ML20217B800
| ML20217B800 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 02/04/1991 |
| From: | Eapen P, Lopez A, Moy D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20217B791 | List: |
| References | |
| 50-334-90-28, 50-412-90-28, GL-88-17, NUDOCS 9103120232 | |
| Download: ML20217B800 (14) | |
See also: IR 05000334/1990028
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U.S. NUCLEAR REGULATORY COMMISSION
REGION I
Report Nos. 50-334/90-28
50-412/90-28
Docket Nos. 50-334
50-412
License Nos. DPR-66
_NPF-73
Licensee:
Duauesne Light Company
P.O. Boxj
Shioningport. Pennsylvania 15077
Facility Name:
Beaver Valley Power Station. Units 1 and 2
Inspection At:
Shioningoort. Pennsylvania
Inspection Conducted: December 17.1990 - January 25.1991
1[J1 !?/
Inspectors:
721
A. E. Lopegdfea' tor Ege,r'fi'cer( Special
/ Dat/
c
Test Programs Sec ion (EB, DRS
bwq
' 99f9I
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D. T. Moy, React'6r Engine , Special
' Date
Test Programs Section, F
.KE
st/MF/
Approved by:
Dr. P. K. Eapen, Chi'ef, Special Test
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Programs Section, EB, DRS
Insocction Summary: Routine Announced Inspection on December 17. 1990 -
January 25.1991 (Combined Inspection Report Nos. 50-334/90-28. and 50-412/90-28)
Areas Inspected: Licensee actions in response to the " Programmed Enhancements" described
in Generic Letter (GL) 88-17, " Loss of Decay Heat Removal". The inspection reviewed
instrumentation, procedures, Technical Specifications, plant hardware, and plant staff
awareness as related to reduced reactor coolant system (RCS) inventory operation and general
operation of the residual heat removal (RHR) system.
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Results: Generic Letter 88-17 recommendations were implemented with the following
exceptions: (1) Units 1 & 2 - core exit temperature alarms not in place, (2) Unit 1 -
justification for water level instrumentation accuracies and range not in place, (3) Unit 2 -
RCS water level alarms not in place and justification for RCS water level instrumentation
accuracies not in place.
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DETAILS
1.0
Persons Cantac.ted
Duquesne Licht Comnany
- A. Cannizzaro, Operations
J. Forney, I & C
- K. Halliday, NED Manager
H. Kahl, Engineering
- J. Keegan, Operations Procedures
- C. Kuhn, Operations Procedures Engineer
R. Martin, Nuclear Engineering Director
S. Nass, Nuclear Safety
C. O'Neill, Operations Procedures
- M. Pavlick, Director of QS
- F. Schaffner, Operations Procedures Supervisor
- D. Schmitt, ECE Director
- S. Sovick, Senior Licensing Supervisor
- D. Szucs, Licensing Senior Engineer
- N. Tonet, Manager Nuclear Safety
- J. Vassello, Licensing Director
G. Whitmore, Engineering
U.S. Nuclear Regulatory Commission
- ), Beall, Sr. Resident inspector
- P. Wilson, Resident Inspector
- Denotes presence at exit meeting held on December 21,1990.
2.0
Review of Licensee Action in Response to GL 88-17. Loss of Decay Heat Removal
Loss of residual heat removal (RHR) and the consequences of such a loss are of
concern to the NRC. Many such events have occurred during Reactor Coolant System
(RCS) draining, operation in reduced inventory, cr mid-loop condition. (A reduced
RCS inventory condition exists when the RCS water level is lower than a nominal
three feet below the reactor vessel (RV) flange. A mid-loop condition exists when the
actual water level is below the top of the hot leg flow area at the junction of the hot
leg with the RV.) These events often occur when the RCS and containment are both
open. A loss of core radionuclide inventory under these conditions could lead to a
release to the environment.
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GL 8817 informed the licensees of operating pressurized water reactors to respond
with their plans for the following:
a.
A short term program entitled " Expeditious Actions," and
b.
