ML15126A207

Presentation Slides for Prelicensing Meeting with Arizon Public Service Company to Discuss License Amendment Request for Palo Verde, Units 1, 2, and 3,

ML15126A207
Person / Time
Site:	Palo Verde
Issue date:	05/11/2015
From:	Edington R Arizona Public Service Co
To:	Watford M Plant Licensing Branch IV
Watford M
References
TAC MF5843, TAC MF5844, TAC MF5845
Download: ML15126A207 (32)

Text

Pre-Submittal Meeting for Palo Verde Unit 1, 2, and 3 Updated Spent Fuel Pool Criticality Analysis May 11, 2015

Purpose

• Present and discuss planned licensing changes

- Update spent fuel pool (SFP) criticality analysis

- Add neutron absorbing inserts to SFP racks 2

Objectives

• Updated criticality analysis will

- Provide basis for replacing non-conservative Technical Specification (TS) caused by missed power uprate impact

- Include Next Generation Fuel (NGF) not bounded by current analysis

• Account for reactivity effects of integral fuel burnable absorber (IFBA)

- Maintain full core offload capability 3

Borated Aluminum Inserts

• Additional reactivity hold down is required to meet 10 CFR 50.68

- Thermal hydraulic, seismic, structural, and pool cooling calculations will be updated as needed

- Add a coupon surveillance program to monitor material performance 4

TS Changes

• 3.7.17 - Spent Fuel Assembly Storage

- Incorporate new burnup and enrichment curves

- Display information graphically with the polynomial explicitly stated

- Include diagrams of approved arrays 5

TS Changes (cont.)

• 4.3.1.1 - Design Features

- Incorporate new arrays

- Update boron concentration

- Reduce radially averaged enrichment from 4.8 wt% to 4.65 wt%

6

New TS 5.5.21 - Spent Fuel Storage Rack Neutron Absorber Monitoring program

- Information will include:

Periodicity for coupon testing Description of coupon testing procedure Definition of acceptance criteria, including what constitutes an adverse condition Description of process and acceptance criteria for B-10 loading analysis Description of actions to address failure to meet acceptance criteria

- Consider license extension

- Consider plant decommissioning 7

Implementation

• Prior to NGF implementation in each unit

• Considering installation inserts under 10 CFR 50.59

• Considering a license condition for a specified period of time to transition between TS 8

Methodology

• Based on

- ISG-2010-01, Staff Guidance Regarding the Nuclear Criticality Safety Analysis for Spent Fuel Pools

- NEI 12-16, Guidance for Performing Criticality Analyses of Fuel Storage at Light-Water Reactor Power Plants, Revision 1

- EPRI Depletion Benchmark Reports

- NUREGs 7109, 6698, 6760, etc.

9

Recent Licensing Actions

• Methodology similar to:

- Comanche Peak

- Prairie Island

• Insert material similar to:

- LaSalle

- Peach Bottom

- Quad Cities

• Criticality code usage similar to:

- Millstone 2 10

ISG Item 1 - Fuel Assembly Selection

• Palo Verde will demonstrate that variations in design are adequately accounted for in a single fuel assembly design

- CE Standard Fuel

- CE Value Added Pellet

- Westinghouse NGF

- AREVA Advanced CE-16 HTP

• Single, limiting, assembly will be used to create burnup requirements 11

ISG Item 2 - Depletion Analysis

• Depletion parameters will impact the isotopic inventory of burned fuel

• Major depletion inputs

- Fuel type

- Axial burnup

- Moderator temperature

- Reactor power

- Soluble boron

- Burnable absorbers 12

ISC Item 2.a - Depletion Uncertainty

• The EPRI methodology will be used to demonstrate the 5% depletion uncertainty is conservative for Palo Verde

• Fission product uncertainty explicitly considered 13

ISG Item 2.b - Reactor Parameters

• Limiting axial moderator temperature profiles derived past, present, and anticipated profiles

- Same methodology employed at Comanche Peak

• Analysis performed at 4070 MWth

• Licensee controls include verification of radial power distribution and T-cold 14

ISG Item 2.c - Burnable Absorbers Palo Verde has used the following integral burnable absorbers

