[Federal Register Volume 69, Number 194 (Thursday, October 7, 2004)]
[Notices]
[Pages 60193-60196]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-22546]


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NUCLEAR REGULATORY COMMISSION


Proposed Generic Communication; Steam Generator Tube Integrity 
and Associated Technical Specifications

AGENCY: Nuclear Regulatory Commission.

ACTION: Notice of opportunity for public comment.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is proposing to 
issue a generic letter (GL) to request that addressees submit a 
description of their program for ensuring steam generator (SG) tube 
integrity for the interval between inspections and description of the 
methodology used to assess the effects of non-pressure-related loads 
such as bending on SG tube integrity. Addressees should also provide a 
safety assessment demonstrating that the SG tubes will have adequate 
structural and leakage integrity (with appropriate regulatory margins) 
at the time of their next SG tube inspection, taking into account the 
effects of non-pressure-related loads.
    This Federal Register notice is available through the NRC's 
Agencywide Documents Access and Management System (ADAMS) under 
accession number ML042710075.

DATES: Comment period expires December 6, 2004. Comments submitted 
after this date will be considered if it is practical to do so, but 
assurance of consideration cannot be given except for comments received 
on or before this date.

ADDRESSEES: Submit written comments to the Chief, Rules and Directives 
Branch, Division of Administrative Services, Office of Administration, 
U.S. Nuclear Regulatory Commission, Mail Stop T6-D59, Washington, DC 
20555-0001, and cite the publication date and page number of this 
Federal Register notice. Written comments may also be delivered to NRC 
Headquarters, 11545 Rockville Pike (Room T-6D59), Rockville, Maryland, 
between 7:30 am and 4:15 pm on Federal workdays.

FOR FURTHER INFORMATION CONTACT: Kenneth Karwoski, NRR at 301-415-2752 
or by e-mail at <a href="/cdn-cgi/l/email-protection#1f7475742e5f716d7c31787069"><span class="__cf_email__" data-cfemail="264d4c4d176648544508414950">[email protected]</span></a> or Maitri Banerjee, NRR at 301-415-2277 or 
by e-mail at <a href="/cdn-cgi/l/email-protection#f29f8a90b29c8091dc959d84"><span class="__cf_email__" data-cfemail="b3decbd1f3ddc1d09dd4dcc5">[email protected]</span></a>.

SUPPLEMENTARY INFORMATION:

Draft NRC Generic Letter 2004-XX: Steam Generator Tube Integrity and 
Associated Technical Specifications

Addressees

    All holders of operating licenses for pressurized-water reactors 
(PWRs), except those who have permanently ceased operations and have 
certified that fuel has been permanently removed from the reactor 
vessel and {the following plants that have already modified their 
technical specifications to be consistent with those in the 
Attachment{time} .

Purpose

    The U.S. Nuclear Regulatory Commission (NRC) is issuing this 
generic letter (GL) to:
    (1) Request that addressees submit a description of their program 
for ensuring steam generator (SG) tube integrity for the interval 
between inspections; and
    (2) Request that addressees submit a description of the methodology 
used to assess the effects of non-pressure-related loads such as 
bending on SG tube integrity. Addressees should also provide a safety 
assessment demonstrating that the SG tubes will have adequate 
structural and leakage integrity (with appropriate regulatory margins) 
at the time of their next SG tube inspection, taking into account the 
effects of non-pressure-related loads.

Discussion

    Steam generator tubes function as an integral part of the reactor 
coolant pressure boundary (RCPB) and also serve to isolate radiological 
fission products in the primary coolant from the secondary coolant and 
the environment. For the purposes of this generic letter, tube 
integrity means that the tubes are capable of performing these 
functions in accordance with the plant design and licensing basis, 
including applicable regulatory requirements.
    During operation, licensees are required to monitor and maintain 
the condition of the SG tubing with the objective of ensuring its 
continued integrity. Specifically, licensees are required by 10 CFR 
50.55a(b)(2)(iii), 10 CFR 50.55a(g), or by the plant technical 
specifications to perform periodic inservice inspections and to repair 
(e.g., sleeve) or remove from service (by installing plugs in the tube 
ends) all tubes found to contain flaws exceeding

