Notice of Opportunity To Comment on Model Safety Evaluation on Technical Specification Improvement for Combustion Engineering Plants to Risk-Inform Requirements Regarding Selected Required Action End States Using the Consolidated Line Item Improvement Process, 23238-23252 [E5-2174]

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• NUCLEAR REGULATORY COMMISSION

[Federal Register Volume 70, Number 85 (Wednesday, May 4, 2005)]
[Notices]
[Pages 23238-23252]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E5-2174]


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NUCLEAR REGULATORY COMMISSION


Notice of Opportunity To Comment on Model Safety Evaluation on 
Technical Specification Improvement for Combustion Engineering 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) 
relating to changes in Combustion Engineering (CE) plant required 
action end state requirements in technical specifications (TS). 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 specifications changes, designated as TSTF-
422, related to Topical Report CE NPSD-1186, Rev. 00, ``Technical 
Justification for the Risk Informed Modification to Selected Required 
Action End States for CEOG PWRs,'' which was approved by an NRC SE 
dated July 17, 2001. Licensees of CE nuclear power reactors to which 
the models apply could then request amendments, confirming the 
applicability of the SE and NSHC determination to their reactors. The 
NRC staff is requesting comment on the model SE and model NSHC 
determination prior to announcing their availability for referencing in 
license amendment applications.

DATES: The comment period expires June 3, 2005. 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: Tom Boyce, Mail Stop: O-12H4, Division 
of Inspection Program Management, Office of Nuclear Reactor Regulation, 
U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, 
telephone 301-415-0184.

SUPPLEMENTARY INFORMATION:

Background

    Regulatory Issue Summary 2000-06, ``Consolidated Line Item 
Improvement Process for Adopting Standard Technical Specifications 
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 
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. This notice solicits comment on a proposed change to the STS 
that allows changes in CE plant required action end state requirements 
in technical specifications, if risk is assessed and managed. 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 involves the changes in CE plant required action end 
state requirements in TS, if risk is assessed and managed. The change 
was proposed in Topical Report CE NPSD-1186, Rev. 00, ``Technical 
Justification for the Risk Informed Modification to Selected

[[Page 23239]]

Required Action End States for CEOG PWRs,'' which was approved by an 
NRC SE dated July 17, 2001. This change was proposed for incorporation 
into the STS by the owners groups participants in the Technical 
Specification Task Force (TSTF) and is designated TSTF-422. TSTF-422 
can be viewed on the NRC's Web page at https://www.nrc.gov/reactors/
operating/licensing/techspecs.html.

Applicability

    This proposal to modify TS requirements by the adoption of TSTF-422 
is applicable to all licensees of CE plants who have adopted or will 
adopt, in conjunction with the proposed change, TS requirements for a 
Bases control program consistent with the TS Bases Control Program 
described in Section 5.5 of the applicable vendor's STS, and commit to 
WCAP-16364-NP, Rev [0], ``Implementation Guidance for Risk Informed 
Modification to Selected Required Action End States at Combustion 
Engineering NSSS Plants (TSTF-422).''
    To efficiently process the incoming license amendment applications, 
the staff requests that each licensee applying for the changes proposed 
in TSTF-422 include Bases for the proposed TS consistent with the Bases 
proposed in TSTF-422. In addition, licensees that have not adopted 
requirements for a Bases control program by converting to the improved 
STS or by other means, are requested to include the requirements for a 
Bases control program consistent with the STS in their application for 
the proposed change. The need for a Bases control program stems from 
the need for adequate regulatory control of some key elements of the 
proposal that are contained in the proposed Bases in TSTF-422. The 
staff is requesting that the Bases be included with the proposed 
license amendments in this case because the changes to the TS and the 
changes to the associated Bases form an integral change to a plant's 
licensing bases. To ensure that the overall change, including the 
Bases, includes appropriate regulatory controls, the staff plans to 
condition the issuance of each license amendment on the licensee's 
incorporation of the changes into the Bases document and on requiring 
the licensee to control the changes in accordance with the Bases 
Control Program. The CLIIP does not prevent licensees from requesting 
an alternative approach or proposing the changes without the requested 
Bases and Bases control program. However, deviations 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.

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 safety evaluation 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 plant 
required action end state requirements in technical specifications.

Proposed Safety Evaluation

U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor 
Regulation, Consolidated Line Item Improvement, Technical Specification 
Task Force (TSTF) Change TSTF-422, Risk Informed Modifications to 
Selected Required Action End States

1.0 Introduction

    On January 23, 2003, the Nuclear Energy Institute (NEI) Risk 
Informed Technical Specifications Task Force (RITSTF) submitted a 
proposed change, TSTF-422, Revision 1, to the Combustion Engineering 
(CE) standard technical specifications (STS) (NUREG-1432) on behalf of 
the industry. TSTF-422, Revision 1, is a proposal to incorporate the 
Combustion Engineering Owners Group (CEOG) approved Topical Report CE 
NPSD-1186, Rev. 00, ``Technical Justification for the Risk Informed 
Modification to Selected Required Action End States for CEOG PWRs'' 
(Reference 1), into the CE STS (Note: The proposed changes are made 
with respect to STS, Rev. 3, unless otherwise stated). This proposal is 
one of the industry's initiatives being 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 technical specifications 
(TS), while reducing unnecessary burden and making technical 
specification 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(c)(2)(i), ``Technical 
Specifications; Limiting Conditions for Operation,'' states: ``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 until the condition can be 
met.'' 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 shutdown. When 
the individual plant technical specifications were written, the 
shutdown condition or end state specified was usually cold shutdown.
    Topical Report CE NPSD-1186 provides the technical basis to change 
certain required end states when the TS CTs for remaining in power 
operation are exceeded. Most of the requested TS changes are to permit 
an end state of hot shutdown (Mode 4) rather than an end state of cold 
shutdown (Mode 5) contained in the current TS. The request was limited 
to: (1) Those end states where 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 TS for CE plants define six operational modes. In general, they 
are:
     Mode 1--Power Operation.
     Mode 2--Reactor Startup.
     Mode 3--Hot Standby. Reactor coolant system (RCS) 
temperature above 300[deg]F (TS specific) and RCS pressure that can 
range up to power operation pressure. Shutdown cooling (SDC) systems 
can sometimes be operated in the lower range of Mode 3 temperature and 
pressure.
     Mode 4--Hot Shutdown. RCS temperature can range from the 
lower value of Mode 3 to the upper value of Mode 5. Pressure is 
generally (but not always) low enough for SDC system operation.
     Mode 5--Cold Shutdown. RCS temperature is below 200[deg]F 
and RCS pressure is consistent with operation of the SDC system.
     Mode 6--Refueling. Operation is in Mode 6 if one or more 
reactor vessel head bolts have been de-tensioned. RCS

[[Page 23240]]

temperature is below 200[deg]F and RCS pressure is generally equal to 
containment pressure.
    Criticality is not allowed in Modes 3 through 6, inclusive.
    The CEOG request generally is to allow a Mode 4 end state rather 
than a Mode 5 end state for selected initiating conditions.

