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| number = ML072830161 | | number = ML072830161 | ||
| issue date = 09/05/2007 | | issue date = 09/05/2007 | ||
| title = | | title = Technical Specification Bases, B 3.6 Containment Systems, Pages B 3.6.1-1 Through B 3.6.8-4 | ||
| author name = | | author name = | ||
| author affiliation = Constellation Energy Group | | author affiliation = Constellation Energy Group |
Revision as of 08:08, 10 February 2019
ML072830161 | |
Person / Time | |
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Site: | Calvert Cliffs |
Issue date: | 09/05/2007 |
From: | Constellation Energy Group |
To: | Office of Nuclear Reactor Regulation |
References | |
Download: ML072830161 (44) | |
Text
Containment B 3.6.1 B 3.6 CONTAINMENT SYSTEMS B 3.6.1 Containment
BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.1-1Revision 2BACKGROUNDThe C ontainment Structureconsists of the concretebuilding
, its steel liner, and the penetrations through this structure. The structure is designed to contain radioactive material that may be released from the reactor core following a Design Basis Accident (DBA). Additionally, this
structure provides shielding from the fission products that
may be present in the containment atmosphere following
accident conditions.
The C ontainment Structure is a reinforced concrete structure with a cylindrical wall, a flat foundation mat, and a shallow dome roof. The C ontainment Structure has ungrouted tendons, therefore, the cylinder wall is prestressed with a
post-tensioning system in the vertical and horizontal directions, and the dome roof is prestressed utilizing a
three-way post-tensioning system. The inside surface of the C ontainment Structure is lined with a carbon steel liner to ensure a high degree of leak tightness during operating and
accident conditions.
The concrete building is required for structural integrity of the C ontainment Structure under DBA conditions. The steel liner and its penetrations establish the leakage limiting boundary of the C ontainment Structure. Maintaining the C ontainment Structure OPERABLE limits the leakage of fission product radioactivity from the C ontainment Structure to the environment.
Surveillance Requirement (SR) 3.6.1.1leakage rate requirements comply withReference 1
, as modified by approved exemptions.
The isolation devices for the penetrations in the containment boundary are a part of the containment leak tight barrier. To maintain this leak tight barrier:a.All penetrations required to be closed during accident conditions are either:
1.capable of being closed by an OPERABLE automatic containment isolation system, or Containment B 3.6.1 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.1-2Revision 22.closed by manual valves, blind flanges, or de-activated automatic valves secured in their closed positions, except as provided in Limiting Condition for Operation (LCO) 3.6.3;b.Each air lock is OPERABLE, except as provided in LCO 3.6.2;c.The equipment hatch is closed and sealed.APPLICABLEThe safety design basis for the C ontainment Structure isSAFETY ANALYSESthat the C ontainment Structure must withstand the pressures and temperatures of the limiting DBA without exceeding the
design leakage rate.
The DBAs that result in a release of radioactive material within C ontainment Structure are a loss of coolant accident (LOCA), a main steam line break (SLB), and a control element assembly (CEA) ejection accident (Reference 2 , Chapter 14
).In the analysis of each of these accidents, it is assumed
that C ontainment Structure is OPERABLE
, such that release of fission products to the environment is controlled by the
rate of C ontainment Structure leakage. The C ontainment Structure was designed with an allowable leakage rate of 0.20% of containment air weight per day (Reference 2, Chapter 5). This leakage rate is defined inReference 1
, as L a: the maximum allowable containment leakage rate at the calculated maximum peak containment pressure (P a) of 49.4 psig, which results from the limiting design basis LOCA (Reference 2 , Chapter 14
).Satisfactory leakage rate test results are a requirement for
the establishment of C ontainment Structure OPERABILITY.
The C ontainment Structure satisfies 10 CFR 50.36(c)(2)(ii), Criterion 3.LCOContainment OPERABILITY is maintained by limiting leakage to 1.0 L a (346,000 SCCM), except prior to the first startup after performing a required Containment Leakage Rate Testing
Program leakage test. At this time the applicable leakage
limits must be met.
Containment B 3.6.1 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.1-3Revision 2 Compliance with this LCO will ensure a containment configuration, including an equipment hatch, that is
structurally sound and that will limit leakage to those
leakage rates assumed in the safety analysis.
Individual leakage rates specified for the containment air lock (LCO 3.6.2) are not specifically part of the acceptance
criteria of Reference 1. Therefore, leakage rates exceeding these individual limits only result in the C ontainment Structure being inoperable when the leakage results in exceeding the overall acceptance criteria of 1.0 L a.APPLICABILITYIn MODE s 1, 2, 3, and 4, a DBA could cause a release of radioactive material into the C ontainment Structure. In MODE s 5 and 6, the probability and consequences of these events are reduced due to the pressure and temperature
limitations of these MODE
- s. Therefore, the C ontainment Structure is not required to be OPERABLE in MODE 5 to prevent leakage of radioactive material from the C ontainment Structure. The requirements for the C ontainment Structure during MODE 6 are addressed in LCO 3.9.3
.ACTIONSA.1 In the event the C ontainment Structure is inoperable, the C ontainment Structure must be restored to OPERABLE status within one hour. The one hour Completion Time provides a period of time to correct the problem commensurate with the
importance of maintaining the C ontainment Structure during MODE s 1, 2, 3, and 4. This time period also ensures that the probability of an accident (requiring C ontainment OPERABILITY) occurring during periods when the C ontainment Structure is inoperable is minimal.
B.1 and B.2 If the C ontainment Structure cannot be restored to OPERABLE status within the required Completion Time, the plant must
be brought to a MODE in which the LCO does not apply. To
achieve this status, the plant must be brought to at least
MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The
allowed Completion Times are reasonable, based on operating
experience, to reach the required plant conditions from full Containment B 3.6.1 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.1-4Revision 12 power conditions in an orderly manner and without challenging plant systems.SURVEILLANCESR 3.6.1.1 REQUIREMENTS Maintaining the Containment Structure OPERABLE requires
compliance with the visual examinations and leakage rate
test requirements of the Containment Leakage Rate Testing
Program. Failure to meet leakage limits specified in
LCO 3.6.2 and LCO 3.6.3 does not invalidate the
acceptability of these overall leakage determinations unless
their contribution to overall Type A, B, and C leakage
causes that to exceed limits. As left leakage, prior to the
first startup after performing a required Containment Leakage Rate Testing Program, is required to be 0.6 L a (207,600 SCCM) for combined Type B and C leakage and 0.75 L a (259,500 SCCM) for overall Type A leakage. At all other times between required leakage rate tests, the acceptance criteria is based on an overall Type A leakage limit of 1.0 L a. At 1.0 L a , the offsite dose consequences are bounded by the assumptions of the safety analysis. Surveillance Requirement Frequencies are as
required by Containment Leakage Rate Testing Program. These
periodic testing requirements verify that the containment
leakage rate does not exceed the leakage rate assumed in the
safety analysis.
SR 3.6.1.2 For ungrouted, post-tensioned tendons, this SR ensures that
the structural integrity of the Containment Structure will
be maintained in accordance with the provisions of the
Concrete Containment Tendon Surveillance Program. Testing
and Frequency are consistent with the recommendations of Reference 3.
Containment B 3.6.1 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.1-5Revision 24REFERENCES1.10 CFR Part 50, Appendix J, "Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors" Option B, "Performance-Based Requirements"2.Updated Final Safety Analysis Report (UFSAR) 3.American Society of Mechanical Engineers Boiler and Pressure Vessel Code, 1992 Edition through the 1992 Addenda,Section XI, Subsection IWL, Requirements for Class CC Concrete Components of Light-Water Cooled Power Plants as modified and amended by 10 CFR 50.55a Containment Air Locks B 3.6.2 B 3.6 CONTAINMENT SYSTEMS B 3.6.2 Containment Air Locks
BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.2-1Revision 2BACKGROUNDContainment air locks form part of the containment pressure boundary and provide a means for personnel access during all MODE s of operation.
Each air lock is nominally a right circular cylinder, 9 feet-9 inches in diameter for the personnel air lock and
5 feet-9 inches in diameter for the emergency air lock, with
a door at each end. The doors are interlocked to prevent
simultaneous opening. During periods when the C ontainment Structure is not required to be OPERABLE, the door interlock mechanism may be disabled, allowing both doors of an air
lock to remain open for extended periods when frequent
C ontainment Structure entry is necessary. Each air lock door has been designed and tested to certify its ability to
withstand a pressure in excess of the maximum expected pressure following aDBAin the C ontainment Structure. As such, closure of a single door supports the C ontainment Structure OPERABILITY. Each of the doors contains double gasketed seals and local leakage rate testing capability to
ensure pressure integrity. To effect a leak tight seal, the
air lock design uses pressure seated doors (i.e., an
increase in containment internal pressure results in
increased sealing force on each door).
