ML20031D699

NRC Staff Supplemental Proposed Findings of Fact and Conclusions of Law

ML20031D699
Person / Time
Site:	Seabrook
Issue date:	01/31/2020
From:	Jeremy Wachutka NRC/OGC
To:	Atomic Safety and Licensing Board Panel
SECY RAS
References
50-443-LA-2, ASLBP 17-953-02-LA-BD01, RAS 55543
Download: ML20031D699 (9)

Text

UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of NEXTERA ENERGY SEABROOK, LLC Docket No. 50-443-LA-2 (Seabrook Station, Unit 1)

NRC STAFF SUPPLEMENTAL PROPOSED FINDINGS OF FACT AND CONCLUSIONS OF LAW In accordance with 10 C.F.R. § 2.1209 and the Atomic Safety and Licensing Boards Orders of November 25, 2019 1 and January 17, 2020, 2 the NRC Staff files the following supplemental proposed findings of fact and conclusions of law 3 limited to the specific issues raised in Exhibits INT051-R, 4 NER077, 5 and NRC091. 6 The supplemental proposed findings of 1

Order (Granting C-10s Motion to Compel Mineralogical Data and Request to Submit Supplemental Written Testimony concerning the data; Denying C-10s Motion to Submit Additional Exhibits), at 17 (Nov.

25, 2019) (unpublished) (ML19329D913) (November 25, 2019 Order).

2 Order (Admitting Exhibits, Closing the Record of the September 2019 Evidentiary Hearing, and Providing Additional Instruction for Supplemental Proposed Findings), at 2 (Jan. 17, 2020) (unpublished)

(ML20017A076) (January 17, 2020 Order).

3 Consistent with the format requirements of 10 C.F.R. § 2.712(c), the supplemental proposed findings of fact and conclusions of law are set forth in numbered paragraphs with citations to the evidentiary record in this proceeding.

4 Exhibit INT051-R-00-BD01, Supplemental Testimony of Victor E. Saouma, Ph.D Regarding Adequacy of Petrographic Documents to Support Mineralogical Comparison between Seabrook Concrete and LSTP Test Specimens (Dec. 20, 2019) (ML20006E227).

5 Exhibit NER077-00-BD01, Testimony of NextEra Witnesses John Simons, Christopher Bagley, Oguzhan Bayrak, Matthew Sherman, and Edward Carley in Response to Exhibit INT051-R (Jan. 10, 2020)

(ML20010F265).

6 Exhibit NRC091-00-BD01, Staff Testimony in Response to Exhibit INT051-R (Jan. 10, 2020)

(ML20010D368).

fact and conclusions of law are presented in the form of an initial decision by the Board and use the same acronyms and short citations as defined in the NRC Staffs initial proposed findings of fact and conclusions of law. 7 I. SUPPLEMENTAL FINDINGS OF FACT A. Board Findings on (1) the Relevance of the Chemical Composition of ASR Gel to the Structural Impacts of ASR and (2) the Relevance of the LSTP to the Adequacy of the CI/CCI Methodology for ASR Expansion Monitoring at Seabrook 8 1.1 ASR is a chemical reaction in hardened concrete that produces a gel that can absorb water and expand. The expansion of the gel is resisted by internal restraints within the concrete such as those provided by rebar. This interaction between internal restraints and ASR gel expansion results in microcracking preferentially oriented in directions of least restraint and, ultimately, expansion of the affected concrete component. 9 1.2 Seabrook concrete components are required to be capable of fulfilling their intended functions under design basis loads and load combinations. 10 Specifically, safety-related structures other than containment were designed and constructed to comply with ACI 318-71 and containment was designed and constructed to comply with the ASME Code,Section III, Division 2 (together, the licensing basis codes). 11 ASR expansion degrades the material 7

See NRC Staff Proposed Findings of Fact and Conclusions of Law for the Admitted Contention (Nov.

21, 2019) (ML19325D909) (abbreviating alkali-silica reaction as ASR, Ferguson Structural Engineering Laboratory as FSEL, large-scale test program as LSTP, crack indexing/combined crack indexing as CI/CCI, snap-ring borehole extensometer as SRBE).

8 See January 17, 2020 Order at 2 (The parties should identify in their supplemental proposed findings of fact any study or other documentation in the record of this proceeding that addresses the question whether differences in the chemical composition of ASR gel may (or may not) affect either (1) the structural impacts of ASR, or (2) the adequacy of the CCI methodology for ASR expansion monitoring.).

