Nuc001-4

NUC-001-4— Nuclear Plant Interface Coordination

A. Introduction
1.

Title:

Nuclear Plant Interface Coordination

2.

Number:

NUC-001-4

3.

Purpose: This standard requires coordination between Nuclear Plant Generator
Operators and Transmission Entities for the purpose of ensuring nuclear plant safe
operation and shutdown.

4.

Applicability:
4.1. Functional Entities:
4.1.1 Nuclear Plant Generator Operators.
4.2. Transmission Entities shall mean all entities that are responsible for providing
services related to Nuclear Plant Interface Requirements (NPIRs). Such entities
may include one or more of the following:
4.2.1 Transmission Operators.
4.2.2 Transmission Owners.
4.2.3 Transmission Planners.
4.2.4 Transmission Service Providers.
4.2.5 Balancing Authorities.
4.2.6 Reliability Coordinators.
4.2.7 Planning Coordinators.
4.2.8 Distribution Providers.
4.2.9 Generator Owners.
4.2.10 Generator Operators.

5.

Effective Date: See Implementation Plan.

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NUC-001-4— Nuclear Plant Interface Coordination

B. Requirements and Measures
R1.

The Nuclear Plant Generator Operator shall provide the proposed NPIRs in writing to
the applicable Transmission Entities and shall verify receipt. [Violation Risk Factor:
Medium] [Time Horizon: Long-term Planning ]

M1. The Nuclear Plant Generator Operator shall, upon request of the Compliance
Enforcement Authority, provide a copy of the transmittal and receipt of transmittal of
the proposed NPIRs to the responsible Transmission Entities.
R2.

The Nuclear Plant Generator Operator and the applicable Transmission Entities shall
have in effect one or more Agreements1 that include mutually agreed to NPIRs and
document how the Nuclear Plant Generator Operator and the applicable Transmission
Entities shall address and implement these NPIRs. [Violation Risk Factor: Medium]
[Time Horizon: Long-term Planning ]

M2. The Nuclear Plant Generator Operator and each Transmission Entity shall each have a
copy of the currently effective Agreement(s) which document how the Nuclear Plant
Generator Operator and the applicable Transmission Entities address and implement
the NPIRs available for inspection upon request of the Compliance Enforcement
Authority.
R3.

Per the Agreements developed in accordance with this standard, the applicable
Transmission Entities shall incorporate the NPIRs into their planning analyses of the
electric system and shall communicate the results of these analyses to the Nuclear
Plant Generator Operator.: [Violation Risk Factor: Medium] [Time Horizon: Long-term
Planning]

M3. Each Transmission Entity responsible for planning analyses in accordance with the
Agreement shall, upon request of the Compliance Enforcement Authority, provide a
copy of the planning analyses results transmitted to the Nuclear Plant Generator
Operator, showing incorporation of the NPIRs. The Compliance Enforcement
Authority shall refer to the Agreements developed in accordance with this standard
for specific requirements.
R4.

Per the Agreements developed in accordance with this standard, the applicable
Transmission Entities shall [Violation Risk Factor: High] [Time Horizon: Operations
Planning and Real-time Operations]
4.1. Incorporate the NPIRs into their operating analyses of the electric system.
4.2. Operate the electric system to meet the NPIRs.

1

Agreements may include mutually agreed upon procedures or protocols in effect between entities or between departments of
a vertically integrated system.

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NUC-001-4— Nuclear Plant Interface Coordination

4.3. Inform the Nuclear Plant Generator Operator when the ability to assess the
operation of the electric system affecting NPIRs is lost.
M4. Each Transmission Entity responsible for operating the electric system in accordance
with the Agreement shall demonstrate or provide evidence of the following, upon
request of the Compliance Enforcement Authority:

R5.



The NPIRs have been incorporated into the current operating analysis of the
electric system. (Requirement 4.1)



The electric system was operated to meet the NPIRs. (Requirement 4.2)



The Transmission Entity informed the Nuclear Plant Generator Operator when it
became aware it lost the capability to assess the operation of the electric system
affecting the NPIRs

Per the Agreements developed in accordance with this standard, the Nuclear Plant
Generator Operator shall operate the nuclear plant to meet the NPIRs. [Violation Risk
Factor: High] [Time Horizon: Operations Planning and Real-time Operations ]

M5. The Nuclear Plant Generator Operator shall, upon request of the Compliance
Enforcement Authority, demonstrate or provide evidence that the nuclear power
plant is being operated consistent with the NPIRs.
R6.

