Proposed License Renewal Interim Staff Guidance LR-ISG-2006-01: Plant-Specific Aging Management Program for Inaccessible Areas of Boiling Water Reactor Mark I Steel Containment Drywell Shell Solicitation of Public Comment, 27010-27012 [E6-7000]

Download as PDF 27010 Federal Register / Vol. 71, No. 89 / Tuesday, May 9, 2006 / Notices mstockstill on PROD1PC68 with NOTICES statement of the alleged facts or expert opinion which support the contention and on which the petitioner intends to rely in proving the contention at the hearing. The petitioner must also provide references to those specific sources and documents of which the petitioner is aware and on which the petitioner intends to rely to establish those facts or expert opinion. The petition must include sufficient information to show that a genuine dispute exists with the applicant on a material issue of law or fact.1 Contentions shall be limited to matters within the scope of the amendment under consideration. The contention must be one which, if proven, would entitle the petitioner to relief. A petitioner/requestor who fails to satisfy these requirements with respect to at least one contention will not be permitted to participate as a party. Each contention shall be given a separate numeric or alpha designation within one of the following groups: 1. Technical—primarily concerns/ issues relating to technical and/or health and safety matters discussed or referenced in the applications. 2. Environmental—primarily concerns/issues relating to matters discussed or referenced in the environmental analysis for the applications. 3. Miscellaneous—does not fall into one of the categories outlined above. As specified in 10 CFR 2.309, if two or more petitioners/requestors seek to co-sponsor a contention, the petitioners/ requestors shall jointly designate a representative who shall have the authority to act for the petitioners/ requestors with respect to that contention. If a petitioner/requestor seeks to adopt the contention of another sponsoring petitioner/requestor, the petitioner/requestor who seeks to adopt the contention must either agree that the sponsoring petitioner/requestor shall act as the representative with respect to that contention, or jointly designate with the sponsoring petitioner/requestor a representative who shall have the authority to act for the petitioners/ requestors with respect to that contention. Those permitted to intervene become parties to the proceeding, subject to any limitations in the order granting leave to intervene, and have the opportunity to participate fully in the conduct of the 1 To the extent that the applications contain attachments and supporting documents that are not publicly available because they are asserted to contain safeguards or proprietary information, petitioners desiring access to this information should contact the applicant or applicant’s counsel and discuss the need for a protective order. VerDate Aug<31>2005 15:42 May 08, 2006 Jkt 208001 hearing. Since the Commission has made a final determination that the amendment involves no significant hazards consideration, if a hearing is requested, it will not stay the effectiveness of the amendment. Any hearing held would take place while the amendment is in effect. A request for a hearing or a petition for leave to intervene must be filed by: (1) First class mail addressed to the Office of the Secretary of the Commission, U.S. Nuclear Regulatory Commission, Washington, DC 20555– 0001, Attention: Rulemaking and Adjudications Staff; (2) courier, express mail, and expedited delivery services: Office of the Secretary, Sixteenth Floor, One White Flint North, 11555 Rockville Pike, Rockville, Maryland 20852, Attention: Rulemaking and Adjudications Staff; (3) E-mail addressed to the Office of the Secretary, U.S. Nuclear Regulatory Commission, HearingDocket@nrc.gov; or (4) facsimile transmission addressed to the Office of the Secretary, U.S. Nuclear Regulatory Commission, Washington, DC, Attention: Rulemakings and Adjudications Staff at (301) 415–1101, verification number is (301) 415–1966. A copy of the request for hearing and petition for leave to intervene should also be sent to the Office of the General Counsel, U.S. Nuclear Regulatory Commission, Washington, DC 20555– 0001, and it is requested that