IR 05000282/2018011

NRC Design Bases Assurance Inspection (Teams); Inspection Report 05000282/2018011 and 05000306/2018011 (DRS-A.Dunlop)

ML18214A386
Person / Time
Site:	Prairie Island
Issue date:	08/01/2018
From:	Jeffers M NRC/RGN-III/DRS/EB2
To:	Sharp S Northern States Power Company, Minnesota
References
IR 2018011
Download: ML18214A386 (19)

Text

ust 1, 2018

SUBJECT:

PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2NRC DESIGN BASES ASSURANCE INSPECTION (TEAMS); INSPECTION REPORT 05000282/2018011 AND 05000306/2018011

Dear Mr. Sharp:

On May 25, 2018, 2018, the U.S. Nuclear Regulatory Commission (NRC) completed a Triennial Baseline Design Bases Assurance Inspection (Teams) at your Prairie Island Nuclear Generating Plant, Units 1 and 2. On June 21, 2018, the NRC inspectors discussed the results of this inspection with yourself and other members of your staff. The results of this inspection are documented in the enclosed report.

Based on the results of this inspection, the NRC has identified one issue that was evaluated under the risk significance determination process as having very low safety significance (Green). The NRC has also determined that a violation is associated with this issue. Because the licensee initiated a condition report to address this issue, this violation is being treated as Non-Cited Violation (NCV), consistent with Section 2.3.2 of the Enforcement Policy. This NCV is described in the subject inspection report.

If you contest the violation or significance of the NCV, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region III; the Director, Office of Enforcement; and the NRC Resident Inspector at the Prairie Island Nuclear Generating Plant.

If you disagree with a cross-cutting aspect assignment or a finding not associated with a regulatory requirement in this report, you should provide a response within 30 days of the date of this inspection report, with the basis for your disagreement, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region III; and the NRC resident inspector at the Prairie Island Nuclear Generating Plant. This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with 10 CFR 2.390, Public Inspections, Exemptions, Requests for Withholding.

Sincerely,

/RA/

Mark T. Jeffers, Chief Engineering Branch 2 Division of Reactor Safety Docket Nos. 50-282; 50-306 License Nos. DPR-42; DPR-60 Enclosure:

IR 05000282/2018011; 05000306/2018011 cc: Distribution via ListServ

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring licensees performance by conducting a Design Bases Assurance Team Inspection at Prairie Island Nuclear Generating Plant, Units 1 and 2, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.

NRC and self-revealed findings, violations, and additional items are summarized in the table below.

List of Findings and Violations Failure to Justify Load Combinations Used in Main Steam Piping Stress Analysis Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green [H.6] - CCA Design 71111.21M NCV 05000282/2018011-01; Margins05000306/2018011-01 Opened and Closed Inspectors identified a Green finding and associated Non-Cited Violation of Title 10 of the Code of Federal Regulations, Part 50, Appendix B, Criterion III, Design Control, for the licensees failure to correctly translate provisions from specified quality standards for load combinations into piping analysis. Specifically, in the analysis for the Class I main steam piping, the licensee combined the seismic Operating Basis Earthquake and safety relief valve operating loads by Square Root of Sum of Squares. Prairie Island Updated Safety Analysis Report and the Engineering Manual for piping system stress analysis do not permit the Square Root of Sum of Squares method for combining these loads.

Additional Tracking Items Type Issue Number Title Report Section Status URI 05000282/2018011-02; Potential Failure to Protect IP 71111.21M Open 05000306/2018011-02 Class I Structures, Systems, and Components from Tornado Generated Missiles URI 05000282/2012005-06; Concerns with the Analytical IP 71111.21M Closed 05000306/2012005-06 Methods Used for Predicting Void Transport Behavior

INSPECTION SCOPES

===Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter 2515, Light-Water Reactor Inspection Program -

Operations Phase. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.

REACTOR SAFETY

===71111.21MDesign Bases Assurance Inspection (Teams)

The inspectors selected the components listed below based on high risk. The inspectors evaluated the following components and listed applicable attributes, permanent modifications, and operating experience:

Component ===

(1) Unit 1 Diesel Generator (D1) including Jacket Water and Lube Oil Components a) Material condition and configuration (i.e., visual inspection during a walkdown)b) Operating procedures c) Maintenance effectiveness d) Component health, corrective maintenance, and corrective action history e) Consistency between station documentation (e.g., procedures) and vendor specifications f) Generator loading g) Diesel starting circuit components voltage h) Diesel generator breaker close circuit voltage i) Diesel generator rating limitations j) Preventive maintenance for Lube Oil Strainer, Filter, Pump, and Heat Exchanger k) Preventive maintenance for Jacket Water Pump and Heat Exchanger l) Jacket Water Coolant Pressure Test m) Chemistry of the Jacket Water and Lube Oil

(2) D1 Diesel Generator Room Ventilation Supply Fan (032-041) and Exhaust Fan (032-011)a) Material condition and configuration (i.e., visual inspection during a walkdown)b) Fan and damper voltage c) Fan motor protection d) Room heat up calculations e) Preventive maintenance for Supply Fan and Exhaust Fan

(3) 125 VDC Battery 11 a) Panel voltage calculations b) Component voltage calculations c) DC loading list d) Hydrogen generation and removal calculation e) Battery charger sizing calculation f) Battery sizing calculation g) Material condition and configuration (i.e., visual inspection during walkdown)h) Battery room cooling system procedure i) Station Battery and DC Distribution System procedure j) Failure of 11 Battery Fuse procedure k) Failure of 11 Battery Charger procedure l) Operating procedures m) Alarm procedures

