[Federal Register Volume 61, Number 194 (Friday, October 4, 1996)]
[Notices]
[Page 52069]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-25488]



[[Page 52069]]

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NUCLEAR REGULATORY COMMISSION

Assurance of Equipment Operability and Containment Integrity 
During Design-Basis Accident Conditions; Issued

AGENCY: Nuclear Regulatory Commission.

ACTION: Notice of issuance.

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SUMMARY: The Nuclear Regulatory Commission (NRC) has issued Generic 
Letter 96-06 to notify all licensees of nuclear power reactors about 
several safety-significant issues that have been identified as a result 
of recent NRC inspection activities, licensee notifications, and event 
reports, and that warrant action by the NRC to assure that they have 
been adequately addressed and resolved; these issues include:
    (1) Cooling water systems serving the containment air coolers may 
be exposed to the hydrodynamic effects of waterhammer during either a 
loss-of-coolant accident (LOCA) or a main steamline break (MSLB). These 
cooling water systems were not designed to withstand the hydrodynamic 
effects of waterhammer and corrective actions may be needed to satisfy 
system design and operability requirements.
    (2) Cooling water systems serving the containment air coolers may 
experience two-phase flow conditions during postulated LOCA and MSLB 
scenarios. The heat removal assumptions for design-basis accident 
scenarios were based on single-phase flow conditions. Corrective 
actions may be needed to satisfy system design and operability 
requirements.
    (3) Thermally induced overpressurization of isolated water-filled 
piping sections in containment could jeopardize the ability of 
accident-mitigating systems to perform their safety functions, and 
could also lead to a breach of containment integrity via bypass 
leakage. Corrective actions may be needed to satisfy system operability 
requirements.
    This generic letter requests that licensees determine the 
susceptibility of their facility containment air cooler cooling water 
systems to either waterhammer or two-phase flow conditions during 
postulated accident conditions, determine the susceptibility of piping 
systems that penetrate the containment to thermal expansion of fluid 
and overpressurization, and assess the operability of affected systems 
and take corrective action, as appropriate to satisfy system design and 
operability requirements. Licensees are also required to submit a 
written response. This generic letter is available in the NRC Public 
Document Room under accession number 9609250096.

DATES: The generic letter was issued on September 30, 1996.

ADDRESSEES: Not applicable.

FOR FURTHER INFORMATION CONTACT: James E. Tatum at (301) 415-2805.

SUPPLEMENTARY INFORMATION: The actions requested in this generic letter 
are considered compliance backfits under the provisions of 10 CFR 
50.109 and existing NRC procedures to ensure that containment integrity 
is maintained, that safety-related components and piping systems are 
capable of performing their intended safety functions and satisfying 
their licensing-basis code criteria, respectively, and that containment 
integrity and safety-related piping systems and components are not 
adversely affected by the occurrence of waterhammer, two-phase flow, or 
thermal overpressurization that may occur in safety-related and non-
safety-related systems that penetrate containment.

    Dated at Rockville, Maryland, this 30th day of September, 1996.

    For the Nuclear Regulatory Commission.
Brian K. Grimes.
Acting Director, Division of Reactor Program Management, Office of 
Nuclear Reactor Regulation.
[FR Doc. 96-25488 Filed 10-3-96; 8:45 am]
BILLING CODE 7590-01-P