AP1000 Design Certification Amendment, 82079-82103 [2011-33266]

Agencies

• NUCLEAR REGULATORY COMMISSION

[Federal Register Volume 76, Number 251 (Friday, December 30, 2011)]
[Rules and Regulations]
[Pages 82079-82103]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-33266]


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NUCLEAR REGULATORY COMMISSION

10 CFR Part 52

RIN 3150-AI81
[NRC-2010-0131]


AP1000 Design Certification Amendment

AGENCY: Nuclear Regulatory Commission.

ACTION: Final rule.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC or Commission) is 
amending its regulations to certify an amendment to the AP1000 standard 
plant design. The amendment replaces the combined license (COL) 
information items and design acceptance criteria (DAC) with specific 
design information, addresses the effects of the impact of a large 
commercial aircraft, incorporates design improvements, and increases 
standardization of the design. This action is necessary so that 
applicants or licensees intending to construct and operate an AP1000 
design may do so by referencing this regulation (AP1000 design 
certification rule (DCR)), and need not demonstrate in their 
applications the safety of the certified design as amended. The 
applicant for this amendment to the AP1000 design is Westinghouse 
Electric Company, LLC (Westinghouse).

DATES: The effective date of this rule is December 30, 2011. The 
incorporation by reference of certain material specified in this 
regulation is approved by the Director of the Office of the Federal 
Register as of December 30, 2011. The applicability date of this rule 
for those entities who receive actual notice of this rule is the date 
of receipt of this rule.

ADDRESSES: You can access publicly available documents related to this 
action (see Section VI. Availability of Documents) using the following 
methods:
     NRC's Public Document Room (PDR): The public may examine 
and have copied, for a fee, publicly available documents at the NRC's 
PDR, O1-F21, One White Flint North, 11555 Rockville Pike, Rockville, 
Maryland 20852.
     NRC's Agencywide Documents Access and Management System 
(ADAMS): Publicly available documents created or received at the NRC 
are available online in the NRC Library at https://www.nrc.gov/reading-rm/adams.html. From this page, the public can gain entry into ADAMS, 
which provides text and image files of the NRC's public documents. If 
you do not have access to ADAMS or if there are problems in accessing 
the documents located in ADAMS, contact the NRC's PDR reference staff 
at 1-(800) 397-4209, (301) 415-4737, or by email to 
pdr.resource@nrc.gov.
     Federal Rulemaking Web site: Public comments and 
supporting materials related to this final rule can be found at https://www.regulations.gov by searching on Docket ID NRC-2010-0131. Address 
questions and concerns regarding NRC dockets to Carol Gallagher; 
telephone at (301) 492-3668; email: Carol.Gallagher@nrc.gov.

FOR FURTHER INFORMATION CONTACT: Ms. Serita Sanders, Office of New 
Reactors, U.S. Nuclear Regulatory Commission, Washington, DC 20555-
0001; telephone at (301) 415-2956; email: serita.sanders@nrc.gov.

SUPPLEMENTARY INFORMATION:

I. Background
II. Summary of Analysis of Public Comments on the AP1000 Proposed 
Rule
    A. Overview of Public Comments
    B. Description of Key Structures of the AP1000 Design
    C. Significant Public Comments and Overall NRC Responses
III. Discussion
    A. Technical Evaluation of Westinghouse Amendment to the AP1000 
Design
    B. Changes to Appendix D
    C. Immediate Effectiveness of Final Rule: Provision of Actual 
Notice to Southern Nuclear Operating Company
IV. Section-by-Section Analysis
    A. Scope and Contents (Section III)
    B. Additional Requirements and Restrictions (Section IV)
    C. Applicable Regulations (Section V)
    D. Issue Resolution (Section VI)
    E. Processes for Changes and Departures (Section VIII)
    F. Records and Reporting (Section X)
V. Agreement State Compatibility
VI. Availability of Documents
VII. Voluntary Consensus Standards
VIII. Finding of No Significant Environmental Impact: Availability
IX. Paperwork Reduction Act Statement
X. Regulatory Analysis
XI. Regulatory Flexibility Act Certification
XII. Backfitting and Issue Finality
XIII. Congressional Review Act

I. Background

    Title 10 of the Code of Federal Regulations (10 CFR), Part 52, 
``Licenses, Certifications, and Approvals for Nuclear Power Plants,'' 
Subpart B, presents the process for obtaining standard design 
certifications. Section 52.63, ``Finality of standard design 
certifications,'' provides criteria for determining when the Commission 
may amend the certification information for a previously certified 
standard design in response to a request for amendment from any person.
    The NRC originally approved the AP1000 design certification in a 
final rule in 2006 (71 FR 4464; January 27, 2006). The final AP1000 DCR 
incorporates by reference Revision 15 of the design control document 
(DCD) (ADAMS Accession No. ML053460400), which describes the AP1000 
certified design. During its initial certification of the AP1000 
design, the NRC issued a final safety evaluation report (FSER) for the 
AP1000 as NUREG-1793, ``Final Safety Evaluation Report Related to 
Certification of the AP1000 Standard Design,'' in September 2004 (ADAMS 
Accession No. ML043570339) and Supplement No. 1 to NUREG-1793 (ADAMS 
Accession No. ML053410203).
    From March 2006 through May 2007, NuStart Energy Development, LLC 
(NuStart) \1\ and Westinghouse provided the NRC with a number of 
technical reports (TRs) for pre-application review of a possible 
amendment to the approved AP1000 certified design, in order to: (1) 
close specific, generically applicable COL information items 
(information to be supplied by COL

[[Page 82080]]

