TSTF-500
text
1.0 Description
This Traveler updates and replaces TSTF-360-A, Revision 1, "DC Electrical Rewrite."
The update reflects the current NRC position on the proposed changes and approval of
recent plant-specific amendments to adopt TSTF-360. This update also provides
sufficient information for the NRC to write a model Safety Evaluation and to offer
adoption of these changes under the Consolidated Line Item Improvement Process
(CLIIP). To facilitate the NRC's publication of TSTF-500 under the CLIIP, a draft model
application is included as Attachment C.
The proposed changes request new actions for an inoperable battery charger and alternate
battery charger testing criteria for Limiting Condition for Operation (LCO) 3.8.4, "DC
Sources - Operating," and LCO 3.8.5, "DC Sources - Shutdown." The proposed changes
also include the relocation of a number of Surveillance Requirements (SRs) in TS 3.8.4
that perform preventive maintenance on the safety related batteries to a licenseecontrolled
program . It is proposed that LCO 3.8.6, "Battery Parameters," be modified by
relocating Table 3.8.6-1, "Battery Cell Parameter Requirements," to a licensee-controlled
program, and that specific actions with associated Completion Times for out-of-limits
conditions for battery cell voltage, electrolyte level, and electrolyte temperature be added
to TS 3.8.6. In addition, specific SRs are being proposed for verification of these
parameters.
A new program is being proposed for Section 5.5 of the Administrative Controls for the
maintenance and monitoring of station batteries. The items proposed to be relocated will
be contained within this new program, titled the "Battery Monitoring and Maintenance
Program."
The proposed Traveler provides new Actions for an inoperable battery charger and
alternate battery charger testing criteria. The longer Completion Time for an inoperable
battery charger will allow additional time for maintenance and testing. In addition, a
number of Surveillance Requirements are relocated to licensee control. Monitoring of
battery cell parameter requirements and performance of battery maintenance activities are
relocated to a licensee-controlled program. The Technical Specification requirements are
revised from requirements on battery cells to requirements on the battery. This focuses
the requirements on the assumed safety function of the battery.
2.0 Proposed Change
The proposed change revises the following Specifications:
Specification 3.8.4, "DC Sources Operating," to add Conditions for inoperable battery
chargers and inoperable batteries. Specification 3.8.4 is also revised to relocate the
Surveillances on battery corrosion, connection resistance, visual inspection, terminal
connection, and discharge tests to an administrative program or to other specifications.
Specification 3.8.5, "DC Sources - Shutdown," to add Conditions for inoperable battery
chargers and inoperable batteries. The list of TS 3.8.4 Surveillances that must be met is
also revised to be consistent with the changes to TS 3.8.4.
Specification 3.8.6, "Battery Cell Parameters," is renamed "Battery Parameters."
Table 3.8.6-1 is deleted and the existing Conditions and Surveillances are replaced.
A new Administrative Controls program, titled "Battery Monitoring and Maintenance
Program," is added to Section 5.5, "Programs and Manuals."
3.0 Background
TSTF-360, "DC Electrical Rewrite," was approved by the NRC in December 2000 and
incorporated in Revision 1 of the ISTS NUREGs. It was adopted by some plants as part
of ITS conversion and under some separate license amendments, however success with
adoption of TSTF-360 has been difficult because the NRC Electrical Branch did not
agree with some of the provisions. At the TSTF's request, NRC provided a letter
describing their concerns with TSTF-360 on April 11, 2006. The TSTF formed a
Working Group including the sites that currently had TSTF-360 based LARs under
review by the NRC and with industry experts. The Working Group developed responses
and was able to address the NRC's concerns.
At the recommendation of the NRC, the TSTF utilized the NRC's December 19, 2006
approval of a LaSalle amendment request to adopt TSTF-360 (Accession number
ML063200215) as the basis for developing this Traveler.
TSTF-360-A was incorporated into Revision 2 of the ISTS NUREGs. Attachment A
shows the changes to the current version of the ISTS NUREGS (Revision 3.1) to
incorporate the differences between TSTF-360-A and TSTF-500. Attachment B shows
the changes to Revision 1 of the ISTS NUREGs to incorporate TSTF-500. For plants that
have not adopted TSTF-360-A, the changes in Attachment B should be used as a model
for the plant-specific TS changes.
4.0 Technical Analysis
The standard Technical Specifications for pressurized water reactors (NUREG-1430, --
1431, and -1432) uses the term "train" to refer to the independent and redundant
subsystems that make up the DC electrical power system. The boiling water reactor
standard Technical Specifications (NUREG-1433 and NUREG-1434) use the term
"division." For the purpose of this Traveler, the term "subsystem" is used but the
discussion is equally applicable to trains or divisions.
4.1 DC Electrical Power System Design
The station DC electrical power system provides the AC emergency power system with
control power. It also provides both motive and control power to selected safety related
equipment and preferred AC vital bus power (via inverters). As required by 10 CFR 50,
Appendix A, GDC 17, the DC electrical power system is designed to have sufficient
independence, redundancy, and testability to perform its safety functions, assuming a
single failure.
The DC electrical power system typically consists of two independent and redundant
safety related Class 1E DC electrical power subsystems. Each subsystem consists of the
batteries, the associated battery charger(s) for each battery, and all the associated control
equipment and interconnecting cabling.
During normal operation, the DC load is powered from the battery chargers with the
batteries floating on the system. In case of loss of normal power to the battery charger,
the DC load is automatically powered from the station batteries.
Each battery is separately housed in a ventilated room apart from its charger and
distribution centers. Each subsystem is located in an area separated physically and
electrically from the other subsystem to ensure that a single failure in one subsystem does
not cause a failure in a redundant subsystem. There is no sharing of dedicated
components between redundant Class 1E subsystems, such as batteries, battery chargers,
or distribution panels.
Each battery has adequate storage capacity to meet the duty cycle(s) assumed in the
accident analyses. The battery is normally designed with additional capacity above that
required by the design duty cycle to allow for temperature variations and other factors.
Each DC electrical power subsystem battery charger has ample power output capacity for
the steady state operation of connected loads required during normal operation, while at
the same time maintaining its battery bank fully charged. Each battery charger also has
sufficient excess capacity to restore the battery from the design minimum charge to its
fully charged state while supplying normal steady state loads.
The battery charger is normally in the float-charge mode. Float-charge is the condition in
which the charger is supplying the connected loads and the battery cells are receiving
adequate current to optimally charge the battery. This assures the internal losses of a
battery are overcome and the battery is maintained in a fully charged state.