copies be transmitted either by means of facsimile transmission to (301) 415–3725 or by email to OGCMailCenter@nrc.gov. A copy of the request for hearing and petition for leave to intervene should also be sent to the attorney for the licensee. Nontimely requests and/or petitions and contentions will not be entertained absent a determination by the Commission or the presiding officer or the Atomic Safety and Licensing Board that the petition, request and/or the contentions should be granted based on a balancing of the factors specified in 10 CFR 2.309(a)(1)(i)–(viii). Indiana Michigan Power Company, Docket No. 50–316, Donald C. Cook Nuclear Plant, Unit 2 (DCCNP–2), Berrien County, Michigan Date of amendment request: April 10, 2006, as supplemented on April 12, and 13 (two letters), 2006. Description of amendment request: The amendment revised Surveillance Requirement 3.8.1.11 of the DCCNP–2 Technical Specifications, raising the diesel generator load rejection voltage test limit from 5000 volts to 5350 volts. Date of issuance: April 13, 2006. Effective date: April 13, 2006. Amendment No.: 276. PO 00000 Frm 00091 Fmt 4703 Sfmt 4703 Facility Operating License No. DPR– 74: Amendment revises the Technical Specifications. Public comments requested as to proposed no significant hazards consideration (NSHC): No. The Commission’s related evaluation of the amendment, finding of emergency circumstances, state consultation, and final NSHC determination are contained in a safety evaluation dated April 13, 2006. Attorney for licensee: James M. Petro, Jr., Esquire, One Cook Place, Bridgman, MI 49106. NRC Branch Chief: L. Raghavan. Dated at Rockville, Maryland, this 1st day of May 2006. For the Nuclear Regulatory Commission. Catherine Haney, Director, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation. [FR Doc. 06–4243 Filed 5–8–06; 8:45 am] BILLING CODE 7590–01–P NUCLEAR REGULATORY COMMISSION Proposed License Renewal Interim Staff Guidance LR–ISG–2006–01: Plant-Specific Aging Management Program for Inaccessible Areas of Boiling Water Reactor Mark I Steel Containment Drywell Shell Solicitation of Public Comment Nuclear Regulatory Commission. ACTION: Solicitation of public comment. AGENCY: SUMMARY: The Nuclear Regulatory Commission (NRC) is soliciting public comment on its Proposed License Renewal Interim Staff Guidance LR– ISG–2006–01. This LR–ISG proposes that applicants for license renewal for a plant with a boiling water reactor Mark I steel containment provide a plantspecific aging management program that addresses the potential loss of material due to corrosion in the inaccessible areas of their Mark I steel containment drywell shell for the period of extended operation. The NRC staff issues LR–ISGs to facilitate timely implementation of the license renewal rule and to review activities associated with a license renewal application (LRA). Upon receiving public comments, the NRC staff will evaluate the comments and make a determination to incorporate the comments, as appropriate. Once the NRC staff completes the LR–ISG, it will issue the LR–ISG for NRC and industry use. The NRC staff will also incorporate the approved LR–ISG into the next E:\FR\FM\09MYN1.SGM 09MYN1 mstockstill on PROD1PC68 with NOTICES Federal Register / Vol. 71, No. 89 / Tuesday, May 9, 2006 / Notices revision of the license renewal guidance documents. DATES: Comments may be submitted by June 8, 2006. 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 to: Chief, Rules and Directives Branch, Office of Administration, U.S. Nuclear Regulatory Commission, Washington, DC 20555– 0001. Comments should be delivered to: 11545 Rockville Pike, Rockville, Maryland, Room T–6D59, between 7:30 a.m. and 4:15 p.m. on Federal workdays. Persons may also provide comments via e-mail at LNT@NRC.GOV. The NRC maintains an Agencywide Documents Access and Management System (ADAMS), which provides text and image files of NRC’s public documents. These documents may be accessed through the NRC’s Public Electronic Reading Room on the Internet at https:// www.nrc.gov/reading-rm/adams.html. Persons who do not have access to ADAMS or who encounter problems in accessing the documents located in ADAMS should contact the NRC Public Document Room (PDR) reference staff at 1–800–397–4209, 301–415–4737, or by e-mail at