applicants/holders) in the AP1000 certified standard design; (2) 
identify standard design changes resulting from the AP1000 detailed 
design efforts; and (3) provide specific standard design information in 
areas or for topics where the AP1000 DCD was focused on the design 
process and acceptance criteria. TRs typically addressed a topical area 
(e.g., redesign of a component, structure or process) and included the 
technical details of a proposed change, design standards, analyses and 
justifications as needed, proposed changes to the DCD, and 
Westinghouse's assessment of the applicable regulatory criteria (e.g., 
the assessment of the criteria in 10 CFR part 52, Appendix D, Section 
VIII, ``Processes for Changes and Departures''). The NRC identified 
issues associated with the TRs and engaged Westinghouse in requests for 
additional information and meetings during the pre-application phase to 
resolve them.
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    \1\ The NuStart member companies are: Constellation Generation 
Group, LLC, Duke Energy Corporation, EDF-International North 
America, Inc., Entergy Nuclear, Inc, Exelon Generation Company, LLC, 
Florida Power and Light Company, Progress Energy, and Southern 
Company Services, Inc.
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    On May 26, 2007, Westinghouse submitted, via transmittal letter 
(ADAMS Accession No. ML071580757), an application to amend the AP1000 
DCR. The application included Revision 16 of the DCD (ADAMS Accession 
No. ML071580939). This application was supplemented by letters dated 
October 26 (ADAMS Accession No. ML073120415), November 2 (ADAMS 
Accession No. ML073090471), and December 12, 2007 (ADAMS Accession No. 
ML073610541), and January 11 (ADAMS Accession No. ML080150513) and 
January 14, 2008 (ADAMS Accession No. ML080220389). The application 
noted, in part, that:
    (1) Generic amendments to the design certification, including 
additional design information to resolve DAC and design-related COL 
information items, as well as design information to make corrections 
and changes, would result in further standardization and improved 
licensing efficiency for the multiple COL applications referencing the 
AP1000 DCR that were planned for submittal in late 2007 and early 2008.
    (2) Westinghouse, in conjunction with NuStart, has been preparing 
TRs since late 2005. These TRs were developed with input, review, 
comment, and other technical oversight provided by NuStart members, 
including the prospective AP1000 COL applicants. Submittal of these TRs 
to the NRC was initiated in March 2006. The TRs contain discussion of 
the technical changes and supplemental information that is used to 
support the detailed information contained in the DCD.
    In Attachment 2 to the May 26, 2007, application, Westinghouse 
identified the criteria of 10 CFR 52.63(a)(1) that apply to the changes 
described in each TR and associated COL information items, if 
applicable.
    On January 18, 2008, the NRC notified Westinghouse that it accepted 
the May 26, 2007, application, as supplemented, for docketing (Docket 
No. 52-006) and published a notice of acceptance (ADAMS Accession No. 
ML073600743) in the Federal Register (73 FR 4926; January 28, 2008). On 
September 22, 2008, Westinghouse submitted Revision 17 to the AP1000 
DCD. Revision 17 contained changes to the DCD that had been previously 
accepted by the NRC in the course of its review of Revision 16 of the 
DCD. In addition, Revision 17 proposed changes to DAC in the areas of 
piping design (Chapter 3), instrumentation and control (I&C) systems 
(Chapter 7) and human factors engineering (HFE) (Chapter 18).
    The NRC issued guidance on the finalization of design changes in 
Interim Staff Guidance (ISG) DC/COL-ISG-011, ``Finalizing Licensing-
basis Information,'' (ADAMS Accession No. ML092890623), which describes 
various categories of design changes that should not be deferred and 
those that should be included in the DCR.
    By letter dated January 20, 2010, Westinghouse submitted a list of 
design change packages that would be included in Revision 18 of the 
AP1000 DCD (ADAMS Accession No. ML100250873). A number of subsequent 
submittals were made by Westinghouse to narrow the focus of those 
design changes to the categories of changes that should not be 
deferred, as recommended by DC/COL-ISG-011.
    Revision 18 to the AP1000 DCD (ADAMS Accession Nos. ML103480059 and 
ML103480572) was submitted on December 1, 2010, and contains both 
proposed changes previously described in the design change packages and 
changes already accepted by the NRC in the review process of Revision 
17 to the AP1000 DCD.
    In the course of its ongoing review of the amendment application, 
the NRC determined that changes from information in Revision 15 to the 
DCD were needed. In response to NRC questions, Westinghouse proposed 
such changes. Once the NRC was satisfied with these DCD markups, they 
were documented in the advance safety evaluation report (SER) as 
confirmatory items (CIs). The use of CIs is restricted to cases where 
the NRC has reviewed and approved specific DCD proposals. With the 
review of Revision 18, the NRC has confirmed that Westinghouse has made 
those changes to the DCD accepted by the NRC that were not addressed in 
Revision 17 to the AP1000 DCD. For the final rule, the NRC has 
completed the review of the CIs and prepared a FSER reflecting that 
action. The CIs were closed based upon an acceptable comparison between 
the revised DCD text and the text required by the CI. As further 
discussed later, Revision 19 is the version being certified in the 
final rule.
    In order to simplify the NRC's review of the design change 
documentation, and to simplify subsequent review by the NRC's Advisory 
Committee on Reactor Safeguards (ACRS), the design changes pursuant to 
DC/COL-ISG-011 are reviewed in a separate chapter (Chapter 23) of the 
FSER. This chapter indicates which areas of the DCD are affected by 
each design change and the letters from Westinghouse that submitted 
them. In some cases, the NRC's review of the design changes reviewed in 
Chapter 23 may be incorporated into the chapters of the FSER where this 
material would normally be addressed because of the relationship 
between individual design changes and the review of prior DCD changes 
from Revisions 16 and 17 of the DCD.
    The Westinghouse Revision 18 DCD includes an enclosure providing a 
cross-reference to the DCD changes and the applicable 10 CFR 
52.63(a)(1) criteria. Revision 17 provides a similar cross-reference 
within the September 22, 2008, Westinghouse letter for those changes 
associated with the revised DCD. Revision 16, on the other hand, uses 
TRs to identify the DCD changes and lists the corresponding applicable 
10 CFR 52.63(a)(1) criteria via Westinghouse letter, dated May 26, 2007 
(Table 1). Revision 19 has a cross-reference similar to Revisions 17 
and 18.
    As of the date of this document, the application for amendment of 
the AP1000 design certification has been referenced in the following 
COL applications:

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                                                                .
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Vogtle, Units 3 and 4.........  Docket No. 05200025/6.  73 FR 33118.
Bellefonte Nuclear Station,     Docket Nos. 05200014/5  73 FR 4923.
 Units 3 and 4.
Levy County, Units 1 and 2....  Docket Nos. 05200029/   73 FR 60726.
                                 30.
Shearon Harris, Units 2 and 3.  Docket Nos. 05200022/3  73 FR 21995.
Turkey Point, Units 6 and 7...  Docket Nos. 05200040/1  74 FR 51621.

[[Page 82081]]

 
Virgil C. Summer, Units 2 and   Docket Nos. 05200027/8  73 FR 45793.
 3.
William States Lee III, Units   Docket Nos. 05200018/9  73 FR 11156.
 1 and 2.
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II. Summary of Analysis of Public Comments on the AP1000 Proposed Rule