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)(1)-(5), TS are required to include items in the following five 
specific categories related to station 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 * * * .''
    The Reference 1 request states: ``preventing plant challenges 
during shutdown conditions has been, and continues to be, an important 
aspect of ensuring safe operation of the plant. Past events demonstrate 
that risk of core damage associated with entry into, and operation in, 
shutdown cooling is not negligible and should be considered when a 
plant is required to shutdown. Therefore, the TS should encourage plant 
operation in the steam generator heat removal mode whenever practical, 
and require SDC entry only when it is a risk beneficial alternative to 
other actions.''
    Controlling shutdown risk encompasses control of conditions that 
can cause potential initiating events and response to those initiating 
events that do occur. Initiating events are a function of equipment 
malfunctions and human error. Response to events is a function of plant 
sensitivity, ongoing activities, human error, defense-in-depth, and 
additional equipment malfunctions. In the end state changes under 
consideration here, a component or train has generally resulted in a 
failure to meet a TS and a controlled shutdown has begun because a TS 
CT requirement is not met.
    Most of today's shutdown TS and the design basis analyses were 
developed under the perception that putting a plant in cold shutdown 
would result in the safest condition and 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 a shutdown rule was expected, almost all TS changes 
involving power operation, including a revised end state requirement 
were postponed in anticipation of enactment of a shutdown rule (see, 
for example, Reference 2). However, in the mid 1990s, the Commission 
decided a shutdown rule was not necessary in light of industry 
improvements.
    In practice, the realistic needs during shutdown operation are 
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 
(Reference 5). The revised section 11 of NUMARC 93-01, Revision 2 , was 
subsequently incorporated into Revision 3 of NUMARC 93-01. However, 
Revision 3 has not yet been formally endorsed by the NRC.

3.0 Technical Evaluation

    The changes proposed in TSTF-422 are consistent with the changes 
proposed and justified in Topical Report CE NPSD-1186, and approved by 
the associated SE of July 17, 2001 (Reference 6). The evaluation 
included in Reference 6, as appropriate and applicable to the changes 
of TSTF-422 (Reference 7), is reiterated here and differences from the 
SE (Reference 6) are justified. [NOTE: Licensees must commit to WCAP-
16364-NP, Rev [0], ``Implementation Guidance for Risk Informed 
Modification to Selected Required Action End States at Combustion 
Engineering NSSS Plants (TSTF-422),'' (Reference 8) addressing a 
variety issues such as considerations and compensatory actions for risk 
significant plant configurations.] An overview of the generic 
evaluation and associated risk assessment will be provided, along with 
a summary of the associated TS changes justified by the SE (Reference 
6).

3.1 Risk Assessment

    The objective of the risk assessment in Topical Report CE NPSD-1186 
was to show that the risk changes due to changes in TS end states are 
either negative (i.e., a net decrease in risk) or neutral (i.e., no 
risk change).
    Topical Report CE NPSD-1186 documents a risk-informed analysis of 
the proposed TS changes. Probabilistic risk analysis (PRA) results and 
insights are used, in combination with results of deterministic 
assessments, to identify and propose changes in end states for all CE 
plants. This is consistent with guidance provided in RG 1.174, ``An 
Approach for Using Probabilistic Risk Assessment in Risk-Informed 
Decisions on Plant-Specific Changes to the Licensing Basis,'' 
(Reference 9), and RG 1.177, ``An Approach for Plant-Specific, Risk-
Informed Decisionmaking: Technical Specifications,'' (Reference 10). 
The three-tiered approach documented in RG 1.177 was followed. The 
first tier 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 (RG 1.174). In addition, the 
first tier aims at ensuring that there are no time intervals associated 
with the implementation of the proposed TS end state changes during 
which there is an increase in the probability of core damage or large 
early release with respect to the current end states. The second tier 
addresses the need to preclude potentially high-risk configurations 
which could result if equipment is taken out of service during 
implementation of the proposed TS change. The third tier addresses the 
application of 10 CFR 50.65(a)(4) for identifying risk-significant 
configurations resulting from maintenance or other operational 
activities and taking appropriate compensatory measures to avoid such 
configurations. The scope of the topical report and the associated SE 
were limited to identifying changes in end state conditions that 
excluded continued power operation as an acceptable end state, 
regardless of the risk.
    CEOG's risk assessment approach was found comprehensive and 
acceptable. In addition, the analyses show that the criteria of the 
three-tiered approach for allowing TS changes are met as explained 
below:

[[Page 23241]]

     Risk Impact of the Proposed Change (Tier 1). The risk 
changes associated with the proposed TS changes, 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 time intervals associated with the implementation of the 
proposed TS end state changes during which there is an increase in the 
probability of core damage or large early release with respect to the 
current end states.
     Avoidance of Risk-Significant Configurations (Tier 2). The 
need for some restrictions and enhanced guidance was determined by the 
specific TS assessments, documented in WCAP-16364-NP, Rev. 0, 
``Implementation Guidance for Risk Informed Modification to Selected 
Required Action End States at Combustion Engineering NSSS Plants (TSTF-
422),'' (Reference 8). These restrictions and guidance are intended to 
(1) preclude preventive maintenance and operational activities on risk-
significant equipment combinations, and (2) identify actions to exit 
expeditiously a risk-significant configuration should it occur. The 
licensees are expected to commit to following the implementation 
guidance in Reference 8. The staff finds that the proposed restrictions 
and guidance are adequate for preventing risk-significant plant 
configurations.
     Configuration Risk Management (Tier 3). These are programs 
in place to comply with 10 CFR 50.65(a)(4) to assess and manage the 
risk from proposed maintenance activities. These programs can support 
licensee decisionmaking regarding the appropriate actions to control 
risk whenever a risk-informed TS is entered.

