Notice of Opportunity To Comment on Model Safety Evaluation on Technical Specification Improvement for B&W Reactor Plants To Risk-Inform Requirements Regarding Selected Required Action End-States Using the Consolidated Line Item Improvement Process, 65615-65629 [E7-22738]

Agencies

• NUCLEAR REGULATORY COMMISSION

[Federal Register Volume 72, Number 224 (Wednesday, November 21, 2007)]
[Notices]
[Pages 65615-65629]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-22738]


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NUCLEAR REGULATORY COMMISSION


Notice of Opportunity To Comment on Model Safety Evaluation on 
Technical Specification Improvement for B&W Reactor Plants To Risk-
Inform Requirements Regarding Selected Required Action End-States Using 
the Consolidated Line Item Improvement Process

AGENCY: Nuclear Regulatory Commission.

ACTION: Request for comment.

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SUMMARY: Notice is hereby given that the staff of the Nuclear 
Regulatory Commission (NRC) has prepared a model safety evaluation (SE) 
and model license amendment request (LAR) relating to changes to the 
end-state requirements for required actions in B&W reactor plants' 
technical specifications (TS). Current technical specification action 
requirements frequently require that the unit be brought to cold 
shutdown when the technical specification limiting condition for 
operation for a system has not been met. Depending on the system, and 
the affected safety function, the requirement to go to cold shutdown 
may not represent the most risk effective course of action. In 
accordance with a qualitative risk analysis that provides a basis for 
changes to the action requirement to shutdown, where appropriate the 
shutdown end-state is changed from cold shutdown to hot shutdown. The 
affected TS are:

3.3.5 Engineered Safety Feature Actuation System (ESFAS) 
Instrumentation.
3.3.6 ESFAS Manual Initiation.
3.4.6 Reactor Coolant System (RCS) Loops--MODE 4.
3.4.15 RCS Leakage Detection Instrumentation.
3.5.4 Borated Water Storage Tank (BWST).
3.6.2 Containment Air Locks.
3.6.3 Containment Isolation Valves.
3.6.4 Containment Pressure.
3.6.5 Containment Air Temperature.
3.6.6 Containment Spray and Cooling Systems.
3.7.7 Component Cooling Water System.
3.7.8 Service Water System.
3.7.9 Ultimate Heat Sink.
3.7.10 Control Room Emergency Ventilation System (CREVS).
3.7.11 Control Room Emergency Air Temperature Control System 
(CREATCS).
3.8.1 AC Sources--Operating.
3.8.4 DC Sources--Operating.
3.8.7 Inverters--Operating.
3.8.9 Distribution Systems--Operating.

    The NRC staff has also prepared a model no significant hazards 
consideration (NSHC) determination relating to this matter. The purpose 
of these models is to permit the NRC to efficiently process amendments 
that propose to adopt technical specification changes, designated as 
TSTF-431, Revision 2, related to Topical Report BAW-2441, Revision 2, 
``Risk Informed Justification for LCO End-State Changes,'' September 
2006. Licensees of B&W nuclear power reactors to which the models apply 
could then request amendments utilizing the models and justifying the 
applicability of the SE and NSHC determination to their reactors. The 
NRC staff is requesting comments on the model SE, model LAR, and model 
NSHC determination prior to announcing their availability for 
referencing in license amendment applications.

DATES: The comment period expires December 21, 2007. Comments received 
after this date will be considered if it is practical to do so, but the 
Commission is able to ensure consideration only for comments received 
on or before this date.

ADDRESSES: Comments may be submitted either electronically or via U.S. 
mail.
    Submit written comments to Chief, Rules and Directives Branch, 
Division of Administrative Services, Office of Administration, Mail 
Stop: T-6 D59, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001. Hand deliver comments to: 11545 Rockville Pike, Rockville, 
Maryland, between 7:45 a.m. and 4:15 p.m. on Federal workdays. Copies 
of comments received may be examined at the NRC's Public Document Room, 
11555 Rockville Pike (Room O-1F21), Rockville, Maryland. Comments may 
be submitted by electronic mail to CLIIP@nrc.gov.

FOR FURTHER INFORMATION CONTACT: Timothy Kobetz, Mail Stop: O-12H2, 
Technical Specifications Branch, Division of Inspection & Regional 
Support, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory 
Commission, Washington, DC 20555-0001, telephone 301-415-1932.

SUPPLEMENTARY INFORMATION:

Background

    Regulatory Issue Summary 2000-06, ``Consolidated Line Item 
Improvement Process for Adopting Standard Technical Specification 
Changes for Power Reactors,'' was issued on March 20, 2000. The 
consolidated line item improvement process (CLIIP) is intended to 
improve the efficiency of NRC licensing processes, by processing 
proposed changes to the standard technical specifications (STS) in a 
manner that supports subsequent license amendment applications. The

[[Page 65616]]

CLIIP includes an opportunity for the public to comment on proposed 
changes to the STS after a preliminary assessment by the NRC staff and 
finding that the change will likely be offered for adoption by 
licensees. The CLIIP directs the NRC staff to evaluate any comments 
received for a proposed change to the STS and to either reconsider the 
change or announce the availability of the change for adoption by 
licensees. Licensees opting to apply for this TS change are responsible 
for reviewing the staff's evaluation, referencing the applicable 
technical justifications, and providing any necessary plant-specific 
information. Each amendment application made in response to the notice 
of availability will be processed and noticed in accordance with 
applicable NRC rules and procedures.
    This notice solicits comment on changes to the end-state 
requirements for required actions, if risk is assessed and managed, for 
the primary purpose of accomplishing short-duration repairs which 
necessitated exiting the original Mode of operation. The change was 
proposed in Topical Report BAW-2441, Revision 2, ``Risk Informed 
Justification for LCO End-State Changes,'' September 2006. This change 
was proposed for incorporation into the standard technical 
specifications by the owners groups participants in the Technical 
Specification Task Force (TSTF) and is designated TSTF-431, Revision 2. 
TSTF-431, Revision 2, can be viewed on the NRC's web page at https://
www.nrc.gov/reactors/operating/licensing/techspecs.html.

Applicability

    This proposal to modify technical specification requirements by the 
adoption of TSTF-431, Revision 2, is applicable to all licensees of B&W 
plants. To efficiently process the incoming license amendment 
applications, the staff requests that each licensee applying for the 
changes proposed in TSTF-431, Revision 2, include Bases for the 
proposed TS consistent with the Bases proposed in TSTF-431, Revision 2. 
To efficiently process the incoming license amendment applications, the 
staff requests that each licensee applying for the changes proposed in 
TSTF-431, Revision 2, use the CLIIP. Licensees are not prevented from 
requesting an alternative approach or proposing the changes without the 
requested Bases and Bases control program. Variations from the approach 
recommended in this notice may require additional review by the NRC 
staff, and may increase the time and resources needed for the review. 
Significant variations from the approach, or inclusion of additional 
changes to the license, will result in staff rejection of the 
submittal. Instead, licensees desiring significant variations and/or 
additional changes should submit a LAR that does not claim to adopt 
TSTF-431, Revision 2.

