ML17250B238

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TMRE Presubmittal NRC
ML17250B238
Person / Time
Site: Harris Duke Energy icon.png
Issue date: 08/30/2017
From:
Duke Energy Progress
To:
Office of Nuclear Reactor Regulation
Brown E
References
Download: ML17250B238 (18)
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Text

Harris TMRE LAR Presubmittal Meeting August 30, 2017 Duke/Harris Participants

  • John Caves, Licensing Engineer
  • Scott Brinkman, PRA Engineer
  • Alex Holder, Design Engineer
  • Pat Chriscoe, Harris Design Engineering Manager
  • Melvin Arey, Duke Design Engineering Manager
  • Art Zaremba, Duke Fleet Licensing Manager 2

1

Agenda

  • Purpose
  • Background

- Design and Current Licensing Basis

- Discovery Results

  • Conclusions 3

Purpose

  • License Amendment Request seeks NRC approval to amend design and licensing bases described in the FSAR to add a methodology to be utilized for determining whether unprotected systems and components require protection from tornado missiles.

TMRE would be an alternate methodology to meet regulatory requirements.

  • Requested action would restore full qualification for existing non-conforming conditions
  • Methodology would not be used for future design modifications 4

2

Purpose Proposed FSAR changes

  • Revise Section 1.8 discussion regarding RG 1.117 to say:

The SHNPP project complies with this guide except for conditions deemed acceptable using Tornado Missile Risk Evaluator (TMRE )

methodology that was approved by the NRC in [Document Name, ADAMS number]. TMRE is a methodology which can only be utilized for determining whether unprotected systems and components require protection from tornado missiles, and is not applicable to future design modifications.

5 Purpose Proposed FSAR changes (contd)

Revise Section 3.5.1.4 to include:

  • The NRC approved a license amendment in [Document Name, ADAMS number, add specific reference] for SHNPP that authorized use of the Tornado Missile Risk Evaluator (TMRE) methodology. TMRE is a methodology which can only be utilized for determining whether unprotected systems and components require protection from tornado missiles, and is not applicable to future design modifications.
  • As a result, SHNPP is in compliance with RG 1.117, Rev. 1 except for conditions of low importance to safety that were demonstrated to be acceptable using TMRE methodology

3

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Background===

Shearon Harris Nuclear Power Plant, Unit 1

  • 3-loop Westinghouse PWR
  • EBASCO prime contractor
  • Construction Permit issued January 1978
  • Operating License issued January 1987
  • Commercial operations began May 2, 1987
  • Standard Technical Specifications (Not ITS)

7 Background

Design and Licensing Basis

  • Construction Permit Issued January 27, 1978

- GDC 2: Structures, systems, and components important to safety shall be designed to withstand the effects of natural phenomena such as earthquakes, tornadoes without loss of capability to perform their safety functions

- GDC 4: Structures, systems, and components important to safety shall be designed to accommodate the effects of, and to be compatible with, the environmental conditions associated with normal operation, maintenance, testing, and postulated accidents including loss-of-coolant accidents. These structures, systems, and components shall be appropriately protected against dynamic effects, including the effects of missiles, pipe whipping, and discharging effects, that may result from equipment failures and from events and conditions outside the nuclear power unit 8

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Background===

Design and Licensing Basis (Contd)

NUREG 1038, Harris SER: Section 3.5.1

Conformance with the acceptance criteria formed the basis for the staff evaluation of the tornado-missile spectrum with respect to the applicable regulations of 10 CFR 50. The portions of the SRP review procedures concerning the probability per year of damage to safety-related systems as a result of missiles were not used in the staff review.

  • GDC 2 requires that structures, systems, and components essential to safety be designed to withstand the effects of natural phenomena, and GDC 4 requires that these same plant features be protected against missiles generated by natural phenomena. The missiles generated by natural phenomena of concern are those resulting from tornadoes. The applicant has identified a spectrum of missiles for a tornado Region I site as identified in RG 1.76, Position C.l, and has utilized missile Spectrum A of SRP 3.5.1.4 as the basis for the design of tornado-missile protection.
  • The applicant has identified all safety-related structures, systems, and components requiring protection from externally generated missiles. All safety-related structures are designed to withstand postulated tornado-generated missiles without damage to the safety-related equipment they contain.

9 Background

Design and Licensing Basis (Contd)

NUREG 1038, Harris SER, Section 3.5.2

  • The applicant has identified all safety-related structures, systems, and components requiring protection from externally generated missiles. All safety-related structures are designed to withstand postulated tornado-generated missiles without damage to the safety-related equipment they contain. All safety-related systems and components and stored fuel are located within tornado-missile-protected structures or are provided with tornado-missile barriers. Buried safety-related systems such as piping and electrical circuits are protected by the overlaying earth.