Per the Agreements developed in accordance with this standard, the applicable
Transmission Entities and the Nuclear Plant Generator Operator shall coordinate
outages and maintenance activities which affect the NPIRs. [Violation Risk Factor:
Medium] [Time Horizon: Operations Planning]

M6. The Transmission Entities and Nuclear Plant Generator Operator shall, upon request
of the Compliance Enforcement Authority, provide evidence of the coordination
between the Transmission Entities and the Nuclear Plant Generator Operator
regarding outages and maintenance activities which affect the NPIRs.
R7.

Per the Agreements developed in accordance with this standard, the Nuclear Plant
Generator Operator shall inform the applicable Transmission Entities of actual or
proposed changes to nuclear plant design (e.g., protective relay setpoints),
configuration, operations, limits, or capabilities that may impact the ability of the
electric system to meet the NPIRs. [Violation Risk Factor: High] [Time Horizon: Longterm Planning]

M7. The Nuclear Plant Generator Operator shall provide evidence that it informed the
applicable Transmission Entities of changes to nuclear plant design (e.g., protective
relay setpoints), configuration, operations, limits, or capabilities that may impact the
ability of the Transmission Entities to meet the NPIRs.

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R8.

Per the Agreements developed in accordance with this standard, the applicable
Transmission Entities shall inform the Nuclear Plant Generator Operator of actual or
proposed changes to electric system design (e.g., protective relay setpoints),
configuration, operations, limits, or capabilities that may impact the ability of the
electric system to meet the NPIRs. [Violation Risk Factor: High] [Time Horizon: Longterm Planning]

M8. The Transmission Entities shall each provide evidence that the entities informed the
Nuclear Plant Generator Operator of changes to electric system design (e.g.,
protective relay setpoints), configuration, operations, limits, or capabilities that may
impact the ability of the Nuclear Plant Generator Operator to meet the NPIRs.
R9.

The Nuclear Plant Generator Operator and the applicable Transmission Entities shall
include the following elements in aggregate within the Agreement(s) identified in R2.


Where multiple Agreements with a single Transmission Entity are put into effect,
the R9 elements must be addressed in aggregate within the Agreements;
however, each Agreement does not have to contain each element. The Nuclear
Plant Generator Operator and the Transmission Entity are responsible for ensuring
all the R9 elements are addressed in aggregate within the Agreements.



Where Agreements with multiple Transmission Entities are required, the Nuclear
Plant Generator Operator is responsible for ensuring all the R9 elements are
addressed in aggregate within the Agreements with the Transmission Entities. The
Agreements with each Transmission Entity do not have to contain each element;
however, the Agreements with the multiple Transmission Entities, in the
aggregate, must address all R9 elements. For each Agreement(s), the Nuclear
Plant Generator Operator and the Transmission Entity are responsible to ensure
the Agreement(s) contain(s) the elements of R9 applicable to that Transmission
Entity. : [Violation Risk Factor: Medium] [Time Horizon: Long-term Planning]

9.1. Retired. [Note: Part 9.1 was retired under the Paragraph 81 project. The NUC SDT
proposes to leave this Part blank to avoid renumbering Requirement parts that
would impact existing agreements throughout the industry.]
9.2. Technical requirements and analysis:
9.2.1. Identification of parameters, limits, configurations, and operating
scenarios included in the NPIRs and, as applicable, procedures for
providing any specific data not provided within the Agreement.
9.2.2. Identification of facilities, components, and configuration restrictions that
are essential for meeting the NPIRs.
9.2.3. Types of planning and operational analyses performed specifically to
support the NPIRs, including the frequency of studies and types of
Contingencies and scenarios required.