A. Overview of Public Comments

    The NRC published the proposed rule amending the AP1000 DCR in the 
Federal Register on February 24, 2011 (76 FR 10269). The public comment 
period for the proposed rule closed on May 10, 2011. The NRC received a 
large number of comment submissions for the proposed rule (AP1000 
rulemaking) from members of the public, non-governmental organizations, 
and the nuclear industry. A comment submission means a communication or 
document submitted to the NRC by an individual or entity, with one or 
more distinct comments addressing a subject or an issue. A comment, on 
the other hand, refers to statements made in the submission addressing 
a subject or issue.
    The NRC received more than 13,500 comment submissions, which appear 
to be variations of two letters with largely similar content. These 
comment submissions also contained approximately 100 separate comments. 
The NRC also received 66 additional comment submissions containing over 
100 comments. Finally, the NRC received four ``petitions'' to suspend 
or terminate this rulemaking, which are being treated as public 
comments. The petitions set forth approximately 39 comments. As stated 
in the proposed rule, ``Comments received after May 10, 2011 will be 
considered if it is practical to do so, but assurance of consideration 
of comments received after this date cannot be given.'' The NRC 
determined that it was practical to consider comment submissions 
received on or before June 30, 2011. Five of the comment submissions 
were received after the 75-day comment period closed, and the NRC has 
addressed these late-filed comment submissions as part of this final 
rule (the numbers above reflect those late-filed comments, which were 
deemed practical to consider). These late comment submissions consisted 
of one petition, two submissions requesting the NRC to reconsider 
comments made during the initial AP1000 DC rulemaking, and two 
submissions with supplemental information to support suspending this 
rulemaking. The NRC also received several comment submissions after 
June 30, 2011. The NRC deemed that it was not practical to consider, in 
this rulemaking, comments received after June 30, 2011 and, therefore, 
does not provide responses to those comments. The NRC has briefly 
reviewed them to ensure that they contain no health and safety matters.
    There were several commenters in favor of completing the AP1000 
rulemaking, while some were unconditionally opposed to completing the 
proposed amendment to the AP1000 design. The vast majority of 
commenters favored delaying (in some fashion) the AP1000 amendment 
rulemaking until lessons are learned from the Fukushima Daiichi Nuclear 
Power Plant (Fukushima) accident that occurred on March 11, 2011, and 
the NRC applies the lessons learned to U.S. nuclear power plants, 
including the AP1000 design.
    Before responding to specific comments based upon the Fukushima 
Daiichi Nuclear Power Plant Event, the NRC is providing this discussion 
about the ongoing actions underway in response to this event. The 
Commission created a Near-Term Task Force (NTTF) to conduct an analysis 
of the lessons that can be learned from the event. The task force was 
established to conduct a systematic and methodical review of NRC 
processes and regulations to determine whether the NRC should make 
additional improvements to its regulatory system. The NTTF issued a 
report (ADAMS Accession No. ML111861807) evaluating currently available 
technical and operational information from the event, and presented a 
set of recommendations to the Commission. The task force concluded that 
continued operation and continued licensing activities do not pose an 
imminent risk to public health and safety. Among other recommendations, 
the NTTF supports completing the AP1000 design certification rulemaking 
activity without delay (see pages 71-72 of the report).
    In an August 19, 2011, Staff Requirements Memoranda (SRM) (ADAMS 
Accession No. ML112310021), the Commission set forth actions related to 
the NTTF report together with a schedule for the conduct of those 
actions. Two of those actions have been completed and are documented in 
the following reports: ``Recommended Actions to Be Taken Without Delay 
from the Near-Term Task Force Report,'' September 9, 2011 (SECY-11-
0124) (ADAMS Accession No. ML11245A127) and ``Prioritization of 
Recommended Actions To Be Taken In Response to Fukushima Lessons 
Learned,'' October 3, 2011 (SECY-11-0137) (ADAMS Accession No. 
ML11269A204).
    The NTTF recommendations relevant to the AP1000 design 
certification are limited to: Seismic and flooding protection 
(Recommendation 2); mitigation of prolonged station blackout 
(Recommendation 4); and enhanced instrumentation and makeup capability 
for spent fuel pools (Recommendation 7). The task force concluded that, 
by the nature of its passive design and inherent 72-hour coping 
capability, the AP1000 design has many of the features and attributes 
necessary to address the Task Force recommendations, and the NRC 
concludes that no changes to the AP1000 DCR are required at this time. 
Moreover, even if the Commission concludes at a later time that some 
additional action is needed for the AP1000, the NRC has ample 
opportunity and legal authority to modify the AP1000 DCR to implement 
NRC-required design changes, as well as to take any necessary action to 
ensure that holders of COLs referencing the AP1000 also make the 
necessary design changes.
    The NRC organized the comments on the AP1000 amendment into the 
following subject areas: Fukushima-related, shield building, 
containment, severe accident mitigation design alternative (SAMDA), 
spent fuel, environmental, other AP1000 topics, and general concerns. 
Some comments opposed the AP1000 rulemaking until purported shield 
building flaws are corrected. Many comments opposed completing the 
AP1000 rulemaking for reasons outside the scope of this rulemaking. For 
example, many comments opposed the completion of the AP1000 rulemaking 
until there is resolution of high level radioactive waste storage 
issues.
    Due to the large number of comments received and the length of the 
NRC responses provided, this section of the statement of considerations 
(SOC) for the final rule amending the AP1000 design certification only 
provides a summary of the categories of comments with a general 
description of the resolution of those comments. A detailed description 
of comments and the NRC's response is contained in a comment response 
document, which is available electronically through ADAMS Accession No. 
ML113480018.

[[Page 82082]]