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Background===

Design and Licensing Basis (Contd)

NUREG 1038, Harris SER, Section 3.5.2 (contd)

Based on the above, the staff concludes that the applicant's list of safety-related structures, systems, and components to be protected from externally generated missiles and the provisions in the plant design providing this protection are in accordance with the requirements of GDC 2 and 4 with respect to missile and environmental effects and the guidelines of RG 1.13, Position C.2; RG 1.27, Positions C.2 and C.3; and RG 1.117, Positions C.1 through C.3, concerning protection of safety-related plant features, including stored fuel and the ultimate heat sink, from tornado missiles.

11 Background

Design and Licensing Basis (Contd)

  • UFSAR Section 1.8, Conformance to NRC Regulatory Guides

- RG 1.76, Design Basis Tornado for Nuclear Power Plants

  • Harris complies with RG 1.76, Rev. 0.
  • The Harris Nuclear Plant adopts the guidance provided in Regulatory Guide 1.76 Revision 1 as an optional design basis for new system modifications occurring after March 2007.

- RG 1.117, Tornado Design Classification, Rev. 1

  • The SHNPP project complies with this guide.

12 6

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Background===

Design and Licensing Basis (Contd)

UFSAR Section 2.3, Meteorology

  • The SHNPP site lies within Region I for determining the Design Basis Tornado (Reference 2.3.1-2). The Region I associated Design Basis Tornado parameters are as follows:

Maximum wind speed 360 mph Rotational wind speed 290 mph Translational speed 70 mph maximum; 5 mph minimum Radius of maximum rotational speed 150 ft.

Pressure drop 3.0 psi Rate of pressure drop 2.0 psi/sec.

  • Calculation of the tornado strike probability: Consequently, one would expect a tornado strike every 944 years.

13 Background

Design and Licensing Basis (Contd)

UFSAR Section 3.1 Compliance with NRC GDC 3.1.2 Criterion 2 - Design Bases for Protection Against Natural Phenomena

  • The structures, systems and components important to safety are protected from or designed to withstand the effects of natural phenomena without loss of capability to perform their safety functions.
  • The most severe natural phenomena considered in the design in terms of induced stresses are the safe shutdown earthquake (SSE) and the design basis tornado. Structures, systems and components essential to the safe shutdown of the plant are designed to withstand the effects of the most severe natural phenomena, including floods, hurricanes, tornadoes or the SSE, as appropriate.

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Background===

Design and Licensing Basis (Contd)

UFSAR Section 3.1 Compliance with NRC GDC

  • 3.1.4 Criterion 4 - Environmental and Dynamic Effects Design Bases

- Structures, systems, and components are designed, arranged or protected such that the external missiles will not cause an accident which could result in the release of significant amounts of radioactivity or prevent safe plant shutdown.

- Failure of high pressure lines external to the Containment will not cause a LOCA, or prevent safe shutdown of the Unit.

15 Background

Design and Licensing Basis (Contd)

UFSAR Section 3.3 Wind and Tornado Loadings Structures, systems, or components whose failure, due to design wind loading, tornado wind loading, or associated missiles, could prevent safe shutdown of the reactor, or result in significant uncontrolled release of radioactivity from the unit, are protected from such failure by one of the following methods:

a) the structure or component is designed to withstand design wind, tornado wind and tornado generated missiles, or b) the system or components are housed within a structure which is designed to withstand the design wind, tornado wind and tornado generated missiles.

Table 3.3.0-1 lists all safety related structures and the method of wind/tornado protection as applicable. The Ta or Tb designation in the table refers to item a or b above.

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Background===

Design and Licensing Basis (Contd)

UFSAR Section 3.5 Missile Protection 3.5.0 The following criteria were adopted for assessing the plant's capability to withstand the missiles postulated in Sections 3.5.1.1 and 3.5.1.2:

a) No perforation of the Containment Building (i.e., no loss of leak tightness) b) Assurance that the plant can be maintained in a safe shutdown condition c) Offsite exposure within 10 CFR 100 guidelines for missile damage resulting in radioactivity release.

17 Background

Design and Licensing Basis (Contd)

UFSAR Section 3.5 Missile Protection 3.5.0 Missile Selection and Description Barriers are provided for missiles which cannot be oriented to take advantage of existing structures and which could cause failure of safety-related structures or components. Generally, these barriers are designed to contain or deflect the missiles from the safety related feature; but, as a minimum requirement, penetration of the missile through the barrier reduces the missile energy to levels which cannot cause failure of the safety feature function. Wherever possible, advantage is taken of walls and structures arising from functional requirements, other than missile considerations, by judicious arrangement of equipment.

