ML081200435

Facility Post - Examination Comments for the Fermi Initial Exam - January 2008

ML081200435
Person / Time
Site:	Fermi
Issue date:	03/25/2008
From:	Hironori Peterson Operations Branch III
To:	Jennifer Davis Detroit Edison
Shared Package
ML080860174	List: ML081190547 ML081190699 ML081190701 ML081190704 ML081190707 ML081200422 ML081200435 ML081200448 ML081200455
References
50-341/08-301
Download: ML081200435 (4)

Text

FACILITY POST-EXAMINATION COMMENTS FOR THE FERMI INITIAL EXAM -JANUARY 2008

DTE Energy February 7,2008 NRC-08-0019 Mr. Michael E. Bielby Region 111 U. S. Nuclear Regulatory Commission 2443 Warrenville Road, Suite 210 Lisle. Illinois 60532-4352

Dear Mr. Bielby:

Please find enclosed the following post-examination materials for the Fermi 2 Initial License Examination administered January 28 through February 1,2008.

Graded written examinations including each applicants original answer and examination cover sheets.

Master SRO and RO written examinations and answer keys with a document annotating any changes made while administering and grading the examination.

A summary of the basis for two proposed changes to be made to the original written examination answer keys.

A summary of any questions asked by, and answers given to, the applicants during the written examination.

0 A summary of substantive comments made by the applicants after the written examination with an explanation why the comment was accepted or rejected.

0 The written examination seating chart.

0 A completed Form ES-403-1 Written Examination Grading Quality Assurance Checklist for the SRO and RO written examination.

0 A summary of the examination analysis results for the SRO and RO written examination.

0 A summary of general candidate comments concerning the

. examination administration process submitted for NRC consideration.

Copies of Form ES-201-3 Examination Security Agreement, as completed to date with final closeout signatures.

These materials are being submitted in accordance with the requirements of NUREG 1021, Revision 9.

FER 1 2 1008

NRC-08-0019 Region I11 February 7, 2008 Page 2 If you have any questions or comments regarding the contents of the items listed above, please contact Mr. Timothy Horan at (734) 586-4961.

Sincerely, Enclosures

Proposed Changes to Original Exam Answer Key J

Comment Q49: Answer D was listed in the key as being the correct answer. C is also correct based on the fact that Fermi 2 has a Mark 1 Containment. The Mark 1 Containment is susceptible to the phenomenon know as CHUGGING.

See Appendix B, Rev 2 of the EPGs, Page 8-7-35, for additional information regarding the following:

Following a DBA LOCA, Drywell Pressure (DW/P) would rapidly increase and force steam and non-condensable gasses from the Drywell into the Torus.

Torus Pressure would rapidly rise and exceed the Suppression Spray Initiation Pressure (SCIP), which is 9 psig for Fermi 2. Once the Torus Pressure exceeds 9 psig, the EPGs assume that a large fraction (95%) of the non-condensable gasses (nitrogen inerting the drywell) in the Drywell have been transferred to the Torus. Once this occurs, chugging becomes a primary concern.

Chugging is defined as: the repeated collapsing, and reformation, of steam bubbles at the Downcomer Vent opening. When the steam bubbles collapse at the exit of the Downcomers. the rush of water drawn into the Downcomer, to fill the void, induces severe stresses at the junction of the Downcomers and Vent Header in the Mark 1 Containments. Repeated application of such stresses could cause fatigue failure of these joints, thereby creating a direct path between the Drywell and Suppression Chamber. Steam discharged through the Downcomers could then bypass the Suppression Pool and directly pressurize the Primary Containment.

Initiating Drywell Sprays when Torus Pressure exceeds 9 psig, will cause the non-condensable gasses to be drawn back into the Drywell atmosphere, thereby preventing chugging.

With Drywell Sprays not available, (as stated in distractor C) chugging could not be prevented and containment integrity could be threatened, as described in the EPGs.

Therefore we recommend both answers be accepted.

Comment (263: Answer D was listed in the key as being the correct answer. C is also correct The term reason led the examinees to not look for the basis of the Main Steam Tunnel High Temperature Auto Isolation. The stem should have stated the auto isolation and the basis per 10CFRl00. This allowed Answer C to also be correct. Answer C is a reason to isolate MSIVs. This question originally had basis, instead of reason, in the stem. It was changed upon NRC request.

The Secondary Containment and Radioactive Release EOP purposelbasis is to protect equipment important to safety, in the Secondary Containment, to protect the integrity of the Secondary Containment, and to limit radioactivity release to and from the Secondary Containment. See attached information from SCClRR EOP Student Text.

Therefore we recommend both answers be accepted.