Technical Specifications for Generic Letter 83-28, Item 4.3 (Generic Letter No. 85-09)
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C. 20555
May 23, 1985
TO ALL WESTINGHOUSE PRESSURIZED WATER REACTOR LICENSEES AND APPLICANTS
Gentlemen:
SUBJECT: TECHNICAL SPECIFICATIONS FOR GENERIC LETTER 83-28, ITEM 4.3
(Generic Letter 85-09)
Reference: "Safety Evaluation, Generic Westinghouse Modifications for
Reactor Trip System Automatic Actuation Using Shunt Coil Trip
Attachments;" August 10, 1983, Letter from Darrell G.
Eisenhut, Director, Division of Licensing to J. J. Sheppard,
Chairman, Westinghouse Owners Group.
Item 4.3 of Generic Letter 83-28, "Required Actions Based on Generic
Implications of Salem ATWS Events," established the requirement for the
automatic actuation of the shunt trip attachment for Westinghouse plants.
Also, licensees are to submit any needed Technical Specification change
requests as goon as practical following staff review and approval of the
modified design.
In the staff's evaluation of the Westinghouse generic design modifications
(reference), the staff concluded that Technical Specification changes should
c be proposed by licensees to explicitly require independent testing of the
undervoltage and shunt trip attachments during power operation and
independent testing of the control room manual switch contacts during each
refueling outage. The staff concluded that these tests are necessary to
ensure reliable reactor trip breaker operation. In the staff's review of the
plant-specific responses to the generic letter, some licensees have
indicated that changes to the Technical Specifications are not required for
their plants. In such cases, the staff has found that the existing Technical
Specifications do not address the concerns mentioned above and the staff
has. indicated that the required Technical Specification changes should be
submitted.
Therefore, licensees are requested to submit proposed Technical
Specification changes which are responsive to the guidance noted in the
enclosure. The enclosed guidance will be used to revise the Standard
Technical Specifications for Westinghouse plants, and it will be used by the
staff as a basis to review changes to Technical Specifications submitted by
licensees and for the review of proposed Technical Specifications for
operating license applications.
For plants which have implemented the shunt trip modifications, a schedule
for submittal of proposed Technical Specification changes should be
established through discussions with the individual Project Manager for each
facility. In addition, discussions with the individual Project Managers
should establish a schedule for plants which have not implemented the shunt
trip modifications. Proposed Technical Specifications should be submitted as
soon as practical Am following staff review and approval of the modified
design. For operating license applicants, proposed Technical Specifications
should include requirements which are responsive to the enclosed guidance.
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This request for information was approved by the Office of Management and
Budget under clearance number 3150-0011 which expires April 30, 1985. Should
you have any questions, the staff contact is Rudy Karsch. Mr. Karsch can be
reached on (301) 492-8563.
Hugh L. Thompson, Jr., Director
Division of Licensing
Enclosure:
Sample Technical Specifications
List, of Generic Letters
ENCLOSURE
TECHNICAL SPECIFICATION CHANGES
FOR REACTOR TRIP BREAKERS
(WESTINGHOUSE PLANTS)
BACKGROUND
As a consequence of the Salem ATWS event, Item 4.3 of Generic Letter 83-28
established the requirement for the automatic actuation of the shunt trip
attachment for reactor trip breakers. Further, licensees are to submit any
needed technical specification change requests prior to declaring the
modified system operable. A number of the responses from operating reactors
have indicated that no technical specification changes are required.
The staff has reviewed the guidance provided in the Standard Technical
Specifications (STS) for Westinghouse Plants, NUREG-0452, and finds that
additional clarification of both the limiting conditions of operation and
surveillance requirements are appropriate as a result of the staff's
evaluation of design modifications to include automatic actuation of the
shunt trip attachments. The STS for Westinghouse plants will be revised to
include the changes noted herein. Pending formal revision of the STS, this
document provides guidance to licensees and operating license applicants on
appropriate technical specifications in response to Item 4.3 of the Generic
Letter.
