ML19312B971
| ML19312B971 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/09/1975 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML19312B965 | List: |
| References | |
| NUDOCS 7911270753 | |
| Download: ML19312B971 (14) | |
Text
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O 313 "1 1 e ce aitie e 1er critic 11ev Shecification 3.1.3.1 The re. actor coolant temperature shall be above 525 F except for portions of low power physics testing when the requirements of Specification 3.1.9 shall apply.
3.1.3.2 Reactor coolant temperature shall be above DTT + 10 F.
3.1.3.3 When the reactor coolant temperature is below the minimum temperature specified in 3.1.3.1 above, except for portions of low power physics testing when the requirements of Specification 3.1.9 shall apply, the reactor shall be suberitical by an amount equal to or greater than the calculated reactivity insertion due to depressurization.
3.1.3.4 The reactor shall be maintained suberitical by at least 1%Ak/k until a steam bubble is formed and a water level between 80 and 396 inches is established in the pressurizer.
3.1.3.5 Except for physics tests and as limited by 3.5.2.1, safety rod groups shall be fully withdrawn prior to any other reduction in shutdown margin by deboration or regulating rod withdrawal during the approach to criticality.
The regulating rods shall then be positioned within their position limits defined by Specification 3.5.2.5 prior to j
deboration.
Bases At the beginning of the initial fuel cycle, the moderator temperature coefficient is expected to be slightly positive at operating temperatures with the operating configuration of control rods.(1) Calculations shcw that above 525 F, the con-sequences are acceptable.
Since the moderator temperature coefficient at lower temperatures will be less negative or more positive than at operating temperature,(2) startup and operation of the reactor when reactor coolant temperature is less than 525 F is prohibited except where necessary for low power physics tests.
The potential reactivity insertion due to the moderator pressure coefficient (2) that could result from depressurizing the coolant from 2100 psia to saturation pressure of 900 psia is approximately 0.1%2k/k.
During physics tests, special operating precautions will be taken.
In addition, the strong negative Doppler coefficient (1) and the small integrated ok/k would limit the magnitude of a power excursion resulting from a reduction of moderator density.
The requirement that the reactor is not to be made critical below DTT + 10 F provides increased assurances that the proper relationship between primary coolant pressure and temperatures will be maintained relative to the NDTT of the primary coolant system.
Heatup to this te=perature will be accomplished by operating the reactor coolant pumps.
If the shutdown margin required by Specification 3.5.2 is =aintained, there is no possibility of an accidental criticality as a result of a decrease of coolant pressure.
a,811aw 75-3 3.1-8
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The requirement for pressurizer bubble formation and specified water level when the reactor is less than 1% suberitical will assure that the reactor coolant system cannot bgcome solid in the event of a rod withdrawal accident of a start-up accident.43)
The requirement that the safety rod groups be fully withdrawn before criti-cality ensures shutdown capability during startup.
This does not prohibit rod latch confirmation, i.e., withdrawal by group to a maximum of 3 inches withdrawn of all seven groups prior to safety rod withdrawal.
The requirement for regulating rods being within their rod position limits ensures that the shutdown margin and ejected rod criteria at hot zero nower are not violated.
REFERENCES (1)
FSAR, Section 3 (2) FSAR, Section 3.2.2.1.4 (3) FSAR, Supplement 3, Answer 14.4.1 t
a 3.1-9
m
)
g.
If within one (1) hour of determination of an inoperable rod, it is not determined that a 1%Ak/k hot shutdown margin exists I
combining the worth of the inoperable rod with each of the other rods, the reactor shall be brought to the hot standby condition until this margin is established.
h.
Following the determination of an inoperable rod, all rods shall be exercised within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and ex'ercised weekly until 'the rod problem is solved.
1.
If a control rod in the regulating or safety rod groups is declared inoperable, power shall be reduced to 60 percent of the thermal power illowable for the reactor coolant pump com-bination.
j.
If a control rod in the regulating or axial power shaping groups is declared inoperable, operation above 60 percent of rated power may continue provided the rods in the group are positioned such that the rod that was declared inoperable is maintained within allowable group average position limits of Specification 3.5.2.2.a and the withdrawal limits of Specification 3.5.2.5.c.
3.5.2.3 The worths of single inserted control rods during criticality are limited by the restrictions of Specification 3.1.3.5 and the
, control rod position imits defined in Specification 3.5.2.5.