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Background===

Design and Licensing Basis (Contd)

UFSAR Section 3.5 Missile Protection 3.5.0 Missile Selection and Description Sources considered capable of generating potential missiles are as follows:

a) Tornadoes All Seismic Category I structures are designed to withstand the tornado generated missiles specified in the "Missile Spectrum" of the Standard Review Plan 3.5.1.4 (Rev. 0) and listed in Table 3.5.1-3. All Seismic Category I structures are designed with f'c=4000 psi concrete and a minimum thickness of 24 inches in roofs and walls.

19 Background

Design and Licensing Basis (Contd)

UFSAR Table 3.5.1-3, Tornado-generated Missile Spectrum Missile Weight Area (ft2) Velocity (fps)

1) Wood Plank 200 .333 422 4 in. x 12 in. x 12 ft.
2) Steel Pipe 3 in. x 10 ft. 78 .0155 211 schedule 40
3) Steel Rod 1 in. x 3 ft. 8 .00545 317
4) Steel Pipe 6 in. x 15 ft. 285 .0388 211 schedule 40
5) Steel Pipe 12 in. x 15 ft. 743 .1014 211 schedule 40
6) Utility Pole 131/2 in. x 35 ft. 1490 .994 211
7) Automobile 4000 20 106 These missiles are considered to be capable of striking in all directions. Missiles 1, 2, 3, 4 and 5 are considered at all elevations and Missiles 6 and 7 for elevations up to 30 feet above the highest grade level within 1/2 mile of the facility structures.

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Background===

Design and Licensing Basis (Contd)

UFSAR Section 3.5.1.4 Missiles Generated by Natural Phenomena

  • All structures that house systems and components to be protected against tornado generated missiles and the types of protection have been presented in Table 3.5.1-2.
  • The characteristics of the tornado generated missiles considered in the plant design are given in Table 3.5.1-3. The missiles listed in this table are considered as striking in all directions.

21 Background

Design and Licensing Basis (Contd)

UFSAR Section 3.5.1.4 (Contd)

Structures, systems, and components whose failure could prevent safe shutdown of the reactor or result in significant uncontrolled release of radioactivity from the Unit are protected from such failure due to design tornado and wind loading of missiles by the following methods:

a) Structure or component is designed to withstand tornado loading or tornado missile.

b) Component is housed within a structure which is designed to withstand the tornado loading and tornado missile.

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Background===

Design and Licensing Basis (Contd)

UFSAR Section 3.5.2 SSCs to be Protected from Externally Generated Missiles Structures, systems, and components whose failure could prevent safe shutdown of the reactor or result in significant uncontrolled release of radioactivity from the Unit are protected against externally generated missiles; they are listed in Table 3.5.1-2 Most safety-related systems are located within structures that are specifically designed and constructed to withstand external missiles; therefore they are adequately protected. The penetrations, access openings, and HVAC air intake and exhaust openings in these safety-related structures are protected by steel doors and/or concrete barriers designed to withstand external missiles.

23 Background

  • Harris identified non-conforming conditions during 2016 discovery walkdowns

- Entered into Corrective Action Program

- Assessed for Operability

- Enforcement Guidance Memorandum (EGM) 15-002 and DSS-ISG-2016-01 invoked as appropriate

- Conditions meeting reporting criteria reported in EN 52072 and Licensee Event Report 2016-001 (ADAMS Accession No. ML16245A804).

  • Examples of non-conforming conditions in safety-related systems

- Emergency Diesel Generator - missile could penetrate steel door to impact fuel line

- Emergency Service Water - outside air temperature sensors that control pump room ventilation not protected

- Essential Services Chilled Water - chill water expansion tanks not protected

- Main Steam Safety Valves - Vent stacks exposed 24 12

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Background===

  • RIS documented opportunity to disposition non-compliant conditions using NRC approved risk-informed methodology

- NEI 17-02, TMRE Industry Guidance Document, was provided to NRC staff for information on June 23, 2017 and discussed at July 6, 2017, public meeting

- Appendices A through E provide technical bases for the methodology

- NEI 17-02 will be revised and provided to the NRC

- Revised methodology will be incorporated by reference into License Amendment Request 25 TMRE Evaluation

  • Standard PRA practices used for non-TMRE-specific analyses
  • Evaluation did not deviate from TMRE guidance
  • Missile count assumption in TMRE confirmed conservative

- Site missile count of 139,000 < 240,000 in TMRE

  • Some issues dispositioned as negligible impact consistent with standard PRA practices with justification For example, PRA room heat up analysis shows the battery room ventilation is not needed for success in the PRA model. This non-conformance is evaluated as having a negligible impact on risk from tornado missiles.
  • Site-specific tornado hazard curve developed IAW TMRE 26 13

