ML20101M474
| ML20101M474 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 04/03/1996 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML20101M468 | List: |
| References | |
| NUDOCS 9604050394 | |
| Download: ML20101M474 (14) | |
Text
_ __ _
.. ~ _
CONTAINMENT SYSTEMS
.7 ggf j ygo g HYDROGEN "ITICATION SYSTEM LIMITING CONDITION FOR OPERATION
/
t
+
i 3.6.4.3 Both trains of the Hydrogen Mitig: tion-System shall be OPERABLE.
APPLICABILITY: MODES I and 2.
geenAc.s een*
ACTION.
PAR *
- A A P t+
Wnk
/
y-ruwe PAa44*e9 i ain of the Hydrogen Mitigation System ino e ore the inoperable tra LE status w decrease the surveillance interval of S gif.icath; 4...
92 days to 7 days on the OPERABLE
.__tn?s mdTT fie inoperable train is return status.
SURVEILLANCE REQUIREMENTS 4.6.4.3 Each tr in o J,he,Nydrog_n -Mitig:tien_ System shall be demonstrated e
OPERA 8LE:
cw w 65 y "eee jac+1
^t h::t=Ahce per 92 days by energizing the supply breakirs and a.
F ify, tag Jta ca^orrS To "c"t at least 34 of 35 igniters are energized %
l
)
ce per 18 months by verifying the temperature of each igniter i a minimum of 1700*F.
x
- 9 SEAT 3ntsn1ENT 1
- c. pas to Ep.otA k*TTMW UPPER CME O
9 AGE 4 ' +Ir.epereble igriter: =:t act b: en c:rr;;;:ndia; r:t;&ct circutt: which
-previd cover:g: fer th: t r r gien 3>sceTE STATEm ENT WW CATAWBA - UNITS 1 & 2 3/4 6-40 Amendment No.
(Unit 1)
Amendment No.
(Unit 2) 9604000394 960403 PDR ADOCK 05000413 p
CONTAINMENT SYSTEMS BASES 3/4.6.2 DEPRESSURIZATION AND COOLING SYSTEMS The OPERABILITY of the Containment Spray System ensures that containment depressurization and cooling capability will be available in the event of a LOCA. The pressure reduction and resultant lower containment leakage rate are consistent with the assumptions used in the safety analyses.
However, the Containment Spray System also provides a mechanism for removing iodine from the containment atmosphere, and therefore the time requirements for restoring an inoperable Spray System to OPERABLE status have been maintained consistent with those assigned other inoperable ESF equipment.
3/4.6.3 CONTAINMENT ISOLATION VALVES The OPERABILITY of the containment isolation valves ensures that the containment atmosphere will be isolated from the outside environment in the event of a release of radioactive material to the containment atmosphere or pressurization of the containment and is consistent with the requirements of GDC 54 through 57 of Appendix A to 10 CFR Part 50.
Containment isolation within the time limits specified for those isolation valves designed to close automatically ensures that the release of radioactive material to the environ-ment will be consistent with the assumptions used in the analyses for a LOCA.
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 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 consistent with the recommendations of Regulatory Guide 1.7, " Control of Combustible Gas Concentrations Following a LOCA," March 1971.
NLhe OPERABILITY of at least 34 of 35 igniters per train (68 of 70 f
-l both t Tr res that the Distributed Ignition System will a n an effective covera hout the containment provide t wo inoperable ignitors are not on corres redundant s which provide coverage
,._y.
for the same region. This system o s will initiate combustion of any significant amount of hydr eased after aded core accident.
This system is to ensu ng in a controlled manner as rogen is released instead A T6 wing it to be ignited at high concentrations by m
) gnttlon sourc,e y
p p u e.e ornas 9a w A*PH gm atAc. web P M,a1 FeA rHe. e>MES S Ec.Tio A)
CATAWBA - UNITS 1 & 2 8 3/4 6-4 Amendment No.136 (Unit 1)
Amendment No.130 (Unit 2)
Insertions for Technical Specification 3.6.4.3 Paranraoh 1 With one train of the Hydrogen Ignition System inoperable:
- a. Restore the inoperable train to OPERABLE status within 7 days, OR
- b. Perform surveillance requirement 4.6.4.3a once per 7 days on the OPERABLE train until the inoperable train is restored to OPERABLE status.
With no OPERABLE Hydrogen Ignitor in one containment region, restore one hydrogen ignitor in the affected containment region to OPERABLE status within 7 days, OR be in HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
Statement I
______.m.__.__...
m.
