ML20206B076
| ML20206B076 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 04/06/1999 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML20206B074 | List: |
| References | |
| NUDOCS 9904290134 | |
| Download: ML20206B076 (12) | |
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1 Attachment 1 Marked Copy of the Technical Specification l
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9904290134 990406 PDR ADOCK 05000369 P pg
RTS Instrumentation 3.3.1
,* Tabla 3.3.1 1 (paga 3 of 7)
Reactor Tnp System instrumentation
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APPLICABLE MODES OR -
OTHER I. SPECIFIED REQUIRED SURVEILLANCE ALLOWABLE TRIP i
,'~ FUNCTION CONDmONS CHANNELS CONDmONS REQUIREMENTS VALUE SETPOINT I
- 12. Underfrequency 1(f) 1 per bus M SR 3.3.1.9 a 55.9 Hz a 56.4 Hz RCPs SR 3.3.1.10 SR 3.3.1.16
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- 13. Steam Generator 1,2 4 per SG E SR 3.3.1.1 a15% 2 6.7%
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(SG) Water Level. SR 3.3.1.7 Low Low SR 3.3.1.10 SR 3.3.1.16
- 14. Turtune Tnp
- 15. Safetyinjection(SI) 1,2 . 2 trains O SR 3.3.1.5 NA NA input from SR 3.3.1.14 Engineered Safety Feature Actuation System (ESFAS)
- 16. 3eactor Trip System interiocks y
- a. Intermediate 2(d) 2 S SR 3.31.11 g[E 11 amp 3 1E 10 Range Neutron SR 3.3.1.13 amp Flux, P-6
- b. Low Power 1 1 per train T SR 3.3.1.5 NA NA Reactor Trips Block, P-7
- c. Power Range 1 4 T SR 3.3.1.11
' 549% RTP s 48% RTP Neutron Flux, SR 3.3.1.13 PB 7
P-10 -RTP
- e. Turbine impJse 1 2 T SR 3.3.1.12 5 11% turtune s10%
Pressure, P-13 SR 3.3.1.13 impulse turbine pressure impulse equivalent pressure equivalent (continued)
I l (d) Below the P 6 (Intermediate Range Neutron Flux) intertocks.
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{ (f) Above the P 7 (Low Power Reactor Tnps Block) interto'.
f (g) Above the P 8 (Power Range' Neutron Flux) inter'Xk.
l MCGuire Units 1 and 2 3.3.1-16 Amendment NoS.104/1GG
Attachment 2 Proposed New Technical Specification
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. . RTS Instrumentation 3.3.1 Table 3.3.1 1 (page 3 of 7)
Reactor Tnp System Instrumentation APPLICABLE MODES OR OTHER SPECIFIED REQUIRED SURVEILLANCE ALLOWABLE TRIP FUNCTION CONDITIONS CHANNELS CONDITIONS REQUIREMENTS VALUE SETPOINT
- 12. Underfrequency 1(O 1 per bus M SR 3.3.1.9 RCPs a 55.9 H2 2 56.4 Hz SR 3.3.1.10 SR 3 3.1.16
- 13. Steam Generator 1,2 4 per SG E SR 3.3.1.1 (SG) Water Level- 2 15% 3 16.7 %
SR 3.3.1.7 Low Low SR 3.3.1.10 SR 3.3.1.16
- 14. Turbine Trip
- 15. Safetyinjection(SI) 1,2 2 trains O SR 3.3.1.5 NA Input from Engineered NA SR 3.3.1.14 ;
Safety Feature Actuation System l (ESFAS)
- 16. Reactor Tnp System Intertocks
- b. Low Power 1 1 per train T SR 3.3.1.5 NA NA Reactor Tnps Block, P.7
P-10 RTP
- e. Turbine Impulse 1 2 T SR 3.3.1.12 Pressure, P 13 s 11% turbine s10%
SR 3.3.1.13 impulse turbine w ssure impulse equivalent pressure equivalent (contir'ued)
(d) B310w the P 6 (Intermediate Range Neutron Flux) interlocks.