3.2 Assessment of TS Changes

    The changes proposed in TSTF-422 are consistent with the changes 
proposed in topical report CE NPSD-1186 and approved by the NRC SE of 
July 17, 2001. Only those changes proposed in TSTF-422 are addressed in 
this SE. The SE information and justifications are not duplicated in 
this document; see ML011980047 in ADAMS for the topical report SE 
(Reference 6). The SE and associated topical report address the entire 
fleet of CE plants, and the plants adopting TSTF-422 must confirm the 
applicability of the changes to their plant. Following are the proposed 
changes, including a synposis of the STS LCO, the change, and a brief 
conclusion of acceptability.
3.2.1 TS 3.5.4--Refueling Water Storage Tank (RWST)
    The RWST is a source of borated water for the ECCS.
    LCO: The RWST shall be operable in Modes 1, 2, 3, and 4.
    Condition Requiring Entry into End State: When the RWST is 
inoperable in Modes 1, 2, 3, and 4 due to boron concentration not being 
within limits and not corrected within 8 hours.
    Proposed Modification for End State Required Actions: Modify action 
statement to allow for Mode 3 or Mode 4 end state when boron 
concentration is outside of the operating band for a period greater 
than 8 hours and create a new action (e.g., 3.5.4 D.2) to maintain the 
current end state for other inoperabilities than boron concentration 
out of limits.
    Assessment: The requested change is unlikely to have a significant 
impact on safety because deviations are likely to be small. Most of the 
need for a large volume of water from the RWST in Mode 3 is due to low 
probability events such as loss-of-coolant-accident (LOCA), and 
avoiding equipment transitions associated with some mode changes, and 
thereby avoiding risk associated with those changes.
3.2.2 TS 3.3.6--ESFAS Logic and Manual Trip--(Digital)
    The engineered safety feature actuation system (ESFAS) provides an 
automatic actuation of the ESFs which are required for accident 
mitigation. A set of two manual trip circuits is also provided, which 
uses the actuation logic and initiation logic circuits to perform the 
trip function.
    LCO: Six channels of ESFAS matrix logic, four channels of ESFAS 
initiation logic, two channels of actuation logic and two channels of 
manual trip shall be operable for the safety injection actuation signal 
(SIAS), containment isolation actuation signal (CIAS), containment 
cooling actuation signal (CCAS), recirculation actuation signal (RAS), 
containment spray actuation signal (CSAS), main steam isolation signal, 
and emergency feedwater actuation system EFAS-1 and EFAS-2. The LCO is 
applicable in Modes 1, 2, and 3 for all functions for all components 
and in Mode 4 for initiation logic, actuation logic, and manual trip 
for SIAS, CIAS, CCAS, and RAS. (The specific applicability of CCAS or 
equivalent systems (e.g., CSAS) may vary among utilities.)
    Condition Requiring Entry into End State: Condition F of the TS is 
entered when:
    1. One manual trip circuit, initiating logic circuit, or actuation 
logic circuit is inoperable for RAS, SIAS, CIAS, or CCAS, for more than 
48 hours (Conditions A, B & D), or,
    2. Two initiating logic circuits in the same trip leg for RAS, 
SIAS, CIAS, or CCAS are inoperable for more than 48 hours (Condition 
C).
    Proposed Modification for End State Required Actions: Modify the 
Mode 5 end state required action to allow component repair in Mode 4 of 
all functions of the CCAS and RAS initiation/logic function of the SIAS 
and CIAS. Entry into Mode 4 is proposed at 12 hours. No change was 
requested for TS 3.5.3, ECCS-shutdown.
    Assessment: The primary objective of the ESFAS logic and manual 
trip in Mode 4 is to provide a SIAS to the operable HPSI train and CIAS 
to ensure containment isolation. For TS 3.5.3, ECCS-Shutdown, to be 
met, the manual trip and actuation logic associated with that train of 
HPSI must be available in Mode 4. No other Mode 4 restrictions are 
required. By including the actuation logic in Mode 4, the effort in 
establishing HPSI following a LOCA or other inventory loss event is 
minimized. Similarly, by requiring one CIAS manual trip and actuation 
relay group to be operable, the plant operating staff does not have to 
operate every containment penetration manually following an event that 
may lead to radiation releases to the containment.
    In general, the CCAS is used to automatically actuate the 
containment heat removal systems (containment recirculation fan 
coolers) to prevent containment overpressurization during a range of 
accidents which release inventory to the containment, including large 
break LOCAs, small break LOCAs, or main steam line breaks or feedwater 
line breaks inside containment. This signal is typically actuated by 
high containment pressure. Based on the lower stored energy in the RCS 
and lesser core heat generation, short term containment pressure 
following a LOCA or main steam line break would be less than the 
current design containment strength. Ample instrumentation is available 
to the operator to diagnose the onset of the event and to take 
appropriate mitigating actions (actuation of the containment fan 
coolers and/or sprays) prior to a potential containment threat.
    Following a LOCA, the RAS is used to automatically perform the 
switchover from the SI mode of heat removal to the sump recirculation 
mode of heat removal. RAS times in Mode 4 are expected to be longer 
than those associated with Mode 1 and available instrumentation is 
sufficient to alert the operator to the need for switchover.

[[Page 23242]]

