ML20196G470

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Proposed Tech Specs Pages Re Amends to Licenses DPR-77 & DPR-79,revising TS to Be Consistent with Rev to ISTS Presently Submitted to NEI TSTF for Submittal as Rev to NUREG-1431
ML20196G470
Person / Time
Site: Sequoyah  Tennessee Valley Authority icon.png
Issue date: 06/24/1999
From:
TENNESSEE VALLEY AUTHORITY
To:
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ML20196G449 List:
References
RTR-NUREG-1431 NUDOCS 9907010169
Download: ML20196G470 (17)
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Text

1

. . l ENCLOSURE 2 y TENNESSEE VALLEY AUTHORITY SEQUOYAH PLANT (SQN)

UNITS 1 AND 2 PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE MARKED PAGES I. AFFECTED PAGE LIST Unit 1 Unit 2 3/4 6-27 3/4 6-28 B 3/4 6-4 B 3/4 6-4 B 3/4 6-5 B 3/4 6-5 II. MARKED PAGES See attached.

9907010169 DR 990624 ADOCK 05000327 PDR

Innert A

_____.._______........_____.-NOTE----------------------------------

If one or more baskets in an ice condenser bay are found to contain

<1071 lbs of ice, a representative sample of 20 additional baskets from the same bay shall be weighed. The average weight of ice in the baskets weighed in the specified bay shall be 2 1071 lbs at a 95% confidence level.

Insert B The weighing program is designed to obtain a representative sample of the ice baskets. The representative sample shall include 6 baskets from each of the 24 ice condenser bays and shall consist of one basket from radial rows 1, 2, 4, 6, 8, and 9. If no basket from a designated row can be obtained for weighing, a basket from the same row of an adjacent bay shall be weighed. The selection criteria and methodology for the weighing of 144 ice condenser baskets was documented in two SERs issued for the licensing of the D. C. Cook Nuclear Facility. The first SER, issued as Supplement 5 of the original D. C. Cook SER on January 16, 1976 (Letter N76007), addressed the weighing of 96 ice baskets and defined the statistical methods for analyzing the data. The second SER was issued as letter N77016 on February 16, 1977 and addressed the reasons for increasing the sample size to 144 ice baskets.

The rows chosen include the rows nearest the inside and outside walls of the ice condenser (rows 1 and ?, and 8 and 9, respectively), where heat transfer into *he ice condenser is most likely to influence sublimation. Verifying the total w"1ght of ice ensures that there is adequate ice to absorb the required amount of ensrgy to mitigate the DBAs.

The total ice weight defined in thic SR is the minimum required ice weight for the beginning of an operating cycle. A sublimation allowance has been provided to ensure sufficient ice is available at the end of the operating cycle for the ice condenser to perform its intended design function.

This SR has been modified by a note that indicates if one or more baskets are found to contain < 1071 lb of ice, a representative sample of 20 additional i baskets from the same bay shall be weighed and that the average weight of ice in l the baskets weighed in the specified bay (the discrepant basket (s), the remaining originally selected baskets, and the 20 additional baskets) shall be 2 1071 lb at a 95% confidence level. Weighing 20 additional baskets from the same bay in the event a Surveillance reveals that one or more baskets contains < 1071 lb ensures that no local zone exists that is grossly deficient in ice. Such a zone could experience early melt out during a DBA transient, creating a path for steam to pass through the ice bed without being condensed. The frequency of 18 months was l based on ice storage tests and the allowance built into the required ice mass over and above the mass assumed in the safety analyses. The average weight figure of 1071 lbs of ice per basket contains either a conservative allowance for ice loss l through sublimation, which has teen determined by plant specific analysis or a 1 defined 15% allowance, which is a factor of 15 higher than assumed for the ice condenser design. The minimum weight figure of 2,082,024 lbs of ice also contains an additional 1% conservative allowance to account for systematic error in weighing instruments. In the event that observed sublimation rates are equal to or lower than design predictions after three years ot operation, the minimum ice basket weights may be adjusted downward. Operating experience has verified that, with the 18 month frequency, the weight requirements are maintained with no significant degradation between surveillances.

l l

l J

CONTAINMENT SYSTEMS SURVEILLANCE REQUIREMENTS (Continued)

c. At least once per 40 months- by lifting and visually inspecting the accessible portions of at least two ice baskets from each 1/3 of the lngC[T)( ice condenser and verifying that the ice baskets are free of detrimental structural wear, cracks, corrosion or other damage. The ice baskets shall be raised at least 10 feet for this inspection.
d. At least once per 18 months by: l R135

. Chemical analyses which verify that at least 9 representative samples of stored ice have a boron concentration of at least R228 1800 ppm as sodium tetraborate and a pH of 9.0 to 9.5.