(4) Pressurizer Outlet Motor-Operated Valve to Pressurizer Relief Tank A (MV-32195)a) Valve motor voltage b) Valve motor thrust calculation c) Calculations for adjacent section of piping and pipe supports d) Performance of preventive maintenance and inservice testing e) Seismic qualification documentation f) Closure/Opening time calculation Component Large Early Release Frequency (1 Sample)===

(1) Unit 1 Main Steam Isolation Valve (CV-31099)

a) Material condition and configuration (i.e., visual inspection during a walkdown)b) Calculations for adjacent section of piping and pipe supports c) Corrective actions associated with stress analysis deficiencies d) Performance of surveillance and inservice testing e) Calculations for disc impact, structural, and seismic analyses f) Seismic qualification documentation g) Electrical calculations for actuating solenoid during degraded conditons h) Control logic design i) Instrument air supply Permanent Modification (7 Samples)

(1) Engineering Change (EC) 23724, DC Panel 12 Fused Switch Replacement;

===(2) EC 23818, Slow Down Closure of DDCLP Jacket Heat Exchanger Control Valve;

(3) EC 24160, Replace D1/D2 Actuators, Controllers, Transmitters, and Sensing Elements;

(4) EC 14537, Replace U1 & U2 Cooling Water Pump Power Cables from Motors to JB Splice;

(5) EC 27319, SV-33188 & SV-33189 Replacement HT8211D3 TO EE8210P095 100-240V/50-60HZ/DC, Supports;

(6) EC 09478, Unit 2 Pressurizer Power Operated Relief Valve Accumulator Upgrade for Low Temperature Overpressurizer Postulated Event; and

(7) Calculations PI-50046-S01, Design of Missile Barrier for D1 EDG at Door 72 and the Padeyes, and PI-50046-S02, Design of Padeye for 4,000 lb Redundant (2,00 lb non-redundant) Lifts.

Operating Experience (1 Sample)===

(1) 10CFR21 Report, Basler Automatic Voltage Regulator Circuit Card Solder Connection Defect, MPR.

Review of Previously Identified Inspection Issues

(1) Non-Cited Violation 05000282/2015007-02; 05000306/2015007-02; Inadequate Calculations for Motor-Operated Valve Thermal Overload Relays.

INSPECTION RESULTS

71111.21MDesign Bases Assurance Inspection (Teams)

Failure to Justify Load Combinations Used in Main Steam Piping Stress Analysis Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green [H.6] - CCA Design 71111.21M NCV 05000282/2018011-01; Margins05000306/2018011-01 Opened and Closed Inspectors identified a Green finding and associated Non-Cited Violation of Title 10 of the Code of Federal Regulations, Part 50, Appendix B, Criterion III, Design Control, for the licensees failure to correctly translate provisions from specified quality standards for load combinations into piping analysis. Specifically, in the analysis for the Class I main steam piping, the licensee combined the seismic Operating Basis Earthquake (OBE) and safety relief valve operating loads by Square Root of Sum of Squares (SRSS). Prairie Island Updated Safety Analysis Report (USAR) and the Engineering Manual (EM) for piping system stress analysis do not permit the SRSS method for combining these loads.

Description:

Calculation PI-221-08 (including Revision 0 issued in 1973, with an addendum Revision 0A issued in 1994), herein referred to as old calculation, was the design basis analysis of record for the Class I main steam piping analysis until being superseded by calculation 09Q4836-CAL-001, Unit 1 Main Steam Pipe Stress Analysis, in 2014. The old calculation addressed the load combination of the OBE and the safety relief valve thrust loads, and it used absolute sum method for combining these loads.

An error was identified in the old calculation as documented in Action Request (AR) 01223633, dated March 22, 2010, indicating that the seismic accelerations used in the calculation did not include the rotational components as required by the plant seismic design basis. This AR determined the main steam piping to be Operable But Non-Conforming and identified corrective actions to restore the system to full qualification. Corrective actions for this error are currently ongoing. Part of these actions included Revision 1 to Calculation 09Q4836-CAL-001, which was issued on May 10, 2014. Inspectors noted a change from the previous analysis involving the method for combining the OBE with valve thrust loads. These loads were now combined by SRSS method rather than absolute sum. Page 122 of the calculation identified the valve loads as occasional loads (OCC) and referred to Design Information Transmittal No. 16083-006 for the SRSS justification, which in turn referred to a position paper for the justification. Inspectors reviewed position paper PI-996-140-R01, Acceptability of Square Root of the Sum of Squares Combination of Dynamic Responses, dated February 25, 2014, but did not find a justification for the use of SRSS in the calculation. Inspectors noted the position paper, in addition to indicating acceptability of the SRSS method for combining the seismic with water hammer based on NUREG 1061, Report of the U.S. Nuclear Regulatory Commission Piping Review Committee, (Section 1.3, Volume 4, September 1984), reiterated the conclusions in NUREG 0484, Methodology for Combining Dynamic Responses, Revision 1, generally allowing SRSS for combining Loss of Coolant Accident (LOCA) with Safe Shutdown Earthquake (SSE) only. The NUREG 0484 also concluded that other dynamic loads could be combined using SRSS provided a non-exceedance probability of 84 percentage or higher is achieved for the combined SRSS response, and that an acceptable method for achieving that goal is outlined in Section 4, Condition A and Condition B. Section 4 of the NUREG described the criteria for use of the SRSS as conditions A and B and stated that should a case not meet the response combination criteria, the responses shall be combined by absolute sum. The licensee did not provide any evaluation demonstrating that the required conditions for use of SRSS were met.

