IR 05000267/1986010
| ML20198J760 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 05/26/1986 |
| From: | Farrell R, Jaudon J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20198J740 | List: |
| References | |
| TASK-2.E.4.1, TASK-TM 50-267-86-10, NUDOCS 8606030203 | |
| Download: ML20198J760 (7) | |
Text
.
.
. _.
--.
-.
APPENDIX U. S. NUCLEAR REGULATORY COMMISSION
- -
REGION IV
NRC Inspection Report: 50-267/86-10 License:
DPR-34 Docket: 50-267
Licensee:
Public Service Company of Colorado (PSC)
P. O. Box 840
Denver, Colorado 80201
"
Facility Name:
Fort St. Vrain Nuclear Generating Station Inspection At:
Fort St. Vrain (FSV) Site, Platteville, Colorado Inspection Conducted: March I through April 30, 1986
N$
'
i Inspector:
'
-
-
R. E. Farre*l, Senior Residen ector (SRI)
Date
'
Approved: C.
-
(f<
MS Md (3..Q.J d'on, Chief i
Date YroJect Section A Inspection Summary Inspection Conducted March 1 through April 30, 1986 (Report 50-267/86-10)
,
Areas Inspected: Routine, unannounced inspection of operational safety verification, onsite followup of operating events, TMI action items, surveil-lance testing, engineered safety features, offsite review committee, and security.
Results: Within the seven areas inspected, no violations or deviations wero
,
identified.
.
8606030203 860530 PDR ADOCK 05000267 G
PDR i
,
. - -. -
-
,-
- -, - -, -, -,.,. - -
-
- - -. -. = - - - -,, -,.
-- --
r -
n, e-
-
,-,,,
-
.
..- -.
_
. -
.._-- -
_
DETAILS 1.
Persons Contacted d
.
Principal Licensee Employees D. Alps, Security Supervisor
- T. Borst, Support Services Manager / Radiation Protection Manager R. Craun, Site Engineering Manager M. Deniston, Shift Supervisor D. Evans, Superintendent, Operations
- M. Ferris, QA Operations Manager
- C. Fuller, Station Manager
- S. Hofstetter, Nuclear Licensing Engineer
- J. Gahm, Manager, Nuclear Production
- F. Novachek, Technical / Administrative Services Manager T. Prenger, QA Services Manager
- L. Singleton, Manager, QA D. Warembourg, Manager, Nuclear Engineering The SRI also contacted other licensee and contractor personnel during the inspection.
- Denotes those attending the exit interview conducted May 2, 1986.
2.
Operational Safety Verification The SRI reviewed licensee activities to ascertain that the facility is being operated safely and in conformance with regulatory requirements and that the licensee's management control system is effectively discharging its responsibilities for continued safe operation.
The review was conducted by direct observation of activities, tours of the facility, interviews and discussions with licensee personnel, independent verifications of safety system status and limiting conditions for operations, and review of facility records.
Logs and records reviewed included:
Shift supervisor logs
,
.
Reactor operator logs
.
Equipment operator logs
.
Auxiliary operator logs
.
Technical specification compliance logs
.
,
,
-
-
e
,--- -
- --
---w
,
w,o e
-
-
w,,
,na x
w A
-
m ym q
m - -,
e
.. _.
.
.
_.
_-
. - _ _
.
_ _ _ _
_ -
,
Operations order book
.
Operations deviations reports
.
Clearance log
.
Temporary configuation reports
.
Station service requests (SSR)
.
During tours of accessible areas, particular attention was directed to the following:
Monitoring instrumentation
.
Radiation controls
.
Housekeeping
.
Fluid leaks
.
Piping vibrations
.
Hanger / seismic restraints
.
Clearance tags
.
Fire hazards
.
'
Control room manning
.
.
On Friday, April 11, the turbine generator was synchronized to the grid for the first time since June 1984.
The plant has since been operating at approximately 34.5% power (restricted to 35% power operation until satisfactorily meeting the requirements of 10 CFR 50.49, environmental qualification of equipment).
A power level of 35% is approximately equivalent to a net electrical output of 80 megawatts electrical.
No violations or deviations were identified in this inspection area.
3'.
Onsite Followup of Operating Events i
a.
Degraded Offsite Power l
During the evening of April 2, continuing throughout the day of
April 3, the plant withstood one of the worst snow storms in Colorado's history.
