ML20205K317
| ML20205K317 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 02/21/1986 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML20205K316 | List: |
| References | |
| 1325K, NUDOCS 8602270298 | |
| Download: ML20205K317 (10) | |
Text
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ATTACMENT 1 P_Ro&9ED R ZION APPENDII A TECHNICAL SPL'CIFICATION CHANCES TO SECTIONS 3.9 AND 4.9 l CONTAINMENT ISOLATION i
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Table of Contents (Continued)
SURVEILLANCE LIMITING CONDITION FOR OPERATIDN REQUIREMENT PAGE 3.7 Steam Generator Emergency Heat Removal 4.7 156 3.7.1 Steam Generator Safety Valves 4.7.1 156 3.7.2 Auxiliary Feedwater Pump System 4.7.2 158 3.7.3 Auxiliary Feedwater Supply System 4.7.3 159a Bases 3.8 Emergency Core Cooling and Core Cooling Support 4.8 164 3.8.1 Centrifugal Charging Pump System
- 4.8.1 164 3.8.2 Safety Injection Pump System 4.8.2 168 3.8.3 Residual Heat Removal Pump System 4.8.3 170 3.8.4 System Testing of Centrifugal Charging, Safety 4.8.4 173 Injection, and Residual Heat Removal Pump Systems 3.8.5 Accumulator System 4.8.5 174 3.8.6 Component Cooling System 4.8.6 175 3.8.7 Service Water System 4.8.1 178 3.8.8 Hydrogen Control Systems 4.8.8 180 3.8.9 Equipment for Evaluating Post LOCA 4.8.9 184 Bases 3.9 Containment Isolation Systems 4.9 197 3.9.1 Isolation Valve Seal Water System 4.9.1 197 3.9.2 Penetration Pressurization Systems 4.9.2 198 3.9.3 Containment Isolation Valvas 4.9.3 199 3.9.4 Main Steam Isolation Valves and 8ypasses 4.9.4 200 3.9.5 Containment Integrity 4.9.5 201 3.9.6 Containment Ventilation System 4.9.6 202a 1 Bases 3.10 Containment Structural Integrity 4.10 212 3.10.1 Containment Leakage Rate Testing 4.10.1 212 3.10.2 Containment Tendon Testing ' 4.10.2 215 3.10.3 End Anchorages and Adjacent Concrete Surfaces Inspection 4.10.3 217 3.10.4 Containment Liner Inspection 4.10.4 218 3.10.5 Containment Pressure 4.10.5 219 3.10.6 Centainment Temperature 4.10.6 219 Bases 3.11 Radioactive Liquids 4.11 222 Bases 3.12 Radioactive Gases . 4.12 230 Bases 111 05480
LIMITING CONDITION FOR OPERATION SURVEILLANCE REQUIREMENT 3.9.6 CONTAINMENT VENTILATION SYSTEM 4.9.6 CONTAINMENT VENTILATION SYSTEM Ao The purge supply and exhaust isolation valves A. 1. The position of the containment purge shall be limited to a maximum opening of 50 supply and exhaust isolation valves degrees. shall be determined at the beginning of purge or venting operations and at B. The containment vent line shall be isolated least once per week while venting or whenever a containment purge line is open. purging.
- 2. When purge isolation valve position is APPLICABILITY: Modes 1, 2, 3, 4, and 7 being controlled by regulating the air pressure to the valve operator, the air ACTION: a. With the purge supply or exhaust pressure shall be measured at the isolation valve (s) open greater than 50 beginning of the purge operation and degrees, return the valve (s) to an daily while purging, acceptable position within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or terminate purge operations and close and 3. The cumulative gaseous radioactive deactivate at least one in-series purge effluent release shall be determined isolation valve or be in at least HOT once per month for the purpose of SHUT 00WN within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in verifying compliance with the gaseous COLD SHUTDOWN within the following 30 effluent release limits.
hours.
- 4. At least once per 18 months valves
- b. With the containment vent isolation RV0001, RV0002, RV0003, RV0004, RV0005 valves and purge isolation valves open and RV0006 shall be closed manually simultaneously 1solate one of the flow from the control room and the closing paths within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or be in at least HOT time measured. Performance will be SHUTDOWN within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in acceptable if the valves close within COLD SHUTDOWN within the following 30 seven seconds.
hours.
05480/09290 202a n??qA
B_ asis: 3.9
- 1. The isolation valve seal water system 2. The function of the containment penetration interposes water inside the penetrating line and weld channel pressurization system is to .
between two isolation points located outside prevent leakage of containment air through a containment. The water is introduced at a penetrations and liner welds under all pressure of at least 50 psig which is conditions by supplying air above the slightly higher than the containment post containment post accident pressure to the accident pressure. (1) The possibility of positive pressure zones incorporated in the leakage from a containment or reactor penetration and weld channel design (2).
coolant system past the first isolation point is thus prevented by assuring that if Flow sensing devices are connected to each leakage does exist, it will be from the seal quadrant header of a pressurization system water system into the containment. and to the main header. Pressure sensors are also connected to each quadrant header.
