ML053620270

Enclosure 4 to Summary of Public Meeting with the Boiling Water Reactor Owner'S Group to Discuss 10 CFR Part 21 Report on Safety Limit 2.1.1.1 of NUREG 1433/34

ML053620270
Person / Time
Site:	Hatch
Issue date:	12/12/2005
From:	Vidal O BWR Owners Group, Southern Nuclear Operating Co
To:	Office of Nuclear Reactor Regulation
Roth D
References
NUREG-1433, NUREG-1434
Download: ML053620270 (17)

Text

BW04 Proposed Solutions to Part 21 on Safety Limit w 2.1.1.1, NUREG-1433/34 R

0rl Ozzie Vidal, Principal Engineer m

G Southern Nuclear Operating Company 0

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(n Plant Hatch C:

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• December 12, 2005 1

Agenda

> Introduction and Purpose

> Presentation i Overview of SL 2.1.1.1 Part 21 i Description

• Evaluation i Subcommittee X Proposed Solutions

• Descriptions

• Advantages and Disadvantages X Schedule X Discussion IBWRI OWNERS'GROUP 2

Introduction and Purpose Meeting is intended to provide NRC with the current status of the SL 2.1.1.1 Part 21 issue, and to solicit some feedback. This involves discussion of:

• Two proposed Technical Specifications solutions Resolution schedule 3

Overview of Part 21/Description v GE Issued on March 29, 2005, as a reportable condition per 21.21(d)

• SL 2.1.1.1 requires that with reactor steam dome pressure below 785 psig or core flow below 10%0/of rated, THERMAL POWER shall be < [25%] of rated (Value can be lower for extended power uprate plants)

• SL 2.1.1.1 intended to preclude the need for CPR calculations below 785 psig e SL provides conservative bounding conditions for fuel cladding integrity protection during start-up 4

Overview of Part 21/Description

• Problem discovered with at-power pressure regulator failure-open (PRFO) transient upon evaluation with newer models

• Early models predict a reactor level swell resulting in turbine trip and subsequent reactor scram

• Newer models predict that level may not increase to the turbine trip

• New models then predict the depressurization is terminated by MSIV closure scram at low pressure isolation setpoint OWNERS'GROUP 5

Overview of Part 21/Description

• Steam dome pressure could decrease to below 785 briefly with thermal power still above 25%

of rated, "violating" the SL A scram on MSIV closure position would occur, and, therefore, the time above 25% is very brief OWNERS' GROUP kj6

Overview of Part 21/Evaluation

• Depressurization transients increase the critical bundle power and decrease the bundle power

• This results in an increase in the critical power ratio, CPR=CP/AP

• Application of SL 2.1.1.1 is, therefore, overly conservative for this depressurization transient since the event does not threaten fuel cladding integrity 7

Subcommittee

• Subcommittee of Technical Specifications Issues Coordination Committee (TSICC) was formed in May, 2005

• Purpose to develop a proposed generic Technical Specifications (TS) change to the BWR NUREGs and to consider longer term solutions

• Members from SNC, Detroit Edison, GE, TVA, Entergy, Exelon, NMC, and Progress Energy 8

Subcommittee

• Subcommittee has met four times

• Two proposed TS/Bases changes are currently under consideration

• TS Bases only change

• TS change which eliminates SL 2.1.1.1 and creates a new LCO in Power Distribution limits section 3.2

• A longer term solution is being discussed with GE which involves lowering the steam dome pressure value in the SL.

Other fuel vendors (Framatome/Westinghouse) already have lower acceptable value OWNERS' GROUP 9

Proposed Solutions/Description

• Proposed Solution #1, Bases only change--

• SL 2.1.1.1 stays as-is

• A paragraph is inserted into Applicable Safety Analysis section of B 2.1.1 indicating that SL 2.1.1.1 is not applicable during depressurization transients

• Similar wording added to Applicability section of B 2.1.1

- Eliminate tie to SL 2.1.1.1 in section B 3.3.6.1, Main Steam Line (MSL) Pressure-Low (Per part 21, MSL low pressure should not be an LSSS for protecting SL 2.1.1.1) 10 OWNERS'GROUP

Proposed Solutions/Description

• Proposed Solution #2^ TS and Bases change

• Eliminates SL 2.1.1.1 and corresponding Bases

• Creates new Limiting Condition of Operation (LCO) 3.2.5, "Reactor Steam Dome Pressure and Core Flow", and corresponding Bases

• Replaces references to SL 2.1.1.1 in Bases section B 3.3.1.1, "Average Power Range Monitor Neutron Flux-High, Setdown"

• Eliminates tie to SL 2.1.1.1 in Bases section B 3.3.6.1 for MSL pressure low 11

Proposed Solutions/Advantages and Disadvantages ProDosed Solution #1 Advantages J..

• Simple

• No changes necessary to NUREG TS or to plant specific TS l No changes necessary to longstanding TS SLs OWNERS' GROUP 12

., .. w ... . .

Proposed Solutions/Advantages and Disadvantages Proposed Solution #1 Disadvantages

- TS Applicability unchanged

• No precedents for qualifying a TS Applicability in the Bases OWNERS' GROUP 13

Proposed Solutions/Advantages and Disadvantages e Proposed Solution #2. Advantages

• Eliminates any ambiguity with respect to Applicability of low pressure/low flow criteria OWNERS' GROUP 14

Proposed Solutions/Advantages and Disadvantages

• Proposed Solution #2 Disadvantages

• A more complex change, will require extensive re-formatting, re-numbering and re-writing of existing TS and Bases

• Requires each utility to submit a plant specific Technical Specifications change to NRC AM 15

Schedule

• Subcommittee will present their proposed TS/Bases solution to the full TSICC at the December full committee meeting

• Assuming TSICC approval, work will begin to initiate and generate a TSTF

• Tentative schedule is to submit to NRC by June, 2006. Either proposed solution will require NRC review and approval 16

Discussion Discussion! Questions / Comments 0 ]D0 from Participants 17