ML19317G915
| ML19317G915 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/08/1975 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML19317G907 | List: |
| References | |
| NUDOCS 8004020572 | |
| Download: ML19317G915 (12) | |
Text
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RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS 9
Limiting Conditions for Operation 3.1.7 MODERATOR TEMPERATURE COEFFICIENT OF REACTIVITY Specification The moderator temperature coefficient shall not be positive at power levels cbove 95 percent of rated power.
Bases A non-positive moderator ccefficient at power levels above 95 percent of rated power is specified such that the maximum clad temperatures will not exceed the Final Acceptance Criteria based on LOCA analyses.
Below 95 parcent of rated power the Final Acceptance Criteria will not be exceeded 36 with a positive moderator temperature coefficient of +0.9 x 10-4 Ak/k/F corrected to 95 percent of rated power. All other accident analyses as raported in the FSAR have been performed for a range of coderator temperature 4
coefficients including +0.9 x 10-4 Ak/k/F.
The experimental value of the moderator coefficient will be corrected to obtain the hot full power moderator coefficient.
When the hot zero-power value,is corrected to obtain the 95 percent power value, the following corrections will be applied:
1.
Uncertainty in isothermal measurement - The measured moderator temperature coefficient will contain uncertainty owing to the AT of the base and perturbed conditions and the uncertainty in the reactivity measurement.
Proper corrections will be added for these conditions to provide a conservative moderator coefficient.
2.
Doppler contribution at hot zero power - During measurement.of the isotherral moderator coefficient at hot zero power, the fuel tem-perature will increase by the same amount as the moderator.
The measured temperature coefficient must therefore be increased to obtain a pure moderator temperature coefficient.
~
3.
Moderator temperature change - The hot zero-power measurement must be corrected for the difference in water temperature at zero power (532 F) and 15 percent power (38? F).
Above this power, the average moder,ator temperature remains 582 F.
4.
Fuel temperature interaction (power effect) - The moderator coef-ficient must be -adjusted to account for the interaction of an average moderator temperature with increasing fuel temperatures 3-15 8004020 b b
T RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Limiting Conditions for Operation F.
If a control rod in the regulating or axial power shaping groups is declared inoperable per Specification 4.7.1.2, oper-ation above 60% 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 posi-tion limits of Specification 4.7.1.2 and the withdrawal limits of Specification 3.5.2.5.c.
3.5.2.3 The worth of a single inserted control rod shall not exceed 0.65 per-cent ak/k at rated power or 1.0 percent Ak/k at hot zero power except for physics testing when the requirement of Specification 3.1.8 shall apply.
3.5.2.4 Quadrant 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 or 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 maximum allowable power for each 1 percent tilt in excess of 92 percent maximum allowable power.
Maximum allowable l36 power is defined in Technical Specification.
(2)
If less than four reactor coolant pumps are in operation, the allowable thermal power shall be reduced by 2 percent of maximum allowable power for each 1 percent tilt below the power allowable for the reactor coolant pump com-bination.
(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 cent after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
reduced to less than 4 per-(4)
The power range high flux set point shall be reduced 2 percent of the maximum allowable flux for the RC pump combination for each 1 percent tilt in excess of 4 percent.
B.
If the quadrant tilt exceeds 4 percent and there is simulta-neous indication of a misaligned control rc ' per Specification 3.5.2.2, reactor operation may continue, provided power is reduced to 60 percent of the thermal power allowable for the reactor coolant pump combination.
C.
Except for physics tests,1f quadrant the reactor shall be brought tilt exceeds 9 percent, within four hours.
to the hot shutdown condition 3-32
RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Limiting Conditions for Operation D.
Whenever the reactor is brought to hot shutdown pursuant to 3.5.2.4a(3) or 3.5.2.4c above, subsequent reactor operation is permitted for the purpose of measurement, testing and correc-tive action provided the. thermal power and the power range high flux setpoint allowabic for the reactor coolant pump combina-tion are restricted by a reduction of 2 percent of maximum allowable power for each 1 percent tilt.
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 (safety rod withdrawal) 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 Specif,1 cation 3.5.2.2.