1 Replacement paragraphs for the Bases section.
3/4.6.4.3 Hydronen innition System (HIS)
BACKGROUND The HIS reduces the potential for breach of primary containment due to a hydrogen oxygen reaction in post accident environments. The HIS is required by 10 CFR 50.44, " Standards for Combustible Gas Control Systems in Light-Water-Cooled Reactors" (Ref.1). and Appendix A, GDC 41, " Containment Atmosphere Cleanup" (Ref. 2), to reduce the hydrogen concentration in the primary containment following a degraded core accident. The HIS must be capable of handling an amount of hydrogen equivalent to that generated from a metal water reaction involving 75% of the fuel cladding surrounding the active fuel region (excluding the plenum j
volume).
10 CFR 50.44 (Ref.1) requires units with ice condenser containments to install suitable hydrogen control systems that would accommodate an amount of hydrogen equivalent to that generated from the reaction of 75% of the fuel cladding with water. The HIS provides this required capability. This requirement was placed on ice condenser units because of their small containment volume and low design pressure (compared with pressurized water reactor dry containments).
Calculations indicate that if hydrogen equivalent to that generated from the reaction of 75% of the fuel cladding with water were to collect in the primary containment, the resulting hydrogen i
concentration would be far above the lower flammability limit such that, ifignited from a random l
ignition source, the resulting hydrogen burn would seriously challenge the containment and safety systems in the containment.
The HIS is based on the concept of controlled ignition using thermal ignitors, designed to be capable of functioning in a post accident environment, seismically supported, and capable of actuation from the control room. A total of 70 ignitors are distributed throughout the various regions of containment in which hydrogen could be released or to which it could flow in significant quantities. The ignitors are arranged in two independent trains such that each containment region has at least two ignitors, one from each train, controlled and powered redundantly so that ignition would occur in each region even if one train failed to energize.
When the HIS is initiated, the ignitor elements are energized and heat up to a surface temperature
> 1700 F. At this temperature, they ignite the hydrogen gas that is present in the airspace in the vicinity of the ignitor. The HIS depends on the dispersed location of the ignitors so that local pockets of hydrogen at increased concentrations would burn before reaching a hydrogen concentration significantly higher than the lower flammability limit. Hydrogen ignition in the
]
vicinity of the ignitors is assumed to occur when the local hydrogen concentration reaches 8.5 l
volume percent (v/o) and results in 100% of the hydrogen present being consumed.
l
-}.
APPLICABLE SAFETY ANALYSES The HIS causes hydrogen in containment to burn in a controlled manner as it accumulates l
following a degraded core accident (Ref. 3).
Burning occurs at the lower flammability j
concentration, where the resulting temperatures and pressures are relatively benign. Without the system, hydrogen could build up to higher concentrations that could result in a violent reaction if l
igmted by a random ignition source after such a buildup.
The hydrogen ignitors are not included for mitigation of a Design Basis Accident (D3A) because an amount of hydrogen equivalent to that generated from the reaction of 75% of the fuel cladding with water is far in excess of the hydrogen calculated for the limiting DBA loss of coolant l
accident (LOCA). The hydrogen concentration resulting from a DBA can be maintained less than l
the flammability limit using the hydrogen recombiners. The hydrogen ignitors, however, have l
been shown by probabilistic risk analysis to be a significant contributor to limiting the severity of l
accident sequences that are commonly found to dominate risk for units with ice condenser containments. As such, the hydrogen ignitors are considered to be risk significant in accordance t
l with the NRC Policy Statement.
Lco l
l Two HIS trains must be OPERABLE with power from two independent, safety related power I
supplies.
An OPERABLE HIS train consists of 34 of 35 ignitors energized on the train.
Operation with at least one HIS train ensures that the hydrogen in containment can be burned in a controlled manner. Unavailability of both HIS trains could lead to hydrogen buildup to higher concentrations, which could result in a violent reaction ifignited. The tw could take place fast enough to lead to high temperatures and overpressurization of contamment and, as a result, breach containment or cause containment leakage rates above those assumed in the safety analyses. Damage to safety related equipment located in containment could also occur.
