[Federal Register Volume 61, Number 229 (Tuesday, November 26, 1996)]
[Notices]
[Pages 60124-60126]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-30155]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-309]
Maine Yankee Atomic Power Company; Maine Yankee Atomic Power
Station; Issuance of Director's Decision Under 10 CFR 2.206
Notice is hereby given that the Acting Director, Office of Nuclear
Reactor Regulation, has acted on a Petition for action under 10 CFR
2.206 received from Ms. Anne D. Burt, on behalf of Friends of the
Coast--Opposing Nuclear Pollution, dated January 20, 1996, for the
Maine Yankee Atomic Power Station.
The Petition requests that the Commission take expedited action to
(1) suspend the operating license of Maine Yankee pending resolution of
the Petition; (2) examine and test by plug sampling--or other methods
approved by the American Society of Mechanical Engineers--all large
piping welds that may have been susceptible to micro-fissures at the
time of construction; (3) reanalyze the Maine Yankee containment as one
located in an area where seismic risk is not ``low''; (4) reduce the
licensed operating capacity of Maine Yankee to a level consistent with
a flawed containment and/or flawed reactor coolant piping welds; (5)
hold an informal public hearing in the area of the plant regarding the
Petition; and (6) place the Petitioner on service and mailing lists
relevant to the group's interests in safety at Maine Yankee and
intention to participate in all public forums opened by the Nuclear
Regulatory Commission (NRC).
By letter dated May 13, 1996, the Director, Office of Nuclear
Reactor Regulation (NRR), NRC, acknowledged the NRC's receipt of the
Petition, and, for the reasons stated in the letter, denied
Petitioner's request for immediate action suspending the operating
license or reducing the licensed operating capacity of Maine Yankee
(Requests 1 and, in part, 4). In addition, for reasons stated in the
May 13, 1996, letter, the Director denied the Petitioner's request for
an informal hearing (Request 5). The Director also stated in the May
13, 1996, letter that Petitioner's request that the NRC place
Petitioner on service and mailing lists relevant to its interests in
safety at Maine Yankee and its intention to participate in all public
forums opened by the NRC (Request 6) was moot, as Petitioner's attorney
had already been added to the Maine Yankee service list.
The Acting Director of the Office of Nuclear Reactor Regulation has
now determined that no basis exists for taking any action in response
to Requests 2, 3, and 4 of the Petition dated January 20, 1996.
Accordingly, Requests 2, 3, and 4 have been denied for the reasons
stated in the ``Director's Decision Under 10 CFR 2.206'' (DD-96-20),
the complete text of which follows this notice and which is available
for public inspection at the Commission's Public Document Room, the
Gelman Building, 2120 L Street, N.W., Washington, D.C. 20555, and at
the local public document room located at the Wiscasset Public Library,
High Street, P.O. Box 367, Wiscasset, Maine 04578. A copy of this
Decision will be filed with the Secretary for the Commission's review
in accordance with 10 CFR 2.206. As provided by the regulation, the
Decision will constitute the final action of the Commission 25 days
after the date of issuance of the Decision unless the Commission on its
own motion institutes a review of the Decision within that time.
Dated at Rockville, Maryland, this 20th day of November 1996.
For the Nuclear Regulatory Commission.
Frank J. Miraglia,
Acting Director, Office of Nuclear Reactor Regulation.
I. Introduction
By letter dated January 20, 1996, Ms. Anne D. Burt filed a Petition
with the U.S. Nuclear Regulatory Commission (NRC), pursuant to 10 CFR
2.206, on behalf of the Friends of the Coast--
[[Page 60125]]
Opposing Nuclear Pollution (the Petitioner) requesting that actions be
taken regarding the Maine Yankee Atomic Power Station (Maine Yankee),
operated by the Maine Yankee Atomic Power Company (the licensee). The
Petition requests that the Commission take expedited action to (1)
suspend the operating license of Maine Yankee pending resolution of the
Petition; (2) examine and test by plug sampling--or other methods
approved by the American Society of Mechanical Engineers--all large
piping welds that may have been susceptible to micro-fissures at the
time of construction; (3) reanalyze the Maine Yankee containment as one
located in an area where seismic risk is not ``low''; (4) reduce the
licensed operating capacity of Maine Yankee to a level consistent with
a flawed containment and/or flawed reactor coolant piping welds; (5)
hold an informal public hearing in the area of the plant regarding the
Petition; and (6) place the Petitioner on service and mailing lists
relevant to the group's interests in safety at Maine Yankee and
intention to participate in all public forums opened by the NRC.