    Since the SIAS and CIAS signals perform numerous actions, manual 
trip and actuation for these signals should be retained in Mode 4. In 
particular, the operability of a single train of HPSI is required in 
Mode 4. Therefore, the associated actuation circuit and manual trip 
circuit for SIAS should be maintained available so that automatic 
lineup of HPSI can be established following a LOCA. Both isolation 
valves in the appropriate containment penetrations are required to be 
operable during Mode 4. However, the large number of actions required 
to isolate these penetrations, given an event, indicates that an 
extended unavailability of CIAS is not desired. We conclude from a 
comparison of plant conditions, event response, and risk 
characteristics, including the discussions of Sections 3 and 4 of 
Reference 6, that there is no net benefit from requiring a Mode 5 end 
state as opposed to a Mode 4 end state.
3.2.3 TS 3.3.8--(Digital) Containment Purge Isolation Signal
    The containment purge isolation signal (CPIS) provides automatic or 
manual isolation of any open containment purge valves upon indication 
of high containment airborne radiation.
    LCO: One CPIS channel shall be operable in Modes 1, 2, 3, and 4, 
during core alterations, and during movement of irradiated fuel 
assemblies within containment.
    Condition Requiring Entry into End State: CPIS (manual trip 
actuation logic), or one or more required channels of radiation 
monitors is inoperable and the required actions associated with the TS 
allowed outage time (AOT) or completion time (CT) have not been met.
    Proposed Modification for End State Required Actions: Modify Mode 5 
end state required action to allow component repair in Mode 4. Entry 
time into Mode 4 is proposed at 12 hours.
    Assessment: TS for Modes 1 through 4 allow plant operation with the 
containment mini-purge valves open. Following an accident, 
unavailability of the CPIS in Mode 4 would prevent automatic 
containment purge isolation. Without automatic isolation, the operator 
must manually isolate the containment purge. Since Mode 4 core damage 
events will evolve more slowly than similar events at Mode 1, the 
operator has adequate time and plant indications to identify and 
respond to an emergent core damage event and secure the containment 
purge.
    The staff addressed Mode 4 versus Mode 5 operation in Sections 3 
and 4 of Reference 6, and concluded there is essentially no benefit in 
moving to Mode 5 under many conditions. Further, there is a potential 
benefit to remaining in Mode 4 on SG heat removal because additional 
risk benefits are realized by averting the risks associated with the 
alignment of the SDC system.
    The CEOG recommended and provided implementation guidance stating 
that, when the CPIS is disabled, the operating staff should be alerted 
and operation of the containment mini-purge should be restricted. It 
further recommended consideration should be given to maintaining 
availability of CIAS during the CPIS Mode 4 repair. The staff endorses 
these recommendations. In addition, licensees must commit to the 
implementation guidance contained in Reference 8.
3.2.4 TS 3.3.8 (Analog) and TS 3.3.9--(Digital), Control Room Isolation 
Signal
    The control room isolation signal (CRIS) initiates actuation of the 
emergency radiation protection system and terminates the normal supply 
of outside air to the control room to minimize operator radiation 
exposure.
    LCO: One channel of CRIS shall be operable. The channel consists of 
manual trip, actuation logic, and radiation monitors for iodine/
particulates and gases.
    Condition Requiring Entry into End State: Both channels of CRIS are 
inoperable (and one control room emergency air cleanup system train is 
not realigned to the emergency mode within one hour). A channel 
consists of actuation logic, manual trip, and particulate/iodine and 
gaseous radiation monitors.
    Proposed Modification for End State Required Actions: It is 
proposed that the existing TS be modified to change the Mode 5 end 
state required action to allow component repair in Mode 4. Entry time 
into Mode 4 is 12 hours.
    Assessment: The CRIS includes two independent, redundant 
subsystems, including actuation trains. Control room isolation also 
occurs on a SIAS. The CRIS functions must be operable in Modes 1, 2, 3, 
and 4 [5, 6], [during core alterations], and during movement of 
irradiated fuel assemblies to ensure a habitable environment for the 
control room operators.
    This system responds to radiation releases from fuel. Adequate in-
plant radiation sensors (for example, containment high area radiation 
monitors (CHARMs)) are available to identify the need for control room 
(CR) isolation or shield building filtration (if appropriate). In Mode 
4, the transient will unfold more slowly than at power. Therefore 
sufficient time exists for the operator to take manual action to 
realign the control room emergency air cleanup system (CREACUS). The 
staff addressed Mode 4 versus Mode 5 operation in Sections 3 and 4 of 
Reference 6, and concluded there is essentially no benefit in moving to 
Mode 5 under many conditions, including this condition. Further, there 
is a potential benefit to remaining in Mode 4 on SG heat removal 
because additional risk benefits are realized by averting the risks 
associated with the alignment of the SDC system.
    The CEOG recommended and provided implementation guidance stating 
that it would be prudent to minimize unavailability of SIAS and 
alternate shutdown panel and/or remote shutdown capabilities during 
Mode 4 operation with CRIS unavailable. The staff agrees. In addition, 
licensees must commit to the implementation guidance contained in 
Reference 10.
3.2.5 TS 3.3.9--(Analog) Chemical Volume Control Isolation Signal
    The chemical volume control system (CVCS) isolation signal provides 
protection from radioactive contamination, as well as personnel and 
equipment protection in the event of a letdown line rupture outside 
containment.
    LCO: Four channels of west penetration room/letdown heat exchanger 
room pressure sensing and two actuation logic channels shall be 
operable.
    Condition Requiring Entry into End State: The Mode 5 end state 
entry (Condition D) is required when:
    1. One actuation logic channel is inoperable, or
    2. One CVCS isolation instrument channel is inoperable for a time 
period in excess of the plant AOT/CT (48 hours).
    Proposed Modification for End State Required Actions: Modify 
Condition D of TS to accommodate a Mode 4 end state when the required 
actions are not completed in the specified time.
    Assessment: Transition to lower temperature states requires the 
CVCS. Thus, by the time the plant is placed in Mode 4, the system 
should have successfully operated to borate the RCS. The CEOG stated 
that, consequently, there is adequate time to identify the need for 
CVCS isolation and for the operator to terminate letdown and secure 
charging.
    The staff addressed Mode 4 versus Mode 5 operation in Sections 3 
and 4 of Reference 6, and concluded there is essentially no benefit in 
moving to

[[Page 23243]]

