ML20052E801
| ML20052E801 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 05/06/1982 |
| From: | Withers B PORTLAND GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20052E785 | List: |
| References | |
| TAC-48390, NUDOCS 8205110433 | |
| Download: ML20052E801 (8) | |
Text
yo PORTLAND GENERAL ELECTRIC COMPANY EUGENE WATER & ELECTRIC BOARD AND PACIFIC POWER & LIGHT COMPANY TROJAN NUCLEAR PLANT Operating License NPF-1 Docket 50-344 License Change Application 86 This License Change Application requests modification of Technical Specifications 3/4.6.3 and 3/4.6.4 contained in Appendix A to Operating License NPF-1 to improve overall Containment integrity and improve the reliability of Containment atmosphere control systems.
PORTLAND GENERAL ELECTRIC COMPANY a
J By ~
B. D. Withers Vice President Nuclear Subscribed and sworn to before me this 6th day of May 1982.
OMyCommiss i +-b
- <bJ Notary Public of Oregon a f,. f [/[/N 9
8205110433 820506 PDR ADOCK 05000344 P
LCA 86
.1 Psga 1 of 7 LICENSE CHANGE APPLICATION 86 The proposed replacement pages to Appendix A of Facility Operating License NPF-1 are provided as Attachment 1.
A description of these changes follows:
1.
Page 3/4 6-16.
Surveillance Requirement 4.6.3.1.2.b has been changed to require that, in addition to Containment purge supply and exhaust valves, it be verified that hydrogen vent supply and exhaust valves actuate to their isolation positions upon receipt of a Containment Ventilation Isolation (CVI) signal.
Surveillance Requirement 4.6.3.1.2.c has been added to require' verification that Containment purge and hydrogen vent supply and exhaust valves actuate to their isolation positions upon receipt of a high radiation signal.
Surveillance Requirement 4.6.3.1.4 has been added to require that Containment purge supply and exhaust valves be verified inoperable (electric power or air supplies removed from their respective operators) every 31 days while in Operating Modes 1 through 4.
Surveillance Requirement 4.6.3.1.5 has been. added to require leak testing of Containment purge supply and exhaust valves during Modes 5 or 6 prior to entering Mode 4.
The Containment purge supply and exhaust valves shall also not be cycled af ter final leak testing prior to entering Mode 4.
Leakage rate acceptance criteria will be such that when the measured leakage rate is added to the leakage rates determined pursuant to Technical Specification 4.6.1.2.d for all other Type B and C penetrations, the combined leakage will be less than or equal
.60La.
The leakage rate for the Containment purge supply and exhaust valves shall also be compared to their previously measured leakage rate to determine excessive valve degradation.
2.
Page 3/4 6-18.
The eight hydrogen vent valves (M010005-through 10012) listed in Table 3.6-1 of Technical Specification 3/4.6.3 under the Containment Isolation section have been moved to the Containment Ventilation Isolation section on Page 3/4 6-20 of Table 3.6-1.
3.
Page 3/4 6-19.
In Table 3.6-1 of Technical Specification 3/4.6.3 under the Containment Isolation section, two Containment atwo-sphere sample supply line drain valves (SV-5642 and SV-5643) and one Containment atmosphere sample return line isolation valve (SV-5679) have been added.
4.
Page 3/4 6-20.
In Table 3.6-1 the eight hydrogen vent valves (M010005-10012) have been moved from the Containment Isolation section to the Containment Ventilation Isolation section.
Asterisks were added to the Containment purge and hydrogen vent supply and exhaust valve identification numbers to require that the Containment purge supply and exhaust valves be made inoperable (electric power or air supplies removed from'their respective
LCA 86 P2g2 2 ef 7 operators during Modes 1-4), and require that the hydrogen vent supply and exhaust valves be normally closed and opened only when and for the duration of time actually necessary. Editorial changes were also made to provide proper name identification of hydrogen vent supply and exhaust valves and Containment purge supply and exhaust valves.
5.
Page 3/4 6-24.
Footnotes were placed at the end of Table 3.6-1 to be utilized with the corresponding asterisks in Table 3.6-1 to require that the Containment purge supply and exhaust valves be made inoperable (electric power or air supplies removed from their respective operators) during Modes 1-4, and require the hydrogen vent supply and exhaust valves to be normally closed and opened only when and for the duration of time actually necessary.