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9.3. Operations and maintenance coordination
9.3.1. Designation of ownership of electrical facilities at the interface between
the electric system and the nuclear plant and responsibilities for
operational control coordination and maintenance of these facilities.
9.3.2. Identification of any maintenance requirements for equipment not
owned or controlled by the Nuclear Plant Generator Operator that are
necessary to meet the NPIRs.
9.3.3. Coordination of testing, calibration and maintenance of on-site and offsite power supply systems and related components.
9.3.4. Provisions to address mitigating actions needed to avoid violating NPIRs
and to address periods when responsible Transmission Entity loses the
ability to assess the capability of the electric system to meet the NPIRs.
These provisions shall include responsibility to notify the Nuclear Plant
Generator Operator within a specified time frame.
9.3.5. Provision for considering, within the restoration process, the
requirements and urgency of a nuclear plant that has lost all off-site and
on-site AC power.
9.3.6. Coordination of physical and cyber security protection at the nuclear
plant interface to ensure each asset is covered under at least one entity’s
plan.
9.3.7. Coordination of the NPIRs with transmission system Remedial Action
Schemes and any programs that reduce or shed load based on
underfrequency or undervoltage.
9.4. Communications and training Administrative elements:
9.4.1. Provisions for communications affecting the NPIRs between the Nuclear
Plant Generator Operator and Transmission Entities, including
communications protocols, notification time requirements, and
definitions of applicable unique terms.
9.4.2. Provisions for coordination during an off-normal or emergency event
affecting the NPIRs, including the need to provide timely information
explaining the event, an estimate of when the system will be returned to
a normal state, and the actual time the system is returned to normal.
9.4.3. Provisions for coordinating investigations of causes of unplanned events
affecting the NPIRs and developing solutions to minimize future risk of
such events.
9.4.4. Provisions for supplying information necessary to report to government
agencies, as related to NPIRs.
9.4.5. Provisions for personnel training, as related to NPIRs.

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M9. The Nuclear Plant Generator Operator shall have a copy of the Agreement(s)
addressing the elements in Requirement 9 available for inspection upon request of the
Compliance Enforcement Authority. Each Transmission Entity shall have a copy of the
Agreement(s) addressing the elements in Requirement 9 for which it is responsible available
for inspection upon request of the Compliance Enforcement Authority.

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C. Compliance
1.

Compliance Monitoring Process
1.1. Compliance Enforcement Authority
Regional Entity
1.2. Compliance Monitoring and Assessment Processes:
Compliance Audits
Self-Certifications
Spot Checking
Compliance Violation Investigations
Self-Reporting
Complaints Text
1.3. Data Retention
The Responsible Entity shall keep data or evidence to show compliance as
identified below unless directed by its Compliance Enforcement Authority to
retain specific evidence for a longer period of time as part of an investigation:


For Measure 1, the Nuclear Plant Generator Operator shall keep its latest
transmittals and receipts.



For Measure 2, the Nuclear Plant Generator Operator and each
Transmission Entity shall have its current, in-force Agreement.



For Measure 3, the Transmission Entity shall have the latest planning
analysis results.



For Measures 4, 6 and 8, the Transmission Entity shall keep evidence for
two years plus current.



For Measures 5, 6 and 7, the Nuclear Plant Generator Operator shall keep
evidence for two years plus current.

If a Responsible Entity is found non-compliant it shall keep information related to
the noncompliance until found compliant.
The Compliance Enforcement Authority shall keep the last audit records and all
requested and submitted subsequent audit records.
1.4. Additional Compliance Information
None

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NUC-001-4— Nuclear Plant Interface Coordination

Table of Compliance Elements
R#

Time
Horizon

VRF

Violation Severity Levels
Lower VSL

R1

R2

Medium The Nuclear Plant
Generator Operator
provided the NPIRs to
the applicable entities
but did not verify
receipt.

Medium N/A

Moderate VSL

The Nuclear Plant
Generator Operator
did not provide the
proposed NPIR to one
of the applicable
entities unless there
was only one entity.

N/A

High VSL

Severe VSL

The Nuclear Plant
Generator Operator
did not provide the
proposed NPIRs to
two of the applicable
entities unless there
were only two
entities.

The Nuclear Plant
Generator Operator
did not provide the
proposed NPIRs to
more than two of
applicable entities.

N/A

The Nuclear Plant
Generator Operator or
the applicable
Transmission Entity
does not have in effect
one or more
agreements that
include mutually
agreed to NPIRs and

OR
For a particular
nuclear power plant, if
the number of
possible applicable
transmission entities is
equal to the number
of applicable
transmission entities
not provided NPIRs

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R#

Time
Horizon

VRF

Violation Severity Levels
Lower VSL

Moderate VSL

High VSL

Severe VSL

document the
implementation of the
NPIRs.
R3

Medium N/A

The responsible entity
incorporated the
NPIRs into its planning
analyses but did not
communicate the
results to the Nuclear
Plant Generator
Operator.