Mode 5 under many conditions. Further, there is a potential benefit to 
remaining in Mode 4 on SG heat removal because additional risk benefits 
are realized by averting the risks associated with the alignment of the 
SDC system.
3.2.6 TS 3.3.10 (Analog)--Shield Building Filtration Actuation Signal
    The shield building filtration actuation signal (SBFAS) is required 
to ensure filtration of the air space between the containment and 
shield building during a LOCA.
    LCO: Two channels of SBFAS automatic and two channels of manual 
trip shall be operable.
    Condition Requiring Entry into End State: Shutdown Condition B of 
TS 3.3.10 requires transition to Mode 5. This required action is to be 
taken when one Manual Trip or Actuation Logic channel is inoperable for 
a time period exceeding the TS AOT/CT (48 hours).
    Proposed Modification for End State Required Actions: Modify Mode 5 
end state required action to allow component repair in Mode 4.
    Assessment: With one SBFAS channel inoperable, the system may still 
provide its function via its redundant channel. These systems provide 
post-accident radiation protection to on-site staff and/or the public. 
Since these systems respond to radiation releases from fuel, adequate 
in-plant radiation sensors (such as CHARMs) are available to identify 
the need for CR isolation or shield building filtration (if 
appropriate).
    The staff addressed Mode 4 versus Mode 5 operation in Sections 3 
and 4 of Reference 6, and concluded there is essentially no benefit in 
moving to Mode 5 under many conditions, including this condition. 
Further, there is a potential benefit to remaining in Mode 4 on SG heat 
removal because additional risk benefits are realized by averting the 
risks associated with the alignment of the SDC system.
3.2.7 TS 3.4.6--RCS Loops--Mode 4
    An RCS loop consists of a hot leg, SG, crossover pipe between the 
SG and an RCP, the RCP, and a cold leg. The operational meaning with 
respect to this TS is that water flows from the reactor vessel into a 
hot leg, either into a SG or a SDC system where it is cooled, and is 
returned to the reactor vessel via one or more cold legs. The flow rate 
must be sufficient to both cool the core and to ensure good boron 
mixing.
    LCO: Two loops or trains consisting of any combination of RCS loops 
and SDC trains shall be operable and at least one loop or train shall 
be in operation while in Mode 4.
    Condition Requiring Entry into End State: Condition B of the STS 
Revision 1 requires that with one required SDC train inoperable and two 
required RCS loops inoperable for 24 hours, the plant be maneuvered 
into Mode 5. Required Action A.2 of STS Revisions 2 and 3 require 
proceeding to Mode 5 within 24 hours with a required loop inoperable 
and a SDC loop operable (the STS Revision 1, 2 and 3 situations and 
results are similar, yet worded differently). The short completion time 
and the low-temperature end state reflect the importance of maintaining 
these paths for heat removal.
    Proposed Modification for End State Required Actions: When RCS 
loops are unavailable with the inoperability of one train of SDC, but 
at least one SG heat removal path can be established, modify the TS to 
change the end state from Mode 5 to Mode 4 with RCS heat removal 
accomplished via the steam generators.
    Assessment: This TS requires that two loops or trains consisting of 
any combination of RCS cooling loops or SDC trains shall be operable 
and at least one loop or train shall be in operation to provide forced 
flow in the RCS for decay heat removal and to mix boron. LCO action 
3.4.6 addresses the condition when the two SDC trains are inoperable. 
In that condition, the STS recognizes that Mode 5 SDC operation is not 
possible and continued Mode 4 operation is allowed until the condition 
may be exited. Condition B of STS Revision 2 and Required Action A.2 of 
STS Revision 3 are concerned with the unavailability of forced 
circulation in two RCS loops and the inoperability of one train of SDC. 
Upon failure to satisfy the LCO, the current STS drives the plant to 
Mode 5.
    The requested change reflects the risk of Mode 5 operation with one 
SDC system train inoperable and two RCS loops not in operation. The 
change will allow heat removal to be achieved in Mode 4 using either 
SDC or, if available, the steam generators with RCS/core heat removal 
driven by natural convection flows. Reactivity concerns are addressed 
by requiring natural circulation prior to RCP restart. Furthermore, as 
already noted in the STS Bases, if unavailability of RCS loops is due 
to single SDC train unavailability, staying in a state with minimal 
reliance on SDC is preferred (Mode 4) due to the diversity in RCS heat 
removal modes during Mode 4 operation.
3.2.8 TS 3.6.2--Containment Air Locks
    Containment air locks provide a controlled personnel passage 
between outside and inside the containment building with two doors/
door-seals in series with a small compartment between the doors. When 
operable, only one door can be opened at a time, thus providing a 
continuous containment building pressure boundary. The two doors 
provide redundant closures.
    LCO: [Two] containment air lock[s] shall be operable in Modes 1, 2, 
3, and 4.
    Condition Requiring Entry into End State: Entry into a Mode 5 end 
state is required when:
    1. One or more containment air locks with one containment air lock 
door inoperable or,
    2. One or more containment air locks with containment air lock 
interlock mechanism inoperable, or
    3. One or more containment air locks inoperable for other reasons, 
and
    4. The required action not completed within the specified AOT/CT.
    Proposed Modification for End State Required Actions: Modify TS to 
accommodate Mode 4 end state within the Condition D required Action to 
shutdown. Mode 4 entry is proposed within 12 hours of expiration of the 
specified AOT/CT for the conditions that require entry into Mode 4.
    Assessment: The TS requirements apply to Modes 1, 2, 3, and 4. 
Containment air locks are not required in Mode 5. The requirements for 
the containment air locks during Mode 6 are addressed in LCO 3.9.3, 
``Containment Penetrations.''
    Operability of the containment air locks is defined to ensure that 
leakage rates (defined in TS 3.6.1) will not exceed permissible values. 
These TS are entered when containment leakage is within limits, but 
some portion of the containment isolation function is impaired. The 
issue of concern is the appropriate action/end state for extended 
repair of an inoperable air lock where air lock doors are not 
functional. Changes to the TS are only requested for conditions when 
containment leakage is not expected to exceed that allowed in TS 3.6.1. 
For example, this means that the containment air locks must still be 
functional under expected conditions during Mode 4 operation.
    The staff addressed Mode 4 versus Mode 5 operation in Sections 3 
and 4 of Reference 6, and concluded there is essentially no benefit in 
moving to Mode 5 under many conditions, including this condition. 
Further, there is a potential benefit to remaining in Mode 4 on SG heat 
removal because

[[Page 23244]]

