ML17187A401
| ML17187A401 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities  |
| Issue date: | 04/04/1996 |
| From: | Ring M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML17187A400 | List: |
| References | |
| 50-237-96-05, 50-237-96-5, 50-249-96-05, 50-249-96-5, 50-254-96-05, 50-254-96-5, 50-265-96-05, 50-265-96-5, NUDOCS 9604160329 | |
| Download: ML17187A401 (8) | |
See also: IR 05000237/1996005
Text
U.S. NUCLEAR REGULATORY COMMISSION
REGION III
/
REPORT NOS. 50-237/96005CDRS); 50-249/96005(0~
50-254196005(DRSl: 50-265/96005(DRS)
FACILITY
Dresden Nuclear Station, Units 2 and 3
Quad Cities Nuclear Station, Units l and 2
License Nos. DPR-19; DPR-25; DPR-29; DPR-30
LICENSEE
Commonwealth Edison Company
Opus West II I
1400 Opus Place - Suite 300
Downers Grove, IL 60515
DATES
February 14 through April 1, 1996
INSPECTORS
D. Hi)ls, Lead Engineer
G. Hausman, Lead Engineer
R. Landsman, Project Engineer
J. Gavula, Reactor Inspector
J. Guzman, Reactor Inspector
A. Dunlop, Reactor Inspector
APPROVED BY
M. A. Ring, Chief
Lead Engineers Branch
ARE/\\S INSPECTED
A routine, unannounced inspection of engineering was performed using
Inspection Procedures 37551 and 92903.
Specifically, an expanded inspection
was conducted following NRC concerns with resolution of nonconforming
conditions during the preceding inspection period.
9604160329 960411
ADOCK 05000237
G
EXECUTIVE SUMMARY
Dresden and Quad Cities Nuclear Power Stations
Report No. 96005
ENGINEERING
The inspectors identified two apparent violations involving untimely
corrective actions and reporting deficiencies for design and licensing basis
nonconforming conditions. Specific examples concerned a failure to meet the
low pressure coolant injection (LPCI) corner rooms' structural steel design
margins for Dresden and Quad Cities and a reactor protection system (RPS)
single failure vulnerability for Dresden. A third apparent violation
identified by the licensee involved previous design control weaknesses which
resulted in these nonconforming conditions.
The apparent corrective action and reporting violations reflected an
inadequate licensee safety focus regarding prompt analysis and correction of
facility design deficiencies that conflicted with the facility licensing
basis. This inadequate safety focus caused the licensee to consider these
issues to be of low safety significance, adversely affecting the thoroughness
of the technfcal approach and licensee management decisions.
The results of a broader inspection of the licensee's approach to licensing
and design basis issues at Dresden, including additional observations *
supporting the above conclusions, will be discussed in Inspection Report
50-010/237/249/96004.
.
Summary of Open Items
Violations: Three apparent.violations identified (Section 3.0)
Non-cited Violations:
None
Unresolved Items:
One identified (Section 2.1.3)
Inspector Followup Items:
None
2
Inspection Details
1.0
Inspection Objectives
An unresolved item (50-237/249/95015-05) identified at Dresden by an NRC
inspector involved untimely resolution to a nonconforming condition.
Specifically, LPCI corner rooms' structural steel design margins were
not met.
This inspection focused on a more detailed technical review of
that issue at Dresden and Quad Cities, as well as expanded reviews to
evaluate licensee safety focus on resolution of other identified
licensing and design basis discrepancies.
Broader related issues involving the licensee's emphasis on resolving
operability evaluations, licensing and design basis nonconforming
conditions, and Updated Final Safety Analysis Report (UFSAR) deviations
at Dresden will be discussed in Inspection Report 50-010/237/249/95004.
