ML20044F923
| ML20044F923 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/24/1993 |
| From: | Milhoan J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Yelverton J ENTERGY OPERATIONS, INC. |
| References | |
| EA-93-108, NUDOCS 9306010202 | |
| Download: ML20044F923 (5) | |
See also: IR 05000313/1991002
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REGION IV
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611 RYAN PLAZA DRIVE. SUITE 400
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AR LINGT ON, T E X AS 760R8064
MAY 24 1993
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Dockets:
50-313
50-368
Licenses:
NpF-6
EA 93-108
Entergy Operations, Inc.
ATTN:
J. W. Yelverton, Vice President
Operations, Arkansas Nuclear One
Route 3, Box 137G
Russellville, Arkansas 72801
SUBJECT:
ENFORCEMENT DISCRETION (NRC INSPECTION REPORT NO. 91-02)
This refers to the NRC's inspection of the electrical distribution systems at
the Arkansas Nuclear One (AND) facility September 10 through October 18, 1991.
The inspection report, which was issued on November 21, 1991, described a
concern about the capability of the 161-kilovolt (kV) transmission system to
provide an independent off-site source of electrical power to the facility, as
required by 10 CFR Part 50, Appendix A, Criterion 17. This issue, which was
identified by Entergy Operations, Inc., and discussed with the NRC during the
inspection, was left as an unresolved item pending conclusion of the NRC's
review. As you know, the NRC has conducted an extensive review of this matter
to determine whether compliance with General Design Criterion 17 had been met
at ANO prior to the discovery of this condition and your implementation of
corrective actions.
The NRC appreciates Entergy Operations' cooperation and
assistance in responding to several requests for information to support this
review.
General Design Criterion 17 requires, in part, that power from the
transmission network to the on-site electrical distribution system be supplied
by two physically independent circuits, and that each of the off-site power
circuits be designed to be available in sufficient time following a loss of
all on-site power suWies and the loss of the remaining off-site power
circuit to effect a safe shutdown of both units.
The two required sources of
off-site power are supplied to the ANO site through the 500kV switchyard 'and
the 161kV switchyard.
The 500kV switchyard normally supplies power through an
on-site autotransformer to the 161kV switchyard.
On October 5,1991
Entergy Operations infor* the * of an engineering
evaluation, which had been initiated to follow up a concern raised some days
earlier.
The evaluation had determined that the minimum design voltage at the
161kV switchyard could not be assured under all operating conditions,
particularly during expected summer peak loading, if the 500kV system were not
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available.
The potential for degradation of the available voltage occurred as
the result of increased off-site loading of the 161kV transmission system.
That potential had not been detected earlier, in part, because the 500kV
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transmission system had maintained the 161kV transmission system at acceptable
voltage levels and, in part, because Entergy Operations had not instituted
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formal procedures requiring periodic review of the transmission network to
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assure that the off-site voltage levels required by ANO were being maintained.
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When the deficient condition was identified, immediate procedural changes were
implemented to assure that two acceptable sources of off-site electrical power
would be available as required by General Design Criterion 17.
In addition,
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modifications to the 161kV transmission system were completed prior to the
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summer of 1992, when peak loading conditions were expected.
To assure that
transmission system load growth does not again result in inadequate off-site
voltage levels, Entergy Operations now requires that off-site voltage levels
be re-evaluated every 2 years.
The NRC is satisfied that the procedural
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changes and the modifications provide assurance that adequate voltage levels
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will be available under all operating conditions.
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The NRC has determined that General Design Criterion 17 was not met at ANO
between 1980 and 1991, because there was no assurance that the 161kV off-site
power circuit could have supplied sufficient voltage for the full auxiliary
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loads (shutdown loads) of both units using the assumptions in the general
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design criteria. As a result of this condition, ANO also failed to comply
with General Design Criterion 5, which states, in part, .that systems important
to safety shall not be shared among nuclear power units unless it can be shown
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that such sharing will not significantly impair their ability to perform their -
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safety functions, including, in the event of an accident in one unit, an
orderly shutdown and cooldown of the remaining units.
Entergy Operations, Inc.'s failure to ensure compliance with these
requirements created a potential, during peak loading conditions, that
insufficient electrical power would have been available to maintain ANO
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Units 1 and 2 in a safe shutdown condition.
Although the probability of the
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loss of the 500kV system during peak conditions concurrent with a loss of all
on-site power is low, the NRC considers this a significant regulatory concern.
Therefore, the violations of the general design criteria are classified in the
aggregate as a Severity Level III problem.
In accordance with the " General
Statement of Policy and Procedure for NRC Enforcement Actions," (Enforcement
Policy) 10 CFR Part 2, Appendix C, a penalty is considered for a Severity
Level 111 problem.
However, in accordance with Section VII.B.4 of the
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Enforcement Policy, I have been authorized not to propose a civil penalty
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because:
1) this condition was discovered by Entergy Operations as the result
of various engineering evaluations in preparation for the electrical
distribution system functional inspection;
2) the uniqueness-of the local
distribution system had masked the problem, making it highly unlikely that
Entergy Operations would have identified this condition through its routine
surveillance and quality assurance programs; and (3) when the problem.was
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identified, immediate corrective actions were implemented and physical
modifications to the transmission system were completed prior to the next peak
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loading period.
In addition, because the existence of this conditinn is not
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Entergy Operations, Inc.
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indicative of present performance at ANO and there was no prior notice of a
potential problem, a Notice of Violation will not be issued in this case.
No response to this letter is required.
In accordance with 10 CFR 2.790 of
the NRC's " Rules of Practice," a copy of this letter will be placed in the NRC
Public Document Room.
Sincerely,
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Mi hoan
E egional Administrator
CC:
Entergy Operations, Inc.
4
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ATTN:
Donald C. Hintz, President &
Chief Operating Officer
P.O. Box 31995
Jackson, Mississippi
39286
Entergy Operations, Inc.
,
ATTN: John R. McGaha, Vice President
Operations Support
P.O. Box 31995
Jackson, Mississippi
39286
Wise, Carter, Child & Caraway
ATlN:
Robert B. McGehee, Esq.
P.O. Box 651
Jackson, Mississippi
39205
Entergy Operations, Inc.
ATTN:
James J. Fisicaro
Director, Licensing
Route 3, Box 137G
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Russellville, Arkansas 72801
Entergy Operations. Inc.
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ATTN:
Michael B. Sellman, General
Manager, Plant Operations
Route 3, Box 137G
Russellville, Arkansas 72801
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Honorable Joe W. Phillips
County Judge of Pope County
Pope County Courthouse
Russellville, Arkansas 72801
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. ,Entergy Operations, Inc.
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.Winston & Strawn
ATTN: Nicholas S. Reynolds, Esq.
- 1400 L-Street, N.W.
Washington, D.C.
20005-3502
ATTN: Ms. Greta Dicus, Director
Division of Radiation Control and
Emergency Management
4815 West Markham Street
Little Rock, Arkansas 72201-3867
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B&W Nuclear Technologies
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ATTN:
Robert B. Borsum
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Licensing Representative
1700 Rockville Pike, Suite 525
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Rockville, Maryland 20852
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Admiral Kinnaird R. McKee, USN (Ret)
214 South Morris Street
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Oxford, Maryland 21654
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ABB Combustion Engineering
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Nuclear Power
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ATTN: Charles B.. Brinkman
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Manager, Washington
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Nuclear Operations
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12300 Twinbrook Parkway, Suite 330
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Rockville, Maryland 20852
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