA Standard ASME/ANS RA-Sa-2009 (Reference16).
Consequently, the NRC staff review was limited to the TSs that the licensee proposed to add to the scope of the RICT program, which were all within the scope of TSTF-505.
An acceptable approach for making risk-informed decisions about proposed changes to the TSs, including both permanent and temporary changes, is to demonstrate that the proposed licensing basis changes meet the five key principles provided in section C of RG 1.174, and the three-tiered approach outlined in section C of RG 1.177. These key principles and tiers are:
Principle 1:
The proposed licensing basis change meets the current regulations unless it is explicitly related to a requested exemption.
Principle 2:
The proposed licensing basis change is consistent with the defense-in-depth philosophy.
Principle 3:
The proposed licensing basis change maintains sufficient safety margins.
Principle 4:
When the proposed licensing basis change results in an increase in risk, the increase should be small and consistent with the intent of the Commissions policy statement on safety goals for the operations of nuclear power plants.
Tier 1: PRA Capability and Insights Tier 2: Avoidance of Risk-Significant Plant Configurations Tier 3: Risk-Informed Configuration Risk Management Principle 5:
The impact of the proposed licensing basis change should be monitored by using performance measures strategies.
3.1 Method of NRC Staff Review Each of the key principles and tiers are addressed in NEI 06-09-A and approved in the final model safety evaluation issued by the NRC for TSTF-505, Revision 2. The industry guidance provides a methodology for extending existing completion times and to thereby delay exiting the operational mode of applicability or taking Required Actions if risk is assessed and managed within the limits and programmatic requirements established by a RICT program. As stated at the beginning of this section, the NRC staffs evaluation of the licensees program, including acceptability of the PRA used in the program, is documented elsewhere. The NRC staffs evaluation of the licensees proposed use of additional RICTs against the key safety principles of RG 1.177 is discussed below.
3.1.1 Key Principle 1: Evaluation of Compliance with Current Regulations Paragraph 50.36(c)(2) of 10 CFR requires that LCOs are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When an LCO of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the TSs until the condition can be met.
The completion times in the current TSs were established using experiential data, risk insights, and engineering judgment. The RICT program provides the necessary administrative controls to permit extension of completion times and, thereby, delay reactor shutdown or Required Actions, if risk is assessed and managed appropriately within specified limits and programmatic requirements and the safety margins and defense in depth remains sufficient. The option to determine the extended completion time in accordance with the RICT program allows the
licensee to perform an integrated evaluation in accordance with the methodology prescribed in NEI 06-09-A and TS 5.5.20, Risk Informed Completion Time (RICT) Program. The RICT is limited to a maximum of 30 days (termed the back stop).
In attachment 4 and enclosure 1 of the LAR, as supplemented, the licensee provided a list of the TSs, associated LCOs, and Required Actions for the Completion Times that included modifications and variations from the approved TSTF-505. The modifications and variations consisted of proposed changes to the Required Actions and Completion Times. Furthermore, consistent with table 1 of TSTF-505, for Diablo Canyon TS 3.3.1 and TS 3.3.2 in attachment 1 of the LAR, the licensee included additional technical justification to demonstrate the acceptability for including these TSs in the RICT program. The NRC staff reviewed the proposed changes to the TSs, associated LCOs, Required Actions and Completion Times provided by the licensee for the additional scope to be added to the RICT program and concluded that the required performance levels of equipment specified in LCOs are not changed. Only the required Completion Times for the Required Actions are modified, such that 10 CFR 50.36(c)(2) will still be met. Based on the discussion provided above, the NRC staff finds that the LCOs, Required Actions, and Completion Times for these TSs meet the first key principle of RG 1.174 and RG 1.177.
3.1.2 Key Principle 2: Evaluation of Defense in Depth In RG 1.174, the NRC identified the following considerations used for evaluation of how the philosophy of defense in depth is maintained in the licensing basis:
Preserve a reasonable balance among the layers of defense.
Preserve adequate capability of design features without an overreliance on programmatic activities as compensatory measures.
Preserve system redundancy, independence, and diversity commensurate with the expected frequency and consequences of challenges to the system, including consideration of uncertainty.
Preserve adequate defense against potential common-cause failures (CCFs).
Maintain multiple fission product barriers.
Preserve sufficient defense against human errors.
Continue to meet the intent of the plants design criteria.
The licensee made a request to use the approved RICT program to extend the existing Completion Times for the respective TS LCOs prescribed in attachment 1 of the LAR, as supplemented. For these TS LCOs, the licensee provided a description and assessment of the redundancy and diversity for the proposed changes in the supplement dated November 26, 2025. The NRC staffs evaluation of the proposed changes for these LCOs assessed the Diablo Canyons redundant or diverse means to mitigate accidents to ensure consistency with the plant licensing basis requirements using the guidance prescribed in RG 1.174, Revision 2, RG 1.177, Revision 2, and TSTF-505, to ensure adequate defense in depth (for each of the functions) to
operate the facility in the proposed manner (i.e., that the changes are consistent with the defense-in-depth criteria).
