ML20207G483
| ML20207G483 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 12/23/1986 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20207G393 | List: |
| References | |
| NUDOCS 8701070311 | |
| Download: ML20207G483 (23) | |
Text
_.
1 ENCLOSURE 1 PROPOSED TECHNICAL SPECIFICATION CHANGES SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 e
DCCKET NOS. 50-327, -328 (TVA SQN TS 75)
INCREASE IN RWST VALVE STROKE TIME LIST OF AFFECTED PAGES Unit 1 3/4 3-29 3/4 3-30 3/4 3-31 3/4 3-33 Unit 2 3/4 3-29 3/4 3-30 3/4 3-31 3/4 3-33 0
8701070311 861223
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J TABLE 3.3-5 ENGINEERED SAFETY FEATURES RESPONSE TIMES INITIATING SIGNAL AND FUNCTION RESPONSE TIME IN SECONOS 1.
Manual Not Applicable a.
Safety Injection (ECCS)
Feedwater Isolation Not Applicable Reactor Trip (SI)
Not Applicable
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Containment Isolation-Phase "A" Not Applicable Containment Ventilation Isolation Not Applicable Auxiliary Feedwater Pumps Not Applicable Essential Raw Cooling Water System Not Applicable Emergency Gas Treatment System Not Applicable b.
Containment Spray Not Ap,olicable Containment Isolation-Phase "B" Not Applicable Containment Ventilation Isolation Not Applicable v
Containment Air Return Fan Not Applicable c.
Containment Isolation-Phase "A" Not Applicable Emergency Gas Treatment System Not Applicable Containment Ventilation Isolation Not Applicable d.
Steam Line Isolation Not Applicable 2.
Containment Pressure-High gg a.
Safety Injection (ECCS) ith9 b.
Reactor Trip (from SI) 1 3.0 c.
Feedwater Isolation
< 8.0(2)
~
d.
Containment Isolation-Phase "A"(3) 1 18.0(8)/28.0(9) e.
Containment Ventilation Isolation Not Applicable FP f.
Auxiliary Feedwater Pumps 1 60 g.
Essential Raw Cooling Water System 1 65.0(8)/75.0(9) h.
Emergency Gas Treatment System 1 38.0('}
SEQUOYAH - UNIT 1 3/4 3-29 SEP 171980 2
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v TABLE 3.3-5 (Continued)
ENGINEERED SAFETY FEATURES RESPONSE TIMES
, INITIATING. SIGNAL AND FUNCTION RESPONSE TIME IN SECONDS 3.
Pressurizer Pressure-Low JJ.O W
a.
Safety Injection (ECCS) 1 27c8(1)/43.0(7) b.
Reactor Trip (from SI) 1 3.0 c.
Feedwater Isolation
< 8.0(2) d.
Containment Isolation-Phase "A"(3) 18.0(8)
~
e.
Containment Ventilation Isolation Not Applicable f.
Auxiliary Feedwater Pumps 1 60 g.
Essential Raw Cooling Water System 1 65.0(8)/75.0(9) h.
Emergency Gas Treatment Systen.
I 28.0(8) 4.
Differential Pressure Between Steam Lines-High g
g a.
Safety Injection (ECCS) i 13.0( )/23:G(1) b.
Reactor Trip (from'SI)
< 3.0 c.
Feedwater Isolation
< 8.0(2) s.
d.
Containment Isolation-Phase "A"I3) 18.0(8)/28.0(9) e.
Containment Ventilation Isolation Not Applicable f.
Auxiliary Feedwater Pumps 1 60 g.
Essential Raw Cooling Water System 5 65.~0(8)/75.0(9)
FP h.
Emergency Gas Treatment System 1 38.0(9) 5.
Steam Flow in Two Steam Lines - Hioh Coincident with T
--Low-Low a.
Safety Injection (ECCS) i 15.0(7)/25t&(1) b.
Reactor Trip (from SI) 1 5.0 c.
Feedwater Isolation
< 10.0(2) d.
Containment Isolation-Phase "A"(3) 20.0(8)/30.0(9) e.
Containment Ventilation Isolation Not Applicable f.
Auxiliary Feedwater Pumps 1 60 g.
Essential Raw Cooling Water System 1 67.0(8)/77.0(9) h.
Steam Line Isolation
< 10.0 59) i.
Emergency Gas Treatrhent System 40.0 SEQUOYAH - UNIT 1 3/4 3-30 SEP 171980 i
V TABLE 3.3-5 (Continued)
ENGINEERED SAFETY FEATURES RESPONSE TIMES INITIATING'ilGNALANDFUNCTION RESPONSE TIME IN SECONOS 6.
