Text

Revised Schedule for Response to Generic Letter 2003-01 Control Room Habitability
	ML053180074
Person / Time
Site:	Hatch
Issue date:	11/10/2005
From:	Sumner H; Southern Nuclear Operating Co
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	GL-03-001, NL-05-2002
	Download: ML053180074 (3)
	v • d • e

H. 1. Sumner, Jr. Southern Nuclear Vice President Operating Company. Inc.

Hatch Project Post Office Box 1295 Birmingham. Alabama 35201 Tel 205.992.7279 November 10, 2005 Energy to Serve Your WorldSM DocketNos.: 50-321 NL-05-2002 50-366 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-000 1 Edwin I. Hatch Nuclear Plant Revised Schedule for Resuonse to Generic Letter 2003-01 Control Room Habitability Ladies and Gentlemen:

By letters dated August 4,2003, March 29,2004, and October 27,2004, Southern Nuclear Operating Company (SNC) submitted a course of action, including a schedule and associated justification, for developing responses to Generic Letter (GL) 2003-01, "Control Room Habitability" information requests for the Edwin I. Hatch Nuclear Plant (HNP). By letter dated September 7,2005, the NRC responded requesting fiuther changes to the current SNC schedule for responding to GL 2003-01.

SNC has requested a meeting with NRC staff to discuss the interim basis for 10 CFR 50 Appendix A General Design Criterion (GDC) 19 conformance during and potentially following ASTM E74 1 tracer gas testing prior to receipt of NRC approval for implementation of an alternative source term (AST) in accordance with 10 CFR 50.67.

Provided regulatory issues related to the interim use of potassium iodide and non-standard occupancyhreathing rate models can be satisfactorily addressed and the appropriate test vendor support can be obtained, every effort will be made to conduct testing as expeditiously as possible. Within 90 days after the completion of the HNP tracer gas testing, SNC will submit the information requested by GL 2003-01.

During the requested meeting, SNC intends to propose a change to the Hatch licensing basis that would allow for crediting of potassium iodide to meet 10 CFR 50 Appendix A GDC 19 requirements for an interim time period.

In preparation for the requested meeting, a November 4,2005 telephone conference was conducted between NRC staff and SNC personnel. During this telecon SNC discussed, in more detail than in previous telecons, the preliminary results of a bounding HNP operability determination of control room unfiltered inleakage, developed consistent with NRC guidance contained in the NRC letter dated January 30,2004, from Mr. Eric Leeds, NRR to Mr. James Davis, Nuclear Energy Institute (NEI) in response to a draft NEI white paper on control room habitability.

U. S. Nuclear Regulatory Commission NL-05-2002 Page 2 During the November 4, 2005 telecon, details related to the unique location of the HNP Unit 1 and 2 common control room were discussed. The control room, as part of the control building, is located between the open end bays of the Units 1 and 2 turbine buildings. The majority of the ductwork associated with the Main Control Room Environmental Control System, which encompasses two independent filter trains for pressurizing the control room post-accident, is located external to the control room boundary on top of the control building within the confines of the HNP Unit 1 and 2 turbine buildings. Consequently, post-accident radiological releases within the turbine building, such as to the main steam lines, secondary containment bypass paths, and the main condenser, as well as releases into the turbine building itself, become controlling factors in the analysis of 3 of the 4 Hatch design basis accidents (DBAs), specifically the loss-of-coolant accident (LOCA), main steam line break accident (MSLB), and control rod drop accident (CRDA).

The HNP current licensing basis control room inleakage is 0 cfm based on having a pressurized control room. While preparing for planned HNP tracer gas testing in October, 2004, later cancelled due to issues with the use of potassium iodide raised by the NRC, SNC explored the use of an operability determination based on the TID source term and RG 1.195 guidance. Only minimal control room inleakage can be justified without the use of potassium iodide or self-contained breathing apparatus (SCBA).

Application of AST analytical methods, consistent with the previously referenced NRC letter dated January 30,2004, will justify approximately 60 cfm control room inleakage (of which 10 cfm is allocated for ingresdegress). Consistent with NRC RIS 2005-20 guidance, the following key compensatory measures would have to be used for the duration that the operability determination is in place.

For LOCA only, a main steam isolation valve alternate leakage treatment path is credited for HNP Unit 1; NRC approved previously for HNP Unit 2.

For LOCA only, the standby liquid control system is credited to buffer the suppression pool preventing iodine re-evolution.

For LOCA only, drywell spray is credited.

For LOCA, MSLB, and CRDA, the HNP Units 1 and 2 existing turbine building ventilation systems are credited with purging the area around the control room.

During the November 4, 2005 telecon, the use in the operability determination of more realistic assumptions than those contained in RG 1.183 guidance for control room occupancyhreathing rates and engineered safety feature (ESF) leakage was suggested.

Since the ESF leakage is mitigated by processing though the standby gas treatment system filters with an elevated release point, a more realistic value will have little impact on the allowable control room inleakage. A more realistic value for the control room occupancy/breathing rates is anticipated to improve the allowable inleakage to approximately 100 cfm for the LOCA since the radiological release associated with a LOCA lasts over a 30 day period. However, since the radiological releases associated with the MSLB and CRDA have a much more limited duration of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , not much improvement in allowable control room inleakage is expected for those DBAs. Finally,

U. S. Nuclear Regulatory Commission NL-05-2002 Page 3 the use of additional shielding has been assessed to not be of significant value since the radiological releases at issue in the turbine building are airborne.

Since SNC has completed control room boundary maintenance in 2004, the measured unfiltered inleakage from HNP tracer gas testing is expected to be low. However, it would not be prudent for SNC to proceed with testing without planned measures in place should testing show control room inleakage higher than approximately 100 cfm. It is for this reason that SNC has requested a meeting to facilitate the resolution of any issues associated with incorporation of potassium iodide into the licensing basis, and any other issues associated with conducting HNP tracer gas testing prior to the NRC approval of AST.

Ultimate resolution of the control room habitability issue for HNP is dependant on NRC approval for full scope implementation of an AST in accordance with 10 CFR 50.67.

Currently submittal of AST is targeted for as early as possible in the first quarter of 2006.

This letter contains no NRC commitments. If you have any questions, please advise.

Sincerely, cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. G. R. Frederick, General Manager - Plant Hatch RTYPE: CHA02.004 U. S. Nuclear Reaulatorv Commission Dr. W. D. Travers, Regional Administrator Mr. C. Gratton, NRR Project Manager - Hatch Mr. D. S. Simpkins, Senior Resident Inspector - Hatch