The system includes one 160 gallon seal Flow is recorded from each quadrant and the water tank for each unit which is capable of main header, and is alarmed in control supplying the total requirements of the room. Low pressure is also alarmed. A leak system. The tank is filled with water from would be expected to build up slowly and the primary make-up water system and would therefore be noted before leakage pressurized with nitrogen from the nitrogen became excessive. (2) supply header. To ensure an adequate supply of seal water a back-up source of make-up 3. In the unlikely event of loss of coolant water for the tank is provided by a accident the containment atmosphere will be connection to the service water system. The isolated from the environment by the use of high pressure nitrogen supply used to isolation valves and other barriers for all maintain pressure in the seal water tank pipelines which penetrate the containment does not require any external power source unless such lines are required for service to maintain the required driving pressure. during the accident. All lines for which isolation is required are provided with two The low limit of 70 gallons is based upon barriers so that no single failure will having an initial supply of water prior to prevent isolation. No manual operation is make-up. The low limit of 68 psig is based required for immediate isolation. Automatic on a pressure of 50 psig between the isolation is initiated by safety injection isolation valves. Low tank level and . signal. (3) pressure are alarmed in the control room.
In lines where two automatic isolation valves are required, each valve operator will be actuated by an independent signal.
Each valve operator is also supplied from a separate emergency supply. (3) 0807t/0B08t 209
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Bas:s 3.9 (Continued)
- 4. The main steam trip valves serve to limit an initial 10% AK/K subcritical reactor -
cxcessive Reactor Coolant System cooldown condition precludes criticality because the rate and resultant reactivity insertion reactor would be substantially subcritical following a main steam line break accident. even if all control rods were completely Their ability to close fully shall be withdrawn. Positive reactivity changes by v rified at each refueling outage. A boron dilution may be required or small closure time of 5 sec. was selected since fluctuations may occur during preparation this is the closure time assumed in the for, recovery from, or during refueling, but safety evaluation. (4) The partial valve maintaining the reactor subcritical by at stroke test will take place to verify the least 10% AK/K precludes criticality under freedom of the valve disc to function as any circumstances. (5) rcquired. A limit switch in the test circuit prevents the valve disc from 6. It is estimated that approximately 2000 hrs cntering the flow stream and slamming the of purging per 365 days will be required in valve shut during in-service testing, order to maintain the containment atmosphere at less than 100 MPC and thereby reducing The main steam bypass valves and lines are personnel radiation exposure levels. The'50 sized so that the reactor will remain degree' limit on valve position was agreed to subcritical after reactor trip for a by the NRC as a very conservative spurious opening of a bypass valve or a interpretation of CYGNA Energy Services d:uble-ended rupture of a bypass line. final report #83003/1/F and /2/F.
- 5. Ccntainment integrity requirements are based The purge isolation valves are supplied by en reactor coolant system conditions. Cold the penetration pressurization system.
shutdown assures that no steam will be fermed and hence there would be no pressure buildup in the containment if the reactor coolant system ruptures.
Th2 shutdown conditions of a reactor are selected based on the type of activities (1) 'FSAR Section 6.6.5 that are being carried out. When a reactor (2) FSAR Section 6.6.6 h ad is not to be removed, the specified (3) FSAR Section 6.6.1 cold shutdown margin of 1% AK/K precludes (4) FSAR Section 14.2.5 critically under any occurrence. During (5) FSAR Table 3.2.1-1 refueling a reactor is subcritical by 10%
AK/K. This precludes criticality under any circumstances even though fuel is being moved or control rods withdrawn. Positive reactivity addition by rod motion from an 05480/09290 210 0229A
Basis:
4.9 The isolation valve seal water system and i
penetration pressurization systems are essentially static systems during normal ,
operation; abnormal condition within the -
systems are alarmed in the control room.
i The limiting conditions within the systems are checked monthly to determine longterm
' gradual degradation of system status. In -
addition, the penetration air compressors are load tested following maintenance to ~
ensure operability; and the headers are prassure checked following maintenance to ensure system integrity.
Periodic testing of containment isolation valves assures their continued operability.
More frequent instrument channel checks result in increased reliability. In addition, valve movement is timed to ensure proper closure times.
The main steam isolation valves are functionally tested on a more frequent interval to establish freedom of movement of the valve disc. ~-
0807t/0808t 211
ATTACHMENT 2 DESCRIPTION AND JUSTIFICATION OF PROPOSED AMENDMENT The proposed change will impose new Technical Specification restrictions on containment purge and vent operations. This change will create two new Technical Specification Sections 3.9.6 and 4.9.6. The major elements of these two new sections are enumerated below:
- 1. The purge supply and exhaust valves shall not be opened more than 50 degrees unless the reactor is in the cold shutdown or refueling modes.