Public Notices

    This notice requests comments from interested members of the public 
within 30 days of the date of publication in the Federal Register. 
After evaluating the comments received as a result of this notice, the 
staff will either reconsider the proposed change or announce the 
availability of the change in a subsequent notice (perhaps with some 
changes to the SE, LAR, or the proposed NSHC determination as a result 
of public comments). If the staff announces the availability of the 
change, licensees wishing to adopt the change must submit an 
application in accordance with applicable rules and other regulatory 
requirements. For each application, the staff will publish a notice of 
consideration of issuance of amendment to facility operating licenses, 
a proposed NSHC determination, and a notice of opportunity for a 
hearing. The staff will also publish a notice of issuance of an 
amendment to operating license to announce the modification of end-
state requirements for required actions in plant technical 
specifications.

Proposed Model Plant Specific Safety Evaluation for Technical 
Specification Task Force (TSTF) Change TSTF-431, Revision 2, Change in 
Technical Specifications End-States (BAW-2441), a Consolidated Line 
Item Improvement

U.S. NUCLEAR REGULATORY COMMISSION SAFETY EVALUATION BY THE OFFICE OF 
NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. [------] TO 
FACILITY OPERATING LICENSE NFP-[------] [UTILITY NAME] [PLANT NAME], 
[UNIT ------] DOCKET NO. -[------]
1.0 Introduction
    By letter dated ------------, 20----, [Utility Name] (the licensee) 
proposed changes to the technical specifications (TS) for [plant name]. 
The requested changes are the adoption of TSTF-431, Revision 2, to the 
B&W Reactor Standard Technical Specifications (STS) (NUREG-1430), which 
was proposed by the Technical Specifications Task Force (TSTF) on July 
13, 2007, on behalf of the industry. TSTF-431, Revision 2, incorporates 
the B&W Owners Group (B&WOG) approved Topical Report BAW-2441, Revision 
2, ``Risk Informed Justification for LCO End-State Changes,'' September 
2006, (Reference 1), into the B&W STS (Note: The changes are made with 
respect to Revision 3 of the STS NUREGs).
    TSTF-431, Revision 2, is one of the industry's initiatives 
developed under the Risk Management Technical Specifications (RMTS) 
program. These initiatives are intended to maintain or improve safety 
through the incorporation of risk assessment and management techniques 
in TS, while reducing unnecessary burden and making TS requirements 
consistent with the Commission's other risk-informed regulatory 
requirements, in particular the maintenance rule.
    The Code of Federal Regulations, 10 CFR 50.36, ``Technical 
Specifications,'' states: ``When a limiting condition for operation of 
a nuclear reactor is not met, the licensee shall shut down the reactor 
or follow the remedial action permitted by the technical specification 
until the condition can be met.'' The STS and many plant TS provide a 
completion time (CT) for the plant to meet the limiting condition for 
operation (LCO). If the LCO or the remedial action cannot be met, then 
the reactor is required to be shut down. When the STS and individual 
plant technical specifications were written, the shutdown condition or 
end-state specified was usually cold shutdown.
    Topical Report BAW-2441, Revision 2, provides the technical basis 
to change certain required end-states when the TS Actions for remaining 
in power operation cannot be met within the CTs. Most of the requested 
TS changes permit an end-state of hot shutdown (Mode 4), if risk is 
assessed and managed, rather than an end-state of cold shutdown (Mode 
5) contained in the current TS. The request was limited to those end-
states where: (1) Entry into the shutdown mode is for a short interval, 
(2) entry is initiated by inoperability of a single train of equipment 
or a restriction on a plant operational parameter, unless otherwise 
stated in the applicable TS, and (3) the primary purpose is to correct 
the initiating condition and return to power operation as soon as is 
practical.
    The STS for B&W plants defines six operational modes. In general, 
they are:
     Mode 1--Power Operation: Keff >= 0.99 and power 
>5% RTP.
     Mode 2--Startup: Keff >= 0.99 and power <= 5% 
RTP.
     Mode 3--Hot Standby: Keff < 0.99 and Tav 
>= [330][deg]F.
     Mode 4--Hot Shutdown: Keff < 0.99 and 
[330][deg]F >= Tav >= [200][deg]F.
     Mode 5--Cold Shutdown: Keff < 0.99 and Tav 
<= [200][deg]F.

[[Page 65617]]

     Mode 6--Refueling: One or more reactor vessel head closure 
bolts are less than fully tensioned.
    TSTF-431, Revision 2, generally allows a Mode 4 end-state rather 
than a Mode 5end-state for selected initiating conditions in order to 
perform short-duration repairs which necessitate exiting the original 
Mode of operation. The affected TS are:

3.3.5 Engineered Safety Feature Actuation System (ESFAS) 
Instrumentation.
3.3.6 ESFAS Manual Initiation.
3.4.6 Reactor Coolant System (RCS) Loops--MODE 4.
3.4.15 RCS Leakage Detection Instrumentation.
3.5.4 Borated Water Storage Tank (BWST).
3.6.2 Containment Air Locks.
3.6.3 Containment Isolation Valves.
3.6.4 Containment Pressure.
3.6.5 Containment Air Temperature.
3.6.6 Containment Spray and Cooling Systems.
3.7.7 Component Cooling Water System.
3.7.8 Service Water System.
3.7.9 Ultimate Heat Sink.
3.7.10 Control Room Emergency Ventilation System (CREVS).
3.7.11 Control Room Emergency Air Temperature Control System 
(CREATCS).
3.8.1 AC Sources--Operating.
3.8.4 DC Sources--Operating.
3.8.7 Inverters--Operating.
3.8.9 Distribution Systems--Operating.
2.0 Regulatory Evaluation
    In 10 CFR 50.36, the Commission established its regulatory 
requirements related to the content of TS. Pursuant to 10 CFR 50.36(c), 
TS are required to include items in the following five specific 
categories related to plant operation: (1) Safety limits, limiting 
safety system settings, and limiting control settings; (2) limiting 
conditions for operation (LCOs); (3) surveillance requirements (SRs); 
(4) design features; and (5) administrative controls. The rule does not 
specify the particular requirements to be included in a plant's TS.
    As stated in 10 CFR 50.36(c)(2)(i), the ``Limiting conditions for 
operation are the lowest functional capability or performance levels of 
equipment required for safe operation of the facility. When a limiting 
condition for operation of a nuclear reactor is not met, the licensee 
shall shut down the reactor or follow any remedial action permitted by 
the technical specifications * * * .''
    BAW-2441-A, Revision 2, ``Risk-Informed Justification for LCO End-
State Changes,'' September 2006 (Reference 1), provides justification 
for changes to the end-states of selected LCO from Mode 5, cold 
shutdown, to Mode 4, hot shutdown, in order to (1) reduce risk 
associated with unnecessary shutdown cooling (SDC) operations, and (2) 
reduce plant unavailability associated with reduced plant downtime 
caused by unnecessary cooldown to Mode 5 and subsequent reheat to Mode 
3 or 4. Reference 1 provides both a qualitative assessment and a 
quantitative analysis to confirm that Mode 4 is the preferred end-state 
from a risk and operational perspective. The qualitative assessment 
describes the risk associated with operation in Mode 4 compared to 
operation in Mode 5, in order to justify that the end-state of Mode 4, 
versus Mode 5, for the proposed LCO conditions invoked, is acceptable. 
The qualitative assessment concludes that the risk advantages 
associated with Mode 4 operation versus Mode 5 operation are that: More 
initiating event mitigating resources are available; human error during 
SDC initiation and subsequent operation cannot occur; SDC 
vulnerabilities are avoided; and inadvertent RCS draining via SDC 
system related misalignments cannot occur.
    Most of today's TS and the design basis analyses were developed 
based on the perception that putting a plant in cold shutdown would 
result in the safest condition and that the design basis analyses would 
bound credible shutdown accidents. In the late 1980s and early 1990s, 
the NRC and licensees recognized that this perception was incorrect and 
took corrective actions to improve shutdown operation. At the same 
time, standard TS were developed and many licensees improved their TS. 
Since enactment of a shutdown rule was expected, almost all TS changes 
involving power operation, including a revised end-state requirement, 
were postponed (see, e.g., the Final Policy Statement on TS 
Improvements (Reference 2)). However, in the mid 1990s, the Commission 
decided a shutdown rule was not necessary in light of industry 
improvements.
    Controlling shutdown risk encompasses control of conditions that 
can cause potential initiating events and responses to those initiating 
events that may occur. Initiating events are a function of equipment 
malfunctions and human error. Responses to events are a function of 
plant sensitivity, ongoing activities, human error, defense-in-depth, 
and additional equipment malfunctions.
    In practice, the risk during shutdown operations is often addressed 
via voluntary actions and application of 10 CFR 50.65 (Reference 3), 
the maintenance rule. Section 50.65(a)(4) states: ``Before performing 
maintenance activities * * * the licensee shall assess and manage the 
increase in risk that may result from the proposed maintenance 
activities. The scope of the assessment may be limited to structures, 
systems, and components that a risk-informed evaluation process has 
shown to be significant to public health and safety.'' Regulatory Guide 
(RG) 1.182 (Reference 4) provides guidance on implementing the 
provisions of 10 CFR 50.65(a)(4) by endorsing the revised Section 11 
(published separately) to NUMARC 93-01, Revision 2. That section was 
subsequently incorporated into Revision 3 of NUMARC 93-01 (Reference 
5). However, Revision 3 has not yet been formally endorsed by the NRC.
    The changes in TSTF-431 are consistent with the rules, regulations 
and associated regulatory guidance, as noted above.