2.0
Untimely Resolution of Licensing and Design Basis Nonconforming
Conditions Addressed in Open Operability Evaluations (OEs)
2.1
LPCI Corner Room Structural Steel Failure To Meet Applicable Design
Margins
2.1.1 Dresden History Surrounding Issue
In 1991, the licensee's architect engineer (AE) identified undocumented
load changes on the LPCI corner rooms'* structural support steel for the
LPCI heat exchangers and LPCI and core ._sp-r:ay piping at Dresden.
The
licensee indicated that undocumented changes in structural steel
attached loads resulted from failures to account for load changes during
previous pipe support modifications.
The licensee's AE performed
walkdowns in 1993, and identified to.the licensee in January 1994, that
the corner room structural steel did not meet the allowable design
margins stated in UFSAR Section 3.8.4.1.4 and Table 3.8-11 for
Category 1 structural steel. This affected all four corner rooms (two
for each unit).
The licensee's AE also indicated, based on previous experience with
similar conditions, that wore refined and extensive calculations would
likely show the structural steel to be within the UFSAR allowables.
These calculations were never performed. A qualitative operability
assessment conducted for both units on January 6, 1994, concluded that
the structural steel was operable based on the steel condition noted
during the walkdowns and assumed conservatisms in the methods used to
calculate piping loads on structural steel. Although the structural
steel condition was calculated to be outside the design basis of the
plant, the licensee did not submit a licensee event report (LER) to the
NRC.
Originally in 1994, the licensee planned to address this structural
steel concern in a timely manner; however, licensee management postponed
actions in mid-1994 to redirect resources to the core shroud cracking
issue and other emergent activities.
On September 20, 1995, engineering
personnel raised the corner room structural steel issue to the
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licensee's Business Review Committee (BRC), recommending modifications
to the plant. The BRC consisted of senior plant management who
allocated resources and funding to plant activities. Modifications to
the structural steel were recommended in lieu of more refined
calculations due to lower cost and increased flexibility for future
piping support changes.
On October 20, 1995, the BRC approved
engineering design work to begin in the last quarter of 1995 with
modification installation during 1996.
The October 1995 BRC presentation package informed senior plant
management of NRC expectations with regard to timeliness of resolving
this issue.
The package stated that Dresden was operating outside of
NRC's expectations for timely resolution of design discrepancies as
described in NRC Generic Letter 91-18, "Information To Licensees
Regarding Two NRC Inspection Manual Sections on Resolution of Degraded
and Nonconforming Conditions On Operability," and the NRC's Safety
Evaluation Report (SE) dated September 27, 1991, regarding Dresden and
Quad Cities piping system operability criteria.
When the inspector raised this issue in February 1996, engineering
design work had not yet begun due to the extended Unit 2 refuel outage
and the engineers did not expect installation to be c9mplete until 1997,
if the modifications could be done during facility operation.
In a
subsequent letter to the NRC dated March 4, 1996, the licensee described
revised plans to perform some modifications during the current Unit 2
refuel outage (D2R14). However, complete modifications to restore UFSAR
stress margins were not planned until the following refuel outage
(D2R15), three years after problem identification. Subsequently, the
licensee decided to perform modificatio~s.to restore full UFSAR margins
during D2Rl4 for Unit 2 and the next refuel outage (D3Rl4) for Unit 3.
2.1.2 Quad Cities History Surrounding Issue
Quad Cities' history regarding this matter was similar to Dresden's.
In
December 1991, the licensee's AE identified several corner room beams
that did not meet UFSAR design allowables.
In 1992, two design change
notices were prepared to reinforce two of the deficient beams identified
in 1991.
No additional actions were taken. After the issue was raised
again at Dresden in 1995, a quantitative operability evaluation for Quad
Cities was completed on August 25, 1995.
Quad Cities personnel did not
submit an LER on this issue to the NRC.
Quad Cities personnel had not planned to perform modifications to
address the nonconforming condition during the current Unit 1 refuel
outage.
In March 1996, Quad Cities management decided to perform Unit 1
modifications prior to startup. Unit 2 modifications are planned for
its next refuel outage.