pdr@nrc.gov. FOR FURTHER INFORMATION CONTACT: Ms. Linh Tran, License Renewal Project Manager, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 20555– 0001; telephone 301–415–4103 or e-mail lnt@nrc.gov. SUPPLEMENTARY INFORMATION: Attachment 1 to this Federal Register notice, entitled Staff Position and Rationale for the Proposed License Renewal Interim Staff Guidance LR– ISG–2006–01: Plant-specific Aging Management Program for Inaccessible Areas of Boiling Water Reactor Mark I Steel Containment Drywell Shell contains the NRC staff’s rationale for publishing the proposed LR–ISG–2006– 01. Attachment 2 to this Federal Register notice, entitled Proposed License Renewal Interim Staff Guidance LR–ISG–2006–01: Plant-specific Aging Management Program for Inaccessible Areas of Boiling Water Reactor Mark I Steel Containment Drywell Shell, contains the guidance for developing the plant-specific aging management program. The NRC staff is issuing this notice to solicit public comments on the proposed LR–ISG–2006–01. After the NRC staff considers any public VerDate Aug<31>2005 15:42 May 08, 2006 Jkt 208001 comments, it will make a determination regarding the proposed LR–ISG. Dated at Rockville, Maryland, this 3rd day of May 2006. For the Nuclear Regulatory Commission. Pao-Tsin Kuo, Deputy Director, Division of License Renewal, Office of Nuclear Reactor Regulation. Attachment 1—Staff Position and Rationale for the Proposed License Renewal Interim Staff Guidance LR– ISG–2006–01: Plant-Specific Aging Management Program for Inaccessible Areas of Boiling Water Reactor Mark I Steel Containment Drywell Shell Staff Position Rationale The current license renewal guidance documents (LRGDs) do not provide sufficient guidance to address inaccessible areas of the Mark I steel containment drywell shell. Specifically, additional guidance is needed for inaccessible areas where the distance between the drywell shell and the surrounding concrete structure is too small for the successful performance of visual inspection. Past operating experience with Mark I steel containments indicates that when water is discovered in the bottom outside areas of the drywell (for example in the sand-pocket area), the most likely cause is the seepage through the space between the drywell shell and the shield concrete. Numerous requests for additional information (RAIs) on previous and current license renewal applications (LRAs) have been needed to obtain the information needed by the staff to perform its review. The purpose of the proposed LR–ISG–2006–01 is to provide guidance on the information that should be provided in the LRA to reduce the number of RAIs issued to the applicants. Specifically, the staff has determined that applicants for license renewal for a plant with a boiling water reactor Mark I steel containment should provide a plant-specific AMP to address the potential loss of material due to corrosion in the inaccessible areas of the Mark I steel containment drywell shell for the period of extended operation. Frm 00092 The drywell shell is a passive, longlived structure within the scope of license renewal that is subject to aging degradation. Pursuant to 10 CFR 54.21, the applicant must demonstrate that the effects of aging will be adequately managed so that the intended function will be maintained consistent with the current licensing basis for the period of extended operation. Attachment 2—Proposed License Renewal Interim Staff Guidance LR– ISG–2006–01: Plant-Specific Aging Management Program for Inaccessible Areas of Boiling Water Reactor Mark I Steel Containment Drywell Shell Introduction The NRC staff determined that applicants for license renewal for a plant with a boiling water reactor Mark I steel containment should provide a plant-specific aging management program (AMP) that addresses the potential loss of material due to corrosion in the inaccessible areas of the Mark I steel containment drywell shell for the period of extended operation. PO 00000 27011 Fmt 4703 Sfmt 4703 Line Item II.B1.1–2 of NUREG–1801, Volume 2, Revision 1, includes a provision for aging management of the Mark I steel containment drywell shells. However, the line item requires additional detail to address the inaccessible areas of the Mark I steel containment drywell shells. Specifically, the line