3.0 Technical Evaluation

    The changes proposed in TSTF-431, Revision 2, are consistent with 
the changes proposed and justified in Topical Report BAW-2441, Revision 
2, as approved by the associated NRC SE (Reference 6). The evaluation 
included in Reference 6, as appropriate and applicable to the changes 
of TSTF-431, Revision 2 (Reference 7), is reiterated herein.
    In its application, the licensee shall commit to TSTF-IG-07-01, 
Implementation Guidance for TSTF-431, Revision 1, ``Change in Technical 
Specifications End-States (BAW-2441),'' (Reference 8), which addresses 
a variety of issues. An overview of the generic evaluation and 
associated risk assessment is provided below, along with a summary of 
the associated TS changes justified by Reference 1.
3.1 Risk Assessment
    The objective of the BAW-2441, Revision 2, (Reference 1) risk 
assessment was to show that any risk increases associated with the 
proposed changes in TS end-states are either negligible or negative 
(i.e., a net decrease in risk).
    BAW-2441, Revision 2, documents a risk-informed analysis of the 
proposed TS change. Probabilistic Risk Assessment (PRA) results and 
insights were used, in combination with results of deterministic 
assessments, to identify and propose changes in ``end-states'' for B&W 
plants. This is in accordance with guidance provided in RG 1.174 
(Reference 9) and RG 1.177 (Reference 10). The three-tiered approach 
documented in RG 1.177, ``An Approach for Plant-Specific, Risk-Informed 
Decision Making: Technical Specifications,'' was followed. The first 
tier of the three-tiered approach

[[Page 65618]]

includes the assessment of the risk impact of the proposed change for 
comparison to acceptance guidelines consistent with the Commission's 
Safety Goal Policy Statement, as documented in RG 1.174 ``An Approach 
for Using Probabilistic Risk Assessment in Risk-Informed Decisions on 
Plant-Specific Changes to the Licensing Basis.'' In addition, the first 
tier aims at ensuring that there are no unacceptable temporary risk 
increases during the implementation of the proposed TS change, such as 
when equipment is taken out of service. The second tier addresses the 
need to preclude potentially high-risk configurations which could 
result if equipment is taken out of service concurrently with the 
implementation of the proposed TS change. The third tier addresses the 
application of a configuration risk management program (CRMP), 
implemented to comply with 10 CFR 50.65(a)(4) of the Maintenance Rule, 
for identifying risk-significant configurations resulting from 
maintenance-related activities and taking appropriate compensatory 
measures to avoid such configurations. Unless invoked, such as by this 
or another TS application, 50.65(a)(4) is applicable to maintenance-
related activities and does not cover other operational activities 
beyond the effect they may have on existing maintenance related risk.
    The risk assessment approach of BAW-2441, Revision 2, was found 
acceptable in the SE for the topical report. In addition, the analyses 
show that the the three-tiered approach criteria for allowing TS 
changes are met as follows:
     Risk Impact of the Proposed Change (Tier 1). The risk 
changes associated with the TS changes in TSTF-431, in terms of mean 
yearly increases in core damage frequency (CDF) and large early release 
frequency (LERF), are risk neutral or risk beneficial. In addition, 
there are no significant temporary risk increases, as defined by RG 
1.177 criteria, associated with the implementation of the TS end-state 
changes.
     Avoidance of Risk-Significant Configurations (Tier 2). The 
performed risk analyses, which are based on single LCOs, show that 
there are no high-risk configurations associated with the TS end-state 
changes. The reliability of redundant trains is normally covered by a 
single LCO. To provide assurance that risk-significant plant equipment 
outage configurations will not occur when specific equipment is out of 
service, as part of the implementation of TSTF-431, the licensee will 
commit to follow Section 11 of NUMARC 93-01, Revision 3, and to include 
guidance in appropriate plant procedures and/or administrative controls 
to preclude high-risk plant configurations when the plant is at the 
proposed end-state. The staff finds that such guidance is adequate for 
preventing risk-significant plant configurations.
     Configuration Risk Management (Tier 3). The licensee shall 
have a program, the CRMP, in place to comply with 10 CFR 50.65(a)(4) to 
assess and manage the risk from proposed maintenance activities. This 
program can be used to support a licensee decision in selecting the 
appropriate actions to control risk for most cases in which a risk-
informed TS is entered. When multiple LCOs occur, which affect trains 
in several systems, the plant's risk-informed CRMP, implemented in 
response to the Maintenance Rule 10 CFR 50.65(a)(4), shall ensure that 
high-risk configurations are avoided. In addition, to the extent that 
the plant PRA is utilized in the CRMP, the plant PRA quality will be 
assessed in accordance with NRC Regulatory Issue Summary 2007-06, 
``Regulatory Guide 1.200 Implementation,'' (Reference 11).
    The generic risk impact of the proposed end-state mode change was 
evaluated subject to the following assumptions:
    1. The entry into the proposed end-state is initiated by the 
inoperability of a single train of equipment or a restriction on a 
plant operational parameter, unless otherwise stated in the applicable 
technical specification.
    2. The primary purpose of entering the end-state is to correct the 
initiating condition and return to power as soon as practical.
    3. Plant implementation guidance for the proposed end-state changes 
is developed to ensure that insights and assumptions made in the risk 
assessment are properly reflected in the plant-specific CRMP.
    These assumptions are consistent with typical entries into Mode 4 
for short duration repairs, which is the intended use of the TS end-
state changes.
    The staff concludes that, in general, going to Mode 4 (hot 
shutdown) instead of going to Mode 5 (cold shutdown) to carry out 
equipment repairs does not have any adverse effect on plant risk.
3.2 Assessment of TS Changes
    The changes proposed by the licensee and in TSTF-431, Revision 2, 
are consistent with the changes proposed in topical report BAW-2441, 
Revision 2, and approved by the NRC SE of August 25, 2006. [NOTE: Only 
those changes proposed in TSTF-431, Revision 2, are addressed in this 
SE. The SE and associated topical report address the entire fleet of 
B&W plants, and the plants adopting TSTF-431, Revision 2, must confirm 
the applicability of the changes to their plant.] Following are the 
proposed changes, including a synopsis of the STS LCO, the change, and 
a brief conclusion of acceptability.
3.2.1 TS 3.3.5 Engineering Safety Features Actuation System (ESFAS) 
Instruments
    ESFAS instruments initiate high pressure injection (HPI), low 
pressure injection (LPI), containment spray and cooling, containment 
isolation, and onsite standby power source start. ESFAS also provides a 
signal to the Emergency Feedwater Isolation and Control (EFIC) System. 
This signal initiates emergency feed water (EFW) when HPI is initiated. 
All functions associated with these systems, structures and components 
(SSCs) can be initiated via operator action. This may be accomplished 
at the channel level or the individual component level.
    LCO: Three channels of ESFAS instrumentation for the applicable 
parameters shall be operable in each ESFAS train.
    Condition Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.3.5 Condition B, Required Action B.2.3 
and addresses only the reactor building (RB) High Pressure and RB High-
High Pressure setpoints. Specifically, if two or more channels are 
inoperable or one channel is inoperable and the required action is not 
met, then the Mode 5 end-state is prescribed within 36 hours subsequent 
to an initial cooldown to Mode 3 within 6 hours.
    Proposed Modification for End-State Required Actions: The end-state 
associated with Required Action B.2.3 of this LCO is being proposed to 
be changed from Mode 5 within 36 hours to Mode 4 within 12 hours.
    Assessment and Finding: When operating in Mode 4, the reactor 
system thermal-hydraulic conditions are very different from those 
associated with a design basis accident (DBA) (at-power). That is, the 
energy in the RCS is only that associated with decay heat in the core 
and the stored energy in the reactor coolant system (RCS) components 
and RCS pressure is reduced (especially toward the lower end of Mode 
4). This means that the likelihood of an initiating event (IE) 
occurring, for which ESFAS would provide mitigating functions, is 
greatly reduced when operating in Mode 4. Nonetheless, all