When desired, the charger can be placed in the equalize mode. The equalize mode is at a
higher voltage than the float mode and charging current is correspondingly higher. The
battery charger is operated in the equalize mode after a battery discharge or for routine
maintenance. Following a battery discharge, the battery recharge characteristic accepts
current at the current limit of the battery charger (if the discharge was significant, e.g.,
following a battery service test) until the battery terminal voltage approaches the charger
voltage setpoint.
4.2 Differences Between TSTF-360-A and TSTF-500
TSTF-360-A was based on IEEE-450-1995, "IEEE Recommended Practice for
Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for Stationary
Applications." The NRC has not reviewed or endorsed IEEE-450-1995. Therefore, the
changes proposed in TSTF-500 are based on IEEE-450-2002. The NRC has endorsed
IEEE-450-2002 in Regulatory Guide 1.129, Revision 2.
TS 3.8.4, Required Action A.3, and TS 3.8.5, Required Action A.3, contains a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />
Completion Time vice the 7 day Completion Time in TSTF-360-A. Licensees wishing to
adopt a Completion Time for Required Action A.3 longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> will need to
demonstrate that the Completion Time is appropriate for the plant in accordance with the
guidance in Regulatory Guide (RG) 1.177, "An Approach for Plant-Specific, Risk-
Informed Decisionmaking: Technical Specifications," and RG 1.174, "An Approach for
Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific
Changes to the Licensing Basis." Alternatively, the 7 day Completion Time can be
justified by an acceptable method, such as a regulatory commitment that an alternate
means to charge the batteries will be available that is capable of being supplied power
from a power source that is independent of the offsite power supply. Otherwise, the 72
hour Completion Time must be adopted.
TSTF-360-A applied a Reviewer's Note to TS 3.8.6 which stated that licensees must
adopt a Battery Monitoring and Maintenance Program based on IEEE-450-1995. That
Reviewer's Note is deleted in TSTF-500 because it is no longer necessary. Reliance on
IEEE-450 is incorporated in the Battery Monitoring and Maintenance Program.
The Battery Monitoring and Maintenance Program is revised to reference IEEE-450-2002
and Regulatory Guide 1.129, Revision 2 (with exceptions), to require actions to equalize
and test battery cells when the electrolyte level drops below the top of plates instead of
when the electrolyte level drops below the minimum established design limit, to require
actions to verify the remaining cells are > [2.07] V when a cell or cells have been found
to be <[2.13] V. The Program is also revised to state the license controlled program will
contain limits on average electrolyte temperature, battery connection resistance, and
battery terminal voltage; and a requirement to obtain specific gravity readings of all cells
at each discharge test, consistent with manufacturer recommendations.
TSTF-360-A contained two documents: "Battery Primer for Nuclear Power Plants," and
"Assessment of Lead-Acid Battery State of Charge by Monitoring Float Current," which
are also included in this Traveler as Enclosures 1 and 2. These documents provided
justification for using float current instead of specific gravity as a method of monitoring
the state-of-charge for the batteries and establishing a return to service limit. In order use
float current, licensees are required to provide letters from the manufacturers of the
batteries in use at their station supporting the use of float current monitoring instead of
specific gravity monitoring and to provide plant/battery specific bases for the [2] amp
return to service limit. One method of selecting the return to service limit that has been
accepted by the NRC is reserving [5%] of the available design margin above that required
to perform the intended design function. See the "Verifications and Regulatory
Commitments" section, below.
4.3 Proposed Changes to Specification 3.8.4, "DC Sources - Operating"
4.3.1 Proposed Changes to Specification 3.8.4, "DC Sources - Operating" Actions
TS 3.8.4 contains a Condition for one DC electrical train inoperable. The proposed
change adds two additional Conditions, which are exceptions to the existing Condition.
The proposed change to the TS 3.8.4 Actions addresses the condition in which one or two
required battery chargers on one train are inoperable and effectively increases the
Completion Time for an inoperable battery charger from the existing 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to
[72] hours, provided that battery terminal voltage is restored to greater than or equal to
the minimum established float voltage within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, and battery float current is verified
to be is less than or equal to [2] amps once per [12] hours.
The first Condition (new Condition A) applies when one [or two] battery charger[s] on
one train are inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). There
are three Required Actions. The Required Actions provide a tiered response that focuses
on returning the battery to the fully charged state and restoring a fully qualified charger to
Operable status in a reasonable time period. The first Required Action states that the
battery terminal voltage must be restored to greater than or equal to the minimum
established float voltage within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The second Required Action states that the
battery float current must be verified to be ≤ [2] amps once per [12] hours. As stated in a
Reviewer's Note in the Bases, a plant that cannot meet the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Completion Time due
to an inherent battery charging characteristic can propose an alternate time equal to 2
hours plus the time experienced to accomplish the exponential charging current portion of
the battery charge profile following the service test (SR 3.8.4.3). The third Required
Action states that the battery charger[s] must be restored to Operable status. The third
Completion Time is [72] hours.
New Required Action A.1 would provide assurance that a battery discharge is terminated
by requiring that the battery terminal voltage be restored to greater than or equal to the
minimum established float voltage within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The battery charger, in addition to
maintaining battery operability, provides DC control power to AC circuit breakers and
thus supports the recovery of AC power following events such as loss of offsite power or
station blackout (SBO). The 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Completion Time provides an allowance for
returning an inoperable charger to Operable status or for reestablishing an alternate
means of restoring battery terminal voltage to greater than or equal to the minimum
established float voltage. This provides assurance that the battery will be restored to its
fully charged condition from any discharge that might have occurred due to the battery
charger being inoperable. At the end of the 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, a terminal voltage of at least the
minimum established float voltage provides indication that the battery is on the
exponential charging current portion of its recharging cycle.
New Required Action A.2 would require that once per [12] hours, the battery float
current be verified to be less than or equal to [2] amps. This provides an indication that,
if the battery has been discharged as the result of an inoperable battery charger, it has
now been fully charged. If at the expiration of the [12] hour period, the battery float
current is not less than or equal to [2] amps, there may be additional problems and the
battery is considered inoperable. This verification provides assurance that the battery has
sufficient capacity to perform its safety function.
New Required Action A.3 requires restoring inoperable battery charger to Operable
status. Given that the DC bus remains energized, the battery discharge is terminated
based on restoration of the battery terminal voltage (New Required Action A.1), and the
battery is fully recharged based upon battery float current (New Required Action A.2),
there is reasonable basis for extending the restoration time for an inoperable battery
charger beyond the existing [2] hour Completion Time to [72] hours (New Required
Action A.3). The primary justification for the extended Completion Time is the
availability of a spare battery charger that is appropriately sized to perform the design
function of the charger being replaced. As stated in a Reviewer's Note in the Bases, a
licensee wishing to adopt a Completion Time longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> will need to
demonstrate that the Completion Time is appropriate for the plant in accordance with the
guidance in RG 1.177 and RG 1.174. Alternatively, the 7 day Completion Time can be
justified by an acceptable method, such as a regulatory commitment that an alternate
means to charge the batteries will be available that is capable of being supplied power
from a power source that is independent of the offsite power supply. Otherwise, the 72
hour Completion Time must be adopted.
