ML20056F093
| ML20056F093 | |
| Person / Time | |
|---|---|
| Issue date: | 07/30/1993 |
| From: | Russell W Office of Nuclear Reactor Regulation |
| To: | Rasin W NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| References | |
| NUDOCS 9308260052 | |
| Download: ML20056F093 (17) | |
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Mr. William Rasin Vice President & Director, Technical Division Nuclear Management and Resources Council 1776 Eye Street, N.W., Suite 300 Washington, DC 20006-2496
SUBJECT:
NRC STAFF ACTION PLANS CONCERNING THE ISSUES OF ENVIRONMENTAL QUALIFICATION AND FATIGUE ANALYSIS OF COMPONENTS i
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Dear Mr. Rasin:
Enclosed for your information are copies of the NRC staff's task action plans for the resolution of the environmental qualification and fatigue issues that were identified during the license renewal deliberations.
The following supervisors have been designated as the points of contact for these actions plans:
Environmental Qualification Task Action Plan: George T. Hubbard, Jr., SPLB, at 504-2870 i
Fatigue Action Plan: Terence L. Chan, EMEB, at 504-2169 Please contact these individuals if you have any questions regarding these staff action plans.
Sincerely, ORIGINM. SIGNED BY W.T. RUSSELL William T. Russell, Associate Director
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for Inspection and Technical Assessment j
Office of Nuclear Reactor Regulation
Enclosures:
- 1. Environmental Qualification Task Action Plan
- 2. Fatigue Action Plan Distribution:
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ENVIRONMENTAL QUALIFICATION (EQ) 10 CFR 50.49 t
TASK ACTION PLAN I
June 16,1993 OFFICE OF NUCLEAR REACTOR REGULATION DIVISION OF SYSTEMS SAFETY AND ANALYSIS PLANT SYSTEMS BRANCH l
BALANCE OF PLANT SYSTEMS SECTION i
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component reliabilities are reduced in the presence of a harsh environment, l
(2) the magnitude of the impact on core damage frequency is plant specific, and (3)'the lack of reliability data and limitations in current probabilistic i
risk assessment models result in significant uncertainty.
Based on the results of the preliminary risk scoping study, the staff concluded that a more c
detailed EQ risk assessment should be completed.
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Separate from the license renewal and risk assessment activities associated with EQ, the staff recently completed an assessment of the NRC fire protection program in response to issues that were raised by the Office of the Inspector General (OIG) in a report dated August 12, 1992. The staff's assessment of the fire protection program dated February 27, 1993, identified a number of weaknesses and made specific recommendations fcr programmatic improvements.
In view of the weaknesses that were identified relative to the NRC fire protection program, the staff concluded that other programs such as EQ should also be reviewed to identify and correct any programmatic weaknesses that may exist.
Although the original issue involved whether the EQ requirements for older plants were adequate for license renewal, the issue has evolved into whether 1
existing EQ standards and regulations are adequate for all operating reactors.
l With the preliminary risk scoping assessment indicating that inadequate EQ f
could be a significant contributor to core damage frequency, the staff has determined that focused staff and management attention are necessary to fully address EQ concerns. This TAP will focus NRC staff attention to:
(1) evaluate differences that currently exist in EQ requirements between older and newer plants; (2) assess the adequacy of accelerated aging practices that are currently used for demonstrating equipment qualification; and (3) perform a programmatic review of EQ requirements to identify and resolve any other EQ issues that may exist.
Although this TAP describes planned actions, it should be recognized that this is an evolving issue and the actions, as described, may be modified as additional information is obtained through further research and review of i
industry operating experience.
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EQ Action Plan page 2 pertaining to EQ. Currently, SPLB is in the process of documenting the I
results.
b.
Review Fire Protection Reassessment Report Scope - SPLB will review recommendations from the NRC staff's reassessment of the fire protection program dated 2/27/93, and identify specific issues that could relate to EQ.
Completion Date - 7/93 Status - SPLB is reviewing the fire protection reassessment report.
I c.
Elicit opinions from others (Regions, EQ experts).
Scope - SPLB will survcy NRC regional offices, NRC headquarters, and industry experts for potential problems with environmental qualification and evaluate the results of the survey.
Completion Date - 12/93 Status - SPLB is developing the survey questions, d.
Review existing EQ program requirements.
Scoce - SPLB will review EQ program requirements to determine whether EQ issues, in addition to those already identified, exist and need to be addressed.
SPLB will review 10 CFR 50.49, NUREG-0588, D0R Guidelines, Reg Guide 1.89, IEEE/323-1971, IEEE/323-1974, etc. to determine if potential programmatic problems exist.
Completion Date - 8/93 Status - SPLB is reviewing the EQ program requirements in order to determine if potential programmatic problems exist.
e.
Review NRC audit / inspection practices.
Scope - SPLB will review EQ inspection guidance and a sample of reports from licensee EQ inspections and vendor EQ inspections to identify potential programmatic problems. SPLB will review inspection findings, i
enforcement policy (Generic Letter 88-07), enforcement actions, and history.
Completion Date - 10/93 Status - SPLB is scheduled to begin the review in August 1993.
f.
Review licensee implementation practices.
Scope - SPLB will review and evaluate selected licensees' implementation i
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EQ Action Plan page 4 c.
Review operating experience data.
Scope - SPLB, with contractor assistance, will review Licensee Event Report (LER) and Nuclear Plant Reliability Data System (NPRDS) data, and will identify and evaluate whether environmentally qualified equipment is experiencing age-related degradation.