[[Page 65619]]

redundant functions initiated by ESFAS can be manually initiated to 
mitigate transients that will proceed more slowly and with reduced 
challenge to the reactor and containment systems than those associated 
with at-power operations. Also, when operating toward the lower end of 
Mode 4, with the steam generators (SGs) in operation and SDC not in 
operation, risk is reduced; risk associated with shutdown cooling (SDC) 
operation is avoided. When operating in Mode 4 there are more 
mitigation systems (e.g., HPI and EFW/auxiliary feed water (AFW)) 
available to respond to IEs that could challenge RCS inventory or decay 
heat removal, than when operating in Mode 5. These systems include the 
HPI system and EFW/AFW systems. Based on the above analysis, the staff 
finds that the above requested change is acceptable.
3.2.2 TS 3.3.6 ESFAS Manual Initiation
    The ESFAS manual initiation capability allows the operator to 
actuate ESFAS functions from the main control room in the absence of 
any other initiation condition. Manually actuated functions include 
HPI, LPI, containment spray and cooling, containment isolation, and 
control room isolation. The ESFAS manual initiation ensures that the 
control room operator can rapidly initiate Engineered Safety Features 
(ESF) functions at any time. In the absence of manual ESFAS initiation 
capability, the operator can initiate any and all ESF functions 
individually at a lower level.
    LCO: Two manual initiation channels of each one of the following 
ESFAS functions shall be operable: HPI, LPI, RB Cooling, RB Spray, RB 
Isolation, and Control Room Isolation.
    Conditions Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.3.6 Condition B, Required Action B.2. 
Specifically, if one or more ESFAS functions with one channel are 
inoperable and the required action and associated completion time are 
not met, then Mode 3 is prescribed within 6 hours and Mode 5 within 36 
hours.
    Proposed Modification for End-State Required Actions: The end-state 
associated with Required Action B.2 of this LCO is being proposed to be 
changed from Mode 5 within 36 hours to Mode 4 within 12 hours.
    Assessment and Finding: When operating in Mode 4, the thermal-
hydraulic conditions are very different than those associated with a 
DBA (at-power). That is, the energy in the RCS is only that associated 
with decay heat in the core and the stored energy in the RCS components 
and RCS pressure is reduced (especially toward the lower end of Mode 
4). This means that the likelihood of an IE occurring, for which ESFAS 
manual initiation would provide mitigating functions, is greatly 
reduced when operating in Mode 4. Nonetheless, all redundant functions 
initiated by ESFAS manual initiation can be manually initiated via 
individual component controls. In this way, transients, that will 
proceed more slowly and with reduced challenge to the reactor and 
containment systems than those associated with at-power operations, 
will be mitigated. Also, when operating toward the lower end of Mode 4, 
with the SGs in operation and SDC not in operation, risk is reduced 
(i.e., the risk associated with SDC avoided). When operating in Mode 4 
there are more mitigation systems (e.g. HPI and EFW/AFW) available to 
respond to IEs that could challenge RCS inventory or decay heat 
removal, than when operating in Mode 5. These systems include the HPI 
system and EFW/AFW systems. Based on the above assessment, the staff 
finds that the above requested change is acceptable.
3.2.3 TS 3.4.6 RCS Loops--MODE 4
    The purpose of this LCO is to provide forced flow from at least one 
RCP or one decay heat removal (DHR) pump for core decay heat removal 
and transport. This LCO allows the two loops that are required to be 
operable to consist of any combination of RCS or DHR system loops. Any 
one loop in operation provides enough flow to remove the decay heat 
from the core. The second loop that is required to be operable provides 
redundant paths for heat removal. An ancillary function of the RCS and/
or DHR loops is to provide mixing of boron in the RCS. When operating 
in Mode 4 if both RCS loops and one DHR loop is inoperable, the 
existing LCO requires cooldown to Mode 5. In this situation, SGs are 
available for core heat removal and transport via natural circulation 
(NC) in Mode 4 without a need for significant RCS heatup. Proceeding to 
Mode 5 makes few if any additional systems available for decay heat 
removal (assuming a failure of the remaining DHR/LPI system). The one 
system that can be made available in Mode 5 to provide backup to the 
DHR system is the Borated Water Storage Tank (BWST). It can provide 
gravity draining to the RCS after cooldown to Mode 5 and subsequent RCS 
drain down and removal of SG primary side manway covers. This would 
require a considerable time delay, during which RC temperature would be 
increasing.
    LCO: Two loops consisting of any combination of RCS loops and DHR 
loops shall be operable and one loop shall be in operation.
    Condition Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.4.6 Condition A, Required Action A.2. 
Specifically, if one required loop is inoperable, then action is taken 
immediately to restore a second loop to operable status. Further, if 
the remaining operable loop is a DHR loop, then entry into Mode 5 is 
required within 24 hours.
    Proposed Modification for End-State Required Actions: It is 
proposed that Required Action A.2 be deleted, thus allowing continued 
operations in Mode 4.
    Assessment and Finding: When operating in Mode 4, if both RCS loops 
and one DHR loop are inoperable, the existing LCO requires cooldown to 
Mode 5. In this situation, SGs are available for core heat removal and 
transport via NC in Mode 4 without the need for significant RCS heatup. 
Proceeding to Mode 5 makes few if any additional systems available for 
decay heat removal (assuming a failure of the remaining DHR system). 
The one system that can be made available in Mode 5 to provide backup 
to the DHR system is the BWST. It can provide gravity draining to the 
RCS after cooldown to Mode 5 and subsequent RCS drain down and removal 
of SG primary side manway covers. This would require a considerable 
time delay, during which RC temperature would be increasing. Given 
these considerations and magnitude of feedwater systems available to 
feed the SGs, continued use of SGs for this situation will adequately 
cool the core while avoiding the additional risk associated with SDC. 
RC boron concentration will have been adjusted prior to cooldown to 
Mode 4 to provide 1% shutdown margin (SDM) at the target cooldown 
temperature. Thus, boron concentration adjustments would not be 
necessary; RC boron would be sufficiently mixed to an equilibrium 
concentration by this time. When operating in Mode 4 there are more 
mitigation systems available to respond to IEs that could challenge RCS 
inventory or decay heat removal, than when operating in Mode 5. These 
systems include the HPI system and EFW/AFW systems. Based upon the 
above assessment, the staff finds that the above requested change is 
acceptable.
3.2.4 TS 3.4.15 RCS Leakage Detection Instrumentation
    One method of protecting against large RCS leakage derives from the 
ability of instruments to rapidly detect