The second Condition (new Condition B) applies when one [or two] batteries on one train
are inoperable. The Required Action states that the battery or batteries must be restored
to Operable status within [2] hours. As stated in a Reviewer's Note in the Bases, a
licensee wishing to request a longer Completion Time will need to demonstrate that the
longer Completion Time is appropriate for the plant in accordance with the guidance in
RG 1.177 and RG 1.174 or provide a regulatory commitment that an alternate means of
charging the batteries is available. With the batteries on one train inoperable, the DC bus
is being supplied by the Operable battery charger(s). Any event that results in a loss of
the AC bus supporting the battery charger(s) will also result in loss of DC power to that
train. Recovery of the AC bus, especially if it is due to a loss of offsite power, will be
hampered by the fact that many of the components necessary for the recovery (e.g., diesel
generator control and field flash, AC load shed and diesel generator output circuit
breakers, etc.) may rely on the batteries. In addition, the energization transients of any
DC loads that are beyond the capability of the battery charger(s) and normally require the
assistance of the batteries will not be able to be restored. The [2] hour limit allows
sufficient time to effect restoration of an inoperable battery given that the majority of the
conditions that lead to battery inoperability (e.g., loss of battery charger, inadequate
battery cell voltage, etc.) are identified in Specifications 3.8.4, 3.8.5, and 3.8.6 and
provide additional Required Actions and associated Completion Times.
Existing Condition A is renumbered Condition C and the exception "for reasons other
than Condition A [or B]" is added. Existing Conditions B and C are renumbered
Conditions D and E with no other changes.
4.3.2 Proposed Changes to Specification 3.8.4, "DC Sources - Operating," Surveillances
SR 3.8.4.1 is proposed to be revised from "Verify battery terminal voltage is ≥ [120] V
on float charge" to "Verify battery terminal voltage is greater than or equal to the
minimum established float voltage." The Frequency of 7 days is unchanged. The value
for the minimum established float voltage is relocated from the Specifications to the TS
Bases.
The purpose of SR 3.8.4.1 is to verify the battery terminal voltage is greater than or equal
to the minimum established float voltage. The specific limiting value for the minimum
operating battery charging float voltage is relocated to the Bases. The battery
manufacturer establishes this voltage to provide the optimum charge on the battery. This
voltage will maintain the battery plates in a condition that supports maintaining the grid
life. This value can be adequately controlled in the TS Bases by the Technical
Specifications Bases Control Program.
SR 3.8.4.2, SR 3.8.4.3, SR 3.8.4.4, and SR 3.8.4.5 are deleted and the associated testing
will be performed under the Battery Monitoring and Maintenance Program.
In accordance with SR 3.0.1, when any SR is not met, the LCO is not met. This is based
on the SRs representing the minimum acceptable requirements for operability of the
required equipment. However, for SR 3.8.4.2, SR 3.8.4.3, SR 3.8.4.4, and SR 3.8.4.5,
failure to meet the SR does not necessarily mean that the equipment is not capable of
performing its safety function. Furthermore, the corrective action is generally a routine or
preventive maintenance-type activity. These activities are inappropriate for SRs and can
be controlled in the maintenance programs for batteries.
With regard to the resistance verifications of SR 3.8.4.2 and SR 3.8.4.5, the values are
nominal values and represent limits at which some action should be taken, not necessarily
when the operability of the battery is in question. The plant safety analyses do not assume
a specific battery inter-cell connection resistance value, but typically assume that the
batteries will supply adequate power. Therefore, the key issue is the overall battery
connection resistance. Between surveillances, the resistance of each battery inter-cell
connection varies independently from all the others. Some of these connection resistance
values may be higher or lower than others, and the battery will still be able to perform its
function and should not be considered inoperable. Overall connection resistance has a
direct impact on operability and is adequately determined as acceptable through
completion of the battery service and or modified performance discharge tests. Therefore,
these activities are more appropriately controlled under the proposed Battery Monitoring
and Maintenance Program. Licensees must provide a basis for the relocated cell
connection resistance limit ([150 μOhm] or a revised monitoring value).
SR 3.8.4.6 (now SR 3.8.4.2) specifies battery charger current requirements for each DC
source, and its purpose is to verify the design capacity of each battery charger. The
proposed change revises this SR to be consistent with SR 3.8.4.1 by replacing the specific
voltage limits with "greater than or equal to the minimum established float voltages."
The voltage requirements are based on the battery charger voltage level after a response
to a loss of AC power. As stated above, the battery manufacturer establishes this voltage
limit to provide the optimum charge on the battery and to maintain the battery plates in a
condition that supports maintaining the battery grid life. This value can be adequately
controlled in the TS Bases by the Technical Specifications Bases Control Program.
An alternative criteria is added to SR 3.8.4.6 (now SR 3.8.4.2), which states, "Verify each
battery charger can recharge the battery to the fully charged state within [24] hours while
supplying the largest combined demands of the various continuous steady state loads,
after a battery discharge to the bounding design basis event discharge state."
This is an alternate method for verifying the design capacity of each battery charger. As
described in the revised Bases for SR 3.8.4.2, this test would occur following a service,
performance or modified performance test. The level of loading required may not
normally be available following the battery service test and may need to be supplemented
with additional loads. The duration of this test may be longer than the charger sizing
criteria since the battery recharge is affected by float voltage, temperature, and the
exponential decay in charging current. If each battery charger is capable of recharging its
respective battery within [24] hours while supplying the largest combined demands of the
various continuous steady state loads, after a battery discharge to the bounding designbasis
event discharge state, the proposed alternate testing criteria would satisfy the
purpose of SR 3.8.4.2.
SR 3.8.4.6 (now SR 3.8.4.2) is revised to eliminate a Note. The Note states, "This
Surveillance shall not be performed in MODE 1, 2, or 3. However, credit may be taken
for unplanned events that satisfy this SR." This restriction is eliminated as the alternate
method can be performed in MODE 1, 2, or 3 without affecting plant safety.
The Note to SR 3.8.4.7 (now SR 3.8.4.3) is revised to eliminate the "once per 60 months"
restriction on performing the modified performance discharge test instead of the service
test, effectively allowing the modified performance test to be used instead of the service
test at any time. The licensee must confirm that the modified performance discharge test
completely encompasses the load profile of the battery service test and that it adequately
confirms the intent of the service test to verify the battery capacity to supply the design
basis load profile.