B.
Operating rod group overlap shall be 25 percent 5 percent between two sequential groups, except for physics tests.
C.
Except for physics test or exercising control rods, the con-trol rod withdrawal limits are specified on Figure 3.5.2-1.
If 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 test, power shall not be increased above the power level cut-off of 92 percent of the maximum allowable l36 power level unless one of the following conditions is satis-fled:
(1)
Xenon reactivity is within 10 percent of the equiliabrium value for operation at the maximum allowable power level and asymptotically approaching stability.
(2)
Except for xenon free start-up, when 3.5.2.5D(1) applies, the reactor has operated within a range of 87 to 92 per-l36 cent of the maximum allowable power for a period exceed-ing 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> in the soluble poison control mode.
3.5.2.6 Reactor power imbalance shall be monitored on a frequency not to exceed two hours during power opeation above 40 percent rated power. Except for physics test, imbalance shall be maintained within the envelope defined by Figure 3.5.2-2.
If the imbalance is not within the envelope defined by Figure 3.5.2-2, corrective measures shall be taken to achieve an acceptable imbalance.
If an acceptable imbalance is not achieved within two hours, reactor power shall be reduced until imbalance limits are set.
3-33
RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Limiting Conditions for Operation.
3.5.2.7 The control rod drive patch panels shall be locked at all times with limited access to be authorized by the superintendent.
Bases The power-imbalance envelope defined in Figure 3.5.2-2 is based on LOCA analyses which have defined the anximum linear heat rate (see Figura 3.5.2-3) such that the maximum clad temperature will not exceed the Final Acceptance Criteria. Operation outside of the power imbalance envelope alone does not 36 constitute a situation that would cause the Final Acceptance Criteria to be exceeded should a LOCA occur. The power imbalance envelope represents the boundary of operation limited by the Final Acceptance Criteria only if the control rods are at the position limits as defined by Figure 3.5.2-1 and if a 4 percent quadrant power tilt exists. Additional conservatism is introduced by application of:
A.
Nuclear uncertainty factors.
B.
The,rmal calibration uncertainty.
C.
Fuel densification effects.
D.
Hot rod manufacturing tolerance factors.
The 30 percent 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
Regulating 7
Regulating 8
APSR (axial power shaping bank)
Control rod groups are withdrawn in sequence beginning with Group 1.
Group 5 is overlapped 25 percent with Groups 6 and 7, which operate in parallel.
The normal position at power is for Groups 6 and 7 to be partially inserted.
The minimum available rod worth provides for achieving hot shutdown by reactor trip at any time assuming the highest worth control rod remains in the full
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out position.ll)
Inserted rod groups during power operation will not contain single rod worths greater than 0.65 percent ak/k.
This value has been shown to be safe by the safety analysis of the hypothetical rod ejection accident.(2) A single inserted control rod worth of 1.0 percent ak/k at beginning of life, hot, zero power would result in the same transient peak thermal power and therefore the same environmental consequences as a 0.65 percent Ak/k ejected rod worth at ra.ted power.
l 3-33a
RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Limiting Conditions for Operation The quadrant power tilt limits set forth in Specification 3.5.2.4 have been established within the thermal analysis design base using the definition of quadrant power tilt given in Technical Specifications, Section 1.6.
These limits in conjunction with the control rod position limits in Specification 3.5.2.5c ensure that design peak heat rate criteria are not exceeded during normal operation when including the effects of potential fuel densification.
The quadrant tilt and axial imbalance monitoring in Sepcifications 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 viola tion. Acceptance rod positions and imbalance must be achieved within the two-hour ttne period or appropriate action such as a reduction of power taken.
Operating restrictions are included in Technical Specifications 3.5.2.5d(1) and 3.5.2.5d(2) to prevent excessive power peaking by transient xenon. The xenon reactivity must either be beyond the "undershoot" region and asympto-tically approaching its equilibrium value at rated power or the reactor must be operated in the range of 87% to 92% of the maximum allowable power for a l36 period exceeding two hours in the soluabic poison control mode so that the transient peak is burned out at a lower power level.