2. Weighing a representative sample of at least 144 ice basket 3/CE2

^ '-

gret s t r u.u 2 5" " * -- '

rt 1 12 . uo v. .ve. lR228 The representative sample shall include 6 baskets from each of the 24 ice condenser bays and shall be constituted of one basket each from Radial Rows 1, 2, 4, 6, 8 and 9 (or from the same row of an adjacent bay if a basket from a designated row cannot be obtained for weighing) within each bay. If any basket is found to contain less than 1071 pounds of ice, a lR22-8

{}g}g{g  % representative sample of 20 additional baskets from the same bay

  1. shall be weighed. The minimum average weight of ice from the 20 additional baskets and the discrepant basket shall not be less han 1071 nounds/ basket at a 95% level of confidence. l R228 The ice condenser shall also be subdivided into 3 groups of baskets, as follows: Group 1 - bays 1 through 8, Group 2 - bays 9 through 16, and Group 3 - bays 17 through 24. The minimum average ice weight of the sample baskets from Radial Rows 1, 2, 4, 6, 8 and 9 in each group shall not be less than 1071 pounds / basket at a 95% level of confidence. lR228 The minimum total ice condenser ice weight at a 95% level of confidence shall be calculated using all ice basket weights determined during this weighi - rogram and shall not be less than 2,082,024 pounds. lR228 at the beginning of each operating cycle June 10, 1997 SEQUOYAH - UNIT 1 3/4 6-27 Amendment No. 4, 98, 131, 224

CONTAINMENT SYSTEMS BASES 3/4.6.4 COMBUSTIBLE CAS CONTROL l

l The OPERABILITY of the equipment and systems required for the detection and control of hydrogen gas ensures that this equipment will be available to maintcin the hydrogen concentration within containment below its flammable limit during post-LOCA conditions. Either recombiner unit or the hydrogen gg mitigation system, consisting of 68 hydrogen ignitions per unit, is capable of controlling the expected hydrogen generation associated with 1) zirconium-water reactions, 2) radiolytic decomposition of water and 3) corrosion of metals within containment. These hydrogen control systems are designed to mitigate the effects of an accident as described in Regulatory Guide 1.7, " Control of Combustible Gas Concentrations in Containment Following a LOCA", Revision 2 dated November 1978. The hydrogen monitors of Specification 3.6.4.1 are part of the accident monitoring instrumentation in Specification 3.3.3.7 and are R153 designated as Type A, Category 1 in accordance with Regulatory Guide 1.97, Revision 2, " Instrumentation for Light-Water-Cooled Nuclear Power Plants to Assess Plant Conditions During and Following an Accident," December 1980.

The hydrogen mixing systems are provided to ensure adequate mixing of the containment atmosphere following a LOCA. This mixing action will prevent localized accumulations of hydrogen from exceeding the flammable limit.

The operability of at least 66 of 68 ignitors in the hydrogen mitigation system will maintain an effective coverage throughout the containment. This system of ignitors will initiate combustion of any significant amount of hydrogen released after a degraded core accident. This system is to ensure BR burning in a controlled manner as the hydrogen is released instead of allowing it to be ignited at high concentrations by a random ignition source.

3/4.6.5 ICE CONDENSER The requirements associated with each of the components of the ice con-denser ensure that the overall system will be available to provide sufficient pressure suppression capability to limit the containment peak pressure tran-sient to less than 12 psig during LOCA conditions.

3/4.6.5.1 ICE BED l The OPERABILITY of the ice bed ensures that the required ice inventory will 1) be distributed evenly through the containment bays, 2) contain suffi-cient boron to preclude dilution of the containment sump following the LOCA and

3) contain sufficient heat removal capability to condense the reactor system volume released during a LOCA. These conditions are consistent with the asumptions " M in e . __ % alyses.

The minimum wet t figure of 107 ounds of ice pe basket c tains a 15%

et servative allowance for ice loss thr igh sublimation ich is a ' actor of 15

)lR228 hig =r than assumed for he ice condense design. The min um weig - figure of 2,082 024 pounds of ice c'so contains an a ditional 1% cons vative lowance R228 to ace- nt for systematic . ror in weighing 'nstruments. In the

\ A h-Fleplace vvith Insert I3 l June 10, 1997 l SEQUOYAH - UNIT 1 B 3/4 6-4 Amendment No. 4, 5, 131, 149, 224 l

l

CONTAINMENT SYST E Qgjg{g BASES kr event that observed sublimation rates are equal to or lower than design predic-L tions after three years of operation, the minimum ice baskets weight may be 5 f-adjusteddownward. In addition, the number of ice baskets required to be l weighed each 9 months may be reduced after 3 years of operation if such a l Q deuction is su pported by observed sublimation data.

3/4.6.5.2 ICE BED TEMPERATURE MONITORING SYSTEM The OPERABILITY of the ice bed temperature monitoring system ensures that the capability is available for monitoring the ice temperature. In the event the monitoring system is inoperable, the ACTION requirements provide assurance that the ice bed heat removal capacity will be retained within the specified time limits.