item does not provide guidance when the distance between the steel drywell shell and the surrounding concrete structure is too small for the successful performance of visual examination. All Mark I containments are freestanding steel construction, except for Brunswick, Units 1 and 2. The Brunswick Mark I containment is a reinforced concrete drywell with a steel liner. A drywell shell is a free-standing steel structure with no concrete backing, whereas the steel liner of a drywell is a leak-tight membrane in direct contact with the concrete containment. Historical Background Information Notice (IN) 86–99, ‘‘Degradation of Steel Containments,’’ dated December 8, 1986, described an event related to the degradation of the drywell shell at Oyster Creek Nuclear Generating Station. IN 86–99, Supplement 1, dated February 1991, explained that the most likely cause of corrosion of the drywell shell in sandpocket areas (near the bottom of the drywell) and in the spherical portion of the drywell at higher elevations, was the water in the gap between the drywell and the concrete shield. The source of water was noted as leakage through the seal between the drywell and the refueling cavity. The IN supplement also noted that ultrasonic testing (UT) discovered minor corrosion in the cylindrical portion of the drywell. Discussion Generic Letter (GL) 87–05, ‘‘Request for Additional Information-Assessment E:\FR\FM\09MYN1.SGM 09MYN1 27012 Federal Register / Vol. 71, No. 89 / Tuesday, May 9, 2006 / Notices mstockstill on PROD1PC68 with NOTICES of Licensee Measures to Mitigate And/ Or Identify Potential Degradation of Mark I Drywells,’’ requested additional information regarding licensee actions to mitigate and/or identify potential degradation of boiling water reactor Mark I drywells. As a result, most licensees performed UT of their carbon steel drywell shells adjacent to the sand pocket region. In addition, many licensees established leakage monitoring programs for drain lines to identify leakage that may have resulted from refueling or spillage of water into the gap between the drywell and the surrounding concrete. UT performed as a result of GL 87–05 provided a set of data points to determine the drywell shell thickness that could be compared to the nominal/ minimum fabrication thickness and the minimum thickness required to withstand the postulated loads. These UT measurements taken during the 1987–1988 time frame fall approximately near the mid-point of the current 40-year operating license period for most plants with Mark I steel containments. The drywell shell is a passive, longlived structure within the scope of license renewal that is subject to aging degradation. Pursuant to 10 CFR 54.21, the applicant must demonstrate that the effects of aging will be adequately managed so that the intended function will be maintained consistent with the current licensing basis for the period of extended operation. On the basis of license renewal application reviews and industry operating experience, the NRC staff determined that a plant-specific aging management program (AMP) is needed to address the potential loss of material due to corrosion in the inaccessible areas of the Mark I steel containment drywell shell for the period of extended operation. Proposed Action In addressing Line Item II.B1.1–2 of NUREG–1801, Volume 2, Revision 1, applicants for license renewal for plants with a Mark I steel containment need to provide a plant-specific AMP that addresses the potential loss of material due to corrosion in the inaccessible areas of the Mark I steel containment drywell shell for the period of extended operation. In conducting the aging management review of the drywell shell, the applicant should consider the following: (1) Develop a corrosion rate that can be reasonably inferred from past UT examinations or establish a corrosion rate using representative samples in similar operating conditions, materials, VerDate Aug<31>2005 15:42 May 08, 2006 Jkt 208001 and environments. If degradation has occurred, provide a technical basis using the developed or established corrosion rate to demonstrate that the drywell shell will have sufficient wall thickness to perform its intended function through the period of extended operation. (2) Demonstrate that UT measurements performed