Each personnel air lock is provided with an alarm in the C ontrol R oom that actuates when either door or equalizing valve for a personnel air lock is opened. The alarm senses
door position from a limit switch located on each door and
equalizing valve.
The containment air locks form part of the containment pressure boundary. As such, air lock integrity and leak
tightness is essential for maintaining the containment
leakage rate within limit in the event of a DBA. Not
maintaining air lock integrity or leak tightness may result
in a leakage rate in excess of that assumed in the unit
safety analysis.
Containment Air Locks B 3.6.2 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.2-2Revision 2APPLICABLEThe DBAs that result in a release of radioactive materialSAFETY ANALYSESwithin the C ontainment Structureare aLOCA , a main SLB, and a CEA ejection accident (Reference 1, Chapter 14
). In the analysis of each of these accidents, it is assumed that the C ontainment Structure is OPERABLE such that release of fission products to the environment is controlled by the
rate of containment leakage. The C ontainment Structure was designed with an allowable leakage rate of 0.20% of
containment air weight per day (Reference 1, Chapter 5
).This leakage rate is defined in 10 CFR Part 50, Appendix J, Option B, as the maximum allowable containment leakage rate
at the calculated peak containment internal pressure, P a (49.4 psig), following a design basis LOCA. This allowable
leakage rate forms the basis for the acceptance criteria
imposed on the SRs associated with the air lock.
The containment air locks satisfy 10 CFR 50.36(c)(2)(ii), Criterion 3.LCOEach containment air lock forms part of the containment pressure boundary. As part of the containment pressure
boundary, the air lock safety function is related to control
of the containment leakage rate resulting from a DBA. Thus, each air lock's structural integrity and leak tightness
, are essential to the successful mitigation of such an event.
Each air lock is required to be OPERABLE. For the air lock to be considered OPERABLE, the air lock interlock mechanism
must be OPERABLE, the air lock must be in compliance with
the Type B air lock leakage test, and both air lock doors
must be OPERABLE. The interlock allows only one air lock
door of an air lock to be opened at one time. This
provision ensures that a gross breach of the C ontainment Structure does not exist when the C ontainment Structure is required to be OPERABLE. Closure of a single door in each
air lock is sufficient to provide a leak tight barrier
following postulated events. Nevertheless, both doors are
kept closed when the air lock is not being used for normal
entry into or exit from the C ontainment Structure
.APPLICABILITYIn MODE s 1, 2, 3, and 4, a DBA could cause a release of radioactive material to the containment atmosphere. In MODE s 5 and 6, the probability and consequences of these Containment Air Locks B 3.6.2 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.2-3Revision 2 events are reduced due to the pressure and temperature limitations of these MODE
- s. Therefore, the containment air locks are not required in MODE 5 to prevent leakage of
radioactive material from the C ontainment Structure. The requirements for the containment air locks during MODE 6 are
addressed in LCO 3.9.3
.ACTIONSThe ACTIONS are modified by a Note that allows entry and exit to perform repairs on the affected air lock component.
If the outer door is inoperable, then it may be easily
accessed for most repairs. It is preferred that the air
lock be accessed from inside primary containment by entering
through the other OPERABLE air lock. However, if this is
not practicable, or if repairs on either door must be
performed from the barrel side of the door then it is
permissible to enter the air lock through the OPERABLE door, which means there is a short time during which the
containment boundary is not intact (during access through
the OPERABLE door). The ability to open the OPERABLE door, even if it means the containment boundary is temporarily not
intact, is acceptable because of the low probability of an
event that could pressurize the C ontainment Structure during the short time in which the OPERABLE door is expected to be
open. After each entry and exit, the OPERABLE door must be
immediately closed. If as low as reasonably achievable (ALARA)conditions permit, entry and exit should be via an OPERABLE air lock.
A second Note has been added to provide clarification that, for this LCO, separate Condition entry is allowed for each
air lock. This is acceptable, since the Required Actions
for each Condition provide appropriate compensatory actions
for each inoperable air lock. Complying with the Required
Actions may allow for continued operation, and a subsequent
inoperable air lock is governed by subsequent Condition
entry and application of associated Required Actions. A
third Note has been included that requires entry into the
applicable Conditions and Required Actions of LCO 3.6.1
, when leakage results in exceeding the overall containment
leakage limit.
Containment Air Locks B 3.6.2 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.2-4Revision 2 A.1, A.2, and A.3 With one air lock door inoperable in one or more containment air locks, the OPERABLE door must be verified closed (Required Action A.1) in each affected containment air lock.
This ensures that a leak tight containment barrier is
maintained by the use of an OPERABLE air lock door. This
action must be completed within one hour. This specified time period is consistent with the ACTIONS of LCO 3.6.1, which requires the C ontainment Structure be restored to OPERABLE status within one hour.In addition, the affected air lock penetration must be
isolated by locking closed an OPERABLE air lock door within
the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Completion Time. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Completion Time is
considered reasonable for locking the OPERABLE air lock
door, considering the OPERABLE door of the affected air lock
is being maintained closed.
Required Action A.3 verifies that an air lock with an inoperable door has been isolated by the use of a locked and
closed OPERABLE air lock door. This ensures that an
acceptable containment leakage boundary is maintained. The
Completion Time of once per 31 days is based on engineering
judgment and is considered adequate in view of the low
likelihood of a locked door being mispositioned and other
administrative controls. Required Action A.3 is modified by
a Note that applies to air lock doors located in high
radiation areas and allows these doors to be verified locked
closed by use of administrative means. Allowing
verification by administrative means is considered
acceptable, since access to these areas is typically
restricted. Therefore, the probability of misalignment of
the door, once it has been verified to be in the proper
position, is small.
The Required Actions have been modified by two Notes.
Note 1 ensures that only the Required Actions and associated
Completion Times of Condition C are required if both doors
in the same air lock are inoperable. With both doors in the
same air lock inoperable, an OPERABLE door is not available
to be closed. Required Actions C.1 and C.2 are the
appropriate remedial actions. The exception to Note 1 does Containment Air Locks B 3.6.2 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.2-5Revision 2 not affect tracking the Completion Time from the initial entry into Condition A; only the requirement to comply with
the Required Actions. Note 2 allows use of the air lock for
entry and exit for seven days under administrative controls if both air locks have an inoperable door. This seven day restriction begins when the second air lock is discovered
inoperable. Containment entry may be required to perform Technical SpecificationsSurveillances and Required Actions, as well as other activities on equipment inside the C ontainment Structure that are required by T echnical S pecifications or activities on equipment that support T echnical S pecifications-required equipment. This Note is not intended to preclude performing other activities (i.e., non-T echnical S pecifications-required activities) if the C ontainment Structure was entered, using the inoperable air lock, to perform an allowed activity listed above. This
allowance is acceptable due to the low probability of an
event that could pressurize the C ontainment Structure during the short time that the OPERABLE door is expected to be
open.B.1, B.2, and B.3 With an air lock interlock mechanism is inoperable in one or more air locks, the Required Actions and associated Completion Times are consistent with those specified in
Condition A.
The Required Actions have been modified by two Notes.
Note 1 ensures that only the Required Actions and associated
Completion Times of Condition C are required if both doors
in the same air lock are inoperable. With both doors in the
same air lock inoperable, an OPERABLE door is not available
to be closed. Required Actions C.1 and C.2 are the
appropriate remedial actions. Note 2 allows entry into and
exit from the C ontainment Structure under the control of a dedicated individual stationed at the air lock
, to ensure that only one door is opened at a time (i.e., the individual
performs the function of the interlock).
Required Action B.3 is modified by a Note that applies to air lock doors located in high radiation areas and allows
these doors to be verified locked closed by use of Containment Air Locks B 3.6.2 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.2-6Revision 2 administrative means. Allowing verification by administrative means is considered acceptable, since access
to these areas is typically restricted. Therefore, the
probability of misalignment of the door, once it has been
verified to be in the proper position, is small.