9 Exhibit NRC091-00-BD01 at 3.

10 Exhibit NRC001-R-00-BD01, Staff Testimony at 8 (citing Exhibit NRC007-00-BD01, UFSAR § 3.8).

11 Exhibit NRC007-00-BD01, UFSAR § 3.8.

properties of concrete, 12 which, in turn, can reduce the structural capacity of a concrete component. 13 For ASR-affected reinforced concrete components, however, in-situ material properties are expected to be considerably better than material properties measured on cores that have been removed from the components. 14 Therefore, instead of relying on the material properties of cores removed from Seabrook concrete components to determine whether the components will be capable of fulfilling their intended functions, the FSEL developed the LSTP to study the overall structural properties of these components. 15 Since the available industry guidance and academic literature correlates the effect of ASR on the structural properties of concrete components with the observed expansion of the ASR-affected concrete components, 16 the LSTP studied varying levels of ASR expansion to determine whether, at these expansion levels, the structural properties of the test specimens would be affected.

1.3 To ensure that the results of the LSTP would be applicable to Seabrook concrete components, the FSEL first identified the characteristics of concrete components that are critical to their structural capacity. 17 For instance, with respect to the coarse aggregate used in the concrete mix design, the FSEL identified size and surface roughness as critical characteristics because these can both affect the aggregate interlock mechanism for developing shear strength, which, in turn, can affect a concrete components structural capacity. 18 The FSEL then 12 Exhibit NRC001-R-00-BD01, Staff Testimony at 7. The material properties of concrete include compressive strength, elastic modulus, tensile strength, shear strength, and flexural strength. Id.

13 Id. at 8.

14 Id. at 9.

15 Id. at 58.

16 See Exhibit NER077-00-BD01 at 4 (citing Exhibit NER013-00-BD01, FHWA Report at 37, tbl. 9; Exhibit NER012-00-BD01, ISE Report at §§ 6.3.2, 8.2); Tr. at 982-83.

17 Exhibit NER077-00-BD01 at 3.

18 Id.

ensured that, with respect to the identified critical characteristics, the LSTP test specimens and Seabrook concrete components matched as closely as reasonably achievable. 19 1.4 The results of the LSTP demonstrated that, within the ASR expansion levels tested, the structural properties of the test specimens were unaffected. 20 1.5 The Seabrook ASR expansion monitoring program applies the results of the LSTP to Seabrook. First, the program requires the measurement of expansion of Seabrook concrete components in the in-plane direction using the CI/CCI methodology. 21 Then, when in-plane expansion reaches a specified threshold, the program also requires the measurement of expansion in the through-thickness direction using the readings taken from an SRBE combined with a calculation of the through-thickness expansion that had occurred up to the time of the SRBEs installation. 22 These expansion measurements are combined to provide volumetric expansion. 23 The program then requires the comparison of these measurements to limits derived from the LSTP. 24 Consistent with the results of the LSTP, as long as the measurements remain below the limits derived from the LSTP, the structural properties of the concrete components will be unaffected and, therefore, their structural capacity can still be conservatively 19 Exhibit NRC091-00-BD01 at 3. C-10 expert witness Dr. Saouma agreed that [t]here is a very strong similarity in the gradation between the LSTP and Seabrook coarse aggregate, Tr. at 1074, and that the two are comparable in their physical property, Tr. at 1076.

20 Exhibit NRC001-R-00-BD01, Staff Testimony at 58.

21 Id. at 18; Exhibit INT010-00-BD01, Original LAR at 17 (unnumbered); Exhibit INT024-00-BD01, SE, encl. 2 at 9. A CI is obtained by measuring and summing the crack widths along a set of perpendicular lines on the surface of a concrete element and normalizing the sum by the length of reference lines (typically reported in mm/m). A CCI is the weighted average of the CI in the two measured directions.

Once a CI grid is set up, the same location is monitored over time and the CI values provide a quantifiable measurement of the state of cracking on the concrete component. Exhibit NRC001-R BD01, Staff Testimony at 18-19.

22 Exhibit NRC001-R-00-BD01, Staff Testimony at 18-19; Exhibit INT010-00-BD01, Original LAR at 17 (unnumbered); Exhibit INT024-00-BD01, SE, encl. 2 at 21.