Steam Flow in Two Steam Lines-High Coincident with Steam Line Pressure-Low 2&o a,b a.
Safety Injection (ECCS) 1 -13.0(7)/23?O(1}
b.
Reactor Trip (from SI)
$ 3.0 c.
Feedwater Isolation
< 8.0(2) d.
Containment Isolation-Phase "A"(3)
{18.0(8)/28.0(9) e.
Containment Ventilation Isolation Not Applicable f.
Auxiliary Feedwater Pumps
< 60 g.
Essential Raw Cooling Water System 65.0(8)/75.0(9) h.
Steam Line Isolation
< 8.0 1.
Emergency Gas Treatment System h38.0(9) i 7.
Containment Pressure--High-High a.
< 58.00(9) b.
Containment Isolation, Phase "B" 1 65(9)/75(9) c.
Steam Line Isolation 1 7.0 d.
Containment Air Return Fan
> 540.0 and i 660 R16 8.
Steam Generator Water Level--High-High a.
Turbine Trip-Reactor Trip 52.5 b.
Feedwater Isolation i 11.0(2) 9.
Main Steam Generator Water Level -
Low-Low a.
Motor-driven Auxiliary
< 60.0 Feedwater Pumps (4) b.
Turbine-driven Auxiliary 5 60.0 Feedwater Pumps (5)
MAR 251992 SEQUOYAH - UNIT 1 3/4 3-31 Amendment No. 12
.J
INSTRUMENTATION TABLE 3.3-5 (Continued) v
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TABLE NOTATION (1) Diesel generator starting and sequence loading delays included. Response time limit includes opening of valves to establish SI path and attainment of discharge pressure for centrifugal charging pumps, SI and RHR pumps.
(2) Using air operated valve (3) The following valves are exceptions to the response times shown in the table and will have the values listed in seconds for the initiating signals and function indicated:
FCh-26-240,-243 Valves:
Response times:
2.d. 21
/ 31(9) 3.d. 22 4.d. 21(8)/ 31I9) 1 3
Valves:
FCV-61-96, -97, -110, -122, -191, -192, -193, -194 Response times:
2.d. 31((0) 8)
3.d. 32 4.d. 31(8) 5.d. 34(8) 6.d. 31(8)
Valve: FCV-70-143 3.d. C2(0)/71(9) 2.d. 61(0)
Response times:
1:': afE' '{U A
E.d. 61(8)f71(9)
(4) On 2/3 any Steam Generator (5) On 2/3 in 2/4 Steam Generator (6) Radiation detectors for Containment Ventilation Isolation may be excluded from Response Time Testing.
,,j ciw;p (7) Diesel generator starting and sequence loadis:g delays not includedj0ffsite power available.
Response time limit includes openingsof valves to establish l SI path and attainment of discharge pressure for centrifugal charging pumps.
(8) Diesel generator starting and sequence loading delays not included.
Response
time limit includes operating time of valves.
(9) Diesel Generator st.arting and sequence loading delays included.
Response
time limit inclades operating time of valves.
December 23, 1982 SEQUOYAH - UNIT 1 3/4 3-33 Amendment No.17 O
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1 TABLE 3.3-5 s'
ENGINEERED SAFETY FEATURES RESPONSE TIMES IN!TIATING SIGNAL AND FUNCTICN RESPONSE TIME IN SECONOS 1.
Manual a.
Safety Injection (ECCS)
Not Applicable Not Applicable Feedwater Isolation Reactor Trip (SI)
Not Appifcable Containment Isolation-Phase "A" Not Applicable Containment Ventilation Isolation Not Applicable Auxiliary Feedwater Pumps Not Applicable Es'sential Raw Cooling Water System Not Applicable Emergency Gas Treatment System Not Applicable b.
Containment Spray Not Applicable Containment Isolation-Phase "B" Not Applicable
, Containment Ventilation Isolation Not Applicable Containment Air Return Fan Not Applicable Containment Isolation-Phase "A" Not Applicable c.
Emergency Gas Treatment System Not Applicable Containment Ventilation Isolation Not Applicable d.
Steam Line Isolation Not Applicable 2.
Containment Pressure-High g
l a.
Safety Injection (ECCS) 12F0 f
0) b.
Reactor Trip (from SI)
< 3.0 8.0(2) c.
Feedwater Isolation Containment Isolation-Phase "A"(3)
{18.0(8)/28.0(9) d.
Containment Venti'lation Isolation Not Applicable e.
f.
Auxiliary Feedwater Pumps
< 60 65.0(8)/75.0(9) g.
