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{{#Wiki_filter: | {{#Wiki_filter:FINAL SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION TOPICAL REPORT EMF-93-177, REVISION 1, SUPPLEMENT 2P, REVISION 1 MECHANICAL DESIGN FOR BWR FUEL CHANNELS: Z4B MATERIAL FRAMATOME INC. | ||
PROJECT NO. 728/DOCKET NO. 99902041 | |||
==1.0 INTRODUCTION== | |||
***}} | By letter dated July 25, 2018 (Ref. 1), Framatome Inc. (Framatome) requested review and approval of an advanced zirconium (Zr) alloy, Z4B, for batch application to existing boiling water reactor (BWR) fuel channel designs. Framatome developed Z4B to address excessive control blade friction due to abnormal fuel channel bow and bulge primarily caused by hydrogen-assisted accelerated irradiation-induced differential growth, galvanic style shadow corrosion from low exposure control blade insertion, and channel deformation/creep from differential pressure, that was experienced by the nuclear power industry when it transitioned to Zr-2 based fuel channel materials and thick-thin channel mechanical designs in the 2000s. | ||
Z4B is a Zr-4 based material with increased alloying elements of iron (Fe) and chromium (Cr). It is manufactured with one of two heat options, either fully recrystallized annealed (RXA) or beta-quenched (BQ). | |||
In 2017, the U.S. Nuclear Regulatory Commission (NRC) staff approved Framatomes expanded lead use channel (LUC) program for the Z4B zirconium alloy (Ref. 4). The purpose of the expanded LUC program was to allow greater numbers of channels to be exposed to varying in-reactor operating strategies, nuclear conditions, and water chemistry in order to gain experience and gather data for batch application. Reference 4 describes the LUC program and Reference 1 summarizes the results of the LUC program. Section 5.0 of this safety evaluation (SE) addresses the limitations and conditions (L&Cs) imposed on the use of Z4B channels by Reference 4 during the LUC program and any new L&Cs as a result of this review. | |||
It is important to note that Framatome is not requesting any new performance models for the Z4B material, even though it has improved characteristics. Nor is Framatome requesting any changes to the methodology used in a licensees safety analyses (SAs) evaluation models (EMs) for licensing Framatomes fuel products. Reference 1 justifies the existing Zr-4 based performance models (Refs. 2 and 3) and their application within a licensees SA methods is applicable and conservative for use with Z4B. | |||
EMF-93-177, Revision 1, Supplement 2P, Revision 1, Mechanical Design for BWR Fuel Channels: Z4B Material, will be referred to as EMF-93-177 in the remainder of this SE. | |||
Enclosure | |||
==2.0 REGULATORY EVALUATION== | |||
Regulatory guidance for the review of fuel system materials and designs and adherence to General Design Criteria (GDC)-10, GDC-27, and GDC-35 is provided in NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants (SRP), Section 4.2, Fuel System Design (Ref. 5). In accordance with SRP Section 4.2, the objectives of the fuel system safety review are to provide assurance that: | |||
* The fuel system is not damaged as a result of normal operation and anticipated operational occurrences (AOOs). | |||
* Fuel system damage is never so severe as to prevent control rod insertion when it is required. | |||
* The number of fuel rod failures is not underestimated for postulated accidents, and coolability is always maintained. | |||
The main focus of the limited SRP guidance with respect to BWR fuel bundle channels is control blade interference and insertability. SRP Section 4.2.II.1.A.v states: | |||
Control blade/rod, channel, and guide tube bow as a result of (1) differential irradiation growth (from fluence gradients), (2) shadow corrosion (hydrogen uptake results in swelling), and (3) stress relaxation, which can impact control blade/rod insertability from interference problems between these components. For BWRs, the effects of shadow corrosion should be considered for new control blade or channel designs, dimensions (e.g., the distance between control blade and channel is important), or materials. The effects of channel bulge should also be considered for interference problems for BWRs. | |||
Design changes can alter the pressure drop across the channel wall, thus necessitating an evaluation of such changes. Channel material changes can also impact the differential growth, stress relaxation, and the amount of bulge and therefore must be evaluated. If interference is determined to be possible, tests are needed to demonstrate control blade/rod insertability consistent with assumptions in safety analyses. Additional in-reactor surveillance (e.g., insertion times) may also be necessary for new designs, dimensions, and materials to demonstrate satisfactory performance. | |||
With respect to ensuring control blade insertability under externally applied loads (i.e., safe shutdown earthquake and loss-of-coolant accident), SRP 4.2 Appendix A, Section IV states: | |||
For a BWR, several conditions must be met to demonstrate control blade insertability | |||
- (1) combined loads on the channel box must remain below the allowable value defined above for components other than grids (otherwise, additional analysis is needed to show that the deformation is not severe enough to prevent control blade insertion) and (2) vertical liftoff forces must not unseat the lower tieplate from the fuel support piece such that the resulting loss of lateral fuel bundle positioning could interfere with control blade insertion. | |||
The NRC staffs review of EMF-93-177 is to ensure that the introduction of Z4B does not adversely impact the ability of existing BWR channel designs to satisfy these requirements. | |||
==3.0 TECHNICAL EVALUATION== | |||
The NRC staffs review of the EMF-93-177 is summarized below: | |||
* Verify that the fuel channel design requirements are consistent with regulatory criteria identified in SRP 4.2 or are otherwise acceptable and justified. | |||
* Verify that the Z4B channel design satisfies regulatory requirements. | |||
* Verify that the Framatome experience database (in-reactor residence, post-irradiation examinations, and out-of-pile testing) supports the operating limits being requested and provides reasonable assurance that no anomalous behavior will occur during batch implementation. | |||
* Verify that the impact of the Framatome channel designs on the reload design methodology, safety analyses, and setpoints has been properly addressed. | |||
* Define the range of applicability and allowed manufacturing tolerances/variances (e.g., alloy composition, microstructure). | |||
* Define future surveillance and reporting requirements as necessary. The NRC staffs review builds upon the Z4B enhanced LUC program (Ref. 4) and the operating experience and data collected from past and ongoing surveillance programs. | |||
3.1 BWR Channel Design Requirements The design requirements for Framatomes BWR channels are described in References 2 and 3 and are unchanged for Z4B materials and heat treatments. These design requirements have been previously approved and are consistent with the SRP and, therefore, remain acceptable. | |||
3.2 Z4B Composition and Microstructure The composition of Z4B is similar to that of Zry-4 as defined in ASTM B352/B352M, with the exceptions that Z4B has slightly higher Fe and Cr contents. The exact material contents are proprietary and will not be restated here. Zry-4 was developed based on Zry-2 with the intent to remove Ni from the alloy and avoid the high hydrogen pickup which is seen in Zry-2 which is thought to be a primary driver of irradiation growth in zirconium materials. Z4B and the Zircaloys are composed of about 98 weight percent zirconium and have a hexagonal crystal structure at room and service temperatures. Z4B also has improved corrosion resistance that may be necessary for some licensees challenging reactor chemistry environments. | |||
