ML003693782
| ML003693782 | |
| Person / Time | |
|---|---|
| Issue date: | 03/20/2000 |
| From: | Charemagne Grimes NRC/NRR/DRIP/RLSB |
| To: | Walters D Nuclear Energy Institute |
| Lee S | |
| References | |
| Download: ML003693782 (7) | |
Text
4.8 OTHER PLANT-SPECIFIC TIME LIMITED AGING ANALESES Review Responsibilities Primary - Branch responsible for engineering Secondary - Other branches responsible for systems, as appropriate 4.8.1 Areas of Review There are certain plant-specific safety analyses which may have been based on an explicitly assumed 40-year plant life (for example, aspects of the reactor vessel design). Pursuant to 10 CFR 54.21(c), a license renewal applicant is required to evaluate time-limited aging analyses (TLAAs). The definition of TLAAs is provided in 10 CFR 54.3 and Section 4.1of this standard review plan.
TLAA requirements may have evolved and are plant-specific. The adequacy of the plant's current licensing basis (CLB), which includes TLAAs, is not an area of review. Potential concerns or enhancements regarding the CLB are to be addressed under the backfit rule (10 CFR 50.109) and are separate from the license renewal process.
License renewal reviews focus on the period of extended operation. Pursuant to 10 CFR 54.30, if the reviews show that the TLAAs are not sufficient to provide reasonable assurance during the current license term that licensed activities will be conducted in accordance with the CLB, the licensee is required to take measures under its current license to ensure that the intended function of those structures or components will be maintained in accordance with the CLB throughout the term of the current license. The adequacy of the measures for the term of the current license is not an area of review for license renewal.
Pursuant to 10 CFR 54.21(c), an applicant must provide a listing of TLAAs and plant-specific exemptions that are based on TLAAs. The staff reviews the applicants identification of TLAAs and exemptions that are based on TLAAs separately following the guidance in Section 4.1 of this standard review plan.
Based on lessons learned in the review of the initial license renewal applications, the staff has developed review procedures for the evaluation of certain TLAAs. If an applicant identifies these TLAAs as applicable to its plant, the staff reviews them separately following the guidance in Sections 4.2 through 4.7 of this standard review plan. The staff reviews other TLAAs that are identified by the applicant following the generic guidance in this review plan section. The staff from branches responsible for systems may be requested to assist in the review, as appropriate.
The following areas relating to a TLAA are reviewed:
4.8.1.1 Time-Limited Aging Analysis The evaluation of the TLAA for the period of extended operation is reviewed.
4.8.1.2 FSAR Supplement The FSAR supplement summarizing the evaluation of the TLAA for the period of extended operation in accordance with 10 CFR 54.21(d) is reviewed.
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4.8.2 Acceptance Criteria The acceptance criteria for the areas of review described in Subsection 4.8.1 of this review plan section define acceptable methods for meeting the requirements of the Commission's regulations in 10 CFR 54.21(c)(1).
4.8.2.1 Time-Limited Aging Analysis Pursuant to 10 CFR 54.21(c)(1)(i) through (iii), an applicant must demonstrate one of the following for the TLAAs:
(i) The analyses remain valid for the period of extended operation; (ii) The analyses have been projected to the end of the extended period of operation; or (iii) The effects of aging on the intended function(s) will be adequately managed for the period of extended operation.
4.8.4.2.2 FSAR Supplement The specific criterion for meeting 10 CFR 54.21(d) is:
The summary description of the evaluation of TLAAs for the period of extended operation in the FSAR supplement provides appropriate description such that later changes can be controlled by 10 CFR 50.59. The description should contain information associated with the TLAAs regarding the basis for determining that aging effects are managed in the period of extended operation.
4.8.3 Review Procedures The requirement of TLAAs captures, for renewal review, certain plant-specific aging analyses that are explicitly based on the duration of the current operating license of the plant. The concern is that these aging analyses do not cover the period of extended operation. Unless these analyses are evaluated, there is no assurance that the systems, structures, and components addressed by these analyses can perform their intended function(s) during the period of extended operation.