In the enclosure of the LAR supplement dated November 26, 2025, the licensee provided information supporting the licensees evaluation of the redundancy, diversity, and defense in depth for each TS LCO and TS Required Action as it related to instrumentation and control (I&C) systems. The NRC confirmed that for the following TS LCOs, the above criteria were applicable except for the criteria for maintaining multiple fission product barriers.
TS 3.3.1, Reactor Trip System (RTS) Instrumentation TS 3.3.2, Engineered Safey Features Actuation System (ESFAS) Instrumentation For the TS LCOs specific to I&C, the NRC staff reviewed the specific trip logic arrangements, redundancy, backup systems, manual actions, and diverse trips specified for each of the protective safety functions and associated instrumentation as described in the associated sections of the Diablo Canyon Updated Final Safety Analysis Report (UFSAR) (Reference 17),
and as reflected in attachment 1 of the LAR for each I&C LCO listed above. The NRC staff verified that in accordance with the Diablo Canyon UFSAR and equipment and actions credited in attachment 1 of the LAR, in all applicable operating modes, the affected protective feature would perform its intended function by ensuring the ability to detect and mitigate the associated event or accident when the Completion Time of a channel is extended. Furthermore, the NRC staff concludes that there is sufficient redundancy, diversity, and defense in depth to protect against CCF and potential single failure for the Diablo Canyon instrumentation systems evaluated in the LAR, as supplemented, during a RICT. There is at least one diverse means specified by the licensee for initiating mitigating action for each accident event, thus providing defense in depth against a failure of instrumentation during the RICT for each TS LCO. The defense in depth specified by the licensee does not overly rely on manual actions as the diverse means; therefore, there is not over-reliance of programmatic activities as compensatory measures. Therefore, the NRC staff finds that the intent of the plants design criteria for the above TS LCOs related to I&C are maintained.
The NRC staff notes that while in a TS LCO condition, the redundancy of the function will be temporarily relaxed and, consequently, the system reliability will be degraded accordingly. The NRC staff examined the design information from the Diablo Canyon UFSAR and the risk-informed TS LCO conditions for the affected safety functions. Based on this information, the NRC staff confirmed that under any given design-basis accident evaluated in the Diablo Canyon UFSAR, the affected protective features maintain adequate defense in depth.
The NRC staff reviewed all TS LCOs proposed by the licensee in attachment 1 of the LAR, as supplemented, and the staff concludes that the proposed changes do not alter the ways in which the Diablo Canyon systems fail, do not introduce new CCF modes, and the system independence is maintained. With respect to the RICT program itself, all other findings remain the same as those documented in the safety evaluation for Diablo Canyon License Amendment Nos. 245 and 247.
Based on the above, the NRC staff finds that the licensees proposed changes are consistent with the NRC-endorsed guidance prescribed in NEI 06-09-A and satisfy the second key principle in RG 1.177, Revision 2. Additionally, the staff concludes that the changes are consistent with the defense-in-depth philosophy as described in RG 1.174, Revision 2.
3.1.3 Key Principle 3: Evaluation of Safety Margins Paragraph 50.55a(h) of 10 CFR requires, in part, that protection systems of nuclear power reactors of all types must meet the requirements specified in this paragraph. Section 2.2.2 of RG 1.177, Revision 2 states, in part, that sufficient safety margins are maintained when Codes and standards or alternatives approved for use by the NRC are met.
Safety analysis acceptance criteria in the final safety analysis report are met, or proposed revisions provide sufficient margin to account for analysis and data uncertainties.
The licensee is not proposing in this application to change any quality standard, material, or operating specification. In TS section 5.0, Administrative Controls, the RICT Program requires adherence to NEI 06-09-A. Condition 2 of this industry guidance stipulates that for the TS LCOs and action requirements to which the RMTS will apply, [the licensee will provide justification] with comparison of the TS functions to the PRA modeled functions of the SSCs
[structures, systems, and components] subject to those LCO actionsor an appropriate disposition or programmatic restriction will be provided. In the supplemental letter dated November 26, 2025, the licensee provided additional information regarding the application of a RICT for the TS Required Actions of TS 3.3.1 and TS 3.3.2.
Based on the acceptability of the Diablo Canyon RICT program and the information above, the NRC staff finds that the design-basis analyses for Diablo Canyon remains applicable and unchanged, sufficient safety margins would be maintained during the extended completion time, and the proposed changes to the TSs do not include any change in the standards applied or the safety analysis acceptance criteria. The NRC staff concludes that the proposed changes meet 10 CFR 50.55a(h), and therefore they satisfy the third key principle of RG 1.177, Revision 2.
3.1.4 Key Principle 4: Change in Risk Consistent with the Safety Goal Policy Statement The guidance in NEI 06-09-A provides a methodology for a licensee to evaluate and manage the risk impact of extensions to TS completion times. Permanent changes to the fixed TS completion times are typically evaluated by using the three-tiered approach described in SRP chapter 16, section 16.1, RG 1.177 and RG 1.174. This approach addresses the calculated change in risk as measured by the change in core damage frequency and large early release frequency, as well as the incremental conditional core damage probability and incremental conditional large early release probability; the use of compensatory measures to reduce risk; and the implementation of a configuration risk management program to identify risk-significant plant configurations.