3.5.2.4 Quadrant Power Tilt a.
Whenever the quadrant power tilt exceeds 4 percent, except for physics tests, the quadrant tilt shall be reduced to less than 4 percent within two hours cr the following actions shall be taken:
(1) If four reactor coolant pumps are in operation, the allowable thermal power shall be reduced by 2 percent of full power for each I percent tilt in excess of 4 percent below the power j
level cutoff (see Figures 3.5.2-1A1, 3.5.2-1B1, 3.5.2-1B2, 3.5.2-1B3, 3.5.2-1C1, 3.5.2-1C2, and 3.5.2-1C3).
(2) If less than four reactor coolant pumps are in operation, the allowable thermal power shall be reduced by 2 percent of full power for each I percent tilt below the power allowable for the reactor coolant pump combination as defined by Specification 2.3.
(3) Except as provided in 3.5.2.4.b, the reactor shall be brought to the hot shutdown condition within four hours if the quadrant tilt is not reduced to less than 4 percent after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
- b. If the quadrant tilt exceeds 4 percent and there is simultaneous indication of a misaligned control rod per Specification 3.5.2.2, reactor operation may centinue provided power is reduced to 60 percent of the thermal power allowable for the reactor coolant 3.5-7
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pump combination.
c.
Except for physics tests, if quadrant tilt exceeds 9 percent, a controlled shutdown shall be initiated Lamediately and the reactor shall be brought to the hot shutdown condition within four hours.
i d.
Whenever the reactor is brought to hot shutdown pursuant to 3.5.2.4.a(3) or 3.5.2.4.c above, subsequent reactor operation is permitted for the purpose of measurement, testing, and corrective action provided the thermal power and the power range high flux setpoint allowable for the reactor coolant pump combination are restricted by a reduction of 2 percent of full power for each 1 per-cent tilt for the maximum tilt observed prior to shutdown.
e.
Quadrant power tilt shall be monitored on a minimum frequency of once every two hours during power operation above 15 percent of rated power.
3.5.2.5 Control Rod Positions a.
Technical Specification 3.1.3.5 does not prohibit the exercising of individual safety rods as required by Table 4.1-2 or apply to inoperable safety rod limits in Technical Specification 3.5.2.2.
b.
Operating rod group overlap shall be 25% t 5% between two sequential groups, except for physics tests.
c.
Except for physics tests or exercising control rods, the control rod with-drawal limits
- are specified on Figures 3.5.2-1A1 (Unit 1),
3.5.2-1B1, 3.5.2-1B2 and 3.5.2-1B3 (Unit 2',
and 3.5.2-1C1, 3.5.2-1C2, and 3.5.2-1C3 (Unit 3) for four pump operation and on Figures 3.5.2-2A (Unit 1), 3.5.2-2B (Unit 2), and 3.5.2-2C (Unit 3) for three or two pump operation.
If the control rod position limits are exceeded, corrective measures shall be taken immediately to achieve an acceptable control rod position.
Acceptable control rod positions shall then be attained within two hours.
- d. Except for physics tests, power shall not be increased above the power level cutoff as shown on Figures 3.5.2-1A1 (Unit 1) (see additional operating restrictions for Unit 1]* 3.5.2-1B1, 3.5.2-1B2, and 3.5.2-1B3 (Unit 2), and
- 3. 5. 2-1C1, 3. 5. 2-1C2, 3. 5. 2-1C3 (Unit 3), unless the following requirements are met.
(1) The xenon reactivity shall be within 10 percent of the value for operation at steady-state rated power.
(2) The xenon reactivitv shall be asymptotically approaching the value for operation at steady-state rated power.
3.5-8
I Bases i
The power-imbalance envelope defined in Figures 3.5.2-3A, 3.5.2-3B, and 3.5.2-3C is based on LOCA analyses which have defined the maximum linear heat rate (see Figure 3.5.2-4) such that the maximum clad temperature will not exceed the Final Acceptance Criteria.
Corrective measures will be taken immediately should the indicated quadrant tilt, rod position, or imbalance be outside their specified boundary.
Operation in a situation that would cause the Final acceptance criteria to be approached should a LOCA occur is highly improbable because all of the power distribution parameters (quadrant tilt, rod position, and imbalance) must be at their limits while simultaneously all other engineering and uncertainty factors are also at their limits.**
Conservatism is introduced by application of:
a.
