[Federal Register Volume 61, Number 227 (Friday, November 22, 1996)]
[Notices]
[Pages 59469-59472]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-29898]
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NUCLEAR REGULATORY COMMISSION
[Dockets Nos. 50-335 and 50-389]
Florida Power & Light Co., St. Lucie, Units 1 and 2; Issuance of
Director's Decision Under 10 CFR 2.206
Notice is hereby given that the Director, Office of Nuclear Reactor
Regulation, has taken action with regard to a Petition for action under
10 CFR 2.206 dated June 12, 1996, by Mr. Thomas J. Saporito, Jr. and on
behalf of the National Litigation Consultants. The Petition pertains to
St. Lucie, Units 1 and 2.
The Petitioners requested the Commission (1) to issue a
confirmatory order requiring that the Florida Power and Light Company
(Licensee) not operate the St. Lucie Nuclear Station, Unit 1 above 50%
of its power level
[[Page 59470]]
capacity, (2) to require the Licensee to specifically identify the
``root cause'' for the premature failure of the steam generator tubing,
and (3) to require the Licensee to specifically state what corrective
measures will be implemented to prevent recurrence of steam generator
tube failures in all the steam generators in Unit 1 and Unit 2.
The Director of the Office of Nuclear Reactor Regulation has
determined to deny the Petition. The reasons for this denial are
explained in the ``Director's Decision Pursuant to 10 CFR 2.206'' (DD-
96-19), the complete text of which follows this notice, and is
available for public inspection at the Commission's Public Document
Room, the Gelman Building, 2120 L Street, NW., Washington, DC.
A copy of the Decision will be filed with the Secretary of the
Commission for the Commission's review in accordance with 10 CFR
2.206(c) of the Commission's regulations. As provided by this
regulation, the Decision will constitute the final action of the
Commission 25 days after the date of issuance unless the Commission, on
its own motion, institutes a review of the Decision within that time.
Dated at Rockville, Maryland, this 18th day of November 1996.
For the Nuclear Regulatory Commission.
Frank J. Miraglia, Jr.,
Acting Director, Office of Nuclear Reactor Regulation.
Director's Decision Under 10 CFR 2.206
I. Introduction
On June 12, 1996, Mr. Thomas J. Saporito, Jr., on behalf of himself
and the National Litigation Consultants (Petitioners), filed a Petition
with the U.S. Nuclear Regulatory Commission (NRC or Commission)
pursuant to 10 CFR 2.206. The Petitioners requested the Commission (1)
to issue a confirmatory order requiring that the Florida Power & Light
Company (FP&L or licensee) not operate St. Lucie Plant, Unit 1, above
50 percent of its power-level capacity, (2) to require the Licensee to
specifically identify the ``root cause'' for the premature failure of
the steam generator tubing, and (3) to require the licensee to
specifically state what corrective measures will be implemented to
prevent recurrence of steam generator tube failures in all the steam
generators in Unit 1 and Unit 2.
The Petitioners' requests are based on assertions that (1) the
licensee's Unit 1 steam generator tubes have degraded to the extent
that more than 2,500 of the tubes have been plugged, (2) the licensee
has not identified the root cause for the premature failure of the
steam generator tubing, (3) the licensee will most likely experience
similar tube ruptures on other steam generators at the station, and (4)
the licensee's ``FSAR's [Final Safety Analysis Reports] and the NRC's
CFR's [Code of Federal Regulations] require that the integrity of the
primary systems on Unit 1 and Unit 2 not be breached.
The Petition has been referred to my office pursuant to 10 CFR
2.206 of the Commission's regulations. By letter dated July 8, 1996, an
acknowledgement of receipt of the Petition was sent to the Petitioners.
In that letter, the Petitioners were informed that the NRC would take
appropriate action within a reasonable time. I have completed my
evaluation of the matters raised by the Petitioners and have determined
that, for the reasons stated below, the Petition is denied.
II. Discussion
The NRC staff's evaluation of the Petitioners' requests follows.
(a) Issue a confirmatory order requiring that the licensee not
operate Unit 1 above 50 percent of its power-level capacity.
In a meeting held at NRC Headquarters on July 3, 1996, the licensee
presented the inspection and repair history for the Unit 1 steam
generator tubes.1 The licensee has performed 15 inspections since
commercial operation began in December 1976. For the most recent
inspection, completed in June 1996, the licensee inspected the full
length of all active tubes using a bobbin coil.2 In addition, the
licensee used a motorized rotating pancake coil 3 (MRPC) to
inspect all expansion transition joints and drilled support
intersections in the hot and cold legs, all free-span locations having
bobbin coil indications,4 and free-span tube regions in the upper
two support areas in the hot legs. The inspection was based on the
Electric Power Research Institute (EPRI) report ``PWR Steam Generator
Examination Guidelines,'' dated November 1992. Defective tubes having
circumferential indications, axial indications, or volumetric
indications 5 were plugged and removed from service.
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\1\ NRC Meeting Summary, Subject: ``Steam Generator Inspection,
Repair and Operating Issues--St. Lucie Unit 1,'' dated July 16,
1996.