For each area of review described in Subsection 4.8.1 of this review plan section, the following review procedures are followed:
4.8.3.1 Time-Limited Aging Analysis For the TLAA identified, the review procedures depending on the applicant's choice, that is, 10 CFR 54.21(c)(1)(i), (ii), or (iii), are:
4.8.3.1.1 10 CFR 54.21(c)(1)(i)
Justification provided by the applicant is reviewed to verify that the existing analyses are valid for the period of extended operation. The existing analyses should be shown to be bounding even during the period of extended operation.
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An applicant should describe the TLAA with respect to the objectives of the analysis, conditions, and assumptions used in the analysis, acceptance criteria, relevant aging effects, and intended function(s). The applicant should show that (1) the conditions and assumptions used in the analysis already address the relevant aging effects for the period of extended operation, and (2) acceptance criteria are maintained to provide reasonable assurance that the intended function(s) is maintained for renewal. Thus, no reanalysis is necessary for renewal.
If the TLAA has to be modified or recalculated to extend the period of evaluation to cover the period of extended operation, the re-evaluation should be addressed under 10 CFR 54.21(c)(1)(ii).
4.8.3.1.2 10 CFR 54.21(c)(1)(ii)
The revised analyses are reviewed to verify that the period of evaluation of the analyses is extended such that they are valid for the period of extended operation, for example, 60 years.
The applicable analysis technique can be the one that is in effect in the plant's CLB at the time of renewal application.
An applicant may recalculate the TLAA using a 60 year period to show that the TLAA acceptance criteria continue to be satisfied for the period of extended operation. The applicant may also revise the TLAA by recognizing and re-evaluating any overly conservative conditions and assumptions. Examples include relaxing overly conservative assumptions in the original analysis, using new or refined analytical techniques, and performing the analysis using a 60 year period.
As applicable, the plant's code of record should be used for the re-evaluation or the applicant may update to a later code edition pursuant to 10 CFR 50.55a. In the latter case, the reviewer verifies that the requirements in 10 CFR 50.55a are met.
4.8.3.1.3 10 CFR 54.21(c)(1)(iii)
Under this option, an applicant would propose to manage the aging effects associated with the TLAA by an aging management program, in the same manner as the integrated plant assessment (IPA) in 10 CFR 54.21(a)(3). The reviewer reviews the applicants aging management program to verify that the effects of aging on the intended function(s) will be adequately managed consistent with the CLB for the period of extended operation.
An applicant should identify the structures and components associated with the TLAA. The TLAA should be described with respect to the objectives of the analysis, conditions, and assumptions used in the analysis, acceptance criteria, relevant aging effects and intended function(s). The reviewer may use the guidance provided in Branch Technical Position RLSB-1 of this standard review plan to ensure that the effects of aging on the structure and component intended function(s) are adequately managed for the period of extended operation.
4.8.3.2 FSAR Supplement The reviewer verifies that the applicant has provided a FSAR supplement on the description of the evaluation of the TLAA. The summary description of the evaluation of TLAA for the period of extended operation in the FSAR supplement is reviewed to verify that it provides an appropriate description such that later changes can be controlled by 10 CFR 50.59. The description should contain information associated with the TLAA regarding the basis for 4.8-3 Draft - 3/20/00
determining that aging effects are managed in the period of extended operation. Sections 4.2 through 4.7 of this standard review plan contains examples of acceptable FSAR supplement information for TLAA evaluation.
4.8.4 Evaluation Findings The reviewer verifies that sufficient and adequate information has been provided to satisfy the provisions of this review plan section and that the staff's evaluation supports conclusions of the following type, depending on the applicants choice of 10 CFR 54.21(c)(1)(i), (ii), or (iii), to be included in the staff's safety evaluation report:
The staff evaluation concludes that the applicant has provided an acceptable demonstration, pursuant to 10 CFR 54.21(c)(1), that, for the (name of specific) TLAA, (i) the analyses remain valid for the period of extended operation, (ii) the analyses have been projected to the end of the period of extended operation, or (iii) the effects of aging on the intended function(s) will be adequately managed for the period of extended operation. The staff also concludes that the FSAR supplement contains an appropriate summary description of this TLAA evaluation for the period of extended operation.
4.8.5 Implementation Except in those cases in which the applicant proposes an acceptable alternative method, the method described herein will be used by the staff in its evaluation of conformance with Commission regulation.
4.8.6 References None.
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