Nuclear uncertainty factors b.
Thermal calibration c.
Fuel densification effects d.
Hot rod manufactur2ng tolerance factors The 25% + 5% overlap between successive control rod groups is allowed since the worth of a rod is lower at the upper and lower part of the stroke.
Control rods are arranged in groups or banks defined as follows:
Group Function 1
Safety 2
Safety 3
Safety 4
Safety 5
Regulating 6
Regul& ting 7
APSR (axial power shaping bank)
The rod position limits are based on the most limiting of the following three criteria:
ECCS power peaking, shutdown margin, and potential ejected rod worth.
Therefore, compliance with the ECCS power peaking criterion is ensured by the rod position limits.
The minimum available rod worth, consistant with the rod position limits, provides for achieving hot shut-down by reactor trip at any time, assuming the highest worth control rod that is withdrawn remains in the full out position (1).
The rod position limits also ensure that inserted rod groups will not contain single rod worths greater than 0.5% ak/k (unit 1) or 0.65% a k/k (units 2 and 3) at rated power.
These values have been shown to be safe by the safety analysis (2,3,4) of the hypothetical rod ejection accident. A maximum single inserted control rod worth of 1.0% ak/k is allowed by the rod positions limits at hot zero power.
A single inserted control rod worth of 1.0% Sk/k at beginning-of-life, hot zero power would result in a lower transient peak thermal power and, therefore, less severe environmental con-sequences than a 0.5% a k/k (unit 1) or 0.65% ak/k (units 2 and 3) ejected rod worth at rated power.
Control rod groups are withdrawn in sequence beginning with Group 1.
Groups 5,6, and 7 are overlapped 25 percent.
The normal position at power is for Groups 6 and 7 to be partially inserted.
- Actual operating limits depend on whether or not incore or excore detectors are used and their respective instrument and calibration errors.
The method used to define the operating limits is defined in plant operating procedures.
3.5-10
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The quadrant power tilt limits set forth in Specifice 'm. 3.5.2.4 have been established within the thermal analysis design base
- ing the definition of quadrant power tilt given in Technical Specificati.ua, Section 1.6.
These limits in conjunction with the control rod pos'. loa liaits in Specification 3.5.2.5c ensure that design peak heat rate cr.eeria are not exceeded during normal operation when including the effect. of potential fuel densification.
The quadrant tilt and axial imbalance monitoring in Specifications 3.5.2.4 and 3.5.2.6, respectively, normally will be performed in the process computer.
The two-hour frequency for monitoring these quantities will provide adequate surveillance when the computer is out of service.
Allowance is provided for withdrawal limits and reactor power imbalance limits to be exceeded for a period of two hours without specification violation.
Acceptance rod positions and imbalance must be achieved within the two-hour time period or appropriate action such as a reduction of power taken.
Operating restrictions are included in Technical Specification 3.5.2.5d to prevent excessive power peaking by transient xenon.
The xenon reactivity must be beyond the "undershoot" region and asymptotically approaching its equilibrium value at rated power.
REFERENCES 1 FSAR Section 3.2.2.1.2 2 FSAR Section 14.2.2.2 3FSAR SUPPLEMENT 9 4B&W FUEL DENSIF '.ATION REPORT BAW-1409 (UNIT 1)
BAW-1396 (UNIT 2)
BAW-1400 (UNIT 3) 3.5-11
)
1.
ROD INDEX 15 THE PERCENTAGE SUM OF THE WITHDRAWAL OF THE 2.
RESTRICTIONS ON VITHDRAWAL (HASHED AREAS) ARE N00lFIED AFTER THE. CONTROL ROD INTERCHANGE (SEE FIGURE 3 5.2-182)
(l25,102)
(l94,102)
(242,102)
_- 102 RESTRICTED REGION 80 - 82.5 (182.9,82.5)
(262.7,82.5)
POWER LEVEL CUTOFF A[
{
60 w
C Ug PERMISflBLE Y
OPERAiiNb a
40 REGION a?
5 g
20 l
O l
l I
I I
I I
I I
I I
I O
50 10 0 15 0 200 250 300 Red indes */. Withdrawal O
25 50 75 10 0 I
I 1
l 1
Group 7 0
25 50 75 10 0 l
I I
i I
Grap 6 CONTROL ROD GROUP WITHDRAWAL LIMITS Q
25 50 75 10 0 FOR 4 PUMP OPERATION UNIT 2 I
I I
I I
Grap 5 UNIT 2 i t OCONEE NUCLEAR STATION 3 5-14 Figure 3.5.2-181
.o m
l.