in response to GL 87–05 did not show degradation inconsistent with the developed or established corrosion rate. (3) Where degradation has been identified in the accessible areas of the drywell, provide an evaluation that addresses the condition of the inaccessible areas for similar conditions. (4) To assure that there are no circumstances that would result in degradation of the drywell, demonstrate that moisture levels associated with accelerated corrosion rates do not exist in the exterior portion of the drywell shell, i.e., (1) the sand pocket area drains and/or the refueling seal drains are monitored periodically; (2) the top of the sand pocket area is sealed to exclude water accumulation in the sand pocket area; and/or alarms are used to monitor regions for moisture/leakage. (5) If moisture has been detected or suspected in the inaccessible area on the exterior of the drywell shell: (a) Include in the scope of license renewal any components that are identified as a source of moisture, such as the refueling seal, and perform an aging management review. (b) Identify surface areas requiring examination by implementing augmented inspections for the period of extended operation in accordance with the American Society of Mechanical Engineers (ASME) Section XI IWE–1240 as identified in Table IWE–2500–1, Examination Category E–C. (c) Use examination methods that are in accordance with ASME Section XI IWE–2500, which specifies: (i) Surface areas accessible from both sides shall be visually examined using a VT–1 visual examination method, (ii) Surface areas accessible from one side only shall be examined for wall thinning using an ultrasonic thickness measurement method, (iii) When ultrasonic thickness measurements are performed, one-foot square grids shall be used, and (iv) Ultrasonic measurements shall be used to determine the minimum wall thickness within each grid. The location of the minimum wall thickness shall be marked such that periodic reexamination of that location can be performed. (d) Demonstrate through use of augmented inspections performed in PO 00000 Frm 00093 Fmt 4703 Sfmt 4703 accordance with ASME Section XI IWE that corrosion is not occurring or that corrosion is progressing so slowly that the age-related degradation will not jeopardize the intended function of the drywell shell through the period of extended operation. (6) If the intended function of the drywell shell cannot be demonstrated for the period of extended operation (i.e., wall thickness is less than the minimum required thickness), identify actions that will be taken as part of the aging management program to ensure that the integrity of the drywell shell will be maintained through the period of extended operation. [FR Doc. E6–7000 Filed 5–8–06; 8:45 am] BILLING CODE 7590–01–P SECURITIES AND EXCHANGE COMMISSION Submission for OMB Review; Comment Request Upon Written Request, Copies Available From: Securities and Exchange Commission, Office of Filings and Information Services, Washington, DC 20549. Extension: Rule 11a–3, SEC File No. 270–321, OMB Control No. 3235–0358. Notice is hereby given that pursuant to the Paperwork Reduction Act of 1995 (44 U.S.C. 3501–3520), the Securities and Exchange Commission (‘‘Commission’’) has submitted to the Office of Management and Budget (‘‘OMB’’) a request for extension of the previously approved collections of information discussed below. Section 11(a) of the Investment Company Act of 1940 (‘‘Act’’) (15 U.S.C. 80a–11(a)) provides that it is unlawful for a registered open-end investment company (‘‘fund’’) or its underwriter to make an offer to the fund’s shareholders or the shareholders of any other fund to exchange the fund’s securities for securities of the same or another fund on any basis other than the relative net asset values (‘‘NAVs’’) of the respective securities to be exchanged, ‘‘unless the terms of the offer have first been submitted to and approved by the Commission or are in accordance with such rules and regulations as the Commission may have prescribed in respect of such offers.’’ Section 11(a) was designed to prevent ‘‘switching,’’ the practice of inducing shareholders of one fund to exchange their shares for the shares of another fund for the purpose of exacting additional sales charges. E:\FR\FM\09MYN1.SGM 09MYN1