During physics testing, additional safety margins are provided by administra-tively setting special reactor protection system limitations. During the power ascension testing program, the following high flux trip settings will be set prior to increasing power to the next plateau:
Test Plateau Level %
Overpower Trip %
0
<5 15 50 40 50,
75 95 90 100 l
100 1
05.5 REFERENCES
(1) FSAR, Paragraph 3.2.2.1.2 (2) FSAR, Paragraph 14.2.2.4 3-33b
200,102 100 182.4.102 <p 90 POWER' LEVEL 180.2.92I CUT 0FF 174.1,82 80 70 RESTRICTED REGION 60 5
g 50 A
122.3,43 PERMISSIBLE 40
-0PERATING' E
REGION e
30 20 80,85 10 49.o 0
I I
I I
I l'
I I
O 20 40 60 80 100 120 140 160 180 200 Rod Index. "s Withdrawn 0
25 50 75 100 I
I I
I I
O 25 50 75 100 Group 6 & 7 I
i l
I I
Group 5
- 1. Rod index is the. percentage sum of the withdrawal of control rod groups 5,6 and 7.
- 2. The restrictions on rod position are in effect after 100 EFPD.
Proposed Change No. 36 ROD POSITION LIMITS July 9,1975 -
Figure 3.5.2-1
120 g
RESTRICTED REGION 110
-15.3,102
+10.2,102 100
^
O hi+11.0,92
-15.6.92 90
-23.0.82 613.6,80 g
PERhllSSIBLE b
70 OPERATING
{
RANGE i
E 60 I
o h
50 e
p34.u.3 40 f,*'9'8'**
30 20 10 0
i i
i i
i i
-60
-40
-20 0
+20
+40
+60 Core imbalance, 5
- 1. The limits are in effect after 100 EFPD.
OPERATIONAL POWER IMBALANCE ENVELOPE Pruposed Change No. 36 July 9, 1975 Figure 3 5 2-2
i i
I 21 20
- 19 i
s M
18
=
17
/
I f
\\
16 f
g 15 j
- c 14 j
13 12 0
2 4
6 8
10 12 Axial Location of Peak Power From Bottom of Core. f t LOCA LIMITED MAXIMUM ALLOWABLE LINEAR HEAT RATE Figure 3.5.2-3 Proposed Change No. 36 July 9,1975
ATTACHMENT 2 NORMAL SINGLE SYSTEM DESCRIPTION
_ POSITION FAILURE EVALUATION HPI Seal injection line RB SF signal-Opens Would cause slight increase of'HPI pump flow (Figure 9.2-1
' isolation valve to close rate in associated HPI string. No effect on s
Isolation valve in H2 Close Opens Could add H2 to makeup tank and increase additiet line to make-makeup tank pressure to the setpoint of the up tank H2 regulator. No effect on either HPI string as makeup. tank outlet valve is closed by SF signal.
Isolation valve in Closed Opens Would vent off the gas pressure from the makeup tank vent line makeup tank.
Even if this failure occurred at the same time as initiation of the HPI system, it would not cause a ~ loss of suction to the connected HPI string. This failure would not vent the pressure off before the BWST would be supplying suction to that HPI pump.
The BWST 16" outlet valve has a 14 second cycle time for full stroke and would be open sufficiently in 2 seconds or less to provide suction flow to that HPI pump which-takes 3.5 seconds to reach full speed. No effect on other HPI string.
Isolation valve in SF signal Opens Minor effect on one HPI string only. Would normal makeup line to close which connects to one cause some increase in flow rate by that HPI string as it has opened up a line in HPI line of HPI string parallel with a portion of the HP injection "A"
path.
Flow rate could be reduced, if re-quired, by: (1) closing Valve MU-V17 (fails closed on loss of air) which is in series with Valve MU-V18, or (2) throttling or closing one or both of HP injection Valves MU-V16A and MU-168.
Page 1 of 3
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NORMAL SINGLE SYSTEM DESCRIPTION POSITIGN FAILURE EVALUATION HPI Isolation valve in SF signal Opens Any effect is only on one HPI string.