SR 3.8.4.8 is relocated to TS 3.8.6. The relocation is discussed below.
4.3.4 Proposed Changes to Specification 3.8.4, "DC Sources - Operating," Bases
The Bases of Specification 3.8.4 are revised to reflect the changes described above. No
other substantive changes are made.
4.4 Proposed Changes to Specification 3.8.5, "DC Sources - Shutdown"
4.4.1 Proposed Changes to Specification 3.8.5, "DC Sources - Shutdown" Actions
TS 3.8.5 contains a Condition for one or more DC electrical subsystems inoperable. The
proposed change adds an additional Condition, which is an exception to the existing
Condition. The existing Condition is renamed Condition B and modified to state "One or
more DC electrical power subsystems inoperable for reasons other than Condition A."
An addition condition joined by an OR is added to Condition A (new Condition B) which
states, "Required Actions and associated Completion Time of Condition A not met." The
Required Actions of Condition A (new Condition B), which require declaring affected
required features inoperable or suspending core alterations and movement of irradiated
fuel assemblies in the [secondary] containment, are not changed.
TS 3.8.5 requires DC electrical power sources to be Operable to support specific
equipment and capabilities in MODE 5 and 6 and during movement of irradiated fuel
assemblies. Depending on the plant design, this may require both DC electrical trains to
be Operable. The new Condition A is bracketed and is included only when the plantspecific
implementation of TS 3.8.5 may require both trains of the DC electrical power
system to be Operable. If the plant-specific implementation of LCO 3.8.5 required only
one train of the DC electrical power system to be Operable, then Condition A is omitted
and Condition B is renumbered as Condition A.
The new Condition A applies when one [or two] battery charger[s] on one train are
inoperable and the redundant train battery and charger[s] are Operable. There are three
Required Actions. The first Required Action states that the battery terminal voltage must
be restored to greater than or equal to the minimum established float voltage within 2
hours. The second Required Action states that the battery float current must be verified
to be ≤ [2] amps once per [12] hours. As stated in a Reviewer's Note in the Bases, a plant
that cannot meet the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Completion Time due to an inherent battery charging
characteristic can propose an alternate time equal to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> plus the time experienced to
accomplish the exponential charging current portion of the battery charge profile
following the service test (SR 3.8.4.3). The third Required Action states that the battery
charger[s] must be restored to Operable status. The third Completion Time is [72] hours.
As stated in a Reviewer's Note in the Bases, a licensee wishing to adopt a Completion
Time longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> must demonstrate that the Completion Time is appropriate for
the plant in accordance with the guidance in RG 1.177 and RG 1.174. Alternatively, the
7 day Completion Time can be justified by an acceptable method, such as a regulatory
commitment that an alternate means to charge the batteries will be available that is
capable of being supplied power from a power source that is independent of the offsite
power supply. Otherwise, the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time must be adopted.
As described in the discussion of the changes to TS 3.8.4, above, given that the DC bus
remains energized, the battery discharge is terminated based on restoration of the battery
terminal voltage (New Required Action A.1), and the battery is fully recharged based
upon battery float current (New Required Action A.2), there is reasonable basis for
extending the restoration time for an inoperable battery charger beyond the existing [2]
hour Completion Time to [72] hours (New Required Action A.3).
The change to the existing Condition A (new Condition B) to address the situation in
which the Required Actions and associated Completion Times of new Condition A are
not met provides conservative actions to be followed.
4.4.2 Proposed Changes to Specification 3.8.5, "DC Sources - Shutdown," Surveillances
SR 3.8.5.1 is revised to reflect the relocation or elimination of Surveillances in TS 3.8.4.
This change is administrative and reflects the changes justified above.
4.4.3 Proposed Changes to Specification 3.8.5, "DC Sources - Shutdown," Bases
The Bases of Specification 3.8.5 are revised to reflect the changes described above. No
other substantive changes are made.
4.5 Proposed Changes to Specification 3.8.6, "Battery Parameters"
4.5.1 Proposed Changes to Specification 3.8.6, "Battery Parameters " Title and LCO and Deletion of Table 3.8.6-1
TS 3.8.6, "Battery Cell Parameters," is renamed "Battery Parameters." The LCO is
revised to refer to battery parameters, instead of battery cell parameters, being within
limits. These changes are editorial and reflect the revised requirements, as described
below.
The TS 3.8.6 LCO is revised to refer to the [name] "electrical power subsystem
batteries" instead of the [name] "batteries," where "name" is "Train A and B" or "station
service and DG," depending on plant type. This adds consistency with the LCO 3.8.4 and
LCO 3.8.5 descriptions of the separate and independent electrical power subsystems and
uses the term "subsystem," which appears in the Conditions, in the LCO.
LCO 3.8.6 is revised to remove the reference to Table 3.8.6-1. Table 3.8.6-1, "Battery
Cell Parameter Requirements," is deleted.
TS Table 3.8.6-1 specifies the battery cell parameter requirements, including electrolyte
level, float voltage, and specific gravity. The Category A and B values of TS Table
3.8.6-1 represent appropriate monitoring levels and appropriate preventive maintenance
levels for long-term battery quality and extended battery life. The definition of Limiting
Condition for Operation (LCO) presented in 10 CFR 50.36 states that LCOs are "the
lowest functional capability or performance levels of equipment required for safe
operation of the facility." As such, the Category A and B values for cell voltage and
electrolyte level do not reflect the 10 CFR 50.36 criteria for LCOs. It is proposed that
these values and the Required Actions associated with restoration be relocated to a
licensee-controlled program, required and described in TS Section 5.5, "Program," and
titled the "Battery Monitoring and Maintenance Program." This provides adequate
assurance that the battery parameter values will continue to be controlled and actions will
be implemented if the battery parameter values are not met. Furthermore, the battery and
its preventive maintenance and monitoring program are under the regulatory
requirements of 10 CFR 50.65, "Requirements for monitoring the effectiveness of
maintenance at nuclear power plants."
The Category C specific limiting values of TS Table 3.8.6-1 for the battery electrolyte
levels have also been proposed to be relocated to a licensee-controlled program.
However, new TS 3.8.6, Conditions C and D, will require the electrolyte temperature
(pilot cell only) and level (any battery cell) to be greater than or equal to minimum
established design limits. Depending on the available excess capacity of the associated
battery, the minimum temperature necessary to support operability of the battery can
vary. Relocating these values to a licensee-controlled program will provide the licensee
with added flexibility to monitor and control this limit at values directly related to the
battery's ability to perform its assumed function.