Requiring OPERABILITY in MODES I and 2 for the HIS ensure its immediate availability after safety injection and scram actuated on a LOCA initiation. In the post accident environment, the two HIS subsystems are required to control the hydrogen concentration within containment to near its flammability limit of 4.1 v/o assuming a worst case single failure This prevents l
overpressurization of containment and damage to safety related equipment and instruments In MODES 3 and 4 both the hydrogen production rate and total hydrogen production after a LOCA would be significantly less than that calculated for the DBA LOCA. Also, because of the limited time in these MODES, the probability of an accident requiring the HIS is low.
i
- In MODES 5 and 6, the probability and consequences of a LOCA are reduced due to the pressure and temperature limitations'of these MODES.
Therefore, the HIS is not required to be OPERABLE in MODES 3,4, 5 and 6.
ACTIONS One Train Inocerable. Action a. and b.
' With one HIS train inoperable, the inoperable train must restored to OPERABLE status within 7 days or the OPERABLE train must be verified OPERABLE frequently by performance of SR 4.6.4.3a. The 7 day Completion Time is based on the low probability of the occurrence of a degraded core event that would generate hydrogen in amounts equivalent to a metal water reaction of 75% of the core cladding, the length of time after the event that operator action would be required to prevent hydrogen acce.salatior U n exceeding this limit, and the low probability of failure of the OFERABLE HIS train. Th Alternative Required Action b, by frequent surveillances, provides assurance that the OPERABLE train continues to be OPERABLE.
Both trains in One Containment Region Inoperable This condition is defined as one containment region with no OPERABLE hydrogen ignitor. (No Train A or Train B ignitor operable at the same containment location) Thus, while in this condition, or in this condition and the above described condition simultaneously, there would always 1,c ignition capability in the adjacent containment regions that would provide redundant capability by flame propagation to the region with no OPERABLE ignitors.
i This action calls for the restoration of one hydrogen ignitor in each region to OPERABLE status within 7 days. The 7 day Completion Time is based on the same reasons given undra th: above actic.i for one train inoperable.
Inability To Restore At Least One Hydrogen Ignitor To Operable Status Within the Action Time The unit must be placed in a MODE in which the LCO does not apply if the HIS subsystems cannot be restored to OPERABLE status wLhin the associated Completion Time. This is done by placing the unit in at least MODE 3, HOT STANDBY, within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. The r2cwed completion time of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> is reasonable, based on operating experience, to reach MODE 3 from full power i
conditions in an orderly manner and withott challenging plant systems.
I i
i 1.
J l
l SURVEILLANCE REOUIREMENTS (SR)
SR 4.6.4.3a This SR confirms that > 34 of 35 hydrogen ignitors can be successfully energized in each train.
The ignitors are simple resistance elements.
Therefore, energizing provides assurance of OPERABILITY. The allowance of one inoperable hydrogen ignitor is acceptable because, although one inoperable hydrogen ignitor in a region would compromise redundancy in that region, the containment regions are interconnected so that ignition in one region would cause burning to progress to the others (i.e., there is overlap in each hydrogen ignitor's effectiveness between regions). The Frequency of 92 days has been shown to be acceptable through operating experience.
SR 4.6.4.3b This SR confirms that the two inoperable hydrogen ignitors allowed by SR 4.6.4.3a (i.e., one in each train) are not in the same containmen region. The Frequency of 92 days is acceptable based on the Frequency of SR 4.6.4.3a, which provides the information for performing this SR.
SR 4.6.4.3c A more detailed functional test is performed every 18 months a verify system 0;'ERABILITY..
All ignitors, including normally inaccessible ignitors, are isudiy checked for a glow to verify that they are energized. Additionally, the surface temperature of each ignitor is measured to be 21700 F to demonstrate that a temperature sufficient for ignition is achieved. The is month Frequency is based on the need to perform this Surveillarice under the conditions that apply during a plant outage and the potential for an unplanned trans.'ent if the Surveillance were performed with the reactor at power. Operating experience has shown that these components usually pass the SR when performed at the 18 month Frequency, which is based on the refueling cycle. Therefore, the Frequency was concluded to be acceptable from a reliability standpoint.
REFERENCES 1.
2.
10 CFR 50, Appendix A, GDC 41.
3.
FSAR, Section 6.2.
4.
An Analysis of Hydrogen Control Measures at McGuire Nuclear Station, as Revised by Revision 9 to be Applicable to Catawba Nuclear Station.
-2.
