ML17255A840

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Full Action Request Report AR 792213792213 MSLB Calc. Energy Release Error, Redacted
ML17255A840
Person / Time
Site: Byron  Constellation icon.png
Issue date: 06/30/2008
From:
Exelon Generation Co
To:
Office of Nuclear Reactor Regulation
Shared Package
ML17255A838 List:
References
RS-17-119 AR 792213792213
Download: ML17255A840 (4)
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Text

Go Back Print l New Search l Home AR Number: 00792213 Linked ARs Aff Fac:

Byron AR Type:

CR Status:

COMPLETE Aff Unit:

00 Owed To:

A8852CAP Due Date:

07/30/2008 Aff System:

MS Event Date:

06/30/2008 CR Level/Class:

4/D Disc Date:

06/30/2008 How Discovered:

H02 Orig Date:

06/30/2008 Action Request Details

Subject:

MSLB CALC ENERGY RELEASE ERROR

==

Description:==

Originator:

Supv Contacted:

Condition

Description:

During the EC 371293 evaluation, an error was discovered in the Unit 1 main steam line break outside containment energy release calculation. With the Replacement Steam Generators (RSG), Framatome provided the Mass and Energy (M&E) release calculations which were used as input to the Reference 1 RSG containment evaluation and Main Steam (MS) tunnel evaluations in Appendix B of Reference 2. In EC 371293 it was concluded that the energy release edits used in Reference 2 for Unit 1 were thermodynamic internal energy, not the required edit for enthalpy.

The Reference 2 calculation did not document an evaluation for power uprate. The Reference 1 Framatome calculation was analyzed for 102% of 3411 MWt down to 30% of 3411 MWt for a steam line break inside containment. B/B units 1 and 2 are currently licensed to 3586.6 MWt.

Reference 1 was analyzed to a conservative initial SG pressure of 1131.5 psia which covers the current full power pressure. Hot zero power has higher SG pressure and larger initial water inventory in the SG than full power which was also not evaluated, although it may be non-limiting for peak steam line tunnel pressure depending on the assumptions used.

Therefore, the Reference 2 M&E used for Unit 1 had several items that need re-evaluation and documentation with respect to the current design basis M&E for the short term of a steam line break outside containment.

In addition, while comparing M&E tables in the UFSAR with the M&E tables in Reference 2, it was noticed that the UFSAR Tables 6.2-50 and 6.2-50a have a typo listing Energy Rate units as "(MBtu/Lbm)" when the values shown should have been labeled "(MBtu/sec)."

References:

1.FTI Document 32-1239267-00, RSG Evaluation of MSLB inside Containment with CONTEMPT and associated M&E transmittal FTI 32-1258100-00 (SUPERSEDED WITH WESTINGHOUSE POWER UPRATE CONTAINMENT CALC) 2.Design Analysis #3C8-0282-0001, Rev. 3, "Main Steam Tunnel Pressure Study for Main Steam Line Break."

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Immediate actions taken:

EC 371293 determined best estimate M&E releases for 3586.6 MWt current full power operability under ATI 790428-02. Informed Byron & Braidwood Design Engineering Supervisor and Corporate Design Engineering Supervisor of issue. Byron & Braidwood engineering already had S&L perform an immediate operability evaluation basis under ATI 790428-02 which included the EC 371293 corrected M&E tables.

Recommended Actions:

1.Byron & Braidwood engineering to have Westinghouse or others perform a re-constituted calculation to support a corrected M&E input table and main steam line tunnel pressure calculation to replace 3C8-0282-0001 including power uprate and hot zero power evaluation.

2.Byron & Braidwood regulatory assurance to correct typos in next UFSAR update for Tables 6.2-50 and 6.2-50a to have Energy Rate units labeled

"(MBtu/sec)."

3.Byron & Braidwood engineering to perform a DCR type EC for revisions to the Reference 2 calculations with the new M&Es and power uprate evaluation.

What activities, processes, or procedures were involved?

Corporate performing of EC 371293 to support ATI 790428-02 What are the consequences?

Analytical Unit 1 Main Steam tunnel pressure will increase under steam line break conditions when the error is corrected. There is a consequence to revise calculations.

List of knowledgeable individuals:

Operable Basis:

The issues for the calculation error will need to be addressed/revised as part of Operability Evaluation.

The structure is currently operable based on preliminary assessments of the available margin for the flood seal covers.In addition EC 371278 has been installed on the U1 Aux feed flood seals to provide additional margin to failure.

Reportable Basis:

Does not meet any threshold for reporting.

SOC Reviewed by:

07/03/2008 09:31:53 CDT SOC Comments:

Braidwood actions are tracked by Braidwood IR 792215 on the same subject.

Send to Design Engineering for Action to address the Byron recommended actions in the IR. - (

7/1) SOC 070308 Reviewed by:

07/02/2008 04:28:28 CDT Reviewer Comments:

The MSLB calculation errors need to be revised to reflect power uprate and the station continues to perform EC to improve margin. Operability and reportability have been addressed. Shift review colosed.

Reviewed by:

07/02/2008 08:21:53 CDT Reviewer Comments:

Additional operability basis information added based on EC 371278 installation.

Reviewed by:

07/03/2008 03:56:54 CDT Reviewer Comments:

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Peer shift review for operability and reportability complete.

Department review performed by:

07/09/2008 11:48:15 CDT Evaluation Comments:

SOC stated: "Send to Design Engineering for Action to address the Byron recommended actions in the IR."

Action(s): The issue identified in this IR is addressed in Op Eval 07-006, Rev. 3 (EC 366685, Rev. 3). At the time that Rev. 3 of the Op Eval was written, it was not clear exactly what actions might need to be taken to resolve the issue. Therefore, CA #11 (ATI 653093-13) was written to "Determine course of action to align the physical plant and the licensing basis. (analysis, physical changes, UFSAR/licensing changes etc). Create additional actions as required." The mass & energy release issue identified in this IR 792213) must be resolved as part of the resolution of Op Eval 07-006. I have added the following to the the CA assignment in PassPort, just to be sure: "(Note: Ensure that the Mass &

Energy issue in IR 792213 is included.)" Therefore, no actions are necessary under this IR (792213).

07/09/08 Manager review performed by:

07/14/2008 05:59:45 CDT Manager Comments:

I have reviewed and approve the evaluation (for actions only).

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Assign #: 01 AR #: 00792213 Aff Fac:

Byron Assign Type:

TRKG Status:

COMPLETE Priority:

Assigned To:

Due Date:

07/18/2008 Schedule Ref:

Prim Grp:

ACAPALL Orig Due Date:

Unit Condition:

Sec Grp:

Assignment Details Subject/Description: MSLB CALC ENERGY RELEASE ERROR Assignment Completion In Progress Notes:

Completion Notes:

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