The TS Table 3.8.6-1, Category C, limiting value for float voltage is eliminated and
instead the new SR 3.8.6.2 will require monitoring of float voltage. This change is
discussed below under SR 3.8.6.2.
The TS Table 3.8.6-1, Category C, limiting value for specific gravity is eliminated as the
method of verifying battery state of charge and instead the new SR 3.8.6.1 will require
monitoring of float current. This change is discussed below under SR 3.8.6.1.
4.5.2 Proposed Changes to Specification 3.8.6, "Battery Parameters " Actions
The existing TS 3.8.6 Condition A is deleted and replaced with the following Conditions:
- New Condition A addresses the condition in which one or more batteries with one or
more battery cells float voltage less than [2.07] V.
- New Condition B addresses the condition in which one or more batteries with float
current greater than [2] amps.
- New Condition C addresses the condition in which one or more batteries with one or
more cells electrolyte level less than the minimum established design limits.
- New Condition D addresses the condition in which one or more batteries with pilot
cell electrolyte temperature less than minimum established design limits.
- New Condition E addresses the condition in which two or more redundant division
battery parameters not within established limits.
Current Condition B will be renamed as new Condition F. The current Condition B
consists of three separate entry Conditions and the Required Action is to declare the
associated battery inoperable. As part of this proposed change, the last two entry
Conditions will be deleted. The deleted Conditions will be replaced with two new
Conditions requiring entry when one or more batteries with one or more battery cells
float voltage of less than [2.07] V or float current greater than [2] amps.
New TS 3.8.6, Condition A addresses what was formerly the Category C limit for float
voltage in TS Table 3.8.6-1. This new Condition would be applicable when one or more
batteries on one train are found with one or more battery cells with a float voltage less
than [2.07] V. Once Condition A has been entered, the battery cell is considered
degraded and the Required Actions are to verify within 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />s: (A.1) the battery
terminal voltage to be greater than or equal to the minimum established float voltage (SR 3.8.4.1), and (A.2) that each battery's float current is less than or equal to [2] amps (SR 3.8.6.1). The above actions assure that there is still sufficient battery capacity to perform
its intended function without considering the battery inoperable. Continued operations up
to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is proposed to allow the restoration of the affected cell(s) voltage to greater
than or equal to [2.07] volts.
New TS 3.8.6, Condition B addresses battery state-of-charge. This new Condition B
would be applicable when one or more batteries is found with a float current greater than
[2] amps. A float current of greater than [2] amps provides an indication that a partial
discharge has occurred. The Required Action is to verify within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> that the battery
terminal voltage is greater than or equal to the minimum established float voltage (SR 3.8.4.1), thus confirming battery charger operability. If the terminal voltage is
satisfactory, Required Action B.2 of Condition B assures that within [12] hours the
battery will be restored to its fully-charged condition from any discharge that might have
occurred due to a temporary loss of the battery charger. As stated in the Reviewer's Note
for Condition B, if a plant cannot meet the [12] hour Completion Time due to an inherent
battery charging characteristic, they can propose an alternate time equal to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> plus
the time experienced to accomplish the exponential charging current portion of the
battery charge profile following the service test (SR 3.8.4.3).
If the terminal voltage is found to be less than the minimum established float voltage, it
indicates that the battery charger is either inoperable or is operating in the current limit
mode. If the battery charger is operating in the current limit mode for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, it is an
indication that the battery has been substantially discharged and likely can not perform its
required design functions. In this case, new Condition F is entered.
If float voltage is not satisfactory, revised Condition F of TS 3.8.6 would be applicable
and the battery must be declared inoperable immediately.
New TS 3.8.6, Condition C addresses the level of the electrolyte in a cell. This new
Condition C would be applicable when one or more batteries is found with one or more
cells' electrolyte level is less than the minimum established design limits. If the level is
above the top of the battery plates, but below the minimum limit (i.e., minimum level
indication mark on the battery cell jar), the battery still has sufficient capacity to perform
its intended safety function and is not considered inoperable. With the cell(s) electrolyte
level below the top of the plates, there is a potential for dry-out and plate degradation.
New Required Actions C.1 and C.2 restore the electrolyte level and ensure that the cause
of the loss of electrolyte level is not due to a leak in the battery cell jar. These changes,
with the additional requirements in the Battery Monitoring and Maintenance Program, are
adequate to ensure that minimum electrolyte levels are maintained.
New TS 3.8.6, Condition D applies to a battery found with a pilot cell electrolyte
temperature less than the minimum established design limit. This Condition would be
applicable when one or more batteries has a pilot cell electrolyte temperature of less than
the minimum established design limits. A low electrolyte temperature limits the current
and power available from the battery. Batteries are normally sized with correction
margins that include temperature and aging, and as previously mentioned, [5] percent
design margin will be maintained. The temperature of the room containing the batteries
is typically monitored during operator rounds. Since batteries have very large thermal
inertia, it is highly probable that a room temperature excursion would be corrected prior
to the battery reaching minimum temperature. The pilot cell temperature is an accurate
representation of the temperature of the battery bank because: (1) batteries having very
large thermal inertia; (2) the batteries are designed with significant margins (i.e.,
temperature, aging, and design); and (3) the monitoring and correction of low battery
room temperatures. Therefore, the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> CT provides a reasonable time to restore the
electrolyte temperature within established limits.
Due to the use of [2.07] V as the minimum limit for cell voltage and the use of pilot cell
temperature in lieu of average cell temperature, changes are necessary in the way pilot
cells are selected. In the past, pilot cells were selected to represent average cells in the
battery. The change to [2.07] V now requires pilot cells to be selected to represent the
lowest voltage cells in the battery. This ensures that the other cells are above the pilot
cell voltage which must remain above the TS limit.
Previously, average battery temperature was monitored instead of pilot cell temperature.
As a result, temperature was not a criterion with selecting a pilot cell. In order to use
pilot cell temperature instead of average battery temperature, temperature must be used as
a criteria when selecting the pilot cell. This may result in different pilot cells for
temperature monitoring and voltage monitoring.
For batteries where it could be shown that the maximum temperature deviation across the
battery did not exceed the IEEE 450 recommended maximum of 5°F, the NRC has
accepted that cell temperature was not a critical parameter. Therefore for these batteries,
cell temperature did not have to be taken into account when selecting pilot cells. For
batteries where the temperature deviation exceeds 5°F, the licensee has several options.
The first is to continue to use average cell temperature and use it in lieu of pilot cell
temperature. The second is to perform the necessary analysis to demonstrate that
sufficient margins exist in sizing to compensate for using the warmest cell as the pilot
cell. Other options include using cell temperature as a criteria in selecting the pilot cell
or to select a separate pilot cell that reflects the average battery temperature.