B. Description of Key Structures of the AP1000 Design

    This section is provided to help readers understand the issues and 
the NRC's responses. The following is a brief description of the three 
design features that were commented on, and a summary of the design 
changes that are being approved by the AP1000 amendment.
Containment
    The containment vessel is a single steel pressure vessel, inside 
which is located the reactor vessel with the nuclear fuel, the steam 
generators, the refueling water storage tank, and various equipment for 
power generation, refueling, and emergency response, and supporting 
electric power, control, and communications equipment.
    The steel containment building stands independently inside the 
shield building. The containment's primary purpose is to retain 
pressure up to the maximum ``design pressure'' should an accident occur 
in which the reactor vessel or associated equipment releases reactor 
coolant into the containment atmosphere. The containment also acts as 
the passive safety-grade interface to the ultimate heat sink.
    The primary containment vessel prevents the uncontrolled release of 
radioactivity to the environment. The AP1000 primary containment 
consists of a cylindrical steel shell with ellipsoidal upper and lower 
heads. The steel thickness is increased in the transition region where 
the cylindrical shell enters the foundation concrete to provide 
additional margin in consideration of corrosion.
    Safety-related coatings are applied to both the interior and 
exterior surfaces of the containment vessel. These coatings have 
several functions. For the exterior surface, the corrosion-resistant 
paint or coating for the containment vessel is specified to enhance 
surface wetability and film formation, as well as for corrosion 
protection. Wetability and film formation are important to the passive 
cooling function. For the interior containment surfaces, the coatings 
are designed to remain intact within the zone-of-influence of any 
postulated pipe break (or to result in settling of any resultant 
debris) to facilitate heat transfer to the containment vessel and for 
corrosion protection. Periodic inspections are required of the 
containment internal and external surfaces and of the coatings on those 
surfaces.
    As the interface to the ultimate heat sink (the surrounding 
atmosphere), the primary containment is an integral component of the 
passive containment cooling system. The exterior of the containment 
vessel provides a surface for evaporative film cooling and works in 
conjunction with the natural draft airflow created by the shield 
building baffle and chimney arrangement to reduce the pressure and 
temperature of the containment atmosphere following a design-basis 
accident (DBA). The source of water for the evaporative cooling is the 
passive containment cooling water storage tank, located at the top of 
the shield building.
    Design changes within the scope of the amendment with respect to 
the containment vessel are certain details about coatings with respect 
to long-term core cooling capability and the calculated peak accident 
pressure (from correction of errors). Other changes included addition 
of a vacuum relief system to provide protection for external pressure 
events.
Shield Building
    The shield building performs multiple functions (e.g., to provide a 
biological shield to high-energy radiation, to support the primary 
containment cooling water storage tank on the roof, to shield the steel 
containment from high-velocity debris that may be generated by 
tornadoes or other natural phenomena, to protect the containment from 
aircraft impact, and to function as a ``chimney'' to enhance airflow 
over the primary steel containment to remove heat from the containment 
and reduce containment pressure in the event that post-accident cooling 
of the containment would be necessary). While other designs have 
included shield buildings of reinforced concrete, with the exception of 
the AP600 design, they did not perform cooling functions. The shield 
building is not intended to be a pressure retaining structure or to 
mitigate the effects of a containment failure. The shield building 
construction is primarily a steel-concrete composite module wall, with 
a reinforced concrete roof and reinforced concrete where the wall meets 
the foundation. The wall is appropriately reinforced and sized where 
the composite wall module joins the reinforced concrete sections and as 
appropriate to accommodate seismic loads and aircraft loads. This 
design is new to the amendment; previously the structure was all 
reinforced concrete.
    The shield building and the containment are designed with a gap, or 
annulus, that ensures that both the shield building and steel 
containment are physically separate, excluding their foundation, and 
are considered to be ``freestanding.'' In the shield building, air 
flows from the environment through openings in the shield building 
wall. The air then flows down along an interior baffle, turns toward 
the steel containment vessel, and then rises alongside the steel 
containment vessel where it absorbs heat. This heated air naturally 
rises and is then exhausted through the chimney located in the center 
of the primary containment cooling water storage tank.
    Design changes to the passive containment cooling system and shield 
building principally involve the redesign of the shield building to a 
steel-composite design, with related changes to air inlet sizing, 
height of the building, and gratings above the chimney opening. Revised 
safety analyses were performed to confirm adequate containment pressure 
control, capability of the shield building to withstand external events 
(tornado, seismic), as well as aircraft impact assessment. The shield 
building functions to protect the containment and facilitate passive 
containment cooling were not changed in the current amendment.
Spent Fuel Pool
    The spent fuel pool (SFP) is a safety-related structure that is 
housed in the auxiliary building, which provides protection from 
aircraft impact or other external hazards.
    For the first 72 hours after loss of normal SFP cooling, including 
response to a station blackout (SBO) event, the SFP relies upon the 
natural heat capacity of the water in the pool to absorb the heat from 
spent fuel elements, and boil the water in the pool. Thus, the safety-
related means of heat removal for 72 hours is by heat-up of the volume 
of water in the pool and in safety-related water sources such as the 
cask washdown pit. The AP1000 design (as initially certified) included 
safety-related water level indication with readout and alarm in the 
main control room. A nonsafety-related spent fuel pool cooling system 
is also installed. Onsite, protected sources of water are available for 
up to 7 days, controlled from areas away from the pool. During high 
heat load conditions in the pool, two sources of alternating current 
(ac) power are required to be available. Water can be sprayed into the 
pool from two nozzle headers on opposite sides of the pool. A cross-
connection also exists to the residual heat removal system. Those 
design features needed to provide make-up water after 72 hours and up 
to 7 days, such as the passive containment cooling water ancillary 
storage tank, and ancillary diesel generators, are protected from 
external hazards including the

[[Page 82083]]

safe-shutdown earthquake (SSE), tornado, and flooding.
    Design changes within the scope of the current amendment are the 
number of fuel assemblies stored, the rack designs for new and spent 
fuel storage, the criticality analysis for spent fuel in the pool 
(including use of boron material attached to the storage cells), 
installation of spray headers, and credit for additional water sources 
for pool makeup.

C. Significant Public Comments and Overall NRC Responses

    Comment: Many comments noted the NRC staff nonconcurrence on the 
shield building design and requested that the NRC should reconsider the 
views expressed in the nonconcurrence.
    NRC Response: The NRC disagrees with these comments. Professional 
opinions may vary, and the NRC has mechanisms in place for making 
differing views known.
    NRC employees can choose to exercise the nonconcurrence process as 
a way of communicating their views and ensuring their opinions are 
heard by NRC management. The NRC staff individual who authored the 
nonconcurrence used this open process to express concerns regarding the 
safety of the AP1000 shield building design. The specific concerns and 
staff response to the nonconcurrence are publically available (ADAMS 
Accession No. ML103370648).
    The NRC concluded that the AP1000 shield building design is safe, 
meets the Commission's regulations, and provides reasonable assurance 
that the building will remain functional under design-basis loads. The 
comments did not offer new information on the matters related to the 
nonconcurrence nor did they include a rationale showing the NRC's 
resolution of the technical matters raised in the nonconcurrence to be 
incorrect. No change was made to the final rule, DCD, or environmental 
assessment (EA) as a result of these comments.
    Comment: One comment noted that the spent fuel racks' design in 
Revision 18 increased the density. The higher density fuel pools 
require boron shields between stored assemblies to reduce the risk of 
criticality. The comment stated that such re-racking introduces 
potential partial loss of cooling water, possible fire of spent fuel 
assemblies, and release of large inventories of cesium-137 and other 
radionuclides.
    NRC Response: The NRC agrees that, under the proposed amendment of 
the AP1000 DCR, the capacity of the spent fuel pool racks would be 
increased from 619 to 889 (rather than 884 as asserted by the comment) 
fuel assemblies, and that the increased density of fuel assemblies 
being stored in the spent fuel pool requires the use of boron shields 
as part of the amendment.
    However, the NRC disagrees with this comment's assertion that the 
increased capacity and density would introduce potential loss of 
cooling water, resulting in a possible fire of spent fuel assemblies 
and large releases of radionuclides. The comment did not explain how 
increased fuel capacity and concomitant increase in density of the 
spent fuel pool would ``introduce'' potential loss of cooling water as 
compared with the capacity and density described in DCD Revision 15. 
The NRC does not believe that the increased capacity and density leads 
to a new (previously un-described or unconsidered) way of losing spent 
fuel pool cooling water. The NRC evaluated the proposed increase in 
fuel assembly capacity and density, and the effectiveness of the 
Westinghouse-proposed boron shields to ensure against re-criticality of 
the spent fuel stored in the spent fuel pool. The AP1000 DCD Revision 
18 SFP criticality analysis was reviewed following the guidance found 
in NUREG-0800 Section 9.1.1, Revision 3, ``Criticality Safety of Fresh 
and Spent Fuel Storage and Handling,'' to ensure that the applicant is 
in compliance with the applicable regulations (General Design Criterion 
62, ``Prevention of Criticality in Fuel Storage and Handling,'' and 10 
CFR 50.68, ``Criticality Accident Requirements''). These requirements 
are generally performance-based with limitations on the reactivity 
values, and as such, there are no specific physical design requirements 
such as minimum geometric spacing which must be met. The AP1000 SFP 
criticality analysis demonstrates that, with the proposed storage 
arrangement of the SFP, the reactivity requirements are met, and no 
regulations are violated. Therefore, the NRC determined that that the 
AP1000 spent fuel pool storage arrangement is acceptable. No change was 
made to the rule, the DCD, or the EA as a result of this comment.
    Comment: Several comments stated that given the recent event at the 
Fukushima plant in Japan, the 75-day comment period is not adequate and 
should be extended.
    NRC Response: The NRC disagrees with this comment, and believes 
that the 75-day public comment period, which is consistent with most 
other NRC technical rulemakings, is adequate. The Commission 
established a NTTF to review relevant NRC regulatory requirements, 
programs, and processes, and their implementation, and to recommend 
whether the agency should make near-term improvements to its regulatory 
system. The public comment period for the proposed rule on the AP1000 
design certification amendment closed on May 10, 2011, and the NTTF 
issued its report (ML111861807) on July 12, 2011. The NTTF considered 
the AP1000 design certification amendment in its report and noted that 
it has passive safety systems. By nature of their passive designs and 
inherent 72-hour coping capability for core, containment, and spent 
fuel pool cooling, the AP1000 designs have many of the design features 
and attributes necessary to address the NTTF recommendations. The NTTF 
supports completing the AP1000 design certification rulemaking 
activities without delay.
    The NRC believes that the AP1000 final rulemaking can and should 
proceed without extending the public comment period because: (i) The 
NRC has determined that the AP1000 design certification amendment meets 
current regulations; (ii) the NRC will provide an opportunity for the 
public to provide input on NTTF recommendations, and (iii) if the NRC 
imposes additional requirements on the AP1000 design, existing 
regulations already define the process for doing so. No change was made 
to the rule, the DCD, or the EA as a result of this comment.
    Comment: One comment questioned whether the NRC endorsed NQA-1-1994 
for work performed for the AP1000 project, where the NRC documented 
that NQA-1-1994 adequately meets the NRC requirements in the Code of 
Federal Regulations, and whether the Westinghouse's AP1000 design meets 
the requirements of 10 CFR Part 50, Appendix B.
    NRC Response: The NRC has, in application-specific requests for NRC 
approval of quality assurance programs, approved the use of NQA-1-1994 
as an acceptable method to meet the requirements of Appendix B to 10 
CFR Part 50. The NRC's approvals of NQA-1-1994 have been documented in 
NRC SERs on those requests.
    The NRC believes that the AP1000 design meets the requirements of 
10 CFR Part 50, Appendix B. By letter dated February 23, 1996 (ADAMS 
Accession No. ML11280A309), the NRC issued a safety evaluation report 
approving Revision 1 of the Westinghouse Quality Systems Manual 
(Westinghouse Quality Assurance (QA) Manual). The Westinghouse QA 
Manual is based upon the guidance in NQA-1-1994. The NRC found that the 
Westinghouse QA Manual meets all the