Inspectors also reviewed the applicable USAR sections and specification governing the piping and component design. The USAR Tables 12.2-13 (for B31.1 piping) and 12.2-15 (for Class I components) describe the stress limits under various load conditions such as Normal, Upset, Faulted, etc. which are defined in Section 12.2.1.5.2.1, Class I Vessels, Piping, and Supports.

The Upset Condition includes transients/system upset not resulting in forced outage, and the effect of the specified earthquake for which the system must remain operational. Based on this description, the inspectors determined the Upset Condition included the OBE and valve thrust loads. Footnotes under USAR Table 12-2-11, Load Combinations for Components, specify that the DBE (Design Basis Earthquake, same as SSE) and LOCA may be combined by SRSS per Reference 66, which is the NUREG 0484 discussed above. There is no statement permitting use of SRSS for OBE and valve thrust loads. Section 3.2.1.1 of the EM is the specification applicable to piping stress analyses. Inspectors reviewed Revision 7 of the specification (as referenced in calculation 09Q4836-CAL-01) and found that Section 6.3.10 described the Upset load condition which included a combination of OBE and valve loads.

While Prairie Island is a pre-Standard Review Plan plant, inspectors noted that this definition of the Upset condition is consistent with NUREG 800, Section 3.9.3, Revision 1, 1981.

Section 6.3.10 of the EM does not specify use of SRSS for load combination including OBE and valve thrust loads.

Based on this review, the inspectors concluded the use of SRSS for combining the OBE and valve thrust loads was not consistent with the USAR, the stress analysis engineering manual, the previous analysis of record, or the NRC guidance documents (NUREG reports referenced in the USAR and the EM); and that the licensee had not documented adequate justification for such application. Inspectors determined since the deficiency only involved the calculation to demonstrate full qualification of the system, the operability of the system was not affected in that AR 01223633 concluded the system was already Operable but Non-Conforming.

Corrective Action: The licensees CAP recommended evaluation of the use of SRSS to combine valve thrust and seismic loads in calculation 09Q4836-CAL-001 R1 Corrective Action Reference: AR 501000013515

Performance Assessment:

Performance Deficiency: Inspectors determined the failure to apply the correct method for combining seismic loads with valve thrust loads in the piping analysis, as described in the USAR and the EM was a performance deficiency. Specifically, combining OBE and safety relief valve thrust loads in Calculation 094836-CAL-001, Revision 1, using SRSS for an Upset loading condition was not permited per USAR Table 12.2-11 and EM 3.2.1.1, and superseded previous analyses of record that used the absolute sum method.

Screening: The inspectors determined the performance deficiency was more-than-minor because it adversely affected the Mitigating Systems cornerstone attribute of design control and affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, failure to apply correct load combinations involving a design basis earthquake could result in pipe overstress leading to degradation/failure of the main steam piping.

Significance: The inspectors assessed the significance of the finding using SDP Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The finding screened to Green (very-low safety significance) because it did not involve a loss of function under a design basis seismic event. Specifically, operability of the main steam piping or supports was not affected by the calculation performance deficiency.

Cross-cutting Aspect: While the subject calculation was performed in 2014, more than 3 years ago, inspectors determined this to be indicative of present performance because it reflected the current understanding of the licensee staff associated with on-going corrective actions including field modifications resulting from the previously identified seismic issue and can potentially impact the scope of such actions. The finding had a cross-cutting aspect in the Design Margins component of the Human Performance cross-cutting area, which states that the licensee operates and maintains equipment within design margins. Specifically, the licensee did not perform a rigorous evaluation for changing to a less conservative method of combining dynamic loads for safety related main steam piping. (H.6)

Enforcement:

Violation: Title 10 of the Code of Federal Regulations, Part 50, Appendix B, Criterion III, Design Control, states, in part, Measures shall be established to assure that applicable regulatory requirements and the design basis, as defined in § 50.2 and as specified in the license application, for those structures, systems, and components to which this appendix applies are correctly translated into specifications, drawings, procedures, and instructions.

These measures shall include provisions to assure that appropriate quality standards are specified and included in design documents and that deviations from such standards are controlled.

The USAR Table 12.2-11 states for Normal and Design Basis Earthquake and Pipe Ruptures for components designed to ASME Section III, Code Class 1, 2, or 3 requirements, the DBE and the LOCA loads may be combined using the SSRS methodology per Reference 66 (NUREG 0484, Revision 1) provided a linear elastic stress analysis is performed.

The NUREG 0484, Methodology for Combining Dynamic Responses, Revision 1, issued in May 1980, in Section 5 states that SRSS is appropriate for combination of SSE and LOCA dynamic responses. However, for combining responses of dynamic loads other than LOCA and SSE, it states that the use of the SRSS is appropriate provided a non-exceedance probability of 84% or higher is achieved for the combined SRSS response, and that an acceptable method for achieving that goal is outlined in Section 4, Condition A and Condition B. Section 4 of the report describes the criteria for use of the SRSS as conditions A and B and states that should a case not meet the response combination criteria, the responses shall be combined by absolute sum.

Engineering Manual (EM) 3.2.1.1, Specification for the Stress Analysis of Piping System, Revision 7, (a quality standard) Section 6.3.10 defines the load combination for UPSET condition (Design Class I) as Pressure + Dead weight + (OCC + OBE). The OCC is defined as the stress or resultant load due to any occasional loading [dynamic loads] such as safety relief valve operation, flow transient, thermal stratification, etc.