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DISCUSSION
The operability requirements for the reactor trip breakers are specified in
Table 3.3-1 of the STS. The specification states that both reactor trip
breakers shall be operable in Modes 1 and 2. In addition, both breakers are
to be operable when in Modes 3, 4, and 5 if the breakers are in the closed
position and the control rod drive system is capable of rod withdrawal. The
action statements for an inoperable breaker require that the plant be in at
least hot standby within six hours for Modes 1 and 2, and that the breaker
be restored to operable status in 48 hours or opened in the next hour when
operating in Modes 3, 4, or 5.
With the addition of the automatic actuation of the shunt trip attachment
(STA), diverse features exist to effect a reactor trip for each breaker. If
one of these diverse trip features is inoperable, a decision would have to
be made with regard to the operability status of the reactor trip breaker.
The definition of OPERABLE-OPERABILITY in Section 1.0 of the STS states that
a component shall be operable or have operability when it is capable of
performing its safety function. Since either trip feature being operable
would initiate a reactor trip on demand, it would be overly conservative to
treat a breaker as inoperable if one of these diverse trip features were
inoperable. However, on the other hand, the reliability of the reactor trip
system would be reduced if each diverse trip feature is not maintained in an
operable status.
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The reactor trip breaker surveillance test should independently verify the
operability of the shunt and undervoltage trip features of the reactor trip
breakers as part of a single sequential test procedure. Therefore, the
surveillance test which identifies a failure of one diverse trip feature
also confirms the operability of the other trip feature. As a consequence,
there is a high degree of confidence that the operable trip feature would be
capable of initiating a reactor trip in the next 48 hours. Accordingly, an
additional action statement will be included in the STS for the reactor trip
breakers to permit continued plant operation for up to 48 hours with one of
the diverse trip features inoperable before further action needs to be
taken. The additional action statement is as follows:
ACTION - With one of the diverse trip features (undervoltage or shunt
trip attachment) inoperable, restore it to OPERABLE status within 48
hours or declare the breaker inoperable and apply ACTION 12. The
breaker shall not be bypassed while one of the diverse trip features is
inoperable except for the time required for performing maintenance to
restore the breaker to OPERABLE status.
The Westinghouse generic design modification includes test features which
permit the independent testing to verify the operability of the shunt and
undervoltage trip attachments. Some licensees have proposed changes to the
surveillance requirements specified in Table 4.3-1 to specifically note the
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requirement for independent testing of the diverse trip features. As noted
above, operability as applied to the diverse trip features of breakers may
have different degrees of safety significance. In order to be consistent
with the intent of the test features provided, the following notation will
be included in Table 4.3-1 for reactor trip breakers:
"The TRIP ACTUATING DEVICE OPERATIONAL TEST shall independently verify
the OPERABILITY of the undervoltage and shunt trip attachments of the
Reactor Trip Breakers."
In the evaluation of Westinghouse generic design, the staff noted that the
procedures for testing the breakers did not include verification of the
operability of the control room manual reactor trip switch contacts and
wiring in the manual initiation circuits. However, it was noted that a
procedure for this test was being developed by Westinghouse Owners Group. In
its conclusions, the staff noted that licensees should propose technical
specification changes to explicitly provide for periodic independent testing
of the control room manual switch contacts during each refueling outage.
Table 4.3-1 of the STS specifies that the manual reactor trip function be
tested at least once per 18 months. However, unlike the modification for
automatic actuation of the shunt trip attachments, test features are not
incorporated in the design for most plants to facilitate the independent
testing of the shunt and undervoltage trip circuits for the manual reactor
trip function. As noted in the staff's evaluation of the Westinghouse
generic
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design, the surveillance tests for the manual reactor trip may be performed
in a manner to verify the operability of the reactor trip switch contacts
and wiring to the circuit breakers. This test may be performed by voltage
measurements at terminal blocks of the reactor trip breakers and it is not
necessary to physically trip the breakers during this test.