additional risk benefits are realized by averting the risks associated 
with the alignment of the SDC system.
3.2.9 TS 3.6.3--Containment Isolation Valves
    For systems that communicate with the containment atmosphere, two 
redundant isolation valves are provided for each line that penetrates 
containment. For systems that do not communicate with the containment 
atmosphere, at least one isolation valve is provided for each line.
    LCO: Each containment isolation valve shall be operable in Modes 1, 
2, 3, and 4.
    Condition Requiring Entry into End State: A required action to 
maneuver the plant into Mode 5 (Condition F) will occur when one or 
more penetration flow paths exist with one or more containment 
isolation valves inoperable [except for purge valve leakage and shield 
building bypass leakage not within limit] and the affected penetration 
flow path cannot be isolated within the prescribed AOT/CT.
    Proposed Modification for End State Required Actions: Modify TS to 
accommodate a Mode 4 end state (within 12 hours) for any penetration 
having one CIV inoperable.
    Assessment: Operability of the containment isolation valves ensures 
that leakage rates will not exceed permissible values. This LCO is 
entered when containment leakage is within limits but some portion of 
the containment isolation function is impaired (e.g., one valve in a 
two valve path inoperable or containment purge valves have leakage in 
excess of TS limits). The issue of concern in this TS is the 
appropriate action/end state for extended repair of an inoperable CIV 
when one CIV in a single line is inoperable. The assessment discussed 
in paragraph 3.2.8 above, is applicable and will not be repeated.
3.2.10 TS 3.6.4--Containment Pressure
    LCO: Containment pressure shall be controlled within limits during 
Modes 1, 2, 3, and 4.
    Condition Requiring Entry into End State: A Mode 5 end state 
transition is required to be initiated (Condition B) when the 
containment pressure is not within limits and the condition is not 
corrected within one hour.
    Proposed Modification for End State Required Actions: Modify 
Condition B of TS to accommodate a Mode 4 end state when the required 
actions are not completed in the specified time. Mode 4 entry is 
proposed at 12 hours.
    Assessment: The upper limit on containment pressure in this LCO 
results from a containment designed to respond to Mode 1 design basis 
accidents while remaining well within the structural material elastic 
response capabilities. This effectively maintains the containment 
design pressure about a factor of two or more below the minimum 
containment failure pressure. Consequently, small containment pressure 
challenges at the design basis pressure have a negligible potential of 
threatening containment integrity.
    The vacuum lower limit on containment pressure is typically set by 
the plant design basis and ensures the ability of the containment to 
withstand an inadvertent actuation of the containment spray (CS) 
system. The lower limit is of particular concern to plants with steel 
shell containment designs--plants with steel containment control the 
impact of CS actuation via use of vacuum breakers. Therefore, for 
plants with steel shell containments, if the lower limit pressure 
specification is violated, the operators are to confirm operability of 
the vacuum breakers. For all plants, when entering this action 
statement for violation of low containment pressure limit for a period 
projected to exceed one day, one containment spray pump is to be 
secured. The licensee shall commit to an implementation guide in which 
these actions will be prescribed. Aspects of the assessment discussed 
in paragraph 3.2.8 above, are applicable and will not be repeated.
3.2.11 TS 3.6.5--Containment Air Temperature
    LCO: Containment average air temperature shall be <= 120[deg]F in 
Modes 1, 2, 3, and 4.
    Condition Requiring Entry into End State: Condition B of this TS 
requires a Mode 5 shutdown when containment temperature is not within 
limits and is not corrected within the specified AOT/CT.
    Proposed Modification for End State Required Actions: Modify 
condition B of TS to accommodate a Mode 4 end state with a 12 hour 
entry time.
    Assessment: The upper limit on containment temperature is based on 
Mode 1 design basis analyses for containment structures and equipment 
qualification. The Mode 4 energy release is less than the maximum that 
could occur in Mode 1 and, consequently, initial Mode 4 post-accident 
containment temperature will be below the containment temperature limit 
employed in the plant design basis. Thus, temporary operation outside 
the bounds of the LCO would not be expected to challenge containment 
integrity. Aspects of the assessment discussed in paragraph 3.2.8 above 
are applicable, and will not be repeated.
3.2.12 TS 3.6.6--Containment Cooling Systems
    The containment building is typically provided with containment 
spray and containment cooling trains to control containment conditions 
following accidents that cause containment pressure or temperature 
upsets.
    LCO: Two CS trains and two containment cooling trains shall be 
operable in Modes 1, 2, [and] [3 and 4]. The time required for Mode 5 
entry varies from 30 to 36 hours for one component of the containment 
cooling system out of service. [For SONGS Units 2 and 3, unavailability 
of one or more CS train(s) will require the plant to transition to Mode 
4 in 84 hours.]
    Condition Requiring Entry into End State: Condition B requires Mode 
5 entry when the affected train is not returned to service within the 
TS AOT/CT. For SONGS 2 and 3 only, conditions 3.6.6.1 B and 3.6.6.1 F 
require Mode 4 entry within 84 hours.
    Proposed Modification for End State Required Actions: Modify 
condition B and F of TS to accommodate a Mode 4 end state. Entry time 
requirements are as follows:

------------------------------------------------------------------------
               Inoperability                      Required actions
------------------------------------------------------------------------
CS one train..............................  Mode 4-84 hrs.
Cont. Coolers two trains..................  Mode 4-36 hrs.
------------------------------------------------------------------------

    Assessment: Containment cooling is required to ensure long term 
containment integrity. Containment cooling TSs include LCO 3.6.6.--
containment spray and cooling systems, LCO 3.6.6A--credit taken for 
iodine removal by containment spray, and LCO 3.6.6B--credit not taken 
for iodine removal by containment spray.
    The design basis of the CS and cooling systems varies among the 
CEOG units. Most CEOG plants credit the CS and cooling systems for 
containment pressure and temperature control and one of the two systems 
for radioiodine removal. In these plants, typically, one train of CS is 
sufficient to effect radioiodine control and one train of CS and one 
train of fan coolers is sufficient to effect containment pressure and 
temperature control. The Palo Verde units are designed with only the CS 
system (containing full capacity redundant CS pumps) which it credits 
for both functions.
    Design and operational limits (and consequently the TSs) are 
established based on Mode 1 analyses. Traditionally, these analyses and 
limits

[[Page 23245]]