A note under Section 6.3.10, states that for components designed to ASME Section III, Code Class 1, 2 or 3 requirements, the seismic (OBE or SSE) and HELB [High Energy Line Break]

loads may be combined using the square root sum of the squares methodology provided a linear elastic stress analysis is performed. It refers to USAR Table 12.2-11 and the NUREG 0484, Revision 1 for additional information.

Contrary to the above, on May 10, 2014, the licensee failed to assure that the appropriate quality standards, in particular, the USAR, EM 3.2.1.1, and NUREG 0484 were specified and included in design document Calculation 09Q4836-CAL-001, Revision 1, or control deviations from these standards. Specifically, the licensee extended the use of the SRSS method to load combinations used for Class I OCC and OBE loading of the main steam piping design for determining UPSET condition, for which the SSRS method is not specified as an allowable method in the USAR, EM or NUREG. In addition, the licensee did not perform an evaluation demonstrating that the use of the SRSS method for these load combinations of other than seismic and HELB/LOCA loads is an acceptable method.

Disposition: This violation is being treated as a Non-Cited Violation, consistent with Section 2.3.2 of the Enforcement Policy.

Unresolved Item Potential Failure to Protect Class I Structures, IP 71111.21M (Open) Systems, and Components from Tornado Generated Missiles05000282/2018011-02; 05000306/2018011-02

Description:

Inspectors identified a number of structure, systems, and components (SSCs)that lacked protection from tornado generated missiles. The following SSCs were identified:

Division 1 and Division 2 Emergency Diesel Generators (D1/D2 EDGs) engine exhaust, fuel oil day tank vents, and main fuel oil storage tanks vents; and Diesel Driven Cooling Water Pumps (DDCWPs) main fuel storage tank vents, day tank vents, engine exhausts, and rooms ventilation intake and exhaust equipment. In various cases susceptible SSCs for redundant equipment (e.g. fuel tank vents) were right next to or within a few feet of each other such that a single missle could affect both trains of the system.

A review of the sites licensing bases, including the original FSAR, identified the D1/D2 EDGs and the DDCWPs as Class I, safety-related SSCs, which are required to be designed to withstand, without loss of capability, environmental phenomena including tornadoes and tornado generated missiles. Specifically, the current USAR Table 12.2-1, Classification Of Structures, Systems and Components, list both systems as Class I and has two notes of interest. Note 1 applies to the Diesel Generators and their associated [Main] Fuel Oil Storage Tank, which states, in part, The indicated Design Class I is applicable to D1/D2 Diesel Generators and associated [emphasis added] safety related components and systems. The second note is listed at the beginning of the Table, which states, in part, To determine detail design classifications and boundaries separating different design classes within the overall classification scheme listed here, refer to controlled drawings. A review of controlled drawings, including NF-39255-1, Flow Diagram Diesel Generators D1 & D2 Unit 1 & 2, Revision 85, and NF-39232, Flow Diagram Fuel & Diesel System Unit 1 & 2, Revision 86, showed the fuel oil vents for the main storage tanks, fuel oil vents for the day tanks, engine exhaust piping, mufflers, and silencers for the D1/D2 EDGs and DDCWPs were classified as safety-related Class I SSCs.

A review of the current UFSAR identified the following sections of interest:

The USAR Section 1.5.I, Overall Plant Requirements, Criterion 2 - Performance Standards, Answer, established in part The system and components designated Class I in Section 12, in conjunction with administrative controls and analysis, as applicable, are designed to withstand, without loss of capability to protect the public, the most severe environmental phenomena ever experienced at the site with appropriate margins included in the design for uncertainties in historical data The USAR Section 12.2.1.1.a, Classification of Structures and Components, defines Design Class I as Those structures and components including instruments and controls whose failure might cause or increase the severity of a loss-of-coolant accident or result in an uncontrolled release of substantial amounts of radioactivity, and those structures and components vital to safe shutdown and isolation of the reactor.

The USAR Section 12.2.5.1.g.1, Protection for Class I Items, establishes, in part, that Class I items are protected against damage from: Missiles from different sources. These sources comprise: Tornado created missiles.

The USAR Section 12.2.1.3.2.c., Tornado Loads, defines the design tornado driven missile as assumed equivalent to an airborne 4 x 12 x 120 plank travelling end-on at 300 mph, or a 4000 lbs automobile flying through the air at 50 mph and at not more than 25 feet above ground level.

Based on the above, the inspectors were concerned the susceptible SSCs could lose the capability to perform their safety-related function if they were impacted by tornado generated missiles. For example, an impact to the fuel oil vents could crimp the vent path resulting in a vacuum inside the tanks that could collapse the tank and/or cause the associated fuel transfer pump to lose net positive suction head.

The licensee provided a position paper proposing the susceptible SSCs identified by the inspectors were meeting their current licensing bases and no further actions were required.

The inspectors disagreed, but decided to request support from the Office of Nuclear Reactor Regulation (NRR) to obtain clarification on the sites licensing bases related to tornado generated missiles.

Planned Closure Action: The inspectors have requested NRR to provide clarification on the sites current licensing bases regarding tornado generated missiles required protection.

Licensee Action: Licensee is considering doing a self-review of design and licensing basis of the fuel oil storage tank vent lines to understand and clarify design class of the lines.