A long-term program entitled " Programmed Enhancements."
The GL stated that the hardware installation and/or modification for the programmed
enhancements, should be implemented:
a.
either by the end of the first refueling outage that is initiated 18 months or
luter following receipt of the letter
b.
or by the end of the second refueling outage following receipt of this letter,
mhichever occurs first.
A shutdown for refueling initiated as of the date of receipt of the letter, was counted
as the first refueling outage, for this purpose.
Programmed enhancements that do not depend upon hardware changes were to be
implemented within 18 months of receipt of the letter. Duquesne Light Company
provided the responses to the expeditious actions and programmed enhancements,
respectively, in letters dated January 13,1989 and February 23,1989.
The NRC staff reviewed the above letters and documented their comments in NRC
letters dated April 11,1989 and January 24,1990, respectively.
The NRC reviewed the implementation of the expeditious actions as detailed in
Inspection Report Nos. 50 334/89-20 and 50-412/89-19. The inspectors found that
the licensee was prepared to implement all Expeditious Actions except for the Unit 1
RCS water level instrumentation. Procedures for installation and calibratio.1 of RCS
level instrumentation were not in place for use during Unit 1 mid-loop operation.
This item remained as an unresolved item (50-334/89-20-01). Based on the evaluation
during the inspection, this item was closed.
The purpose of this inspection was to assess the adequacy of the licensees actions
regarding the programmed enhancements, as detailed below.
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2.1
Instrumentation
A.
Core exit temocrature.
GL 88-17 programmed enhancements recommended at least two reactor vessel
(RV) coolant temperature hdications in the control room (CR) that are
representative of core exit temperature whenever the head is on the RV.
Visible and audible indications of abnormal conditions were recommended.
The licensee response for this recommendation was:
" Procedure revisions are being preparci which will assure at least two
independent temperature measurements representative of the core exit are being
monitored any time the RCS is in a reduced inventory or mid-loop condition
with the reactor vessel head installed. Tnis will be accomplished by using the
core exit thermocouples. The operath.; surveillance logs will require the
operators to record thermocouple readings twice per shift. Additionally, our
abnormal operating procedures will be revised to include a curve of the rate of
RCS temperature rise based on decay heat which will provide the operators
definitive time limits for taking corrective action."
The licensee has provided for temperature indication in the CR during
shutdown operation for both BV1 and BV2 as stated in their above response.
The licensee uses the inlet and outlet temperatures of the RHR heat exchanger
to monitor the RCS temperature. The operators are required to trend at least
two incore thermocouples at a 10 minute interval and to record their values
twice per shift. The inspector noted that there were no alarms, either visible
or audible, in the CR, and there were no plans to add them in the future.
The lack of temperature alarms is not consistent with the position of the GL.
The matter was discussed during the inspection and in a subsequent telephone
conversation with licensee representatives. The licensee agreed to review this
matter for resolution. The licensee orally committed to update their GL
response to further clarify their position.
This item remains unresolved pending licensee resolution of the inconsistency
(Unresolved Item 50-334/90-28-01, 50 412/90-28-01).
.B .
Reactor coolant system water level.
GL 88-17 recommends providing at least two independent RCS water levt.'
indications in the CR. Visible and audible indications of abnormal conditions
are also recommended in the GL.
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The licensee response for the above GL recommendation was: " Modifications
will be completed at each unit to provide two independent RCS level
indications. The target date for Unit No.1 is to complete modifications by the
end of the eighth refueling outage, scheduled to begin April 1,1990, and the
second refueling outage for Unit No. 2, scheduled to begin September 1,1990.
Visible and audible indications of abnormal conditions will be included in any
modifications."
The inspectors observed that the following level monitoring systems are
available at Unit I for mid loop operation:
1.
" Wide-range" tycon tube - One tygon tube is connected roughly at the
bottom of the hot leg with the reference end open to containment near
the top of the pressurizer, It is capable of indication over the range
from the top of the pressurizer to the bottom of the hot leg. There are
no CR alarms for this tygon tube.