[[Page 65620]]

extremely small leaks. This LCO requires instruments of diverse 
monitoring principles to be operable to provide a high degree of 
confidence that extremely small leaks are detected in time to allow 
actions to place the plant in a safe condition when RCS leakage 
indicates possible RC pressure boundary (RCPB) degradation. The LCO 
requirements are satisfied when monitors of diverse measurement means 
are available.
    LCO: The following RCS leakage detection instrumentation shall be 
operable:
    a. One containment sump monitor and
    b. One containment atmosphere radioactivity monitor (gaseous or 
particulate).
    Conditions Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.4.15 Condition C, Required Action C.2. 
Specifically, if either the sump monitor or containment atmosphere 
radioactivity monitor are inoperable and cannot be restored to 
operability within 30 days, then Mode 3 is prescribed within 6 hours 
and Mode 5 within 36 hours.
    Proposed Modification for End-State Required Actions: The end-state 
associated with Required Action C.2 of this LCO is being proposed to be 
changed from Mode 5 within 36 hours to Mode 4 within 12 hours.
    Assessment and Finding: Due to reduced RCS pressures when operating 
in Mode 4, especially toward the lower end of Mode 4, the likelihood of 
occurrence of a LOCA is very small; LOCA IE frequencies are reduced 
compared to at-power operation. Because of this and because the reactor 
is shutdown with significant radionuclide decay having occurred, the 
probability of occurrence of a LOCA is decreased while the consequence 
of such an event is not increased. Additional instruments are available 
to provide secondary indication of a LOCA, e.g., additional containment 
radioactivity monitors, grab samples of containment atmosphere, 
humidity, temperature and pressure. Plant risk is lower when operating 
in Mode 4 (not on SDC) than when operating in Mode 5; risk associated 
with SDC operation is avoided. When operating in Mode 4 (not on SDC) 
there are more mitigation systems (e.g., HPI and EFW/AFW) available to 
respond to lEs that could challenge RCS inventory or decay heat 
removal, than when operating in Mode 5. Based upon the above 
assessment, the staff finds that the above requested change is 
acceptable.
3.2.5 TS 3.5.4 Borated Water Storage Tank (BWST)
    The BWST supports the emergency core cooling system (ECCS) and the 
RB spray (RBS) system by providing a source of borated water for ECCS 
and containment spray pump operation. The BWST supplies two ECCS 
trains, each by a separate, redundant supply header. Each header also 
supplies one train of RBS . A normally open, motor operated isolation 
valve is provided in each header to allow the operator to isolate the 
BWST from the ECCS after the ECCS pump suction has been transferred to 
the containment sump following depletion of the BWST during a LOCA. The 
ECCS and RBS are provided with recirculation lines that ensure each 
pump can maintain minimum flow requirements when operating at shutoff 
head conditions. This LCO ensures that: the BWST contains sufficient 
borated water to support the ECCS during the injection phase, 
sufficient water volume exists in the containment sump to support 
continued operation of the ECCS and containment spray pumps at the time 
of transfer to the recirculation mode of cooling, and the reactor 
remains subcritical following a LOCA. Insufficient water inventory in 
the BWST could result in insufficient cooling capacity of the ECCS when 
the transfer to the recirculation mode occurs. Improper boron 
concentrations could result in a reduction of SDM or excessive boric 
acid precipitation in the core following a LOCA, as well as excessive 
caustic stress corrosion of mechanical components and systems inside 
containment.
    LCO: The BWST shall be operable.
    Condition Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.5.4 Condition C, Required Action C.2. 
Specifically, if boron concentration is not within limits for 8 hours, 
then Mode 3 is prescribed within 6 hours and Mode 5 within 36 hours.
    Proposed Modification: The end-state associated with Required 
Action C.2, as it relates to the boron concentration requirement of 
this LCO, is being proposed to be changed from Mode 5 within 36 hours 
to Mode 4 within 12 hours. No change is being proposed for the water 
temperature requirement of the LCO. The end-state associated with 
existing C.2 is proposed to be changed as follows:
    4. Split existing Condition A into two conditions (A and C) such 
that boron concentration and water temperature are addressed 
separately, i.e., Condition A would address boron concentration and 
Condition C would address water temperature. In either case the 
Required Action, i.e., A.1 and C.1, would be to restore the BWST to 
operable status within 8 hours.
    5. A new Condition B would address boron concentration not within 
limits and the Required Action and associated Completion Time not met. 
Required Action B.1 would be to be in Mode 3 within 6 hours and B.2 
would be to be in Mode 4 within 12 hours.
    6. Existing Condition B would be renamed Condition D and would 
address BWST inoperable for reasons other than Conditions A or C with a 
Required Action D.1 to restore the BWST to operable status within I 
hour.