Agencies

NUCLEAR REGULATORY COMMISSION

[Federal Register Volume 71, Number 89 (Tuesday, May 9, 2006)]
[Notices]
[Pages 27010-27012]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E6-7000]


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NUCLEAR REGULATORY COMMISSION


Proposed License Renewal Interim Staff Guidance LR-ISG-2006-01: 
Plant-Specific Aging Management Program for Inaccessible Areas of 
Boiling Water Reactor Mark I Steel Containment Drywell Shell 
Solicitation of Public Comment

AGENCY: Nuclear Regulatory Commission.

ACTION: Solicitation of public comment.

-----------------------------------------------------------------------

SUMMARY: The Nuclear Regulatory Commission (NRC) is soliciting public 
comment on its Proposed License Renewal Interim Staff Guidance LR-ISG-
2006-01. This LR-ISG proposes that applicants for license renewal for a 
plant with a boiling water reactor Mark I steel containment provide a 
plant-specific aging management program that addresses the potential 
loss of material due to corrosion in the inaccessible areas of their 
Mark I steel containment drywell shell for the period of extended 
operation.
    The NRC staff issues LR-ISGs to facilitate timely implementation of 
the license renewal rule and to review activities associated with a 
license renewal application (LRA). Upon receiving public comments, the 
NRC staff will evaluate the comments and make a determination to 
incorporate the comments, as appropriate. Once the NRC staff completes 
the LR-ISG, it will issue the LR-ISG for NRC and industry use. The NRC 
staff will also incorporate the approved LR-ISG into the next

[[Page 27011]]

revision of the license renewal guidance documents.

DATES: Comments may be submitted by June 8, 2006. 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 to: Chief, Rules and Directives 
Branch, Office of Administration, U.S. Nuclear Regulatory Commission, 
Washington, DC 20555-0001.
    Comments should be delivered to: 11545 Rockville Pike, Rockville, 
Maryland, Room T-6D59, between 7:30 a.m. and 4:15 p.m. on Federal 
workdays. Persons may also provide comments via e-mail at LNT@NRC.GOV. 
The NRC maintains an Agencywide Documents Access and Management System 
(ADAMS), which provides text and image files of NRC's public documents. 
These documents may be accessed through the NRC's Public Electronic 
Reading Room on the Internet at https://www.nrc.gov/reading-rm/
adams.html. Persons who do not have access to ADAMS or who encounter 
problems in accessing the documents located in ADAMS should contact the 
NRC Public Document Room (PDR) reference staff at 1-800-397-4209, 301-
415-4737, or by e-mail at pdr@nrc.gov.

FOR FURTHER INFORMATION CONTACT: Ms. Linh Tran, License Renewal Project 
Manager, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory 
Commission, Washington, DC 20555-0001; telephone 301-415-4103 or e-mail 
lnt@nrc.gov.

SUPPLEMENTARY INFORMATION: Attachment 1 to this Federal Register 
notice, entitled Staff Position and Rationale for the Proposed License 
Renewal Interim Staff Guidance LR-ISG-2006-01: Plant-specific Aging 
Management Program for Inaccessible Areas of Boiling Water Reactor Mark 
I Steel Containment Drywell Shell contains the NRC staff's rationale 
for publishing the proposed LR-ISG-2006-01. Attachment 2 to this 
Federal Register notice, entitled Proposed License Renewal Interim 
Staff Guidance LR-ISG-2006-01: Plant-specific Aging Management Program 
for Inaccessible Areas of Boiling Water Reactor Mark I Steel 
Containment Drywell Shell, contains the guidance for developing the 
plant-specific aging management program. The NRC staff is issuing this 
notice to solicit public comments on the proposed LR-ISG-2006-01. After 
the NRC staff considers any public comments, it will make a 
determination regarding the proposed LR-ISG.

    Dated at Rockville, Maryland, this 3rd day of May 2006.

    For the Nuclear Regulatory Commission.
Pao-Tsin Kuo,
Deputy Director, Division of License Renewal, Office of Nuclear Reactor 
Regulation.

Attachment 1--Staff Position and Rationale for the Proposed License 
Renewal Interim Staff Guidance LR-ISG-2006-01: Plant-Specific Aging 
Management Program for Inaccessible Areas of Boiling Water Reactor Mark 
I Steel Containment Drywell Shell

Staff Position

    The NRC staff determined that applicants for license renewal for a 
plant with a boiling water reactor Mark I steel containment should 
provide a plant-specific aging management program (AMP) that addresses 
the potential loss of material due to corrosion in the inaccessible 
areas of the Mark I steel containment drywell shell for the period of 
extended operation.