C.1, C.2, and C.3 With one or more air locks inoperable for reasons other than those described in Condition s A or B, Required Action C.1 requires action to be initiated immediately to evaluate
previous combined leakage rates using current air lock test
results. An evaluation is acceptable since it is overly
conservative to immediately declare the C ontainment Structure inoperable if both doors in an air lock have failed a seal test or if the overall air lock leakage is not
within limits. In many instances (e.g., only one seal per
door has failed), the C ontainment Structure remains OPERABLE, yet only one hour (per LCO 3.6.1) would be provided to restore the air lock door to OPERABLE status
prior to requiring a plant shutdown. In addition, even with
both doors failing the seal test, the overall containment
leakage rate can still be within limits.
Required Action C.2 requires that one door in the affected containment air lock must be verified to be closed. This
action must be completed within the one hour Completion Time. This specified time period is consistent with the
ACTIONS of LCO 3.6.1, which requires that the C ontainment Structure be restored to OPERABLE status within one hour.Additionally, the affected air lock(s) must be restored to
OPERABLE status within the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Completion Time. The
specified time period is considered reasonable for restoring
an inoperable air lock to OPERABLE status, assuming that at
least one door is maintained closed in each affected air
lock.D.1 and D.2 If the inoperable containment air lock cannot be restored to OPERABLE status within the required Completion Time, the
plant must be brought to a MODE in which the LCO does not
apply. To achieve this status, the plant must be brought to Containment Air Locks B 3.6.2 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.2-7Revision 2 at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant
conditions from full power conditions in an orderly manner
and without challenging plant systems.SURVEILLANCESR 3.6.2.1 REQUIREMENTS Maintaining containment air locks OPERABLE requires
compliance with the leakage rate test requirements of the
Containment Leakage Rate Testing Program. This SR reflects
the leakage rate testing requirements with regard to air
lock leakage (Type B leakage tests). The acceptance
criteria were established during initial air lock and the C ontainment Structure OPERABILITY testing. The periodic testing requirements verify that the air lock leakage does
not exceed the allowed fraction of the overall containment
leakage rate. The Frequency is required by the Containment
Leakage Rate Testing Program.
The SR has been modified by two Notes. Note 1 states that an inoperable air lock door does not invalidate the previous
successful performance of the overall air lock leakage test.
This is considered reasonable since either air lock door is
capable of providing a fission product barrier in the event
of a DBA. Note 2 has been added to this SR requiring the
results to be evaluated against the acceptance criteria of
which is applicable to SR 3.6.1.1. This ensures that air
lock leakage is properly accounted for in determining the
combined Type s B and C containment leakage rate.
SR 3.6.2.2 The air lock interlock is designed to prevent simultaneous
opening of both doors in a single air lock. Since both the
inner and outer doors of an air lock are designed to
withstand the maximum expected post
-accident containment pressure, closure of either door will support the C ontainment Structure OPERABILITY. Thus, the door interlock feature supports the C ontainment Support OPERABILITY while the air lock is being used for personnel transit into and
out of the C ontainment Structure. Periodic testing of this interlock demonstrates that the interlock will function as Containment Air Locks B 3.6.2 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.2-8Revision 2 designed and that simultaneous opening of the inner and outer doors will not inadvertently occur. Due to the purely
mechanical nature of this interlock, and given that the
interlock mechanism is not normally challenged when the air
lock is used for entry and exit (procedures require strict
adherence to single door opening), this test is only
required to be performed every 24 months. The 24 month
Frequency is based on the need to perform this s urveillance test under the conditions that apply during a plant outage and the potential for loss of the C ontainment Structure OPERABILITY if the s urveillance test w as performed with the reactor at power. The 24 month Frequency for the interlock
is justified based on generic operating experience. The
24 month Frequency is based on engineering judgment and is
considered adequate given that the interlock is not
challenged during use of the air lock.
REFERENCES 1.UFSAR Containment Isolation Valves B 3.6.3 B 3.6 CONTAINMENT SYSTEMS B 3.6.3 Containment Isolation Valves
BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-1 Revision 2 BACKGROUND The containment isolation valves form part of the containment pressure boundary. They provide a means for fluid penetrations (not serving accident consequence limiting systems
) to be provided with two isolation barriers that are closed on an automatic isolation signal. These isolation devices are either passive or active (automatic).
Manual valves, de-activated automatic valves secured in
their closed position (including check valves with flow
through the valve secured), blind flanges, and closed
systems are considered passive devices. Check valves, or
other automatic valves designed to close without operator
action following an accident, are considered active devices.
Two barriers in series are provided for each penetration so
that no single credible failure or malfunction of an active
component can result in a loss of isolation or leakage that
exceeds limits assumed in the safety analysis. One of these
barriers may be a closed system. Containment isolation occurs upon receipt of a high containment pressure signal. The containment isolation signalcloses automatic containment isolation valves in fluid penetrations
, not required for operation of Engineered Safety Feature (ESF) systems , in order to prevent leakage of radioactive material. Upon actuation of safety injection, automatic containment isolation valves also isolate systems
not required for the C ontainment Structure or Reactor Coolant System (RCS) heat removal. Other penetrations are
isolated by the use of valves in the closed position or
blind flanges. As a result, the containment isolation
valves (and blind flanges) help ensure that the containment
atmosphere will be isolated in the event of a release of
radioactive material to containment atmosphere from the RCS following aDBA
. The OPERABILITY requirements for containment isolation valves help ensure that the C ontainment Structure is isolated within the time limits assumed in the safety analysis. Therefore, the OPERABILITY requirements provide
assurance that the C ontainment Structure function assumed in the accident analysis will be maintained.
Containment Isolation Valves B 3.6.3 BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-2 Revision 32 APPLICABLE The containment isolation valve LCO was derived from the SAFETY ANALYSES assumptions related to minimizing the loss of reactor coolant inventory and establishing the containment boundary
during major accidents. As part of the containment
boundary, containment isolation valve OPERABILITY supports leak tightness of the Containment Structure. Therefore, the safety analysis of any event requiring isolation of the
Containment Structure is applicable to this LCO. The DBAs that result in a release of radioactive material within the Containment Structure are a LOCA, a main SLB, and
a CEA ejection accident. In the analysis for each of these
accidents, it is assumed that containment isolation valves
are either closed or function to close within the required
isolation time following event initiation. This ensures
that potential paths to the environment through containment
isolation valves (including containment purge valves) are
minimized. The safety analysis assumes that the purge
valves are closed at event initiation. The DBA analysis assumes that, within 60 seconds after the accident, isolation of the Containment Structure is complete
and leakage terminated except for the design leakage rate, L a. The containment isolation total response time of 60 seconds includes signal delay, diesel generator startup (for loss of offsite power), and containment isolation valve
stroke times. The containment isolation valves satisfy 10 CFR 50.36(c)(2)(ii), Criterion 3. LCO Containment isolation valves form a part of the Containment Structure boundary. The containment isolation valve safety
function is related to minimizing the loss of reactor
coolant inventory and establishing the Containment Structure
boundary during a DBA.
The valves covered by this LCO are listed in Reference 1. The automatic power operated isolation valves are required to have isolation times within limits and to actuate on an
automatic isolation signal. The se valvesare listed with their associated stroke times in Reference
- 2.
Containment Isolation Valves B 3.6.3 BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-3 Revision 2 The normally closed isolation valves are considered OPERABLE when manual valves are closed, automatic valves are de-activated and secured in their closed position, blind
flanges are in place, and closed systems are intact. These
passive isolation valves or devices are those listed in Reference 1. This LCO provides assurance that the containment isolation valves will perform their designed safety functions to minimize the loss of reactor coolant inventory and establish the C ontainment Structure boundary during accidents. APPLICABILITY In MODE s 1, 2, 3, and 4, a DBA could cause a release of radioactive material to the C ontainment Structure. In MODE s 5 and 6, the probability and consequences of these events are reduced due to the pressure and temperature limitations of these MODE
- s. Therefore, the containment isolation valves are not required to be OPERABLE in MODE 5.