N/A

The responsible entity
did not incorporate
the NPIRs into its
planning analyses of
the electric system.

R4

High

N/A

The responsible entity
did not comply with
Requirement R4, Part
4.3.

The responsible entity
did not comply with
Requirement R4, Part
R4.1.

The responsible entity
did not comply with
Requirement R4, Part
R4.2.

R5

High

N/A

N/A

N/A

The Nuclear Plant
Generator Operator
failed to operate per
the NPIRs developed
in accordance with
this standard.

R6

Medium N/A

The Nuclear Plant
Generator Operator or
Transmission Entity
failed to provide

The Nuclear Plant
N/A
Generator Operator or
Transmission Entity
failed to coordinate

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R#

Time
Horizon

VRF

Violation Severity Levels
Lower VSL

Moderate VSL

outage or
maintenance
schedules to the
appropriate parties as
described in the
agreement or on a
time period consistent
with the agreements.

High VSL

Severe VSL

one or more outages
or maintenance
activities in
accordance the
requirements of the
agreements.

R7

High

The Nuclear Plant
N/A
Generator Operator
did not inform the
applicable
Transmission Entities
of proposed changes
to nuclear plant design
(e.g. protective relay
setpoints),
configuration,
operations, limits, or
capabilities that may
impact the ability of
the electric system to
meet the NPIRs.

The Nuclear Plant
Generator Operator
did not inform the
applicable
Transmission Entities
of actual changes to
nuclear plant design
(e.g. protective relay
setpoints),
configuration,
operations, limits, or
capabilities that may
impact the ability of
the electric system to
meet the NPIRs.

The Nuclear Plant
Generator Operator
did not inform the
applicable
Transmission Entities
of actual changes to
nuclear plant design
(e.g., protective relay
setpoints),
configuration,
operations, limits or
capabilities that
directly impact the
ability of the electric
system to meet the
NPIRs.

R8

High

The applicable
Transmission Entities
did not inform the

The applicable
Transmission Entities
did not inform the

The applicable
Transmission Entities
did not inform the

N/A

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R#

Time
Horizon

VRF

Violation Severity Levels
Lower VSL

Moderate VSL

Nuclear Plant
Generator Operator of
proposed changes to
transmission system
design, configuration
(e.g. protective relay
setpoints), operations,
limits, or capabilities
that may impact the
ability of the electric
system to meet the
NPIRs.
R9

Medium

The Agreement(s)
identified in R2.
between the Nuclear
Plant Generator
Operator and the
applicable
Transmission Entity
failed to include up to
20% of the combined
sub-components in
Requirement R9 Parts
9.2, 9.3 and 9.4
applicable to that
entity.

High VSL

Severe VSL

Nuclear Plant
Generator Operator of
actual changes to
transmission system
design (e.g. protective
relay setpoints),
configuration,
operations, limits, or
capabilities that may
impact the ability of
the electric system to
meet the NPIRs.

Nuclear Plant
Generator Operator of
actual changes to
transmission system
design (e.g. protective
relay setpoints),
configuration,
operations, limits, or
capabilities that
directly impacts the
ability of the electric
system to meet the
NPIRs.

The Agreement(s)
identified in R2.
between the Nuclear
Plant Generator
Operator and the
applicable
Transmission Entity
failed to include
greater than 20%, but
less than 40% of the
combined subcomponents in
Requirement R9 Parts
9.2, 9.3 and 9.4

The Agreement(s)
identified in R2.
between the Nuclear
Plant Generator
Operator and the
applicable
Transmission Entity
failed to include 40%
or more of the
combined subcomponents in
Requirement R9 Parts
9.2, 9.3 and 9.4

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R#

Time
Horizon

VRF

Violation Severity Levels
Lower VSL

Moderate VSL

High VSL

applicable to the
entity.

Severe VSL

applicable to the
entity.