Corrective Action Reference: 501000012997

OTHER ACTIVITIES

TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL 71111.21MDesign Bases Assurance Inspection (Teams)

INSPECTION SCOPE

The inspectors reviewed the status of Unresolved Item (URI)05000282/2012005-06; 05000306/2012005-06, Concerns with the Analytical Methods Used for Predicting Void Transport Behavior. The URI had been opened pending further evaluation and determination of acceptability by NRR staff. Specifically, NRR staff were asked to consider the licensees analytical measures as they relate to:

(1) applying the test results contained in the WCAP-17271-P, Air Water Transport in Large Diameter Piping Systems: Analysis and Evaluation of Large Diameter Testing Performed at Purdue University, (ML110490356), report to void assessment analysis;

(2) the use of computer software for void transport analysis of the sump voids; and

(3) using the simplified method contained in the WCAP-17276-P, Investigation of Simplified Equation for Gas Transport (ML110480381), report for locations 1RH-03 and 2CS-06.

This did not constitute an inspection sample.

INSPECTION RESULTS

Unresolved Item Concerns with the Analytical Methods Used for Predicting IP 71111.21M (Closed) Void Transport Behavior 05000282/2012005-06; 05000306/2012005-06

Description:

As required by the available guidance at the time the URI was opened, regional inspectors requested support from NRR, Division of Safety Systems, Reactor Systems Branch for their input and assessment. Inspectors provided NRR the originally available information when the URI was opened and information documenting the licensee current computer software used to evaluate voids (S-RELAP5). The inspector discussed with the licensee and its contractor (AREVA) to better understand the current state of the various voids in question and the methodology used to evaluate these using the new computer software.

Corrective Action Reference: N/A Closure Basis: By letter dated March 19, 2013 (ML13136A129), the NRC staff provided a Final Safety Evaluation of Nuclear Energy Institute Topical Report NEI 09-10, Revision 1a, "Guidelines for Effective Prevention and Management of System Gas Accumulation," and determined NEI 09-10, Revision1a, was acceptable for use, with limitations. The NEI 09-10 document is an industry developed guidance intended to provide insights and attributes to implement an acceptable approach to effectively prevent and manage gas intrusion and accumulation in plant systems.

Regarding URI aspect (1), application of test results contained in WCAP-17271-P, NRR determined in its safety evaluation (SE) that WCAP-17271-P provided a valuable addition to data applicable to two-phase two-component transient pipe flow. Use of the data in verifying void transport methodologies is acceptable subject to the conditions identified in the SE.

Regarding URI aspect (2), use of computer software for void transport analysis of the sump voids, inspectors noted the licensee had changed the original software used when the URI was opened. The licensee changed the software used from PIPER Q2.05, SYSFLO Q3.08, and AIRDST codes in their original evaluations to S-RELAP5. NRRs review determined the licensees approach used the most up-to-date information available at the time coupled with what appeared to be a reasonably conservative approach to the computer analyses. Some of the conservative measures included using larger void volumes than expected, piping pressures that would result in void expansion with pump start, and acceptance criteria based on NRCs conservative percentages at that time. With regards to the use of S-RELAP5, NRR staff concluded this software was similar to the original evaluation in its approach of conservation of energy, mass, and momentum. This was confirmed through discussion with the licensee and its contractor AREVA. As a result, NRR staff had reasonable assurance that the licensee used appropriate evaluation methods from what was available at the time. Regarding the currently existing voids between the containment sump isolation valves (1RH-22, 1RH-23, 2RH-24, and 2RH-25), the inspectors verified the actual or maximum previously identified voids volumes were bounded by the licensees evaluation performed using the S-RELAP5 software.

Regarding URI aspect (3), using the simplified equation method contained in WCAP-17276-P for previously identified voids in locations 1RH-03 and 2CS-06, the inspectors were concerned from a past operability perspective. These voids had already been vented at the time the URI was opened. The inspectors noted NRR had generically addressed the applicability of the WCAP-17276-P in the above mentioned SE. Specifically, the simplified equation method was found acceptable subject to the conditions identified in the SE. In addition, the licensee evaluated these voids using the S-RELAP5 software and associated evaluations. The inspectors verified the maximum previously identified voids volumes for locations 1RH-03 and 2CS-06 were bounded by the evaluation. As a result, the inspectors no longer had past operability concerns regarding the previously identified voids.

Based on the above and NRRs review, no violations of NRC requirements were identified.

This URI is considered closed.

EXIT MEETINGS AND DEBRIEFS

The inspectors confirmed that proprietary information was controlled to protect from public disclosure. The inspectors verified no proprietary information was retained or documented in this report.

On June 21, 2018, the inspectors presented the Design Bases Assurance Team inspection results to Mr. Scott Sharp, and other members of the licensee staff.

DOCUMENTS REVIEWED

71111.21MDesign Bases Assurance Inspection (Teams)

Calculations

- 0951S-10-79; Stress Analysis - PRSR SYS Safety and Relief LN (Unit 1); Revision 1C

- 09Q4836-CAL-001; Unit 1 Main Steam Line Pipe Stress Analysis; Revision 1

- 09Q4836-CAL-001-MSH-48; Unit 1 Main Steam Pipe Support 1-MSH-48; Revision 0

- 09Q4836-CAL-002; Updated Disc Impact Analysis of Main Steam Check and Isolation Valves;

Revision 0A

- 09Q4836-CAL-003; Updated Structural Analysis of Main Steam Check and Isolation Valves;

Revision 0A

- 250800-C-014; Seismic Capacity of Concrete Block Walls; Revision 01A

- 91-02-11; Battery 11 Calculation; Revision 3

- ENG-EE-001; 11 Battery Charger Sizing Calculation; Revision 02

- ENG-EE-021; Diesel Generator Steady State Loading for an SI Event with Loss-of-Offsite-