By letter dated May 13, 1996, the Director, Office of Nuclear
Reactor Regulation (NRR), NRC, acknowledged the NRC's receipt of the
Petition, and, for the reasons stated in the letter, denied
Petitioner's request for immediate action suspending the operating
license or reducing the licensed operating capacity of Maine Yankee
(Requests 1 and, in part, 4). In addition, for reasons stated in the
May 13, 1996, letter, the Director denied the Petitioner's request for
an informal hearing (Request 5). The Director also stated in the May
13, 1996, letter that the request that the NRC place Petitioner on
service and mailing lists relevant to its interests in safety at Maine
Yankee and its intention to participate in all public forums opened by
the NRC (Request 6) was moot, as Petitioner's attorney had already been
added to the Maine Yankee service list. In addition, the Petitioner was
informed that NRC would review the Petition in accordance with 10 CFR
2.206 and issue a final decision within a reasonable time.
The remaining specific requests for NRC action in the Petition
dated January 20, 1996, i.e., Requests 2, 3, and 4 identified above,
and the issues that Petitioner raised as their bases, are addressed in
this decision. For the reasons set forth below, Petitioner's remaining
requests for action pursuant to 10 CFR 2.206 are denied.
II. Discussion
The NRC staff has conducted a thorough evaluation of each of the
two safety-related issues raised in the Petition regarding the adequacy
of the containment and reactor coolant welds. Each of the issues is
addressed below.
a. Adequacy of Containment Design at or Above Originally Authorized
Power Level
The Petitioner asserts that the containment is inadequate for
operation at any power in excess of that authorized in the original
license, and may be inadequate for the originally licensed power level
because of insupportable original design acceptance criteria in that
the Maine Yankee containment was designed and constructed without
diagonal rods. The Petitioner states that
The Atomic Energy Commission staff recommended to the commission
that a license amendment permitting this type of construction be
allowed, ``* * * for this plant and this plant only due to low
seismic risk.'' Early in 1979 the MYAPS was shaken by an earthquake
of 4.2 magnitude and epicentered less than ten miles from the plant
site. The NRC then ordered the shutdown of five nuclear power
stations including MYAPS until piping and piping supports could be
seismically qualified * * *
The Petitioner also states that there is no public record, however,
that NRC reevaluated what Petitioner asserts is a marginally acceptable
containment design at Maine Yankee before it granted license amendments
to operate at increased power.
The Maine Yankee containment is a reinforced concrete structure.
The original NRC operating license review determined that the seismic
and thermal-hydraulic design of Maine Yankee's containment structure is
adequate. (The construction permit for Maine Yankee was issued on
October 21, 1968, and the operating license was issued on September 15,
1972.) With its Petition of January 20, 1996, the Petitioner enclosed
an NRC letter of January 22, 1971, in which the staff asked the
licensee to submit additional information related to seismic shear
stress, given that there are no diagonal seismic shear reinforcements
in the containment wall. Low seismicity of the site was not a factor in
the staff's acceptance of the Maine Yankee containment design without
diagonal seismic reinforcement bars. As described below, acceptance by
the staff of the adequacy of the seismic design was based on the
results of stress analyses.
