ML20214W310
| ML20214W310 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 12/05/1986 |
| From: | MISSISSIPPI POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML20214W297 | List: |
| References | |
| TAC-62754, TAC-63054, NUDOCS 8612100169 | |
| Download: ML20214W310 (6) | |
Text
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REACTIVITY CONTROL SYSTEMS ROD PATTERN CONTROL SYSTEM LIMITING CONDITION FOR OPERATION 3.1.4.2 The rod pattern control system (RPCS) shall be OPERABLE.
APPLICABILITY:
OPERATIONAL CONDITIONS 1 and 2*#
o ACTION With the RPCS inoperable or with the requirements of ACTION b, below,
)
a.
not satisfied and with:
g 1.
THERMAL POWER less than or equal to the Low Power Setpoint,
.I control rod movement shall not be permitted, except by a scram.
3 j
2.
THERMAL POWER greater than the Low Power Setpoint, f
control rod withdrawal shall not be permitted.
3 b.
"ith :n ing r:ble centr:1 red (:)f OPERABLE control rod movement may
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. continue by bypassing th: 'nep:r:bl: control rod (s) in the RPCS**
provided that:
1.
With one control rod inoperable due to being immovable, as a result of excessive friction or mechanical interference, or known to be untrippable, this inoperable control rod may be bypassed in the rod action control system (RACS) provided that the SHUTOOWN MARGIN has been determined to be equal to or greater than required by. Specification 3.1.1.
2.
With up to eight control rods inoperable for causes other than addressed in ACTION b.1, above, these inoperable control rods
.may be bypassed in the RACS provided that:
a)~
The control rod (s) to be bypassed is inserted and the p
directional control valves are disarmed either:
1)
Electrically, or
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.2)
Hydraulically by closing the drive water and exhaust
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water isolation valves.
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b)
All inoperable control rods are separated from all other i
inoperable control rods by at least two control cells in all directions.
.2-c)
There are not more than 3 inoperable control rods in
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any RPCS group.
o,nd. subsepent positioning
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INSERT Y
'b f/.
The position and bypassing of :n 'n:p:r:51: control rod (s) is verified by a second licensed operator or other technically eneo 08' qualified member of the unit technical staff.
58 mo "See Special Test Exception 3.10.2
- Entry into OPERATIONAL CONDITION 2 and withdrawal of selected control rods is permitted for the purpose of determining the OPERABILITY of the RPCS prior gg to withdrawal of control rods for the purpose of bringing the reactor to o<
y criticality.
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- Bypassing control rod (s) in the RPCS shall be ~ performed under administrative control.
GRAND GULF-UNIT 1 3/4 1-16 Amenclment No. -
INSERT for 3.1.4.2; page 3/4 1-16 Y
3.
Control rods may be bypassed in the Rod Action Control System (RACS) at 7
any time. However, if THERMAL POWER is less than or equal to 20% of RATED R
THERMAL POWER:
1 a)
All 'out-of-sequence and/or inoperable control rods must be separated
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from all other out-of-sequence and/or inoperable control rods by at least two control cells in all directions.
b)
There may not be more than three out-of-sequence and/or inoperable i
control rods in any RPCS group.
,f.
t c)
Only one bypassed control rod may be moved at a time.
d)
A maximum of 8 control rods may be bypassed and/or out-of-sequence at a time.
e)
Control rods may not be bypassed and subsequently withdrawn past j
their in-sequence positions, f)
Any control rod found to be withdrawn past its in-sequence position must be inserted to or beyond its in-sequence position prior to subsequent control rod movement.
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J13TS86112001 - 3
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REACTIVITY CONTROL SYSTEMS SURVEILLANCE REQUIREMENTS 4.1.4.2 The RPCS shall be demonstrated OPERABLE by: verifying the CPERf3ILITY A
cf the:
Ver*hins the OPERASILITY of the
- /odpatterncontrollerfunctionwhenTHERMALPOWERislessthanthe lg a.
low power setpoint by selecting and attempting to move an inhibited control rod:
1.
After withdrawal of the first insequbnce control rod or gang for each reactor startup.
2.
As soon as the rod inhibit mode is automatically initiated at the RPCS low power setpoint, 20 +15, -0% of RATED THERMAL POWER, during power reduction.
3.
The first time only that a banked position, N1, N2, or N3, is reached during startup or during power reduction below the RPCS low power setpoint.
Verifying the OPERABILITY of the b.
+p'od withdrawal limiter function when THERMAL POWER is greater than lw or equal to the low power setpoint by selecting and attempting to g
move a restricted control rod in excess of the allowable distance:
1.
As each power range above the RPCS low power setpoint is entered during a power increase or decrease.
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2.
At least once per 31 days while operation continues within a y
given power range above the RPCS low power setpoint.
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u.ri-b passeol.
T b po.ss swite.h is in the C.
Veri 9pn3 es.ch RPCS 3
3 or is in C.cm plianc.e w ith AcTio# b.3 of this
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position s p e.tih~c.oAion :
[a.
1.
At leo st once per %4 hou.rs.
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2,.
Prer to control rod. rnovernent, except g serarn,.
Sollowihg a power r ede.ction to less than or epal Eo the low power S et. point,
3 Arnenbent Mo -
GRAND GULF-UNIT 1 3/4 1-17
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REACTIVITY CONTROL SYSTEMS BASES CONTROL RODS (Continued)
Control rod coupling integrity is required to ensure compliance with the analysis of the rod drop accident in the FSAR.
The overtravel position feature provides the only positive means of determining that a rod is properly coupled and therefore this check must be performed prior to achieving criticality after completing CORE ALTERATIONS that could have affected the control rod coupling integrity.
