ML18137A133
| ML18137A133 | |
| Person / Time | |
|---|---|
| Issue date: | 05/17/2018 |
| From: | George Thomas NRC/NRR/DE/ESEB |
| To: | |
| Brady B, NRR-DMLR 415-2981 | |
| Shared Package | |
| ML18137A131 | List: |
| References | |
| Download: ML18137A133 (11) | |
Text
NRC Staffs Licensing Perspectives on Irradiation Effects on Concrete for SLR George Thomas Office of Nuclear Reactor Regulation, USNRC May 17, 2018
Overview
- Background
- NRC Guidance for SLR
- Key Expectations 2
=
Background===
Technical Concern:
Expanded Material Degradation Assessment (EMDA) Report (NUREG/CR-7153) Vol 4, Aging of Concrete and Civil Structures, identifies radiation Radiation effects on concrete as low-knowledge but high Effects significance/susceptibility for SLR.
NRC Publications Commission Directive
- NUREG/CR-7171, A Review of the
- SECY-14-0016: the NRC staff is conducting Effects of Radiation on the a series of activities to prepare for review Microstructure and Properties of of subsequent license renewal (SLR)
Concretes Used in Nuclear Power applications Plants
- SRM to SECY-014-0016: staff directed to
- NUREG/CR-7153 Vol. 4, Aging of keep the Commission informed regarding Concrete and Civil Structures progress on this issue 3
NRC Guidance for SLR
- Generic Aging Lessons Learned Report updated for Subsequent License Renewal (GALL-SLR) July 2017
- Aging effects of reduction of strength and loss of mechanical properties due to irradiation (and radiation induced heating) 4
NRC Guidance for SLR
- Standard Review Plan for Subsequent License Renewal (SRP-SLR): Table 3.5-1, new item 97
- Further Evaluation is recommended of a plant-specific program to manage these aging effects for PWRs and BWRs
- SRP-SLR Section 3.5.2.2.2.6 and Section 3.5.3.2.2.6 5
NRC Guidance for SLR From SRP-SLR Section 3.5.2.2.2.6:
Further evaluation is recommended of Expectation:
a plant-specific programif the Plant-Specific estimated (calculated) fluence levels or Fluence irradiation dose received by any portion Calculation of the concrete from neutron (fluence cutoff energy E > 0.1 MeV) or gamma +
radiation exceeds the respective Plant-Specific threshold level [1 x 1019 neutrons/cm2 Operating and 1 x 108 Gy] during the subsequent Experience PEO or if plant-specific OE of concrete Review irradiation degradation exists that may impact intended functions.
6
NRC Guidance for SLR Fluence levels < Threshold limits AND Further Evaluation No OE impacting intended criteria satisfied functions Address the aging effect of loss of Fluence levels > Threshold limits strength of concrete OR structures due to OE impacting intended functions irradiation for subsequent period of extended operation 7
NRC Guidance for SLR Addressing Further Evaluation Criteria for irradiated concrete aging effect (plants that exceed fluence threshold)
Analysis Combination OR Aging Management Program (for example, analysis to 70 years and plans/calculations for Other subsequent structural (e.g. Structural modification)
Modification, Mitigation of Radiation Effects)
- Applicant must demonstrate continued ability of structures to perform intended functions through the subsequent period of extended operation at the time of the SLRA submission 8
Key Expectations for SLR (with respect to SRP/GALL-SLR guidance)
- Disposition of the irradiated concrete Further Evaluation (FE) should be based on a plant-specific fluence calculation, regardless of plant design
- Applicants can opt to perform a damage analysis, provide an aging management program, or other method to satisfy Further Evaluation Criteria
- To date, NRC has not approved any topical report as bounding of degradation due to irradiation
- As such, SLR applicants should not use topical reports solely to disposition the aging effects related to irradiation 9
Key Expectations for SLR (with respect to SRP/GALL-SLR guidance)
- If applicant chooses to perform an analysis to address FE:
- It is not necessary (or preferable) to provide the entire calculation/analysis on the docket in the SLRA
- However, SLRA should clearly indicate existence of or provide reference to a plant-specific analysis or calculation
- Referenced analyses/calculations should include:
- Reference to drawings identifying dimensions, distances, anchorages, materials used, and placement of reinforcement and embedments
- Plant-specific loadings and load combinations (or a bounding case)
- Design Codes used
- Consideration of combined effects of environmental factors, as applicable
- Justification for the characterization of load-carrying mechanisms used (e.g., assumed concrete and steel bond strength) 10
QUESTIONS?