ML18163A386
| ML18163A386 | |
| Person / Time | |
|---|---|
| Issue date: | 06/13/2018 |
| From: | NRC/NRR/DLP/PLPB |
| To: | |
| Golla J | |
| References | |
| Download: ML18163A386 (3) | |
Text
NRC ISG-06 Revision 2 Tabletop Material June 13-14, 2018 The examples provided from a Safety Function Summary Table, below, illustrate how the plant and I&C system safety analysis design basis information can be summarized to support vendor design, V&V, oversight, and regulatory review activities. The summary information serves to:
facilitate interdisciplinary technical reviews by the licensee (e.g., safety analysis and I&C departments) to ensure plant safety analyses are correctly implemented in the I&C design, facilitate communication of key design basis information to the I&C vendor and support vendor oversight activities, support V&V activities to ensure key design basis requirements are correctly implemented, and facilitate regulatory reviews of the plant modification.
The example table also illustrates how the information can be presented to support the regulatory review of the modification. Four examples are presented show how change information can be presented for easy identification.
The first example presents a case where no changes are made to the BWR design basis as part of the plant I&C modernization modification. The new I&C equipment would simply implement the existing design-basis requirements on new equipment.
The second example illustrates a similar case where the design basis is based on engineering judgement rather than explicitly linked to a FSAR AOO or PA analysis.
The third example presents a case where limited changes are made to the design basis as part of the plant I&C modernization modification. Examples might be a change to an analytical limit or response time. The third example shown in the table illustrates a case where an architecture change was made to the ESFAS design to add a redundant 2-out-of-three-3 logic structure to the I&C system design. The change to the design basis information is shown in bold italics for easy identification. This change is similar to a change made for the Oconee design.
The fourth example presents a case where a new safety function is added to the design as part of a plant I&C modernization modification. The changes to the design basis information are shown in bold italics for easy identification. This change is similar to a change made for the Hope Creek Power Range Neutron Monitoring System design. The example only shows the new function added (item f) for brevity.
NRC ISG-06 Revision 2 Tabletop Material June 13-14, 2018 Examples from the Safety Function Summary Table for Section 4.2.1.1 FSAR Event (AOO/PA)
Credited Trip/Actuation Signals Variable(s)
Range Nominal (100% RTP)
Analytical Limit Number of Channels Actuation Logic Automated Protection Function Interlock/Permissive/
Override Condition for Interlock/Permissive/
Override Function Response Time Assumed in FSAR Event Analysis (seconds)
EXAMPLE 1 Rod Withdrawal
- Accident, the Rod Ejection
- Accident, and the Steam Line Break Accident Nuclear Overpower -
High Setpoint Power Range Neutron Flux 0 - 125%
RTP 100%
109% RTP 4
2oo4 Reactor Trip Power Range Linear Power Permissive 2oo4 Automatically switch to bypass Nuclear Overpower -
High Setpoint and enable Nuclear Overpower -
Low Setpoint 2
EXAMPLE 2 None Nuclear Overpower -
Low Setpoint Power Range Neutron Flux 0 - 125%
RTP 100%
15% RTP 4
2oo4 Reactor Trip Power Range Linear Power Permissive 3oo4 Automatically enable Nuclear Overpower -
High Setpoint and allow manual bypass of Nuclear Overpower -
Low Setpoint None
NRC ISG-06 Revision 2 Tabletop Material June 13-14, 2018 FSAR Event (AOO/PA)
Credited Trip/Actuation Signals Variable(s)
Range Nominal (100% RTP)
Analytical Limit Number of Channels Actuation Logic Automated Protection Function Interlock/Permissive/
Override Condition for Interlock/Permissive/
Override Function Response Time Assumed in FSAR Event Analysis (seconds)
EXAMPLE 3 Loss of Coolant Accident RCS Pressure -
Low Setpoint RCS Pressure 0 - 2500 psi 2250 psi 1800 psi 3
Redundant 2oo3 ECCS Initiation RCS Pressure Permissive 2oo4 Allow manual bypass of RCS Pressure
- Low Setpoint 25 3oo4 Automatically enable RCS Pressure -
Low Setpoint EXAMPLE 4 Anticipated Thermal-Hydraulic Power Oscillations Average Power Range Monitor
2oo4 Reactor Trip OPRM Armed Permissive 2oo4 Automatically enable OPRM 2
Note: Changes associated with license amendment request shown in bold italics