The subsequent check is performed as a backup to the initial demonstration.
In order to ensure that the control rod patterns can be followed and therefore that other parameters are within their limits, the control rod position indication system must be OPERABLE.
The control rod housing support restricts the outward movement of a control rod to less than 3 inches in the event of a housing failure.
The amount of rod reactivity which could be added by this small amount of rod withdrawal is less than a normal withdrawal increment and will not contribute to any damage to the primary coolant system.
The support is not required when there is no pressure to act as a driving force to rapidly eject a drive housing.
The required surveillance intervals are adequate to determine that the rods are OPERABLE and not so frequent as to cause excessive wear on the system components.
3/4.1.4 CONTROL ROD PROGRAM CONTROLS The rod withdrawal limiter system input power signal orginates from the first stage turbine pressure. When operating with the steam bypass valves open, this signal indicates a core power level which is less than the true core power.
Consequently, near the low power setpoint and high power setpoint of the rod pattern control system, the potential exists for nonconservative control rod withdrawals. Therefore, when operating at a sufficiently high power level, there is a small probability of violating fuel Safety Limits during a licensing 4
basis rod withdrawal error transient. To ensure that fuel Safety Limits are 4
not violated, this specification prohibits control rod withdrawal when a f
biased power signal exists and core power exceeds the specified level.
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Control rod withdrawal and insertion sequences are established to assure 3
that the maximum insequence individual control rod or control rod segments which are withdrawn at any time during the fuel cycle could not be worth enough to d
result in a peak fuel enthalpy greater than 280 cal /gm in the event of a control vi rod drop accident.
The specified sequences are characterized by homogeneous, y
scattered patterns of control rod withdrawal. When THERMAL POWER is greater than 20% of RATED THERMAL POWER, there is no possible rod worth which, if dropped Q
at the design rate of the velocity limiter, could result in a peak enthalpy of t
280 cal /gm.
Thus requiring the to be OPERABLE when THERMAL POWER is less l%
than or equal to 20% of RATED THERMA POWER provides adequate control, rod pattern controller kneun GRAND GULF-UNIT 1 B 3/4 1-3 Amendment Alo -
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1 REACTIVITY CONTROL SYSTEMS BASES y
i CONTROL ROD PROGRAM CONTROLS (Continued)
The RPCS provides automatic supervision to assure that out-of-sequence rods will not be withdrawn or inserted. *lNSERT I
The analysis of the rod drop accident is presented in Section 15.4 of the FSAR and the techniques of the analysis are presented in a topical report, Reference 1, and two supplements, References 2 and 3.
The RPCS is also designed to automatically prevent fuel damage in the event of erroneous rod withdrawal from locations of high power density during higher power operation.
A dual channel system is provided that, above the low power setpoint, restricts the withdrawal distances of all non peripheral control rods. This restriction is greatest at highest power levels.
3/4.1.5 STANDBY LIQUID CONTROL SYSTEM The standby liquid control system provides a backup capability for bringing the reactor from full power to a cold, xenon-free shutdown, assuming that the withdrawn control rods remain fixed in the rated power pattern. To meet this objective it is necessary to inject a quantity of boron which produces a concen-tration of 660 pp.n in the reactor core in approximately 90 to 120 minutes.
A minimum available quantity of 4587 gallons of sodium pentaborate solution containing a minimum of 5500 lbs. of sodium pentaborate is required to meet a shutdown requirement of 3L There is ar. additional allowance of 165 ppm in the reactor core to account for imperfect mixing and the filling of other piping systems connected to the reactor vessel.
The time requirement was selected to override the reactivity insertion rate due to cooldown following the xenon poison peak and the required pumping rate is 41.2 gpm. The minimum storage volume of the solution is established to allow for the portion below the pump suction that cannot be inserted.
The temperature requirement is necessary to ensure that the sodium pentaborate remains in solution..
l With redundant pumps and explosive' injection valves and with a highly j
reliable control rod scram system, operation of the reactor is permitted to continue for short periods of time with the system inoperable or for longer periods of time with one of the redundant components inoperable.
Surveillance requirements are established on a frequency that assures a high reliability of the system.
Once the solution is established, boron con-centration will not vary unless more boron or water is added, thus a check on l
the temperature and volume once each 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> assures that the solution is avail-I able for use.
l Replacement of the explosive charges in the valves at regular intervals will i
assure that these valves will not fail because of deterioration of the charges.
1.
C. J. Paone, R. C. Stirn and J. A. Woolley, " Rod Drop Accident Analysis for Large BWR's," G. E. Topical Report NE00-10527, March 1972 2.
C. J. Paone, R. C. Stirn and R. M. Young, Supplement 1 to NEDO-10527, July 1972 3.
J. M. Haun, C. J. Paone and R. C. Stirn, Addendum 2, " Exposed Cores,"
Supplement 2 to NEDO-10527, January 1973 Amendmed /YA -
GRAND GULF-UNIT 1 B 3/4 1-4
INSERT for Bases 3/4.1.4; page B 3/41-4 A rod is out-of-sequence if it does not meet the criteria of the Banked Position Withdrawal Sequence as described in the FSAR. The RPCS function is f
allowed to be bypassed in the Rod Action Cor. trol System (RACS) if necessary.
for example, to insert an inoperable control rod, return an out-of-sequence y
control rod to the proper in-sequence position or move an in-sequence control y
rod to another in-sequence position. The requirement that a second qualified t
individual verify such bypassing and positioning of control rods ensures that
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the basis for RPCS limitations are not exceeded.
In addition if THERMAL POWER x
is below the low power setpoint, additional restrictions are provided when 3
bypassing control rods to ensure operation at all times within the basis of the a
control rod drop accident analysis.
J13TS86112001 - 4