3/4.6.5.3 ICE CONDENSER DOORS The OPERABILITY of the ice condenser doors ensures that these doors will open because of the differential pressure between upper and lower containment resulting from the blowdown of reactor coolant during a LOCA and that the blow-down will be diverted through the ice condenser bays for heat removal and thus containment pressure control. The requirement that the doors be maintained BR closed during normal operation ensures that excessive sublimation of the ice will not occur because of warm air intrusion from the lower containment.

If an ice condenser inlet door is physically restrained from opening, the system function is degraded, and immediate action must be taken to restore the opening capability of the inlet door. Being physically restrained from opening is defined as those conditions in which an inlet door B165 is physically blocked from opening by installation of a blocking device or by an obstruction from temporary or permanently installed equipment or is otherwise inhibited from opening such as may result from ice, frost, debris, or increased inlet door opening torque beyond the valves specified in Surveillance Requirement 4.6.5.3.1.

3/4.6.5.4 INLET DOOR POSITION MONITORING SYSTEM The OPERABILITY of the inlet door position monitoring system ensures that ,

the capability is available for monitoring the individual inlet door position. I In the event the monitoring system is inoperable, the ACTION requirements i provide assurance that the ice bed heat removal capacity will be retained within the specified time limits.

3/4.6.5.5 DIVIDER BARRIER PERSONNEL ACCESS DOORS AND EOUIPMENT HATCHES The requirements for the divider barrier personnel access doors and equipment hatches being closed and OPERABLE ensure that a minimum bypass steam flow will occur from the lower to the upper containment compartments during a LOCA. This condition ensures a diversion of the steam through the ice condenser bays that is consistent with the LOCA analyses.

3/4.6.5.6 CONTAINMENT AIR RETUPR FANS l

The OPERABILITY of the containment air return fans ensures that following a LOCA 1) the containment atmosphere is circulated for cooling by the spray l system and 2) the accumulation of hydrogen in localized portions of the contain- l ment structure is minimized.  :

! I i

August 10, 1992 SEQUOYAH - UNIT 1 B 3/4 6-5 Amendment No. 161 l

L. )

CONTAINMENT SYSTEMS SURVEILLANCE REQUIREMENTS (Continued) y At least once per 40 months by lifting and visually inspecting the accessible portions of at least two ice baskets from each 1/3 of the R87 Insert A '

ice condenser and verifying that the ice baskets are free of detri-

-m , mental structural wear, cracks, corrosion or other damage. The ice baskets shall be raised at least 10 feet for this inspection.

d. At least once per 18 months by: lRil8 Chemical analyses which verify that at least 9 representative samples of stored ice have a boron concentration of at least 1800 R215 ppm as sodium tetraborate and a pH of 9.0 to 9.5.
2. Weighing a representative sample of at least 144 ice basket R215 nyww m..- - ~ . . - . . -- - ..- - - - m ._ . . - . -. .a.

The representative sample shall include 6 baskets from each of the 24 ice condenser bays and shall be constituted of one basket i gg}g[g each from Radial Rows 1, 2, 4, 6, 8 and 9 (or from the same row Q of an adjacent bay if a basket from a designated row cannot be obtained for weighing) within each bay. If any basket is found to contain less than 1071 pounds of ice, a representative sample l R215 l of 20 additional baskets from the same bay shall be weighed.

The minimum average weight of ice from the 20 additional baskets  ;

and the discrepant basket shall not be less than 1071 l R215 j 6 man / banker ne a oss 1-1 ne cnefi hm The ice condenser shall also be subdivided into 3 groups of baskets, as follows: Group 1 - bays 1 through 8, Group 2 -bays 9 through 16, and Group 3 - bays 17 through 24. The minimum average ice weight of the sample baskets from Radial Rows 1, 2, 4, 6, 8 and 9 in each group shall not be less than 1071 R215 pounds / basket at a 95% level of confidence.

l The minimum total ice condenser ice weight at a 95% level of j confidence shall be calculate 4 qsing all ice basket weights determined during this weighinc .rogram and shall not be less l

l' R215 than 2,082,024 pounds.

l at the l beginning l ofeach l operating cycle June 10, 1997 SEQUOYAH - UNIT 2 3/4 6-28 Amendment No. 80, 87, 118, 215

CONTAINMENT SYSTEMS BASES 3/4.6.4 COMBUSTIBLE GAS CONTROL The OPERABILITY of the equipment and systems required for the detection and control of hydrogen gas ensures that this equipment will be available to maintain the hydrogen concentration within containment below its flammable limit during post-LOCA conditions. Either recombiner unit or the hydrogen mitigation system, consisting of 68 hydrogen igniters per unit, is capable of BR controlling the expected hydrogen generation associated with 1) zirconium-water reactions, 2) radiolytic decomposition of water and 3) corrosion of metals within containment. These hydrogen control systems are designed to mitigate the effects of an accident as described in Regulatory Guide 1.7, " Control of Combustible Gas Concentrations in Containment Following a LOCA," Revision 2, dated November 1978. The hydrogen monitors of Specification 3.6.4.1 are part of the accident monitoring instrumentation in Specification 3.3.3.7 and are designated as Type A, Category 1 in accordance with Regulatory Guide 1.97, Revision 2, " Instrumentation for Light-Water-Cooled Nuclear Power Plants to R135 Assess Plant Conditions During and Following an Accident," December 1980.

