Referencing 6/29/79 Letter Re Multiple Equipment Failures (Generic Letter 79-44)
GL79044
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C. 20555
September 21, 1979
ALL PRESSURIZED WATER REACTORS
Gentlemen:
The enclosed letter dated June 26, 1979 regarding multiple equipment
failures and surveillance testing errors was sent to all pressurized water
reactors. However, due to distribution problems, the letters were delayed
and apparently not all licensees have received their copy.
To ensure that all licensees are in receipt of the June 26, 1979 letter, a
copy is being transmitted with this letter, in addition to a copy of the
July 16, 1979 Office of Inspection and Enforcement inspection report
pertaining to the events referred to in the letter.
Within 30 days of receipt of this letter, you are requested to provide the
results of the reviews discussed in the June 26, 1979 letter.
Sincerely,
Darrell G. Eisenhut, Acting Director
Division of Operating Reactors
Office of Nuclear Reactor Regulation
Enclosures:
As Stated
7910230561
.
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C. 20555
June 26, 1979
ALL PRESSURIZED WATER REACTORS
Gentlemen:
Recently, because of operator error, an inadvertent reactor scram and safety
injection occurred during monthly surveillance tests of the safeguards
system at a PWR facility.
At the time of the event, train "A" of the safeguards system had been placed
in "test", and the operator, in addition to inserting a high steam flow
signal required by the test, inadvertently incorrectly inserted a low steam
pressure signal. This action resulted in a low steam pressure signal
(signifying a main steam line break) in train "A" which initiated main steam
isolation valve (MSIV) isolation and a reactor scram. One MSIV, however, did
not close because of a valve solenoid failure. The resultant differential
pressure between two steam lines initiated a safety injection signal from
train "B". In the ensuing events several more equipment failures occurred.
One feedwater regulation valve failed to close because of another solenoid
failure. The steam driven auxiliary feedwater pump tripped on overspeed and
one of the steam generator atmospheric relief valves failed to fully reseat
upon closure.
This occurrence, with its ensuing sequence of events, is of concern to the
NRC staff because of the serious questions that are raised due to the
multiple equipment failures and whether a very real problem could exist that
has not been analyzed. For example, the potential for common mode failures
(in this case two apparently independent solenoid valve failures) should be
investigated to ensure that a problem does not exist which could negate the
criteria assumed in your previous accident analyses or which could lead to
an overall reduction in system reliability.
This occurrence is also of concern because of an apparent sense of
complacency towards periodic surveillance requirements in general and on
engineered safeguards systems in particular which has all too often resulted
in inadvertent reactor scrams and safety injection system actuations. From
the standpoint of unnecessary challenges to the reactor trip and the
safeguards systems and the imposition of unnecessary thermal stress cycles
on reactor coolant system and its components, this is undesirable.
.
- 2 - June 26, 1979
You and your plant supervisors should review the events described in this
letter, to determine whether similar errors have occurred or could occur at
your facility and whether the potential exists for a problem associated with
occurrences that you have not previously considered.
In addition, it is requested that management policies and procedures be
reviewed and strengthened as necessary to assure that multiple equipment
failures in safety-related systems will be vigorously pursued and analyzed
to identify potential failure modes not previously considered that could
lead to a significant reduction in the ability of safety systems to function
as required. Finally, you are requested to review your engineered safety
system surveillance procedures to determine whether appropriate cautions are
included and to ensure that plant operators and supervisors are aware of the
importance of avoiding challenges to the protective features of your
facility.
Within 30 days of receipt of this letter, please submit, in accordance with
10 CFR SS 50.54(f) of the Commission's regulations, the results of these
reviews. In addition to licensing reviews of these matters, we have
requested that the NRC's Office of Inspection and Enforcement perform a
followup inspection on these matters in the near future.
Sincerely,
Darrell G. Eisenhut, Acting Director
Division of Operating Reactors
Office of Nuclear Reactor Regulation
.
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION III
799 ROOSEVELT ROAD
GLEN ELLYN, ILLINOIS 60137
JUL 16 1979
Docket No. 50-295
Docket No. 50-304
Commonwealth Edison Company
ATTN: Mr. Byron Lee, Jr.