[[Page 82084]]

requirements of Appendix B. In addition, the NRC concluded in its FSER 
for the amendment that Revision 5 of the Westinghouse Quality Systems 
Manual, as described in the AP1000 Design Control Document, Revision 
17, meets the criteria of Appendix B with respect to AP1000 quality 
assurance. No change was made to the final rule, the DCD, or the EA as 
a result of this comment.
    Comment: Several comments claimed the containment design was flawed 
because the containment cooling method includes convective air flow and 
because the steel containment could be subject to corrosion. As a 
result, they state that Westinghouse has not satisfactorily proved that 
the thin steel containment shell over the reactor would be effective 
during severe accidents.
    NRC Response: The NRC considers these comments to be outside the 
scope of the rulemaking amending the AP1000 DCR. These features of the 
AP1000 design that demonstrate that the containment shell would be 
effective during severe accident conditions, as well as resistant to 
corrosion have already been certified with Revision 15. The proposed 
amendment to the AP1000 design does not propose any modification to 
these features and, therefore, the comment is outside the scope of this 
rulemaking.
    The NRC considers a single metal containment vessel to be 
acceptable if it meets the requirements of the American Society of 
Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section 
III, Subsection NE. This part of the ASME Code contains requirements 
for the material, design, fabrication, examination, inspection, 
testing, and overpressure protection of metal containment vessels. Many 
such vessels are in use at operating nuclear power plants. The AP1000 
containment is designed to meet ASME requirements for a pressure of 6.9 
kPa (59 psi) and a temperature of 149 degrees C (300 degrees F). Its 
thickness includes an allowance for corrosion that may occur over the 
60-year design life of the plant.
    The AP1000 containment building has an additional function--
transferring heat from containment to the atmosphere. The staff has 
reviewed the applicant's analysis, which shows that the containment 
building and the shield building, working as a system, would transfer 
heat to the atmosphere during severe accidents as well as design-basis 
earthquakes. Experiments were conducted to demonstrate that these 
predictions are based upon physical phenomena that can be relied upon 
to work even when there is no ac power. In short, Westinghouse has 
demonstrated that the containment building is robust and will perform 
its safety functions effectively if a severe accident occurs at an 
AP1000 plant.
    The commenters did not offer any basis for Westinghouse to revise 
its design or for the NRC to revise its evaluation. No change was made 
to the final rule, the DCD, or the EA as a result of these comments.
    Comment: Many comments stated that Westinghouse has not proven that 
the reactor could be properly cooled in conditions similar to those at 
Fukushima.
    NRC Response: The NRC considers these comments to be outside the 
scope of the rulemaking amending the AP1000 DCR. The Fukushima event 
involved an extended SBO (loss of offsite and onsite ac power). 
Westinghouse has shown that the AP1000 includes design features that 
keep the reactor properly cooled under these conditions. The features 
of the AP1000 design ensuring that the reactor can be properly cooled 
in an extended SBO are already part of the certified design for the 
AP1000, and are not being changed or modified by this final rule 
amending the AP1000 design. Therefore, these comments are out of scope 
for this rulemaking.
    In addition, even if these comments are assumed to be within the 
scope of the rulemaking, the NRC disagrees with the comment. If a 
severe accident occurs, seriously damaging the core, the AP1000 
containment can be adequately cooled for 3 days--even if a loss-of-
coolant accident (LOCA) occurred and without any ac power--because the 
AP1000 containment is cooled by gravity-fed water from a tank located 
at the top of the containment. After 3 days with no ac power, only a 
small ``ancillary'' generator is needed. This generator is used to 
power a small pump that re-fills the tank that supplies water to the 
outside surface of the containment. The generator could be brought to 
the site; however, in an AP1000 design, two such generators are 
installed in a seismically qualified structure (along with fuel and 
supporting equipment). After 1 week, the containment can be cooled 
indefinitely as long as fuel for at least one ancillary generator is 
provided and there is water to replenish the water tank above the 
shield building, as discussed in the DCD.
    These comments did not present any basis that would support an NRC 
determination that the AP1000 design is deficient in this regard. No 
change was made to the final rule, the DCD, or the EA as a result of 
these comments.
    Comment: Some comments stated that there are significant unresolved 
technical issues related to Revision 19 changes and that the NRC has 
not fully disclosed its analysis of these weaknesses, and the existence 
of such weaknesses is evidenced by the concerns identified by Dr. Susan 
Sterrett, Mr. Arnie Gundersen of Fairewinds Associates, and Dr. John 
Ma.
    NRC Response: The NRC disagrees with this comment. As discussed in 
more detail in the comment response document, the NRC concludes these 
issues were either resolved as part of the initial AP1000 rulemaking, 
or are resolved as part of this rulemaking. Elsewhere in this notice, 
NRC discusses the Revision 19 changes and summarizes the response to 
the other technical issues.
    Comment: Many comments expressed views that nuclear power plants 
are too expensive or too dangerous, or that alternative energy sources 
should be pursued.
    NRC Response: The NRC considers these comments to be outside the 
scope of the rulemaking amendment the AP1000 DCR. The NRC has concluded 
that the AP1000 design meets its regulatory requirements, and the 
comments do not offer any basis that this is not supported. Other 
issues about expense or alternative energy sources are outside the 
scope of the rulemaking amending the AP1000 DCR. A design certification 
rule is not an NRC license or authorization for construction or 
operation. No change was made to the final rule, the DCD, or the EA as 
a result of these comments.
    Comment: Many comments expressed concerns about nuclear waste.
    NRC Response: These comments address matters that are outside the 
scope of the rulemaking amending the AP1000 DCR. These comments do not 
address whether the AP1000 design changes, as reflected in the 
amendment application and evaluated in the NRC's SER and EA, meet the 
applicable NRC requirements. No change was made to the final rule, the 
DCD, or the EA as a result of these comments.