Existing Condition C would be renamed Condition E and would address 
Required Action and associated Completion Time for Conditions other 
than Condition C or D not met. It would have the Required Action to be 
in Mode 3 within 6 hours and Mode 5 within 36 hours.
    Assessment and Finding: The limit for minimum boron concentration 
in the BWST was established to ensure that, following a DBA large break 
loss of coolant accident (LBLOCA), with a minimum BWST level, the 
reactor will remain shut down in the cold condition following mixing of 
the BWST and RCS water volumes. LBLOCA accident analyses assume that 
all control rods remain withdrawn from the core. When operating in Mode 
4, the control rods will either be inserted or the regulating rod 
groups will be inserted with one or more of the safety rod groups 
cocked and armed for automatic RPS insertion. Hence, all rods will not 
be out should an IE occur. Also, given the highly unlikely possibility 
of a LBLOCA occurring, it can be assumed all control rods will be 
inserted should an IE occur while in Mode 4. This provides for the 
reactor shutdown margin to be very conservative, i.e., in excess of 
approximately -9.0% [Delta]k/k. For these reasons, and the design basis 
assumptions that (a) deviations in boron concentration will be 
relatively slow and small and that (b) boric acid addition systems 
would normally be available (can be powered by [onsite standby power 
sources]), the staff finds that the above requested change is 
acceptable.
3.2.6 TS 3.6.2 Containment Air Locks
    Containment air locks form part of the containment pressure 
boundary and provide a means for personnel access during all modes of 
operation. As such, air lock integrity and leak tightness is essential 
for maintaining the containment leakage rate within limits in the event 
of a DBA. Each air lock is

[[Page 65621]]

fitted with redundant seals and doors as a design feature for 
mitigating the DBA. When operating in Mode 4 the energy that can be 
released to the RB is a fraction of that which would be released for a 
DBA. Also, the redundant containment spray and cooling systems, 
required to be operable in Mode 4 but not in Mode 5, will be available 
to ensure that containment pressure remains low should a LOCA occur.
    LCO: Two containment air locks shall be operable.
    Condition Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.6.2 Condition D, Required Action D.2. 
Specifically, if one or more containment air locks are inoperable for 
reasons other than condition A or B, then restore the air lock to 
operable within 24 hours or Mode 3 is prescribed within 6 hours and 
Mode 5 within 36 hours.
    Proposed Modification for End-State Required Actions: The end-state 
associated with Required Action D.2 of this LCO is being proposed to be 
changed from Mode 5 within 36 hours to Mode 4 within 12 hours.
    Assessment and Finding: The energy that can be released to the RB 
when operating in Mode 4 is only a fraction of that associated with a 
DBA, thus RB pressure will be only slightly higher should a LOCA occur 
when operating in Mode 4 as compared to operating in Mode 5. Required 
Action C.2 requires at least one air lock door to be closed, which 
combined with reduced RB pressure should result in small containment 
air lock leakage. Also, significant radionuclide decay will have 
occurred, i.e., due to plant shutdown. For these reasons, no increase 
in large early release frequency (LERF) is expected. In the unlikely 
event that at least one door cannot be closed, evaluation of the effect 
on plant risk and implementation of any required compensatory measures 
will be accomplished in accordance with 10 CFR 50.65, i.e., the 
``Maintenance Rule.'' Plant risk is lower when operating in Mode 4 (not 
on SDC) than when operating in Mode 5 because there are more mitigation 
systems (e.g., HPI and EFW/AFW) available to respond to IEs that could 
challenge RCS inventory or decay heat removal. Also, the likelihood of 
occurrence of a LOCA is very remote, thus the probability of occurrence 
of a LOCA is decreased while the consequence of such and event is not 
increased, and the staff finds that the above requested change is 
acceptable.
3.2.7 TS 3.6.3 Containment Isolation Valves (CIVs)
    The CIVs form part of the containment pressure boundary and 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. 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 analyses. One of 
these barriers may be a closed system. These barriers (typically CIVs) 
make up the Containment Isolation System. Containment isolation occurs 
upon receipt of a high containment pressure or diverse containment 
isolation signal. The containment isolation signal closes automatic 
containment isolation valves in fluid penetrations not required for 
operation of ESF to prevent leakage of radioactive material. Upon 
actuation of HPI, automatic containment valves also isolate systems not 
required for containment or RCS heat removal. Other penetrations are 
isolated by the use of valves in the closed position or blind flanges. 
As a result, the CIVs (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 a 
DBA. Operability of the containment isolation valves (and blind 
flanges) supports containment operability during accident conditions. 
The operability requirements for containment isolation valves help 
ensure that containment is isolated within the time limits assumed in 
the safety analyses. Therefore, the operability requirements provide 
assurance that the containment function assumed in the safety analyses 
will be maintained. When operating in Mode 4, there is decreased 
potential for challenges to the containment than assumed in the 
licensing basis; thus, containment pressures associated with lEs that 
transfer energy to the containment will be only slightly higher when 
operating in Mode 4 versus operating in Mode 5. When operating in Mode 
4, versus Mode 5, there are more systems available to mitigate 
precursor events, e.g., loss of feedwater and LOCA, that could cause 
potential challenges to containment; also, potential fission product 
release is reduced due to radionuclide decay.
    LCO: Each containment isolation valve shall be operable.
    Condition Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.6.3 Condition E, Required Action E.2. 
Specifically, if the required action and associated completion time 
cannot be met for penetration flow paths with inoperable isolation 
valves or RB purge valve leakage limits (Conditions A, B, C and 
Required Actions A.1, A.2, B.1, C.1 and C.2), then Mode 3 is prescribed 
within 6 hours and Mode 5 within 36 hours.
    Proposed Modification for End-State Required Actions: The end-state 
associated with Required Action E.2 of this LCO is being proposed to be 
changed from Mode 5 within 36 hours to Mode 4 within 12 hours.
    Assessment and Finding: When in Mode 4 (not on SDC) there are more 
mitigation systems available to respond to IEs that could challenge RCS 
inventory or decay heat removal, than when operating in Mode 5. The 
redundant RBS and RB cooling systems will be available to ensure that 
containment pressure remains low should a LOCA occur. Because the 
energy that can be released to the RB when operating in Mode 4 is only 
a fraction of that associated with a DBA, RB pressure will be only 
slightly higher should a LOCA occur when operating in Mode 4 as 
compared to when operating in Mode 5. For these reasons, containment 
leakage associated with CIVs is small, and with the plant shutdown 
significant radionuclide decay will have occurred, therefore no 
increase in LERF is expected. Due to reduced RCS pressures when 
operating in Mode 4, especially toward the lower end of Mode 4, the 
likelihood of occurrence of a LOCA is very small, i.e., LOCA IE 
frequencies are reduced compared to at-power operation. The probability 
of occurrence of a LOCA is decreased while the consequence of such an 
event is not increased. Thus, plant risk is lower when operating in 
Mode 4 (not on SDC) than when operating in Mode 5; risk associated with 
SDC operation is avoided. Therefore, the staff finds that the above 
requested change is acceptable.
3.2.8 TS 3.6.4 Containment Pressure
    The containment pressure is limited during normal operation to 
preserve the initial conditions assumed in the accident analyses for a 
LOCA or steam line break (SLB). The containment air pressure limit also 
prevents the containment pressure from exceeding the containment design 
negative pressure differential with respect to the outside atmosphere 
in the event of inadvertent actuation of the containment spray system. 
Maintaining containment pressure less than or equal to the LCO upper 
pressure limit (in