- B4C rods in CE STD Fuel

- Erbia in CE STD Fuel and Value Added Pellet

- Integral Fuel Burnable Absorber (IFBA) in NGF

- Gadolinia in AREVA Fuel Analysis will not credit Erbia, B4C, or Gadolinia NGF fuel modeled with IFBA in all 236 pins for depletion analysis only

- Pool model assumes no burnable absorbers 15

ISG Item 2.d - Rodded Operation

• Palo Verde does not operate with control rods inserted

- Guide tube wear program

• End of cycle check will ensure that fuel assemblies experienced an insignificant amount of rodded operation at hot full power 16

ISG Item 3 - Criticality Analysis

• SCALE 6.1.2 will be used in the analysis

- KENO V.a solves the eigenvalue (keff) problem in 3D using the Monte Carlo method

- 238 Group ENDF/B-VII will be used as the library

- Millstone LAR used SCALE 6.0 with the KENO V.a module and 238 Group ENDF/B-VII library 17

ISG Item 3.a - Axial Burnup Profile

• Bounding axial burnup profiles selected from past, present, and anticipated profiles

- Cycle specific licensee controls include checks on cutback regions (blanket), fuel design, and moderator temperature 18

ISG Item 3.b - Rack Model

• Dimensions and tolerance of racks are traceable to design documents

• B-10 areal density conservatively modeled at quantity less than minimum certified areal density 19

ISG Item 3.c - Interfaces

• All interfaces will be evaluated

- Palo Verde has only one rack design

- No gaps modeled between rack modules

- Limiting interfaces will be analyzed 20

ISG Item 3.d - Normal Conditions

• Analysis demonstrates that keff 0.95 at less than the TS required boron concentration for:

- Fuel movement

- Fuel inspection and reconstitution

- Foreign Object Search and Retrieval

- Limiting normal condition to initiate accident identified 21

ISG Item 3.e - Accident Conditions

• Analysis demonstrates that keff 0.95 at less than the TS required boron concentration for

- Misloaded or dropped single fresh fuel assembly into, outside of, or on top of spent fuel racks

- Multiple misloaded fuel assemblies

- Loss of SFP cooling

- Seismic events 22

ISG Item 3.e (contd.)

• Limiting dilution event reduces pool boron from 2150 ppm to 1900 ppm

• TRM requires boron concentration to be maintained at 4000 ppm 23

ISG Item 4 - Code Validation

• Will perform criticality code validation in accordance with NUREG/CR-6698

- Data carefully considered to identify trends consistent with NUREG-1475

- HTC experiments will be included

• Fission products will be explicitly accounted for

- No lumped fission products will be used 24

Palo Verde Arrays 25

• Infinite array of 2 fresh fuel assemblies (Fr) with two blocked locations and no inserts Fr Fr

Palo Verde Arrays 26

• Infinite array of 2 fresh fuel assemblies (Fr) with two trash cans (TC) and two inserts Fr TC TC Fr

Palo Verde Arrays 27

• Infinite array of 3 low reactivity fuel assemblies (Lo) and 1 high (Hi) reactivity fuel assembly with 2 inserts Lo Lo Hi Lo

Palo Verde Arrays 28

• Infinite array of 2 high reactivity fuel assemblies (Hi) and one low reactivity fuel assembly (Lo) with one blocked cell and one insert Hi Lo Hi

Palo Verde Arrays 29

• Infinite array of 4 low reactivity fuel assemblies (Lo) with one insert Lo Lo Lo Lo

Palo Verde Arrays 30

• Infinite array of 4 depleted fuel assemblies (De) with no inserts De De De De

Margin Maintenance

• Palo Verde will monitor the margin identified in the analysis

• Cycle specific checks of key input parameters

• 0.005 k additional margin reserved by Palo Verde

- Burnup and enrichment curves will be for keff = 0.99 31

Conclusion

• Palo Verde is proposing an acceptable methodology for performing SFP criticality analysis

• Permanently installed borated aluminum inserts will be credited in the analysis

• Submit LAR by Nov 2015

• Request NRC approval in 18 - 24 months 32