[[Page 60194]]

the plugging limit (i.e., tube repair criteria).
    The current technical specification requirements for inspection and 
repair of SG tubing were developed in the 1970s and define a 
prescriptive approach for ensuring tube integrity. This prescriptive 
approach involves inspecting the tubing at specified intervals, 
implementing specified tube inspection sampling plans, and repairing or 
removing from service by plugging all tubes found by inspection to 
contain flaws in excess of specified flaw repair criteria. However, as 
evidenced by operating experience, the prescriptive approach defined in 
the technical specifications may not be sufficient to ensure that tube 
integrity is maintained. For example, in cases of low to moderate 
levels of degradation, the technical specifications only require that 
3-to 21-percent of the tubes be inspected, irrespective of whether the 
inspection results indicate that additional tubes need to be inspected 
to reasonably ensure that tubes with flaws that may exceed the tube 
repair criteria or which may impair tube integrity are detected. In 
addition, the technical specifications (and Section XI of the American 
Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code) 
do not explicitly address the inspection methods to be employed for 
different tube degradation mechanisms at specific tube locations, nor 
are the specific objectives to be fulfilled by the selected methods 
explicitly defined. Also, incremental flaw growth between inspections 
can in many instances exceed what is allowed for in the specified tube 
repair criteria. In such cases, the specified inspection frequencies 
may not ensure reinspection of a tube before its integrity is impaired. 
In short, current technical specification surveillance requirements may 
not require licensees to actively manage their SG programs so as to 
provide reasonable assurance that tube integrity is maintained. As a 
result of the above, licensees have frequently found it necessary to 
implement measures beyond the technical specification requirements to 
ensure adequate tube integrity. These measures are frequently 
accompanied by interaction with the NRC staff in an oversight or review 
capacity to ensure that adequate tube integrity is being maintained.
    The NRC staff, with external stakeholder involvement, embarked on 
efforts to improve the SG tube integrity regulatory framework as 
discussed in SECY-03-0800, ``Steam Generator Tube Integrity (SGTI)--
Plans for Revising the Associated Regulatory Framework.'' As a result 
of these efforts, the NRC and industry generically developed modified 
technical specifications for addressing steam generator tube integrity. 
These generically developed technical specifications were recently 
incorporated into one facility's technical specifications. (Proposals 
to change the plant-specific technical specifications are reviewed in 
accordance with the license amendment review process to confirm their 
acceptability). These modified technical specifications are attached to 
this generic letter for your information. The approach taken in the 
modified technical specifications in the Attachment is conceptually 
similar to the approach outlined in the industry initiative referred to 
as NEI 97-06, ``Steam Generator Program Guidelines.'' The modified 
technical specifications in the Attachment are performance-based in 
that they are focused on ensuring that the tubing satisfies performance 
criteria that are commensurate with tube integrity. This approach can 
be readily adapted to new or unexpected degradation mechanisms and 
advances in nondestructive examination technology. This approach also 
includes programmatic elements to ensure that tubes are being 
adequately monitored and maintained relative to the performance 
criteria.
    The requirements pertaining to the integrity of the SG tubes are 
contained within Title 10 of the Code of Federal Regulations (10 CFR). 
Specifically, the general design criteria (GDC) \1\ described in 
Appendix A to 10 CFR part 50 contain, in part, requirements related to 
the RCPB (e.g., GDC 14, GDC 30, GDC 32). In addition to the GDC, 10 CFR 
50.55a specifies that components that are part of the RCPB must meet 
the requirements for Class 1 components in Section III and XI of the 
American Society of Mechanical Engineers (ASME) Boiler and Pressure 
Vessel Code unless the plant technical specifications for surveillance 
differ from those specified in the ASME Code, in which case the 
technical specifications govern.
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    \1\ Or, for PWR facilities licensed before the issuance of 10 
CFR part 50, Appendix A, similar requirements in the plant-specific 
principal design criteria.
---------------------------------------------------------------------------