Essential Raw Cooling Water System
.1.
Emergency Gas Treatment System 1 38.0(9) l l
%d i
SEQUOYAH - UNIT 2 3/4 3-29 l
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TABLE 3.3-5 (Continued)
ENGINEERED SAFETV FEATURES RESPONSE TIMES INITIATING SIGNAL Atl0 FUNCTION RESPONSE tit!E IN SECONOS
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3.
Pressurizer Pressure-Low g
.y a.
Safety Injection (ECCS) 1 #7.0(1)G3*.0(7) b.
Reactor Trip (frcm SI)
< 3.0 c.
Feedwater Isolation 8.0(2) d.
Containment Isolation-Phase "A"(3) 18.0( )
e.
Containment Ventilation Isolation Not Applicable f.
Auxiliary Feedwater Pumps
< 60 g.
Ersential Raw Cooling Water System 65.0(9)/75.0(9) h.
Emergency Gas Treatrient System 1 28.0(8) 4.
Differential Pressure Between Steam Lines-High g,o ggg a.
Safety Injection (ECCS) 1 ESTO(7)/234(1) b.
Reactor Trip (from SI) 1 3.0 c.
Feedwater Isol.ation
< 8.0(2) d.
Containment Is'olation-Phase "A"(3)
}18.0(8)/28.0(9) e.
Containment Ventilation Isolation Not Applicable f.
Auxiliary Feedwater Pumps 5 60 g.
Essential Raw Cooling Water System 1 65.0(9)/75.0(9) h.
Emergency Gas Treatment System 1 38.0(9) 5.
Steam Flow in Two Steam Lines - High Coincident with I
--Low-Low g,3 jg a.
Safety 2 Jection (ECCS) 1 19 0(7)/2510(1) b.
Reactor Trip (from SI) 1 5.0 c.
Feedwater Isolation
< 10.0(2) d.
Containment Isolation-Phase "A"(3)
}20.0(8)/30.0(9) e.
Containment Ventilation Isolation Not Applicable f.
Auxiliary Reedwater Pumps
< 60 g.
Essential Raw Cooling Water System 67.0(8)/77.0(9) h.
Steam Line Isolation
< 10.0 i.
Emergency Gas Trcatment System 40.0(9) e U
SEQUOYAH - UNIT 2 3/4 3-30 t
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TABLE 3.3-5 (Continued)
ENGINEERED SAFETY FEATURES RESPONSE TIMES INITIATING SIGNAL AND FUNCTION RESPONSE TIME IN SECONDS 6.
Steam Flow in Two Steam Lines-High Coincident with 5 team Line Pressure-Low ggg
$43:4(7)jg,fy(1) a.
Safety Injection (ECCS) 3,g b.
Reactor Trip (from SI) 1 3.0 c.
Feedwater Isolation
< 8.0(2) d.
Containment Isolation-Phase "A"(3) 18.0(0)/28.0(9) e.
Containment Ventilation Isolation Not Applicable f.
Auxiliary Feedwater Pumps 1 60 g.
Essential Raw Cooling Water System 1 65.0(8)/75.0(9) h.
Steam Line Isolation
< 8.0 1.
Emerger.cy Gas Treatment System 38.0(9) 7.
Containment Pressure--High-High a.
Containment Spray 1 58.0')(9)
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b.
Containment Iso'lation-Phase "B"
$ 65(8)/75(9) c.
Steam Line Isolation
< 7.0 d.
Containment Air Return Fan
?,540.0 and 1 660 8.
Steam Generator Water Level--High-High a.
Turbine Trip-Reactor Trip 1 2.5 1 11.0(2) b.
Feedwater Isolation 9.
Main Steam Generator Water Level -
Low-Low a.
Motor-driven Auxiliary
< 60.0 Feedwater Pumps (4) b.
Turbine-driven Auxiliary 1 60.0 Feedwater Pumps (5) i e
SEQUOYAH-UNI [2 3/4 3-31
.a
INSTRUMENTATION TABLE 3.3-5 (Continued)
V
. TABLE NOTATION (1) Diesel generator starting and sequence loading delays included. Response time limit includes opening of valves to establish SI path and attainment of discharge pressure for centrifugal charging pumps, SI and RHR pumps.