Vice President
Post Office Box 767
Chicago, IL 60690
Gentlemen:
This refers to the inspection conducted by Mr. J. E. Kohler of this office
on April 28 through June 1, 1979, of activities at Zion Nuclear Power
Station, Units 1 and 2, authorized by NRC Operating License No. DPR-39 and
No. DPR-48 and to the discussion of our findings with Mr. N. E. Wandke at
the conclusion of the inspection.
The enclosed copy of our inspection report identifies areas, examined during
the inspection. Within these areas, the inspection consisted of a selective
examination of procedures and representative records, observations, and
interviews with personnel.
No items of noncompliance with NRC requirements were identified during the
course of this inspection.
In accordance with Section 2.790 of the NRC's "Rules of Practice," Part 2,
Title 10, Code of Federal Regulations, a copy of this letter and the
enclosed inspection report will be placed in the NRC's Public Document Room,
except as follows. If this report contains information that you or your
contractors believe to be proprietary, you must apply in writing to this
office, within twenty days of your receipt of this letter, to withhold such
information from public disclosure. The application must include a full
statement of the reasons for which the information is considered
proprietary, and should be prepared so that proprietary information
identified in the application is contained in an enclosure to the
application,
.
Commonwealth Edison Company - 2 -
We will gladly discuss any questions you have concerning this inspection.
Sincerely,
R. F. Heishman, Chief
Reactor Operations and
Nuclear Support Branch
Enclosure: IE Inspection
Reports No. 50-295/79-13
and No. 50-304/79-12
.
U.S. NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
REGION III
Report No. 50-297,/79-13; 50-304/79-12
Docket No. 50-295; 50-304 License No. DPR-39; DPR-48
Licensee: Commonwealth Edison Company
Post Office Box 767
Chicago, IL 60690
Facility Name: Zion Nuclear Power Station, Units 1 and 2
Inspection At: Zion Site, Zion, IL
Inspection Conducted: April 28 through June 1, 1979
Inspector: J. E. Kohler 7/13/79
Approved By: F. L. Spessard, Chief 7/13/79
Reactor Projects Section 1
Inspection Summary
Inspection on April 28 through June 1, 1979, (Report No. 50-295/79-13;
50-304/79-12)
Areas Inspected: Routine inspection of plant operations, maintenance,
non-routine events occurring during the inspection, quality assurance audit
results, plant cleanliness, and spent fuel pool modification activities. The
inspection involved 144 hours of onsite inspection by one NRC inspector.
Results: No items of noncompliance were identified.
.
DETAILS
1. Persons Contacted
N. Wandke, Plant Superintendent
*C. Schumann, Operating Assistant Superintendent
*T. Parker, Assistant Technical Staff Supervisor
*B. Ward, Unit 2 Operating Engineer
E. Fuerst, Unit 1 Operating Engineer
*B. Harl, Quality Assurance
J. Joosten, Primary Group Leader Tech Staff
K. Schultz, Training Supervisor
F. Resick, Station Health Physicist
R. Landrum, Nuclear Station Operator
T. Flowers, Shift Engineer
N. Valos, Shift Foreman
F. Pauli, Shift Engineer
L. Pruett, Shift Foreman
D. Ray, B Operator
J. Johnson, B Operator
T. White, Instrument Mechanic
D. Kaley, Nuclear Station Operator
E. Murach, Maintenance Assistant Superintendent
L. Soth, Administration and Support Assistant Superintendent
G. Armstrong, Shift Engineer
N. Loucas, Shift Foreman
D. Walden, Fuel Handling Foreman
J. Lafontaine, Fuel Handling Foreman
P. Kuhner, Quality Control
*Denotes those present at the exit interview.
2. Safety Injection Unit 23 1979 (LER 50-295/79-42)
At approximately 1:45 on May 23, 1979 with Unit 1 at 100% power a
safety injection occurred during performance of periodic test procedure
PT 10a and b, the monthly safeguards logic test. The safety injection
resulted in main steam isolation valve closure and full secondary steam
relief. No structural damage or water hammers occurred. The injection
lasted for approximately three minutes during which time the licensee
personnel monitored containment pressure and temperature, primary
system pressure, pressurizer level and steam generator levels. Shift
personnel determined that the safety injection was inadverent not
resulting from a steam line break, and terminated the safety injection.