Framatome's Z4B is made in either the RXA or BQ final microstructure. The BQ process results in a quasi-isotropic texture that has demonstrated the ability to reduce the irradiation growth rate of Zircaloys. | |||
3.3 Z4B Material Properties The unirradiated Z4B properties (melting point, density, heat capacity, thermal conductivity, and thermal expansion) are nearly identical to those of Zr-4 which is fully expected. The slight increase of Fe and Cr in Z4B has an insignificant effect on parameters impacting elastic properties including Young's modulus, and Poisson's ratio. These parameters include bond length, coordination number, and charge of the metal ion. It is therefore acceptable to apply the existing Zr-4 based properties to Z4B. | |||
3.4 Z4B Operating Experience Z4B material was first irradiated in test programs beginning in 1995. Z4B fuel channels have been used on a large number of fuel assemblies irradiated in different BWRs since 2009, in both RXA and BQ variants. These BWRs cover the range of all lattice types. In 2009, several Z4B BQ fuel channels on ATRIUM 10XP fuel assemblies were inserted in a German BWR that has demanding corrosion conditions. Some of these fuel channels reached their end of life in 2016 and the remaining fuel channels reached end of life in 2017 without any operational issues. | |||
These fuel channels have performed well and displayed very low growth. Bulge and bow of these fuel channels are also low. | |||
Post-irradiation examination (PIE) measurements show the corrosion performance of these fuel channels is better than that of Zr-4 fuel channels. Also, in 2009, Z4B RXA fuel channels on ATRIUM 10A fuel assemblies were inserted in a U.S. BWR that has demanding corrosion conditions. PIE campaigns were held after each biennial cycle. The last of these fuel channels were discharged in 2015 without any operational issues. These fuel channels have performed well and have displayed low growth. Bulge and bow of these fuel channels are also low. Hot cell examinations of coupons harvested from some of these fuel channels showed lower hydrogen uptake and lower average oxide thickness for a Z4B RXA fuel channel relative to a co-resident Zry-4 fuel channel. | |||
In 2012, Z4B RXA fuel channels on ATRIUM 11 lead fuel assemblies were inserted in a German BWR that has demanding corrosion conditions. These fuel channels are planned to complete six annual cycles of irradiation before being discharged. PIE campaigns were held after each of five annual cycles comparable to U.S. end of life burnups. These fuel channels have performed well and have displayed low growth. Bulge and bow of these fuel channels are also low. | |||
In 2013, Z4B RXA fuel channels on ATRIUM 11 lead fuel assemblies were inserted in a Swiss BWR. PIE inspections of visual condition and fuel channel length were performed after each of four annual cycles. These fuel channels have performed well and have displayed low growth. | |||
In 2014, Z4B BQ fuel channels were inserted on ATRIUM 10XM fuel assemblies in a U.S. BWR. | |||
Four of these Z4B BQ fuel channels were discharged in 2018 after their second biennial cycle. | |||
Fifteen of the remaining 16 fuel channels are planned to complete a third cycle in 2020. The remaining fuel channel is expected to be discharged in 2022 or 2024. | |||
Also, in 2014, Z4B BQ fuel channels on ATRIUM 11 lead fuel assemblies were inserted in a Finnish BWR. PIE examinations of visual condition and fuel channel length were conducted after each of three annual cycles. These fuel channels have performed well and have displayed low growth. A PIE campaign after the fourth annual cycle is planned to include fuel channel dimensional measurements. | |||
In 2015, Z4B BQ fuel channels on ATRIUM 11 lead fuel assemblies were inserted between two different U.S. BWRs. These lead fuel assemblies completed their first biennial cycle in late 2017. No operational issues were encountered for the fuel channels exposed for one biennial cycle. Visual inspections of two Z4B BQ fuel channels after one biennial cycle showed the fuel channels were in good condition. A PIE campaign after the second biennial cycle is planned to include fuel channel dimensional measurements. | |||
Additionally, reload batches of Z4B RXA fuel channels have been delivered to a Finnish BWR in 2016 and 2017 with continuing deliveries planned, including ATRIUM 11 reloads of Z4B BQ fuel channels in 2018 and 2019. Z4B RXA fuel channels on ATRIUM 10XM fuel assemblies have completed one and one-half annual cycles and Z4B RXA fuel channels on ATRIUM 10XM fuel assemblies have completed one half of an annual cycle. | |||
In 2018, Z4B BQ fuel channels on ATRIUM 10XM fuel assemblies started operation in a U.S. | |||
BWR. | |||
Results from these lead programs have and will provide assurance of safe operation for reload quantities of Z4B fuel channels or, in the case of unsatisfactory performance trends, allow for remediating measures (e.g., modified core loading or rechanneling) to be taken before any safety issues arise. | |||
3.5 Z4B Performance Evaluation Framatome has requested use of Z4B material on existing approved Framatome channel designs. | |||
Existing approved mechanical design requirements and calculational methods will be used to confirm the performance of Framatome channels manufactured with Z4B material. The NRC staff finds the continued use of these design requirements and methods, along with the material properties described in Section 3.3, acceptable for Z4B channels. | |||
Operating experience has shown that channel distortion and associated control blade interference has been a major problem in the U.S. BWR commercial fleet. The goal of introducing Z4B channel material is to resolve this issue. Contributing factors for channel distortion include (1) creep bulge, (2) fluence gradient-induced bow, and (3) shadow corrosion-induced bow. Each will be addressed below. | |||
Creep Bulge: | |||
Creep bulge in channels occurs because of the differential pressure between the inside and outside of the bundle. At a given axial position, the pressure drop is effectively a constant stress on the channel face that induces an elastic bulge that over time results in permanent strain. Channel deformation due to creep bulge has not been a major concern in the industry and, by itself, has not led to control blade interference issues. The purpose of this review is to provide reasonable assurance that the use of Z4B does not exacerbate creep bulge and/or introduce a new problem. Based upon the measured creep data, the NRC staff finds Z4B channel performance with respect to creep bulge acceptable. | |||
Fluence Gradient-Induced Bow: | |||
Irradiation growth is mainly attributed to the anisotropic redistribution of irradiation-induced vacancies and interstitials into dislocation loops on preferred crystallographic planes. Channel bowing occurs when a flux gradient across the channel box induces differential growth on opposite faces of the channel box. In bundles located toward the core periphery, a higher neutron flux would be experienced on the channel face toward the core interior, relative to the face toward the core periphery. Channel deformation due to fluence gradient-induced bow has been a major concern in the industry and, coupled with shadow corrosion-induced bow, has resulted in control blade interference issues. The purpose of this review is to provide reasonable assurance that Z4B channels provide improved or equivalent performance or, at least, do not exacerbate fluence gradient-induced bow and/or introduce a new problem. | |||