2.
Wide-rance level monitor - A wide range level indication in the CR
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indicates between the center line of the hot leg and approximately 21.5
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inches above the RV flange. The range of this monitor is insufficient in
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that the lower level limit for vortexing is 12 inches; 2.5 inches below
the center line of the hot leg. However, Operating Manual (OM) 1.6.4
AQ, instruction step 9 stated that the reactor water level should be
maintained between 20 to 28 inches. The licensee estimates the
accuracy of the instrument to be within 2 inches. A high and low level
alarm annunciator capability is provided in the CR.
3.
Narrow-range ultrasonic sensor - The ultrasonic level sensor is
scheduled for installation on April 1,1991. It is capable of indication
from the top of the hot leg piping (29") to the bottom of the hot leg
piping (0"). The sensitivity of the monitor is i 0.5% inches of water
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or i 2% full scale. The licensee estimates the accuracy to be within
0.5 inch however, the instrument loses its accuracy below 11.6 inches.
Alarm capability will be available in the CR.
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The inspector observed the following level monitoring system at Unit 2:
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1.
Wide-range level monitor - The level monitor is capable of indication
over the range from 107 inches above the RV flange to about the
bottom of the hot leg. The licensee estimates the accuracy to be within
4 inches. There are no audible or visual alarms in the CR for this level
indication.
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2.
Wide-range site glass - The site g! ass is capable of indication over the
same range as the level monitor with an accuracy of 0.5 inch. The site
glass has the same tap as the level monitor. Therefore there is no
independence between the two instruments. There are no audible or
visual alarms in the CR for this level indication.
3.
Wide-range tygon tube - The tygon tube runs along side of the site glass
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with the reference end open to containment near the top of the
pressurizer.
4.
Narrow-range ultrasonic sensor - The ultrasonic level sensor, the same
type of instrument mentioned above for BVI, was scheduled to be
installed during the No. 2 refueling outage. In a letter dated
December 26,1990, Duquesne Light Company (DLC) notified the
NRC of a change in its' schedule to install the ultrasonic level
indication. The vendor had not provided all of the information to
facilitate the installation during the scheduled outage as stated in the
licensee letter dated December 26,1990. The project was then deferred
to the No. 3 refueling outage scheduled to begin in the spring of 1992.
In the interim, DLC committed in the above mentioned letter, not to
enter a reduced inventory condition without first installing the mid-loop
instrt. mentation.
The licensee had not established, at the time of the inspection, the technical
justification for the BV1 wide-range level monitor accuracy and range or for
the BV2 wide-range level monitor accuracy and lack of alarms. The licensee
agreed to provide the technicaljustification in a future letter to the NRC.
This item remains unresolved pending completion of licensee's actions to
establish technical justification for the above items (Unresolved Item 50-
334/90-28-02, 50-412/90-28-02).
C.
Residual Heat Removal (RHR) system monitoring.
GL 88-17 recommended that the licensee establish the capability to
continuously monitor RHR system performance from the CR whenever a RHR
system is being used for cooling the RCS. Visible and audible indications of
abnormal conditions were also recommended.
The licensees response to the above recommendation was:
"In order to monitor performance of the RHR system, when at a reduced RCS
inventory or mid-loop condition, the RHR pump amps will be recorded every
hour to observe trends in RHR performance. Additionally, station surveillance
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logs require recording RHR flow twice per shift. These parameters along with
recording RHR temperature as discussed above should provide the operators
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with sufficient information to detect the onset of a malfunction."
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The inspector verified the RHR system monitoring and found it consistent with
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the recommendations of GL 88-17. The RHR system flow rates, RHR pump
amps, and RHR heat exchanger inlet and outlet temperatures are displayed in
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the CR. There are audible and visual alarms for the RHR pump discharge
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pressure high, RHR pump discharge pressure low, and for the auto stop of the
RHR pump.