[[Page 65622]]

conjunction with maintaining the containment temperature limit) ensures 
that: in the event of a DBA, the resultant peak containment accident 
pressure will remain below the containment design pressure; the 
containment environmental qualification operating envelope is 
maintained; and, the ability of containment to perform its design 
function is ensured. The containment high pressure limit is an initial 
condition used in the DBA analyses to establish the maximum peak 
containment internal pressure. Because only a small percentage of the 
energy assumed for the DBA could be released to the containment, this 
limit is overly conservative during operations in Mode 4. The low 
containment pressure limit is based on inadvertent full (both trains) 
actuation of the RB spray system. Invoking any condition associated 
with the LCOs being proposed for an end-state change cannot initiate 
this event; however, should it occur, there is ample time for operator 
response to mitigate it.
    LCO: Containment pressure shall be >=[-2.0] PSIG and <= [+3.0] 
PSIG.
    Condition Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.6.4 Condition B, Required Action B.2. 
Specifically, if containment pressure exceeds the limit and cannot be 
restored within one hour, then Mode 3 is prescribed within 6 hours and 
Mode 5 within 36 hours.
    Proposed Modification for End-State Required Actions: The end-state 
associated with Required Action B.2 of this LCO is being proposed to be 
changed from Mode 5 within 36 hours to Mode 4 within 12 hours.
    Assessment and Finding: The redundant RBS and RB cooling systems 
will be available to ensure that containment pressure remains low 
should a LOCA occur. Because the energy that can be released to the RB 
when operating in Mode 4 is only a fraction of that associated with a 
DBA, RB pressure will be only slightly higher should a LOCA occur when 
operating in Mode 4 as compared to when operating in Mode 5. In such a 
situation, the margin to the RB design pressure will be large, i.e., on 
the order of several tens of PSI. Also, the occurrence of a LOCA of any 
kind during operation in Mode 4 is considered highly unlikely. Because 
of this and the occurrence of significant radionuclide decay (i.e., the 
plant has been shutdown), no increase in LERF is expected should the 
LCO for high containment pressure be invoked while in Mode 4. This is 
especially germane considering that operations personnel will commence 
actions to restore RB pressure to within the limit immediately upon 
notification that it has exceeded the limit. RB vacuum conditions will 
not compromise containment integrity of large dry containment of either 
pre-stressed or reinforced concrete designs. One plant has a steel 
containment configuration fitted with a vacuum breaker to mitigate 
vacuum conditions. The risk associated with Mode 4 operation and RB 
pressure below the LCO low pressure limit coincident with inadvertent 
RB spray actuation is considered to be so low as to be inconsequential 
(a search of available data bases found no record of this situation 
having occurred to date at any B&W design plants). Also, operations 
personnel will commence actions to restore RB pressure to within the 
limit on notification that it has exceeded the limit.
    Plant risk is lower when operating in Mode 4 (not on SDC) than when 
operating in Mode 5; risk associated with SDC operation is avoided. 
Also, when operating in Mode 4 (not on SDC) there are more mitigation 
systems (e.g., HPI and EFW/AFW) available to respond to an IE that 
could challenge RCS inventory or decay heat removal, than when 
operating in Mode 5. These considerations ultimately lead to reduced 
challenges to the RB when operating in Mode 4 versus Mode 5, and 
therefore the staff finds that the above requested change is 
acceptable.
3.2.9 TS 3.6.5 Containment Air Temperature
    The containment average air temperature is limited during normal 
operation to preserve the initial conditions assumed in the accident 
analyses for a LOCA or SLB. The containment average air temperature 
limit is derived from the input conditions used in the containment 
functional analyses and the containment structure external pressure 
analysis. This LCO ensures that initial conditions assumed in the 
analysis of a DBA are not violated during unit operations. The total 
amount of energy to be removed from the RB Cooling system during post 
accident conditions is dependent upon the energy released to the 
containment due to the event as well as the initial containment 
temperature and pressure. The higher the initial temperature, the 
higher the resultant peak containment pressure and temperature. 
Exceeding containment design pressure may result in leakage greater 
than that assumed in the accident analysis. Operation with containment 
temperature in excess of the LCO limit violates an initial condition 
assumed in the accident analysis. The limit for containment average air 
temperature ensures that operation is maintained within the assumptions 
used in the DBA analysis for containment; LOCA results in the greatest 
sustained increase in containment temperature. By maintaining 
containment air temperature at less than the initial temperature 
assumed in the LOCA analysis, the reactor building design condition 
will not be exceeded. As a result, the ability of containment to 
perform its design function is ensured.
    LCO: Containment average air temperature shall be < [130][deg]F.
    Condition Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.6.5 Condition B, Required Action B.2. 
Specifically, if containment air temperature exceeds the limit and 
cannot be restored within 8 hours, then Mode 3 is prescribed within 6 
hours and Mode 5 within 36 hours.
    Proposed Modification for End-State Required Actions: The end-state 
associated with Required Action B.2 of this LCO is being proposed to be 
changed from Mode 5 within 36 hours to Mode 4 within 12 hours.
    Assessment and Finding: The redundant RBS and RB cooling systems 
will be available to ensure that containment temperature remains low 
should a LOCA occur. Because the energy that can be released to the RB 
when operating in Mode 4 is only a fraction of that associated with a 
DBA, the attendant RB temperature (and associated pressure) rise will 
be well below that associated with a DBA. Also, the occurrence of a 
LOCA of any kind during operation in Mode 4 is considered highly 
unlikely. For these reasons and because of the occurrence of 
significant radionuclide decay (i.e., the plant has been shut down), no 
increase in LERF is expected. Plant risk is lower when operating in 
Mode 4 (not on SDC) than when operating in Mode 5; risk associated with 
SDC operation is avoided. Also, when operating in Mode 4 (not on SDC) 
there are more mitigation systems (e.g., HPI and EFV/AFW) available to 
respond to an IE that could challenge RCS inventory or decay heat 
removal, than when operating in Mode 5. These considerations ultimately 
lead to reduced challenges to the RB when operating in Mode 4 versus 
Mode 5. Therefore, the staff finds that the above requested change is 
acceptable.
3.2.10 TS 3.6.6 Containment Spray and Cooling Systems
    The containment spray and cooling systems provide containment 
atmosphere cooling to limit post accident pressure and temperature in 
containment to less than the design values. Reduction of containment