A-a m
l 4
g e
j i
l l
i I
l ATTACIIMENT S l
1 REPRINTED TS PAGES I
f
(
I l
l i
-J 4
e i
i i
d l
d e
SENT BY: DUKE POWER COMPANY
- 4-1-96 ; 9
- 74AM ;
7043824545*
80383?P191;# 2 G.0NTAINNENTSYSTEMS HYDRDGEN IGNITION SYSTEM LIMITING CONDITION FOR OPERATION 3.6.4.3 Both trains of the Hydrogen Ignition System shall be OPERABLE.
l APPLICABILITY: HODES 1 and 2.
ACTION:
a With one train of the Hydrogen Ignition; System inoperable:
a.
Restore the inoperable train to OPERABLE status within 7 days, OR b.
Perform surveillance requirement 4.6.4.3a once per 7 days on the OPERABLE train until the inoperable train is restored to OPERABLE status.
With no OPERABLE Hydrogen Ignitor in one containment region, restore one hydrogen ignitor in the affected containment region to OPERABLE status within 7 Gays, OR be in HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
SURVEILLANCE REOUIREMENTS 4.6.4.3 Each train of the Hydrogen Ignition System shall be demonstrated OPERABLE Once per 92 days by energizing the supply breakers and verifying that a.
at least 34 of 35 ignitors are energized.
b.
Once per 92 days, verify at least one hydrogen ignitor is OPERABLE in each containment region.
Once per 18 months by verifying the temperature of each ignitor is a c.
minimum of 1700*F.
1 CATAWBA - UNITS 1 & 2 3/4 6-40 Amendment No.
Unit 1 Amendment No.
Unit 2
SENT BY' DUKE POCER COMPANY
- 4-1-90 ; 9:15AM :
7043824545*
8038313191:# 3 CONTAINMENT SYSTEME BASES 3/4.6.2 DEPRESSURIZATION AND COOLING SYSTEMS l
The OPERABILITY of the Containment Spray System ensures that containment depressurization and cooling capability will be available in the event of a LOCA.
The pressure reduction and resultant lower containment leakage rate are consistent with the assumptions used in the safety analyses. However, the i
Containment Spray System also provides a mechanism for removing iodine from the containment atmosphere, and therefore the time requirements for restoring an inoperable Spray System to OPERABLE status have been maintained consistent with those assigned other inoperable ESF eqdipment.
3/4.6.3 CONTAINMENT ISOLATION VALVES The OPERABILITY of the containment isolation valves ensures that the containment atmosphere will be isolated from the outside environment in the i
event of a release of radioactive material to the containment atmosphere or
{
i pressurization of the containment and is consistent with the requirements of GDC 54 through 57 of Appendix A to 10 'CFR Part 50.
Containment isolation within the time limits specified for those isolation valves designed to close automatically ensures that the release of radioactive material to the environ-t ment will be consistent with the assumptions used in the analyses for a LOCA.
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 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 consistent with the recommendations of Regulator Concentrations Following a LOCA,{ March 1971. Guide 1.7 " Control of Combustible Gas 1/4.6.4.3 Hydrogen Ionition Svetem (HIS)
BACKGROUND The HIS reduces the potential for breach of primary containment due to a hydrogen oxygen reaction in post accident environments.
The HIS is required by 10 CFR 50.44, " Standards for Combustible Gas Control Systems in Light-Water-Cooled Reactors" (Ref.1). and Appendix A, GDC 41, " Containment Atmosphere Cleanup" (Ref. 2), to reduce the hydrogen concentration in the primary containment following a degraded core accident. The HIS must be capable of handling an amount of hydrogen equivalent to that generated from a metal water reaction involving 75% of the fuel cladding surrounding the active fuel region (excluding the plenum volume).
\\
CATAWBA - UNITS 1 & 2 8 3/4 6-4 Amendment No.
Unit 1 i
Amendment No.
Unit 2 s
w w
ww a
w
--ww r
SENT BY: DUKE POWER C0KPANY t 4-1-98 3 9 15AM i 7043824545*
8038313191:# 4 k'
j i
J CONTAINMENT SYSTEMS 4
BASES 3/4.6.4.3 Hydrocen Innition System (HIS) (Continued)
)
10 CFR 50.44 (Ref.1) requires units with ice condenser containments to install suitable hydrogen control systems that would accommodate an amount of 4
}
hydrogen equivalent to that generatad from the reaction of 75% of the fuel cladding with water.
The HIS provides this required capability. This requirement was placed on ice condenser units because cf their small containment volume and low design pressure (compared with pressurized water reactor dry containments). Calculations indicate that if hydrogen equivalent j
to that generated from the reaction of 75% of the fuel cladding with water were to collect in the primary containment, the resulting hydrogen concentration would be far above the lower flammability limit such that, if j
ignited from a random ignition source, the resulting hydrogen burn would j
seriously challenge the containment and safety systems in the containment.