(f) Above the P 7 (Low Power Reactor Trips Block) interlock.
(g) Above the P-8 (Power Range Neutron Flux) interlock.
McGuire Units 1 and 2 3.3.1-16 Amendment NoS.
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U. S. Nuclear Regulatory Commission Attachment 3 April 6, 1999 Page 1 Description of the Proposed Changes:
McGuire Technical Specification Table 3.3.1-1 specifies an allowable value range of 3 9% RTP and 5 11% RTP and a trip setpoint value of 3 10% RTP for the Power Range (PR) Neutron Flux P-10 permissive.
McGuire Technical Specification Table 3.3.1-1 specifies an allowable value of 3 6E-ll amp and a trip setpoint value of 3'lE-10 amp for the Intermediate Range (IR) Neutron Flux P-6 permissive. j i
Westinghouse's " Precautions, Limitation and Setpoints" document !
prepared for McGuire Nuclear Station states that PR bistables should have loop width adjustment set to give a deadband of i approximately 2% RTP. This deadband is necessary to prevent the {
bistables from cycling due to the insignificant fluctuations in I neutron flux near the P-10 nominal setpoint value of 10% RTP. I This document also states that IR bistables should have loop width adjustment set to give a deadband of approximately 50% of the setpoint. This deadband is necessary to prevent the bistables from cycling due to the insignificant fluctuations in neutron flux near the P-6 nominal setpoint value.
The allowable value range for P-10 needs to be expanded to a range that would include at least a 2% RTP deadband between the trip and reset setpoints and some margin for instrument drift.
Table 3.3.1-1, Function 16d allowable value for the P-10 permissive is proposed to be changed from "> 9% RTP and < 11%
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RTP" to "3 7% RTP and 5 11% RTP" Changing the lower value to 7%
RTP is based on a nominal reset value of 8% RTP (which provides a 2% RTP deadband with the 10% RTP setpoint) with a + 0.025 VDC tolerance on the bistable reset value that equates to 1 0.3% RTP.
l This tolerance is based on Westinghouse specification of the bistable card trip setpoint stability of 0.25% of fu]l scale (0.0025 x 10.000 VDC = 0.025 VDC). Therefore by procedure, the lowest value that the reset value can be set at is 7.7% RTP.
'This value is rounded down to 7% RTP so that normal bistable drift will not place the bistable outside of the Technical Specification allowable value. Similarly, the maximum value that the procedure will set the P-10 trip setpoint at is 10.3% RTP with 0.7% RTP margin to accommodate normal bistable drift. The tolerance and margin for drift for P-10 permissive are consistent with those for other PR trip functions.
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. l U. S. Nuclear Regulatory Commission Attachment 3 April 6, 1999 Page 2 The allowable value for P-6 needs to be expanded to a value that would include at least a 50% of nominal setpoint deadband between the nominal trip and reset setpoints and some margin for instrument drift. Table 3.3.1-1, Function 16a allowable value for the P-6 permissive is proposed to be changed from "3 6E-ll amp" to "3 4 E-ll amp" . Changing the lower value to g 4E-11 amp is based on a nominal reset value of SE-ll amp (which provides a 50% of the lE-10 amp trip setpoint deadband) with a + 0.025 VDC tolerance on the bistable reset value. Therefore by procedure, the lowest value that the reset value can be set at is 4.73E-ll amp. This value is rounded down to 4E-ll amp so that normal bistable drift will not place the bistable outside of the Technical Specification allowable value. The tolerance and margin for drift for P-6 permissive are similar to those for P-10 permissive.
Technical Justification:
Background:
Nuclear Overpower Trips:
The power range high neutron flux trip circuit trips the reactor when two of the four power range channels exceed the trip setpoint. In each channel there are two independent bistables, each with its own trip setting used for a high and a low range trip setting. The high trip setting provides protection during normal power operation and the low trip setting provides protection during startup. The low trip setting can be manually j bypassed when two out of the four power range channels read above l the P-10 setpoint value and is automatically reinstated when three out of the four channels decrease below the P-10 reset value.