6.
Page 3/4 6-30.
Surveillance Requirement 4.6.4.4.b has been changed so that the hydrogen mixing system flow rate verifica-tion value be 2500 cfm +10 percent instead of 2500 cfm.
7.
Page B 3/4 6-4.
Technical Specification Bases 3/4.6.3 has been changed to provide additional information on the revised operabil-ity and testing requirements for the Containment purge and hydro-gen vent supply and exhaust valves.
The following paragraphs have been added to the Technical Specification Bases 3/4.6.3:
"The Containment purge supply and exhaust valves are maintained shut with their power supplies removed dur-ing Operating Modes 1-4, since they have not been qualified under Design Basis Accident LOCA conditions.
Because the Plant is in an inherently safer condition with Containment ventilation valves shut, hydrogen vent i
supply and exhaust valves are normally shut and opened only when and for the duration of time actually neces-sary."
"The Containment purge supply exhaust valves have resil-ient seat material which may be subject to leakage past the seats. For this reason leak testing on these valves is performed prior to entering Mode 4 from Mode 5, pro-vided the purge valves had been cycled while in Modes 5 or 6."
REASON FOR CRANGE in response to NUREG-0737, " Clarification of TMI Action Plan Requirements",
PGE committed to the incorporation of a high radiation signal to provide automatic closure of hydrogen vent supply and exhaust valves. Prior to NUREG-0737, the high radiation signal only provided an automatic closure signal for the Containment purge supply and exhaust valves. The Contain-ment isolation signal (CIS) also provides an automatic closure signal for the Containment purge and hydrogen vent supply and exhaust valves. The high radiation signal now provides automatic closure of hydrogen vent
LCA 86 Page 3 of 7 supply and exhaust valves.
For this reason, Surveillance Requirement 4.6.3.1.2.b has been changed to provide an additional requirement to verify that hydrogen vent valves will actuate to their isolation positions upon receipt of a CVI signal. The high radiation signal, although not an Engineered Safety Features signal, provides input to the CVI logic circuitry. As requested by the NRC and in order to test the circuitry emanating f rom the Containment high radiation detector, Surveillance Requirement 4.6.3.1.2.c has been added to verify the Containment purge and hydrogen vent supply and exhaust valves actuate to their isolation positions upon receipt of a high radiation signal.
A design review, conducted in response to NUREG-0737, identified that condensation could accumulate in the low point of the Containment hydro-gen analysis Train B sample line and may prevent its proper operation. A solenoid-operated valve (SV-5642) has been added to the low point in the Train B sample line to allow periodic draining of this condensation.
Although the potential loop seal would not cause a blockage of the Train A sample line, it is suspected that moisture buildup could prevent the obtaining of representative iodine samples from the Containment atmo-sphere, since the Train A sample line is the shared sample piping for the Containrent Purge Radiation Monitoring System (PRM-1) and the new Post-Accident Sampling System to be added in response to NUREG-0737. Therefore, a solenoid-operated valve (SV-5643) has also been added to the low point in the Train A sample line to remove condensation for representative iodine sampling for the Containment atmosphere.
The new low point drain valves would allow periodic draining of any moisture buildup in the inlet sample line.
If the four existing sample solenoid valves (SV-5662, -$c 0,
-5669, and -5670) were lost, a Containment atmosphere sample could be taken through the new low point drain valves to each hydrogen analysis panel.
The Containment atmosphere sample return lines have a common isolation valve for both Trains A and B with an alternate path to the Containment Purge Exhaust System.
A solenoid-operated valve (SV-2679) has now been added to the return line to provide redundancy back into Containment.
Because of their respective locations, all three solenoid valves have become new Containment isolation valves located inside Containment.
The valves are normally closed and raceive a Channel A Containment Isolation Signal (CIS) which will override the hand-switch controls. The electri-cal power to the valves is provided from the Channel A bus in order to be consistent with other isolation valves located inside Containment.
i Table 3.6-1 of Technical Specification 3/4.6.3 has been changed to include solenoid valves SV-5642, -5643 and -5679 with an isolation time of 3 sec.