The database supporting the fluence gradient-induced bow performance and model is sufficient to provide a basis for determination. As described in Section 3.4, ongoing and future Z4B LUC programs are expected to provide an additional amount of new data to confirm performance and validate models although it is not a condition of this SE that Framatome must gather future data. | |||
Based upon the irradiation growth database the NRC staff finds Zr-4 fluence gradient-induced bow performance and models acceptable to be applied to Z4B. Revisions to the bow model based upon future data collection are allowed under the provisions described in Section 5. | |||
Shadow Corrosion-Induced Bow: | |||
Shadow corrosion is an enhanced irradiation corrosion mechanism that occurs on zirconium alloys when a dissimilar material (such as a stainless steel control blade) is near the zirconium surface (such as a BWR channel) and the water chemistry is oxygenated. When a fuel bundle is controlled early in life, the increased corrosion on the blade side relative to the non-blade side results in a difference in hydrogen absorbed in channel material. Hydrogen is absorbed into the metal as part of the corrosion process and causes a volume change resulting in channel bow. | |||
Because direct measurement of shadow corrosion-induced bow is only possible when the fluence gradient is zero, shadow bow is generally observed by accounting for the fluence gradient induced bow. After accounting for fluence bow in the data, the end of life channel bow correlates well with the Effective Full Insertion Days (EFID) for previous channel materials. | |||
Framatomes results for Z4B RXA and BQ show little to no correlation to EFID. | |||
The NRC staff agrees that Z4B material is a very effective fix to shadow corrosion bow and application of the existing methods to Z4B is very conservative and, therefore, acceptable. | |||
Z4B Corrosion: | |||
As with any in-reactor material the first and foremost performance requirement is that the material withstands corrosion to the extent that it maintains structural integrity, and thus, maintains its ability to perform its design requirements. For channels, maintaining structural integrity is the only corrosion performance requirement, which in practice means that the component must maintain a minimum thickness of metal. | |||
The chemical composition of Z4B targets a reduction in corrosion and hydrogen uptake with respect to Zry-4. The optional BQ heat treatment does not significantly affect corrosion or hydrogen uptake. Framatomes corrosion program consists of irradiated Z4B spacer grid hot | |||
cell exams, irradiated Z4B fuel channel hot cell exams, and pool-side eddy-current generalized oxide thickness measurements. In all cases, the corrosion performance of Z4B was superior to that of Zr-4 material. Based upon the information presented in the topical report (TR), the NRC staff finds the corrosion performance of Z4B acceptable and application of the existing approved Zr-4 models to Z4B also acceptable. | |||
Revisions to the corrosion models based upon future data collection are allowed under the provisions described in Section 5. | |||
Calculating CPR with Z4B Channels: | |||
There is no change to the SA methodology proposed in this TR. The existing methodology for calculating fuel bundle critical power ratio are fully applicable to Z4B material channels as currently approved. | |||
Other Considerations: | |||
Framatome has stated Existing BWR fuel channel distortion/control blade friction counter measures and fuel channel management guidelines for cores containing Z4B BQ fuel channels will continue to be applied until a full core of Z4B BQ fuel channels has experienced no observations of control blade-to-channel interference (e.g., slow to settle, no settle, delayed scram) for 3 consecutive years within a C- or S-Lattice design. The NRC staff finds that this is a good practice but is not a requirement for the approval of this TR. | |||
The NRC staff also concludes that licensee technical specification (TS) surveillance programs for scram time testing and reactor protection system (RPS) slow-to-settle detection are sufficient to provide future assurance that the health and safety of public will be fully maintained in the event of future fuel channel operational challenges. | |||
3.6 Range of Applicability The fully RXA and BQ Z4B alloy channel material is approved for batch application to BWR channel designs based on currently approved design methodologies (Refs. 7 and 8). | |||
The fully RXA and BQ Z4B alloy channel material is approved for batch application to BWR Type 2 (BWR/2), Type 3 (BWR/3), Type 4 (BWR/4), Type 5 (BWR/5), and Type 6 (BWR/6) designs. | |||
The lifetime of Z4B channels is restricted to the same limitations as outlined for Framatomes existing channel designs as described in Reference 3. Any fuel channel projected to exceed any of these limitations during the upcoming reload cycle shall not be loaded into the reactor, except as allowed in accordance with Framatomes approved lead use program (Ref. 6) to obtain high burnup data. | |||
==4.0 CONCLUSION== | |||
By letter dated July 25, 2018 (Ref. 1), Framatome requested review and approval of an advanced zirconium alloy, Z4B, for application to existing BWR fuel channel designs. Recent operating experience has shown that channel distortion and associated control blade interference has been a major problem in the U.S. BWR commercial fleet. The goal of introducing Z4B channel material is to resolve this issue. | |||
In 2017, the NRC staff approved Framatomes expanded LUC program for the Z4B zirconium alloy (Ref. 4). The purpose of the expanded LUC program was to allow greater numbers of Z4B channels to be exposed to varying in-reactor operating strategies, nuclear conditions, and water chemistry, in order to gain experience and gather data for batch application. The data being collected in the Z4B expanded LUC program provides confirmation of Z4B channel performance and data to validate performance models. | |||
The NRC staff has completed its review of EMF-93-177 Revision 1, Supplement 2P, Revision 1 and finds it acceptable. Licensees referencing EMF-93-177 Revision 1, Supplement 2P, Revision 1, will need to comply with the conditions listed in Section 5.0 below. | |||
With regard to the use of Z4B channels, the NRC staff has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the commissions regulations, and (3) issuance of this SE will not be inimical to the common defense and security or to the health and safety of the public. | |||
5.0 LIMITATIONS AND CONDITIONS Licensees referencing EMF-93-177 Revision 1, Supplement 2P, Revision 1 must ensure compliance with the following L&Cs: | |||
: 1. The range of applicability of Z4B channels is limited to those items described in Section 3.6 of this SE. | |||
EMF-93-177 provides sufficient information to support the use of BWR fuel assembly channels using Z4B material in batch quantities. The TR demonstrates that the previously approved fuel assembly channel models for Zr-4 are either applicable to, or conservative to, channels using Z4B material. The TR provides adequate information to demonstrate that Z4B channels are not expected to experience abnormal channel bow. Therefore, the L&Cs in the NRC approved TR ANP-10336P-A do not need to be complied with for fuel channels using Z4B material inserted in accordance with the Fuel Channel Irradiation Program. | |||