2 i
The HIS is based on the concept of controlled ignition using thermal ignitors, j
designed to be capable of functioning in a post accident environment.
seismically supported, and capable of actuation from the control room. A i
total of 70 ignitors are distributed throughout the various regions of
(
containment in which hydrogen could be released or to which it could flow in significant quantities.
The ignitors are arranged in two independent trains such that each containment region has at least two ignitors, one from each train, controlled and powered redundantly so that ignition wculd occur in each j
region even if one train failed to energize.
J When the HIS is initiated, the ignitor elements are energized and heat up to a surface temperature > 1700 F.
At this temperature, they ignite the hydrogen j
gas that is present Tn the airspace in the vicinity of the ignitor.
The HIS depends on the dispersed location of the ignitors so that local pockets of S
hydrogen at increased concentrations would burn before reaching a hydrogen concentration significantly higher than the lower flammability limit.
Hydrogen ignition in the vicinity of the ignitors is assumed to occur when the i
local hydrogen concentration reaches 8.5 volume percent (v/o) and results in 100% of the hydrogen present being consumed.
i APPLICABLE SAFETY ANALYSES The HIS causes hydrogen in containment to burn in a controlled manner as it accumulates following a degraded core accident (Ref. 3).
Burning occurs at the lower flansnability concentration, where the resulting temperatures and i
pressures are relatively benign. Without the system, hydrogen could build up l
to higher concentrations that could result in a violent reaction if ignited by j
a random ignition source after such a buildup.
CATAWBA - UNITS I & 2 8 3/4 6-4a Amendment No.
Unit 1 Amendment No.
Unit 2
- - - - - - - - " ~ - ~ ~ ~~
~~~^^^^^~~'i SENT BY: DUKE PO't:ER COMPANY
- 4-1-95 ; 9
- 16AM ;
7043824545*
8038313191*# 5
?
CONTAINMENT SYSTEMS BASES 3/4.6.4.3 Hydroaen fanition System (HIS) (Continued)
The hydrogen i Accident (DBA)gnitors are not included for mitigation of a Design Basisbecau the reaction of 75% of the fuel cladding with water is far in excess of the hydrogen calculated for the limiting DBA loss of coolant accident (LOCA).
The hydrogen concentration resulting from a DBA can be maintained less than the fismaability limit using the hydrogen recombiners. The hydrogen ignitors, however, have been shown by probabilistic risk analysis to be a significant contributor to limiting the severity of accident sequences that are commonly found to dominate risk for units with ice condenser containments.
As such, the hydrogen ignitors are considered to be risk significant in accordance with the NRC Policy Statement.
LG.Q Two HIS trains must be OPERABLE with power from two independent, safety related power supplies.
An OPERABLE HIS train consists of 34 of 35 ignitors energized on the train.
Operation with at least one HIS train ensures that the hydrogen in containment can be burned in a controlled manner. Unavailability of both HIS trains could lead to hydrogen buildup to higher concentrations, which could result in a violent reaction if ignited.
The reaction could take place fast enough to lead to high temperatures and overpressurization of containment and, as a result, breach containment or cause containment leakage rates above those assumed in the safety analyses. Damage to safety related equipment located in containment could also occur.
Requiring OPERABILITY in NODES 1 and 2 for the HIS ensure its immediate availability after safety injection and scram actuated on a LOCA initiation.
In the post accident environment, the two HIS subsystems are required to control the hydrogen concentration within containment to near its flammability limit of 4.1 v/o assuming a worst case single failure. This prevents overpressurization of containment and damage to safety related equipment and instruments
{
In MODES 3 and 4 both the hydrogen production rate and total hydrogen production after a LOCA would be significantly less than that calculated for the DBA LOCA. Also, because of the limited time in these MODES, the probability of an accident requiring the HIS is low.
In MODES 5 and 6, the probability and consequences of a L are reduced due to the pressure and temperature limitations of these MODES. Therefore, the 1115 is not required to be OPERABLE in MODES 3, 4, 5 and 6.
CATAWBA - UNITS 1 & 2 B 3/4 6-4b Amendment No.
Unit 1 Amendment No.
