ML082671209

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TMI Pre-Application Meeting - Control Rod Drive Control System Upgrade and Elimination of Axial Power Shaping Rods
ML082671209
Person / Time
Site: Three Mile Island Constellation icon.png
Issue date: 09/23/2008
From:
AmerGen Energy Co
To:
Office of Nuclear Reactor Regulation
Bamford, Peter J., NRR/DORL 415-2833
References
Download: ML082671209 (17)
v • d • e


Text

AmerGenlNRC TMI-1 Pre Submittal Meeting 9/23/08 Control Rod Drive Control System Upgrade and Elimination of Axial Power Shaping Rods

AmerGen Team

  • Dave Helker Licensing Manager
  • Frank Mascitelli Licensing Engineer
  • Charlie Hartman DCRDCS Project Manager
  • Dennis Hull DCRDCS Lead Engineer
  • Jen Hays CRD System Manager
  • Bob Jaffa APSR Lead Engineer 2

Acronyms

  • APSR Axial Power Shaping Rod
  • DNB Departure from Nucleate Boiling
  • LAR License Amendment Request
  • LOCA Loss of Coolant Accident
  • PIDC Power Imbalance Detector Correlation
  • TS Technical Specifications 3

Key Messages

  • Requesting approval for TS Changes associated with:

- Adding Zone Reference Switch Position Indication

- Removing Relative Position Calibrations

- Removing Patch Panel

  • Requesting approval for the new RTB Configuration Change

- The RTB Configuration Change is not Digital

-, Similar to approved Oconee system

  • Requesting approval to remove APSRs permanently from reactor core
  • DCRDCS upgrade will be performed under 50.59 4

DCRDCS - What

  • TMI will install the AREVA-designed DCRDCS to replace existing CRDCS
  • The Triple Modular Redundant base system is the same as that installed at Oconee Nuclear Station

- Replaces Group Power Supplies with Single Rod Power Supplies

- Replaces relay based logic with digital logic

- Replaces analog modules with digital processing

- Provides In-Limit Lights that are independent of DCRDCS

  • The DCRDCS does not perform any Safety Related Function 5

L *. II

DCRDCS-Why

  • Resolve obsolescence and age related degradation Issues
  • Benefits

- Resolves single point vulnerability

- Simplified Operator Interface (no transfers)

- Improved monitoring and diagnostics

- Improved Position Indication

- Improved circuit protection

- Simplified maintenance 6

RTB - What

  • Replaces 6 RTB s and electronic trips with 4 Reactor Trip Breakers
  • Utilizes SquareD MasterPact breakers qualified by Nuclear Logistics Inc
  • RTBs do not utilize digital components

RTB - Why

  • Control System change requires new RTB configuration
  • Simplified RTB configuration requires fewer components
  • New RTBs require less maintenance to maintain high reliability 8

DCRDCS - Differences from Oconee

  • TMI Control System does not include Group 8 (Axial Power Shaping Rods)
  • TMI will install a Flat Panel Display for Control Rod Position Indication
  • TMI will display zone reference switch status and LAR will request use to verify rod position
  • DSS Actuation will be modified to match Oconee

- DSS presently trips upstream breakers at TMI

- DSS will trip electronic trips in DCRDCS

- DSS is independent of the Reactor Protection System 9

L

DCRDCS / RTB - TS Impact

  • Delete calibration requirement for Relative Position Indication
  • Delete requirement to lock patch panels

- Replace with commitment for patch verification

  • Add use of Zone Switches for Position Indication
  • Change to reflect new RTB configuration

- Removes non-safety SCRs from Reactor Protection System function

  • Revise the corresponding TS Bases (for information only) 10

APSRs - What

  • APSRs were originally designed for axial power control in less stable rodded cores
  • TMI transitioned from rodded cores to stable non rodded feed and bleed operation in Cycle 4 (1978)
  • Since 1994 APSRs have not been used for axial power control
  • Axial power imbalance can be controlled with Group 7 Regulating Rods and with planned borations or dilutions 11

APSRs - Why

  • Prevent possibility of future end of cycle fuel rod defects due to pellet clad interaction during APSR withdrawal maneuvers
  • Eliminate unnecessary control components
  • Eliminate the need for scheduled APSR replacement
  • Eliminate the need to provide for Group 8 controllers in the DCRDCS Upgrade 12

APSRs - Technical Evaluation

  • Suppression of Axial Oscillations
  • Power Imbalance Detector Correlation Test
  • Safety Analysis
  • Core Operating Limits 13

APSRs - Technical Evaluation

  • Safety Analysis

- No credit for APSRs in any events

- Increased Bypass Flow

  • Core hydraulic lift analysis

APSRs - TS Impact

  • Delete APSRs from Control Rod Group and Power Distribution Limits
  • . Delete APSRs for controlling Axial Power Imbalance
  • Remove APSRs as a Reactor Design Feature
  • Revise the corresponding TS Bases (for information only) 15 l- . ~

Attachment 1 TMI-1 Evaluation of Proposed Changes for the Control Rod Drive Control System and Elimination of Group 8 Axial Power Shaping Rod Assemblies 480VAC 480VAC Power Power Supply A SupplyB AC AC Switchgear Switchgear Breaker Breaker 1G*2A 1L*2A

]--------1 i--------[

I I I I I I I I I Voltage Regulator I I Voltage Regulator

~lJ:IST I

I Transformer

~io-RPSA RPSB~ I I Transformer 470 VAG 3 Phase/ I I I 470 VAC 3 Phase/

= 96 VAG 6 Phase _ :O-RPSC RPS D -Q....!...Q .. 96 VAC 6 Phase E

F C*DC D-OC Breakers Breakers CB1 CB3 CB2 CB4 Safety Groups GP1, GP2, GP3, GP4 Regulating Groups GP5, GP6, GP7, GP8 Figure 1 Existing Control Rod Drive Control System and Reactor Trip Breaker Configuration Page 12 of 20

Attachment 1 TMI-1 Evaluation of Proposed Changes for the Control Rod Drive Control System and Elimination of Group 8 Axial Power Shaping Rod Assemblies Digital Control Rod Drive Control System and Reactor Trip Breaker 480VAC Configuration 480VAC Power Supply Power Supply A B 1G-2A Reactor 1l-2A Manual Trip )

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ReactorTrip Breaker

~ -1'~V~ I RPS A RPS B ~l~v ~- , ReactorTrip Breaker A ST B 1 ST I

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I I  :  : I ReactorTrip Breaker -~

~v i. ~ RPS C l l ~i RPS D ~ .

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Reactor Trip Breaker C  ! ST __ .J L.-- ST  ! D

,---_ _......L._ _- - , i i Voltage Regulator i i Voltage Regulator I SRPS A SRPS B I Transformer

\ UV/OV UV/OV i Transformer 470 VAC 3 Phase/

\ i 470 VAC 3 Phase/

96 VAC 6 Phase

\ i 96 VAC 6 Phase

\ i

\ i

,/

Single Rod Power Control I TMR Controller Control Single Rod Power Supply Power Module A I Drive Gate (PLC) Gate Drive Supply Power Module B (Typical of 61) Inhibit Inhibit (Typical of 61)

/ Trip / Trip RC Press A

~rr DSS RC Press B 6 Windings - Switched DC CRDM Motors (Typical of 61)

Figure 2 New Digital Control Rod Drive Control System and Reactor Trip Breaker Configuration Page 13 of 20

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