are applied to Modes 2, 3, and 4. Mode 1 analyses bound the other modes 
and confirm the adequacy of the containment cooling system to control 
containment pressure and temperature following limiting containment 
pipe breaks occurring at any mode. However, the resulting TS 
requirements generally become increasingly conservative as the lower 
temperature shutdown modes are traversed. Plants that do not require 
containment cooling in Mode 4 include St. Lucie Units 1 and 2 and Palo 
Verde Units 1, 2 and 3. SONGS Units 2 and 3, ANO 2, and St. Lucie Units 
1 and 2 do not require sprays to be operable in Mode 4.
    Inability to complete the repair of a single train of cooling 
equipment in the allotted AOT/CT presently requires transition to Mode 
5. This end state transition was based on the expectation of low Mode 5 
risks when compared to alternate operating states. As discussed in 
Sections 3 and 4 of Reference 6, Mode 4 is a robust operating mode when 
compared to Mode 5. Furthermore, when considering potential Mode 4 
containment challenge, the low stored energy and decay heat of the RCS 
(after 36 or 84 hours) support the proposed use of the containment 
cooling and radionuclide removal capability. Based on representative 
plant analyses performed in support of PRA containment success 
criteria, containment protection may be established via use of a single 
fan cooler. Qualitatively, a similar conclusion could be drawn for one 
train of CS. Consequently, in Mode 4, one train of containment coolers 
or one train of CS should provide adequate heat removal capability. 
Furthermore, for plants that credit CS for iodine removal, accidents 
initiated in Mode 4 should be adequately mitigated via one operable 
spray pump. Therefore, 84 hours requested to transition to Mode 4 with 
one CS train inoperable allows additional time to restore the 
inoperable CS train and is reasonable when considering the relatively 
low driving force for a release of radioactive material from the RCS. 
Further, the CEOG states that the requested 36 hours to transition to 
Mode 4 with both trains of containment cooling inoperable is 
reasonable, based on operating experience, to reach the required plant 
conditions from full power conditions in an orderly manner and without 
challenging plant systems. It also recognizes that at least one train 
of CS is available as a backup system.
3.2.13 TS 3.6.11--Shield Building
    The shield building is a concrete structure that surrounds the 
primary containment in some pressurized water reactors (PWRs). Between 
the primary containment and the shield building inner wall is an 
annular space that collects containment leakage that may occur 
following an accident. Following a LOCA, the shield building exhaust 
air cleanup system establishes a negative pressure in the annulus 
between the shield building and the steel containment vessel. Filters 
in the system then control the release of radioactive contaminants to 
the environment.
    LCO: In Modes 1, 2, 3, and 4, Condition A provides 24 hours to 
restore Shield building operability. If the shield building cannot be 
restored to operable status within the required completion time, the 
plant must be brought to Mode 5 within 36 hours.
    Condition Requiring Entry into End State: A Mode 5 end state, in 
Condition B, is required to be initiated when the shield building is 
inoperable for more than 24 hours.
    Proposed Modification for End State Required Actions: Modify Mode 5 
end state required action to allow component repair in Mode 4 with a 12 
hour Mode 4 entry requirement.
    Assessment: The LCO considers the limited leakage design of the 
containment and the probability of an accident occurring during the 
transition from Mode 1 to Mode 5. The purpose of maintaining shield 
building operability is to ensure that the release of radioactive 
material from the primary containment atmosphere is restricted to those 
leakage paths and associated leakage rates assumed in the accident 
analysis.
    Shield building ``leakage'' at or near containment design basis 
levels is not explicitly modeled in the PRA. The PRA implicitly assumes 
that containment gross integrity must be available. In the Level 2 
model, containment leakage is not considered to contribute to large 
early release even without a shield building. Were accidents to occur 
in Mode 4, resulting initial containment pressures would be less than 
the design basis analysis conditions and the shield building would be 
available to further limit releases. When Condition A of this TS can no 
longer be met, the plant must be shut down and transitioned to Mode 5.
    Inoperability of the shield building during Mode 4 implies leakage 
rates in excess of permissible values. Containment conditions following 
a LOCA in Mode 4 may result in containment pressures somewhat higher 
than in Mode 5, but since containment leakage is controlled via TS 
3.6.1, and no major leak paths should be unisolable, there should be no 
contribution to an increased LERF.
    The requirements stated in the LCO define the performance of the 
shield building as a fission product barrier. In addition, this TS 
places restrictions on containment air locks and containment isolation 
valves. The integrated effect of these TS is intended to ensure that 
containment leakage is controlled to meet 10 CFR part 100 limits 
following a maximum hypothetical event initiated from full power.
    Accidents initiated from Mode 4 are initially less challenging to 
the containment than those initiating from Mode 1. Furthermore, by 
having the plant in a shutdown condition in advance, fission product 
releases should be reduced. Thus, while leakage restrictions should be 
maintained in Mode 4, a condition in excess of that allowed in Mode 1, 
is anticipated to meet overall release requirements and therefore, Mode 
4 should be allowed to effect repair of the leak and then return the 
plant to power operation.
    The staff addressed Mode 4 versus Mode 5 operation in Sections 3 
and 4 of Reference 6, and concluded there is essentially no benefit in 
moving to Mode 5 under many conditions, including this condition. 
Further, there is a potential benefit to remaining in Mode 4 on SG heat 
removal because additional risk benefits are realized by averting the 
risks associated with the alignment of the SDCS.
3.2.14 TS 3.7.7--Component Cooling Water System \1\
---------------------------------------------------------------------------

    \1\ Terminology for cooling water systems vary between the CEOG 
plants.
---------------------------------------------------------------------------

    The CCW system provides cooling to critical components in the RCS 
and also provides heat removal capability for various plant safety 
systems, both at power and on SDC.
    LCO: Two CCW trains shall be operable in Modes 1, 2, 3, and 4.
    Condition Requiring Entry into End State: One CCW train inoperable 
and not returned in Condition A to service in TS AOT/CT, 72 hours.
    Proposed Modification for End State Required Actions: Modify 
Condition B of TS to accommodate a Mode 4 end state with a 12 hour 
entry requirement, rather than a Mode 5 end state.
    Assessment: The appropriate actions to be taken in the event of 
inoperabilities of the CCW system depend on the particular system 
function being compromised and the existence of backup water supplies.
    In the event of a design basis accident, one train of CCW is 
required to provide the minimum heat removal capability

[[Page 23246]]

assumed in the safety analysis for systems to which it supplies cooling 
water. The CCW system provides heat removal capability to the 
containment fan coolers, CS, and SDC. In addition, CCW provides cooling 
to the reactor coolant pumps. Other safety components may be cooled via 
CCW component flow paths. From an end state perspective, upon loss of 
part of the CCW, the plant should normally transition to a state where 
reliance on the CCW system is least significant. For San Onofre Units 2 
and 3, loss of one CCW train will degrade the plant's capability to 
remove heat via the affected SDC heat exchanger. Thus, once on SDC, an 
unrecovered failure of the second CCW train means no SDC system will 
remove decay heat and alternate methods, such as returning to SG 
cooling, must be used to prevent core damage. Provided component 
cooling is available to the RCPs, a Mode 4 end state with the RCS on SG 
heat removal is usually preferred to the Mode 5 end state on SDC heat 
removal, in part for this reason. The risk of plant operation in Mode 4 
on SG cooling may be less than for Mode 5 because the transient risks 
associated with valve misalignments and malfunctions may be averted by 
avoiding SDC entry.
    For conditions where CCW flow is lost to the RCP seals, reactor 
shutdown is required and the RCS loops operating TS is entered. Limited 
duration natural circulation operation is acceptable, but extended 
plant operation in the higher Mode 4 temperatures may degrade RCP seal 
elastomers. Mode 5 operation ensures adequately low RCS temperatures so 
that RCP seal challenges would be avoided. Therefore, use of the 
modified Mode 4 end state may not always be appropriate. Prior to entry 
into Mode 5 due to loss of CCW to RCP seals, the redundant CCW train 
should be confirmed to be operable and backup cooling water systems 
should be confirmed for emergency use. SG inventory should be retained 
to assure a diverse and redundant heat removal source if CCW should 
fail. The licensee shall commit to an implementation guide in which 
compensatory actions will be contained.
3.2.15 TS 3.7.8--Service Water System/Salt Water Cooling System/
Essential Spray Pond System/Auxiliary Component Cooling Water \2\
---------------------------------------------------------------------------