(2) Using air operated valve (3) The following valves are exceptions to the response times shown in the table and will have the values listed in seconds for the initiating signals and function indicated:
Valves: FCV-26-240, -243 Response times:
2.d. 21(8}/3I('}
I8) 3.d. 22 8)
(9) 4.d. 21 8)
(9) 5.d. 24 8)
(9) 6.d. 21 Valves:
FCV-61-96, -97, -110, -122, -191, -192, -193, -194 Response times 2.d. 31(8) 3.d. 32(8) 4.d. 31(8) 5.d. 34((8)
'v 8) 6.d. 31 Valve:
FCV-70-143 Response times:
2.d.61h/71(9) 3.d. 62 8 (9) 4.d. 61 8 p) 5.d. 64 0 d) 6.d. 61 (4) On 2/3 any Steam Generator (5) On 2/3 in 2/4 Steam Generator (6) Radiation detectors for Containment Ventilation Isolation may be excluded from Response Time Testing.
ani (7) Diesel generator starting and sequence loading delays not included.
> etwa3 l Offsite power available. Response time limit includes opening a valves to establish SI charging pumps. path and attainment of discharge pressure for centrifugalj (8) Diesel generator starting and sequence loading delays not included.
Response time limit includes operating time of. valves.
(9) Diesel generator starting and sequence loading delays included.
Response
time limit includes operating time of valves.
v Deceinber 23, 1982 SEQUOYAH - UNIT 2 3/4 3-33 Amendment No. 8 4 a.eg. n
'41
ENCLOSURE 2 j
i PROPOSED TECHNICAL SPECIFICATION CHANGES SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS. 50-327, -328 (TVA SQN TS 75)
DESCRIPTION AND JUSTIFICATION FOR PPOPOSED INCREASE IN MAXIMUM ALLOWABLE RESPONSE TIME FOR ALIGNMENT OF SAFETY INJECTION SYSTEM VALVES BETWEEN CHARGING PUMPS, VOLUME CONTROL TANK, AND REFUELING WATER STORAGE TANK f
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ENCLOSURE 2 DESCRIPTION OF CHANGE This change would increase the response time for the safety injection system alignment in table 3.3-5 as follows: item 2.a from less than or equal to 27.0 to less than or equal to 32.0; item 3.a from less than or equal to 27.0/13.0 to less than or equal to 32.0/28.0; items 4.a and 6.a from less than or equal to 13.0/23.0 to less than or equal to 28.0/28.0; and item 5.a from less than or equal to 15.0/25.0 to less than or equal to 30.0/30.0.
This change does not affect the applicability of notes to the times given in the table as designated by parenthetical superscripted numbers. Also, note 7 is amended to include all valves in the SI flow path to the charging pump.
REASON FOR CHANGE Flow control valves FCV-62-135 and FCV-62-136 are a part of the Chemical and Volume control System (CVCS) located in the line running from the refueling water storage tank (RWST) to the suction of the charging pumps. The linear i
velocity of the stem of these valves is greater than 36 inches per minute, and are therefore defined as ' fast operating' valves per Westinghouse definition.
As fast operating valves, the valves must be equipped with some device to either limit the impact of the valve internals on the valve seat or to slow the linear speed of the valve internals to less than 36 inches per minute and thereby eliminate the need for an impact-absorbing device on the valve.
Currently, these valves are equipped with brakes at both Sequoyah units.
During a review of safety-related motor operated valves, flow control valves FCV-62-135 and FCV-62-136 were found to have their motor brakes disconnected on unit 1 but connected on unit 2.
Potential reportable occurrence (PRO) number 1-86-105 was generated and forwarded to Division of Nuclear Engineering (DNE) to evaluate the potential for the disabled breaks to affect the operation of the subject valves on unit 1.
DNE concluded that the disabled brakes on valves FCV-62-135 and FCV-62-136 did not adversely affect the operation of those valves, and identified and evaluated three possible corrective actions.
JUSTIFICATION FOR CHANGE The three corrective actions identified, along with brief summary of the i
(
evaluation of those actions, are as follows:
I Option 1 - Reconnect the brakes in unit 1 and leave the brakes in unit 2 connected as is.
Calculation OE2-EEB-CAL 001, revision 4, titled, "AC APS Voltage and Loading Analysis," verifies that adequate starting voltage is available to operate these motor brake coils during an emergency shutdown.
As per procedure, the splice to the motor brake coils must be made to M&AI-7.
The ends of the coil leads are too short to allow oplicing as per this procedure. Thus, this option is not feasible.
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JUSTIFICATION FOR CHANGE (continued)
The replacement of the existing coil with a new component having adequate lead length to accommodate splicing as per M&AI-7 was also explored. Exact replacement coils cannot be purchased; the design of the equipment has improved.
Purchasing new coils would require the generation of required quality assurance (QA) documentation, and therefore increase the cost of the i
coils. The new design coils are several pounds heavier than those currently
- installed; installation of the new coils may require reverification of the seismic anlyses of that line to assure its adequacy. Also, approximately three days would be required to change out each coil.