The requirements for containment isolation valves during MODE 6 are addressed in LCO 3.9.3
.ACTIONS The ACTIONS are modified by a Note allowing penetration flow paths to be unisolated intermittently under administrative controls. These administrative controls consist of stationing a dedicated operator at the valve controlswho is in continuous communication with the C ontrol R oom. In this way, the penetration can be rapidly isolated when a need for containment isolation is indicated. A second Note has been added to provide clarification that, for this LCO, separate Condition entry is allowed for each
penetration flow path. This is acceptable, since the
Required Actions for each Condition provide appropriate
compensatory actions for each inoperable containment
isolation valve. Complying with the Required Actions may
allow for continued operation, and subsequent inoperable
containment isolation valves are governed by subsequent
Condition entry and application of associated Required
Actions. The ACTIONS are further modified by a third Note, which ensures that appropriate remedial actions are taken, if Containment Isolation Valves B 3.6.3 BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-4 Revision 2 necessary, if the affected systems are rendered inoperable by an inoperable containment isolation valve. The fourth Note has been added that requires entry into the applicable Conditions and Required Actions of LCO 3.6.1
, when leakage results in exceeding the overall containment leakage limit. The fifth Note allows the shutdown coolingisolation valves to be opened when RCS temperature is 300 F to establish shutdown cooling flow. This Note is required for Operation in MODE 4 to allow shutdown cooling to be established. A.1 and A.2 In the event one containment isolation valve in one or more penetration flow paths is inoperable, the affected penetration flow path must be isolated. The method of
isolation must include the use of at least one isolation
barrier that cannot be adversely affected by a single active
failure. Isolation barriers that meet this criterion are a
closed and de-activated automatic containment isolation
valve, a closed manual valve, a blind flange, and a check
valve with flow through the valve secured. For penetrations
isolated in accordance with Required Action A.1, the device
used to isolate the penetration should be the closest
available one to the C ontainment Structure. Required Action A.1 must be completed within the four hour Completion Time. The four hour Completion Time is reasonable, considering the time required to isolate the penetration and
the relative importance of supporting the C ontainment Structure OPERABILITY during MODE s 1, 2, 3, and 4. For affected penetration flow paths that cannot be restored to OPERABLE status within the four hour Completion Time and that have been isolated in accordance with Required Action A.1, the affected penetration flow paths must be verified to be isolated on a periodic basis. This is
necessary to ensure that containment penetrations required
to be isolated following an accident and no longer capable
of being automatically isolated
, will be in the isolation position should an event occur. This Required Action does
not require any testing or device manipulation. Rather, it Containment Isolation Valves B 3.6.3 BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-5 Revision 2 involves verification, through a system walkdown, that those isolation devices outside the C ontainment Structure and capable of being mispositioned are in the correct position.
The Completion Time of "once per 31 days for isolation
devices outside C ontainment" is appropriate considering the fact that the devices are operated under administrative controls and the probability of their misalignment is low.
For the isolation devices inside the C ontainment Structure
, the time period specified as "prior to entering MODE 4 from
MODE 5 if not performed within the previous 92 days" is
based on engineering judgment and is considered reasonable
in view of the inaccessibility of the isolation devices and
other administrative controls that will ensure that
isolation device misalignment is an unlikely possibility. Condition A has been modified by a Note indicating that this Condition is only applicable to those penetration flow paths
with two containment isolation valves and not a closed
system. For penetration flow paths with one or more
containment isolation valves and a closed system, Condition C provides appropriate actions. Required Action A.2 is modified by a Note that applies to isolation devices located in high radiation areas and allows
these devices to be verified closed by use of administrative
means. Allowing verification by administrative means is
considered acceptable, since access to these areas is
typically restricted. Therefore, the probability of
misalignment of these devices, once they have been verified
to be in the proper position, is small.
B.1 With two containment isolation valves in one or more penetration flow paths inoperable, the affected penetration flow path must be isolated within one hour. The method of isolation must include the use of at least one isolation barrier that cannot be adversely affected by a single active
failure. Isolation barriers that meet this criterion are a
closed and de-activated automatic valve, a closed manual
valve, and a blind flange. The one hour Completion Time is consistent with the ACTIONS of LCO 3.6.1. In the event the
affected penetration is isolated in accordance with Required Containment Isolation Valves B 3.6.3 BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-6 Revision 2 Action B.1, the affected penetration must be verified to be isolated on a periodic basis per Required Action A.2, which
remains in effect. This periodic verification is necessary
to assure leak tightness of the C ontainment Structure and that penetrations requiring isolation following an accident
are isolated. The Completion Time of once per 31 days for verifying each affected penetration flow path is isolated
, is appropriate
, considering the fact that the valves are operated under administrative controls and the probability of their misalignment is low. Condition B is modified by a Note indicating this Condition is only applicable to penetration flow paths with two
containment isolation valves. Condition A of this LCO
addresses the condition of one containment isolation valve
inoperable in this type of penetration flow path. C.1 and C.2 Withone or more containment isolation valves inoperable in one or more penetration flow paths , the inoperable valves must be restored to OPERABLE status or the affected
penetration flow path must be isolated. The method of
isolation must include the use of at least one isolation
barrier that cannot be adversely affected by a single active
failure. Isolation barriers that meet this criterion are a
closed and de-activated automatic valve, a closed manual
valve, and a blind flange. A check valve may not be used to
isolate the affected penetration. Required Action C.1 must
be completed within the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time. The
specified time period is reasonable, considering the
relative stability of the closed system (hence, reliability)
to act as a penetration isolation boundary and the relative
importance of supporting the C ontainment Structure OPERABILITY during MODE s 1, 2, 3, and 4. In the event the affected penetration is isolated in accordance with Required
Action C.1, the affected penetration flow path must be
verified to be isolated on a periodic basis. This is
necessary to assure leak tightness of the C ontainment Structure and that containment penetrations requiring isolation following an accident are isolated. The
Completion Time of once per 31 days for verifying that each
affected penetration flow path is isolated
, is appropriate Containment Isolation Valves B 3.6.3 BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-7 Revision 32 considering the valves are operated under administrative controls and the probability of their misalignment is low. Condition C is modified by a Note indicating that this Condition is only applicable to those penetration flow paths with one or more containment isolation valves and a closed system. This Note is necessary since this Condition is written to specifically address those penetration flow paths
in a closed system. Containment isolation valves and their
associated penetration numbers are given in Reference 1
.The penetrations with closed systems are listed below.
Penetration No.Function 1B Containment Vent Header to Waste Gas 16 Component Cooling Water Inlet 17A Steam Generator Surface Blowdown 17B Steam Generator Surface Blowdown 18 Component Cooling Water Outlet 19A Instrument Air 20A Nitrogen Supply 20B Nitrogen Supply 20C Nitrogen Supply 21 Auxiliary Feedwater 22 Auxiliary Feedwater 23 Reactor Coolant Drain Tank Drains 24 Oxygen Sample Line 25 Service Water Inlet 26 Service Water Inlet 27 Service Water Inlet 28 Service Water Inlet 29 Service Water Return 30 Service Water Return 31 Service Water Return 32 Service Water Return 33 Main Feedwater 34 Main Feedwater 35 Main Steam 36 Main Steam 38 Demineralized Water 43A Steam Generator Bottom Blowdown 43B Steam Generator Bottom Blowdown 44 Fire Protection Containment Isolation Valves B 3.6.3 BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-8 Revision 32 Required Action C.2 is modified by a Note that applies to valves and blind flanges, located in high radiation areas, and allows these devices to be verified closed by use of
administrative means. Allowing verification by
administrative means is considered acceptable, since access to these areas is typically restricted. Therefore, the probability of misalignment of these valves, once they have
been verified to be in the proper position, is small. D.1 and D.2 If the Required Actions and associated Completion Times are not met, the plant must be brought to a MODE in which the
LCO does not apply. To achieve this status, the plant must
be brought to at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5
within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are
reasonable, based on operating experience, to reach the
required plant conditions from full power conditions in an orderly manner and without challenging plant systems. SURVEILLANCE SR 3.6.3.1 REQUIREMENTS This SR ensures that the containment vent valves are closed as required, or, if open, open for an allowable reason. If
a containment vent valve is open in violation of this SR, the valve is considered inoperable. If the inoperable valve
is not otherwise known to have excessive leakage when
closed, it is not considered to have leakage outside of
limits. The SR is not required to be met when the
containment vent valves are open for pressure control, ALARA or air quality considerations for personnel entry, or for surveillance tests that require the valves to be open. The
containment vent valves are capable of closing in the
environment, following a LOCA. Therefore, these valves are
allowed to be open for limited periods of time. The 31 day
Frequency is consistent with other containment isolation
valve requirements discussed in SR 3.6.3.2. SR 3.6.3.2 This SR requires verification that each containment isolation manual valve and blind flange located outside the
Containment Structure, and not locked, sealed, or otherwise Containment Isolation Valves B 3.6.3 BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-9 Revision 32 secured, and required to be closed during accident conditions is closed. The SR helps to ensure that post-
accident leakage of radioactive fluids or gases outside the
containment boundary is within design limits. This SR does
not require any testing or valve manipulation. Rather, it
involves verification, through a system walkdown, that those containment isolation valves outside the Containment Structure and capable of being mispositioned are in the
correct position. Since verification of valve position for
containment isolation valves outside the Containment
Structure is relatively easy, the 31 day Frequency is based
on engineering judgment, and was chosen to provide added
assurance of the correct positions. Containment isolation
valves that are open under administrative controls are not
required to meet the SR during the time the valves are open.
