[Federal Register Volume 62, Number 70 (Friday, April 11, 1997)]
[Notices]
[Pages 17887-17888]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-9392]


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NUCLEAR REGULATORY COMMISSION


Degradation of Control Rod Drive Mechanism Nozzle and Other 
Vessel Closure Head Penetrations; Issued

AGENCY: Nuclear Regulatory Commission.

ACTION: Notice of issuance.

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SUMMARY: The Nuclear Regulatory Commission (NRC) has issued Generic 
Letter 97-01 to notify all holders of operating licenses for 
pressurized water reactors (PWRs), except those who have permanently 
ceased operations and have certified that fuel has been permanently 
removed from the reactor vessel, of the need for information concerning 
their programs for ensuring the timely inspection of control rod drive 
mechanism (CRDM) and other vessel closure head penetrations. The 
information requested is needed by the NRC staff to verify compliance 
with 10 CFR 50.55a and 10 CFR Part 50, Appendix A, GDC 14, and to 
determine whether an augmented inspection program, pursuant to 10 CFR 
50.55a(g)(6)(ii), is required.
    The proposed generic letter is a ``rule'' for purposes of the Small 
Business Regulatory Enforcement Fairness Act (5 U.S.C., Chapter 8). The 
staff has received confirmation from the Office of Management and 
Budget that the generic letter is a non-major rule.
    This generic letter is available in the NRC Public Document Room 
under accession number 9703260336.

DATES: The generic letter was issued on April 1, 1997.

ADDRESSES: Not applicable.

FOR FURTHER INFORMATION CONTACT: C. E. Carpenter, Jr. at (301) 415-
2169.

SUPPLEMENTARY INFORMATION: The NRC staff has concluded that vessel 
closure head penetration (VHP) cracking does not pose an immediate or 
near term safety concern. In the long term, however, the degradation of 
CRDM nozzles and other VHPs is an important safety consideration that 
warrants further evaluation. The vessel closure head provides the vital 
function of maintaining reactor pressure boundary. Cracking in the VHPs 
has occurred and is expected to continue to occur as plants age. The 
NRC staff considers cracking of VHPs to be a safety concern for the 
long term based on the possibility of (1) Exceeding the American 
Society of Mechanical Engineers (ASME) Code for margins if the cracks 
are sufficiently deep and continue to propagate during subsequent 
operating cycles, and (2) eliminating a layer of defense in depth for 
plant safety. Therefore, to verify that the margins required by the 
ASME Code, as specified in 10 CFR 50.55a are met, that the guidance of 
General Design Criterion 14 of Appendix A to 10 CFR Part 50 is 
continued to be satisfied, and to ensure that the safety significance 
of VHP cracking remains low, the NRC staff believes that an integrated, 
long-term program, which includes periodic inspections and monitoring 
of VHPs, is necessary. In addition, the NRC staff finds that the 
requested information is also needed to determine if the imposition of 
an augmented inspection program, pursuant to 10 CFR 50.55a(g)(6)(ii), 
is required to maintain public health and safety. The staff is not

[[Page 17888]]

establishing a new position for compliance in this generic letter.

    Dated at Rockville, Maryland, this 3rd day of April 1997.

    For the Nuclear Regulatory Commission.
Marylee M. Slosson,
Deputy Director, Division of Reactor Program Management, Office of 
Nuclear Reactor Regulation.
[FR Doc. 97-9392 Filed 4-10-97; 8:45 am]
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