Another difference in this approach is rotating pilot cells. Past practices have been to
rotate pilot cells on an annual basis and to not reuse cells that have previously been pilot
cells. The reason for rotation and not reusing cells was to prevent loss of specific gravity
by repeated sampling. With the transition to float current monitoring, this concern is no
longer valid and pilot cells should be selected based on the preceding discussion without
regard to whether or not they have been used previously. The same is true for rotating
pilot cells. The Battery Monitoring and Maintenance Program will require pilot cell
selection to be verified following performance of SR 3.8.6.5 ("Verify each battery
connected cell float voltage is ≥ [2.07] V,)" which has a Frequency of 92 days.
New TS 3.8.6, Condition E addresses the condition in which two or more redundant
division battery parameters are not within established limits. If this condition exists,
there is not sufficient assurance that the batteries will be capable of performing their
intended safety function. With redundant batteries involved, loss of function is possible
for multiple systems that depend upon the batteries. The battery parameters for the
affected battery in one division must be restored to within limits within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, which is
consistent with the Completion Time to restore an inoperable DC bus.
New TS 3.8.6, Condition F provides a default condition for battery parameters that fall
outside the allowance of the Required Actions for Condition A, B, C, D, or E. Under this
condition, it is assumed that there is not sufficient capacity to supply the maximum
expected load requirements. New Condition F also addresses the case where one or more
batteries is found with one or more battery cells having a float voltage less than [2.07] V
and a float current greater than [2] amps. This Condition provides reasonable actions to
respond to this Condition.
4.5.3 Proposed Changes to Specification 3.8.6, "Battery Parameters" Surveillances
The existing SR 3.8.6.1 (verify battery cell parameters meet Table 3.8.6-1 Category A
limits), SR 3.8.6.2 (verify battery cell parameters meet Table 3.8.6-1 Category B limits),
and SR 3.8.6.3 (verify average electrolyte temperature of representative cells) are deleted.
The deleted SRs are replaced with SR 3.8.6.1 for float current, SR 3.8.6.2 for pilot cell
voltage, SR 3.8.6.3 for electrolyte level, SR 3.8.6.4 for pilot cell temperature, SR 3.8.6.5
for connected cell voltage, and SR 3.8.6.6 for discharge testing.
The elimination of existing SR 3.8.6.1 and SR 3.8.6.2 is consistent with the elimination
of Table 3.8.6.1, discussed above. The Table 3.8.6-1, Category A and B limits do not
represent a condition in which the batteries cannot perform their function. Therefore,
SRs which verify that the Table 3.8.6-1 Category A and B limits are met are inconsistent
with the 10 CFR 50.36 definition of "Surveillances," and SR 3.0.1, which state that
Surveillances verify that the Limiting Condition of Operation is met. Existing SR 3.8.6.3
is replaced with new SR 3.8.6.4, as discussed below.
New SR 3.8.6.1 requires verification that the float current for each battery is less than or
equal to [2] amps every 7 days. Float current is used to indicate the state-of-charge
instead of specific gravity. The purpose of this SR is to determine the state-of-charge of
the battery. Float charge is the condition in which the battery charger is supplying the
continuous small amount of current (i.e., less than [2] amps) required to overcome the
internal losses of a battery to maintain the battery in a fully charged state. The float
current requirements are based on the float current indicative of a charged battery. As
stated above, the use of float current to determine the state-of-charge of the battery is
consistent with the battery manufacturer recommendations and must be supported by
documentation from the battery manufacturer.
New SR 3.8.6.2 and SR 3.8.6.5 require verification that the float voltage of pilot cells and
all connected cells are greater than or equal to [2.07] V every 31 and 92 days,
respectively. This voltage level represents the point at which battery operability is in
question. The Battery Monitoring and Maintenance Program in TS Section 5.5 will
include actions to restore battery cells with float voltage less than [2.13] V and actions to
verify that the remaining cells are greater than or equal to [2.07] V when a cell or cells
have been found to be less than [2.13] V.
New SR 3.8.6.3 requires verification that the connected cell electrolyte level of each
battery is greater than or equal to the minimum established design limits every 31 days.
Operation of the batteries at electrolyte levels greater than the minimum established
design limit ensures that the battery plates do not suffer physical damage and continue to
maintain adequate electron transfer capability.
New SR 3.8.6.4 requires verification that the temperature of each battery pilot cell is
greater than or equal to the minimum established design limits every 31 days. It replaces
existing SR 3.8.6.3, which required verifying the average (versus pilot cell) electrolyte
temperature every 92 days. As discussed above, batteries have very large thermal inertia;
the batteries are designed with significant margins (i.e., temperature, aging, and design);
and there is monitoring and correction of low battery room temperatures. As a result, the
pilot cell temperature is an accurate representation of the temperature of the battery bank
and is adequate to ensure that the minimum electrolyte temperature is maintained.
However, because only the pilot cell temperature is determined, the Frequency is
increased from 92 days to 31 days.
The specific limiting values for the battery electrolyte temperature and level are relocated
to licensee control. SR 3.8.6.3 and SR 3.8.6.4, respectively, require the electrolyte level
and temperature to be greater than or equal to the "minimum established design limits."
Depending on the available excess capacity of the associated battery, the minimum
temperature necessary to support operability of the battery can vary. Relocation to
licensee controlled programs can allow flexibility to monitor and control this limit at
values directly related to the battery ability to perform its assumed function.
The new SR 3.8.6.6 is relocated from existing SR 3.8.4.8. Relocating existing SR 3.8.4.8
to new SR 3.8.6.6 is appropriate because the SR demonstrates the operability of the
battery, and is therefore more appropriate to be included in TS Section 3.8.6.
4.5.4 Proposed Changes to Specification 3.8.6, "Battery Parameters " Bases
The Bases of Specification 3.8.6 are revised to reflect the changes described above.
The Bases for SR 3.8.6.1 specify that the equipment that is used to monitor float current
will have the necessary accuracy and capability to measure electrical currents in the
expected range.
4.6 Proposed Addition of the "Battery Maintenance and Monitoring Program" to Section 5.5 of the TS
A new administrative program, the Battery Monitoring and Maintenance Program, is
added to Section 5.5, "Programs," of the TS. The monitoring of the current battery
parameters (i.e., specific gravity, electrolyte level, cell temperature, float voltage,
connection resistance, and physical condition) is relocated to this program. This will
ensure that the battery parameter values will continue to be controlled and that actions
will be implemented should the battery parameter value not be met. Furthermore, the
battery and its preventive maintenance and monitoring program are under the regulatory
requirements of 10 CFR 50.65. The licensee's program should include a provision to
obtain specific gravity readings of all cells at each discharge test, per manufacturer and
NRC recommendations.