The hydrogen mixing systems are provided to ensure adequate mixing of the containment atmosphere following a LOCA. This mixing action will prevent localized accumulations of hydrogen from exceeding the flammable limit.

The operability of at least 66 of 68 igniters in the hydrogen control distributed ignition system will maintain an effective coverage throughout the BR containment. This system of ignitors will initiate combustion of any signifi-cant amounc of hydrogen released after a degraded core accident. This system is to ensure burning in a controlled manner as the hydrogen is released instead of allowing it to be ignited at high concentrations by a random ignition source.

3/4.6.5 ICE CONDENSER The requirements associated with each of the components of the ice condenser ensure that the overall system will be available to provide sufficient pressure suppression capability to limit the containment peak pressure transient to less than 12 psig during LOCA conditions.

3/4.6.5.1 ICE BED The OPERABILITY of the ice bed ensures that the required ice inventory will 1) be distributed evenly through the cont-inment bays, 2) contain suffi-cient boron to preclude dilution of the containmea" sump following the LOCA and

3) contain suf ficient heat ren.aval capability to condense the reactor system volume released during a LOCA. These conditions are concistent with the assu used in the accident analyses.

The mi'imum weight f gure of 1071 ounds of ice >er basket c ntains a 15% lR215 conservative allowe.nce fo ice loss thr ugh sublimati n which is a factor of 15 higher than ,sumed for th ice condense- design. The minimum wei t figure of )I 2,082,024 pou .s of ice als contains an additional 1% onservative 111owance lR215 to account for systematic e or in weighi g instruments In the )

Replace with Insert B June 10, 1997 SEQUOYAH - UNIT 2 B 3/4 6-4 Amendment No. 21, 118, 135, 215

CONTAINMENT SYSTEMS {}g}g{g BASES v

(

event that observed sublimation rates are equal to or lower than design predictions after three years of operation, the minimum ice baskets weight may be adjusted downward. In addition, the number of ice baskets required to be weighed each 9 months may be reduced after 3 years of operation if such a e reduction is supported by observed sublimation data.

3/4.6.5.2 ICE BED TEMPERATURE MONITORING SYSTEM The OPERABILITY of the ice bed temperature monitoring system ensures that the capability is available for monitoring the ice temperature. In the event the monitoring system is inoperable, the ACTION requirements provide assurance that the ice bed heat removal capacity will be retained within the specified time limits.

3/4.6.5.3 ICE CONDENSER DOORS The OPERABILITY of the ice condenser doors ensures that these doors will '

open because of the differential pressure between upper and lower containment resulting from the blowdown of reactor coolant during a LOCA and that the blow-down will be diverted through the ice condenser bays for heat removal and thus BR containment pressure control. The requirement that the doors be maintained closed during normal operation ensures that excessive sublimation of the ice will not occur becauas of warm air intrusion from the lower containment.

If an ice cindenser inlet door is physically restrained from opening, the system function is degraded, and immediate action must be taken to restore the opening capability of the inlet door. Being physically restrained from opening is defined as those conditi-ons in which an inlet door RISI is physically blocked from opening by installation of a blocking device or by an obstruction from temporary or permanently installed equipment or is otherwise inhibited from opening such as may result from ice, frost, debris, or increased inlet door opening torque beyond the values specified in Surveillance Requirement 4.6.5.3.1.

3/4.6.5.4  ?:NLET DOOR POSITION MONITORING SYSTEM The OPERABILITY of the inlet door position monitoring system ensures that the capability is available for monitoring the individual inlet door position.

In the event the monitoring system is inoperable, the ACTION requirements provide assurance that the ice bed heat removal capacity will be retained within the specified time limits.

3/4.6.5.5 DIVIDER BARRIER PERSONNEL ACCESS DOORS AND EOUIPMENT HATCHES The requirements for the divider bat t ier personnel access doors and equipment hatches being closed and OPEFJ sLE ensure that a minimum bypass steam flow will occur from the lower to the upper containment compartments during a LOCA. This condition ensures a diversion of the steam through the ice condenser bays that is consistent with the LOCA analyses.

3/4.6.5.6 CONTAINMENT AIR RETURN FANS The OPERABILITY of the containment air return fans ensures that following a LOCA 1) the containment atmosphere is circulated for cooling by the spray system and 2) the accumulation of hydrogen in localized portions of the contain-ment structure is minimized.