Two precautions are applicable if this method of testing is implemented. One
is that the "Block auto shunt trip" switch would have to be used to preclude
sensing the application of power to the shunt trip coil via the automatic
shunt trip feature. The second is that with the breaker in a tripped
condition, voltage would be measured across the combination of the shunt
trip coil and series breaker "a" auxiliary contact due to the presence of
the breaker closed position status light located in parallel with the
normally open manual reactor trip switch contacts. If voltage measurements
are used for this test, the indicating light would have to be removed or
other appropriate action taken such that measurements would not be
ambiguous.
Therefore, the following notation will be added to Table 4.3-1 of the STS to
be consistent with the intent of the staff's evaluation of the manual
reactor trip function:
"The TRIP ACTUATING DEVICE OPERATIONAL TEST shall independently verify
the OPERABILITY of the shunt and undervoltage trip circuits for the
Manual Reactor Trip Function."
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The current STS do not address surveillance requirements for the reactor
trip bypass breakers. In the evaluation of the Westinghouse generic design
modifications, the staff noted that it would require that the operability of
the bypass breakers be verified prior to it being placed into service. In
response to this requirement, some licensees have noted that the bypass
breakers are maintained in a racked out position during normal operation and
the required testing is performed by moving the breaker to the test
position. In the test position, the operability of the shunt trip attachment
is verified via the local shunt trip switch at the breaker. Following this
test, the breaker is racked into the operate position and closed to pe mit
testing of its associated reactor trip breaker. Since the operation of the
undervoltage trip attachment for the bypass breakers are actuated by the
opposite train of the protection systems, it has been proposed to test this
feature during refueling outages. Finally it was noted that the testing of
the manual reactor trip function which is performed during refueling outages
includes operation of the bypass breakers to verify the operability of the
manual trip circuit(s).
The staff conclusion is that the above proposed methods for testing bypass
breakers is acceptable. The basis for this conclusion includes recognition
of the fact that a readily available means does not exist to permit testing
of the automatic trip feature of bypass breakers and that confirmation of
the operability of the shunt trip attachment when the breaker is placed in
service provides additional assurance that the bypass breaker could be
tripped via a manual reactor trip. Therefore, if a bypass breaker is not
tripped via its undervoltage trip attachment due to a valid automatic trip
signal during breaker testing, or a manual reactor trip is intentionally
initiated, greater assurance will be provided for the capability.to trip a
bypass breaker.
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As a consequence of the staff review of Westinghouse plants with relay logic
it was recognized that for some plants the manual reactor trip function does
not actuate the shunt trip attachment of bypass breakers, but rather the
undervoltage trip attachment. Further, the capability is provided from the
protection system racks to individually trip each bypass breaker manually.
Therefore, for plants with this design the bases for testing the operability
of bypass breakers, when they are placed in service for testing of reactor
trip breakers, would be met by a trip of the undervoltage trip attachment of
the bypass breakers initiated manually from the protection system racks.
Also with regards to the test of the manual reactor trip function for plants
with this design, this test should confirm the operability of the
undervoltage trip.
Accordingly, Table 4.3-1 of the STS will be revised to include surveillance
test requirements for reactor trip bypass breakers as follows:
1. Shunt trip attachment operability tests prior to placing the breaker in
service.
2. Undervoltage trip attachment operability tests at least once per 18
months.
3. Manual reactor trip operability tests at least once per 18 months.
If the shunt trip attachment is actuated on a manual reactor trip, the
test shall independently verify the operability of the undervoltage and
shunt trip circuits.
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For plants that do not actuate the shunt trip attachment of the bypass
breakers on a manual reactor trip, item 1 would be replaced by a remote
manual undervoltage trip attachment operability test when the bypass breaker
is placed in service for reactor trip breaker testing.
Enclosed are marked-up pages of the applicable STS tables with these
changes. Until such time that these changes are incorporated in the STS,
proposed changes to plant specific technical specifications will be
evaluated by the staff based on this guidance.
For plants which do not have bypass breakers, technical specification
changes are not required at this time. The need for any change to technical
specifications will be identified on a plant specific basis following the
staff review of licensee responses to Item 4.5 of Generic Letter 83-28.
Page Last Reviewed/Updated Tuesday, March 09, 2021
Page Last Reviewed/Updated Tuesday, March 09, 2021