ROD INDEX is THE PERCENTAGE SUM OF THE WITHDRAWAL OF THE OPERATING GROUPS.
2.
THE ADDITIONAL RESTRICTIONS ON WITH0RAWAL (HASHED AREAS) APE IN EFFECT AFTER THE CONTROL R00 INTERCHANGE. THE RESTRICTIONS ON WITHDRAWAL ARE FURTHER MODIFIED AFTER 435 FULL POWER DAYS OF OPERATION (SEE FIGURE 3 5.2-183) 1 (194,102)
(242,102) 100 r
(172.4,82.5) l
- 82.5
/
(300,82.5) 80 (182.9,82.5)
(262.7,82.5)
~
POWER LEVEL h
RESTRICTED CUTOFF E
REGION O 60 ti a:
(162,50)
J 5 40 E
PERMISSIBLE OPERATING REGION 20 (121.15)
(119.5,0)
O I
I I
i l
l l
l l
l l
1 0
50 10 0 15 0 200 250 300 Rod index, % Withdrawd O
25 50 75 100 l
l I
f I
Group 7 0
25 50 75 K)O I
I l
l l
Groe 6 CONTROL ROD GROUP WITHDRAWAL LIMITS 0
25 30 75 10 0 I
I I
I FOR 4 PUMP OPERATION UNIT 2 Gran* 5 UNIT 2 OCONEE NUCLEAR STATION bu ao, e l
N N Figure 3.5.2-122 3.5-14a
r n
I 1.
ROD INDEX 15 THE PERCENTAGE SUM OF 1AE WITHDRAWAL OF THE OPERATING GROUPS.
2.
THE ADDITIONAL RESTRICTIONS ON W'THORAWAL ARE IN EFFECT AFTER 435 FULL POWER DAYS OF OPERATION.
(291.4, (270,102) 102)
_. 102 100
~
(172.4,82.5)
- 82.5 (300,82.5)
~
80 (244.5,82.5)
POWER LEVEL CUTOFF RESTRICTED REGION PERMISSIBLE h
~
OPERATING REGION y
(162,50) 2 E
40 e
E 20 (121,15)
{ (119.5,0)
~
I I
I I
I I
I I
I I
O O
50 10 0 15 0 200 250 300 Rod index, % Withdrawal O
25 50 75 10 0 l
i I
I I
Group 7 0
25 50 75 10 0 l
l I
l l
Group 6 0
25 50 75 10 0 CONTROL ROD GROUP WITHDRAWAL LIM.'TS I
I i
i t
FOR 4 PUMP OPERATION UNIT 2 Group 5 UNIT 2
[w Figure 3 5 2-1B3 OCONEE NUCLEAR STATION 3.5-15
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enn 1.
ROD INDEX 15 THE PERCENTAGE SUM OF THE WITHDRAWAL OF THE OPERATING GROUPS.
2.
RESTRICTIONS ON WITHDRAWAL (HASHED AREAS) ARE MODIFIED AFTER THE CONTROL R00 INTERCHANGE (SEE FIGURE 3.5.2-IC2) 102 RESTRICTED REGION 80 82.5
/
(182.9,82.5)
(262.7,82.5)
POWER LEVEL CUTOFF 5
1 2
o 60 f
Y l
5 PERMISSIBLE
~
d OPERATING y
40 Y
REGION 2
20 O
I I
I l
i I
l l
I I
I O
50 10 0 15 0 200 250 300 Rod Index, % Withdrowol 0
25 50 75 10 0 l
i I
I i
Group 7 0
25 50 75 10 0 I
l I
I Grow 6 CONTROL R00 GROUP WITHDRAWAL LIMITS 0
25 50 75 10 0 FOR 4 PUMP OPERATl0tl UNIT 3 1
I I
I I
Group 5 UNIT 3 lmt OCONEE NUCLEAR STATION 3.5-16 Figure 3.5.2-1c1
e.
2.
)
1.
ROD INDEX 15 THE PERCCNTAGE SUM OF THE WITH0RAWAL OF THE OPERATING GROUPS.
2.