August 10, 1992 SEQUOYAH - UNIT 2 B 3/4 6-5 Amendment No. 151 l l

l l

9 9 ENCLOSURE 3 TE!!NESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT (SQN)

UNITS 1 AND 2 PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE REVISED PAGES I. AFFECTED PAGE LIST Unit l' Unit 2 3/4 6-27 3/4 6-28 B 3/4 6-4 B 3/4 6-4 B 3/4 4-4a B 3/4 4-4a B 3/4 6-5 B 3/4 6-5 II. REVISED PAGES See attached.

N *

( ("

o .

!  ? CONTAINMENT SYSTEMS t

SURVEILLANCE REQUIREMENTS (Continued)

c. At least once per 40 months by lifting and visually inspecting the accessible portions of at least two ice baskets from each 1/3 of the '

ice condenser and verifying that the ice baskets are free of detrimental structural wear, cracks, corrosion or other damage. The ice baskets shall be raised at least 10 feet for this inspection.

d. At leest once per 18 months by: lR135
1. Chemical analyses which verify that at least 9 representative samples of stored ice have a boron concentration of at least R228 1800 ppm as sodium tetraborate and a pH of 9.0 to 9.5.
2. ---------------------------NOTE--------------------------------

If one or more baskets in an ice condenser bay are found to contain <1071 lbs of ice, a representative sample of 20 additional baskets from the same bay shall be weighed. The average weight of ice in the baskets weighed in the specified bay shall be 21071 lbs at a 95% confidence level.

Weighing a representative sample of at least 144 ice baskets.

. The ice condenser shall also be subdivided into 3 groups of baskets, as follows: Group 1 - bays 1 through 8, Group 2 - bays 9 through 16, and Group 3 - bays 17 through 24. The minimum average ice weight of the sample baskets from Radial Rows 1, 2, 4, 6, 8 and 9 in each group shall not be less than 1071 pounds / basket at a 95% level of confidence. lR228 The minimum total ice condenser ice weight at a 95% level of confidence shall be calculated at the beginning of each operating cycle using all ice basket weights determined during this weighing program and shall not be less than 2,082,024 lR228 pounds.

- l l l l

t 3/4 6-27 Amendment No. 4, 98, 131, 224, SEQUOYAH - UNIT 1 f

1 1

- m o J

CONTAINMENT SYSTEMS BASES 3/4.6.4 COMBUSTIBLE GAS CONTRO4 The OPERABILITY of the equipment and systems required for the detection and control of hydrogen gas ensures that this equipment will be available to maintain the hydrogen concentration within containment below its flammable limit during post-LOCA conditions. Either recombiner unit or the hydrogen BR mitigation system, consisting of 68 hydrogen ignitions per unit, is capable of controlling the expected hydrogen generation associated with 1) zirconium-water reactions, 2) radiolytic decomposition of water and 3) corrosion of metals within containment. These hydrogen control systems are designed to mitigate the effects of an accident as described in Regulatory Guide 1.7, " Control of Combustible Gas Concentrations in Containment Following a LOCA", Revision 2 dated November 1978. The hydrogen monitors of Specification 3.6.4.1 are part of the accident monitoring instrumentation in Specification 3.3.3.7 and are R153 designated as Type A, category 1 in accordance with Regulatory Guide 1.97, Revision 2, " Instrumentation for Light-Water-Cooled Nuclear Power Plants to Asaess Plant Conditions During and Following an Accident," December 1980.

The hydrogen mixing systems are provided to ensure adequate mixing of the containment atmosphere following a LOCA. This mixing action will prevent localized accumulations of hydrogen from exceeding the flammable limit.

The operability of at least 66 of 68 ignitors in the hydrogen mitigation system will maintain an effective coverage throughout tha containment. This system of ignitors will initiate combustion of any significant amount of hydrogen released after a degraded core accident. This system ia to ensure BR burning in a controlled manner as the hydrogen is released instead of allowing it to be ignited at high concentrations by a random ignition source.

3/4.6.5 ICE CONDENSER The requirements associated with each of the components of the ice con-denser ensure that the overall system will be available to provide su;ficient pressure suppression capability to limit the containment peak pressure tran-sient to less than 12 psig during LOCA conditions.

3/4.6.5.1 ICE BED The OPERABILITY of the ice bed ensures that the required ice inventory will 1) be distributed evenly through the containment bays, 2) contain suffi-cient boron to preclude dilution of the containment sump following the LOCA and l

3) contain sufficient heat removal capability to condense the reactor system j volume released during a LOCA. These conditions are consistent with the assumptions used in the accident analyses.