Rationale

    The current license renewal guidance documents (LRGDs) do not 
provide sufficient guidance to address inaccessible areas of the Mark I 
steel containment drywell shell. Specifically, additional guidance is 
needed for inaccessible areas where the distance between the drywell 
shell and the surrounding concrete structure is too small for the 
successful performance of visual inspection. Past operating experience 
with Mark I steel containments indicates that when water is discovered 
in the bottom outside areas of the drywell (for example in the sand-
pocket area), the most likely cause is the seepage through the space 
between the drywell shell and the shield concrete.
    Numerous requests for additional information (RAIs) on previous and 
current license renewal applications (LRAs) have been needed to obtain 
the information needed by the staff to perform its review. The purpose 
of the proposed LR-ISG-2006-01 is to provide guidance on the 
information that should be provided in the LRA to reduce the number of 
RAIs issued to the applicants. Specifically, the staff has determined 
that applicants for license renewal for a plant with a boiling water 
reactor Mark I steel containment should provide a plant-specific AMP to 
address the potential loss of material due to corrosion in the 
inaccessible areas of the Mark I steel containment drywell shell for 
the period of extended operation.
    The drywell shell is a passive, long-lived structure within the 
scope of license renewal that is subject to aging degradation. Pursuant 
to 10 CFR 54.21, the applicant must demonstrate that the effects of 
aging will be adequately managed so that the intended function will be 
maintained consistent with the current licensing basis for the period 
of extended operation.

Attachment 2--Proposed License Renewal Interim Staff Guidance LR-ISG-
2006-01: Plant-Specific Aging Management Program for Inaccessible Areas 
of Boiling Water Reactor Mark I Steel Containment Drywell Shell

Introduction

    Line Item II.B1.1-2 of NUREG-1801, Volume 2, Revision 1, includes a 
provision for aging management of the Mark I steel containment drywell 
shells. However, the line item requires additional detail to address 
the inaccessible areas of the Mark I steel containment drywell shells. 
Specifically, the line item does not provide guidance when the distance 
between the steel drywell shell and the surrounding concrete structure 
is too small for the successful performance of visual examination.
    All Mark I containments are free-standing steel construction, 
except for Brunswick, Units 1 and 2. The Brunswick Mark I containment 
is a reinforced concrete drywell with a steel liner. A drywell shell is 
a free-standing steel structure with no concrete backing, whereas the 
steel liner of a drywell is a leak-tight membrane in direct contact 
with the concrete containment.

Historical Background

    Information Notice (IN) 86-99, ``Degradation of Steel 
Containments,'' dated December 8, 1986, described an event related to 
the degradation of the drywell shell at Oyster Creek Nuclear Generating 
Station. IN 86-99, Supplement 1, dated February 1991, explained that 
the most likely cause of corrosion of the drywell shell in sand-pocket 
areas (near the bottom of the drywell) and in the spherical portion of 
the drywell at higher elevations, was the water in the gap between the 
drywell and the concrete shield. The source of water was noted as 
leakage through the seal between the drywell and the refueling cavity. 
The IN supplement also noted that ultrasonic testing (UT) discovered 
minor corrosion in the cylindrical portion of the drywell.

Discussion

    Generic Letter (GL) 87-05, ``Request for Additional Information-
Assessment

[[Page 27012]]

of Licensee Measures to Mitigate And/Or Identify Potential Degradation 
of Mark I Drywells,'' requested additional information regarding 
licensee actions to mitigate and/or identify potential degradation of 
boiling water reactor Mark I drywells. As a result, most licensees 
performed UT of their carbon steel drywell shells adjacent to the sand 
pocket region. In addition, many licensees established leakage 
monitoring programs for drain lines to identify leakage that may have 
resulted from refueling or spillage of water into the gap between the 
drywell and the surrounding concrete.
    UT performed as a result of GL 87-05 provided a set of data points 
to determine the drywell shell thickness that could be compared to the 
nominal/minimum fabrication thickness and the minimum thickness 
required to withstand the postulated loads. These UT measurements taken 
during the 1987-1988 time frame fall approximately near the mid-point 
of the current 40-year operating license period for most plants with 
Mark I steel containments.
    The drywell shell is a passive, long-lived structure within the 
scope of license renewal that is subject to aging degradation. Pursuant 
to 10 CFR 54.21, the applicant must demonstrate that the effects of 
aging will be adequately managed so that the intended function will be 
maintained consistent with the current licensing basis for the period 
of extended operation.
    On the basis of license renewal application reviews and industry 
operating experience, the NRC staff determined that a plant-specific 
aging management program (AMP) is needed to address the potential loss 
of material due to corrosion in the inaccessible areas of the Mark I 
steel containment drywell shell for the period of extended operation.