The program states:
This Program provides controls for battery restoration and maintenance.
The program shall be in accordance with IEEE Standard (Std) 450-2002,
"IEEE Recommended Practice for Maintenance, Testing, and
Replacement of Vented Lead-Acid Batteries for Stationary Applications,"
as endorsed by Regulatory Guide 1.129, Revision 2 (RG), with RG
exceptions and program provisions as identified below:
a. The program allows the following RG 1.129, Revision 2 exceptions:
1. Battery temperature correction may be performed before or
after conducting discharge tests.
2. RG 1.129, Regulatory Position 1, Subsection 2, "References,"
is not applicable to this program.
3. In lieu of RG 1.129, Regulatory Position 2, Subsection 5.2,
"Inspections," the following shall be used: "Where reference is
made to the pilot cell, pilot cell selection shall be based on the
lowest voltage cell in the battery.”
4 In Regulatory Guide 1.129, Regulatory Position 3, Subsection
5.4.1, "State of Charge Indicator," the following statements in
paragraph (d) may be omitted: "When it has been recorded that
the charging current has stabilized at the charging voltage for
three consecutive hourly measurements, the battery is near full
charge. These measurements shall be made after the initially
high charging current decreases sharply and the battery voltage
rises to approach the charger output voltage."
5. In lieu of RG 1.129, Regulatory Position 7, Subsection 7.6,
"Restoration", the following may be used: "Following the test,
record the float voltage of each cell of the string."
b. The program shall include the following provisions:
1. Actions to restore battery cells with float voltage < [2.13] V;
2. Actions to determine whether the float voltage of the
remaining battery cells is ≥ [2.13] V when the float voltage of
a battery cell has been found to be < [2.13] V;
3. Actions to equalize and test battery cells that had been
discovered with electrolyte level below the top of the plates;
4. Limits on average electrolyte temperature, battery connection
resistance, and battery terminal voltage; and
5. A requirement to obtain specific gravity readings of all cells at
each discharge test, consistent with manufacturer
recommendations.
The exceptions to Regulatory Guide 1.129, Revision 2, are needed to make the
Regulatory Guide requirements consistent with the proposed Technical Specification
requirements, allow reasonable technical approaches, and be applicable to operating
plants, as described below:
Exception 1: Regulatory Guide 1.129 states that temperature correction must be
performed before and after the test. IEEE-450-2002 recommends
performing temperature correction before or after the test and this is
adequate to obtain accurate test results.
Exception 2: This change excludes the Regulatory Guide 1.129 referenced documents,
as they are not relevant to the program.
Exception 3: Regulatory Guide 1.129, Regulatory Position 2, states, "Where reference
is made to the pilot cell, pilot cell selection shall be based on finding an
average cell that is representative of the entire battery’s individual cell
voltage and specific gravity readings." This position is inconsistent with
the treatment of pilot cells in TSTF-500. As stated in the justification
(above), "In the past, pilot cells were selected to represent average cells in
the battery. The change to [2.07] V now requires pilot cells to be selected
to represent the lowest voltage cells in the battery. This ensures that the
other cells are above the pilot cell voltage which must remain above the
TS limit."
Exception 4: The following statements are excluded from Regulatory Position 3,
subsection 5.4.1, "When it has been recorded that the charging current has
stabilized at the charging voltage for three consecutive hourly
measurements, the battery is near full charge. These measurements shall
be made after the initially high charging current decreases sharply and the
battery voltage rises to approach the charger output voltage." This is
inconsistent with the Operability requirements used in the proposed TS,
which state that verifying battery float current to be ≤ [2] amps while on
float charge determines the battery is fully charged (See SR 3.8.6.1).
Exception 5: Regulatory Guide 1.129, Regulatory Position 7, recommends recording
the specific gravity and float voltage of each cell in the string following
the test. The Battery Monitoring and Maintenance Program requires
obtaining specific gravity readings of all cells at each discharge test,
consistent with manufacturer recommendations. The provision to follow
the manufacturer's recommendations is a reasonable allowance given that
the battery manufacturer is qualified to determine the benefit of the
readings.
4.7 Verifications and Regulatory Commitments
In order to adopt this change, licensees must make the following verifications and
regulatory commitments in their license amendment request (LAR). It is anticipated that
these verifications and commitments are captured in the CLIIP model application.
4.7.1 Verifications
1. In an attachment to the LAR, the licensee must provide letters from the manufactures
of the batteries used at the plant verifying the acceptability of using float current
monitoring instead of specific gravity monitoring as a reliable and accurate indication
of the state-of-charge of the battery and that this will hold true over the life of the
battery.
2. The licensee must verify that battery room temperature is routinely monitored such
that a room temperature excursion could reasonably expect to be detected and
corrected prior to the average battery electrolyte temperature dropping below the
minimum electrolyte temperature.
3. The licensee must verify that the equipment that will be used to monitor float current
under SR 3.8.6.1 will have the necessary accuracy and capability to measure
electrical currents in the expected range.
4. If the licensee requests a Completion Time greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for TS 3.8.4,
Required Action A.3, and / or TS 3.8.5, Required Action A.3, the licensee must verify
the availability of a spare battery charger that is appropriately sized. As stated in a
Reviewer's Note in the Bases, a licensee wishing to adopt a longer Completion Time
must also demonstrate that the Completion Time is appropriate for the plant in
accordance with the guidance in Regulatory Guide 1.177, "An Approach for Plant-
Specific, Risk-Informed Decisionmaking: Technical Specifications," and Regulatory
Guide 1.174, "An Approach for Using Probabilistic Risk Assessment in Risk-
Informed Decisions on Plant-Specific Changes to the Licensing Basis."
Alternatively, the 7 day Completion Time can be justified by an acceptable alternate
method, such as a regulatory commitment that an means to charge the batteries will
be available that is capable of being supplied power from a power source that is
independent of the offsite power supply.
5. If the licensee requests a Completion Time greater than 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> for TS 3.8.4,
Required Action B.1 or C.1, the licensee must demonstrate that the Completion Time
is appropriate for the plant in accordance with the guidance in Regulatory Guide 1.177, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Technical
Specifications," and Regulatory Guide 1.174, "An Approach for Using Probabilistic
Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the
Licensing Basis."
6. The cell resistance limits in existing SR 3.8.4.5 are relocated to the Battery
Monitoring and Maintenance Program. Licensees must provide a brief description of
the basis for the cell connection resistance limit based on the vendor specification of
inter-cell resistance, voltage drop at the connection, or overall battery resistance.