    \2\ Terminology for cooling water systems vary between the CEOG 
plants.
---------------------------------------------------------------------------

    This TS covers systems that provide a heat sink for the removal of 
process heat and operating heat from the safety-related components 
during a transient or design basis accident. This discussion is based 
on the SONGS 2 and 3 designation of the SWC system.
    LCO: Two SWC trains shall be operable in Modes 1, 2, 3, and 4.
    Condition Requiring Entry into End State: One SWC train inoperable 
and not restored to operability in Condition A within TS AOT/CT, 72 
hours.
    Proposed Modification for End State Required Actions: Modify 
Condition B of TS to accommodate a Mode 4 end state with a 12 hour 
entry requirement on steam generator heat removal.
    Assessment: The primary function of the SWC system is to remove 
heat from the CCW system. In this manner the SWC system also supports 
the SDC system. In some plants the SWC system or its equivalent 
provides emergency makeup to the CCW system and may also provide backup 
supply to the AFWS. For many plants, including San Onofre Units 2 and 
3, loss of one SWC system train will degrade the plant's capability to 
remove heat via the affected SDC heat exchanger. In this case, a Mode 4 
end state with the RCS on SG heat removal is preferred to Mode 5 with 
the RCS on SDC heat removal.
    At least one SWC train must be operable to remove decay heat loads 
following a design basis accident. SWC is also used to provide heat 
removal during normal operating and shutdown conditions. Two 100 
percent trains of SWC are provided, which provides adequate SWC flow 
assuming the worst single failure.
    SWC is required to support SDC when the plant is in Mode 4 on SDC 
or in Mode 5. Therefore, in conditions in which the other SWC train is 
inoperable, the one operable SWC train must continue to function. The 
staff notes much of the CCW discussion in paragraph 3.2.14 above, is 
also applicable here since long-term loss of SWC is, in effect, loss of 
CCW.
    Operation in Mode 4 with the steam generators available provides a 
decay heat removal path that is not directly dependent on SWC, although 
there are some long-term concerns such as RCP seal cooling. Overall, 
the proposed Mode 4 TS end state generally results in plant conditions 
where reliance on the SWC system is least significant. The licensee 
shall commit to an implementation guide in which compensatory actions 
will be contained.
3.2.16 TS 3.7.9--Ultimate Heat Sink \3\
---------------------------------------------------------------------------

    \3\ Calvert Cliffs designates the system as the salt water 
system; SWC performs the function of the ultimate heat sink at SONGS 
Units 2 and 3.
---------------------------------------------------------------------------

    The ultimate heat sink (UHS) system provides a heat sink for the 
removal of process and operating heat from the safety-related 
components during a transient or design basis accident. In some plants 
the UHS system provides emergency makeup to the CCW system and may also 
provide backup supply to the AFW system. For many plants, loss of one 
UHS system train such as would occur with the loss of a cooling fan 
tower, as in this TS, will degrade the plant's capability to remove 
heat via the affected SDC heat exchanger.
    LCO: The UHS shall be operable in Modes 1, 2, 3, and 4.
    Condition Requiring Entry into End State: One cooling tower 
inoperable and not restored to operability in Condition A within TS 
AOT/CT, 7 days.
    Proposed Modification for End State Required Actions: Modify 
Condition B of TS to accommodate a Mode 4 end state with a 12 hour 
entry requirement.
    Assessment: In Modes 1, 2, 3, and 4, the UHS system is a normally 
operating system which is required to support the OPERABILITY of the 
equipment serviced by the SWS and required to be operable in these 
modes. In Mode 5, the OPERABILITY requirements of the UHS are 
determined by the systems it supports.
    When the plant is in Mode 5, UHS is required to support shutdown 
cooling and the one operable cooling tower (in conditions in which the 
other train is inoperable) must continue to function. Operation in Mode 
4 with the steam generators available provides a decay heat removal 
path that is not dependent on UHS.
    The proposed Mode 4 TS end state results in plant conditions where 
the direct reliance on the UHS system is the least significant. The 
rationale applicable to paragraph 3.2.15 above, applies to this section 
as well. Further, we note we addressed Mode 4 versus Mode 5 operation 
in Sections 3 and 4 of Reference 6, and concluded there is essentially 
no benefit in moving to Mode 5 under many conditions, including this 
condition.
3.2.17 TS 3.7.10--Emergency Chilled Water System
    The emergency chilled water (ECW) system provides a heat sink for 
the removal of process and operating heat from selected safety-related 
air-handling systems during a transient or accident.
    LCO: Two ECW trains shall be operable in Modes 1, 2, 3, and 4.
    Condition Requiring Entry into End State: Mode 5 entry is required 
when one ECW train is inoperable and not returned to service in 
Condition A within the TS AOT/CT, 7 days.
    Proposed Modification for End State Required Actions: Modify 
Condition B

[[Page 23247]]

of TS to accommodate a Mode 4 end state with a 12 hour entry 
requirement.
    Assessment: The ECW system is actuated on SIAS and provides water 
to the heating, ventilation and air conditioning (HVAC) units of the 
ESF equipment areas (e.g., main control room, electrical equipment 
room, safety injection pump area). For most plant equipment, ECW is a 
backup to normal HVAC. For a subset of equipment, only ECW is 
available, but cooling is provided by both ECW trains.
    In Modes 1, 2, 3, and 4, the ECW system is required to be operable 
when a LOCA or other accident would require ESF operation. Two trains 
have not been required in Mode 5 because potential heat loads are 
smaller and the probability of accidents requiring the ECW system has 
been perceived as low.
    Because normal HVAC would be available in all non-loss of 1E bus 
situations, cooling to most plant equipment would remain available. 
Should an event occur during Mode 4, the post-accident heat loads would 
be reduced, potentially allowing more time for manual recovery actions, 
including alternate ventilation measures. Such measures could inc