This SR does not apply to valves that are locked, sealed, or
otherwise secured in the closed position, since these were
verified to be in the correct position upon locking, sealing, or securing. The Note applies to valves and blind flanges located in high radiation areas and allows these devices to be verified
closed by use of administrative means. Allowing
verification by administrative means is considered
acceptable, since access to these areas is typically
restricted during MODEs 1, 2, 3, 4 and for ALARA reasons.
Therefore, the probability of misalignment of these
containment isolation valves, once they have been verified
to be in the proper position, is small. SR 3.6.3.3 This SR requires verification that each containment isolation manual valve and blind flange located inside the
Containment Structure, and not locked, sealed, or otherwise secured, and required to be closed during accident conditions is closed. The SR helps to ensure that post-
accident leakage of radioactive fluids or gases outside the
containment boundary is within design limits. For
containment isolation valves inside the Containment
Structure, the Frequency of "prior to entering MODE 4 from
MODE 5 if not performed within the previous 92 days" is
appropriate, since these containment isolation valves are
operated under administrative controls and the probability Containment Isolation Valves B 3.6.3 BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-10 Revision 32 of their misalignment is low. Containment isolation valves that are open under administrative controls are not required
to meet the SR during the time that they are open. This SR
does not apply to valves that are locked, sealed, or
otherwise secured in the closed position, since these were
verified to be in the correct position upon locking, sealing, or securing. The Note allows valves and blind flanges located in high radiation areas to be verified closed by use of administrative means. Allowing verification by
administrative means is considered acceptable, since access
to these areas is typically restricted during MODEs 1, 2, and 3 for ALARA reasons. Therefore, the probability of
misalignment of these containment isolation valves, once
they have been verified to be in their proper position, is
small. SR 3.6.3.4 Verifying that the isolation time of each automatic power operated containment isolation valve is within limits is
required to demonstrate OPERABILITY. The isolation time
test, ensures the valve will isolate in a time period less
than or equal to that assumed in the safety analysis. The
isolation time and Frequency of this SR are in accordance
with the Inservice Testing Program.
The isolation time limits are contained in Reference 2. SR 3.6.3.5 Automatic containment isolation valves close on an isolation signal [containment isolation signal Channels A or B, or
safety injection actuation signal (SIAS) Channels A or B] to
prevent leakage of radioactive material from the Containment
Structure following a DBA. This SR ensures each automatic containment isolation valve will actuate to its isolation position on a containment isolation actuation signal. This
surveillance test is not required for valves that are
locked, sealed, or otherwise secured in the required
position under administrative controls. The 24 month
Frequency was developed considering it is prudent that this
SR be performed only during a unit outage, since isolation
of penetrations would eliminate cooling water flow and Containment Isolation Valves B 3.6.3 BASESCALVERT CLIFFS - UNITS 1 & 2 B 3.6.3-11 Revision 32 disrupt normal operation of many critical components.
Operating experience has shown that these components usually
pass this SR when performed on the 24 month Frequency.
Therefore, the Frequency was concluded to be acceptable from a reliability standpoint. REFERENCES 1. UFSAR, Chapter 5, "Structures" , Figure 5-10 2. UFSAR, Chapter 5, "Structures", Table 5-3 Containment Pressure B 3.6.4 B 3.6 CONTAINMENT SYSTEMS B 3.6.4 Containment Pressure
BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.4-1Revision 2BACKGROUNDThe containment pressure is limited during normal operation to preserve the initial conditions assumed in the accidentanalyses for aLOCAor main SLB. These limits also prevent the containment pressure from exceeding the containment
design negative pressure differential
, with respect to the outside atmosphere in the event of the C ontainment Structure being sealed during low barometric pressure and high
temperature, then being exposed to a concurrent cooling of
containment atmosphere and a barometric pressure rise.
Containment pressure is a process variable that is monitored and controlled. The containment pressure limits are derived
from the input conditions used in the containment functional
analyses and the containment structure external pressure
analysis. Should operation occur above the upper limits coincident with aDBA
, post-accident containment pressures could exceed calculated values. Should containment closure
or integrity be set below the lower limits, the external
pressure limits may be exceeded during barometric pressure
changes.APPLICABLEContainment internal pressure is an initial condition used SAFETY ANALYSESin the DBA analyses to establish the maximum peak containment internal pressure. The limiting DBA considered
for determining the maximum containment internal pressure is
RATED THERMAL POWER and + 1.8 psig initial containment pressure results in the highest
calculated internal containment pressure (P a)below the internal design pressure of 50.0 psig. The postulated DBAs are analyzed assuming degraded containmentESFsystems (i.e., assuming the loss of one ESF bus, which is the worst
case single active failure, resulting in one train of the
c ontainment sprayand one train of the c ontainment coolers being rendered inoperable). It is this maximum containment
pressure that is used to ensure that the licensing basis
dose limitations are met.
The initial pressure condition used in the containmentanalysis was 16.5 psia (1.8 psig).The LCO limit of 1.8 psig ensures that, in the event of an accident, the Containment Pressure B 3.6.4 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.4-2Revision 2 maximum accident design pressure for the C ontainment Structure , 50 psig, is not exceeded. If a LOCA occurred while the containment internal pressure was at the LCO valueof 1.8 psig, a total pressurebelow the design value of 50 psig would result
.Containment pressure satisfies 10 CFR 50.36(c)(2)(ii),
Criterion 2.LCOMaintaining containment pressure less than or equal to the LCO upper pressure limit ensures that, in the event of a
DBA, the resultant peak containment accident pressure will
remain below the containment design pressure. Maintaining
containment pressure greater than or equal to the LCO lower
pressure limit
, ensures that the C ontainment Structure will not exceed the design negative pressure differential
following the inadvertent actuation of c ontainment s pray.APPLICABILITYIn MODE s 1, 2, 3, and 4, a DBA could cause a release of radioactive material to the C ontainment Structure. Since maintaining containment pressure within limits is essential
to ensure initial conditions assumed in the accident
analysis are maintained, the LCO is applicable in MODE s 1, 2, 3, and 4.
In MODE s 5 and 6, the probability and consequences of these events are reduced due to the pressure and temperature limitations of these MODE
- s. Therefore, maintaining containment pressure within the limits of the LCO is not
required in MODE s 5 or 6.ACTIONSA.1 When containment pressure is not within the limits of the
LCO, containment pressure must be restored to within these
limits , within one hour. The Required Action is necessary to return operation to within the bounds of the containment
analysis. The one hour Completion Time is consistent withthe ACTIONS of LCO 3.6.1which requires that the C ontainment Structure be restored to OPERABLE status within one hour.
Containment Pressure B 3.6.4 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.4-3Revision 2 B.1 and B.2 If containment pressure cannot be restored to within limits within the required Completion Time, the plant must be
brought to a MODE in which the LCO does not apply. To
achieve this status, the plant must be brought to at least
MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The
allowed Completion Times are reasonable, based on operating
experience, to reach the required plant conditions from full
power conditions in an orderly manner
, and without challenging plant systems.SURVEILLANCESR 3.6.4.1 REQUIREMENTS Verifying that containment pressure is within limits ensures
that operation remains within the limits assumed in the
accident analysis. The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Frequency of this SR was
developed after taking into consideration operating
experience related to trending of containment pressure
variations during the applicable MODE
- s. Furthermore, the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Frequency is considered adequate in view of other
indications available in the C ontrol R oom, including alarms, to alert the operator to an abnormal containment pressure
condition.REFERENCESNone Containment Air Temperature B 3.6.5 B 3.6 CONTAINMENT SYSTEMS B 3.6.5 Containment Air Temperature
BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.5-1Revision 2BACKGROUNDThe C ontainment S tructure serves to contain radioactive material that may be released from the reactor corefollowing aDBA
. The C ontainment Structure average air temperature is limited during normal operation to preserve
the initial conditions assumed in the accident analyses for aLOCAor mainSLB
.The containment average air temperature limit is derived
from the input conditions used in the containment functional
analyses and the C ontainment S tructure external pressure analyses. This LCO ensures that initial conditions assumed
in the analysis of containment response to a DBA
, are not violated during unit operations. The total amount of energy
to be removed from C ontainment Structure by the c ontainment s pray and containment coolingduring post
-accident conditions is dependent on the energy released to the
C ontainment Structure due to the event, as well as the initial containment temperature and pressure. The higher
the initial temperature, the more energy that must be
removed, resulting in a higher peak containment pressure and
temperature. Exceeding containment design pressure may
result in leakage greater than that assumed in the accident
analysis (Reference 1). Operation with containment
temperature in excess of the LCO limit violates an initial
condition assumed in the accident analysis.APPLICABLEContainment average air temperature is an initial condition SAFETY ANALYSESused in the DBA analyses that establishes the containment environmental qualification operating envelope for both
pressure and temperature. The limit for containment average
air temperature ensures that operation is maintained within
the assumptions used in the DBA analysis for C ontainment.