Thus, when considered i
against option 3, this approach was considered undesirable.
i Option 2 - Replace existing SNB operators with new SB operators with l
spring-pak assemblies.
The replacement of the limitorque SMB-00-10-3600 operators with the i
SM-00-10-3600 model including spring-pak assembly requires significant lead I
time; delivery may be expected within 20 to 22 weeks after placement of the order. Such a lead time is unacceptable in satisfying current restart schedule commitments. As with the purchase of new motor brake coils, j
applicable QA documentation requirements must be met, and added to the cost of the operator. The installation of the SB type operators will add between 50 and 100 pounds to the valve, thereby requiring a reverification of the applicable seismic analyses. Replacement of the SBN operators with the SB operators would also result in significant internal efforts.to modify all applicable documentation to reflect the change. Last, the physical effort j
required to change out the operators is substantial, requiring about three days for each operator. The required QA documentation for the change out is also substantial. Thus, when considered against option 3, this approach was considered undesirable.
Option 3 - Remove the brakes on FCV-62-135 and FCV-62-136 for both j
units 1 and 2 and resear the present operators to operate l
as ' slow-acting' valves (linear valve stem velocity less than 36 inches per minute).
i The manufacturer of the operators advised that researing the existing i
operators may be accomplished such that the maximum allowable valve stroke time is increased from 10 seconds'to 15 seconds. The components required for researing are currently available onsite at Sequoyah.
These components, i
though not required to be so, are environmentally qualified and therefore provide for increased confidence in the reliability of those components.
It is estimated that each valve' operator can be researed in less than four hours and would require significantly less QA documentation compared to Options 1 and 2.
Thus, researing the operators so that FCV-62-135 and FCV-62-136 may be classified as ' slow-acting' valves is the desired action to assure the subject 1
i valves can operate in a safe manner in accomplishing their intended tasks.
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. JUSTIFICATION FOR CHANGE (continued)
The regearing of the operators requires that the increase in time required to accomplish switchover of the charging pump suction from the volume control tank (VCT) to the RWST following a safety injection (SI) signal must be evaluated. That evaluation follows.
STEAM BREAK ANALYSIS CONSIDERATIONS The regearing of the valves would result in the maximum allowable stroke time of the valves being increased by five seconds over the current technical specification requirements. An additional effect has been identified by Westinghouse which has been determined to be applicable to the Sequoyah plants. This effect is that the sequencing of valves on a safety injection signal is such that the VCT isolation valve does not close until the RWST isolation valve is fully open.
Since the VCT is pressurized, the VCT could be the source of the SI flow until the VCT isolation valve is shut. This effect is not included in the finat safety analysis report (FSAR) safety analyses and would result in an increase in the delay time to complete the correct flow path from the RWST for safety injection by an additional 10 seconds.
As a result of evaluating this condition, TVA has determined the following:
1.
There is a check valve in the line between the charging pump suction and the VCT.
The purpose of the check valve is to prohibit flow from running from the suction line into the VCT due to pressure surges.
2.
The VCT is pressurized. However, due to the additional elevation head associated with the position of the RWST with respect to the VCT, the check valve in the line to the VCT will seat no later in the transient than when the valves in the RWST are full open.
This action would isolate the VCT and provide for the charging pumps to draw suction from only the RWST.
TVA has therefore concluded that this condition would not influence safety injection through the charging pumps.
The net result evaluated by Westinghouse is to increase the SI flow path establishment response time by 15 seconds above the current analysis values.
This would affect assumptions in the non-LOCA safety analyses for cases where offsite power is maintained and where offsite power is lost. The only impact on this time delay would be on the steambreak accident which relies upon the borated water to limit the post reactor trip power excursion. Based on the current analysis for the Sequoyah plants which assumes a boron injection tank (BIT) boron concentration of 0 ppm and sensitivity studies performed for similar plants, the additional time delay will be acceptable.
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The additional delay in establishing a flow path occurs early in the transient where reactor coolant system (RCS) pressures are relatively high and SI flow is relatively small due to the SI pump head / flow characteristics. Therefore, the delay occurs at a time where the SI flow is less effective.
2.
With the initial BIT concentration reduced to O ppm, previous sensitivity studies performed for similar plants have shown that significant reductions in the delivery of safety injection flow result in only small perturbations in the analysis results. A specific evaluation of the Sequoyah FSAR Chapter 15 steamline break analysis indicates that there is sufficient margin available in the analysis that the conclusions in the FSAR would be unaffected.
3.