Confirmation that steam line break indication did not exist on plant
instrumentation was obtained by the NRC resident inspector.
- 2 -
.
The cause of the safety injection was attributed to personnel error and
failure of the B main steam isolation valve to close from safety
injection Train A. The procedure (PT 10a and b) calls for developing
the logic for high steamline flow and requires depressing a pushbutton
labeled RT which is located in the auxiliary electrical area. The RT
pushbutton is depressed while Train A safeguards logic is in test.
While depressing the RT pushbutton, two pages of the procedure were
inadvertently skipped and pushbuttons which yielded a low steamline
pressure were depressed simultaneously with the RT pushbutton. This
action developed a safety injection logic for Train A (high steamline
flow concident with low steamline pressure signifying a steamline
break).
Although Safeguards Train A was in test, valve positioning resulting
from the signals is not inhibited. For steamline break protection, main
steam isolation valves A, B, C and D receive the closure signal from
Train A. The A, C, and D MSIVs closed as designed while the B MSIV
failed to close from Train A. Failure of the B MSIV to close caused a
Train B safeguards actuation from the 100 pound differential pressure
safety injection.
Several discrepancies were noted during and after the safety injection
resulting from Train B. These discrepancies are described in the
following table along with the corrective action and the safety
significance.
Equipment Failure Corrective Action Safety Significance
B MSIV Failed to Pilot valve replaced, Would have closed
(LER close from retested by PT-23 automatically from
No. 79-40) Train A successfully. Train B if real
steamline break
existed. Closed
manually from the
control room.
Feedwater Failed to Solenoid was cleaned, Closed Automatically
Reg. Valve close from repaired and retested from Train B.
1B (DVR Train A by depressing relays
No. 1-79-73) F4, and F5.
Main steam Partially Manually reset Each steamline has
Safety opened and by prying to full five steam safety
Valves failed to open position. valves capable of
reset. passing 110% of rated
steamflow at 110%
steam generator
pressure. No
excessive cooldown
occurred.
- 3 -
.
Equipment Failure Corrective Action Safety Significance
Turbine Started Adjusted governor, The plant has two
Driven but steam performed periodic electric driven and
Auxiliary supply surveillance test one turbine driven
Feedwater valve successfully. auxiliary feedwater
Pump 1A tripped pumps. Only one of
(DVR No. closed. three is necessary
1-79-72) for safe shutdown.
Technical
Specifications
requirement for two
operable pumps was
met.
The inspector considers the mechanical failures associated with this
event to be corrected.
Licensee investigation into this event concentrated on reviewing the
procedure (PT 10 a and b) as well as expected operator actions.
Although two additional licensed operators familiar with PT 10 a and b
were brought in specifically to perform the test, it was determined
that the degree of communication between the two individuals by sound
powered telephone could have been improved. (One individual was in the
control room and one individual was in the auxiliary electrical area).
Furthermore, it was concluded that human engineering deficiencies in
the auxiliary electrical area which require simultaneous depression of
three separate pushbuttons to develop the safeguards signals
contributed to the error.
During the management exit held on June 1, 1979, periodic test
procedure PT 10a and b was discussed as well as possible changes that
were going to be made. These changes dealt with modifications to the RP
pushbutton as well as some procedural modification. At the time of the
management exit, these changes were not finalized. Consequently, this
item will be carried as unresolved pending further resolution by the
licensee and will be followed in subsequent inspections. (295/79-13-01;
304/79-12-01)
No items of noncompliance were identified.
3. QA Audit Performed by Commonwealth Edison
The inspector was made aware of the results of an inhouse quality
assurance audit performed by the corporate off-site audit group. One
significant finding was made regarding implementation of Zion
Administrative Procedure 13-52-8. According to the audit finding all of
the requirements of ZAP13-52-8, which controls the shipment of dry
active wastes, were not being implemented.
- 4 -
.
The inspector discussed this item with the plant's Quality Assurance
Department as well as at the monthly exit. The ZAP in question will be
controlling the anticipated future shipment of old spent fuel racks.