The accident analyses and evaluations considered both LOCAs
and main SLBs for determining the maximum peak containment pressures and temperatures. The worst case LOCA generates
larger mass and energy releases than the worst case main SLB. Thus, the LOCA event bounds the main SLB event from the containment peak pressure and temperature standpoint.
The initial pre-accident temperature inside the C ontainment Structure was assumed to be 120°F (Reference 1).
Containment Air Temperature B 3.6.5 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.5-2Revision 2 The initial containment average air temperature condition of 120°F resulted in a maximum vapor temperature described in Reference 1. The consequence of exceeding the design temperature for extended periods may be the potential for degradation of the containment structure under accident loads.Containment average air temperature satisfies
10 CFR 50.36(c)(2)(ii), Criterion 2.LCODuring a DBA, with an initial containment average air temperature less than or equal to the LCO temperature limit, the resultant peak accident temperature is maintained below
the containment design temperature. As a result, the
ability of the C ontainment Structure to perform its function is ensured.APPLICABILITYIn MODE s 1, 2, 3, and 4, a DBA could cause a release of radioactive material to the C ontainment Structure. In MODE s 5 and 6, the probability and consequences of these events are reduced due to the pressure and temperature
limitations of these MODE
- s. Therefore, maintaining containment average air temperature within the limit is not
required in MODE s 5 or 6.ACTIONSA.1 When containment average air temperature is not within the
limit of the LCO, it must be restored to within limit
, within eight hours. This Required Action is necessary to return operation to within the bounds of the containment
analysis. The eight hour Completion Time is acceptable considering the sensitivity of the analysis to variations in
this parameter and provides sufficient time to correct minor
problems.B.1 and B.2 If the containment average air temperature cannot be restored to within its limit
, within the required Completion Time, the plant must be brought to a MODE in which the LCO
does not apply. To achieve this status, the plant must be
brought to at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 Containment Air Temperature B 3.6.5 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.5-3Revision 3 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the
required plant conditions from full power conditions in an
orderly manner and without challenging plant systems.SURVEILLANCESR 3.6.5.1 REQUIREMENTS Verifying that containment average air temperature is within
the LCO limit ensures that containment operation remains
within the limit assumed for the containment analyses. In
order to determine the containment average air temperature, an arithmetic average is calculated using measurements taken
from the containment dome
[1(2)-TI-5309]
and the containment reactor cavity
[1(2)-TI-5311]
temperature indicators selected to provide a representative sample of the overall
containment atmosphere. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency of this SR is
considered acceptable based on the observed slow rates of
temperature increase within the Containment Structure as a
result of environmental heat sources (due to the large
volume of the Containment Structure). Furthermore, the
24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is considered adequate in view of other
indications available in the Control Room, including alarms, to alert the operator to an abnormal containment temperature
condition.REFERENCES1.UFSAR, Section 14.20, "Containment Response" Containment Spray and Cooling Systems B 3.6.6 B 3.6 CONTAINMENT SYSTEMS B 3.6.6 Containment Spray and Cooling Systems BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.6-1Revision 2BACKGROUNDThe Containment Spray andCooling S ystems provide containment atmosphere cooling to limit post
-accident pressure and temperature in theC ontainment Structure to less than the design values. Reduction of containment pressure and the iodine removal capability of the spray
, reduce the release of fission product radioactivity from the C ontainment Structure to the environment, in the event of a DBA , to within limits. The Containment Spray andCooling Systems are designed to the requirements inReference 1
, Appendix 1C, Criteria, 58, 59, 60, 61, 62, 63, 64, and 65
.The Containment Spray and Cooling System sareESFsystems.
They are designed to ensure that the heat removal capability
required during the post
-accident period can be attained.The Containment SprayandCooling System s provide redundant methods to limit and maintain post
-accident conditions to less than the containment design values.
Containment Spray System The Containment Spray System consists of two separate trains of equal capacity, each of sufficient capacity to supply
approximately 50% of the design cooling requirement. Each
train includes a containment spray pump, spray headers, nozzles, valves, and piping. Each train is powered from a
separate ESF bus. The refueling water tank (RWT) supplies
borated water to the containment spray during the injection phase of operation. In the recirculation mode of operation, containment spray pump suction is transferred from the RWT
to the containment sump(s). Each spray system flow path
from the containment sump will be via an OPERABLE shutdown
cooling heat exchanger.
The Containment Spray System provides a spray of cold borated water into the upper regions of theC ontainment Structure to reduce containment pressure and temperature and to reduce the concentration of fission products in the
containment atmosphere during a DBA. The RWT solution
temperature is an important factor in determining the heat
removal capability of the Containment Spray System during
the injection phase. In the recirculation mode of Containment Spray and Cooling Systems B 3.6.6 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.6-2Revision 2 operation, heat is removed from the containment sump water by the shutdown cooling heat exchangers. Each train of the
Containment Spray System provides adequate spray coverage to meet 50% of the system design requirements for containment heat removal and 100% of the iodine removal design bases.
The Containment Spray System is actuated either automatically by a containment spray actuation signalcoincident with aSIASor manually. An automatic actuation starts the two c ontainment spraypumps, and begins the injection phase. The containment spray header isolation valves open upon a containment spray actuation signal. A manual actuation of the Containment Spray System is available on the main control board to begin the same
sequence. The injection phase continues until an RWT l ow level signal is received. The l ow level for the RWTgenerates a recirculation actuation signalthat aligns valves from the containment spray pump suction to the
containment sump. The Containment Spray System in
recirculation mode maintains an equilibrium temperature between the containment atmosphere and the recirculated sump water. Operation of the Containment Spray System in the
recirculation mode is controlled by the operator in
accordance with the E mergency O perating P rocedures.
Containment Cooling System Two trains of containment cooling, each of sufficient
capacity to supply approximately 67% of the design cooling requirement, are provided. Two trains with two fan units each are supplied with cooling water from a separate train
of service water cooling. Three of the four fans are
required to furnish the design cooling capacity. Air is
drawn into the coolers through the fans and discharged
throughouttheC ontainment Structure
.In post-accident operation following a SIAS, all four Containment Cooling System fans are designed to start automatically in slow speed. Cooling is supplied by the service water cooled coils. The temperature of the service
water is an important factor in the heat removal capability of the fan units.
Containment Spray and Cooling Systems B 3.6.6 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.6-3Revision 15APPLICABLEThe Containment Spray and Cooling Systems limit theSAFETY ANALYSEStemperature and pressure that could be experienced following a DBA. The limiting DBAs considered relative to containment temperature and pressure are LOCA and main SLB. The DBA, LOCA, and main SLB are analyzed using computer codes
designed to predict the resultant containment pressure and
temperature transients. No DBAs are assumed to occur
simultaneously or consecutively. The postulated DBAs are
analyzed with regard to containment ESF systems, assuming
the loss of one ESF bus, which is the worst case single
active failure, resulting in one train of the Containment Spray System and one train of the Containment Cooling System being rendered inoperable.
The analysis and evaluation show that under the worst case scenario, the highest peak containment pressure and
temperature are within the design. (See the Bases for
Specifications 3.6.4 and 3.6.5 for a detailed discussion.)
The analyses and evaluations assume a power level of
102% RATED THERMAL POWER, one containment spray train and one containment cooling train operating, and initial (pre-accident) conditions of 120°F and 16.5 psia. The
analyses also assumes a response time delayed initiation, in
order to provide a conservative calculation of peak
containment pressure and temperature responses.