    The requirements pertaining to the content of a plant's technical 
specifications are given in 10 CFR 50.36, ``Technical Specifications.'' 
All currently operating PWR licensees have technical specifications 
governing the surveillance of the SG tubes. These technical 
specifications also include operational leakage limits so that if 
significant leakage develops, the plant is shut down. The plugging 
limits in the technical specifications were developed to ensure that 
degraded tubes: (1) Maintain factors of safety against gross rupture 
consistent with the plant design basis (i.e., consistent with the 
stress limits of the ASME Code, Section III); and (2) maintain leakage 
integrity consistent with the plant licensing basis while, at the same 
time, allowing for potential flaw size measurement error and flaw 
growth between inservice inspections.
    As part of the plant licensing basis, applicants for PWR licenses 
are also required to analyze the consequences of postulated design-
basis accidents. Typical accidents analyzed are the SG tube rupture, 
the locked-rotor, control rod ejection, and a main steamline break. 
These analyses consider the potential primary-to-secondary leakage 
through the tubes during these events and must show that the offsite 
radiological doses do not exceed 10 CFR part 100 limits (or some 
fraction thereof) and GDC 19 of Appendix A to 10 CFR part 50.
    Irrespective of technical specification requirements for SG tube 
inspection and repair, licensees are also required by 10 CFR part 50, 
Appendix B Criterion XVI, ``Corrective Action,'' to ensure that 
conditions adverse to quality are promptly identified and corrected. In 
the case of significant conditions adverse to quality, the measures 
shall assure that the cause of the condition is determined and 
corrective action taken to preclude repetition.
    The staff is requesting information as to: (1) Actions licensees 
are taking or will take to ensure tube integrity is being maintained, 
and (2) contemplated changes to the technical specifications to reflect 
these actions.
    As discussed above, the approach in the attached technical 
specifications is performance-based. There are three performance 
criteria for the SG tubes: (1) A structural integrity performance 
criterion, (2) a primary-to-secondary leakage performance criterion for 
normal operation, and (3) a primary-to-secondary leakage performance 
criterion for postulated accident conditions.
    During public interactions with stakeholders on the structural 
integrity performance criterion, the staff became aware that the 
effects of various non-pressure-related loads such as bending loads may 
not be fully addressed in industry guidance documents for assessing the 
integrity of degraded SG tubes. Non-pressure-related loads were 
assessed in the original design of the SG tubes so as to ensure that 
nondegraded tubes would have adequate integrity for the full range of 
operating conditions. As a result, this generic letter requests 
addressees to discuss how they have

[[Page 60195]]

assessed the effects of non-pressure-related loads in their assessments 
of tube integrity and to discuss whether all tubes will have adequate 
structural integrity at the time of their next SG tube inspection, 
taking all loading conditions on the tube into account.

Requested Information

    Addressees are requested to provide the following information to 
the NRC within 60 days of the date of this generic letter:
    1. A description of the actions they are taking or will take to 
ensure tube integrity is being maintained and contemplated changes to 
the technical specifications to reflect these actions.
    2. A description of the methodology used to assess the effects of 
non-pressure-related loads such as bending on SG tube integrity. In 
addition, addressees should provide a safety assessment demonstrating 
that the SG tubes will have adequate structural and leakage integrity 
at the time of their next SG tube inspection, taking into account the 
effects of non-pressure-related loads.

Required Response

    In accordance with 10 CFR 50.54(f), addressees are required to 
submit written responses to this generic letter. Two options are 
available:
    (a) Addressees may choose to submit written responses providing the 
information requested above within the requested time period.
    (b) Addressees who cannot meet the requested completion date or who 
choose an alternate course of action are required to so notify the NRC 
in writing as soon as possible but no later than 30 days from the date 
of this generic letter. The response must address any alternative 
course of action proposed, including the basis for the acceptability of 
the proposed alternative course of action, and the basis for finding 
that the SGs remain operable. If the information requested in the 
previous section of this GL will be subsequently provided, the response 
must set forth the schedule for submitting the information.
    The required written response should be addressed to the U.S. 
Nuclear Regulatory Commission, ATTN: Document Control Desk, 11555 
Rockville Pike, Rockville, Maryland 20852, under oath or affirmation 
under the provisions of section 182a of the Atomic Energy Act of 1954, 
as amended, and 10 CFR 50.54(f). In addition, a copy of the response 
should be sent to the appropriate regional administrator.

Reasons for Requested Information

    This GL requests addressees to submit information. The requested 
information will enable the NRC staff to determine whether addressees' 
SG tube integrity programs provide reasonable assurance of tube 
integrity consistent with their design and licensing basis and 
applicable regulatory requirements (10 CFR part 50, Appendix 
A<SUP>1</SUP>; 10 CFR part 50, Appendix B). In addition, the requested 
information will enable the NRC staff to determine whether SG tube 
integrity is being maintained under all loading conditions consistent 
with the design and licensing basis and applicable regulatory 
requirements (10 CFR part 50, Appendix A<SUP>1</SUP>).
    The NRC staff will review the responses to this GL in order to 
determine whether additional actions are necessary.

Backfit Discussion

    Under the provisions of section 182a of the Atomic Energy Act of 
1954, as amended, and 10 CFR 50.54(f), this GL transmits an information 
request for the purpose of verifying compliance with applicable 
existing requirements. Specifically, the requested information will 
enable the NRC staff to determine whether the applicable requirements 
discussed above are being met. No backfit is either intended or 
approved in the context of issuance of this GL. Therefore, the staff 
has not performed a backfit analysis.