A disposition for each L&C in the SE for ANP-10336P-A (Ref. 4) is provided below. | |||
: 1. Z4B lead use channels may be used in quantities up to 8 percent of the total number of channels in the core. This limit is exclusive of other lead assembly programs. The NRC has approved this expanded LUC program in order to acquire data which may demonstrate Z4B fuel channels have improved resistance to fuel channel distortion. | |||
Since EMF-93-177 demonstrates that Z4B channels have improved resistance to fuel channel distortion and the use of Z4B channels in batch quantities is approved, the | |||
restriction to 8 percent of the total number of channels in the core is no longer applicable. | |||
: 2. The supplemental surveillance plan, described in Section 2.1 of the TR, must be fulfilled. | |||
Since EMF-93-177 demonstrates that Z4B channels have improved resistance to fuel channel distortion and the use of Z4B channels in batch quantities is approved the requirement to perform additional surveillance is no longer applicable to channels loaded under the LUC program. | |||
: 3. Channel growth, bulge, and bow measurements from at least 10 percent of the Z4B channels irradiated under the expanded LUC program must be collected following the second cycle of operation. Upon discharge, this data must be collected from at least 50 percent of the Z4B LUCs. This requirement is void upon batch approval of Z4B channels. | |||
This requirement is eliminated for the Fuel Channel Irradiation Program with the approval of Z4B channels for batch quantities. | |||
: 4. Upon availability, all data collected will be added to AREVA's database and compared with Zircaloy-4 predictive models. | |||
This requirement is eliminated for the Fuel Channel Irradiation Program with the approval of Z4B channels for batch quantities. This restriction is unnecessary since this is the common practice. | |||
: 5. As further in-reactor experience and measurements are collected, AREVA will continue to demonstrate that Z4B LUCs satisfy design requirements for each reload cycle. | |||
This requirement is eliminated with the approval of Z4B channels for batch quantities. | |||
This restriction is unnecessary since this is a design requirement. | |||
: 6. To assure continued in-reactor performance of the LUCs with regard to unanticipated channel distortion, AREVA must provide an annual report, documenting the ongoing experience with the enhanced LUC program, including any anomalous indications identified in the supplemental surveillance plan, and provide an updated database of post-irradiation measurements. | |||
Since EMF-93-177 demonstrates that Z4B channels have improved resistance to fuel channel distortion and the use of Z4B channels in batch quantities is approved, the requirement to provide an annual report for the Fuel Channel Irradiation Program is no longer applicable. The experience with Z4B channels will continue to be addressed in the annual fuel performance meetings between the NRC and Framatome. | |||
: 7. Existing BWR channel distortion - control blade interference counter measures, including fuel management guidelines and augmented monitoring and inspection programs will continue to be applied for cores containing Z4B channels. | |||
This requirement is proposed to be superseded by the requirement in Section 7 of the TR which states: | |||
Existing BWR fuel channel distortion / control blade friction counter measures and fuel | |||
channel management guidelines for cores containing Z4B RXA fuel channels will continue to be applied until a full core of Z4B RXA fuel channels has experienced no observations of control blade-to-channel interference (e.g., slow to settle, no settle, delayed scram) for 3 consecutive years within a C- or S-Lattice design. | |||
This requirement is in Section 7.1 for RXA and is repeated in Section 7.2 for BQ. | |||
Although the NRC staff finds that this is a good practice, it is not a requirement for the approval of this TR and therefore not a L&C. | |||
The NRC staff also concludes that licensees TS surveillance programs for scram time testing and RPS slow-to-settle detection are sufficient to provide future assurance that the health and safety of the public will be fully maintained in the event of future fuel channel operational challenges. | |||
TR Updates: | |||
With respect to modification to Z4B composition, heat treatments, and changes to the mechanical designs of Framatomes BWR channels, those changes may be implemented without further NRC review and approval as long as the following criterion are met: | |||
* Improved limits may be credited in the future as long as Framatome uses the methodology previously used to provide the basis for its existing channel irradiation limits. This is to say that incorporating additional PIE measurement data into the operating experience database may be credited for use in less restrictive limits as long as the same approved analytical methods are used to derive the new limits. Use of unapproved statistical methods would require NRC review and approval. | |||
* New mechanical designs may be implemented under the LUC program and subsequent batch application as long as there are no approved analysis methodology deviations. | |||
* New zirconium based channel materials may be implemented under the LUC program and subsequent batch application as long as there are no approved analysis methodology deviations. | |||
==6.0 REFERENCES== | |||
: 1. EMF-93-177 Revision 1 Supplement 2P Revision 1, Mechanical Design for BWR Fuel Channels: Z4B Material, July 2018 (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML18211A318). | |||
: 2. EMF-93-177(P)(A), Revision 1, Mechanical Design for BWR Fuel Channels, Framatome ANP, August 2005 (ADAMS Accession No. ML052370370). | |||
: 3. EMF-93-177 (P)(A), Revision 1, Supplement 1 P-A, Revision 0, Mechanical Design for BWR Fuel Channels Supplement 1: Advanced Methods for New Channel Designs, AREVA NP, September 2013 (ADAMS Accession No. ML18211A309 (Non-publicly available)). | |||
: 4. ANP-10336P-A, Revision 0, Z4B Fuel Channel Irradiation Program July 2017 (ADAMS Accession No. ML17298A159). | |||
: 5. NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, Section 4.2, Fuel System Design, Revision 3, March 2007 (ADAMS Accession No. ML070740002). | |||
: 6. ANP-10336P, Revision 0, Z4B Fuel Channel Irradiation Program June 2015 (ADAMS Package Accession No. ML15188A230). | |||
: 7. BAW-10247PA, Revision 0, Realistic Thermal-Mechanical Fuel Rod Methodology for Boiling Water Reactors, AREVA NP, April 2008. | |||
: 8. ANP-10307PA, Revision 0, AREVA MCPR Safety Limit Methodology for Boiling Water Reactors, AREVA NP, June 2011. | |||
==Attachment:== | |||
Resolution of Comments Principal Contributor: J. Dean, NRR/DSS/SNPB Date: June 24, 2019}} |
Latest revision as of 18:28, 19 October 2019
ML19149A486 | |
Person / Time | |
---|---|
Site: | PROJ0728, 99902041 |
Issue date: | 06/24/2019 |
From: | Jeremy Dean NRC/NRR/DSS/SNPB |
To: | Peters G Framatome |
Rowley J, NRR/DLP, 415-4053 | |
Shared Package | |
ML19149A479 -Pkg. | List: |
References | |
EPID L-2018-TOP-0029 EMF-93-177 | |
Download: ML19149A486 (11) | |
Text
FINAL SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION TOPICAL REPORT EMF-93-177, REVISION 1, SUPPLEMENT 2P, REVISION 1 MECHANICAL DESIGN FOR BWR FUEL CHANNELS: Z4B MATERIAL FRAMATOME INC.