2.1.3 Dresden Unit 3 and Quad Cities Unit 2 Operability Concerns
At the end of the inspection period, NRC specialist inspectors were
reviewing licensee operability evaluations regarding the corner rooms'
structural steel for Dresden Unit 3 and Quad Cities Unit 2.
Operability
for these units is considered an unresolved item (50-249/265/96005-01)
pending completion of this NRC review.
4
2.2
Reactor Protection System CRPSl Single Failure Vulnerability
(Applicable to Dresden Only)
2.2.1 History Surrounding Issue at Dresden
A General Electric 10 CFR Part 21 report dated December 3, 1993,
informed the licensee of an inadequate separation problem in the RPS at
Dresden. A 1975 modification added scram pilot solenoid valve
indicating lights to* the back panels in the control room.
Corresponding
current limiting isolation resistors for all four scram solenoid groups
had been mounted next to each other on a single "breadboard" for each
RPS division. This configuration resulted in the possibility of a hot
short simultaneously across all four solenoid groups causing th: scram
solenoids to remain energized for multiple or all control rod groups. A
December 23, 1993, licensee operability evaluation concluded both units
remained operable due to adequate backup systems and operator actions.
Although this single failure vulnerability was outside the design basis
of the plant, the licensee did not submit an LER to the NRC.
A planned modification to resolve this issue involved minimal rewiring
in control room panels to house the indicating light resistors in
existing separate scram contractor boxes.
This modification, although
relatively simple and approved management for implementation, was not
scheduled to be completed during the current Unit 2 refuel outage. .
~odifications were scheduled for the next refuel outages on both units
(D3Rl4 and D2Rl5).
Subsequent to the inspectors' discussions, the
licensee decided to perform modifications in the current Unit 2 outage
and the next Unit 3 refuel outage.
2.2.2 Design Basis
This vulnerability to a postulated single failure was contrary to the
design specification. General Electric Design Specification 22A2501,
"Separation Requirements For Reactor Safety and Engineered Safeguards
Systems," dated January 28, 1969, stated that:
Single failure criteria were defined in accordance with
Paragraph 4.2 of IEEE 279, "Proposed IEEE Criteria for Nuclear
Power Plants Protection Systems," Revision 10, dated March 4,
1968.
Design basis events included gross failure of electrical equipment
in any single compartment of instrument or control panels that
could result from a short circuit.
No single design basis event was permitted to disable an essential
automatic protective function such as RPS.
Deviation from the design specification also constituted a condition
contrary to the licensing basis described in the UFSAR.
Standard
IEEE-279-1968, Revision 10, stated that a specific protection system
design basis shall be provided that documents the range of conditions
throughout which the system must perform. This document also stated
that any single failure within the protection system shall not prevent
proper protection system action when required, including shorting or
5
open circuiting of interconnecting signal or power cables and single
credible malfunctions or events that cause a number of consequential
component failures.
UFSAR Section 7.2 indicates through various
statements that circuit isolation and single failure criteria in
IEEE-279-1968 were met.
3.0
Apparent Violations
Inadequate design controls which allowed conditions contrary to the
design and licensing basis for both the corner room steel design margins
and RPS single failure vulnerability are examples of an apparent
violation of 10 CFR Part 50, Appendix B, Criterion III
(50-237/249j254/265/96005-02a and 50-237/249/96005-02b).
Failure to take prompt corrective actions for the corner rooms'
structural steel design margins and RPS single failure vulnerability
. nonconforming conditions is an apparent violation of 10 CFR Part 50,
Appendix B, Criterion XVI (50-237/249/254/265/96005-03a and
50-237/249/96005-03b).
Undocumented and unanalyzed structural steel load changes were known to
exist since 1991 and the structural steel design margins were known to
be exceeded since at least January 1994.
Existing plans would not have
resolved these nonconforming conditions until approximately six years
after initial identification.
The failure to meet RPS design specifications was known since December
1993.
Existing plans would not have resolved that nonconforming
condition until four years after disCO'v'._er;:.
Ample opportunity had existed to resolve these problems.