7. In order to delete the SR 3.8.4.7 (now SR 3.8.4.3) Note "once per 60 months"
restriction on performing the modified performance discharge test instead of the
service test, the licensee must confirm that the modified performance discharge test
completely encompasses the load profile of the battery service test and that it
adequately confirms the intent of the service test to verify the battery capacity to
supply the design basis load profile.
4.7.2 Commitments
1. The [2] amp float current value is an indication that the battery is [95] percent
charged. The licensee must provide a regulatory commitment to maintain a
[5] percent design margin for the batteries.
2. The licensee-controlled program, required and described in TS Section 5.5,
"Programs and Manuals," and titled the "Battery Monitoring and Maintenance
Program," will require verification of the selection of the pilot cell or cells when
performing SR 3.8.6.5.
5.0 Regulatory Analysis
5.1 No Significant Hazards Consideration
The TSTF has evaluated whether or not a significant hazards consideration is involved
with the proposed generic change by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:
1. Does the proposed change involve a significant increase in the probability or
consequences of an accident previously evaluated?
Response: No.
The proposed changes restructure the Technical Specifications (TS) for the direct
current (DC) electrical power system . The proposed changes add actions to
specifically address battery charger inoperability. The DC electrical power system,
including associated battery chargers, is not an initiator of any accident sequence
analyzed in the Updated Final Safety Analysis Report (UFSAR). Operation in
accordance with the proposed TS ensures that the DC electrical power system is
capable of performing its function as described in the UFSAR. Therefore, the
mitigative functions supported by the DC electrical power system will continue to
provide the protection assumed by the analysis.
The relocation of preventive maintenance surveillances, and certain operating limits
and actions, to a newly-created licensee-controlled Battery Monitoring and
Maintenance Program will not challenge the ability of the DC electrical power system
to perform its design function. Appropriate monitoring and maintenance, consistent
with industry standards, will continue to be performed . In addition, the DC electrical
power system is within the scope of 10 CFR 50.65, "Requirements for monitoring the
effectiveness of maintenance at nuclear power plants," which will ensure the control
of maintenance activities associated with the DC electrical power system .
The integrity of fission product barriers, plant configuration, and operating
procedures as described in the UFSAR will not be affected by the proposed changes.
Therefore, the consequences of previously analyzed accidents will not increase by
implementing these changes.
Therefore, the proposed change does not involve a significant increase in the
probability or consequences of an accident previously evaluated.
2. Does the proposed change create the possibility of a new or different kind of accident
from any accident previously evaluated?
Response: No.
The proposed changes involve restructuring the TS for the DC electrical power
system. The DC electrical power system, including associated battery chargers, is not
an initiator to any accident sequence analyzed in the UFSAR. Rather, the DC
electrical power system is used to supply equipment used to mitigate an accident.
Therefore, the proposed change does not create the possibility of a new or different
kind of accident from any accident previously evaluated.
3. Does the proposed change involve a significant reduction in a margin of safety?
Response: No.
The margin of safety is established through equipment design, operating parameters,
and the setpoints at which automatic actions are initiated. The proposed changes will
not adversely affect operation of plant equipment. These changes will not result in a
change to the setpoints at which protective actions are initiated. Sufficient DC
capacity to support operation of mitigation equipment is ensured. The changes
associated with the new battery maintenance and monitoring program will ensure that
the station batteries are maintained in a highly reliable manner. The equipment fed by
the DC electrical sources will continue to provide adequate power to safety related
loads in accordance with analysis assumptions.
Based on the above, the TSTF concludes that the proposed change presents no significant
hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly,
a finding of "no significant hazards consideration" is justified.
5.2 Applicable Regulatory Requirements / Criteria
The following NRC requirements and guidance document are applicable to the review of
the proposed change.
Title 10 of the Code of Federal Regulations (10 CFR) Part 50 Appendix A, General
Design Criterion (GDC) 17, "Electric power systems," requires, in part, that nuclear
power plants have onsite and offsite electric power systems to permit the functioning of
structures, systems, and components (SSCs) that are important to safety. The onsite
system is required to have sufficient independence, redundancy, and testability to
perform its safety function, assuming a single failure. The offsite power system is
required to be supplied by two physically independent circuits that are designed and
located so as to minimize, to the extent practical, the likelihood of their simultaneous
failure under operating and postulated accident and environmental conditions. In
addition, this criterion requires provisions to minimize the probability of losing electric
power from the remaining electric power supplies as a result of loss of power from the
unit, the offsite transmission network, or the onsite power supplies.
GDC 18, "Inspection and testing of electric power systems," requires that electric power
systems that are important to safety must be designed to permit appropriate periodic
inspection and testing.
10 CFR 50.63, "Loss of all alternating current power," requires that each light-water
cooled nuclear power plant licensed to operate must be able to withstand for a specified
duration and recover from a station blackout (SBO).
10 CFR 50.36, "Technical specifications," requires a licensee’s TSs to establish limiting
conditions for operation (LCOs), which include completion times (CTs) for equipment
that is required for safe operation of the facility.
10 CFR 50.65, "Requirements for monitoring the effectiveness of maintenance at nuclear
power plants," requires that preventive maintenance activities must not reduce the overall
availability of the SSCs.
In conclusion, based on the considerations discussed above, (1) there is reasonable
assurance that the health and safety of the public will not be endangered by operation in
the proposed manner, (2) such activities will be conducted in compliance with the
Commission’s regulations, and (3) the approval of the proposed change will not be
inimical to the common defense and security or to the health and safety of the public.
6.0 Environmental Considerations
A review has determined that the proposed change would change a requirement with
respect to installation or use of a facility component located within the restricted area, as
defined in 10 CFR 20, or would change an inspection or surveillance requirement.
However, the proposed change does not involve (i) a significant hazards consideration,
(ii) a significant change in the types or significant increase in the amounts of any
effluents that may be released offsite, or (iii) a significant increase in individual or
cumulative occupational radiation exposure. Accordingly, the proposed change meets the
eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore,
pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental
assessment need be prepared in connection with the proposed change.
7.0 References
1. Letter from Exelon to U.S. NRC dated December 9, 2004, "Request for Amendment
to Technical Specifications Associated With Direct Current Electrical Power,"
(ML043450492).
2. Letter from U.S. NRC to Exelon dated December 19, 2006, "LaSalle County Station,
Units 1 And 2 - Issuance Of Amendments Re: Technical Specification Task Force
Standard Technical Specification Change Traveler 360, Revision 1, "DC Electric
Rewrite" (TAC Nos. Md5771 And Md5772)."
3. Technical Specifications Task Force Traveler TSTF-360-A, Revision 1, "DC
Electrical Rewrite," dated November 11, 2000.
4. Letter from William Beckner (NRC) to Anthony Pietrangelo (NEI) dated December
18, 2000, approving TSTF-360, Revision 1.