PROJECT NO. 728/DOCKET NO. 99902041
1.0 INTRODUCTION
By letter dated July 25, 2018 (Ref. 1), Framatome Inc. (Framatome) requested review and approval of an advanced zirconium (Zr) alloy, Z4B, for batch application to existing boiling water reactor (BWR) fuel channel designs. Framatome developed Z4B to address excessive control blade friction due to abnormal fuel channel bow and bulge primarily caused by hydrogen-assisted accelerated irradiation-induced differential growth, galvanic style shadow corrosion from low exposure control blade insertion, and channel deformation/creep from differential pressure, that was experienced by the nuclear power industry when it transitioned to Zr-2 based fuel channel materials and thick-thin channel mechanical designs in the 2000s.
Z4B is a Zr-4 based material with increased alloying elements of iron (Fe) and chromium (Cr). It is manufactured with one of two heat options, either fully recrystallized annealed (RXA) or beta-quenched (BQ).
In 2017, the U.S. Nuclear Regulatory Commission (NRC) staff approved Framatomes expanded lead use channel (LUC) program for the Z4B zirconium alloy (Ref. 4). The purpose of the expanded LUC program was to allow greater numbers of channels to be exposed to varying in-reactor operating strategies, nuclear conditions, and water chemistry in order to gain experience and gather data for batch application. Reference 4 describes the LUC program and Reference 1 summarizes the results of the LUC program. Section 5.0 of this safety evaluation (SE) addresses the limitations and conditions (L&Cs) imposed on the use of Z4B channels by Reference 4 during the LUC program and any new L&Cs as a result of this review.
It is important to note that Framatome is not requesting any new performance models for the Z4B material, even though it has improved characteristics. Nor is Framatome requesting any changes to the methodology used in a licensees safety analyses (SAs) evaluation models (EMs) for licensing Framatomes fuel products. Reference 1 justifies the existing Zr-4 based performance models (Refs. 2 and 3) and their application within a licensees SA methods is applicable and conservative for use with Z4B.
EMF-93-177, Revision 1, Supplement 2P, Revision 1, Mechanical Design for BWR Fuel Channels: Z4B Material, will be referred to as EMF-93-177 in the remainder of this SE.
Enclosure
2.0 REGULATORY EVALUATION
Regulatory guidance for the review of fuel system materials and designs and adherence to General Design Criteria (GDC)-10, GDC-27, and GDC-35 is provided in NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants (SRP), Section 4.2, Fuel System Design (Ref. 5). In accordance with SRP Section 4.2, the objectives of the fuel system safety review are to provide assurance that:
- The fuel system is not damaged as a result of normal operation and anticipated operational occurrences (AOOs).
- Fuel system damage is never so severe as to prevent control rod insertion when it is required.
- The number of fuel rod failures is not underestimated for postulated accidents, and coolability is always maintained.
The main focus of the limited SRP guidance with respect to BWR fuel bundle channels is control blade interference and insertability. SRP Section 4.2.II.1.A.v states:
Control blade/rod, channel, and guide tube bow as a result of (1) differential irradiation growth (from fluence gradients), (2) shadow corrosion (hydrogen uptake results in swelling), and (3) stress relaxation, which can impact control blade/rod insertability from interference problems between these components. For BWRs, the effects of shadow corrosion should be considered for new control blade or channel designs, dimensions (e.g., the distance between control blade and channel is important), or materials. The effects of channel bulge should also be considered for interference problems for BWRs.
Design changes can alter the pressure drop across the channel wall, thus necessitating an evaluation of such changes. Channel material changes can also impact the differential growth, stress relaxation, and the amount of bulge and therefore must be evaluated. If interference is determined to be possible, tests are needed to demonstrate control blade/rod insertability consistent with assumptions in safety analyses. Additional in-reactor surveillance (e.g., insertion times) may also be necessary for new designs, dimensions, and materials to demonstrate satisfactory performance.
With respect to ensuring control blade insertability under externally applied loads (i.e., safe shutdown earthquake and loss-of-coolant accident), SRP 4.2 Appendix A,Section IV states:
For a BWR, several conditions must be met to demonstrate control blade insertability
- (1) combined loads on the channel box must remain below the allowable value defined above for components other than grids (otherwise, additional analysis is needed to show that the deformation is not severe enough to prevent control blade insertion) and (2) vertical liftoff forces must not unseat the lower tieplate from the fuel support piece such that the resulting loss of lateral fuel bundle positioning could interfere with control blade insertion.
The NRC staffs review of EMF-93-177 is to ensure that the introduction of Z4B does not adversely impact the ability of existing BWR channel designs to satisfy these requirements.
3.0 TECHNICAL EVALUATION
The NRC staffs review of the EMF-93-177 is summarized below:
- Verify that the fuel channel design requirements are consistent with regulatory criteria identified in SRP 4.2 or are otherwise acceptable and justified.
- Verify that the Z4B channel design satisfies regulatory requirements.
- Verify that the Framatome experience database (in-reactor residence, post-irradiation examinations, and out-of-pile testing) supports the operating limits being requested and provides reasonable assurance that no anomalous behavior will occur during batch implementation.
- Verify that the impact of the Framatome channel designs on the reload design methodology, safety analyses, and setpoints has been properly addressed.
- Define the range of applicability and allowed manufacturing tolerances/variances (e.g., alloy composition, microstructure).
- Define future surveillance and reporting requirements as necessary. The NRC staffs review builds upon the Z4B enhanced LUC program (Ref. 4) and the operating experience and data collected from past and ongoing surveillance programs.