Proposed Action

    In addressing Line Item II.B1.1-2 of NUREG-1801, Volume 2, Revision 
1, applicants for license renewal for plants with a Mark I steel 
containment need to provide a plant-specific AMP that addresses the 
potential loss of material due to corrosion in the inaccessible areas 
of the Mark I steel containment drywell shell for the period of 
extended operation.
    In conducting the aging management review of the drywell shell, the 
applicant should consider the following:
    (1) Develop a corrosion rate that can be reasonably inferred from 
past UT examinations or establish a corrosion rate using representative 
samples in similar operating conditions, materials, and environments. 
If degradation has occurred, provide a technical basis using the 
developed or established corrosion rate to demonstrate that the drywell 
shell will have sufficient wall thickness to perform its intended 
function through the period of extended operation.
    (2) Demonstrate that UT measurements performed in response to GL 
87-05 did not show degradation inconsistent with the developed or 
established corrosion rate.
    (3) Where degradation has been identified in the accessible areas 
of the drywell, provide an evaluation that addresses the condition of 
the inaccessible areas for similar conditions.
    (4) To assure that there are no circumstances that would result in 
degradation of the drywell, demonstrate that moisture levels associated 
with accelerated corrosion rates do not exist in the exterior portion 
of the drywell shell, i.e., (1) the sand pocket area drains and/or the 
refueling seal drains are monitored periodically; (2) the top of the 
sand pocket area is sealed to exclude water accumulation in the sand 
pocket area; and/or alarms are used to monitor regions for moisture/
leakage.
    (5) If moisture has been detected or suspected in the inaccessible 
area on the exterior of the drywell shell:
    (a) Include in the scope of license renewal any components that are 
identified as a source of moisture, such as the refueling seal, and 
perform an aging management review.
    (b) Identify surface areas requiring examination by implementing 
augmented inspections for the period of extended operation in 
accordance with the American Society of Mechanical Engineers (ASME) 
Section XI IWE-1240 as identified in Table IWE-2500-1, Examination 
Category E-C.
    (c) Use examination methods that are in accordance with ASME 
Section XI IWE-2500, which specifies:
    (i) Surface areas accessible from both sides shall be visually 
examined using a VT-1 visual examination method,
    (ii) Surface areas accessible from one side only shall be examined 
for wall thinning using an ultrasonic thickness measurement method,
    (iii) When ultrasonic thickness measurements are performed, one-
foot square grids shall be used, and
    (iv) Ultrasonic measurements shall be used to determine the minimum 
wall thickness within each grid. The location of the minimum wall 
thickness shall be marked such that periodic reexamination of that 
location can be performed.
    (d) Demonstrate through use of augmented inspections performed in 
accordance with ASME Section XI IWE that corrosion is not occurring or 
that corrosion is progressing so slowly that the age-related 
degradation will not jeopardize the intended function of the drywell 
shell through the period of extended operation.
    (6) If the intended function of the drywell shell cannot be 
demonstrated for the period of extended operation (i.e., wall thickness 
is less than the minimum required thickness), identify actions that 
will be taken as part of the aging management program to ensure that 
the integrity of the drywell shell will be maintained through the 
period of extended operation.

[FR Doc. E6-7000 Filed 5-8-06; 8:45 am]
BILLING CODE 7590-01-P

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