The storm delivered a large quantity of extremely wet snow which collected on transmission lines and distribution lines throughout the licensee's electrical system.
The weight of the snow, i
,.., _, _ _ _ _ _ _ _ _ _
_ _.., _ _,. - _
_.
._
.__.
_
~.____
-
. _. _ _,
j
-
.-.
-
-
.
- - -
--
.
. __
increased surface area due to snow on the cables, and high winds caused transmission and distribution lines throughout the system to fail. Continued sporadic grounding of transmission lines led to system voltage and frequency instabilities. The plant has five
..
outside sources of power coming into the switchyard and at no time suffered a complete loss of offsite power. However, starting on the morning of April 3rd and continuing through April 4th and 5th, the plant lost a phase at a time of one or more sources of offsite power
]
causing equipment to trip on protective relays. At no time did the plant completely lose offsite power or suffer a degraded voltage or frequency condition for a sufficient length of time to automatically start the diesel generators.
The plant manager, who remained onsite throughout the duration of the storm and the degraded offsite power condition, made the decision very early into the event to place the plant in a safe shutdown condition,
and caused the plant to be manually scrammed from approximately 26%
power. The diesel generators were not started since oparating the diesel for long duration at idle is considered detrimental to the
,
engines and loading the diesels would require separating from the
offsite grid since paralleling the diesels to the grid would cause loss of the diesels if the grid experienced an undervoltage or underfrequency condition. Offsite power is the preferred source of power for safety-related equipment, the plant manager's actions kept the plant on the preferred source of power and maintained the diesel i
generators as a backup source of power consistent with the plant
'
design and NRC guidance.
b.
Unplanned Release
During the grid instability of April 3,1986, discussed above, an unplanned release of radioactive gases occurred. This release was the result of intermittent losses of bearing water pumps and buffer helium
,
to the gas circulators. When bearing water is lost to a gas circulator, the circulator shuts down.
During the shutdown, if there is an interruption of buffer helium, primary coolant helium can leak
,
down the circulator shaft unti! the shutdown seals are set. When
'
helium leaks down the shaft, it mixes with exhausting reheat steam used to drive the circulator. A release path for the helium and
,
entrained noble gases is thus possible through the main condenser and
'
'
air ejectors to the plant stack. The licensee calculated that the release was not greater than 96 millicuries of noble gas. This was based on the highest radiation reading on the plant stack monitor for the time periods involved. A release of 96 millicuries of noble gas is within Technical Specification limits for planned releases, and it
.
does not present an apparent danger to public health. The licensee,
'
however, declared an unusual event because of the unplanned nature of j
the release.
J l
,. -- -- ~ ~ ~ - -
,, -
_
,
,
- - - -
--
- - - -
. - - - - - - -,, -, -
-
. _ - _
_
_
_ _ _ _
..-___.
__
..
_ _ _ _ _ _.__
__
T
)
c.
Control Rod Drop
i l
At 0220 hours0.00255 days <br />0.0611 hours <br />3.637566e-4 weeks <br />8.371e-5 months <br /> MST on April 23, 1986, with the reactor at 34% power and in automatic control (all systems follow main steam temperature demand) the plant experienced a control rod drop. The FSV plant has
,
37 control rods, 36 of which are used as shim and 1 (the center rod)
used as a regulating rod.
With the reactor at 34% power in auto
,
control, the regulating rod received a withdrawal signal.
The rod
,
responded to the signal, the rod brake failed to reset following rod
'
movement and the rod fell from 116 inches out to 77 inches out reducing reactor power from 34% to 27%.
The senior reactor operator on duty took immediate action, transferring the reactor from auto control to manual control and set the brake on the regulating rod.
Shim rods were then withdrawn restoring power to 34% and an
!
electrician on duty was dispatched to trouble shoot the control rod drive circuitry of the regulating rod.
A loose wire powering the regulating rod brake was found in the motor control center and was l
repaired.
The regulating rod was functionally tested and responded as designed.
The regulating rod was at this time considered operable and
,
the rod pattern was restored to normal.
As a followup, the next day the plant utilized a thermograph; this is J
a device which identifies small temperature differences in circuitry caused by arcing across loose wire connections.
This device is used to scan a circuit box and identify any loose connections.
All 37 control rod drive circuitry cabinets were scanned with the thermograph, and no additional loose wires were identified.
!
No violations or deviations were identified in this inspectior area.
4.
TMI Action Items (Dedicated Hydrogen Containment Penetrations)
!