The earthquake for which Maine Yankee was originally designed--
termed a Safe Shutdown Earthquake (SSE)--is based on a Housner design
response spectrum with a zero period peak horizontal ground
acceleration of 0.10g. The five plant shutdown that was ordered on
March 13, 1979, was triggered by a finding of an error in a piping
computer program, which led to the issuance of IE Bulletin No. 79-07,
``Piping Stress Analysis of Safety-Related Piping'' on April 14, 1979.
The earthquakes that occurred near the plant site starting on April 18,
1979, at 02 hours and 34 minutes universal time, were not a factor in
the five plant shutdown that was ordered on March 13, 1979. As a
consequence of the sequence of earthquakes that occurred near the plant
in April 1979 and the occurrence of the January 9, 1982, magnitude 5\3/
4\ earthquake in New Brunswick, Canada, the licensee undertook a
seismic analysis program. This program included analyses and upgrading
of certain plant components and a reevaluation of the seismic hazard.
Thus, the results from the seismic analyses and upgrading program were
instrumental in the staff's conclusion that the existing seismic design
for Maine Yankee remained adequate. However, following its review of
the seismic hazard reevaluation, the NRC staff determined that the
appropriate characterization of the ground motion for any future
analysis of the plant is a high-frequency peak ground acceleration of
0.18 g anchoring the response spectrum obtained from NUREG/CR-0098,
``Development of Criteria for Seismic Review of Selected Nuclear Power
Plants,'' using the 50th percentile amplification factors.
Subsequently, in 1986, the Maine Yankee Plant underwent a seismic
margin assessment program. The review-level earthquake used in the
seismic margin assessment had a peak ground acceleration of 0.3g, which
is much greater than the peak ground acceleration of the SSE. The
seismic safety margin program included a review of the entire plant
including analysis and upgrading of certain plant components, such as
Main Control Board, Control Room Auxiliary Cabinets, Service Water
Piping Support and others. As a result of this reassessment, it was
established that, with the upgrades implemented at the plant, the Maine
Yankee Plant can be safely shut down during an earthquake with a peak
ground acceleration of 0.27g.
In its report ``Seismic Margin Review of the Maine Yankee Atomic
Power Station'' (NUREG/CR-4826, Vol. 2,
[[Page 60126]]
dated March 1987), the NRC staff also concluded that the overall
seismic margin of the plant, including the containment, was well above
the 0.18g value and, therefore, no upgrading of the seismic design was
considered necessary. Further, in the staff report ``An Approach to the
Quantification of Seismic Margins in Nuclear Power Plants'' (NUREG/CR-
4334, dated August 1985), it is also noted that prestressed and
reinforced concrete containment structures have a large seismic margin
above the SSE level earthquake.
Additionally, numerous tests and studies conducted since the
operating license review of the Maine Yankee Plant, specifically on
shear stress in biaxially cracked reinforced concrete without diagonal
reinforcement bars, have led to the acceptance of specified allowable
shear stress by the American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code (Code), Section III, Division 2, CC-
3421.5, for reinforced-concrete containment structures. An analysis of
the Maine Yankee containment structure was conducted in December 1984
by the licensee and submitted on the Docket as an attachment to letter
MN-85-27, dated February 5, 1985. The results of the study indicate
that the controlling peak ground acceleration value is 0.39g for the
ASME Code allowable tangential shear stress caused by the SSE loading
in combination with design-basis internal pressure and dead loads. This
provides additional confidence on the ruggedness of the Maine Yankee
containment.
Based on the above, with regard to the Petitioner's concern about
the adequacy of the Maine Yankee containment structural design for
earthquakes (seismic), the staff concludes that the Maine Yankee
containment is satisfactory and has adequate margin. The NRC staff has
determined that the design of the Maine Yankee containment structure
without diagonal reinforcement bars is supported by analysis and poses
no undue risk to public health and safety. Accordingly, Petitioner's
requests for NRC action based on the seismic design of the containment
are denied.