The intermediate range high neutron flux trip circuit trips the reactor when one out of the two intermediate range channels exceeds the trip setpoint. This trip, which provides protection during reactor startup, can be manually blocked if two out of four power range channels are above the P-10 setpoint. Three out of the four power range channels below the P-10 reset value automatically reinstates the intermediate range high neutron flux trip.
The source range high neutron flux trip circuit trips the reactor when one of the two source range channels exceeds the trip l setpoint. This trip, which provides protection during reactor l
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U. _ S . Nuclear. Regulatory Commission Attachment 3 April 6, 1999 Page 3 startup and unit shutdown, can be manually bypassed when one of the two intermediate range channels reads above the P-6 setpoint
, value and is automatically reinstated when both intermediate
-range channels decrease below the P-6 reset value. This trip is also automatically bypassed by two-out-of-four logic from the power range protection interlock P-10.
Power Escalation Permissives:
Continuation of startup operation or power increase requires a permissive signal'from the higher range instrumentation channels before the lower range level trips can be manually blocked by the operator.
A one-of-two intermediate range permissive signal P-6 is required prior to source range level trip blocking. A source range manual block is provided for each logic train and the blocks must be in i
effect on both trains in order to proceed in the intermediate '
range. Source range level trips are automa ically reactivated and high voltage restored when both interm< ate range channels are below the' permissive P-6 level. Sourc range high voltage is )
automatically cut off when power is above le permissive P-10 level in order to prevent detector damage.
The intermediate range level trip and the power range (low setpoint) trip can only be blocked after satisfactory operation and permissive information are obtained from two-of-four power range channels. The low setpoint power range trip and i intermediate range trip can be independently blocked. These {
trips are automatically reactivated when any three of the four power range channels are below the permissive P-10 level, thus ensuring automatic activation to more restrictive trip protection.
Justificdtion:
Changing the lower value of the P-10 permissive allowable values from 1 9% RTP to 3 7% RTP would allow for tripping and resetting of_the permissive at a. lower reactor power level. Having the backup capability to automatically de-energize the SR channels at a power level approaching 7% RTP increasing reactor thermal power is not.a nuclear safety concern since the LSR channels are normally manually blocked just above the IR P-6 permissive trip setpoint of 1E-10 amp, significantly below the 7%
RTP. On decreasing power, automatic re-energization of the SR ,
detectors (and unblocking of the SR reactor trip) would be )
unaffected because even at 7% RTP, the P-10 permissive would i
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.,l U. S. Nuclear Regulatory Commission Attachment 3 April 6, 1999 Page 4 reset well in advance of the P-6 permissive. Also, a review of the UFSAR Chapter 15 accident analyses determined that no credit is taken for the SR reactor trip.for any of the UFSAR accidents.
A review of the UFSAR Chapter 15 accident analyses determined that no credit is taken for the IR neutron flux-trip function for any of the UFSAR accidents. Therefore, blocking or enabling of this function.at a lower power level poses no nuclear safety concerns. A review of the UFSAR Chapter 15 accident analyses determined that credit is taken for the PR neutron flux low setpoint trip for a feedwater system malfunction causing an increase in feedwater flow accident (15.1.2), uncontrolled rod cluster control assembly bank withdrawal from a subcritical or low power startup condition accident (15.4.1), and spectrum of rod cluster control assembly ejection accidents (15.4.8). All three of these accident scenarios are bounded by cases at 0% RTP taking credit for the PR neutron flux low setpoint trip and cases at > 10% RTP'taking credit for the PR neutron flux high setpoint trip.
The uncontrolled rod cluster control assembly bank withdrawal from power accident (15.4.2) analyses are performed at initial power levels of 10%, 50%, and 100% RTP to demonstrate that acceptable results are obtained for a range of initial power levels. The PR neutron flux high setpoint trip, high pressurizer ,
pressure trip, overpower delta-T (OPDT) trip and overtemperature i delta-T (OTDT)-trip provide core protection. These analyses are I performed for a range of reactivity addition rates to ensure that the limiting cases are identified. The P-10 reset function at approximately 10% RTP was selected for the lower end of the range of initial power levels to be analyzed in Section 15.4.2 analysis. With the P-10 reset function changed to as low as 7%
RTP, the conclusions of Section 15.4.2 analysis would not change.