Federal Register Notification

    To be done after the public comment period.

Small Business Regulatory Enforcement Fairness Act

    The NRC has determined that this action is not subject to the Small 
Business Regulatory Enforcement Fairness Act of 1996.

Paperwork Reduction Act Statement

    This GL contains information collection requirements that are 
subject to the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et 
seq.). These information collections were approved by the Office of 
Management and Budget, approval no. 3150-0011, which expires on 
February 28, 2007.
    The burden of these mandatory information collections on the public 
is estimated to average 200 hours per response, including the time for 
reviewing instructions, searching existing data sources, gathering and 
maintaining the data needed, and completing and reviewing the 
information collection. Send comments regarding this burden estimate or 
any other aspect of these information collections, including 
suggestions for reducing the burden, to the Records and FOIA/Privacy 
Services Branch (T-5 F52), U.S. Nuclear Regulatory Commission, 
Washington, DC 20555-0001, or by Internet electronic mail to 
<a href="/cdn-cgi/l/email-protection#9ef7f0f8f1fdf1f2f2fbfdeaeddef0ecfdb0f9f1e8"><span class="__cf_email__" data-cfemail="ea83848c85898586868f899e99aa849889c48d859c">[email protected]</span></a>; and to the Desk Officer, Office of Information 
and Regulatory Affairs, NEOB-10202, (3150-0011), Office of Management 
and Budget, Washington, DC 20503.

Public Protection Notification

    The NRC may not conduct or sponsor, and a person is not required to 
respond to, a request for information or an information collection 
requirement unless the requesting document displays a currently valid 
OMB control number.

Sample Technical Specifications

Steam Generator (SG) Program

    A SG Program shall be established and implemented to ensure that SG 
tube integrity is maintained. The SG Program shall include the 
following provisions:
    a. Provisions for condition-monitoring assessments. A condition-
monitoring assessment is an evaluation of the ``as-found'' condition of 
the tubing with respect to the performance criteria for structural 
integrity and accident-induced leakage. The ``as-found'' condition 
refers to the condition of the tubing during a SG inspection outage, as 
determined from the inservice inspection results or by other means, 
prior to the plugging of tubes. Condition-monitoring assessments shall 
be conducted during each outage during which the SG tubes are inspected 
or plugged to confirm that the performance criteria are being met.
    b. Performance criteria for SG tube integrity. SG tube integrity 
shall be maintained by meeting the performance criteria for tube 
structural integrity, accident-induced leakage, and operational 
LEAKAGE.
    1. Structural integrity performance criterion: All inservice SG 
tubes shall retain structural integrity over the full range of normal 
operating conditions (including startup, operation in the power range, 
hot standby, and cooldown and all anticipated transients included in 
the design specifications) and design-basis accidents. This includes 
retaining a safety factor of 3.0 against burst under the normal steady 
state full-power operation primary-to-secondary pressure differential 
and a safety factor of 1.4 against burst applied to the design-basis 
accident primary-to-secondary pressure differentials. Apart from the 
above requirements, additional loading conditions associated with the 
design-basis accidents, or combination of accidents in accordance with 
the

[[Page 60196]]