\2\ The bobbin coil is used for a general screening of tubes for
indications of possible defects, while the motorized rotating
pancake coil (MRPC) probe is used to further characterize bobbin
coil indications. The MRPC is also used to inspect regions
susceptible to circumferentially orientated degradation.
\3\ See note 2.
\4\ See note 2.
\5\ Circumferential indications are crack-like indications
orientated on the diameter of the tube. Axial indications are crack-
like indications orientated on the long axis of the tube. Volumetric
indications are areas of general reduction in tube wall thickness
with no specific orientation.
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Including tubes plugged during earlier outages, 2,159 of 8,519
tubes (25.3 percent) in the ``A'' steam generator and 1,834 of 8,519
tubes (21.5 percent) in the ``B'' steam generator have been plugged and
removed from service. The licensee performed an evaluation that showed
that the plant could be safely operated at full power with the reduced
reactor coolant flow resulting from the increased number of plugged
tubes.6 The NRC reviewed the licensee's evaluation and concluded
that it was acceptable and that the units could be operated at full
power. The staff's evaluation is documented in a safety evaluation
dated July 9, 1996.
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\6\ FP&L letter, ``Thermal Margin and RCS Flow Limits,'' dated
June 1, 1996.
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In the meeting on July 3, 1996, the licensee presented a
preliminary run-time analysis for Unit 1, which was used to determine
the length of steam generator operation before the need for further
tube inspections to ensure adequate tube integrity. The licensee stated
that the preliminary results of its analysis support a tube inspection
interval of 15 months for the current Unit 1 cycle that started in July
1996. The licensee also stated that in situ pressure testing of the
steam generator tubes during the spring 1996 outage indicated that the
most severely degraded tubes had adequate structural integrity and
satisfied the safety margins in NRC's Regulatory Guide 1.121, ``Bases
for Plugging Degraded PWR Steam Generator Tubes.'' On the basis of the
results of the in situ pressure tests, the staff concluded that
adequate assurance of tube integrity existed to allow operation pending
completion of the licensee's run-time analysis. The NRC is currently
reviewing the licensee's analysis, which was submitted October 24,
1996.
The plant Technical Specifications for each of the units specify
leakage limits for the reactor coolant pressure boundary, including
steam generator tube leakage. If a tube leaks beyond the allowed
limits, the unit must be shut down. The plant off-normal operating
procedures for St. Lucie Units 1 and 2 also include criteria for
shutdown based on EPRI TR-104788, ``PWR Primary to Secondary Leak
Guidelines,'' dated May 1995, which are more conservative than the
limits in the plant Technical Specifications. Finally, if a tube fails,
the plant's Emergency Operating Procedures contain the specific actions
necessary for the operators to shut down
[[Page 59471]]
and cool down the plant to mitigate the consequences of the event.
Thus, as required, the licensee has implemented measures for both
units to protect public health and safety in the unlikely event that
tube integrity is compromised. These measures include a primary-to-
secondary leakage monitoring program and emergency operating
procedures. The leakage monitoring program provides early warning of
tube leakage. The steam generator blowdown monitor and condenser air
ejector monitor at each of the units continuously monitors the
radioactivity level in the main steamline. A significant increase in
the instrument readings, which would result from a relatively small
tube leak, will cause an alarm to alert the operators to the change in
radioactivity levels and potential tube leakage.
On the basis of the information submitted, the NRC staff has
concluded that the operation of the Unit 1 steam generators at full
power poses no undue risk to public health and safety.
(b) Require the licensee to specifically identify the ``root
cause'' for the premature failure of the steam generator tubing.
It is not clear how the Petitioners define ``premature failure'';
however, since there have not been any steam generator tube ruptures at
St. Lucie Units 1 or 2, it is assumed the reference is to tube
degradation. Many of the tubes in the Unit 1 steam generators have
degraded as a result of corrosion and/or mechanical conditions. The
root cause of tube degradation in steam generators is the interaction
of water chemistry, thermal-hydraulic design, materials selection,
fabrication methods, and operating conditions. The causes of tube
degradation are well understood by the industry and are documented in
the public record. The root causes for the St. Lucie steam generator
tube degradations were presented to the NRC staff in a meeting on
August 27, 1986.7
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\7\ NRC Meeting Summary, Subject: ``Summary of August 27, 1986
Meeting with FP&L and NRC Staff Regarding Steam Generator Tube
Degradation Mechanism,'' dated September 12, 1986.
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The licensee has identified to the NRC modes of degradation that
have affected the steam generator tubes in both St. Lucie Units 1 and 2
in its response of June 23, 1995, to NRC Generic Letter 95-03,
``Circumferential Cracking of Steam Generator Tubes,'' and in the
meeting of July 3, 1996. The degradation modes identified include
intergranular attack, stress-corrosion cracking and denting.