The NRC staff evaluation of the licensees processes and methodologies is documented in the safety evaluation for Diablo Canyon License Amendment Nos. 245 and 247.
3.1.4.1 Tier 1: PRA Capability and Insights The first tier evaluates the impact of the proposed changes on plant operational risk. The Tier 1 review involves two aspects: (1) scope and acceptability of the PRA models and their application to the proposed changes, and (2) a review of the PRA results and insights described in the licensees application.
3.1.4.2 Tier 2: Avoidance of Risk-Significant Plant Configurations As prescribed in RG 1.177, Revision 2, the second tier evaluates the capability of the licensee to identify and avoid risk-significant plant configurations that could result if equipment, in addition to that associated with the proposed change, is taken out of service simultaneously or if other risk-significant operational factors, such as concurrent system or equipment testing, are also involved.
3.1.4.3 Tier 3: Risk-Informed Configuration Risk Management The third tier stipulates that a licensee should develop a program that ensures that the risk impact of out-of-service equipment is appropriately evaluated prior to performing any maintenance activity.
3.1.4.4 Key Principle 4: Conclusions The NRC staffs review of the licensees PRA, capability to avoid risk-significant plant configurations, and program to evaluate the risk associated with out-of-service equipment is documented in the safety evaluation for Diablo Canyon License Amendment Nos. 245 and 247.
The scope and acceptability of the PRA for use in the integrated decision-making process for the RICT program continues to be consistent with NEI 06-09-A, RG 1.174, Revision 2, and RG 1.177, Revision 2.
3.1.5 Key Principle 5: Performance Measurement StrategiesImplementation and Monitoring The guidance in RG 1.174, Revision 2 establishes the need for an implementation and monitoring program to ensure that extensions to technical specification completion times do not degrade operational safety over time and that no adverse degradation occurs due to unanticipated degradation or common-cause mechanisms.
The NRC staffs review of the licensees program implementation and monitoring program is documented in the safety evaluation for Diablo Canyon License Amendment Nos. 245 and 247.
3.2 Technical Evaluation Conclusion
The NRC staff has evaluated the proposed changes against each of the five key principles in RG 1.177, Revision 2 and RG 1.174, Revision 2, including the optional variations from the approved TSTF-505 discussed in section 3.1 of this safety evaluation. The staff concludes that the changes proposed by the licensee satisfy the key principles of risk-informed decision-making identified in RG 1.174 and RG 1.177. Therefore, the proposed changes to the technical specifications are acceptable to assure that the Commissions regulations continue to be met.
4.0 STATE CONSULTATION
In accordance with the Commissions regulations, on July 14, 2025, the California State official was notified of the proposed issuance of the amendments. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
These amendments change requirements with respect to the installation or use of a facility components located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts and no significant change in the types of any effluent 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 proposed finding that the amendments involve no significant hazards consideration, as published in the Federal Register on March 18, 2025 (90 FR 12568), and there has been no public comment on such finding. Accordingly, these 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.
6.0 CONCLUSION
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) there is reasonable assurance that such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
7.0 REFERENCES
1.
Brass, M. J., Pacific Gas and Electric Company, letter to U.S. Nuclear Regulatory Commission, License Amendment Request 24-05 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiavtive 4b for TS 3.3.1 and 3.3.2, dated December 24, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24359A002).
2.
Rogers, J. E., Pacific Gas and Electric Company, letter to U.S. Nuclear Regulatory Commission, Supplement to License Amendment Request 24-05 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b dated November 26, 2025 (ML25335A205).
3.
Technical Specifications Task Force, letter to U.S. Nuclear Regulatory Commission, TSTF Comments on Draft Safety Evaluation for Traveler TSTF-505, Provide Risk-Informed Extended Completion Times, and Submital of TSTF-505, Revision 2, dated July 2, 2018 (package ML18183A493).
4..
U.S. Nuclear Regulatory Commission, Final Revised Model Safety Evaluation of Traveler TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times -
RITSTF Initiative 4b, dated November 21, 2018 (package 18269A041).
5.
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Principal Contributors: Malcolm Patterson, NRR Norbert Carte, NRR Khadijah West, NRR Date: February 23, 2026
- by eConcurrence NRR-058 OFFICE NRR/DORL/LPL4/PM*
NRR/DORL/LPL4/LA*
NRR/DSS/STSB/BC NRR/DRA/APLA/BC (A)
NAME SLee PBlechman SMehta MGonzalez DATE 2/12/2026 2/19/2026 2/6/2026 2/2/2026 OFFICE NRR/DSS/SCPB/BC*
NRR/DSS/SNSB/BC NRR/DEX/EICB/BC (A)
NRR/DORL/LPL4/BC (A)*
NAME MValentin NDifrancesco SDarbali MMahoney DATE 2/12/2026 2/10/2026 2/2/2026 2/23/2026 OFFICE NRR/DORL/LPL4/PM*
NAME SLee DATE 2/23/2026