According to the valve manufacturer (Target Rock Corporation),
a 3-sec closure time is a reasonable maximum time before suspecting a problem or malfunction of the valve.
f In response to an earlier NRC letter, the Trojan plant committed to i
maintaining the 54-in. Containment purge valves closed during Modes 1 l
l l
l l
LCA 86 Pega 4 of 7 through 4.
This was due to the purge valves not being qualified to shut during the dynamic loads of a Design Basis-Loss-of-Coolant Accident (DBA-LOCA). To provide assurance that the purge valves will remain closed during Plant operation to preclude the release of radioactivity to the environment should a LOCA occur, the NRC has requested that PGE maintain Containment purge supply and exhaust valves locked closed during Modes 1 through 4.
Because the purge valves cannot be physically locked closed, PGE has agreed to remove the electric power or air supplies to the purge valve operators during Modes 1 through 4.
An additional surveillance requirement has been added to verify every 31 days that the power supplies to the purge valves have been removed.
The NRC feels the Trojan plant would be inherently safer with closed hydrogen vent valves rather than open valves which require valve action to provide Containment integrity, even though PGE provided information to the NRC to justify venting without limitations through the 8-in.
hydrogen vent system during power operation.
PGE and the NRC have concluded that utilization of the hydrogen vent valves during power operations should cane place only when and for the duration of time actually necessary.
As a result of numerous reports on the unsatisfactory performance of resilient seats for isolation valves in Containment purge and vent lines, the NRC has proposed that in addition to the current requirements of 10 CFR 50, Appendix J, additional leakage testing should be conducted on Containment purge and hydrogen vent supply and exhaust valves. The purpose of these additional tests is to identify excessive degradation of the resilient seats of the ventilation isolation valves which are subject to either environmental extremes or frequent usage. The present requirements in Appendix J for performing the local leak rate testing may be modified in the future depending upon the results of the additional proposed leakage tests.
Because the Containment purge valves will remain closed during Modes 1 through 4, it is not necessary to test them every 6 months during Plant operation. To ensure the purge valves maintain their leakage integrity during power operation, they will be leak tested prior to entering Mode 4 from a cold shutdown condition, provided they had been cycled while in Modes 5 or 6.
Purge valves will also not be cycled after leak testing and prior to entering Mode 4.
Appendix J 1eak test require-ments will also continue in effect, thus assuring leak testing of the purge valves at least every refueling outage.
Although the hydrogen vent valves also have resilient seats, they have demonstrated a very small potential for leakage during Appendix J local leak rate tests conducted during the previous 6 years.
It is intended to replace the hydrogen vent valves with valves with non-resilient seats during the 1983 refueling outage.
For this reason, Technical Specifica-tion changes will not be requested for leak testing of the hydrogen vent valves. Until the hydrogen vent valves are replaced, PGE has committed to maintain the hydrogen vent supply valves shut with their power sup-plies removed during Modes 1 through 4.
PGE has also committed to leak test the hydrogen vent exhaust valves every 6 months until they are replaced. Appendix J 1eak test requirements will also continue to be observed.
~
LCA 86 Page 5 of 7 Technical Specification 4.6.4.4.b has been changed by revising the Containment Hydrogen Mixing Fan (VC 220A and B) 18-month flow verifica-tion value from "at least 2500 cfm" to "2500 cfm +10 %".
This revision is to account for the error associated with the state-of-the-art method of verifying air flow rate. The Pitot Traverse flow verification method has an accepted f)0 percent error range, and to confidently verify an "at least 2500 cfm" flow rate so that compliance with the Technical Specifications is assured, it would be necessary to set the flow to at least 2750 cfm.
By setting the fans at 2750 cfm, the air flow could still be assured of being at least 2500 cfm even if the measurement was 10 percent high in error. This action, however, would place the fans outside of their maximum motor current ratings for the Design Basis Accident air density conditions of 3.6 atmospheres, and would jeopardize their operability if the air flow measurement error was 10 percent low.
If the requirement were stated as "2500 cfm f30%", then this upper design limit could be avoided. Other air flow values in the Technical Specifica-tions implicitly assume this possible measurement error by specifying a certain value fJO percent. Changing the Hydrogen Mixing Fan's air flow rate to 2500 cfm f)0 percent will remain consistent with the other requirements of the Technical Specifications.