The plant-specific analyses for Sequoyah assume only one safety grade charging pump is available; however, at the pressures indictive of a steam line break, all the safety injecticn pumps of. a given train would l
be available resulting in a significantly higher flowrate of borated water to the RCS.
4.
The steamline break mass / energy release analysis performed for Sequoyah with an initial BIT boron concentration of 0 ppm was found to have no significant effect on the results of the containment temperature / pressure analyses.
The proposed additional delay in providing borated water would not impact these analysis results.
It is Westinghouse's judgement, transmitted to TVA in letter TVA-86-632 dated August 8, 1986, that including the additional 15 second seconds to the SI i
valve alignment time will not have a significant adverse impact on the safety analysis results and that the conclusions of the FSAR will remain valid.
LOCA ANALYSIS CONSIDERATONS LOCA safety analyses are not affected by the increase in response time for establishing the SI flow path.
For a large break LOCA, the alignment will occur prior to the end of blowdown.
Thus, the alignment will be complete prior to water from that line being supplied to the core.
For a small break LOCA, the additional delay in establishing a flow path occurs early in the transient when RCS pressures are relatively high and SI flow is small due to the SI pump head / flow characteristics. Thus, for a small break LOCA, the SI flow occurs at a time in the transient when the flow has a small impact on the RCS.
Therefore, the delay in response time for establishing the SI flow path j
does not affect the LOCA safety analyses.
CLARIFICATION OF VALVES IN SI FLOW PATH Note (7) is amended to account for the closing of the motor-operated valves in the line between the VCT and the charging pumps. Also, the system alignment time for those events covered by note (7) have been modified to include the subject valve response time. The inclusion of these valves in the SI flow path alignment is consistent with the discussion given in IE Information Notice No. 86-80, " Unit Startup With Degraded High Pressure Safety Injection System," dated September 12, 1986.
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. CONCLUSION The researing of the valves in the line between the RWST and charging pumps so that the valves can be classified ' slow operating' valves will eliminate the need for motor brakes and SB-type operators.
Increasing the valve stroke time will increase the response time required to align the SI flow path.
Westinghouse has evaluated the proposed valve stroke time increase and determined that there is no significant adverse impact on safety analyses results, and that conclusions presented in the FSAR remain valid. Thus, it is TVA's position that regearing the valves in the line between the RWST and charging pumps is both acceptable and desirable in providing for the safe, effective operation of those valves.
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i ENCLOSURE 3 PROPOSED TECHNICAL SPECIFICATION CHANGES SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS. 50-327, -328 (TVA SQN TS 75)
Safety evaluation performed by Westinghouse Electric Corporation in support of increasing the maximum allowable response time for alignment of safety injection system valves between charging pumps volume control tank, and refueling water storage tank.
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. WEST 3Rn0USe Pcwer Systerns
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Eir.::tr:: Ccrporation 9:. m E "";. F h*PWvPd. 7~j'-
TVA-86-532 August 3, 1986 Mr. D. W. ni'sca b
.ie f e rer.co s :
Project Engiq.isc
- 1) W GO #CC-41809 Se:.: cyan Nuc: u-Plant
- 2) TVA RD#998355 Tenne::es W ley Autnc-ity
- 3) NS-CPLS-TA-I-85-353 P. O. Sc4 2000 Secay Datsy, Tennessee 37379 Tennessee Valley Authority Sequoyah Nucleai Plait 6
Evaluation of Increased Strcke Time and Secuencina Delays of Safety In$ection System
Dear Mr. Wilson:
Attached for TVA's information and use is Nuclear Safety Evaluation checklist hS-SECL-86-304 which eva10ates increased strcKe time and sequencing delay of the SI system.
This evaluation was performed based on information provided by TVA's Ken Gauthmann.
Our evaluaticn ccncludes that it is" Westinghouse's judgment that including an additicnal IS seconds to the SI valve alignment time will not have a significant adverse impact on the safety analysis results and that the conclusions of the FSAR will remain valid.
Transmittal of this checklist concludes Westinghouse's effort under RD#998356.
Very truly yours, HESTINGHOUSE ELECTRIC CORPORATION l
hG o
L. L. Williams, Manager ESSD Projects Hid South Area
/pab cc:
D. H. Wilson V. A. Bianco J. A. Raulston R. U. Mathieson 30105*
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$$.SEC1.-86-304
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Catczner Referenca N:(s). conversatsens with W A as described in the attached cane Westinghouse Reference No(s)
(Change Control or RFQ as Applicable)
NSCPLSTA-II-86 111 / NSORSTLI-E6 12 0/ NS CR S'"L T-86_ 62 WESTINGHCUSE NUCEAR SAFETY EVALUATION QiECK LIST 1)
NJ1 EAR ILANT(S)
SEbUOYAH UNITS 1 AND 2
- 2) CHECK LIST APPLICABLE TO: INC9EFED STROKE TM AND sol'rNENG M AYS OF SI SYSTEM
- 3) The written safety evaluation of the revised procedure, design change er modification required by 10CFR50.59 has been prepared to the extent required and is attached.