2.2
Procedures
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GL 88-17 recommended procedures and controls to cover both normal and off-
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normal operation during reduced inventory operation and the establishment of
the basis for entry into a reduced inventory condition. These procedures were
to cover operation of the NSSS, the containment, and supporting systems under
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conditions for which cooling would normally be provided by RHR systems,
The licensees response to this recommendation was:
"The Westinghouse Owners Group is developing a background document
which will provide the basis for procedures controlling operation at reduced
RCS inventory. When this document is published, it will be reviewed against
activities taken thus far and prograrn changes will be made where it is
appropriate to do so.
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We are currently revising procedures addressing normal and off-normal plant
operations when entering in a reduced inventory condition.
These include:
Reduced RCS Inventory Operation Checklist; this provides instructions
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to establish and maintain administrative controls specific to activities
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that may perturb the RCS water level while the RCS is operated at
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reduced RCS inventory of midloop conditions.
Draining the RCS to Reduced Inventory of Midicop Operation; this
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provides the instructions to drain the RCS to lower than 3 feet below
the reactor vessel flange or to the mid-loop level.
RCS Makeup from the Refueling Water Storage Tank (RWST); this
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provides the instructions for makeup by gravity flow from the RWST
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through the charging pumps to the RCS.
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RHR System Operation with RCS at Reduced Inventory or Midloop
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Condition; this provides the special operating conditions necessary
when the RCS is partially drained to a reduced inventory condition or to
the mid-loop level.
Prerequisites for Entering a F Wuced RCS Inventory or Mid-loop
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Condition; this is to establish and maintain conditions to meet the
commendations of NRC Generic Letter 88-17.
Residual Heat Removal (RHR) System Loss; This provides instructions
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to the operator to monitor system parameters and to restore RCS
cooling upon loss of RHR.
Loss of RHR While at Reduced RCS Inventory of Mid-loop Condition;
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this provides the actions necessary for maintaining core cooling and to
protect the reactor core in the event that RHR cooling is lost during
reduced RCS inventory of mid-loop condition.
Containment Integrity Checklist for Refueling; to verify and maintain
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containment closure prior to entering a reduced RCS inventory or mid-
loop condition.
Station Surveillance Logs; these are intended for use during operation
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with the RCS at a reduced inventory or mid-loop condition and
monitors important plant parameters.
These procedures will be in place prior to entering a reduced RCS inventory or
mid-loop condition. Changes to these procedures will be made as new
information becomes available and any plant modifications related to this
operating condition are completed."
The above procedures were reviewed and found to adequately meet the
recommendations of GL 88-17.-
2.3
Analyses
GL 88-17 recommended analyses to provide a basis for procedures,
instrumentation installation and response, an('
alpment/NSSS interactions and
response. A complete understanding of NSS5
1avior under shutdown
operation was indicated to be the objective.
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The licensees response to this recommendation stated:
"Duquesne Light Company is a member of the Westinghouse Owners Group.
As such, we have received those outputs issued from their analysis program
which is intended to address this recommendation. We will continue to follow
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efforts in this area and implement those changes which we determine to be
program enhancements.
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Additionally, a plant specific analysis was performed for both Unit No. I and
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No. 2 which determined RCS heatup rates and RCS boiloff rates versus time
after reactor shutdown. This analysis considered various RCS water levels. It
also included several different system ar angements, including both hot and
cold leg openings.
The results from these analyses will be incorporated into the Unit No. I and
Unit No. 2 procedures, as appropriate, to address the DHR and reduced
inventory operations."
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During the inspection, the inspectors observed that Westinghouse Electric
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Corporation has prepared an analytical report for use by members of the
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Westinghouse Owners Group. This report deals with the phenomena of air
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ingestion into the RHR system during non-power mid loop operat on.
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Duquesne Light personnel are clearly familiar with the Westinghouse Owners
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Group analyses (WCAP 11916) ar.d have used this guideline to develop mid-
loop calculations for BV1 and BV2.
The inspector reviewed the thermal-hydraulic analyses, performed by the
licensee to predict RCS behavior following the loss of RHR system cooling
during mid-loop operations. The inspector randomly selected the following
thermal-hydraulic calculations for mid-loop operation review:
1.
