ML20046D411
| ML20046D411 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 08/16/1993 |
| From: | Hodges M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Opeka J CONNECTICUT YANKEE ATOMIC POWER CO. |
| Shared Package | |
| ML20046D412 | List: |
| References | |
| NUDOCS 9308190253 | |
| Download: ML20046D411 (4) | |
See also: IR 05000213/1993080
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AUG 161993
Docket No. 50-213
Mr. John F. Opeka
Executive Vice President - Nuclear
Connecticut Yankee Atomic Power Company
P. O. Box 270
Hartford, Connecticut 06141-0270
Dear Mr. Opeka:
SUBJECT:
NRC AUGMENTED INSPECTION TEAM (AIT) REGARDING TWO LOSS
OF OFFSITE POWER EVENTO AND THE LOSS OF MOTOR-CONTROL-
CENTER-5 NRC REPORT NO. 50-213/93-80
The encloseli rerort n fers to the NRC Augmented Inspection Team (AIT), led by
Mr. Jame; Tra p of t' tis office, on June 30 through July 9,1993, at the Haddam Neck Plant
in Hadda, CannectMut. The purpose of this inspectioa was to review the circumstances
regarding two ap& rate loss of offsite power events, and a loss of motor-control-center-5
(MCC-5) that occurred during the conduct of test activities At the conclusion of the
inspection, the team findings were discussed with Mr. Stetz and members of your staff at an
exit meeting that was open for public observation on July 27,1993.
The scope of the inspection included developing a detailed event description, evaluating the
root causes for the events, assessing the effectiveness of corrective actions, and evaluating
the safety significance of each event. The inspection consisted of selective examination of
procedures and representative records, observations of testing and inspections, and inten'iews
with personnel.
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The less of offsite power events were significant because they caused a temporary loss of
shutdown cooling and the loss of offsite power is a precursor to station blackout. The
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reliable operation of MCC-5 is vital to plant safety because both trains of emergency core
cooling system injection valves are powered from this motor-control-center. Based on the
significance of these events, all of which occurred in a short time period, the NRC
dispatched an AIT.
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Mr. John F. Opeka
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The root causes for the June 22 and June 26,1993, loss of offsite power events were
positisely identified as a wiring error and a blown fuse, respectively. For both events, the
operator actions to mitigate the consequences of the events were appropriate. The corrective
actions taken in response to these events were reviewed by the AIT and determined to be
acceptable. The NRC team concluded that these events were the result of defcctive
nonsafety-related equipment and were not the result of recent performance deficiencies by
plant staff or procedures.
The root cause for the June 27,1993, failure of the MCC-5 automatic bus transfer scheme
was not positively identified. Although the root cause was not identified, two highly suspect
components were identified and replaced. Your corrective actions and compensatory
measures taken to ensure the reliability of MCC-5 were outlined in your letter to the NRC,
dated July 15,1993, " Commitments to Test Motor-Control-Center-5." We have reviewed
these commitment, and determined that the proposed actions and compensatory measures are
appropriate. While trouble-shooting the automatic bus transfer (ABT) failure, your staff
identified a potential generic problem with the Westinghouse DB 25 breaker, 52X relays. At
the conclusion of this inspection, this potentially generic breaker failure concern was still
under review by your staff and the breaker vendor. We expect that this issue will be
resolved and appropriate actions will be taken in an expeditious manner. In addition, your
letter states that you plan to conduct a review of potential design changes to the ABT which
could improve the reliability of this scheme. We request that you provide the results of this
design review and the schedule for implementing any design changes identified to the
Region I Regional Administrator.
The NRC team also noted two issues regarding the licensing basis of MCC-5. The updated
UFSAR, Section 8.3, states, in part, that "The Class 1E system has he redundancy,
capacity, capability, and reliability to supply power to all safety-related loads. This system
ensures a safe plant shutdown to mitigate accident effects, even in the event of a single
failure." This statement does not appear to be accurate as related to single failures and
MCC-5. In addition, the team questioned the applicability of 10 CFR 50.46(d), which
explicitly states that the performance of the emergency core cooling syste
(ECCS) system
must include in particular Criterion 35 of Appendix A, which requires that le ECCS safc:y
function be accomplished assuming a single failure. The current design of the ECCS system
does not satisfy the requirement of Criterion 35 due to the single failure vulnerabilities of
MCC-5. While the team noted that an exemption had been granted by the NRC for the
MCC-5 single failure vulnerability during original plant licensing, an explicit exemption from
the 50.46 requirement was not apparent to the team. Both of these issues are currently being
reviewed by the NRC.
In accordance with 10 CFR 2.790 of the Commission's regulations, a copy of this lettcr and
the enclosed inspection report will be placed in the NRC Public Document Room.
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$r. John F. Opeka
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We will gladly discuss any questions you have conceming this inspection.
Sincerely,
Y Gyl D,
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Marvin W. Hodges, Dir-ctor
Division of Reactor Safety
Enclosure: NRC Region I Inspection Report No. 50-213/93-80
cc w/ encl:
W. D. Romberg, Vice President, Nuclear, Operations Services
J. P. Stetz, Vice President, Haddam Neck Station
G. H. Bouchard, Director, Nuclear Quality Services
D. J. Ray, Unit Director
R. M. Kacich, Director, Nuclear Licensing
Gerald Garfield, Esquire
Nicholas Reynolds, Esquire
K. Abraham, PAO (2)
Public Document Room (PDR)
local Public Document Room (LPDR)
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Nuclear Safety Information Center (NSIC)
NRC Resident inspector
State of Connecticut SLO
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Mr. John F. Opeka
bec w/ encl:
Region 1 Docket Room . with concurrences)
(
bec w/enci (VIA E-51 AIL):
J. Stolz, NRR/PD I-4
V. McCree, OEDO
bec w/o enci (VIA E-31 AIL):
M. Hodges, DRS
J. Durr, DRS
J. Trapp, DRS
bec w/ encl: AIT Reports Only
The Chairman
Commissioner Rogers
Commissioner Remick
Commissioner DePlanque
J. Taylor, EDO
T. Murley, NRR
Paul Boehnert, Chairman, ACRS
Ken Raglin. Director, TCC
DCD (OWFN Pl-37) (Dist. Code #1E10)
A. Chaffee. NRR/ DORS /EAB
E. Jordan, AEOD
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