[Federal Register Volume 77, Number 172 (Wednesday, September 5, 2012)]
[Notices]
[Page 54619]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-21811]



[[Page 54619]]

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NUCLEAR REGULATORY COMMISSION

[NRC-2012-0203; Docket Nos. STN 50-456, STN 50-457, STN 50-454 AND STN 
50-455; License Nos. 72, 77, 37, and 66]


Exelon Generation Company, LLC., Receipt of Request for Action

    Notice is hereby given that by petition dated April 20, 2012, Mr. 
Barry Quigley has requested that the U.S. Nuclear Regulatory Commission 
(NRC, the Commission) take action with regard to Braidwood Station, 
Units 1 and 2, and Byron Station, Units 1 and 2. The petitioner 
requests that the NRC require Exelon Generation Company, LLC (Exelon) 
to shut down immediately, Byron Station, Units 1 and 2, and Braidwood 
Station, Units 1 and 2, until all turbine building (TB) high-energy 
line break (HELB) concerns are identified and those important to safety 
are corrected.
    As the basis for this request, the petitioner states the following:
     An adequate supply of combustion air for the diesel 
generators (DG) is threatened because the combustion air can be diluted 
with steam. Although the combustion air is drawn from an air shaft (not 
the TB), it is also the same air shaft that supplies ventilation for 
the DG room. Under certain conditions, the ventilation damper alignment 
is such that steam that enters the DG room from the ventilation exhaust 
can flow back into the inlet air shaft. From there it can be drawn into 
the engine, potentially starving the engine of air.
     The effects of high temperature in the engineered safety 
feature (ESF) switchgear rooms on the protective relaying setpoints has 
not been evaluated. The concern is that high temperatures could alter 
the setpoints, causing protective actions to occur under normal loading 
conditions.
     The current method of analysis for TB HELB uses a ``lumped 
volume'' approach wherein the mass and energy of the ruptured line 
mixes instantly with the entire volume before flowing into the areas of 
concern. Since this substantially reduces the energy flow, it does not 
always give conservative results. For example, a preliminary assessment 
using the subdivided volume feature in the GOTHIC computer code shows 
that the structural limits on the block wall between the ESF switchgear 
rooms would be substantially exceeded.
     There has been no structured and detailed review of the 
licensing requirements for HELB.
    The NRC is treating this request pursuant to Title 10 of the Code 
of Federal Regulations (10 CFR), Section 2.206. The request has been 
referred to the Director of the Office of Nuclear Reactor Regulation 
(NRR). As required by Section 2.206, the NRC will take appropriate 
action on this petition within a reasonable time. The petitioner met 
with the petition review board on May 16, 2012, to discuss the 
petition. The board reviewed the information provided in that meeting 
in its consideration of the petitioner's request for immediate action 
and in establishing the schedule for the review of the petition. By 
letter dated August 23, 2012, the Director of NRR denied the 
petitioner's request for immediate shutdown of Exelon's Byron Station, 
Unit Nos. 1 and 2, and Braidwood Station, Units 1 and 2. A copy of the 
petition is available for inspection at the Commission's Public 
Document Room (PDR), located at One White Flint North, Public File Area 
O1 F21, 11555 Rockville Pike (first floor), Rockville, Maryland 20852. 
Publicly available documents created or received at the NRC are 
accessible electronically through the Agencywide Documents Access and 
Management System (ADAMS) in the NRC Library at http://www.nrc.gov/reading-rm/adams.html. Those who do not have access to ADAMS or who 
encounter problems in accessing the documents located in ADAMS should 
contact the NRC PDR reference staff by telephone at 1-800-397-4209 or 
301-415-4737, or by email to [email protected].

    Dated at Rockville, Maryland, this 23rd day of August 2012.

    For the Nuclear Regulatory Commission.

Eric J. Leeds,
Director, Office of Nuclear Reactor Regulation.
[FR Doc. 2012-21811 Filed 9-4-12; 8:45 am]
BILLING CODE 7590-01-P