design and licensing basis, shall also be evaluated to determine if the 
associated loads contribute significantly to burst or collapse. In the 
assessment of tube integrity, those loads that do significantly affect 
burst or collapse shall be determined and assessed in combination with 
the loads due to pressure with a safety factor of 1.2 on the combined 
primary loads and 1.0 on axial secondary loads.
    2. Accident-induced leakage performance criterion: The primary-to-
secondary accident-induced leakage rate for any design-basis accident, 
other than a SG tube rupture, shall not exceed the rates assumed in the 
accident analysis for total leakage rate from all SGs and leakage rate 
from an individual SG. Accident-induced leakage is not to exceed 
[licensee to insert value] gallons per day through each SG and 
[licensee to insert value] gallons per day through all SGs.
    3. The operational LEAKAGE performance criterion is specified in 
limiting condition for operation (LCO) [licensee to insert reference to 
appropriate LCO. For limits currently greater than 150 gallons per day, 
the LCO limit should be lowered to a value less than or equal to 150 
gallons per day.]
    c. SG tube repair criteria. Tubes found by inservice inspection to 
contain flaws with a depth equal to or exceeding 40 percent of the 
nominal tube wall thickness shall be plugged.
    d. Provisions for SG tube inspections. Periodic SG tube inspections 
shall be performed. The number and portions of the tubes inspected and 
the method of inspection shall be performed with the objective of 
detecting flaws of any type (for example, volumetric flaws, axial and 
circumferential cracks) that may be present along the length of the 
tube, from the tube-to-tubesheet weld at the tube inlet to the tube-to-
tubesheet weld at the tube outlet, and that may satisfy the applicable 
tube repair criteria. The tube-to-tubesheet weld is not part of the 
tube. In addition to meeting requirements d.1, d.2, and d.3 below, the 
inspection scope, inspection methods, and inspection intervals shall be 
such as to ensure that SG tube integrity is maintained until the next 
SG inspection. An assessment of degradation shall be performed to 
determine the type and location of flaws to which the tubes may be 
susceptible and, based on this assessment, to determine which 
inspection methods need to be employed and at what locations.
    1. Inspect 100 percent of the tubes in each SG during the first 
refueling outage following SG replacement.
    2. Inspect 100 percent of the tubes at sequential periods of [for 
licensees with thermally treated Alloy 690 tubes, insert ``144, 108, 
72, and thereafter 60 effective full-power months;'' for licensees with 
thermally treated Alloy 600 tubes, insert ``120, 90, and thereafter 60 
effective full-power months;'' for licensees with mill-annealed Alloy 
600 tubes, insert ``60 effective full-power months;'']. The first 
sequential period shall be considered to begin after the first 
inservice inspection of the SGs. In addition, inspect 50 percent of the 
tubes by the refueling outage nearest the midpoint of the period and 
the remaining 50 percent by the refueling outage nearest the end of the 
period. No SG shall operate for more than [for licensees with thermally 
treated Alloy 690 tubes, insert ``72 effective full-power months or 
three refueling outages;'' for licensees with thermally treated Alloy 
600 tubes, insert ``48 effective full-power months or two refueling 
outages;'' for licensees with mill-annealed Alloy 600 tubes, insert 
``24 effective full-power months or each refueling outage'' (whichever 
is less)] without being inspected.
    3. If crack indications are found in any SG tube, then the next 
inspection for each SG for the degradation mechanism that caused the 
crack indication shall not exceed 24 effective full-power months or one 
refueling outage (whichever is less). If definitive information, such 
as from examination of a pulled tube, diagnostic nondestructive 
testing, or an engineering evaluation indicates that a cracklike 
indication is not associated with a crack or cracks, then the 
indication need not be treated as a crack.
    e. Provisions for monitoring operational primary-to-secondary 
leakage.

Steam Generator (SG) Tube Inspection Report

    A report shall be submitted within 180 days of the initial entry 
into MODE 4 following completion of the inspection. The report shall 
include:
    a. The scope of inspection performed on each SG.
    b. Active degradation mechanisms found.
    c. Nondestructive examination techniques utilized for each 
degradation mechanism.
    d. Location, orientation (if linear), and measured sizes (if 
available) of service-induced indications.
    e. Number of tubes plugged during the inspection outage for each 
active degradation mechanism.
    f. Total number and percentage of tubes plugged to date.
    g. The results of condition monitoring, including the results of 
tube pulls and in-situ testing.

End

    Documents may be examined, and/or copied for a fee, at the NRC's 
Public Document Room at One White Flint North, 11555 Rockville Pike 
(first floor), Rockville, Maryland. Publicly available records will be 
accessible electronically from the Agencywide Documents Access and 
Management System (ADAMS) Public Electronic Reading Room on the 
Internet at the NRC Web site, http://www.nrc.gov/NRC/ADAMS/index.html. 
If you do not have access to ADAMS or if you have problems in accessing 
the documents in ADAMS, contact the NRC Public Document Room (PDR) 
reference staff at 1-800-397-4209 or 301-415-4737 or by e-mail to 
<a href="/cdn-cgi/l/email-protection#62120610220c10014c050d14"><span class="__cf_email__" data-cfemail="53233721133d21307d343c25">[email protected]</span></a>.

    Dated in Rockville, Maryland, this 30 day of September, 2004.

    For the Nuclear Regulatory Commission.
Francis M. Costello,
Acting Branch Chief, Reactor Operations Branch, Division of Inspection 
Program Management, Office of Nuclear Reactor Regulation.
[FR Doc. 04-22546 Filed 10-6-04; 8:45 am]
BILLING CODE 7590-01-P


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