[[Page 65623]]

pressure and the iodine removal capability of the spray reduces the 
release of fission product radioactivity from containment to the 
environment, in the event of a DBA. When operating in Mode 4, the 
release of stored energy to the RB can be only a small fraction of the 
energy associated with a DBA. This, along with the fact there are 
redundant trains of containment spray and cooling, assures this 
engineered safety feature (ESF) will be supported during operation in 
Mode 4. Also, the function associated with containment spray iodine 
removal capability will be less challenged when operating in Mode 4 due 
to radionuclide decay.
    LCO: Two containment spray trains and two containment cooling 
trains shall be operable.
    Condition Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.6.6 Condition B, Required Action B.2 
(containment spray system) and Condition F, Required Action F.2 
(containment cooling system). Specifically: if one containment spray 
train is inoperable and cannot be restored within 72 hours or within 10 
days of discovery of failure to meet the LCO, then Mode 3 is prescribed 
within 6 hours and Mode 5 within 84 hours; and, if two containment 
cooling trains are inoperable and cannot be restored within 72 hours, 
then Mode 3 is prescribed within 6 hours and Mode 5 within 36 hours.
    Proposed Modification for End-State Required Actions: The end-state 
associated with Required Action B.2 of this LCO is being proposed to be 
changed from Mode 5 within 84 hours to Mode 4 within 60 hours, and the 
end-state associated with Required Action F.2 of this LCO is being 
proposed to be changed from Mode 5 within 36 hours to Mode 4 within 12 
hours.
    Assessment and Finding: In Mode 4 the release of stored energy to 
the RB would be only that associated with decay heat energy and energy 
stored in the RCS components. That is, over 95% of the energy assumed 
to be released to the RB during the DBA LOCA is associated with the 
core thermal power resulting from 100% full power. Since the reactor is 
already shut down, such a thermal release to the RB is not possible; 
only a small fraction of this energy could be released. Occurrence of 
the DBA, a 28 inch cold leg guillotine break at a RCP discharge, is 
considered to be very unlikely to occur at any time, much less while 
operating in Mode 4. Indeed, the occurrence of a LOCA of any kind 
during operation in this Mode is considered highly unlikely. Due to the 
redundancy of the containment spray and cooling systems, both their 
functions are available to control and maintain RB pressure well below 
the design limit; the function to remove radioactive iodine from the 
containment atmosphere will also be available.
    Because the energy that can be released to the RB when operating in 
Mode 4 is only a fraction of that associated with a DBA, RB pressure 
will be only slightly higher should a LOCA occur when operating in Mode 
4 as compared to when operating in Mode 5. For these reasons 
containment leakage is small and because significant radionuclide decay 
will have occurred, (i.e., because the plant has been shut down), no 
increase in LERF is expected.
    Plant risk is lower when operating in Mode 4 (not on SDC) than when 
operating in Mode 5; risk associated with SDC operation is avoided. 
Also, when operating in Mode 4 (not on SDC) there are more mitigation 
systems (e.g., HPI and EFW/AFW) available to respond to an IE that 
could challenge RCS inventory or decay heat removal, than when 
operating in Mode 5. These considerations ultimately lead to reduced 
challenges to the containment spray and cooling systems when operating 
in Mode 4 versus Mode 5. Therefore, the staff finds that the above 
requested change is acceptable.
3.2.11 LCO 3.7.7 Component Cooling Water (CCW) System
    This system provides cooling for ECCS equipment including EFW pumps 
that function to mitigate loss of feedwater IEs, and containment 
control equipment.
    LCO: Two CCW trains shall be operable.
    Condition Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.7.7 Condition B, Required Action B.2. 
Specifically, if a CCW train becomes inoperable and cannot be restored 
within 72 hours, then Mode 3 is prescribed within 6 hours and Mode 5 
within 36 hours.
    Proposed Modification for End-State Required Actions: The end-state 
associated with Required Action B.2 of this LCO is being proposed to be 
changed from Mode 5 within 36 hours to Mode 4 within 12 hours.
    Assessment and Finding: In Mode 4 the stored energy of the reactor 
system would be only that associated with reduced decay heat energy and 
energy stored in the RCS components. Because of this, heat loads on the 
CCW system will be greatly reduced from those associated with the DBA, 
i.e., a LOCA. Also, occurrence of a design bases LOCA is considered to 
be very unlikely to occur at anytime much less while operating in Mode 
4. Indeed, the occurrence of a LOCA of any kind during operation in 
this Mode is considered highly unlikely. Plant risk is lower when 
operating in Mode 4 (not on SDC) than when operating in Mode 5; risk 
associated with SDC operation is avoided. Also, when operating in Mode 
4 (not on SDC) there are more mitigation systems (e.g., HPI and EFW/
AFW) available to respond to an IE that could challenge RCS inventory 
or decay heat removal, than when operating in Mode 5. These 
considerations ultimately lead to reduced challenges to the CCW system 
when operating in Mode 4 versus Mode 5. Therefore, the staff finds that 
the above requested change is acceptable.
3.2.12 TS 3.7.8 Service Water System (SWS)
    This system provides cooling for equipment that supplies boron to 
the RCS, i.e., HPI and emergency boration system.
    LCO: Two SWS trains shall be operable.
    Condition Requiring Entry into End-State: This proposed end-state 
change is associated with LCO 3.7.8 Condition B, Required Action B.2. 
Specifically, if an SWS train becomes inoperable and cannot be restored 
within 72 hours, then Mode 3 is prescribed within 6 hours and Mode 5 
within 36 hours.
    Proposed Modification for End-State Required Actions: The end-state 
associated with Required Action B.2 of this LCO is being proposed to be 
changed from Mode 5 within 36 hours to Mode 4 within 12 hours.
    Assessment and Finding: In Mode 4 the stored energy of the reactor 
system would be only that associated with reduced decay heat energy and 
energy stored in the RCS components. Because of this, heat loads on the 
SWS will be greatly reduced from those associated with the DBA, i.e., a 
LOCA. Also, occurrence of a design bases LOCA is considered to be very 
unlikely to occur at anytime much less while operating in Mode 4. 
Indeed, the occurrence of a LOCA of any kind during operation in this 
Mode is considered highly unlikely. Plant risk is lower when operating 
in Mode 4 (not on SDC) than when operating in Mode 5; risk associated 
with SDC operation is avoided. Also, when operating in Mode 4 (not on 
SDC) there are more mitigation systems (e.g., HPI and EFW/AFW) 
available to respond to an IE that could challenge RCS inventory or 
decay heat removal, than when operating in Mode 5. These considerations 
ultimately lead to reduced challenges to the SWS when operating in Mode 
4 versus Mode 5, and

[[Page 65624]]

therefore, the staff finds that the above requested change is 
acceptable.
3.2.13 TS 3.7.9 Ultimate Heat Sink (UHS)
    The UHS provides a heat sink for process and operating heat from 
safety related components during a transient or accident as well as 
during normal operation. The UHS has been defined as that complex of 
water sources, including necessary retaining structures (e.g., a pond 
with its dam, or a river with its dam), and the canals or conduits 
connecting the sources with, but not including, the cooling water 
system intake structures. The two principal functions of the UHS are 
the dissipation of residual heat after a reactor shutdown, and 
dissipation of residual heat after an accident. The UHS is the sink for 
heat removal from the reactor core following all accidents and 
anticipated occurrences (AOs) in which the unit is cooled down and 
placed on DHR. Its maximum post accident heat load occurs approximately 
20 minutes after a design basis LOCA. Near this time, the unit switches 
from injection to recirculation and the containment cooling systems are 
required to remove the core de