The modeled Containment Spray System actuation from the containment analysis is based upon a response time associated with exceeding the Containment High-High pressure setpoint coincident with an SIAS to achieve full flow
through the containment spray nozzles. The Containment
Spray System total response time of 62.9 seconds for a main steam line break and 70.9 seconds for a LOCA, includes diesel generator startup (for loss of offsite power),
sequencing equipment onto the emergency bus, containment
spray pump startup, and spray line filling (Reference 1, Chapter 7).
The performance of the containment cooling train for post-accident conditions is given in Reference 1, Chapter 6. The
results of the analysis, is that each train can provide
approximately 67% of the required peak cooling capacity
during the post-accident condition. The train post-accident Containment Spray and Cooling Systems B 3.6.6 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.6-4Revision 15 cooling capacity under varying containment ambient conditions, required to perform the accident analyses, is
also shown in Reference 1, Chapter 6.
The modeled Containment Cooling System actuation from the containment analysis, is based upon the unit specific
response time associated with exceeding the SIAS to achieve
full Containment Cooling System air and safety grade cooling
water flow.
The Containment Spray and Cooling Systems satisfy 10 CFR 50.36(c)(2)(ii), Criterion 3.LCODuring a DBA, a minimum of one containment cooling train and one containment spray train, is required to maintain the containment peak pressure and temperature, below the design
limits (Reference 1, Chapter 6). Additionally, one
containment spray train is also required to remove iodine
from the containment atmosphere and maintain concentrations
below those assumed in the safety analysis. To ensure that
these requirements are met, two containment spray trains and
two containment cooling trains (all four coolers) must be
OPERABLE. Therefore, in the event of an accident, the minimum requirements are met, assuming that the worst case single active failure occurs.
Each Containment Spray System includes a spray pump, spray headers, nozzles, valves, piping, instruments, and controls
to ensure an OPERABLE flow path capable of taking suction
from the RWT upon an ESF actuation signal and automatically
transferring suction to the containment sump. Each spray system flow path from the containment sump will be via an OPERABLE shutdown cooling heat exchanger.
Each Containment Cooling System includes cooling coils, dampers, fans, instruments, and controls to ensure an OPERABLE flow path.APPLICABILITYIn MODEs 1, 2, and 3, a DBA could cause a release of radioactive material to the Containment Structure and an increase in containment pressure and temperature, requiring
the operation of the containment spray trains and containment cooling trains.
Containment Spray and Cooling Systems B 3.6.6 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.6-5Revision 2 The C ontainment S pray S ystem is only required to be OPERABLE in MODE 3 with pressurizer pressure 1750 psia.
In MODE 3 with pressurizer pressure
< 1750 psia, and in MODE s 4, 5, and 6, the probability and consequences of these events are reduced due to the pressure and temperature limitations of these MODE
- s. Thus, the Containment Spray System is not required to be OPERABLE in MODE 3 with pressurizer pressure
< 1750 psia, and the Containment Spray and Cooling Systems are not required to be OPERABLE in MODE s 4, 5, and 6.ACTIONSA.1 With one containment spray train inoperable, the inoperable containment spray train must be restored to OPERABLE status
within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. In this Condition, the remaining OPERABLE spray and cooling trains are adequate to perform the iodine removal and containment cooling functions. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />
Completion Time takes into account the redundant heat
removal capability afforded by the Containment Spray System, reasonable time for repairs, and the low probability of a
DBA occurring during this period.
The 10 day portion of the Completion Time for Required Action A.1 is based upon engineering judgment. It takes into account the low probability of coincident entry into
two Conditions in this Specification coupled with the low
probability of an accident occurring during this time.
Refer to S p ec ification 1.3,for a more detailed discussion of the purpose of the "from discovery of failure to meet the
LCO" portion of the Completion Time.
B.1 and B.2 If the inoperable containment spray train cannot be restored to OPERABLE status within the required Completion Time, the
plant must be brought to a MODE in which the LCO does not
apply. To achieve this status, the plant must be brought to
at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 3 with pressurizer pressure
< 1750 psia within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The allowed Completion Time of six hours is reasonable, based on operating experience, to reach MODE 3 from full power Containment Spray and Cooling Systems B 3.6.6 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.6-6Revision 2 conditions in an orderly manner
, and without challenging plant systems. The extended interval to reach MODE 3 with pressurizer pressure
< 1750 psia allows additional time for the restoration of the containment spray train and is reasonable when considering that the driving force for a
release of radioactive material from the RCS is reduced in MODE 3.C.1 With one required containment cooling train inoperable, the inoperable containment cooling train must be restored to
OPERABLE status within seven days. The remaining OPERABLE containment spray and cooling components provide iodine
removal capabilities and are capable of providing at least
100% of the heat removal needs after an accident. The
seven day Completion Time was developed taking into account the redundant heat removal capabilities afforded by combinations of the Containment SprayandCooling System s, and the low probability of a DBA occurring during this
period.The 10 day portion of the Completion Time for Required Action C.1 is based upon engineering judgment. It takes
into account the low probability of coincident entry into
two Conditions in this Specification coupled with the low
probability of an accident occurring during this time.
Refer to S p ec ifica tion 1.3 for a more detailed discussion of the purpose of the "from discovery of failure to meet the LCO" portion of the Completion Time.
D.1 With two required containment cooling trains inoperable, one of the required containment cooling trains must be restored
to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The remaining OPERABLE
containment spray components provide iodine removal capabilities and are capable of providing at least 100% of the heat removal needs after an accident. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />
Completion Time was developed taking into account the
redundant heat removal capabilities afforded by combinations of the Containment SprayandCooling System s , the iodine removal function of the Containment Spray System, and the
low probability of a DBA occurring during this period.
Containment Spray and Cooling Systems B 3.6.6 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.6-7Revision 2 E.1 and E.2 If the Required Actions and associated Completion Times of Condition s C or D of this LCO are not met, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least
MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 4 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The
allowed Completion Times are reasonable, based on operating
experience, to reach the required plant conditions from full
power conditions in an orderly manner and without
challenging plant systems.
F.1 With two containment spray trains or any combination ofthree or more Containment SprayandCooling System s trains inoperable, the unit is in a condition outside the accident analysis. Therefore, LCO 3.0.3 must be entered immediately.SURVEILLANCESR 3.6.6.1 REQUIREMENTS Verifying the correct alignment for manual, power
-operated, and automatic valves in the containment spray flow path provides assurance that the proper flow paths will exist for Containment Spray System operation. This SR does not apply to valves that are locked, sealed, or otherwise secured in
position since these were verified to be in the correct
position prior to being secured. This SR also does not
apply to valves that cannot be inadvertently misaligned, such as check valves. This SR does not require any testing
or valve manipulation. Rather, it involves verifying, through a system walkdown, that those valves outside the C ontainment Structure and capable of potentially being mispositioned are in the correct position.
SR 3.6.6.2 Starting each containment cooling train fan unit from the Control Room and operating it for 15 minutes ensures that all trains are OPERABLE and that all associated controls are functioning properly. It also ensures that blockage, fan or motor failure, or excessive vibration can be detected and
corrective action taken. The 31 day Frequency of this SR Containment Spray and Cooling Systems B 3.6.6 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.6-8Revision 2 was developed considering the known reliability of the fan units and controls, the two train redundancy available, and
the low probability of a significant degradation of the containment cooling train occurring between surveillances and has been shown to be acceptable through operating
experience.
SR 3.6.6.3 Verifying a service water flow rate of 2000 gpm to each cooling unit when the full flow service water outlet valves are fully open provides assurance that the design flow rate
assumed in the safety analyses will be achieved (Reference 1, Chapter 7
). Also considered in selecting this Frequency were the known reliability of the Service Water System, the two train redundancy, and the low probability of
a significant degradation of flow occurring between
surveillance test s.SR 3.6.6.4 Verifying that each containment spray pumps developed head
at the flow test point is greater than or equal to the
required developed head ensures that spray pump performance
has not degraded during the cycle. Flow and differential
pressure are normal tests of centrifugal pump performance required byReference
- 2. Since the containment spray pumps cannot be tested with flow through the spray headers, they are tested on recirculation flow. This test confirms one point on the pump design curve and is indicative of overall
performance. Such inservice inspections confirm component
OPERABILITY, trend performance, and detect incipient
failures by indicating abnormal performance. The Frequency
of this SR is in accordance with the Inservice Testing
Program.SR 3.6.6.5 and SR 3.6.6.6 These SRs verify that each automatic containment spray valve actuates to its correct position and that each containment
spray pump starts upon receipt of an actual or simulated
actuation signal (i.e., the appropriate Engineered Safety Feature Actuation Systemsignal). This S R is not required for valves that are locked, sealed, or otherwise secured in
the required position under administrative controls. The Containment Spray and Cooling Systems B 3.6.6 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.6-9Revision 18 24 month Frequency is based on the need to perform these surveillance tests under the conditions that apply during a
plant outage and the potential for an unplanned transient if the surveillance tests were performed with the reactor at power. Operating experience has shown that these components
usually pass the surveillance tests when performed at the
24 month Frequency. Therefore, the Frequency was concluded
to be acceptable from a reliability standpoint.