The weighing program is designed to obtain a representative sample of the ice baskets. The representative sample shall include 6 baskets from each of whe 24 ice condenser bays and shall consist of one basket from radial rows 1, 2, 4, 6, 8, and 9. If no basket from a designated row can be obtained for weighing, a basket from the same row of an adjacent bay shall be weighed. The selection criteria and methodology for the weighing of 144 ice condenser baskets was documented in two SERs issued for the licensing of the D. C. Cook Nuclear Facility. The first SER, issued as Supplement 5 of the original D. C. Cook SER on January 16, 1976 (Letter N76007), addressed the weighing of 96 ice baskets and defined the statistical methods for analyzing the data. The second SER was issued as letter N77016 on February 16, 1977 and addressed the reasons for increasing the sample size to 144 ice baskets.

SEQUOYAH - UNIT 1 B 3/4 6-4 Amendment No. 4, 5, 131, 149, 224,

. . l

. s CONTAINMENT SYSTEMS r

BASES 3/4.6.5.1 ICE BED (continued)

The rows chosen include the rows nearest the inside and outside walls of the ice condenser (rows 1 and 2, and 8 and 9, respectively) , where heat

transfer into the ice condenser is most likely to influence sublimation. ,

l Verifying the total weight of ice ensures that there is adequate ice to absorb the required amount of energy to mitigate the DBAs.

t i

l The total ice weight defined in this SR is the minimum required ice weight l for the beginning of an operating cycle. A sublimation allowance has been j provided to ensure sufficient ice is available at the end of the operating cycle for the ice condenser to perform its intended design function.

This SR has been modified by a note that indicates if one or more baskets are found to contain < 1071 lb of ice, a representative sample of 20 additional baskets from the same bay shall be weighed and that the average weight of ice in the baskets weighed in the specified bay (the discrepant basket (s), the remaining originally selected baskets, and the 20 additional baskets) shall be 1 1071 lb at a 95% confidence level. Weighing 2J additional baskets from the same bay in the event a surveillance reveals ther one or more baskets contains

< 1071 lb ensures that no local zone exists th:c is grossly deficient in ice.

Such a zone could experience early melt out during a DBA transient, creating a path for steam to pass through the ice bed witheit oaing condensed. The Frequency of 18 months was based on ice storage tests and the allowance built into the required ice mass over and above the mass assumed in the safety analyses. The average weight figure of 1071 lbs of ice per basket contains either a conservative allowance for ice loss through sub?.imation which has been determined by plant specific analysis or a defined 15% L'lowance which is a factor of 15 higher than assumed for the ice condenser desxqn. The minimum weight figure of 2,082,024 lbs of ice also contains~an additjonsl 1%

conservative allowance to account for systematic error in weiyting instruments.

In the event that observed sublimation rates are equal to or leser than design predictions after three years of operation, the minimum ice be-ke: weights may be adjusted downward. -Operating experience has verified that, with the 18 month Frequency, the weight requirements are maintained with no significant degradation between surveillances.

SEQUOYAH - UNIT 1 B 3/4 6-4a Amendment No.

E . .

CONTAINMENT SYSTEMS BASES I

3/4.6.5.2 ICE BED TEMPERATURE MONITORING SYSTEM The OPERABILITY of the ice bed temperature monitoring system ensures that the capability is available for monitoring the ice temperature. In the event the monitoring system is inoperable, the ACTION requirements provide assurance that the ice bed heat removal capacity will be retained within the specified time limits.

3/4.6.5.3 ICE CONDENSER DOORS l The OPERABILITY of the ice condenser doors ensures that these doors will open because of the differential pressure between upper and lower containment resulting from the blowdown of reactor coolant during a LOCA and that the blow-down will be diverted through the ice condenser bays for heat removal and thus BR containment pressure control. The requirement that the doors be maintained closed during normal operation ensures that excessive sublimation of the ice will not occur because of warm air intrusion from the lower containment.

If an ice condenser inlet door is physically restrained from opening, the system function is degraded, and immediate action must be taken to restore the opening capability of the inlet door. Being physically restrained from opening is defined as those conditions in which an inlet door is physically blocked R165 from opening by. installation of a blocking device or by an obstruction from temporary or permanently installed equipment or is otherwise inhibited from opening such as may result from ice, frost, debris, or increased inlet door opening torque beyond the valves specified in Surveillance Requirement 4.6.5.3.1.

3/4.6.5.4 INLET DOOR POSITION MONITORING SYSTEM The OPERABILITY of the inlet door position monitoring system ensures that the capability is available for monitoring the individual inlet door position.

In the event the monitoring system is inoperable, .the ACTION requirements provide assurance that the ice bed heat removal capacity will be retained within the specified time limits.  !

3/4.6.5.5 DIVIDER BARRIER PERSONNEL ACCESS DOORS AND EOUIPMENT HATrH_ES The requirements for the divider barrier personnel access doors and equipment hatches being closed and OPERABLE ensure that a minimum bypass steam  !

flow will occur from the lower to the upper containment compartments during a LOCA. This condition ensures a diversion of the steam through the ice condenser bays that is consistent with the LOCA analyses.

l 3/4.6.5.6 CONTAINMENT AIR RETURN FANS L

The OPERABILITY of the containment air return fans ensures that following a LOCA 1) the containment atmosphere is circulated for cooling by the spray t system and 2) the accumulation of hydrogen in localized portions of the l containment structure is minimized.