23 Exhibit NRC001-R-00-BD01, Staff Testimony at 19.

24 See Exhibit INT024-00-BD01, SE, encl. 2 at 61.

estimated by the existing licensing basis codes, regardless of any reductions in concrete material properties due to ASR. 25 1.6 C-10 expert witness Dr. Saouma argued, in part, that the LSTP test specimens were not representative of Seabrook concrete components and, as a result, the expansion limits derived from the LSTP were not adequate. 26 In Exhibit INT051-R, Dr. Saouma asserted as one example of this alleged non-representativeness that NextEra has not shown that the chemical characteristics of the minerals in the aggregate used for the test specimens were the same as those used at Seabrook. 27 Specifically, Dr. Saouma identified that the [r]eactivity of the aggregate has a significant effect on the characteristics of the [ASR] gel and microcracking. 28 To support this statement, Dr. Saouma pointed to portions of his previous testimony that discuss (1) expansion rate and aggregate reactivity and (2) the adequacy of the CI/CCI methodology for ASR expansion monitoring at Seabrook. 29 1.7 NextEra expert witnesses explained that differences in chemical characteristics of aggregate could lead to different rates of reaction, different characteristics of any resulting ASR gel, and different patterns of microcracks; however, they also explained that none of these 25 See Tr. at 331 (Sherman) ([T]he whole point, remember, of this entire project, is to know where we are, and stay inside that box thats defined by the testing program that shows that we're still inside that design basis.).

26 Exhibit INT028-00-BD01 at 2.

27 Exhibit INT051-R-00-BD01 at 1-2.

28 Id. at 1.

29 Id. (citing Exhibit INT028-00-BD01 §§ D.1, D.6, D.7.2, D.8.1 and Tr. at 981-82, 984-85, 1073-76, and 1082-83). However, when discussing expansion rate, Dr. Saouma has conceded that accelerating ASR in test specimens is acceptable because, although we get a slightly different chemical reaction and different type of gel[,] for all practical purposes, we can ignore that, Tr. at 1008, and when discussing aggregate reactivity, Dr. Saouma has conceded that, although it is interesting, in the context of ASR reaction, it is certainly not - it is not the greatest issue, Tr. at 1076.

effects significantly impact structural capacity. 30 Therefore, although the LSTP used aggregate with chemical characteristics different than those of the aggregate at Seabrook, 31 the representativeness of the LSTP test specimens with respect to structural capacity was unaffected. 32 As support for this position, the NextEra expert witnesses pointed to the fact that the industry guidance documents discussed by all parties (i.e., the FHWA Report, 33 the ISE Report, 34 and Canadian Standards Association (CSA) Report A864-00 35) correlate structural capacity with observed expansion levels and do not discuss the rate of reaction, chemical characteristics of the gel, or specific crack pattern characteristics as factors relevant to structural capacity. 36 1.8 NRC Staff expert witnesses also disputed Dr. Saoumas claim by noting that at least one industry guideline explicitly states that the amount of gel in a concrete specimen is not necessarily representative of the amount of ASR expansion. 37 An NRC Staff expert witness also testified that research at Oak Ridge National Laboratory and the National Institute of Standards 30 Exhibit NER077-00-BD01 at 4-6.

31 This was necessary to achieve bounding levels of ASR expansion in a useful timeframe. Exhibit NER077-00-BD01 at 4.

32 NER077-00-BD01 at 4-6.

33 Exhibit NER013-00-BD01.

34 Exhibit NER012-00-BD01.

35 Exhibit NRC076-00-BD01.

36 Exhibit NER077-00-BD01 at 4-6; Tr. at 988, 994-95. See also Tr. at 985 (Judge Mtingwa asking if you have two different gels, same expansion, would you often have the structural characteristics being different? and Dr. Bayrak replying [t]o our knowledge, there is no data reported in the literature that would support that line of thinking).

37 Exhibit NRC091-00-BD01 at 5 (citing Exhibit NRC076-00-BD01 at 29 (The alkali-silica gel is a characteristic feature of ASR. The presence of large amounts of gel in a concrete specimen does not necessarily indicate that large expansion or extensive cracking has occurred in the structure. On the other hand, cracking due to ASR has been observed in many concrete structures in which very little gel was found.)).

and Technology on the effect of ASR on structural capacity does not differentiate between the type of ASR gel. 38 Therefore, the NRC Staff concluded that there was no reason to believe that the exact characteristics of the gel could affect structural capacity and, in turn, impact the validity of the ASR expansion limits derived from the LSTP. 39 1.9 On balance, we find that NextEra has demonstrated by a preponderance of the evidence that the chemical characteristics of aggregate do not significantly affect structural capacity. This finding is supported by the fact that the documents in the record that address the structural impacts of ASR do not discuss the chemical characteristics of aggregate as being relevant to structural capacity. 40 Also, Dr. Saoumas claims to the contrary are, by his own admission, unsupported. 41 Therefore, a comparison of the chemical characteristics of the aggregate used in the LSTP with those of the aggregate used at Seabrook is not relevant to the question of whether the LSTP test specimens were sufficiently representative of Seabrook concrete components.