The licensee stated that these problems were being resolved and a
formal response to the in-house audit would be available shortly. At
the time of the management exit, these changes had not been finalized.
Consequently, this item will be considered unresolved pending
resolution by the licensee. (295/79-13-02; 304/79-12-02)
No items of noncompliance were identified.
4. Unit 2 Reduction in Plant Load May 11, 1979
Unit 2 Reduction in Plant Load 79 Unit 2 entered a limiting condition
for operation regarding Technical Specification 4.8.3.c at about 9:00
a.m. on May 11, 1979, when it was found that the 0 diesel generator
would not except load during the time the 2A residual heat removal
(RHR) pump was out of service for maintenance. A 2.5% per minute load
reduction was begun with the anticipated off line time at 1:00 P.M. The
load reduction was cancelled at approximately 12:30 p.m. when the 2A
RHR pump maintenance was completed and the pump was tested and declared
operable. The inspector has no further questions regarding this item.
No items of noncompliance were identified.
5. Special Engineered Safeguards Inspection
As a result of the Three Mile Island incident, the inspector conducted
a special inspection of all engineered safety feature systems at the
Zion Generating Station. The results of this inspection are contained
in a special inspection report which was forwarded to the licensee in
June of 1979. The inspector has no further questions regarding this
item.
6. Plant Cleanliness
The inspector commented during the management exit on 6/1/79 that the
auxiliary building looked clean and that licensee personnel should
continue housekeeping efforts, particularly in any areas where boric
acid might deposit and crystallize.
No items of noncompliance were identified.
7. Technical Specification Comments
During the month, an item pertaining to the Zion Technical
Specifications was discussed with operating personnel. This item and
the inspector's comment are as follows:
- 5 -
.
Operability of a diesel generator: Is a diesel generator which is
running, loaded, and parallelled to its safety bus considered operable
at the Zion Generating Station while maintenance is being performed on
its air starting system?
Answer: Regarding the Zion diesel generators, the diesels are
considered operable as long as all safety functions can be performed
while running during the maintenance on the air starting system. If the
diesel generator trips during maintenance, a limiting condition for
operation would exist and the diesel generator would not be declared
operable until all maintenance items were completed and a successful
periodic test performed.
8. Testimony Preparation for Spent Fuel Pool Expansion
During the month, written testimony was prepared by the inspector for
the public bearing regarding plans to increase the storage capacity of
the spent fuel pool. In preparation for this hearing the Quality
Assurance, Quality Control and Fuel Handling Departments were
contacted. In addition, a noncompliance history regarding Quality
Assurance at the Zion Generating Station was reviewed and discussed
with other members of Region III office.
No items of noncompliance were identified.
9. Review of Plant Operations
During the month, the inspector made tours of the turbine building,
auxiliary building, control room and the perimeter and security areas.
With regard to the plant, the tours involved valve lineup audits,
review of LCO conditions, discussions with plant operating personnel,
review of station logs, and review of overall plant cleanliness. The
security tours involved witnessing badging vehicle searching, package
surveillance and compliance with station visitor policy.
No items of noncompliance were identified.
10. Plant Maintenance
The inspector either witnessed or reviewed the results of the following
maintenance activities during the month to determine if work control
procedures and required supervision were in effect. The following is a
list of the maintenance activities involved in the review:
a. IM maintenance on MA station 2C FW pump to repair the speed
controller.
- 6 -
.
b. 2A RHR pump seal replacement.
c. Starting air leaks in "0" D/G.
d. B MSIV failure in close from Train A.
e. FW Reg Valve failure to close from Train A.
11. Unresolved Items
Unresolved items are matters about which more information is required
in order to ascertain whether they are acceptable items, items of the
noncompliance, or deviations. Unresolved items disclosed during
inspection are discussed in Paragraphs 2 and 3.
12. Management Interview
A management meeting was held on June 1, 1979, by the resident
inspector with Mr. Wandke and others of his staff in which the results
of the inspection were summarized.
- 7 -
Page Last Reviewed/Updated Tuesday, March 09, 2021
Page Last Reviewed/Updated Tuesday, March 09, 2021