SEQUOYAH - UNIT 1 B 3/4 6-5 Amendment No. 161, l

l

f"s .

> . 1 CONTAINMENT SYSTEMS SURVEILLANCE REQUIREMENTS (Continued)

c. At least once per 40 months by lifting and visually inspecting the accessible portions of at least two ice baskets from each 1/3 of the R87 ice condenser and verifying tha,t the ice baskets are free of detri- .

mental structural wear, cracks, corrosion or other damage. The ice I

baskets shall be raised at least 10 feet for this inspection.

d. At least once per 18 months by: lR118
1. Chemical analyses which verify that at least 9 representative samples of stored ice have a boron concentration of at least R215 ,'

1800 ppm as sodium tetraborate and a pH of 9.0 to 9.5.

i

2. -- ---------------------- -NOTE--------------------------------

If one or more baskets in an ice condenser bay are found to contain <1071 lbs of ice, a representative sample of 20 additional baskets from the same bay shall be weighed. The average weight of ice in the baskets weighed in the specified bay shall be 2 1071 lbs at a 95% confidence level. j Weighing a representative sample of at least 144 ice baskets.

The ice condenser shall also be subdivided into 3 groups of baskets, as follows: Group 1 - bays 1 through 8, Group 2 -bays 9 through 16, and Group 3 - bays 17 through 24. The minimum average ice weight of the sample baskets from Radial Rows 1, 2, 4, 6, 8 and 9 in each group shall not be less than 1071 pounds / basket at a 95% level of confidence. lR215 The minimum total ice condenser ice weight at a 95% level of confidence shall be calculated at the beginning of each operating cycle using all ice basket weights determined during this weighing program and shall not be less than 2,082,024 R215 pounds. .

4 SEQUOYAH - UNIT 2 3/4 6-28 Amendment No. 80, 87, 118, 215,

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CONTAINMENT SYSTEMS BASES 3/4.6.4 COMBUSTIBLE GAS CONTROL The OPERABILITY of the equipment and systems required for the detection and control of hydrogen gas ensures that this equipment will be available to maintain the hydrogen concentration within containment below its flammable limit during post-LOCA conditions. Either recombiner unit or the hydrogen l mitigation system, consisting of 68 hydrogen igniters per unit, is capable of BR controlling the expected hydrogen generation associated with 1) zirconium-water reactions, 2) radiolytic decomposition of water and 3) corrosion of metals within containment. These hydrogen control systems are designed to mitigate the )

effects of an accident as described in Regulatory Guide 1.7, " Control of Combustible Gas Concentrations in Containment Following a LOCA," Revision 2, dated November 1978. The hydrogen monitors of Specification 3.6.4.1 are part of the accident monitoring instrumentation in Specification 3.3.3.7 and are designated as Type A, Category 1 in accordance with Regulatory Guide 1.97, Revision 2, " Instrumentation for Light-Water-Cooled Nuclear Power Plants to R135 Assess Plant Conditions During and Following an Accident," December 1980.

The hydrogen mixing systems are provided to ensure adequate mixing of the containment atmosphere following a LOCA. This mixing action will prevent localized accumulations of hydrogen from exceeding the flammable limit.

The operability of at least 66 of 68 igniters in the hydrogen control distributed ignition system will maintain an effective coverage throughout the BR containment. This system of ignitors will initiate combustion of any signifi-cant amount of hydrogen released after a degraded core accident. This system is to ensure burning in a controlled manner as the hydrogen is released instead of allowing it to be ignited at high concentrations by a random ignition source.

3/4.6.5 ICE CONDENSER The requirements associated with each of the components of the ice condenser ensure that the overall system will be available to provide sufficient pressure suppression capability to limit the containment peak pressure transient to less than 12 psig during LOCA conditions.

3/4.6.5.1 ICE BED The OPERABILITY of the ice bed ensures that the required ice inventory will 1) be distributed evenly through the containment bays, 2) contain suffi-cient boron to preclude dilution of the containment sump following the LOCA and

3) contain sufficient heat removal capability to condense the reactor system volume released during a LOCA. These conditions are consistent with the assumptions used in the accident analyses. j l

The weighing program is designed to obtain a representative sample of the ice baskets. The representative sample shall include 6 baskets from each 3

of the 24 ice condenser bays and shall consist of one basket from radial rows

1, 2, 4, 6, 8, and 9. If no basket from a designated row can be obtained for weighing, a basket from the same row of an adjacent bay shall be weighed. The selection criteria and methodology for the weighing of 144 ice condenser baskets was documented in two SERs issued for the licensing of the D. C. Cook Nuclear Facility. The first SER, issued as Supplement 5 of the original D. C. Cook SER on January 16, 1976 (Letter N76007), addressed the weighing of 96 ice baskets and defined the statistical methods for analyzing the data. The second SER was issued as letter N77016 on February 16, 1977 and addressed the reasons for increasing the sample size to 144 ice baskets.