THE ADDITIONAL RESTRICTIONS ON WITHDRAWAL (HASHED AREAS) ARE IN EFFECT AFTER THE CONTROL ROD INTERCHANGE. THE RESTRICTIONS ON WITH0RAWAL ARE FURTHER tSDIFIED AFTER 435 FULL POWER DAYS OF OPERATICN (SEE FIGURE 3 5.2-IC3)
(194,102)
(242,102) 100 (172,4,82,5) 1
/
- 825 (182,9,82.5)
(300,82.5) 80 (262,7,82,5)
RESTRICTED POWER LEVEL
~~
REC 10N CUT 0FF ac g
60 n.
w
'(162,50) j o
40 a:
l y
PERMISSIBLE OPERATING 20 REGION (121.15) i (119 5,0) 0 l
i I
I I
I I
I I
I l
0 50 10 0 15 0 200 250 300 Rod inder,
- /o Withdrawai 0
25 50 75 10 0 l
I I
I l
Group O
25 50 75 10 0 l
l l
l I
Group 6 CONTROL ROD WITHDP.AWAL LI 0
25 50 75 loo I
FOR h PUMP OPERATION UNIT 3 Grog 5 UNIT 3 lsuu rom OCONEE NUCLEAR STATION Figure 3.5.2-Ic2 3.5-16a
O e
)
1.
R0D INDEX 15 THE PERCENTAGE SUM OF THE WITHu.AWAL 0F THE OPERATING GROUPS.
2.
THE ADDITIONAL r.ESTRICTIONS ON WITHDRAWAL ARE IN EFFECT AFTER 435 FULL DAYS POWER OF OPERATION.
(29],4, (270,102) 102)
-- 102
,g
~
(172.4,82.5)
- 82.5 (300,82.5) 80 (244.5,82.5)
POWER LEVEL CUTOFF RESTRICTED
~'
REGION P MISSIBLE
.- 60 j
OPERATING REGION (162.50) g 2
b 4C ' -
~
~
e 5
s2 zo (121.15)
{ (119.5,0) l l
l l
I l
0 I
I I
l 0
50 10 0 ISO 200 250 300 Rod Inien, % Withdrawal O
25 50 75 10 0 l
I I
I I
Group 7
0 25 50 75 10 0 l
I I
I I
Group 6 0
25 50 75 10 0 I
i i
I I
Gerv 5 CONTROL ROD GROUP WITHDRAWAL LIMITS FOR 4 PUMP OPERATION UNIT 3
)
UNIT 3 locu rowie, OCONEE NUCLEAR STATION Y
Figure 3.5.2-Ic3 3.5-17
'3
)
l.
R0D INDEX 15 THE PERCENTAGE SUM OF THE WITHDRAWAL OF THE OPERATING GROUPS.
(177.4,102)
- 102 10 0 E
so PERMISSIBLE i
"ESTRICTED REGION OPERATING REGION u
I f
60
?
[o (162,50)
Ml 40 g
oo 20 ug (121.15)
(119.5.0)
O 1
I I
I I
I I
I I
l O'
50 10 0 15 0 200 250 300 Rod index, */. Withdrawol 0
25 50 75 10 0 I
I I
I I
Group 7 0
25 50 75 10 0 l
l I
I I
Group 6 0
25 50 75 30 0 st4 TROL R0D GROUP WITHDRAWAL LIMITS l
I I
I I
l FOR 3 AND 2 PUMP OPERATION UNIT 2 G
5 UNIT 2 OCONEE NUCLEAR STATION Figure 3.5.2-2B 3.5-19
O
..)
6 1.
ROD INDEX 15 THE PERCENTAGE SUM OF THE WITHDRAWAL OF THE OPERATING GROUPS.
102 (177,4,102) 00 RESTRIGTED PERMISSIBLE r
3 REGION OPERATING Q
80 REGION 5
E 8
E 60 sa:
5 4
(162,50)
M E
j 40 A
b 20 (121,15) h (l19.5,0)
O I
l l
I l
l l
I l
i O
50 10 0 15 0 200 250 300 Rod index, % Withdrowol O
25 50 75 10 0 1
I I
I I
Group 7 0
25 50 75 10 0 I
I I
I I
Group 6 ceNTROL ROD GROUP WITHDRAWAL LIMITS 0
25 50 75 10 0 FOR 3 AND 2 PUMP OPERATION UNIT 3 Grae 5 UNIT 3
' sani m OCONEE NUCLEAR STATION s
Figure 3.5.2-2C 3 5-20