Power (LOOP) for D1, D2, D5, D6; Revision 7

- ENG-EE-024; C&D Hydrogen Calculation; Revision 1

- ENG-EE-045; Diesel Generator Steady State Loading for a LOOP Coincident with and SBO;

Revision 7

- ENG-EE-184; Large Motor Loads for D1 and D2 Transient Analysis; Revision 0

- ENG-EE-197; Master DC Load List; Revision 01

- ENG-EE-200; PINGP ETAP 125 VDC Electrical Analysis; Revision 0C

- ENG-ME-026; EDG Ventilation Analysis; 02/18/1993

- ENG-ME-046; MOV Target Thrust/Torque Calculation (MV-32195); Revisions 7C, 8

- ENG-ME-334;Section XI Design Basis Valve Stroke Times; Revision 6C

- ENG-ME-613; EPRI PPM, Flowserve Size 3 Special Class 1530DD Gate Valves; Revision 0

- ENG-ME-617; Design Report with Seismic Weak Link Analysis Flowserve Size 3 Class 1530

S. S. Double Disc Gate Valve; Revision 0

- PI-50046-S01; Design of Missile Barrier for D1 EDG at Door 72; Revision 3

- PI-50046-S02; Design of Padeye for 4000 lb Redundant (2000 lb non-redundant) Lifts;

Revision 1

Corrective Action Documents Generated Due to the Inspection

- PCR 602000004909; 1C37.10 Rev. 22 Update; 05/10/2018

- Issue ID 501000011817; 2018 DBAI - Error in 1C37.10 Purpose Section; 05/10/2018

- Issue ID 501000012312; 2018 DBAI - Records Could not be Located; 05/22/2018

- Issue ID 501000012156; 2018 DBAI - Questions Needed Revision; 05/18/2018

- Issue ID 501000011866; 2018 DBAI - D1 Vent Louvers; 05/10/2018

- Issue ID 501000012180; 2018 DBAI - Errors in ENG-ME-630; 05/18/2018

- Issue ID 501000011830; 2018 DBAI - Block Wall Calc Considerations; 05/09/2018

- Issue ID 501000012539; 2018 DBAI - Piping Analysis Documentation; 05/29/2018

- Issue ID 501000012569; 2018 DBAI - Rigging Process Concern; 05/29/2018

- Issue ID 501000012123; 2018 DBAI - D1/D2 Vent Duct Interference; 05/17/2018

- Issue ID 501000012265; 2018 DBAI - Battery Float Current; 05/22/2018

- Issue ID 501000011729; 2018 DBAI - SP 1083A Table 20; 05/08/2018

- Issue ID 501000011862; 2018 DBAI - PID Drawing SC Coding Error; 05/10/2018

- Issue ID 501000012482; 2018 DBAI - D1/D2 Air Cooler Derate; 05/25/2018

- Issue ID 501000012301; 2018 DBAI - D1/D2 Load Rating Concern; 05/22/2018

- Issue ID 501000013515; 2018 DBAI - Evaluate the use of SRSS; 06/21/2018

- Issue ID 501000012997; 2018 DBAI - Classification of EDG FOST Vent Line; 06/06/2018

Corrective Action Documents Reviewed During the Inspection

- AR 01541096; PINGP 1066 Form Could not be Found; 11/08/2016

- AR 01516986; D1/D2 Derate due to High Combustion Air Temps; 03/28/2016

- AR 01215223; Upset Loads on Snubbers 1-MSH-48 and 2-MSH-23; 01/25/2010

- AR 01227543; MS Snubbers Overloaded - Torsional Acceleration; 04/16/2010

- AR 01397436; Main Steam Piping Tracking GAR; 09/19/2013

- AR 01113023; Part 21 - Defective Analog Electronic Circuit Card; 09/25/2007

- AR 01223633; MS Stress Analysis Omitted Seismic Torsional Acceleration; 03/22/2010

- AR 01468790; 2015 CDBI FSA Long Standing Equip Issue Identified; 03/05/2015

- AR 01491302; CDBI 2015: RHR Sump Recirc Valves Duty Cycle; 8/27/15

- AR 01522379; POD Compensatory Measure Removed on 12/07/15 in Error; 5/18/16

Drawings

- M1480; AC Motor Performance Curves; 7/21/77

- NE-40006; D1 Emergency Generator Bus 15 Cubicle 2 (EG System) Sheet 49; Revision PV

- NE-40008; D1 Emergency Generator Room 121 Exhaust Fan Sheet 79; Revision 76

- NE-40008; D1 Emergency Generator Room 121 Supply Fan Sheet 76; Revision 76

- NE-40008-39; 11 Containment Sump B Control Diagram; Revision BU

- NE-40009; D1 Emergency Generator (X-HIAW 28-8, 26, 27, & 46) Sheet 74; Revision 76

- NE-40009; D1 Emergency Generator (X-HIAW 28-8, 26, 27, 46 & 47) Sheet 72; Revision 78

- NE-40009; D1 Emergency Generator (X-HIAW 28-8A, 26, 27, & 46) Sheet 73; Revision 78

- NE-40322-1; Interlock Logic Diagram Main Steam System Unit 1; Revision 77

- NF 38500; Architectural Ground Floor Plan at Elev 695-0; Revision 79

- NF-38299-3; Auxiliary Building - Concrete EL. 715-0 Mezzanine Floor Outline; Revision 77