Completion Date - 12/93 Status - SPLB reviewed the LER data base that contains 72 reports of cables that failed under normal operating conditions for various reasons. SPLB issued a 50W for contractor assistance to TAMS on 6/4/93.
The SPLB contractor will be conducting a more detailed review.
d.
Review TMI information via DOE.
Scope - RES, with SPLB assistance, will obtain and evaluate information on equipment failures during the TMI accident.
Completion Date - 4/94 Status - RES is contacting the Department of Energy to obtain information.
e.
EQ Data Base Scope - SPLB, with RES input, will develop an integrated data base using qualification test reports, research tests, and other test activities related to qualified equipment to provide a source of information for future EQ activities.
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Completion Date - 8/94 Status - SPLB will be developing the integrated data base in fiscal year j
1994.
i 5.
Risk Assessment a.
Preliminary Risk Scoping Study Scope - The Probabilistic Safety Assessment Branch (SPSB) of NRR will perform a preliminary risk scoping analysis to quantify the risk impact of environmentally qualified electrical equipment.
Completion Date - 3/30/93 Status - SPSB completed a preliminary risk scoping analysis which was issued on 4/8/93, in memorandum to T. Murley from A. Thadani.
EQ Action Plan page 6 c.
Impact of new source term on EQ.
i Scope - Since the usage of a new source term is an ongoing activity, SPLB and RES will follow its development and analyze its impact on EQ i
issues.
Comoletion Date - 7/94 Status - SPLB and RES will start this effort in 1994.
7.
Options for Resolution Scope - NRR and RES will develop options for the resolution of EQ concerns, including Generic Letter, rule change, or documentation of acceptability of the current EQ rule and standards.
In developing options, the staff must consider the impact of changes on license renewal, because the regulatory initiative will carry over into the renewal term. The possibility of capture of EQ condition monitoring and upgrades under the maintenance rule should be considered.
The resolutien must address all EQ components and should not be restricted to cables.
It may be necessary to develop new acceptance criteria for EQ testing, elongation testing, indenter testing, etc.
Comoletion Date - 10/94 Status - N/A 8.
Implementation a.
NRC Regulatory Initiative Scope - NRR and RES will decide on appropriate regulatory action; plan and implement the action; and document the basis for the action.
Possible actions to be considered by NRR and RES may include a Generic i
Letter or Rulemaking.
Completion Date - TBD i
Status - N/A b.
Industry Action /NRC Review and Verification Scope - NRR will monitor licensee actions in response to the NRC staff's i
initiative on EQ. NRR and NRC Regional Offices will verify that licensees have taken appropriate action to correct any EQ problems.
Completion Date - TBD Status - N/A
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ENCLOSURE 2
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FATIGUE ACTION PLAN DEFINITION OF ISSUES In developing criteria for the evaluation of applications for license renewal, the staff developed a draft branch technical position on fatigue evaluation procedures.
Subsequent discussions within the staff and between the staff and the industry identified three major issues regarding the fatigue evaluation of candidate plants for license renewal (and current operating plants).
These issues are:
1.
Many older vintage nuclear power plants have components of the reactor coolant pressure boundary that were designed to codes that did not require the explicit fatigue analysis required by the current ASME Code.
A concern with the adequacy of the fatigue design of these components for the plant life was identified.
2.
Current test data show that the ASME design fatigue curves may not be conservative for nuclear power plant primary system environments. A i
concern with the adequacy of the fatigue design of components designed i
using these ASME curves was also identified.
3.
The appropriate corrective actior. to be taken when the calculated fatigue allowable limits have been exceeded (CUF>1) is the subject of controversy. A staff position regarding this issue is needed.
i DISCUSSION OF OPEN ISSUES i
For older vintage plants, components of the reactor coolant pressure boundary were designed to codes, such as ANSI B31.1, that did not require an explicit fatigue analysis of the components.
Because the ASME Code currently requires j
a fatigue evaluation of the components of the reactor coolant pressure boundary, this leads to a question with respect to the adequacy in terms of j
i fatigue resistance of these older vintage plants.
In order to assess the fatigue resistance of the older vintage plants, an actual fatigue evaluation of a sample of the components in these plants is planned.
This sample will be selected using the results of fatigue analyses from similar systems or components in plants for which the fatigue analyses have been performed as a guide in selecting critical locations.
In addition, some recent test data indicate that the effects of the LWR environments could significantly reduce the fatigue resistance of materials.
The ASME Code design fatigue curves were based primarily on strain-controlled fatigue tests of small polished specimens at room temperature in air.
Although factors of safety were applied to the best fit curves to cover effects such as size and data scatter, some of the recent test data indicate that these factors of safety may not be adequate to encompass the environmental effects.
In order to assess the significance of the recent test data, an actual fatigue evaluation of a sample of components in plants where Code fatigue analyses have been performed is planned.
These evaluations will use interim or proposed fatigue curves that account for the environmental test data. The sample will be selected based o' the most critical locations identified by the existing Code fatigue analyses.
The new fatigue evaluations
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Estimated Completion Date: August 1, 1994 Estimated Level of Effort:
10 staff weeks OTHER CONSIDERATIONS This is a technical action plan that is necessary to determine the scope of the problem. A regulatory licensing action plan will be developed to address the implementation of the final staff position if required.
CONTACT J. Fair 504-2759