3.1 BWR Channel Design Requirements The design requirements for Framatomes BWR channels are described in References 2 and 3 and are unchanged for Z4B materials and heat treatments. These design requirements have been previously approved and are consistent with the SRP and, therefore, remain acceptable.
3.2 Z4B Composition and Microstructure The composition of Z4B is similar to that of Zry-4 as defined in ASTM B352/B352M, with the exceptions that Z4B has slightly higher Fe and Cr contents. The exact material contents are proprietary and will not be restated here. Zry-4 was developed based on Zry-2 with the intent to remove Ni from the alloy and avoid the high hydrogen pickup which is seen in Zry-2 which is thought to be a primary driver of irradiation growth in zirconium materials. Z4B and the Zircaloys are composed of about 98 weight percent zirconium and have a hexagonal crystal structure at room and service temperatures. Z4B also has improved corrosion resistance that may be necessary for some licensees challenging reactor chemistry environments.
Framatome's Z4B is made in either the RXA or BQ final microstructure. The BQ process results in a quasi-isotropic texture that has demonstrated the ability to reduce the irradiation growth rate of Zircaloys.
3.3 Z4B Material Properties The unirradiated Z4B properties (melting point, density, heat capacity, thermal conductivity, and thermal expansion) are nearly identical to those of Zr-4 which is fully expected. The slight increase of Fe and Cr in Z4B has an insignificant effect on parameters impacting elastic properties including Young's modulus, and Poisson's ratio. These parameters include bond length, coordination number, and charge of the metal ion. It is therefore acceptable to apply the existing Zr-4 based properties to Z4B.
3.4 Z4B Operating Experience Z4B material was first irradiated in test programs beginning in 1995. Z4B fuel channels have been used on a large number of fuel assemblies irradiated in different BWRs since 2009, in both RXA and BQ variants. These BWRs cover the range of all lattice types. In 2009, several Z4B BQ fuel channels on ATRIUM 10XP fuel assemblies were inserted in a German BWR that has demanding corrosion conditions. Some of these fuel channels reached their end of life in 2016 and the remaining fuel channels reached end of life in 2017 without any operational issues.
These fuel channels have performed well and displayed very low growth. Bulge and bow of these fuel channels are also low.
Post-irradiation examination (PIE) measurements show the corrosion performance of these fuel channels is better than that of Zr-4 fuel channels. Also, in 2009, Z4B RXA fuel channels on ATRIUM 10A fuel assemblies were inserted in a U.S. BWR that has demanding corrosion conditions. PIE campaigns were held after each biennial cycle. The last of these fuel channels were discharged in 2015 without any operational issues. These fuel channels have performed well and have displayed low growth. Bulge and bow of these fuel channels are also low. Hot cell examinations of coupons harvested from some of these fuel channels showed lower hydrogen uptake and lower average oxide thickness for a Z4B RXA fuel channel relative to a co-resident Zry-4 fuel channel.
In 2012, Z4B RXA fuel channels on ATRIUM 11 lead fuel assemblies were inserted in a German BWR that has demanding corrosion conditions. These fuel channels are planned to complete six annual cycles of irradiation before being discharged. PIE campaigns were held after each of five annual cycles comparable to U.S. end of life burnups. These fuel channels have performed well and have displayed low growth. Bulge and bow of these fuel channels are also low.
In 2013, Z4B RXA fuel channels on ATRIUM 11 lead fuel assemblies were inserted in a Swiss BWR. PIE inspections of visual condition and fuel channel length were performed after each of four annual cycles. These fuel channels have performed well and have displayed low growth.
In 2014, Z4B BQ fuel channels were inserted on ATRIUM 10XM fuel assemblies in a U.S. BWR.
Four of these Z4B BQ fuel channels were discharged in 2018 after their second biennial cycle.
Fifteen of the remaining 16 fuel channels are planned to complete a third cycle in 2020. The remaining fuel channel is expected to be discharged in 2022 or 2024.
Also, in 2014, Z4B BQ fuel channels on ATRIUM 11 lead fuel assemblies were inserted in a Finnish BWR. PIE examinations of visual condition and fuel channel length were conducted after each of three annual cycles. These fuel channels have performed well and have displayed low growth. A PIE campaign after the fourth annual cycle is planned to include fuel channel dimensional measurements.
In 2015, Z4B BQ fuel channels on ATRIUM 11 lead fuel assemblies were inserted between two different U.S. BWRs. These lead fuel assemblies completed their first biennial cycle in late 2017. No operational issues were encountered for the fuel channels exposed for one biennial cycle. Visual inspections of two Z4B BQ fuel channels after one biennial cycle showed the fuel channels were in good condition. A PIE campaign after the second biennial cycle is planned to include fuel channel dimensional measurements.
Additionally, reload batches of Z4B RXA fuel channels have been delivered to a Finnish BWR in 2016 and 2017 with continuing deliveries planned, including ATRIUM 11 reloads of Z4B BQ fuel channels in 2018 and 2019. Z4B RXA fuel channels on ATRIUM 10XM fuel assemblies have completed one and one-half annual cycles and Z4B RXA fuel channels on ATRIUM 10XM fuel assemblies have completed one half of an annual cycle.
In 2018, Z4B BQ fuel channels on ATRIUM 10XM fuel assemblies started operation in a U.S.
BWR.
Results from these lead programs have and will provide assurance of safe operation for reload quantities of Z4B fuel channels or, in the case of unsatisfactory performance trends, allow for remediating measures (e.g., modified core loading or rechanneling) to be taken before any safety issues arise.
3.5 Z4B Performance Evaluation Framatome has requested use of Z4B material on existing approved Framatome channel designs.
Existing approved mechanical design requirements and calculational methods will be used to confirm the performance of Framatome channels manufactured with Z4B material. The NRC staff finds the continued use of these design requirements and methods, along with the material properties described in Section 3.3, acceptable for Z4B channels.
Operating experience has shown that channel distortion and associated control blade interference has been a major problem in the U.S. BWR commercial fleet. The goal of introducing Z4B channel material is to resolve this issue. Contributing factors for channel distortion include (1) creep bulge, (2) fluence gradient-induced bow, and (3) shadow corrosion-induced bow. Each will be addressed below.
Creep Bulge:
Creep bulge in channels occurs because of the differential pressure between the inside and outside of the bundle. At a given axial position, the pressure drop is effectively a constant stress on the channel face that induces an elastic bulge that over time results in permanent strain. Channel deformation due to creep bulge has not been a major concern in the industry and, by itself, has not led to control blade interference issues. The purpose of this review is to provide reasonable assurance that the use of Z4B does not exacerbate creep bulge and/or introduce a new problem. Based upon the measured creep data, the NRC staff finds Z4B channel performance with respect to creep bulge acceptable.