Unit 2
l SENT BY: DUKE POWER COMPANY
- 4-1-90 ; 9:17AM :
7043824545-*
B038313191:# 6 l :
j l
CONTAINMENT SYSTEMS BASES 3/4.6.4.3 Hydronen Ionition S_ystem (HIS1 (Continued)
ACTIONS One Train Inonerable Action a. and b.
With one HIS train inoperable, the inoperable train must restored to OPERABLE l
status within 7 days or the OPERABLE train must be verified OPERABLE frequently by performance of SR 4.6.4.3a.
The 7 day Completion Time is based on the low probability of the occurrence of a degraded core event that would generate hydrogen in amounts equivalent to a metal water reaction of 75% of the core cladding, the length of time after the event that operator action would be required to prevent hydrogen accumulation from exceeding this limit, and the low probability of failure of the OPERABLE HIS train. The Alternative Required Action b, by frequent surveillances, provides assurance that the OPERABLE train continues to be OPERABLE.
l Both trains in One Containment Reoion Inocerable This cc,ndition is one containment region with no OPERABLE hydrogen ignitor.
(No Train A or Train B ignitor operable at the same containment location)
Thus, while in this condition B, or in this condition and the above condition simultaneously, there would always be ignition capability in the adjacent containment regions that would provide redundant capability by flame propagation to the region with no OPERABLE ignitors.
This action calls for the restoration of one hydrogen ignitor in each region i
to OPERABLE status within 7 days. The 7 day Completion Time is based on the same reasons given under the above action for one train inoperable.
l Inability To Restore At least One Hydrocen Ioniter To Operable Status Within t
the Action Time The unit must be placed in a MODE in which the LCO does not apply if the HIS subsystems) cannot be restored to OPERABLE status within the associated l
Completion Time.
This is done by placing the unit in at least MODE 3 within 6 i
hours. The allowed Completion Time of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> is reasonable, based on operating experien:c, to reach MODE 3 from full power conditions in an ordetiy manner and without challenging plant systems.
SURVEILLANCE REQUIREhENTS (SR)
SR 4.6.4.3a l
This SR confirms that t 34 of 35 hydrogen ignitors can be successfully energized in each train. The ignitors are simple resistance elements.
I 1
CATAWBA - UNITS 1 & 2 B 3/4 6-4c Amendment No.
(Unit 1) l Arr.endment No.
(Unit 2) 4 l
SENT BY: DUKE POWER COMPANY
- 4-1-95 i 9:,17AM i 7043824545*
8038313191:# 7 s
CONTAINMENT SYSTEMS BASES 3/4.6.4.3 Hydrocen Ionition System (HIS1 (Continued)
Therefore, energizing provides assurance of OPERABILITY, The allowance of one inoperable hydrogen ignitor is acceptable because, although one inoperable hydrogen ignitor in a region would compromise redundancy in that region, the containment regions are interconnected so that ignition in one region would cause burning to hydrogen ignitor' progress to the others (i.e., there is overlap in each s effectiveness between regions). The Frequency of 92 days has been shown to be acceptable through operating experience.
SR 4.6.4.3b This SR confirms that the two inoperable hydrogen ignitors allowed by SR 4.6.4.3a (i.e., one in each train) are not in the same containment region.
The Frequency of 92 days is acceptable based on the Fre which provides the information for performing this SR. quency of SR 4.6.4.3a, SR 4.6.4.3c A more detailed functional test is performed every 18 months to verify system OPERABILITY.
Each glow plug is visually examined to ensure that it is clean and that the electrical circuitry is energized.
All ignitors (glow plugs),
including normally inaccessible ignitors, are visually checked for a glow to verify that they are energized.
Additionally, the surface temperature of each glow plug is measured to be m1700 F to demonstrate that a temperature sufficient for ignition is achieved. The 18 month Frequency is based on the need to perform this Surveillance under the conditions that apply during a plant outage and the potential for an unplanned transient if the Surveillance were performed with the reactor at power. Operating experience has shown that these con.ponents usually pass the SR when performed at the 18 month Frequency, which is be. sed on the refueling cycle.
Therefore, the frequency was concluded to be acceptable from a reliability standpoint.
REFERENCES 1.
10 CFR S0.44.
2.
10 CFR 50, Appendix A, GDC 41.
3.
FSAR, Section 6.2.
4.
An Analysis of Hydro en Control Measures at McGuire Nuclear Station, as Revised by Revision to be Applicable to Catawba Nuclear Station.
CATAWBA - UNITS 1 & 2 B 3/4 6-4d Amendment No.
Unit 1 Amendment No.
Unit 2
_ -