(CLOSED) TMI, Item II.E.4.1 Dedicated Hydrogen Penetrations
'
l This item does not pertain to the FSV reactor. This item requires dedicated containment penetrations for hydrogen monitors and recombiners to monitor and dispose of hydrogen resulting from a water / fuel cladding reaction following a postulated loss of coolant accident in a light water cooled nuclear reactor.
FSV is a helium cooled reactor utilizing carbide encased fuel.
There is no water or metal fuel cladding in the FSV reactor and consequently no hydrogen following a postulated loss of coolant accident.
Consequently, dedicated hydrogen penetrations are not required at FSV.
!
No violations or deviations were identified in this inspection area.
5.
Surveillance Testing The FSV facility utilizes a prestressed concrete reactor vessel.
This vessel is encircled by circumferential and longitudinal prestressing tendons as well as tendons crossing the bottom and top pressure vessel r
!
- - - - - - - - - - -.
-
-~
, - - -
-.., -. -.. - - _ _
_ -__
_ _ - - -.
_._
______
_.
__
_. _ _
__
_
_
_ _. - -
heads.
The licensee has an active vessel tendon surveillance program.
During the inspection period, a circumferential tendon, Tendon CM4.6, was visually inspected and found to be missing 2 wire buttons with an additional 18 buttons popped off of the total of 179 buttons.
This number of degraded tendon wires is within the design tolerance for the tendon to still be considered operable.
Additionally, the tendon tube was found to
'
.
contain approximately 25 gallons of water.
Samples of this water were subjected to analysis in the chemistry and radiochemistry departments.
To
!
date, no source of the water has been determined; however, due to the lack of additives present in this water that are present in the pressure vessel liner cooling system water, the licensee reached the initial conclusion
<
that the presence of water in this tendon tube was not indicative of a pressure vessel liner cooling water leak.
The licensee is continuing to try to identify the source of the water and believes that the water may have been present since the original construction of the plant.
,
'
,
The NRC SRI witnessed a lift off test on one end of the circumferential tendon (the other end is not physically accessible for a liftoff test).
The test was used to determine how much prestress load the tendon is carrying.
Licensee engineering and quality control personnel were present for the test and the tendon was performing as designed.
No violations or deviations were identified in this inspection area.
6.
Engineered Safety Features Systems During this inspection period the FSV turbine generator was synchronized to
l the licensee's grid for the first time since June 1984.
The NRC SRI paid particular attention to the readiness to start and electrical alignments of
'
the emergency diesel generators.
At no time were the diesel generators identified in a configuration other than ready to automatically start and load if needed.
Additionally, the automatic cooling mode (ACM) diesel was
'
verified as being operable if called upon to assist in placing the plant in a safe shutdown condition.
The ACM is an extra diesel generator which, if needed, is manually started and aligned to power various combinations of
!
pumps to cool the reactor vessel liner removing decay heat and to supply motive force to the helium circulators maintaining forced circulation of the reactor coolant.
,
'
No violation or deviations were identified in this inspection area.
7,.
Offsite Review Function The offsite review function, called the Nuclear Facility Safety Committee
,
by the licensee, was inspected by Regional inspectors (NRC Inspection i
.
Report 50-267/86-08) during this inspection period.
However, during NRC Inspection Report 86-08 no NFSC meeting was conducted.
Consequently, the SRI attended the next NFSC meeting held on site.
The meeting was chaired by the alternate committee chairman; there was a quorum present; and the meeting was conducted in accordance with a printed agenda.
Items before the committee were discussed prior to committee votes being taken.
The i
.,.
-
_ _. _ _ _
. _.., _
- _ _ _ _
_.
_
..
.. _,, _ _, -. _. _, _
_
, _,, _.
_.
_ _ _ _ _ _ _
..
committee appeared to be well informed and knowledgeable of those items before the committee for action.
No violations or deviations were identified in this inspection area.
'
8.
' Security The SRI on randomly selected nights walked the perimeter of the protected area during the back shifts. All guard posts appeared to be manned by alert, attentive personnel. Additionally, the lead security officer and watch commander were observed to be periodically checking guard posts.
No violations or deviations were identified in this inspection area.
9.
Exit Meeting l
The SRI conducted an exit meeting on May 2, 1986, with the licensee personnel indicated in paragraph 1.
At this time the SRI reviewed the scope and findings of the inspection.
.
-
.
_. _ _ -. _ _ -