Refuel outages
had been conducted on Dresden Unit 3 during the Summer 1994 and on
Dresden Unit 2 from June 1995 through March 1996 (current). Several
forced outages had also occurred during those time periods.
Failures to submit LERs for both the corner rooms' structural steel
design margins and RPS single failure vulnerability nonconforming
conditions are examples of an apparent violation of 10 CFR Part
50.73(a)(2)(ii) (50-237/249/254/265/96005-04a and 50-237/249/96005-04b).
4.0
Safety Significance of Apparent Violations
The structural steel issue represented a common vulnerability to all the
low pressure emergency core cooling systems on both units in the event
of an earthquake.
Licensee calculations indicated operating basis
earthquake (QBE) criteria were significantly exceeded.
The RPS single failure vulnerability, could have prevented the scram
solenoids for multiple control rod groups from de-energizing preventing
shutdown of the reactor.
Backup methods including the alternate rod
insertion system and manual operator actions remained available to shut
down the reactor.
The failures to submit LERs were missed opportunities to provide greater
visibility and earlier resolution of these issues.
6
5.0
Inadequate Licensee Emphasis On Licensing and Design Basis
The apparent corrective action and reporting violations reflected an
inadequate licensee safety focus regarding prompt analysis and
correction at facility design deficiencies that conflicted with the
facility licensing basis. This inadequate safety focus caused the
licensee to regard these issues to be of low safety significance,
adversely affecting the thoroughness of the technical approach and
licensee management decisions.
Inspector interviews of licensee staff
identified several considerations which may have governed licensee
decisions:
The licensee's AE contended that more extensive calculations alone
would show adequate margin for the structural steel. However, the
licensee failed to perform such calculations to verify this
conclusion.
The inspector reviewed other cases involving
nonconforming structural steel and piping supports that had been
reported and corrected in a timely manner.
In those cases,
however, the AE had not taken any written position with respect to
the adequacy of design margins.
Licensee staff believed there was a low probability of occurrence
of events or conditions for which these particular nonconforming
conditions would become important.
- These were older issues, first identified prior to the current
senior management being assigned to Dresden and Quad Cities.
In both cases, the fact these issues were nonconforming conditions with
respect to the licensing and design basis and possible margin reductions
increasing the probability of structural failure did not cause
sufficient concern to result in timely action.
The licensee did not
plan to perform 10 CFR 50.59 safety evaluations to determine whether
these nonconforming conditions were unreviewed safety questions or to
perform modifications prior to startup from refuel outages.
6.0
Persons Contacted and Management Meetings
The inspectors contacted various licensee personnel throughout the
inspection period. Senior personnel are listed below.
6.1
Public Technical Meeting
A public meeting was conducted on March 5, 1996, in the NRC Region III
Office, to discuss licensee calculations involving the LPCI corner room
structural steel issue at both Dresden and Quad Cities.
6.2
Exit Meeting
After the conclusion of the inspection period, the inspectors met with
licensee representatives at Dresden (denoted by*) on March 29, 1996,
and by telephone with Quad Cities licensee representatives (denoted by
+) on April 1, 1996, and summarized the scope and findings of the
inspection activities. The licensee did not identify any of the
documents or processes reviewed by the inspectors as proprietary.
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II
S. Perry, Acting Site Vice President, Dresden
- J. Heffley, Units 2 and 3 Station Manager, Dresden
- R. Kundalkar, Site Engineering Manager, Dresden
- F. Spangenberg, Regulatory Assurance Manager, Dresden
- R. Freeman, Plant Engineering Superintendent, Dresden
- E. Connell, Design Engineering Superintendent, Dresden
+B. Pearce, Station Manager, Quad Cities
+S. Eldridge, Design_Engineering Supervisor, Quad Cities
+N. Chrissotimos, Regulatory Assurance Supervisor, Quad Cities
+B. Ryback, Licensing, Quad Cities
+I. Johnson, Licensing, Quad Cities
- .
8