This is due to the similarity in the transient response regardless of the slight difference in the initial power level '
(7% vs 10%).
As shown by Figure 15-73 in the McGuire UFSAR, the minimum DNB condition for the uncontrolled bank withdrawal from 10% RTP occurs for withdrawal rates where the OTDT and the high pressurizer pressure reactor trips intersect. The OTDT and high ;
pressurizer pressure reactor trips are thermal trips. The margin j to trip for the OTDT trip is not significantly increased in <
starting the bank withdrawal event from 7% RTP versus 10% RTP. i The' margin to trip for the high pressurizer pressure trip is not ;
affected,.since the same initial reactor coolant system pressure I would be assumed in both cases, and thus the reactor is expected
U. S. Nuclear Regulatory Commission Attachment 3 April 6, 1999 Page 5 to trip at the same time. Since the uncontrolled bank withdrawal event is analyzed from both zero power and 10% RTP, all low power initial conditions are adequately bounded. The analyses of a range of reactivity addition rates provide a comprehensive set of analysis results for comparison to the acceptance criteria.
Based on the above discussion, changing the P-10 permissive lowest allowable value to 7% RTP is technically justified.
Lowering the P-6 permissive allowable value from 3 6E-ll amp to 3 4E-11 amp would allow the SR channels to be blocked at a lower increasing reactor power level and delay resetting of the permissive at a lower decreasing reactor power level. A review of the UFSAR Chapter 15 accident analyses determined that no credit is taken for the SR reactor trip for any of the UFSAR accidents. Therefore, there are no nuclear safety ramifications associated with this proposed change to the P-6 permissive.
McGuire procedures currently have the trip and reset setpoints for the P-10 permissive set at "10.5% RTP" and "9.5% RTP",
respectively. Likewise, the procedural trip and reset setpoints for the P-6 permissive are "lE-10 amp" and "7E-11 amp",
respectively.
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U. S. Nuclear Regulatory Commission Attachment 4 April 6, 1999 Page 1 No Significant Hazards Considerations As required by 10 CFR 50.91, this analysis is provided concerning whether the requested amendment involves significant hazards considerations, as defined by 10 CFR 50.92. An amendment' request involves no significant hazards considerations if operation of the facility in accordance with the requested amendment would not: 1)
Involve a significant increase in the probability or consequences of an accident previously evaluated; or 2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or 3) Involve a significant reduction in a margin of safety.
Criterion 1 - Would operation of the facility in accordance with the requested amendment involve a significant increase in the' probability or consequences of an accident previously evaluated?
The reactor protection interlocks are provided to ensure reactor trips are in the correct configuration for the current unit status. They back up operator actions to ensure protection system functions are not bypassed during unit conditions under which the safety analysis assumes the functions are not bypassed. The proposed changes involve changing the lower value of the P-10 permissive (power range (PR) neutron flux) allowable values from 3 9% RTP to 3 7% RTP, and changing the P-6 permissive (intermediate range (IR) neutron flux) allowable value from 3 6E-11 amp to 3 4E-11 amp. Changing the P-10 allowable value would allow for tripping and resetting of the permissive at a lower reactor power level. Changing the P-6 allowable value would allow the source range (SR) channels to be blocked at a lower increasing reactor power level and delay resetting of the permissive at a lower decreasing reactor power level.