If makeup tank outlet to close makeup tank initial pressure is sufficiently line high enough, the hydrogen could push the water out of the tank resulting in the gas s
reaching one HPI pump and causing a reduction in pump head or gas binding of the pump when the BWST is at a reduced ware, level. There would be no effect on the ' /I string which r
is not connected to the makeup tank outlet line.
LPI DH drop line (from Closed Opens No effect on LPI capability.
(Figure 9.5-1 hot leg) isolation of FSAR) valve RB sump outlet Closed Opens At most, this could affect one LPI pump and valve one RB spray pump associated with that ECCS string. This would not affect either HPI string. A RB pressure above =30 psig would prevent flow out of the BWST to that LPI pump and RB spray pump when the BWST is full.
These pumps could be up to full spged within
=5 seconds af ter t1e LOCA. A 5 f t' LOCA will release =2 times t1e sump volume (in liquid for) within the first 5 seconds.
The LPI pump and spray pump probably are capable of operating dry for several minutes without incurring damage which would cause a loss of function.
This single failure would have no effect on the two HPI strings or on the other LPI or building spray strings.
Isolation valve in Closed Opens Would increase flow rate of the connected crossover line from LPI pump, possible causing cavitation, as LPI discharge line LPI pump would be pumping to the reactor to HPI pump suction vessel and also to the suction of one HPI pump. But other LPI string is not affected.
LPI line flow con-Open (also Closes Stops flow in that LPI string but other LPI trol valve SF signal to string is not affected. Handwheel on open) operator could be used to open valve.
Page 2 of 3
NORMAL SINGLE SYSTEM DESCRIPTION POSITION FAILURE EVALUATION i.
LPI cooler bypass line Closed Opens Would reduce heat removal rate of that LPI flow control valve cooler but other LPI string is not affected.
Isolation valves in Closed Opens No effect on LPI capability.
cross-connect line s
(Figure 6.2-1 CF tank discharge line Open Not Tech. Spec. 3.3.1 requires breaker for valve of FSAR) isolatien valve credible operator to be locked open.
CF tank drain line Closed Opens No effect as there is a normally closed isolation valve manual valve located in series with the motor operated valve. Manual valve is the outside building isolation valve.
CF tank vent line Closed Not The next proposed change to the Technical isolation valve credible Specifications will require this valve to be closed and the breaker for this valve operator to be locked open. Therefore, there can be no loss of pressure and subsequent lowered discharge flow rate.
CF tank makeup line Closed Opens-No-effect as tnere is a normally closed isolation valve valve in the line located outside of the RB.
Page 3 of 3
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ATTACHMENT'3 A comparison'of Key Parameters Employed in the B&W Generic ECCS Evaluation Model to Rancho Seco Unit No.1 Parameters Parameter Generic Model SMUD Margin (a) 6
- 1. 98x106
+0.23x106 3
2.205x10 Reactor Building Free Volume, ft Reactor Building Walls with Steel liner Plate Heat Sink Area, ft2 67,410 57,800
+9,610 Paint Thickness, ft 0.00083 0.0005
-0.00033 Steel Thickness, ft 0.05215 0.5215 Concrete Thickness, ft 4.0
- 4. 0 Reactor Building Dome with Steel Liner Plate 2
18,375 22,500
-4,125 Heat Sink Area, ft Paint Thickness, ft 0.00083 0.0005
-0.00033 Steel Thickness, ft 0.06667 0.06667 Cencrete Thickness, ft 3.0 3.5
-0.5 Painted Internal Steel Heat Sink Area, ft2 285,000 187,364
+97,636 Paint Thickness, ft 0.00083 0.00075
-0.00008 Steel Thickness, ft 0.03125 0.03125 Internal Stainless Steel Heat Sink Area, ft2 10,000 16,500
-6,500 Thickness, ft 0.03125 0.03125 Internal Concrete Heat Sink Area, ft -
160,000 229,000
-69,000 2
Paint Thickness,ft 0.00083 0.00069
-0.00014 Concrete Thickness, ft 1.0 1.0 (a)+ indicates more conservative values than contained in the generic model.
NOTE:
L.