Intergranular attack refers to localized attack at and adjacent to
grain boundaries of tube material, with relatively little corrosion of
the grains. Intergranular stress-corrosion cracking refers to cracking
caused by the simultaneous presence of stress and a specific corrosive
medium. Denting is the accumulation of corrosion products at the tube-
to-tube support plate that causes plastic deformation of the tube. The
licensee has identified locations of these degradations in the tubes
during the most recent steam generator inspection of St. Lucie Unit
1.8 They include egg crate and drilled tube support plates, free
spans, expansion transition regions, and sludge pile areas. In every
case, the root cause of tube degradation can be attributed to material
selection, water chemistry, fabrication methods, or residual stresses
at the affected location.
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\8\ See note 1.
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The staff concludes that the licensee understands and has
identified the root cause of tube degradation at St. Lucie Units 1 and
2.
(c) Require the licensee to specifically state what corrective
measures will be implemented to prevent recurrence of steam generator
tube failures in all the steam generators in Unit 1 and Unit 2.
As previously discussed, degradation of the steam generator tubing
is caused by the interaction of water chemistry, thermal-hydraulic
design, materials selection, fabrication methods, and operating
conditions. The licensee has applied corrective measures in order to
reduce the rate of tube degradation. For example, the rate of tube
degradation may be reduced through improvements in water chemistry. The
licensee follows industry guidelines 9 on secondary water
chemistry for both units, and these guidelines represent a significant
improvement over the guidelines followed when Unit 1 began operating.
The guidelines have stringent requirements and limitations on specific
types and amounts of chemicals in the primary and secondary water to
mitigate corrosion. Replacement steam generators having improved
design, for example, better material selection and tube support
configuration, have had much better operating experience than the
earlier steam generators, such as those at St. Lucie. The licensee
plans to replace the Unit 1 steam generators in October 1997 with steam
generators that incorporate these design improvements.
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\9\ FP&L letter, ``Generic Letter 95-03 Response,'' dated June
23, 1995.
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The NRC staff focuses on ensuring adequate tube integrity by
requiring licensee compliance with applicable regulations and Technical
Specification requirements. The staff uses its field inspections,
meetings with the licensee, and licensing reviews to ensure that the
licensee satisfies the regulations 10 and plant Technical
Specifications as they apply to steam generator tube integrity and that
appropriate inspection methods and repair criteria are used to address
specific forms of degradation. Plant Technical Specifications define
degraded and defective tubes, specify the scope of inspections and
reporting requirements and set forth tube plugging criteria and limits
for allowable leakage in the reactor coolant system. NRC regulations
and plant Technical Specifications require that steam generator tube
degradation be managed through a combination of inservice inspection,
repair of tubes exceeding the plugging criteria in the plant Technical
Specifications, primary-to-secondary leakage monitoring, and structural
and run-time analyses to ensure that safety objectives are met. On the
basis of the information provided by the licensee in the meeting on
July 3, 1996, and the staff's onsite inspection, the staff has
concluded that the licensee is in compliance with these requirements.
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\10\ The NRC regulations that require steam generator tube
integrity be maintained include 10 CFR Part 50, Appendix A, General
Design Criteria for Nuclear Power Plants, Criterion 1--Quality
Standards and Records, Criterion 14--Reactor Coolant Pressure
Boundary, Criterion 30--Quality of Reactor Coolant Pressure
Boundary, Criterion 31--Fracture Prevention of Reactor Coolant
Pressure Boundary, and Criterion 32--Inspection of Reactor Coolant
Pressure Boundary; 10 CFR Part 50, Appendix B, Quality Assurance
Criteria for Nuclear Power Plants and Fuel Reprocessing Plants; and
10 CFR Part 50.55a, which specifies codes and standards for nuclear
power plants.
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In summary, the licensee's corrective measures to reduce the rate
of steam generator tube degradation and continued compliance with NRC
regulations and plant Technical Specification requirements provide
reasonable assurance that steam generator tube integrity at St. Lucie
Units 1 and 2 will be maintained.
III. Conclussion
On the basis of the fact that (1) the licensee has performed
adequate steam generator tube inspections that identified areas of
degradation, (2) the licensee has completed analyses and repairs of
degraded tubes, (3) the licensee's in situ pressure testing of degraded
tubes indicated adequate structural integrity remains, (4) the licensee
is monitoring primary-to-secondary leakage on a continuing basis, and
(5) the licensee is complying with NRC regulations and plant Technical
Specifications, I have concluded that a confirmatory order limiting St.
Lucie Unit 1 to 50 percent of its power-level capacity is not warranted
and that the
[[Page 59472]]
licensee has identified the root cause of tube degradation and
implemented adequate corrective measures to provide reasonable
assurance that steam generator tube integrity will be maintained at St.
Lucie Units 1 and 2.
For the reasons previously discussed, no basis exists for taking
any further action in response to the Petition. As provided in 10 CFR
2.206(c), a copy of the Decision will be filed with the Secretary of
the Commission for the Commission's review. This Decision will
constitute the final action of the Commission 25 days after issuance
unless the Commission, on its own motion, institutes a review of the
Decision within that time.
Dated at Rockville, Maryland, this 18th day of November 1996.
For the Nuclear Regulatory Commission.
Frank J. Miraglia, Jr.,
Acting Director, Office of Nuclear Reactor Regulation.
[FR Doc. 96-29898 Filed 11-21-96; 8:45 am]
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