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Nuclear HVAC Services
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Historically, the nuclear industry has not
recognized HVAC systems as a priority. HVAC systems were
not considered vital to power production or safety
system performance. HVAC systems commonly have not been
maintained effectively and are limited by obsolescence.
HVAC systems also have not kept pace with other changes
in the plant and may be undersized for the demand loads.
More recently however, the NRC staff has placed
increased emphasis on the critical support HVAC systems
provide Engineered Safety Features (ESF) plant
functions. Generic Letter 2003-01, Control Room
Habitability, for example, highlights the staff’s
emphasis the importance ventilation systems play in the
safe operation of the plant. Other areas receiving
increasing oversight are ECCS room temperature,
containment and Spent Fuel Pool cooling, and Station
Black Out (SBO) issues.
WPE provides individuals who are recognized by the
Nuclear HVAC Utility Group (NHUG) as industry leaders in
nuclear HVAC engineering services. These services
include but are not limited to the following: |
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- HVAC Plant Systems Design Basis Reconstitution,
Programmatic and Technical Reviews
- System Upgrade Design Studies
- Control Room Habitability Programmatic,
Analytical, and Testing Support
- TSC Post LOCA Habitability Impact
- Room Heat-up Transient Analysis Following Loss
of Ventilation Scenarios
- Station Blackout (SBO) Coping Assessments Loss
of Ventilation Analyses
- HVAC System Pressure Loss Calculations to
Support System Design and Balancing
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Control Room Habitability
USNRC Generic Letter (GL) 2003-01
“Control Room Habitability" |
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Background
In addition to normal Control Room environmental
control functions, Control Room HVAC systems are
designed to limit operator dose in the event of a
radiological accident, and to minimize exposure to toxic
gases or smoke by limiting infiltration. These
objectives are accomplished by various combinations of
isolation, filtration and, in some designs,
pressurization. Clearly, the Control Room boundary must
be intact and the systems required to support Control
Room Envelope integrity must function properly to
maintain a habitable Control Room during postulated
design basis accidents.
The US Nuclear Regulatory Commission (NRC) issued
Generic Letter 2003-01 in June 2003 to address
regulatory concerns associated with Control Room
Habitability in operating nuclear power facilities. In
summary, the Generic Letter requested licensees take
actions to define the design/licensing bases for their
Control Room Habitability Systems, to perform testing
and analyses to verify the overall systems function in
accordance with the design/licensing bases, and to
implement programs and controls to ensure the systems do
not deviate from their design/licensing bases
configuration or previously tested condition.
The Nuclear Energy Institute (NEI) developed the
Control Room Habitability Guidance Document, NEI 99-03,
to assist the industry in assuring that their Control
Rooms satisfy the NRC regulations and licensee
commitments associated with their Control Room
Habitability Systems. The NRC has endorsed most of the
guidance provided in NEI 99-03 with specific exceptions
delineated in Regulatory Guides 1.196 and 1.197 which
were issued concurrent with the Generic Letter.
WPE has worked closely with several plants in
formulating a response to the issues identified in
Generic Letter 2003-01. Recent feedback from the NRC
indicates that industry response to these issues has
been varied and that many plants have not responded
adequately to the concerns of the Generic Letter. WPE’s
programs have been designed around the criteria
delineated by the Regulatory Guides and recommendations
of NEI 99-03.
Control Room Habitability Systems
Assessment
WPE has developed detailed reports summarizing the
licensing basis for Control Room Habitability Systems.
Beginning with the Final Safety Analysis Report
submitted in support of a plant’s original license
request and the Safety Evaluation Report issued by the
AEC/NRC, the assessments outline the changes to the
licensing basis through subsequent amendments and
commitments made in response to significant plant
issues. The purpose of these “vertical slice”
assessments has been twofold: they consolidate the
information contained in numerous documents developed
over many years, and they identify vulnerabilities in
the current system design and/or operation in the
context of its licensing basis.
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Seabrook, NH 03874
603-474-7477
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