- NF-39218; Flow Diagram Main Auxiliary Steam & Steam Dump, Unit 1; Revision 84

- NF-39232; Flow Diagram Fuel & Diesel System Unit 1 & 2; Revision 86

- NF-39255-1; Flow Diagram Diesel Generators D1 & D2 Unit 1 & 2; Revision 85

- NF-39601; HVAC Flow Diagram Turbine Building - Diesel Generator Unit 1 & 2; Revision 89

- NF-40022-1; Circuit Diagram 4KV & 480V Safeguards Buses Unit 1; Revision 78

- NF-40022-2; Single Line Metering and Relaying 4.16KV Switchgear Bus 15 and 16 D1 and D2

Emergency Generator; Revision 77

- NF-40100; Grounding Details and Notes; Revision 0

- NF-40101-1; Grounding Layout - Ground Floor; Revision 76

- NF-40301-1; Wiring Diagram DC Distribution Panels A Train; Revision 83

- NX-19644-14; Schematic 21 Inverter 5KVA Inverter System 129V DC- 120V AC, 1 Phase 60

Hz; Revision 77

- SK-C-EC23405-S-001; Missile Barrier Protection # 1, Sheets 1/2; Revisions 4/3

- SK-C-EC23405-S-001; Missile Barrier Protection # 3, Sheets 1/2; Revisions 4/2

- SK-C-EC23405-S-002; Missile Barrier Protection # 2, Sheets 1/2; Revisions 4/3

- XH-106-241; Main Steam From Steam Generator 1B ISO Drawing; Revision 77

- XH-106-335-1; Unit 1 Pressurizer Power Operated Relief Piping; Revision 77

- XH-112-1; Main Steam Isolation Valve and Check Valve; Revision 78

- XH-1-7; Flow Diagram, Reactor Coolant System Unit 1; Revision 92

- XH-48-43; Piping Schematic Raw Water Piping to Heat Exchanger; Revision 77

CFR 50.59 Documents (Screenings/Safety Evaluations)

- 1239; Resize/Replacement of Motor Overload Relays Using H 6.1 and H 6.2; Revision 1

- 3424; EC 14537 Replace U1 & U2 CLG WTR PMP Power Cables From MTRS to JB Splice;

Revision 1

- 4868; DC Panel 11, 12, 21, 22 Fused Switch Replacement; Revision 0

- 5062; POD 1491302 Compensatory Measures; Revision 0

- 5154; EC 24160 Replace D1/D2 Actuators, Controllers, Transmitters, and Sensing Elements;

Revision 0

- 5249, SV-33189 & SV-33189 Replacement HT8211D3 to EE8210P095 100-240V/50-

60HZ/DC; Revision 0

Miscellaneous

- CV-31099; Seismic Qualification Screening Evaluation Work Sheet, 12 LOOP B MN STM

HDR ISOL CV; Revision 0

- D1 EDG Sump Oil Report; 07/10/2017 to 03/11/2018

- IB 6.2.1.7C; ABB Installation/Maintenance Instructions Medium - Voltage Power Circuit

Breakers Type 5HK 1200 thru 3000 Amperes 5000 Volts

- MDB0220; Xcel General Report Final; 05/09/2018

- MDC0154; Xcel General Report Final; 05/09/2018

- MDD0146; Xcel General Report Final; 05/09/2018

- Pioneer Service & Engineering Co. Diesel Generator Rooms D1 & D2 Ventilation;

06/14/1973

- Publication No. 9064300-103; Operation and Service Manual Series Boost Exciter - Regulator

Part No. 9064300-103; 08/1970

- Limitorque Test Report B0037; Seismic Qualification Envelope - Limitorque Valve Actuators

(Appendix F)

- SPEC E20001; Stand By Generator; 08/03/1983

Modifications

- EC 09478; Unit 2 PRZR PORV LTOP Upgrade; Revision 000

- EC 14537; Replace U1 & U2 CLG WTR PMP Power Cables From MTRS to JB Splice;

Revision 000

- EC 19663; Evaluation Of D1/D2 Room Temperatures for Summer Conditions; Revision 001

- EC 22881; Slow Down Closure of DDCLP Jacket HX CV; Revision 000

- EC 23724; DC Panel 12 Fused Switch Replacement; Revision 000

- EC 26563; Incorporate Lessons Learned from Panel 22 Installation on Panel 12; Revision 000

- EC 23818; Slow Down Closure of DDCLP Jacket HX CV; Revision 000

- EC 24160; Replace D1/D2 Actuators, Controllers, Transmitters, and Sensing Elements;

Revision 000

- EC 24248; Evaluation of D1/D2 Room Temperatures for Summer Conditions With a Room

Temp Limit of 123.7F (125F-1.3F); Revision 000

- EC 24800; Evaluation of D1/D2 Room Temperatures for Summer Conditions with a Room

Temp Limit of 123.7F and the Ventilation Fans in the Low Flow Position; Revision 000

- EC 25414; Evaluation of D1/D2 Room Heat Up With a Room Temperature Limit of 123.7F and

Degraded Max Flow on the Ventilation Fans; Revision 000

- EC 27319; SV-33188 & SV-33189 Replacement HT8211D3 TO EE8210P095 100-240V/50-

60HZ/DC, Supports; Revision 000

- EC 27502; As-Built ECN for EC 23724; Revision 000

Operability Evaluations

- OPR 01327157-01; D1/D2 Non-Conservative Heat Up Analysis; Revision 07

- POD 01327157-01; D1/D2 Non-Conservative Heat Up Analysis; Revision 08

- POD 01491302; Recirculation Sump Pump Valves Two Stroke Cycle Capability; Revision 2