A review of the UFSAR Chapter 15 accident analyses determined that no credit is taken for the SR reactor trip or the IR reactor trip for any of the UFSAR accidents. Credit is taken for the PR low setpoint trip for a feedwater system malfunction causing an increase in feedwater flow accident (15.1.2), uncontrolled rod cluster control assembly bank withdrawal from a suberitical or low power startup condition accident (15.4.1), and spectrum of rod cluster control assembly ejection accidents (15.4.8). All three of these accident scenarios are bounded by cases at 0% RTP l taking credit for the PR low setpoint trip and cases at > 10% RTP taking credit for the PR high setpoint trip. The uncontrolled rod cluster control assembly bank withdrawal from power accident (15.4.2) analyses are performed at initial power levels of 10%,
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1 U. S.. Nuclear Regulatory Commission Attachment 4 April 6,* 1999 Page 2 50%, and 100% RTP to demonstrate that acceptable results are obtained for a range of initial power levels.. For this accident, the PR neutron flux high setpoint' trip, high pressurizer pressure trip, overpower delta-T (OPDT) trip and overtemperature delta-T (OTDT) trip provide core protection. With the P-10 reset function changed to as low as 7% RTP, the conclusions of Section 15.4.2 analysis would not change. Since the uncontrolled bank withdrawal event.is analyzed from both zero power and 10% RTP, all.1 < power initial conditions are adequately bounded.
Therefore, the proposed changes will not increase the probability l or consequences of an accident previously evaluated.
Criterion 2 - Would operation of the facility in accordance with the requested amendment create the possibility of a new or l different kind of acuident from any previously evaluated?
The proposed changes to the allowable values will provide adequate deadbands between the trip and reset setpoints as_well as adequate margin for instrument drift. The reactor trip system overpower trips continue to perform their safety function as assumed in safety analyses. Only the permissives (P-6 and P-10) for blocking and unblocking of overpower. reactor trips are changed. The l proposed changes will not invalidate any of the UFSAR accident l analyses. The proposed changes will not introduce any new failure l modes. Therefore, the proposed changes will not create the possibility of a new or different kind of accident from any previously evaluated.
l l Criterion 3 - Would operation of the facility in accordance with l l
'the requested amendment involve a significant reduction in a margin of safety?
The proposed changes involve lowering the Technical Specification allowable values associated with the P-10 and P-6 permissives for blocking and unblocking of reactor overpower trips. The lowering of these allowable values is not considered a significant reduction since it is just enough to accommodate a deadband recommended by Westinghouse and a margin for instrument drift.
l The proposed changes will not invalidate any UFSAR Chapter 15 accident analyses. Therefore, the proposed changes will not involve a significant reduction in a margin of safety.
U. S. Nuclear Regulatory Commission Attachment 5
' April 6, 1999 Page 1 Envirorunental Assessment / Impact Statement Pursuant to 10 CFR 51.22(b), an evaluation of this license amendment request has been performed to determine whether or not it meets the criteria for categorical exclusion set forth in 10 CFR 51.22 (c)(9) of the regulations.
1 This proposed amendment to the McGuire Units 1 and 2 Technical Specifications revises the allowable values for permissives P-10 (power range neutron flux) and P-6 (intermediate range neutron flux) associated with blocking and unblocking of reactor overpower trips. The new allowable values provide adequate deadbands as recommended by Westinghouse for the trip and reset j setpoints as well as adequate margin for instrument drift. l Operation of the facility in accordance with this amendment has l been reviewed and determined not to involve a significant hazards j consideration. The reactor protection interlocks are provided to '
ensure reactor trips are in the correct configuration for the ,
current unit status. They back up operator actions to ensure protection system functions are not bypassed during unit conditions under which the safety analysis assumes the functions are not bypassed, and have no direct impact on any effluent generation or control systems. The changes in allowable values for the P-10 and P-6 interlocks do not impact the type or quantity at effluents from the station. The' proposed changes to '
the allowable values do not impact individual or cumulative occupational radiation exposure.
It has been determined that there is:
- 1) No significant hazards consideration (see Attachment 4);
- 2) No significant change in the types, or significant increase in the amounts, of any effluents that may be released offsite; and
- 3) No significant increase in individual or cumulative occupational radiation exposures involved.
Therefore, this amendment to the McGuire Technical Specifications meets the criteria of 10 CFR 51.22 (c)(9) for categorical excl'usion from an environmental impact statement.
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