Fluence Gradient-Induced Bow:
Irradiation growth is mainly attributed to the anisotropic redistribution of irradiation-induced vacancies and interstitials into dislocation loops on preferred crystallographic planes. Channel bowing occurs when a flux gradient across the channel box induces differential growth on opposite faces of the channel box. In bundles located toward the core periphery, a higher neutron flux would be experienced on the channel face toward the core interior, relative to the face toward the core periphery. Channel deformation due to fluence gradient-induced bow has been a major concern in the industry and, coupled with shadow corrosion-induced bow, has resulted in control blade interference issues. The purpose of this review is to provide reasonable assurance that Z4B channels provide improved or equivalent performance or, at least, do not exacerbate fluence gradient-induced bow and/or introduce a new problem.
The database supporting the fluence gradient-induced bow performance and model is sufficient to provide a basis for determination. As described in Section 3.4, ongoing and future Z4B LUC programs are expected to provide an additional amount of new data to confirm performance and validate models although it is not a condition of this SE that Framatome must gather future data.
Based upon the irradiation growth database the NRC staff finds Zr-4 fluence gradient-induced bow performance and models acceptable to be applied to Z4B. Revisions to the bow model based upon future data collection are allowed under the provisions described in Section 5.
Shadow Corrosion-Induced Bow:
Shadow corrosion is an enhanced irradiation corrosion mechanism that occurs on zirconium alloys when a dissimilar material (such as a stainless steel control blade) is near the zirconium surface (such as a BWR channel) and the water chemistry is oxygenated. When a fuel bundle is controlled early in life, the increased corrosion on the blade side relative to the non-blade side results in a difference in hydrogen absorbed in channel material. Hydrogen is absorbed into the metal as part of the corrosion process and causes a volume change resulting in channel bow.
Because direct measurement of shadow corrosion-induced bow is only possible when the fluence gradient is zero, shadow bow is generally observed by accounting for the fluence gradient induced bow. After accounting for fluence bow in the data, the end of life channel bow correlates well with the Effective Full Insertion Days (EFID) for previous channel materials.
Framatomes results for Z4B RXA and BQ show little to no correlation to EFID.
The NRC staff agrees that Z4B material is a very effective fix to shadow corrosion bow and application of the existing methods to Z4B is very conservative and, therefore, acceptable.
Z4B Corrosion:
As with any in-reactor material the first and foremost performance requirement is that the material withstands corrosion to the extent that it maintains structural integrity, and thus, maintains its ability to perform its design requirements. For channels, maintaining structural integrity is the only corrosion performance requirement, which in practice means that the component must maintain a minimum thickness of metal.
The chemical composition of Z4B targets a reduction in corrosion and hydrogen uptake with respect to Zry-4. The optional BQ heat treatment does not significantly affect corrosion or hydrogen uptake. Framatomes corrosion program consists of irradiated Z4B spacer grid hot
cell exams, irradiated Z4B fuel channel hot cell exams, and pool-side eddy-current generalized oxide thickness measurements. In all cases, the corrosion performance of Z4B was superior to that of Zr-4 material. Based upon the information presented in the topical report (TR), the NRC staff finds the corrosion performance of Z4B acceptable and application of the existing approved Zr-4 models to Z4B also acceptable.
Revisions to the corrosion models based upon future data collection are allowed under the provisions described in Section 5.
Calculating CPR with Z4B Channels:
There is no change to the SA methodology proposed in this TR. The existing methodology for calculating fuel bundle critical power ratio are fully applicable to Z4B material channels as currently approved.
Other Considerations:
Framatome has stated Existing BWR fuel channel distortion/control blade friction counter measures and fuel channel management guidelines for cores containing Z4B BQ fuel channels will continue to be applied until a full core of Z4B BQ fuel channels has experienced no observations of control blade-to-channel interference (e.g., slow to settle, no settle, delayed scram) for 3 consecutive years within a C- or S-Lattice design. The NRC staff finds that this is a good practice but is not a requirement for the approval of this TR.
The NRC staff also concludes that licensee technical specification (TS) surveillance programs for scram time testing and reactor protection system (RPS) slow-to-settle detection are sufficient to provide future assurance that the health and safety of public will be fully maintained in the event of future fuel channel operational challenges.
3.6 Range of Applicability The fully RXA and BQ Z4B alloy channel material is approved for batch application to BWR channel designs based on currently approved design methodologies (Refs. 7 and 8).
The fully RXA and BQ Z4B alloy channel material is approved for batch application to BWR Type 2 (BWR/2), Type 3 (BWR/3), Type 4 (BWR/4), Type 5 (BWR/5), and Type 6 (BWR/6) designs.
The lifetime of Z4B channels is restricted to the same limitations as outlined for Framatomes existing channel designs as described in Reference 3. Any fuel channel projected to exceed any of these limitations during the upcoming reload cycle shall not be loaded into the reactor, except as allowed in accordance with Framatomes approved lead use program (Ref. 6) to obtain high burnup data.
4.0 CONCLUSION
By letter dated July 25, 2018 (Ref. 1), Framatome requested review and approval of an advanced zirconium alloy, Z4B, for application to existing BWR fuel channel designs. Recent operating experience has shown that channel distortion and associated control blade interference has been a major problem in the U.S. BWR commercial fleet. The goal of introducing Z4B channel material is to resolve this issue.
In 2017, the NRC staff approved Framatomes expanded LUC program for the Z4B zirconium alloy (Ref. 4). The purpose of the expanded LUC program was to allow greater numbers of Z4B channels to be exposed to varying in-reactor operating strategies, nuclear conditions, and water chemistry, in order to gain experience and gather data for batch application. The data being collected in the Z4B expanded LUC program provides confirmation of Z4B channel performance and data to validate performance models.
The NRC staff has completed its review of EMF-93-177 Revision 1, Supplement 2P, Revision 1 and finds it acceptable. Licensees referencing EMF-93-177 Revision 1, Supplement 2P, Revision 1, will need to comply with the conditions listed in Section 5.0 below.
With regard to the use of Z4B channels, the NRC staff has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the commissions regulations, and (3) issuance of this SE will not be inimical to the common defense and security or to the health and safety of the public.