SEQUOYAH - UNIT 2 B 3/4 6-4 Amendment No. 21, 118, 135, 215, 1

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,QQNTAINMENT SYSTEMS BASES 3/4.6.5.1 ICE BED (Continued)

The rows chosen include the rows nearest the inside and outside walls of the ice condenser (rows 1 and 2, and 8 and 9, respectively), where heat trancfer into the ice condenser is most likely to influence sublimation.

I Verifying the total weight of ice ensures that there is adequate ice to absorb the required amount of energy to mitigate the DBAs.

The total ice weight defined in this SR is the minimum required ice weight for the beginning of an operating cycle. A sublimation allowance has been provided to ensure sufficient ice is available at the end of the operating cycle for the ice condenser to perform its intended design function.

This SR has been modified by a note that indicates if one or more baskets are found to contain < 1071 lb of ice, a representative sample of 20 additional baskets from the same bay shall be weighed and that the average weight of ice in the baskets weighed in the specified bay (the discrepant basket (s), the remaining originally selected baskets, and the 20 additional baskets) shall be ,

2 1071 lb at a 95% confidence level. Weighing 20 additional baskets from the j same bay in the event a Surveillance reveals that one or more baskets contains

< 1071 lb ensures that no local zone exists that is grossly deficient in ice. l Such a zone could experience early melt out during a DBA transient, creating a l path for steam to pass through the ice bed without being condensed. The 1 Frequency of 18 months was based on ice storage tests and the allowance built into the required ice mass over and above the mass assumed in the safety I

analyses. The average weight figure of 1071 lbs of ice per basket contains either a conservative allowance for ice loss through sublimation which has been determined by plant specific analysis or a defined 15% allowance which is a l factor of 15 higher than assumed for the ice condenser design. The minimum weight figure of 2,082,024 lbs of ice also contains an additional 1%

conservative allowance to account for systematic arror in weighing instruments.

In the event that observed sublimation rates are equal to or lower than design predictions after three years of operation, the minimum ice basket weights may be adjusted downward. Operating experience has verified that, with the 18 month Frequency, the weight requirements are maintained with no significant degradation between surveillances.

SEQUOYAH - UNIT 2 B 3/4 6-4a Amendment No.

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. e CON"AINMENT SYSTEMS BASES 3/4.6.5.2 ICE BED TEMPERATURE MONITORING SYSTEM The OPERABILITY of the ice bed temperature monitoring system ensures that the capability is available for monitoring the ice temperature. In the event the monitoring system is inoperable, the ACTION requirements provide assurance that the ice bed heat removal capacity will be retained within the specified time limits.

3/4.6.5.3 ICE OONDENSER DOORS The OPERABILITY of the ice condenser doors ensures that these doors will open because of the differential pressure between upper and lower containment resulting from the blowdown of reactor coolant during a LOCA and that the blow-down will be diverted through the ice condenser bays for heat removal and thus BR containment pressure control. The requirement that the doors be maintained closed during normal operation ensures that excessive. sublimation of the ice will not occur because of warm air intrusion from the lower containment.

If an ice cindenser inlet door is physically restrained from opening, the system function is degraded, and immediate action must be taken to restore the opening capability of the inlet door. Being physically restrained from opening is defined as those conditions in which an inlet door is physically blocked R151 from opening by installation of a blocking device or by an obstruction from temporary or permanently installed equipment or is otherwise inhibited from opening such as may result from ice, frost, debris, or increased inlet door opening torque beyond the values specified in Surveillance Requirement 4.6.5.3.1.

3/4.6.5.4 INLET DOOR POSITION MONITORING SYSTEM The OPERABILITY of the inlet door position monitoring system ensures that the capability is available for monitoring the individual inlet door position.

In the event the monitoring system is inoperable, the ACTION requirements provide assurance that the ice bed heat removal capacity will be retained within the specified time limits.

3 /4. 6. 5. 5 DIVIDER BARRIER PERSONNEL ACCESS DOORS AND EOUIPMENT HATCHES The requirements for the divider barrier personnel access doors and equipment hatches being closed and OPERABLE ensure that a minimum bypass steam flow will occur from the lower to the upper containment compartments during a LOCA. This condition ensures a diversion of the steam through the ice condenser bays that is consistent with the LOCA analyses.

3/4.6.5.6 CONTAINMENT AIR RETURN FANS The OPERABILITY of the containment air return fat 4s ensures that following a LOCA 1) the containment atmosphere is circulated for cooling by the spray system and 2) the accumulation of hydrogen in localized portions of the contain-ment structure is minimized.

SEQUOYAH - UNIT 2 B 3/4 6-5 Amendment No. 151,

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