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NUC-001-4— Nuclear Plant Interface Coordination

D. Regional Variances
The design basis for Canadian (CANDU) nuclear power plants (NPPs) does not result in the
same licensing requirements as U.S. NPPs. Nuclear Regulatory Commission (NRC) design
criteria specifies that in addition to emergency on-site electrical power, electrical power
from the electric network also be provided to permit safe shutdown. There are no
equivalent Canadian Regulatory requirements for electrical power from the electric network
to be provided to permit safe shutdown. Therefore the definition of Nuclear Plant Licensing
Requirements (NPLR) for Canadian CANDU NPPs will be as follows:
Canadian Nuclear Plant Licensing Requirements (CNPLR) are requirements included in the
design basis of the nuclear plant and are statutorily mandated for the operation of the
plant; when used in this standard, NPLR shall mean nuclear power plant licensing
requirements for avoiding preventable challenges to nuclear safety as a result of an electric
system disturbance, transient, or condition.

E. Interpretations
None

F. Associated Documents
None

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Version History
Version

Date

Action

Change Tracking

1

May 2, 2007

Approved by Board of
Trustees

2

August 5, 2009

Adopted by Board of Trustees Revised. Modifications
for Order 716 to
Requirement R9.3.5 and
footnote 1;
modifications to bring
compliance elements
into conformance with
the latest version of the
ERO Rules of Procedure.

2

January 22, 2010

Approved by FERC on January
21, 2010. Added Effective
Date

2

February 7, 2013

R9.1, R9.1.1, R9.1.2, R9.1.3,
and R9.1.4 and associated
elements approved by NERC
Board of Trustees for
retirement as part of the
Paragraph 81 project (Project
2013-02) pending applicable
regulatory approval.

2

November 21, 2013 R9.1, R9.1.1, R9.1.2, R9.1.3,
and R9.1.4 and associated
elements approved by FERC
for retirement as part of the
Paragraph 81 project (Project
2013-02)

2.1

April 11, 2012

2.1

September 9, 2013

New

Update

Errata approved by the
Errata associated with
Standards Committee;
Project 2007-17
(Capitalized “Protection
System” in accordance with
Implementation Plan for
Project 2007-17 approval of
revised definition of
“Protection System”)
Informational filing submitted
to reflect the revised

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NUC-001-4— Nuclear Plant Interface Coordination

definition of Protection
System in accordance with
the Implementation Plan for
the revised term.
3

March 2014

Modifications to implement
the recommendations of the
five-year review of NUC-001,
which was accepted by the
Standards Committee on
October 17, 2013.

3

August 14, 2014

Adopted by the NERC Board
of Trustees

3

November 4, 2014

FERC letter order issued
approving NUC-001-3

4

February 6, 2020

Adopted by NERC Board of
Trustees

Revision

Revisions under Project
2017-07

Rationale
During development of this standard, text boxes were embedded within the standard to explain
the rationale for various parts of the standard. Upon BOT approval, the text from the rationale
text boxes was moved to this section.
Rationale for R5:
The NUC FYRT recommended R5 be revised for consistency with R4 and to clarify that nuclear
plants must be operated to meet the Nuclear Plant Interface Requirements.
Rationale for R7 and R8:
The NUC FYRT recommended deleting “Protection Systems” in Requirements R7 and R8 since it
is a subset of the "nuclear plant design" and "electric system design" elements currently
contained in R7 and R8 respectively; and adding a parenthetical clause (e.g. protective
setpoints) to R7 following "nuclear plant design" and parenthetical clause (e.g. relay setpoints)
to R8 following "electric system design."
Rationale for R9:
The NUC FYRT recommended that R9 be revised to clarify that all agreements do not have to
discuss each of the elements in R9, but that the sum total of the agreements need to address
the elements. In addition, for clarity in Part 9.4.1, the NUC FYRT recommended that "affecting
the NPIRs" be inserted following "Provisions for communications" and "applicable unique" be
inserted following ""definitions of."

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Rationale for R9.3.7:
The term “Special Protection Systems” (SPS) was replaced with “Remedial Action Schemes”
(RAS) in order to align with other current NERC standards development work in Project 201005.2: Special Protection Systems. Project 2010-05.2 has proposed to replace SPS with RAS
throughout all of the NERC Standards in order to move to the use of a single term. RAS and SPS
have the same definition in the NERC Glossary of Terms.

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