The position of the valves must be verified during purge operations.
- 2. The containment purge valves shall not be open concurrently with the containment vent valves.
- 3. The stroke times of the purge and vent valves shall be measured every eighteen months. The limit shall be seven seconds.
- 4. A goal of 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> of purging per year has been established and documented in the bases.
DISCUSSION - ITEM #1 Reference (e) documented the results of the NRC's review of the analyses supplied by Commonwealth Edison Company. The intermediate purge valve position of 50 degrees was found to be acceptable. Section 5.0 stated;
...We find the information submitted demonstrated the ability of the purge and vent valves 1/2 AOV-RVOO1, 2, 3 and 4 to close from the intermediate 50' open position against a DBA/LOCA containment pressure rise...
Thus, the imposition of this new restriction has been thoroughly analyzed, reviewed, and has been found to be acceptable.
DISCUSSION - ITEM #2 This condition is a conservative restriction that simplifies the control of radioactive release paths and rates. This precludes the existence of multiple containment release paths.
p..
DISCUSSION - ITEM #3 This surveillance will ensure that the valves will close within an acceptable time period. The seven second closure time limit was addressed in reference (e) and was found to bound both the normal closure times and the eight second closure time which produced the highest calculated mechanical stresses.
In addition, the seven second closure time was shown to result in acceptable off-site doses per 10 CFR 100 in reference (f).
DISCUSSION - ITEM #4 The goal of 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> per year is based upon the need to limit the concentration of radioactive materials in the containment atmosphere to less than 100 times the maximum permissible concentration per 10 CFR 20. This will ensure personnel safety during any required containment entries. This goal will also help to prevent excessive purging during reactor operation.
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ATTACMMENT 3 EVALUATION OF SIGNIFICANT HAZARDS CONSIDERATION PROPOSED CHANCES TO ZION TECHNICAL SPECIFICATION APPENDII A - SECTION 3.9 CONTAINMENT ISOLATION DESCRIPTION OF AMENDMENT REQUEST An amendment to the Zion Facility Operating License is proposed to include restrictions on containment purge and vent operations. The purge valves will be limited to 50 degrees open and the vent valves will remain closed whenever the purge valves are open.
BACKGROUND 10 CFR 50.92 states that a proposed amendment will involve a no significant hazards consideration if the proposed amendment does not:
(1) Involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) Involve a significant reduction in a margin of safety.
In addition, the Commission has provided guidance in the practical applica-tion of these criteria by publishing eight examples in 48 FR 14870.
The discussion below addresses each of these three criteria and demonstrates that the proposed amendment involves a no significant hazards consideration.
BASIS FOR NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION Does the proposed amendment (1) Involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) Involve a significant reduction in a margin of safety?
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DISCUSSION - ITEM #1 The imposition of these restrictions results in more conservative operation than was previously allowed by the Zion Technical Specifications.
The 50 degree maximum opening limit results in more reliable containment isolation than a full open valve. Thus, the excessive release of radioactive material following a postulated LOCA is less likely with the valve opening limited to 50 degrees.
The addition of a closure time limit of 7 seconds is drastically more limiting than the previously allowed value of 60 seconds contained in Section 4.9.3. The valve-specific time limit greatly reduces the potential for excessive off-site releases of radioactive material following a postulated LOCA.
Thus, the potential consequences of any previously evaluated accidents have been reduced. In addition, the imposition of these tighter controls over the purge and veat operations does not affect the probability of any previously evaluated accident.
DISCUSSION - ITEM #2 As discussed above, the proposed amendment will impose tighter restrictions on purge and vent operations than the existing Technical Specifications. There have been no design changes as a result of this change. Thus, the imposition of limits on purge valve position and closure time will result in more conservative operation and will not create the possibility of a new or different kind of accident.
DISCUSSION - ITEM #3 The imposition of the more conservative limits on purge valve position and closure time will increase the margin of safety. As discussed above, these new restrictions will reduce the likelihood of an excessive release of radioactive materials following a postulated LOCA. Thus, the margin of safety will not be adversely affected.
Note that the proposed amendment meets and exceeds the example (ii) of the Commission guidance provided in 48 FR 14870.
(ii) A change that constitutes an additional limitation, restriction, or control not presently included in the Technical Specifications: for example, a more stringent surveillance requirement.
Therefore since the application for amendment satisfies the criteria specified in 10 CFR 50.92 and is similar to examples for which no significant hazards consideration exists, Commonwealth Edison Company has made a determination that the application involves no significant hazards consideration.
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