III. Discussion

A. Technical Evaluation of Westinghouse Amendment to the AP1000 Design

    Westinghouse's request to amend the AP1000 design contained several 
classes of changes. Each class is discussed below:
Editorial Changes
    Westinghouse requested changes to the AP1000 DCD to correct 
spelling,

[[Page 82085]]

punctuation, grammar, designations, and references. None of these 
changes make substantive changes to the certified design, and NUREG-
1793, ``Final Safety Evaluation Report Related to Certification of the 
AP1000 Standard Design,'' Supplement 2 (SER) does not address these 
changes.
Changes To Address Consistency and Uniformity
    Westinghouse requested changes to the currently-approved AP1000 DCD 
(Revision 15) to achieve consistency and uniformity in the description 
of the certified design throughout the DCD. For example, a change to 
the type of reactor coolant pump (RCP) motor is evaluated in Chapter 5 
of the SER on the application for the AP1000 amendment; Westinghouse 
requested that wherever this RCP motor is described in the DCD, the new 
description of the changed motor be used. The NRC reviewed the proposed 
change (to be used consistently throughout the DCD) to ensure that the 
proposed changes needed for uniformity and consistency are technically 
acceptable and do not adversely affect the previously approved design 
description. The NRC's bases for approval of these changes are set 
forth in the SER for the AP1000 amendment.
    Substantive Technical Changes to the AP1000 Design (other than 
those needed for compliance with the AIA rule)
    Among the many technical changes to the currently-approved DCD 
Revision 15 that are proposed by Westinghouse for inclusion in Revision 
19 of the AP1000 DCD, the NRC selected 15 substantive changes for 
specific discussion in this final rule document, based on their safety 
significance:
     Removal of HFE DAC from the DCD.
     Change to I&C DAC and Inspections, Tests, Analyses, and 
Acceptance Criteria (ITAACs).
     Minimization of Contamination.
     Extension of Seismic Spectra to Soil Sites and Changes to 
Stability and Uniformity of Subsurface Materials and Foundations.
     Long-Term Cooling.
     Control Room Emergency Habitability System.
     Changes to the Component Cooling Water System (CCWS).
     Changes to I&C Systems.
     Changes to the Passive Core Cooling System (PCCS)--Gas 
Intrusion.
     Integrated Head Package (IHP)--Use of the QuickLoc 
Mechanism.
     Reactor Coolant Pump Design.
     Reactor Pressure Vessel (RPV) Support System.
     SFP Decay Heat Analysis and Associated Design Changes.
     Spent Fuel Rack Design and Criticality Analysis.
     Vacuum Relief System.
    The NRC evaluated each of the proposed changes and concluded that 
they are acceptable. The NRC's bases for approval of these changes are 
set forth in the FSER for the AP1000 amendment and are summarized in 
Section XII, ``Backfitting and Issue Finality,'' of this document, as 
part of the discussion as to how each of the 15 changes satisfy the 
criteria in 10 CFR 52.63(a).
Changes To Address Compliance With the AIA Rule
    Westinghouse requested changes to the AP1000 design in order to 
comply with the requirements of the AIA rule, 10 CFR 50.150. The NRC 
confirmed that Westinghouse has adequately described key AIA design 
features and functional capabilities in accordance with the AIA rule 
and conducted an assessment reasonably formulated to identify design 
features and functional capabilities to show, with reduced use of 
operator action, that the facility can withstand the effects of an 
aircraft impact. In addition, the NRC determined that there will be no 
adverse impacts from complying with the requirements for consideration 
of aircraft impacts on conclusions reached by the NRC in its review of 
the original AP1000 design certification. The NRC's bases for approval 
of these changes are set forth in the FSER for the AP1000 amendment. As 
a result of these changes, the AP1000 design will achieve the 
Commission's objectives of enhanced public health and safety and 
enhanced common defense and security through improvement of the 
facility's inherent robustness to the impact of a large commercial 
aircraft at the design stage.
AP1000 Design Control Document Changes Since Revision 18
Introduction
    The NRC staff's (staff's) review of DCD Revision 18 (ADAMS 
Accession No. ML103260072) identified a few areas where the DCD wording 
should be revised for clarity, to resolve internal inconsistencies, or 
to provide updated versions of referenced technical reports. In 
addition, three technical issues were noted: a load combination for the 
shield building, the method used to evaluate tank sloshing, and 
containment peak pressure analysis error correction. As a result of 
these activities, Westinghouse submitted Revision 19 of the DCD on June 
13, 2011 (ADAMS Accession No. ML11171A315), and this is the version of 
the DCD that is being certified by this final rule. The NRC has 
determined that none of the changes from Revision 18 to Revision 19 of 
the DCD require an additional opportunity for public comment. These 
changes, which are organized into five subject areas, are discussed 
below.
    The NRC has also determined, in its review of Revision 19, that 
three of the five subject areas must be identified as Tier 2* matters 
in the Section VIII of the final rule. The NRC has determined that none 
of the three new Tier 2* designations in Section VIII.B.6 of the rule 
require an additional opportunity for public comment. The bases for the 
NRC's determinations are set forth below.
DCD Structural Design Information and Shield Building Tier 2* 
Information
    Revision 18 of the DCD moved some design details regarding 
structures, including the shield building, from supporting Westinghouse 
documents into the DCD itself. Some of the details were marked as Tier 
2*, based upon initial NRC staff comments. For example, information 
about penetrations was brought out of TR-9 into the DCD, and the shield 
building structural description was added to Section 3.8.4 in Revision 
18.
    The advanced final safety evaluation report (AFSER) included a 
confirmatory item to verify that the DCD appropriately reflected all 
necessary details regarding the structural design and shield building, 
and clearly showed which design details were to be Tier 2* (see AFSER 
Section 3.8.4 under ADAMS Accession No. ML103430502). The staff was 
able to close the confirmatory item after Westinghouse submitted 
Revision 19 of the DCD by verifying the appropriate structural details 
were in the DCD and the design details were identified as Tier 2*. 
These DCD revisions enhanced the description of the design and were not 
a result of changes to the design itself. Westinghouse report GLR-603, 
submitted on March 28, 2011 (ADAMS Accession No. ML110910541), was the 
nonproprietary version of the report that presented shield building 
information to be made Tier 2*, in addition to the DCD information 
separately added to Section 3.8 and Appendix 3H. The scope of the 
report was materials, connection details, and tie bar spacing.
    Use of steel composite modules was the heart of the revised shield 
building design, including the NRC's determination that existing 
consensus standards are not techinically applicable in all respects to 
the analysis for such modules. This was a key factor in the NRC 
conclusion that design details about the shield building are Tier 2* so