Procedures

- 1C1.2-BOP; Unit 1 Balance of Plant System Startup; Revision 5

- 1C1.3 AOP 2; Cooldown from Outside of the Control Room Unit 1; Revision 11

- 1C1.3-BOP; Unit 1 Balance of Plant Systems Shutdown; Revision 2

- 1C18.1; Engineered Safeguards Equipment Support Systems; Revision 48

- 1C20.5 AOP 6; Reenergizing 4.16kV Bus 15 or 16 Using Local Manual Actions; Revision 0

- 1C20.7 AOP 1; Failure of D1 or D2 Lube Oil Keep Water System; Revision 8

- 1C20.7 AOP 2; Bus 15 Load Sequencer Out of Service; Revision 13

- 1C20.7; D1/D2 Diesel Generators; Revision 49

- 1C20.9 AOP1; Loss of Unit 1 Train A DC; Revision 7

- 1C20.9 AOP3; Failure of 11 Battery Charger; Revision 16

- 1C20.9 AOP5; Failure of 11 Battery Fuse; Revision 7

- 1C28.1; Auxiliary Feedwater System Unit 1; Revision 29

- 1C37.10; D1/D2 Diesel Generator Room Cooling system; Revision 22

- 1E-0; Reactor Trip or Safety Injection; Revision 35

- 1ECA-0.0; Loss of All Safeguards AC Power; Revision 28

- 1ECA-0.1; Loss of All Safeguards AC Power Recovery Without SI Required; Revision 16

- 1ES-0.1; Reactor Trip Recovery; Revision 30

- AB-2; Tornado/Severe Thunderstorm/High Winds; Revision 42

- AB-3; Earthquakes; Revision 37

- B38A; Unit 1 Diesel Generators; Revision 12

- C20.2 AOP 1; Restoration of Offsite Power Sources Following Station Blackout; Revision 1

- C20.9; Station Battery and DC Distribution System; Revision 33

- C31 AOP 1; Fire Protection Line Break; Revision 3

- C37.15; Battery Room Cooling System; Revision 20

- C47024; Alarm Response Procedure; Revision 44

- C47041; Annunication Location 47041 AR 20; Revision 15

- C55300; D1 Diesel Generator Remote Alarm Responses; Revision 11

- D70.1; Motor Operated Valve Testing; Revision 22

- EM 3.3.1.3; Diesel Generator Loading Assessment Methodology; Revision 7

- EM 3.3.2.10; 125VDC Safety Related Design Basis Scenario; Revision 3

- F5 Appendix F; Fire Hazard Analysis; Revision 34

- H 6.1; Motor Operated Valve Thermal Overload Heater Sizing for GE MCCS, Revision 5, 7

- H10.1.B; ASME Inservice Testing Program; Revision 39

- MSIP 1004; Valve Packing; Revision 21

- PE 3001-4-D1; D1 Diesel Generator Inspection; Revision 6

- PE 4875; Testing of Cables Rated Greater than 600 Volts; Revision 2

- SWI O-35; Emergency Operating Procedure Verification, Validation & Maintenance; Revision

Work Documents

- WO 00303680; PM 3148 - 11 D1 Diesel Generator Supply & Exhaust Fan PM; 01/10/2007

- WO 00403441; Replace 11 CLG WTR P Cable 13408-2 per EC 14537; 01/06/2011

- WO 00404249; Replace 11 CLG WTR P Cable 23404-2 per EC 14537; 03/03/2011

- WO 00415768; PM - 121 D1 DG SPLY (032-041) & EXHT (032-011) Fans; 12/14/2010

- WO 00437920; PM 3001-2-D1 - D1 Diesel Gen (034-011) Inspection; 12/19/2012

- WO 00468888; PE-0008 - Overhaul BKR 15-2 (D1 DSL GEN) DSL BKR; 03/11/2016

- WO 00469626; PE 3001-6-D1 DSL GEN Control Relay Replacements; 05/04/2015

- WO 00469907; Screen Needs Cleaning; 12/19/2012

- WO 00470032; PM - 121 D1 DG SPLY (032-041) & EXHT (032-011) Fans; 09/04/2015

- WO 00472881; PM 3001-2-D1 - D1 Diesel Gen (034-011) Inspection; 11/10/2014

- WO 00475483-01; Replace D1 Relays Bench Tested & Replaced; 10/05/2016

- WO 00475483-03; Replace D1 Relays Bench Tested & Replaced; 05/04/2015

- WO 00479270; OPS: SP1406 MSIV Inservice Test; 06/04/2017

- WO 00489173; IC: 2CL-151-1, Install Flow Control Valve per EC 22881; 03/22/2014

- WO 00503679; Mech: Replace FCV 2CL-151-1 with Metering Valve; 04/01/2015

- WO 00515421; Install Flow Control Valve Upstream of SV-33776 per EC 23818; 03/26/2015

- WO 00516473; PM 3001-2-D1 - D1 Diesel Gen (034-011) Inspection; 10/14/2016

- WO 00517562; Intergrated SI Test; 11/11/2916

- WO 00517977; Obtain Flow Data to Support D1 Temperature Modeling; 05/24/2015

- WO 00559172; Adjust D1 Room Exhaust Fan Positioners; 05/31/2017

- WO 70014315; D1 DG 6 Month Fast Start; 03/11/2018

- WO 70022701; D1 DG Monthly Slow Start; 04/09/2018

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