If a safety evaluatien is not required or is incomplete for any reason, explain on page 2.
Parts A and B of this Safety Evaluation Check List are to be ccxnpleted only on the basis of the safety evaluation perfonned.
CHECK LIST - PART A A change to the plant as described in the FSAR7 (3.1) Yes L No (3.2) Yes __ No_L A change to procedures as described in the FSAR7 (3.3) Yes No_L A test or experiment not described in the FSAR7 (3.4) Yes_L No___
A change to the plant technical specifications (Ap'pendix A to the Operating Li nse)?
- 4) CHECK LIST - PART B (Justification fcr Part B ansiers must be included on Page 2.)
(4.1) Yet__ NQ_L Will the probability of an accident previously evaluated in the FSAR be incre.ased?
No_L Will the consequences of an accident greviously (4.2) Yes evaluated in the FSAR be increased?
(4.3) Yes____ NQ_L May the passibility of an accident which is different than any already evalmted in the FSAR be created?
(4.4) Y.et._ No_L Will the probability of a malfunction of equipnent imprtant to safety previously evaluated in the FSAR be increased?
(4.5) Yes NQ_L Will the consequences of a malfmetion of equipnent important to safety previously evaluated in the FSAR be increased?
(4.6) Yes No_L May the passibility of a malfmetion of equipnent important to safety different than any alreacty evaluated in the FSAR be created?
(4.7) Yet Nq_L Will the margin of safety as defined in the bases to any technical specificatien be reduced?
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If th] ansedio any of the bovo questions ara t:1knan, indicato under 5)
RDERXS cnd oxplain belm.
'If the anser to any of the above questions in 4) cannot be anmered in the negative, based on written safety evaluation, the change cannot be approved without an application for license amendment sutr.itted to NRC pursuant to 10CFR50 90
, 5) REMARKS:
The followig)stmnarizes the justificaticn upon the written safety ey aluation, for ansers given in Part B of the Safety Evaluatien Cheek List:
Please see attached safety evaluation.
II)Doctanent(s) containing written safety evaluation:
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FOR FSAR UPDATE Section:
Page(s):
Table (s):
Figure (s):
Reason for/ Description of Qiange:
Prepared by (Nuclear. Safety):
yi A &.
Date:
I6 '
Coordinated with Engineer (s):
Date:
Coordinating Group Manager (s):
Date:
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Nuclear Safety Group Manager:
/
Date:
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SECL-86-304 (CCNT)
EVALUATION FOR INCREASED STRCKE TIE AND SEQUENC!?G CF SI VALVES FOR THE SEQUOYAH NUCLEAF P_ AtJTS 3esetcr Er.gireering, Ken Gauthman frcm T/A was addressing qualificaticn of valves frce r.e 7cluse Centrol Tank (VC'") arc Refuelir.g Water Stcrage Tar.k
(.3lST), anc cetermirec that the trakes on the FWST were not qualified.
Re t.clutien was to insts',1 qualified trakes cr te regear the valve.
Regearing of 1e valve wculd slm the strcke time ar.d therefere celay the alignment cf the FWST with the Charging Pumps which supply Safety Injection rim to the RCS.
Based en discussions with Ken Gauthman, the increase in stroke time was an acditicnal 5 seconds in addition to the current requirenent of 10 seconds (typical of fast acting valves).
An additicnal effect has been identified which has teen determined to be applicable to the Sequoyah plants.
his effect is that the sequencing of valves on a Safety Injecticn signal is such that the VCT isolation valve does not close until the EWST isclaticn valve is fully cpen.
Since the VCT is pressurized, the VCT is the source of the SI fim until the VCT isolaticn valve is shut.
This effect is not included in the FSAR safety analyses and would result in an ircrease in the delay time to complete the correct fim path from the EWST for safety injecticn by 10 seccnds, he net result is to increase the SI fim path establishment response time by 15 seconds ateve the current analysis values.
This wculd affect assumptions in the non-LCCA safety analyses for cases where offsite power is maintained and where offsite power is lost.
The only impact on this time delay would be on the Steambreak accident whf ch relies upon the bcrated water to limit the post reactor ~ trip power excursion.