[[Page 82086]]

that any future changes to that information by the COL would receive 
prior staff review and approval. The staff considered the existing rule 
language as it relates to Tier 2* designation for structural 
information. For example, the existing rule includes use of ACI-349, 
definition of critical locations and thicknesses, nuclear island 
structural dimensions, and design summary of critical sections. Some of 
the critical sections are within the shield building, and ACI-349 was 
part of the design criteria. However, the staff concluded, during the 
course of final rule preparation, that the rule would be more clear if 
the use of steel composite module details that are designated in the 
DCD as Tier 2* was explicitly stated in the final rule (at Section 
VIII.B.6.c) and requested that Westinghouse designate this information 
at Tier 2* in Revision 19 of the DCD. Westinghouse included this change 
in Revision 19. As a result of the Tier 2* markings, a conforming 
change is being made to the final rule language to Section VIII.B.6.c 
about the categories of Tier 2* information that would expire at fuel 
load.
    The NRC does not believe that the DCD changes or the designation of 
this information as Tier 2* in the final rule require re-noticing. The 
material was publicly available in referenced reports, the staff's 
intention that the composite steel module design be designated Tier 2* 
was clear at the time of the public comment period, and there were no 
comments regarding the extent of Tier 2* inclusion in Revision 18.
Implementation of Revision 18 Commitments for the Shield Building
Load Combinations for Shield Building
    In the NRC staff's follow-up to an apparent editorial error in a 
table in the Westinghouse shield building report, the staff determined 
that Westinghouse had not documented in its calculations the numerical 
combination of the loads for external temperature conditions (minus 40 
degrees F) and a safe-shutdown earthquake (SSE). On April 12, 2011, the 
staff requested Westinghouse to document in the shield building report 
the numerical combination of loads for extreme ambient thermal loads 
and SSE loads, as specified in DCD Table 3.8.4-1 for steel structures 
and Table 3.8.4-2 for concrete structures. See meeting summary dated 
May 17, 2011 (ADAMS Accession No. ML111440298). By letter dated June 
15, 2011, Westinghouse responded to this request (ADAMS Accession No. 
ML111950098), and concluded that the current design is acceptable when 
the load combinations are explicitly analyzed. The analysis results are 
discussed in detail in Revision 4 of the shield building report. 
Changes were made to the DCD to reflect the results of this load 
combination analysis, but the changes did not involve any changes to 
the methodology or the design of the shield building. The specific DCD 
changes were the addition of Section 3.8.4.5.5 to discuss the load 
combination analysis, and updating of tables of results in Appendix 3H. 
No change to the language of the AP1000 DCR in 10 CFR part 52, Appendix 
D was made as a result of the DCD changes.
    The NRC does not believe these DCD changes require re-noticing 
because Revision 18 of the DCD stated that the design would be verified 
using the required load combinations, and these load combinations had 
previously been approved by the NRC for use in AP1000 analyses similar 
to those for the shield building elements requiring reanalysis. There 
was no change to the methodology or the actual design of the shield 
building was needed, and there was no change to the language of the 
AP1000 DCR. The also NRC notes that the June 16, 2011 ``petition'' 
(filed by John Runkle) that requested the NRC terminate the rulemaking 
specifically raised the three technical issues in Revision 19, 
including the load combination topic.
Passive Containment Cooling Water Storage Tank
    During the analysis of the thermal plus earthquake load combination 
for the passive containment cooling water storage tank (located on top 
of the shield building), Westinghouse determined that it had not 
performed an analysis of hydrodynamic loads using an equivalent static 
analysis as stated in Westinghouse's response (ADAMS Accession No. 
ML102650098) to an action item from the NRC's shield building report 
review (documented in AFSER Chapter 3, ADAMS Accession No. 
ML103430502). Instead, the analysis had been done by response spectrum 
analysis. Both the equivalent static method and the response spectrum 
method had previously been approved by the NRC for use in the AP1000 
design for structural analyses as described in Revision 18 of the DCD. 
This issue was discussed in a May 17, 2011, public meeting (see meeting 
summary dated May 26, 2011 (ADAMS Accession No. ML111430775)). In 
response, Westinghouse performed the analysis with the equivalent 
static method and presented the results in the revised shield building 
report and in DCD Revision 19 as follows. The use of the equivalent 
static method for the tank is discussed in Section 3.7 and Appendix 3G, 
and a table and figure were added to Appendix 3H. The revised shield 
building report included the results of the load combination for the 
containment cooling water storage tank using the equivalent static 
analytical method, which demonstrated that the design remained adequate 
when evaluated using the equivalent static analytical method. No change 
to the language of the AP1000 DCR in 10 CFR Part 52, Appendix D was 
made as a result of the DCD changes.
    The NRC does not believe these DCD changes require renoticing. 
Revision 18 of the DCD stated that the design would be verified through 
the use of the equivalent static method, and that method had been 
previously approved by the NRC for AP1000 analyses equivalent to that 
peformed for the containment cooling water tank. No change to the 
actual design of the tank was needed, and there was no change to the 
language of the AP1000 DCR. The NRC also notes that one of the 
petitions (dated June 16, 2011) that the NRC is responding to in the 
comment response document specifically raised this issue and the NRC 
has provided an answer similar to that described above.
Debris Limits
    In its December 20, 2010, letter on long-term core cooling (ADAMS 
Accession No. ML103410348), the ACRS concluded that the regulatory 
requirements for long-term core cooling for design-basis accidents have 
been adequately met, based on cleanliness requirements specified in the 
amendment. In particular, the amount of latent debris that might be 
present in the containment is an important parameter. The ACRS further 
stated that any future proposed relaxation of the cleanliness 
requirements will require substantial additional data and analysis. In 
their January 24, 2011, (ADAMS Accession No. ML110170006) report on the 
Vogtle COL application, which references the AP1000 design, the ACRS 
recommended that the containment interior cleanliness limits on latent 
debris should be included in the Technical Specifications (TSs) for the 
Vogtle plant.
    In a letter dated February 23, 2011 (ADAMS Accession No. 
ML110590455), Westinghouse proposed DCD markups to designate 
information in Section 6.3 including debris sources such as latent 
debris (and the amount of fiber) as Tier 2*. Revision 19 of the DCD 
includes changes to mark selected information as Tier 2*.