SAFETY ENVIRONMENTAL EVALUATION Summary of Change A summary of changes to the Technical Specifications is provided in the description of changes beginning on Page 1 of 1 of this LCA.
Effect on the Technical Specifications and Bases for the Technical Specifications The proposed Technical Specification changes which limit the operation of Containment purge and hydrogen vent supply and exhaust valves, require additional verification that Containment purge valves are inoperable, and which require additional testing of valve control circuitry and leakage rate only serve to improve overall Containment integrity. These changes will increase the margin of safety to the general public by reducing the possibility of radioactive releases to the environment.
The Technical Specification change to Surveillance Requirement 4.6.4.4.b, which allows for a hydrogen mixing system flow rate of 2500 cfm f30 percent, is consistent with similar air flow requirements elsewhere in the Technical Specifications since they already specify a certain valve f)0 percent. Even with the potential 10 percent reduction in air flow capacity which this Technical Specification change could imply, these fans could still completely recirculate the gross air volume of the dome i
every 3.7 hr.
Circulating 998,306 cubic feet of air this rapidly would provide more than adequate mixing to prevent conc,ntrations from reaching flammable proportions in localized area. This cocclusion is based on the following information:
LCA 86 Pcg2 6 cf 7 1.
Hydrogen diffuses readily into air, thus reducing the potential for stratification. This tendency is enhanced if the gas is released well below the ceiling or when the hydrogen is intro-duced as a high pressure jet of gas.
2.
Situations where higher local concentrations are possible, such as gradual leaks very near the ceiling, can be easily corrected by maintaining a slight air circulation.
In a Loss-of-Coolant Accident, more than 50 percent of the hydrogen production comes from zirconium - water reactions, core gamma, and radiolysis of sump halogens in the bottom of the Containment. The gas produced in this area will diffuse throughout the Containment atmosphere before it has a chance to concentrate in the dome. The balance of the hydrogen will be produced from zine reactions and aluminum corrosion throughout the Containment structure. The slow production rate from these sources could produce locally flammable concentrations if the gas is released very close to the ceiling; however, the slight circulation of air necessary to prevent such concentrations is easily provided by the mixing fans.
Table 3.6-1 of Technical Specifications 3/4.6.3 reflects the addition of two Containment atmosphere sample line drain valves and one sample line isolation valve. This addition has been incorporated in order to improve the reliability and operation of the existing Containment Hydrogen Analysis System and complies with the existing design criteria for the Containment isolation valves. The addition of the three sample line valves to Table 3.6-1 ensures maintenance of overall containment integrity and does not result in the reduction of any safety margins.
The Bases for the Technical Specifications are not changed with the exception of Bases 3/4.6.3, " Containment Isolation Valves", as described in the description of changes beginning on Page 1 of 1 of this LCA.
Technical Specification Bases 3/4.6.3 has been changed to provide explana-tion and justification for additional operability and testing require-ments for Containment purge and hydrogen vent supply and exhaust valves.
The Technical Specification and Bases changes proposed by this LCA do not increase the occurrence probability or consequences of different or i
previously analyzed accidents, nor do they reduce any margins of safety.
Effect on FSAR The FSAR is only affected by the addition of three Containment atmosphere sample line isolation valves. FSAR Section 6.2, Table 6.2-1, " Containment Isolation Barriers", and Figure 6.2-39 list each Containment penetration with associated isolation valves. The three new isolation valves need to be included in the table and figure. The proposed change is consistent with the design criteria and bases discussed in the FSAR for the Contain-ment isolation systems. The proposed change thus will not introduce any new accidents, nor will it affect the results or consequences of any previously analyzed transients. Therefore, no unreviewed safety question is involved.
LCA 86 Pagt 7 of 7 Environmental Effect t
The proposed changes do not affect the environmental analyses in the FSAR, the Environmental Report and/or the final Environmental Impact Sta te ment. No unreviewed environmental question exists, and there is no adverse effect on the environment due to the proposed changes.
BASIS FOR DETERMINATION OF AMENDMENT CLASS This License Change Application has been determined to result in a Class III amendment in accordance with the criteria of 10 CFR 170.22.
This change does not involve a significant hazards consideration.
t 4
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