Based on the current analysis for the Sequoyah plants which asstnes reducticn of the BIT boron concentraticn to O ppn and sensitivities rm on similar plants, the additional time delay will be acceptable.
1)
The additional delay in establishing a fim path occurs early in the transient where RCS pressures are relatively high and SI fim is relatively snaller due to the SI. pump head /flm characteristics.
Therefcre, the delay occurs at a time where the SI fim is less
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effectiv e.
2)
Once the. BIT concentratien has been reduced to O ppn, previous sensitivities have shwn that significant reducticns in the Safety Injecticn rim capabilities result in only snall perturbatiens in the analysis results.
A specific evaluaticn of the Sequoyah FSAR Chapter 15 steamline break analysis indicates that there is sufficient margin available in the analysis that the conclusions in the FSAR would be unaffected.
3)
The analyses assune only one safety grade charging punp is available hwever, at the pressures indicative cf a steamline break, all the safety irdecticn punps of a given train wculd be available resulting in a significantly higher fimrate cf borated water to the BCS.
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SEG.-c6-304 (CCNT)
,,, s 3)
Tha st:antilre trcak mas:/chergy r:1ra 2 analysis with the BI tcren concentraticn reduced hac no significant effect en the results of the contairment temcerature/ pressure analyses.
The additieral delay in previcirg ccratec water wculd not irrcact these analysis results.
- :nculd te r.ctec that the tecnnical specificat;:n fcr te afety injecticn restor.se time wculc ret te Sati:fiec with the ircreasec celay in valve res;cnse time.
In the sfety analysic, ne 3:smpticn is. Tace that the tcrated water ficw path is esta:lished as well as the ficw.
~his shculd be considered in 71A's evaluaticn cf restart rec.uirments with respect to the Sequoyah plants.
It is assuned that either the technical specificaticn would have to be
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satisfied of a justificaticn fcr relaxaticn cf the technical specificaticn wculd be required.
It is Westinghouse's judgement that including the additicral 15 second seconds to the SI valve alignment tirr.e will not have a significant adverse impact on the safety andlysis results and that the conclusions of the FSAR will reain y alid.
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ENCLOSURE 4 PROPOSED TECHNICAL SPECIFICATION CHANGES SEQUOYAh NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS. 50-327 -328 (TVA SQN TS 75)
DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATIONS FOR PROPOSED INCREASE IN MAXIMUM ALLOWABLE RESFONSE TIMES FOR ALIGNMENT OF SAFETY INJECTION SYSTEM VALVES BETWEEN CHARGING PUMPS, VOLUME CONTROL TANK, AND REFUELING WATER STORAGE TANK O
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.4 SIGNIFICANT HAZARDS EVALUATION 1.
Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?
No.
Flow control valves FCV-62-135 and FCV-62-136 are a part of the Chemical and Volume Control System (CVCS) located in the line running from the refueling water storage tank (RWST) to the suction of the charging pumps. These valves serve to isolate the RWST from the charging pumps during normal operation, and allow the charging pumps to draw suction from the RWST in the event of a safety injection (SI) actuation.
Increasing the maximum allowable valve stroke time by five seconds allows these valves to operate safely without either motor brakes or SB type impact-absorbing valve operators. The Westinghouse evaluation of the proposed valve stroke time increase concludes that there is no significant adverse impact on current safety analyses results, and that the conclusions presented in the final safety analyses report (FSAR) remain valid. Therefore, regearing the valves to increase the maximum allowable stroke time of FCV-62-135 and FCV-62-136 by five seconds will provide for these valves to satisfactorily provide for their intended design function with no significant changes in either the probability or consequences of an accident previously evaluated.
i 2.
Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?
No.
The regearing of flow control valves FCV-62-135 and FCV-62-136 presents no modification to testing methods. The components that would be used to accomplish the regearing, although not required to be so, are environmentally qualified and therefore provide for increased confidence in the reliability of those compor.ents. Also, the Westinghouse evaluation concludes that, once valve alignment is accomplished, the system operation will operate as presently expected.
Thus, the proposed researing of the subject valves to increase maximum allowable stroke time by five seconds does not create the possibility of a new or different kind of accident from any accident previously esaluated.
3.
Does the proposed amendment involve a significant reduction in a margin of safety?
i No.
The Westinghouse evaluation of the proposed valve stroke time increase concludes that there is no significant adverse impact on current i
safety analyses results.
It follows that there are also no significant adverse impacts on margin of safety resulting from increasing the maximum allowable stroke time of valves FCV-62-135 and FCV-62-136 by five seconds.
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