1.10 By citing in Exhibit INT051-R portions of his previous testimony that question the adequacy of the CI/CCI methodology for ASR expansion monitoring at Seabrook, 42 Dr. Saouma may also have been implying that differences in the chemical characteristics of the aggregate used in the LSTP with those of the aggregate used at Seabrook render the CI/CCI methodology 38 Tr. at 996.

39 Exhibit NRC091-00-BD01 at 5.

40 Although recognizing that expansion depends on the inherent reactivity of the aggregate, the moisture conditions, the alkali content of the mix, Exhibit NER013-00-BD01, FHWA Report at §§ C.2.1-C.2.2, these guidance documents ultimately differentiate the structural effects of ASR based on observed expansion levels, Exhibit NER013-00-BD01, FHWA Report at 37, tbl. 9; Exhibit NER012-00-BD01, ISE Report at §§ 6.3.2, 8.2.

41 Tr. at 988 (Dr. Saouma agreeing that the guidance documents dont differentiate based on differences in the chemical composition of the ASR gel, but asserting that [w]e need to open our mind as to whether the gel has a role or not).

42 Exhibit INT051-R-00-BD01 at 1.

inadequate for measuring expansion at Seabrook. However, as testified by NextEra expert witness Dr. Bayrak, the use of the CI/CCI methodology at Seabrook is not done on the basis of the LSTP; rather, it is done consistent with ASR-specific guidance documents. 43 These guidance documents do not discuss the chemical characteristics of aggregate as something relevant to the use of the CI/CCI methodology. 44 Therefore, to the extent that Dr. Saoumas argument in Exhibit INT051-R has to do with the CI/CCI methodology, it does not affect our separate finding that NextEra has demonstrated by a preponderance of the evidence that the use of CI/CCI for measuring expansion at Seabrook was appropriate. 45 II. SUPPLEMENTAL CONCLUSIONS OF LAW 2.1 After full consideration of C-10s arguments regarding the chemical characteristics of aggregate, the facts in this proceeding show that NextEra has demonstrated, by a preponderance of the evidence, reasonable assurance that, with activities authorized by the approval of the LAR, Seabrook will continue to meet GDC 1, 2, 4, 16, and 50 and Appendix B to 10 C.F.R. Part 50 without endangering the health and safety of the public.

Respectfully submitted,

/Signed (electronically) by/

Jeremy L. Wachutka Counsel for the NRC Staff U.S. Nuclear Regulatory Commission Mail Stop O14-A44 Washington, DC 20555 Telephone: (301) 287-9188 E-mail: Jeremy.Wachutka@nrc.gov Dated at Rockville, Maryland this 31st day of January 2020 43 Tr. at 482-83.

44 See, e.g., Exhibit NER013-00-BD01, FHWA Report at App. B (discussing how to perform CI/CCI and not mentioning ASR gel).

45 See NRC Staff Proposed Findings of Fact and Conclusions of Law for the Admitted Contention, at 68-70 (Nov. 21, 2019) (ML19325D909).

UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of NEXTERA ENERGY SEABROOK, LLC Docket No. 50-443-LA-2 (Seabrook Station, Unit 1)

CERTIFICATE OF SERVICE Pursuant to 10 C.F.R. § 2.305, I hereby certify that copies of the foregoing NRC STAFF SUPPLEMENTAL PROPOSED FINDINGS OF FACT AND CONCLUSIONS OF LAW, dated January 31, 2020, have been filed through the Electronic Information Exchange, the NRCs E-Filing System, in the above-captioned proceeding, this 31st day of January 2020.

/Signed (electronically) by/

Jeremy L. Wachutka Counsel for the NRC Staff U.S. Nuclear Regulatory Commission Mail Stop O14-A44 Washington, DC 20555 Telephone: (301) 287-9188 E-mail: Jeremy.Wachutka@nrc.gov