[[Page 82087]]

    The NRC made a conforming change to the final rule language to 
provide a new item as Section VIII.B.6.b(7), ``Screen design 
criteria,'' for this new type of Tier 2* information. The NRC believes 
that inclusion of debris limits in the AP1000 DCD as Tier 2* 
information, rather than including such limits in each plant 
referencing the AP1000, represents a better regulatory approach for 
achieving the intent of the ACRS. Inclusion of debris limits in the 
AP1000 and its designation as Tier 2* would ensure that there is 
consistency across all referencing plants with repect to debris 
control, and ensures NRC regulatory control of any future relaxations 
of the limits, as discussed in the staff's March 3, 2011, response to 
the ACRS (ADAMS Accession No. ML110350198).
    The NRC does not believe that this change to the DCD marking or to 
the final rule language requires renoticing because the ACRS letter, 
the staff response, and the Westinghouse letter, were all publicly 
available during the comment period, and the public had a fair 
opportunity to comment on this matter. In this regard, the staff notes 
that the April 6, 2011, ``petition'' (filed by John Runkle) that 
requested the NRC to suspend the AP1000 amendment rulemaking, included 
discussion about this topic with specific reference to the ACRS letter 
(ADAMS Accession No. ML11108A077). Numerous other comment submissions 
pointed to this petition as part of their comments. This lends support 
to the NRC's view that the public had adequate notice and an 
opportunity to comment on this matter. In addition, the inclusion of 
debris limits as Tier 2* represents a new limitation, not present in 
the prior revisions of the AP1000 DCD, which will require a referencing 
COL holder to use debris limits as specified in the AP1000 DCD. Given 
that the designation of the debris limits as Tier 2* represents a new 
restriction agreed to by Westinghouse, a matter on which the NRC 
received public comment, the staff does not believe that an additional 
opportunity for public comment need be provided on the inclusion of 
debris limits in Revision 19 of the DCD and the designation of those 
limits as Tier 2*.
Heat Sinks and Containment Pressure Analysis
    In its December 13, 2010, letter on the AP1000 design 
certification, the ACRS identified an error in the previously certified 
Revision 15 of the DCD (ADAMS Accession No. ML103410351) concerning the 
containment cooling analysis. The error affected the time at which 
steady-state film coverage is achieved on the exterior of the 
containment vessel. In a February 5, 2011, letter, the NRC staff agreed 
with the ACRS, and indicated that Westinghouse agreed that the error 
existed and should be corrected. The letter also indicated that the NRC 
staff would monitor Westinghouse's corrective actions and review any 
needed revisions to the DCD (ADAMS Accession No. ML103560411).
    In the course of correcting the steady-state film coverage error, 
after the proposed rule was published, Westinghouse identified other 
errors and modeling updates in supporting analyses that affected the 
calculated post-accident peak containment pressure (the highest peak 
pressure in the event of a large break loss-of-coolant accident). The 
net impact of correcting the steady-state film error and the subsequent 
Westinghouse-identified errors and modeling updates was an increase in 
calculated peak containment pressure from 57.8 psig to 59.2 psig, which 
would have exceeded the 59 psig post-accident peak containment pressure 
acceptance criterion in the existing AP1000 DCR.
    Therefore, as part of the revised analysis to account for all the 
identified errors, Westinghouse relied upon a limited number of 
existing structural elements (gratings) within the containment as heat 
sinks, in order to remain within the 59 psig post-accident peak 
containment pressure acceptance criterion. Westinghouse's revised 
analysis used the NRC-approved methodology in the existing AP1000 DCR 
containment pressure calculation, and the method for crediting heat 
sink capacity as described in Westinghouse documents WCAP-15846 
(proprietary) and WCAP-15862 (nonproprietary) ``WGOTHIC Application to 
AP600 and AP1000,'' Revision 1, March 2004, which are incorporated by 
reference in the previously certified Revision 15 of the DCD. In 
addition, the Westinghouse-revised analysis used the NRC-approved 59 
psig post-accident peak containment pressure acceptance criterion in 
the existing AP1000 DCD, Revision 15.
    The staff safety evaluation of the Westinghouse revised analysis is 
included in Sections 23.X and 23.Y of the FSER (ADAMS Accession No. 
ML112061231). Table 6.2.1.1-10 of Revision 19 of the DCD includes the 
credited elements. The ACRS reviewed the Westinghouse corrections, and 
agreed that Westinghouse's revised analysis continues to demonstrate 
that the containment will be able to withstand the post-accident peak 
containment pressure (ADAMS Accession No. ML11256A180), and that the 
reevaluated pressure is based on a sufficiently conservative 
methodology. The final AP1000 rule language designates this ``heat sink 
data for containment analysis'' by adding it as a new Tier 2* item in 
Section VIII.B.6.b(8). The NRC decided to control any future changes to 
the credited elements by designating the material as Tier 2* because 
the geometry and location of the heat sinks could impact their 
effectiveness.
    The NRC does not believe that the revisions to Table 6.2.1.1-10 of 
Revision 19 of the DCD require renoticing for several reasons. The 
gratings to be credited as heat sinks were already part of the approved 
AP1000 design and were not part of the proposed amendment to the AP1000 
DCR described design. Thus, the actual DCD did not involve any new 
design elements being added. The use of heat sinks as part of the 
containment pressure calculation and the method for crediting heat sink 
capacity were described in the DCD Revision 15. The criterion for 
evaluating the acceptability of the change continues to be the 
calculated post-accident peak containment pressure of 59 psig. 
Therefore, the revised Westinghouse analysis did not involve the use of 
any previously unapproved design methodologies or acceptance criteria; 
the methodology used and the acceptance criterion (59 psig post-
accident peak containment pressure) is in the already-approved AP1000 
DCR. Finally, crediting of the gratings as heat sinks in the revised 
analysis did not introduce any new safety issues not previously 
addressed. Therefore, the NRC does not believe that opportunity for 
public comment need be provided on the rule language change.
    The NRC does not believe that the designation of the heat sink as 
Tier 2* requires renoticing. As discussed above, the Tier 2* change is 
a direct result of the Westinghouse revised analysis that does not 
warrant an additional opportunity for public comment. The designation 
of this information as Tier 2* adds a new limitation, not present in 
the prior revisions of the AP1000 DCD, which limits a referencing 
combined license applicant/holder to alter the heat sink information 
for the grating and all other heat sinks credited in the containment 
peak pressure analysis. Given that the designation o