b. Microfissuring of Low-Ferrite Stainless Steel Weldments
The Petitioner asserts that the Maine Yankee emergency core cooling
system (ECCS), reactor coolant piping, and other large piping have not
been adequately analyzed for materials degradation to ensure integrity
at power operation in excess of the originally licensed power level or
under accident conditions. The Petitioner states further that the
Atomic Energy Commission's concern with ``microfissures'' in reactor
coolant system welds led to the appointment of a task force, and
prompted studies and reports in 1971 (before heightened awareness of
embrittlement phenomena) that concluded that the microfissures would
not propagate or grow under foreseeable conditions. The Petitioner
asserts that large pipe welds next to the reactor vessel have endured
23 years of corrosion, stress, vibration, and radiation and may fail,
initiating a loss-of-coolant accident, or may be subject to thermal
shock failure initiated by use of the ECCS.
In a safety evaluation dated February 25, 1972, the NRC staff
concluded that the low-ferrite stainless steel weldments in large
piping at Maine Yankee are acceptable because the micro-fissures of the
type and density found in the low-ferrite stainless steel weldments of
the Maine Yankee facility do not significantly impair the strength and
capability of the welds, and that removal of the welds and rewelding
could introduce other problems of greater safety significance than
those resulting from the presence of microfissures. This evaluation was
based on information provided by Battelle Columbus Laboratories, Stone
and Webster Engineering Corporation, and Dr. Ernest F. Nippes of
Rensselaer Polytechnic Institute. Furthermore, the Maine Yankee reactor
vessel meets the requirements of 10 CFR 50.61, ``Fracture Toughness
Requirements for Protection Against Pressurized Thermal Shock.'' In
addition, the large diameter pipe welds attached to, or next to, the
reactor vessel do not receive sufficient radiation to cause
embrittlement. Finally, Type 316 stainless steel weld material, in
which the microfissures were discovered, is resistant to corrosion in a
PWR coolant environment, and the vibratory loads are insufficient to be
a concern for large diameter piping.
In a letter to the Petitioner dated May 13, 1996, the staff stated
that in order to determine if there is any long-term safety
significance of the microfissures, the staff will review the inservice
inspection results for the welds identified as being susceptible to
microfissures. The staff has now completed its review of the inservice
inspection tests results for welds susceptible to microfissures. The
staff's review confirmed that no unacceptable indications have been
observed during inservice inspection. In addition, pressure tests have
not identified any leakage. These tests indicate that 23 years of plant
operation have not caused the microfissures to grow to a size
detectable by inservice inspection or through-wall leakage. Plug sample
testing was performed by Battelle, Columbus Laboratories, on the
primary coolant system low-ferrite welds (Reference: Battelle's report
dated September 17, 1971, which was transmitted by the licensee to the
NRC by letter dated September 21, 1971). As part of the inservice
inspection program in accordance with 10 CFR 50.55a(g), the licensee
has been performing and continues to perform ASME Code inspections of
large piping welds that may have been susceptible to microfissures at
the time of construction. Additional plug sample testing would not
yield any pertinent additional information and is not needed.
On the basis of the above analyses, inservice inspection, and
pressure test results, microfissures are not considered a long-term
safety-significant issue for Maine Yankee. Accordingly, the
Petitioner's remaining requests for NRC action based on asserted
microfissures in large piping welds is denied.
III. Conclusion
As explained above, and as requested by the Petitioner, the staff
examined the adequacy of containment design and susceptibility of welds
to microfissures. For the reasons stated above, no basis exists for
taking any further action in response to the Petition. Accordingly, no
action pursuant to 10 CFR 2.206 is being taken in this matter.
A copy of this Director's Decision will be filed with the Secretary
of the Commission for Commission review in accordance with 10 CFR
2.206(c) of the Commission's regulations. As provided by this
regulation, this Director's 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 20th day of November 1996.
For the Nuclear Regulatory Commission.
Frank J. Miraglia,
Acting Director, Office of Nuclear Reactor Regulation.
[FR Doc. 96-30155 Filed 11-25-96; 8:45 am]
BILLING CODE 7590-01-P
