UNITED STATES

NUCLEAR REGULATORY COMMISSION 

REGION I 

2100 RENAISSANCE BLVD., SUITE 100 

KING OF PRUSSIA, PA 19406-2713 

December 23, 2015 

LICENSEE: NextEra Energy Seabrook, LLC 

FACILITY: Seabrook Station, Unit 1 

SUBJECT: SUMMARY OF TELEPHONE CONFERENCE CALL HELD ON 

DECEMBER 22, 2015, BETWEEN THE NRC AND NEXTERA 

CONCERNING A REQUEST FOR ADDITIONAL INFORMATION 

PERTAINING TO SEABROOK STATION OPERABILITY 

DETERMINATIONS FOR THE ALKALI-SILICA REACTION (ASR)-

AFFECTED CONTAINMENT ENCLOSURE BUILDING AND THE 

RESIDUAL HEAT REMOVAL EQUIPMENT VAULT 

The NRC Region I and Division of License Renewal staffs and representatives of NextEra 

Seabrook Station held a telephone conference call on December 22, 2015 to discuss and clarify 

the NRC’s request for additional information concerning the ongoing operability evaluations for 

ASR-affected structures at Seabrook Station. The telephone conference call was useful in 

clarifying the purpose and scope of the ongoing Problem Identification and Resolution (PI&R) 

inspection of this issue and the additional information requested by the staff to complete the 

inspection. 

Enclosure 1 provides the list of participants and Enclosure 2 contains the list of questions and 

information requested of NextEra to support the staff’s inspection effort. 

Docket No. 50-443 

License No. NPF-86 

Enclosures: 

1. List of Participants 

2. Question and Information Request 

ADAMS ML15357A326 
ENCLOSURE 1

Telephone Conference Call 

Seabrook Station, Unit 1 

List of Participants

December 22, 2015 

Participants Affiliation

Mel Gray NRC 

William Cook NRC 

Paul Cataldo NRC 

Chris Newport NRC 

Angela Buford NRC 

Bryce Lehman NRC 

Michael Collins NextEra 

Brian Brown NextEra 

Al Dodds NextEra 

Rick Noble NextEra 

Ted Vasallo NextEra 

Ken Browne NextEra 

Mike Ossing NextEra 
ENCLOSURE 2

Seabrook Station – 4th Quarter PI&R Sample Inspection - December 22, 2015 

Containment Enclosure Building (CEB) Local Deformation – Root Cause Evaluation 

(CR 2014325) Review - Questions 

1) What is the role of the Finite Element Analysis (FEA) with respect to a CEB structural 

analysis (FP 100985) and its applicability to an update/revision to the open Prompt 

Operability Determination (POD) for the CEB (AR 01664399)? 

2) If used in support of an update/revision to the POD, provide a comprehensive description of 

the FEA, with applicable inputs, assumptions and outputs, to the NRC staff for review. 

3) The following are specific FEA review issues/questions of interest to the NRC staff include: 

a) What variable or input to the FEA was used to mimic ASR expansion (reference 

p. 12); 

b) What variable or input to the FEA was used to mimic backfill ASR expansion 

and what load values were used/assumed and the basis for those values 

(reference p. 15); 

c) An ASR-attributed expansion value of between 0.03 and 0.14% was used to 

represent the circumferential growth and associated deformation in the FEA. 

What is the rationale for applying this block/wall design expansion value to a 

cylindrical design model? And, what conservatisms or uncertainties are 

introduced as a result? (p. 14); 

d) How was the FEA model developed and validated? How was it derived and/or 

compared to the original UE&C design/construction model and the 2012 CEB 

FEA model used to inform POD AR 01664399? 

4) What is the basis for the conclusion that CEB bulk expansion, and associated deformation 

has plateaued (p.38)? Absent conclusive evidence, what monitoring is planned or in place 

to validate this conclusion and provide assurance that further deformation does not 

compromise CEB structural performance? 

5) What is the significance of the FEA model output identifying that the deformation values at 

+22 foot – azimuth 210 and +119 foot (Springline) are not consistent with actual field 

measurements (p.15)? What additional actions and/or field measurements does NextEra 

have planned in order to address this apparent disparity? 

6) How will the results of the FEA be used to update the CEB POD, beyond the assessment of 

the seismic gaps? Specifically, has the CEB deformation and the assumed backfill ASR 

expansion (and associated loading) added any additional loads on the ASR-affected 

structures that potentially undermine the current POD margins analyses? 
2 

7) Based upon NextEra’s proposed methodology for bulk expansion and deformation 

monitoring, what acceptance criteria, thresholds, or triggers will be established to prompt 

follow-up corrective actions or further structural evaluations? 

8) The current PODs for ASR-affected structures highlight that ASR is a localized 

phenomenon. How does the FEA modeling assumption of uniformly applied ASR expansion 

across various elevations and assumed expansion rates impact the validity of the FEA and 

the validity of the current margins-based PODs for all ASR-affected structures? 

9) What physical evidence supports your conclusion that the CEB deformation is attributable to 

ASR? This question relates to question 8) above. To date, we understand that only four 

cores have been removed from the CEB and there are a limited number of CCI locations 

being used for ASR monitoring. Absence a broader sampling of cores and petrographic 

exams, what confidence does NextEra staff have that the bulk expansion and associated 

deformations observed are appropriately associated with ASR, albeit a localized 

phenomenon? 

10) Does NextEra plan to update the docketed Integrated ASR Corrective Action Plan with the 

results of the CEB RCE? 

11) Is there (or are there plans to develop) an assessment of impact of global deformation in 

terms of rebar stress, including pre-stress, to understand the impact of this structural 

attribute on the current licensing basis (CLB) limits? 

RHR Vault Operability Update - Questions 

1) FP100903, Condition Assessment of Cracking in the RHR and CS Equipment Vault, 

identifies ASR as the probable cause for the structural cracking and observed deformations. 

FP 100903, Section 5.2, refers to UE&C design calculation set No. PB-30 with respect to a 

limited structural analysis. Does NextEra plan to update/revise the current RHR Vault POD 

based upon the insights provided by FP100903? 

2) If revising the RHR Vault POD, provide the supporting structural analysis for NRC staff 

review. Include the specific modeling assumptions and associated calculations for the 

interior through-wall crack (discontinuity) at the minus 26-foot elevation. 

3) Please provide an update on the progress of NextEra’s corrective actions and associated 

monitoring efforts for the RHR Vault.