Calculation No. 8700-DMC-2393, " Maximum RHR drain down rate
versus reactor cavity water level," Rev. O, dated June 1,1990,
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Calculation No.10080-DMC-0015, " Loss of RHR with reduced
inventory analysis," Rev.1, dated October 8,1989. This calculation
analyzed the plant specific core heatup and boil-off rates as a function
of reactor coolant system volume and time since reactor shutdown.
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Calculation No.10080-DMC-0016, " Unit 2 - Required RCS hot leg
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water level reading from (2RCS-' .T-102) during RCS mid-loop
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operation," Rev. O, dated January 24, 1989.
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Calculation No. 8700-DMC-2279, " Unit 1 - Required RCS water level
indications on level instruments (PT-RC-414, 415, 416, or 434) during
mid-loop operation," Rev. O, dated July 24, 1989.
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The inspector reviewed the above calculations and found them to be
acceptable.
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The inspector further verified that the results of the above calculations are
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being used in the Abnormal Operating Procedures (AOPs). The AOPs
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incorporate the thermal hydraulic analyses with the exception of AOP !.10.2
and AOP 2.10.2, " Loss of RHR while at reduced inventory or mid-loop
condition." The boil-off rate curve is attached to the AOP procedures,
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however, none of the actions or steps within 'he AOPs used the boil-off rate
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curve to mitigate the event. The inspector brought this matter to the licensees
attention and they promptly issued an Operating Manual Deficiency Report for
both units AOPs to correct the deficiencies. The inspec:or has no further
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concerns regarding this matter.
2.4
RCS Perturbations
The GL 88-17 recommended in the expeditious actions that the licensee
implement procedures and administrative controls that generally avoid
operations that deliberately or knowingly lead to perturbations to the RCS
ar.d/or to systems that are necessary to maintain the RCS in a stable and
controlled condition while the RCS is in a reduced inventory condition. The
dRC reviewed the licensees actions with regard to the above in Inspection
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Report Nos. 50-314/89-20 and 50-412/89-19 and found that the licensee had
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implemented procedures and administrative controls to preclude operations that
would lead to perturbations in the RCS.
The GL also recommended in the programmed enhancements that the licensee
reexamine the expeditious action regarding RCS perturbations and to refine
operations as necessary to reasonably minimize the likelihood of loss of DHR.
The licensee response to this recommendation stated:
"Those activities identified in our response to your recommended expeditious
actions have been re-examined for insorporation as a programmed
enhancement. We believe the activities described therein will reasonable
minimize the likelihood of loss of DHR. Therefore, no further actions are
planned at this time.
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There are, however, certain licensing actions that may result in additional mid-
loop operations. We are continuing to work with the NRC for an appropriate
resolution for alternatives to check valves' disassembly to minimize the need
for mid-loop operation."
The inspectors verified that the licensee has implemented procedures and
administrative controls to preclude operations that would lead to perturbations
in the RCS. Procedures 1.6.4 AP (BVI) and 2.6.4 V (BV2), " Reduced RCS
Inventory Operation Checklist" establishes administrative controls for all
personnel involved in requesting, implementing, reviewing, working or
authorizing activities that may affect or perturb the RCS water level while the
RCS is operating at reduced inventory /mid-loop condition. These procedures
provide a list of boundary valves between the RCS, RHR; and CVCS that, if
opened, may cause a perturbation of RCS level. This procedure also provides
a list of procedures from various station groups, whose operation may perturb
the RCS level. The Nuclear Control Operator and the Senict Reactor Operator
are responsible for completing this procedure prior to enterirg reduced
inventory of mid-loop operation and when reviewing and p:epariig
Valve / Switching Procedure forms.
The procedures and administrative controls established we e fo:.c
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consistent with the programmed enhancements described in GL 88-17.