The surveillance test of containment sump isolation valves is also required by SR 3.5.2.5. A single surveillance test may be used to satisfy both requirements.
SR 3.6.6.7 This SR verifies that each containment cooling train actuates upon receipt of an actual or simulated actuation
signal (i.e., the appropriate Engineered Safety Feature
Actuation System signal). The 24 month Frequency is based
on engineering judgment and has been shown to be acceptable
through operating experience. See SR 3.6.6.5 and SR 3.6.6.6, above, for further discussion of the basis for the 24 month Frequency.
SR 3.6.6.8 With the containment spray inlet valves closed and the spray header drained of any solution, low pressure air or smoke
can be blown through check valve bonnets. Performance of
this SR demonstrates that each spray nozzle is unobstructed and provides assurance that spray coverage of the Containment Structure during an accident is not degraded.
Due to the passive design of the nozzle, a test after maintenance that could result in nozzle blockage is considered adequate. Maintenance that could result in nozzle blockage is generally loss of foreign material control or a flow of borated water through a nozzle. Should either of these events occur, a supervisory evaluation will be required to determine whether nozzle blockage is a possible result of the event
.
Containment Spray and Cooling Systems B 3.6.6 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.6-10Revision 18REFERENCES1.UFSAR2.American Society of Mechanical Engineers, Boiler and Pressure Vessel Code,Section XI, Rules for In-Service Inspection of Nuclear Power Plant Components IRS B 3.6.8 B 3.6 CONTAINMENT SYSTEMS B 3.6.8 Iodine Removal System (IRS)
BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.8-1Revision 2BACKGROUNDThe IRS is provided perReference 1 , Appendix 1C,Criteria62, 63, and 64 , to reduce the concentration of fission products released to the containment atmosphere following a postulated accident. The IRS would function
together with the Containment Spray and Cooling S ystemsfollowing aDBAto reduce the potential release of radioactive material, principally iodine, from the
C ontainment Structure to the environment.
The IRS consists of three 50% capacity separate, independent (except for power), and redundant trains. Each train
includes a moisture separator, a high efficiency particulate airfilter, an activated charcoal adsorber section for removal of radioiodines, a fan, and instrumentation. The
moisture separators function to reduce the moisture content of the airstream. The system initiates filtered recirculation of the containment atmosphere following
receipt of a SIAS. The system design is described in Reference 1, Section 6.7
.The moisture separator is included for moisture (free water)
removal from the gas stream. The moisture separator is
important to the effectiveness of the charcoal adsorbers.
Three IRS trains are provided to meet the requirement for separation, independence (except for power), and redundancy.
Two trains of the IRS are powered by separate ESF buses.The third IRS train is a swing train that can be aligned to
take power from either ESFs bus.APPLICABLEThe DBAs that result in a release of radioactive iodine SAFETY ANALYSESwithin the C ontainment Structureare aLOCA , a mainSLB
, oraCEAejection accident. In the analysis for each of these accidents, it is assumed that adequate containment leak
tightness exists at event initiation to limit potential leakage to the environment. Additionally, it is assumed
that the amount of radioactive iodine release is limited by
reducing the iodine concentration in the containment
atmosphere.
IRS B 3.6.8 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.8-2Revision 2 The IRS design basis is established by the consequences of the limiting DBA, which is a LOCA. The accident analysis (Reference 1, Section 14.21) assumes that only two trains of the IRS are functional due to a single failure that disables
the other train. The accident analysis accounts for the
reduction in airborne radioactive iodine provided by the
remaining two trains of this filtration system.
The IRS satisfies 10 CFR 50.36(c)(2)(ii), Criterion 3.LCOThree separate, independent (except for power), and redundant trains of the IRS are required to ensure that at least two are available, assuming a single failure
coincident with a loss of offsite power.APPLICABILITYIn MODE s 1, 2, 3, and 4, iodine is a fission product that can be released from the fuel to the reactor coolant as a
result of a DBA. The DBAs that can cause a failure of the
fuel cladding are a LOCA, main SLB, and CEA ejection accident. Because these accidents are considered credible
accidents in MODE s 1, 2, 3, and 4, the IRS must be operable in these MODE s to ensure the reduction in iodine concentration assumed in the accident analysis.
In MODE s 5 and 6, the probability and consequences of a LOCA are low due to the pressure and temperature limitations of these MODE
- s. The IRS is not required in these MODE s to remove iodine from the containment atmosphere.ACTIONSA.1 With one IRS train inoperable, the inoperable train must be
restored to OPERABLE status within seven days. The components in this degraded condition are capable of
providing 100% of the iodine removal needs after a DBA. The
seven day Completion Time is based on consideration of such factors as:a.The availability of the OPERABLE redundant IRS train; b.The fact that, even with no IRS train in operation, almost the same amount of iodine would be removed from the containment atmosphere through absorption by the
Containment Spray System; and IRS B 3.6.8 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.8-3Revision 2c.The fact that the Completion Time is adequate to make most repairs.
B.1 If two IRS trains are inoperable, one must be restored to OPERABLE status within one hour. The one hour Completion
Time allows the swing train to be aligned to the appropriate
bus to ensure each of the two remaining trains are powered
from separate and independent buses. The one hour
, also allows time to restore one train to OPERABLE status prior to
initiating a plant shutdown. This is reasonable considering
that a plant shutdown is a plant transient.
C.1 and C.2 If the IRS train cannot be restored to OPERABLE status within the required Completion Time, the plant must be
brought to a MODE in which the LCO does not apply. To
achieve this status, the plant must be brought to at least
MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The
allowed Completion Times are reasonable, based on operating
experience, to reach the required plant conditions from full
power conditions in an orderly manner and without
challenging plant systems.SURVEILLANCESR 3.6.8.1 REQUIREMENTS Initiating each IRS train from the Control Room and operating it for 15 minutes ensures that all trains are OPERABLE and that all associated controls are functioning properly. It also ensures that motor failure can be
detected for corrective action. The 31 day Frequency was
developed considering the known reliability of fan motors
and controls, the two train redundancy available, and the
iodine removal capability of the Containment Spray System
independent of the IRS.
SR 3.6.8.2 This SR verifies that the required IRS filter testing is performed in accordance with the Ventilation Filter Testing
Program. The IRS filter tests are in accordance withportions ofReference
- 2. The Ventilation Filter Testing IRS B 3.6.8 BASESCALVERT CLIFFS - UNITS 1 & 2B 3.6.8-4Revision 2 Program includes testing high efficiency particulate air filter performance, charcoal adsorber efficiency, minimum system flow rate, and the physical properties of the
activated charcoal (general use and following specific
operations). Specific test frequencies and additional
information are discussed in detail in the Ventilation Filter Testing Program
.SR 3.6.8.3 The automatic startup test verifies that both trains of
equipment start upon receipt of an actual or simulated test
signal (Engineered Safety Feature Actuation System
). The 24 month Frequency is based on the need to perform this
s urveillance test under the conditions that apply during a plant outage and the potential for an unplanned transient if
the s urveillance test were performed with the reactor at power. Operating experience has shown that these components
usually pass the s urveillance test when performed at the 24 month Frequency. Therefore, the Frequency was concluded
to be acceptable from a reliability standpoint.
Furthermore, the Frequency was developed considering that
the system equipment OPERABILITY is demonstrated on a 31 day
Frequency by SR 3.6.8.1.REFERENCES1.UFSAR 2.Regulatory Guide 1.52, Revision 2, "Design, Testing, and Maintenance Criteria for Postaccident Engineered-Safety-Feature Atmosphere Cleanup System Air Filtration and Adsorption Units of Light-Water-Cooled Nuclear Power Plants
," March 1978