ML053540344

Submittal of Power Point Presentation Proposed Solutions to Part 21 on Safety Limit 2.1.1.1, NUREG-1433/34

ML053540344
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
References
NUREG-1433, NUREG-1434
Download: ML053540344 (17)

Text

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

O Ozzie Vidal, Principal Engineer G Southern Nuclear Operating Company Plant Hatch December 12, 2005 1

Introduction and Purpose Presentation Overview of SL 2.1.1.1 Part 21 Description Evaluation Subcommittee Proposed Solutions Descriptions Advantages and Disadvantages Schedule Discussion 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 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% 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 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 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 6

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 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

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 Proposed Solution #1, Advantages Simple No changes necessary to NUREG TS or to plant specific TS No changes necessary to longstanding TS SLs 12

Proposed Solutions/Advantages and Disadvantages Proposed Solution #1, Disadvantages TS Applicability unchanged No precedents for qualifying a TS Applicability in the Bases 13

Proposed Solutions/Advantages and Disadvantages Proposed Solution #2, Advantages Eliminates any ambiguity with respect to Applicability of low pressure/low flow criteria 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 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 from Participants 17