2.5 '
Eauioment and RCS Inventory Control
GL 88-17 recommended in the expeditious actions that the licensee provide at
least two available, operable means of adding inventory to the RCS that are in
addition to pumps that are a part of the normal DHR systems. The inspectors
verified in Inspection Report Nos. 50-334/89-20 and 50-412/89-19, that the
licensee complied with the recommendations of the GL.
GL 88-17 also recommended in the programmed enhancements that the
licensee assure that adequate equipment of high reliability was provided for
cooling the RCS and for avoiding a loss of RCS cooling. At least two means
of adding inventory to the RCS that are in addition to normal SDC systems
were to be provided. One should be a high pressure safety injection pump or
an equally effective and reliable means of injecting water. Water addition rate
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should be sufficient to keep the core covered while taking into account water
losses due to the RCS configuration and the water injection location.
The licensee response to this recommendation stated:
"Two available means of adding inventory to the RCS exists as described in
our response to your recommended expeditious actions.
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In addition to the above, procedures will be in p; ace prior to entering a drained
down condition to provide a gravity makeup to the RCS and the use of a steam
generator that would provide reflux cooling in the event of core uncovery.
The method of makeup to the RCS will be selected based on plant conditions.
Procedures will direct operators to the best method for any plant condition.
Equipment for which credit is being taken for cooling the RCS and for
avoiding a loss of RCS cooling will be of high reliability and will have
redundancy.
Those critical plant activities involving monitoring of instrumentation, outside
the control room, will be provided with adequate communications."
The inspectors verified that the licensee has procedures and administrative
controls (Operating Manual 1.6.4 AQ (BV1) and 2.6.4 U (BV2)) to provide at
least two means of adding inventory to the RCS The two available sources of
RCS inventory addition are one high head safety injection pump and one 'w
head safety injection pump. Further, a minimum of two steam generators
provided (OST 2.6.11). Each injeGion flow path will provide sufficient flow
to keep the core covered. The inspectors verified that the water flow path for
these injection systems does not bypass the reactor vessel.
Based on the above, the inspectors concluded that the licensee actions in this
matter are consistent with the actions described in GL 88-17 and had no further
questions concerning this functional area.
2.6
Technical Specifications
Technical specifications that restrict or limit the safety benefit of the actions
identified in GL 88-17 sho>ild have been identined and appropriate changes
submitted to NRC for 3pproval.
The licensee response to this recommendation stated:
"We reviewed both units' Yechnical Specifications agat st the activities planned
to address reduced RCS it:ventory operation. There are no Technical
Specifications that restrict or limit the safety benefit of the actions identified;
therefore, no cinnges are neeAed."
The inspectors independently veritied that no changes were necessary in the BV
technical specifications for mid-loop operation.
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2.7
Engineering Support for Mid-loop Operations
The licensee committed to install the RCS level indication modification by the
No. 2 refueling outage for Unit 2, which was scheduled to begin on :ptember
1,1990. At the time of this inspection (12/17/90), the RCS level inaication
was not inctalled. As indicated by the licensee, this delay was a result of
insufficient documentation from the vendor to support the installation. Some
examples of incomplete vendor documentation include: partial vendor
technical manual, incorrect equipment drawing, and missing certificate of
conformance. This suggests that the licensees' control for vendor support for
this modification wat less than adequate. Therefore, the inspectors concluded
that the licensees' engineering support on the installation of the RCS level
indication modification was not timely er adequate to meet the schedule.
3.0
Exit and Management Meeting
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At the conclusion of the site inspection, on December 21,1990, an exit interview was
conducted with the licensee's senior site representatives (denoted in Section 1) to
discuss the results and conclusions of this inspection.
Subsequent to the exit meeting, on January 3,1991, a telephone conversation was held
between the NRC and licensee representatives The licensee agreed to review the
Beaver Valley response to Generic Letter 88-17 and to have available, adequate
technical basis to justify the differences between the GL recommendations and the BV
response and actions.
At no time during this inspection was written material provided to the licensee by the
inspector. The licensee representatives did not indicate that this inspection involved
proprietary information.