5.0 LIMITATIONS AND CONDITIONS Licensees referencing EMF-93-177 Revision 1, Supplement 2P, Revision 1 must ensure compliance with the following L&Cs:
- 1. The range of applicability of Z4B channels is limited to those items described in Section 3.6 of this SE.
EMF-93-177 provides sufficient information to support the use of BWR fuel assembly channels using Z4B material in batch quantities. The TR demonstrates that the previously approved fuel assembly channel models for Zr-4 are either applicable to, or conservative to, channels using Z4B material. The TR provides adequate information to demonstrate that Z4B channels are not expected to experience abnormal channel bow. Therefore, the L&Cs in the NRC approved TR ANP-10336P-A do not need to be complied with for fuel channels using Z4B material inserted in accordance with the Fuel Channel Irradiation Program.
A disposition for each L&C in the SE for ANP-10336P-A (Ref. 4) is provided below.
- 1. Z4B lead use channels may be used in quantities up to 8 percent of the total number of channels in the core. This limit is exclusive of other lead assembly programs. The NRC has approved this expanded LUC program in order to acquire data which may demonstrate Z4B fuel channels have improved resistance to fuel channel distortion.
Since EMF-93-177 demonstrates that Z4B channels have improved resistance to fuel channel distortion and the use of Z4B channels in batch quantities is approved, the
restriction to 8 percent of the total number of channels in the core is no longer applicable.
- 2. The supplemental surveillance plan, described in Section 2.1 of the TR, must be fulfilled.
Since EMF-93-177 demonstrates that Z4B channels have improved resistance to fuel channel distortion and the use of Z4B channels in batch quantities is approved the requirement to perform additional surveillance is no longer applicable to channels loaded under the LUC program.
- 3. Channel growth, bulge, and bow measurements from at least 10 percent of the Z4B channels irradiated under the expanded LUC program must be collected following the second cycle of operation. Upon discharge, this data must be collected from at least 50 percent of the Z4B LUCs. This requirement is void upon batch approval of Z4B channels.
This requirement is eliminated for the Fuel Channel Irradiation Program with the approval of Z4B channels for batch quantities.
- 4. Upon availability, all data collected will be added to AREVA's database and compared with Zircaloy-4 predictive models.
This requirement is eliminated for the Fuel Channel Irradiation Program with the approval of Z4B channels for batch quantities. This restriction is unnecessary since this is the common practice.
- 5. As further in-reactor experience and measurements are collected, AREVA will continue to demonstrate that Z4B LUCs satisfy design requirements for each reload cycle.
This requirement is eliminated with the approval of Z4B channels for batch quantities.
This restriction is unnecessary since this is a design requirement.
- 6. To assure continued in-reactor performance of the LUCs with regard to unanticipated channel distortion, AREVA must provide an annual report, documenting the ongoing experience with the enhanced LUC program, including any anomalous indications identified in the supplemental surveillance plan, and provide an updated database of post-irradiation measurements.
Since EMF-93-177 demonstrates that Z4B channels have improved resistance to fuel channel distortion and the use of Z4B channels in batch quantities is approved, the requirement to provide an annual report for the Fuel Channel Irradiation Program is no longer applicable. The experience with Z4B channels will continue to be addressed in the annual fuel performance meetings between the NRC and Framatome.
- 7. Existing BWR channel distortion - control blade interference counter measures, including fuel management guidelines and augmented monitoring and inspection programs will continue to be applied for cores containing Z4B channels.
This requirement is proposed to be superseded by the requirement in Section 7 of the TR which states:
Existing BWR fuel channel distortion / control blade friction counter measures and fuel
channel management guidelines for cores containing Z4B RXA fuel channels will continue to be applied until a full core of Z4B RXA fuel channels has experienced no observations of control blade-to-channel interference (e.g., slow to settle, no settle, delayed scram) for 3 consecutive years within a C- or S-Lattice design.
This requirement is in Section 7.1 for RXA and is repeated in Section 7.2 for BQ.
Although the NRC staff finds that this is a good practice, it is not a requirement for the approval of this TR and therefore not a L&C.
The NRC staff also concludes that licensees TS surveillance programs for scram time testing and RPS slow-to-settle detection are sufficient to provide future assurance that the health and safety of the public will be fully maintained in the event of future fuel channel operational challenges.
TR Updates:
With respect to modification to Z4B composition, heat treatments, and changes to the mechanical designs of Framatomes BWR channels, those changes may be implemented without further NRC review and approval as long as the following criterion are met:
- Improved limits may be credited in the future as long as Framatome uses the methodology previously used to provide the basis for its existing channel irradiation limits. This is to say that incorporating additional PIE measurement data into the operating experience database may be credited for use in less restrictive limits as long as the same approved analytical methods are used to derive the new limits. Use of unapproved statistical methods would require NRC review and approval.
- New mechanical designs may be implemented under the LUC program and subsequent batch application as long as there are no approved analysis methodology deviations.
- New zirconium based channel materials may be implemented under the LUC program and subsequent batch application as long as there are no approved analysis methodology deviations.
6.0 REFERENCES
- 1. EMF-93-177 Revision 1 Supplement 2P Revision 1, Mechanical Design for BWR Fuel Channels: Z4B Material, July 2018 (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML18211A318).
- 2. EMF-93-177(P)(A), Revision 1, Mechanical Design for BWR Fuel Channels, Framatome ANP, August 2005 (ADAMS Accession No. ML052370370).
- 3. EMF-93-177 (P)(A), Revision 1, Supplement 1 P-A, Revision 0, Mechanical Design for BWR Fuel Channels Supplement 1: Advanced Methods for New Channel Designs, AREVA NP, September 2013 (ADAMS Accession No. ML18211A309 (Non-publicly available)).
- 4. ANP-10336P-A, Revision 0, Z4B Fuel Channel Irradiation Program July 2017 (ADAMS Accession No. ML17298A159).
- 5. NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, Section 4.2, Fuel System Design, Revision 3, March 2007 (ADAMS Accession No. ML070740002).
- 6. ANP-10336P, Revision 0, Z4B Fuel Channel Irradiation Program June 2015 (ADAMS Package Accession No. ML15188A230).
- 7. BAW-10247PA, Revision 0, Realistic Thermal-Mechanical Fuel Rod Methodology for Boiling Water Reactors, AREVA NP, April 2008.
- 8. ANP-10307PA, Revision 0, AREVA MCPR Safety Limit Methodology for Boiling Water Reactors, AREVA NP, June 2011.
Attachment:
Resolution of Comments Principal Contributor: J. Dean, NRR/DSS/SNPB Date: June 24, 2019