TMRE Evaluation Harris Tornado Hazard Curve 300 HNP F5 F4 y = -22.8ln(x) - 98.333 250 R² = 0.9985 200 F3 150 HNP F2 Log. (HNP) 100 50 0

1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 27 TMRE Evaluation

  • Operator Actions reviewed to assess feasibility following tornado

- Most retained because they were performed in Main Control Room or Reactor Auxiliary Building

- Some disallowed, such as manual control of PORV which would require travel through exposed path 28 14

TMRE Evaluation Example Exposed Equipment Failure Probabilities Turbine Driven Aux Feed Pump exhaust pipe Area: 16 ft2 Elevation: < 30 Robust type J (Not Robust)

Robust Missile F-Scale MIP EEFP Event Name EEFP Missiles % Count 100% 155000 2 1.10E-10 FHWTDPEXF2 2.73E-04 100% 155000 3 3.60E-10 FHWTDPEXF3 8.93E-04 100% 205000 4 6.30E-10 FHWTDPEXF4 2.07E-03 100% 240000 5 1.60E-09 FHWTDPEXF5 6.14E-03 100% 240000 6 2.40E-09 FHWTDPEXF6 9.22E-03 29 TMRE Evaluation Example Exposed Equipment Failure Probabilities EDG Fuel Oil Line Area: 2 ft2 Elevation: < 30 Robust type G (Partial protection from steel door)

Robust Missile F-Scale MIP EEFP Event Name EEFP Missiles % Count 45% 69750 2 1.10E-10 PHWDGFO_F2 1.53E-05 45% 69750 3 3.60E-10 PHWDGFO_F3 5.02E-05 45% 92250 4 6.30E-10 PHWDGFO_F4 1.16E-04 45% 108000 5 1.60E-09 PHWDGFO_F5 3.46E-04 45% 108000 6 2.40E-09 PHWDGFO_F6 5.18E-04 30 15

TMRE Evaluation PRA Modeling

  • Selected operator actions failed - Examples Event Name Description OPER-27 FAILURE TO LOCALLY OPERATE ANY SG PORV OPER-43 FAILURE TO RE-ENERGIZE BUS 1A1 (NVDCS CHARGER) AND RECOVER OFFSITE AC OPER-45 FAILURE TO LOCALLY ALIGN OFFSITE AC BREAKERS OPER-74 OPERATOR FAILS TO OPEN PUMPHOUSE INNER DOORS
  • Selected equipment failed from high winds equipment List - Examples Event Name Description TPDE0001FN DSDG FAILS TO RUN TPDE0001NN DSDG FAILS TO START ACP1ANNSSR IA COMPRESSOR 1A-NNS FAILS TO RUN 31 TMRE Evaluation Quantification Results Result CDF LERF Type per Year per Year Degraded 5.44E-7 5.77E-8 Compliant 5.22E-7 5.55E-8 Delta 2.2E-8 2.2E-9 Initiating Event Contribution

% CDF  % CDF Event Name Frequency Contribution Contribution Description Degraded Compliant

%TMRE_F2 1.10E-04 73.8% 75.3% TMRE Tornado Event F2

%TMRE_F3 2.75E-05 19.4% 18.9% TMRE Tornado Event F3

%TMRE_F4 7.05E-06 5.4% 4.8% TMRE Tornado Event F4

%TMRE_F5 1.33E-06 1.3% 0.9% TMRE Tornado Event F5

%TMRE_F6 7.09E-08 0.04% 0.02% TMRE Tornado Event F6 32 16

TMRE Evaluation Target Contributions - Examples CDF CDF Target Group Contribution Contribution Degraded Compliant Emergency Diesel Generator Train A 1.37E-08 0 Emergency Diesel Generator Train B 8.08E-09 0 RWST 8.63E-09 7.90E-09 Emergency Service Water Train A 0 0 Emergency Service Water Train B 2.23E-10 0 MSIV Bypass A 1.27E-10 0 MSIV Bypass B 0 0 MSIV Bypass C 6.96E-11 0 33 Conclusions

  • Range of delta CDF impact ranged from below the truncation limit to 1.4E-8/year
  • Aggregate impact of non-conformances was 2.2E-8/year
  • No deviations from TMRE methodology were identified
  • LAR will address five key principles of risk-informed decision making (RG 1.174)

- Meets current regulations

- Consistent with and maintains defense-in-depth

- Maintains safety margins

- Increase in risk is small and consistent with NRC Safety Goal Policy

- Impact will be monitored

  • PRA quality - No open findings on internal events model 34 17

End of Presentation 35 18

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