ML20137X968
| ML20137X968 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 04/14/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20137X962 | List: |
| References | |
| NUDOCS 9704220268 | |
| Download: ML20137X968 (8) | |
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UNITED STATES g
j NUCLEAR REGULATORY COMMISSION t
WASHINGTON, D.C. soseMooi SAFETY EVALUATION BY'THE OFFICE OF NUCLEAR REACTOR REGULATION-RELATED TO AMENDMENT NO. 119 TO FACILITY OPERATING LICENSE NO. DPR-80 AND AMENDMENT NO. 117 TO FACILITY OPERATING LICENSE NO. DPR-82 PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT. UNITS 1 AND 2 DOCKtT WOS. 50-275 AND 50-323
1.0 INTRODUCTION
By application dated May 31, 1996, as supplemented by letter c'ated December 16, 1996, Pacific Gas-and Electric Company (or-the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos. DPR-80 and DPR-82) for the Diablo Canyon Nuclear Power Plant, Units 1 and 2.
The proposed changes revise the combined Technical Specifications (TS) for the Diablo Canyon Power Plant (DCPP) Unit Nos.- 1 and 2 to revise 23 TS surveillance requirements to support implementation of extended fuel cycles at DCPP Unit Nos. I and 2.
The specific TS changes proposed include those for 2 response time tests, 3 containment spray system tests, and 24 ventilation system tests. There are also administrative changes for six other TS to maintain consistency for TS that are not proposed for surveillance extension.
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The December 16, 1996, supplemental letter provided additional clarifying information and did not change the initial no significant hazards consideration determination published in'the Federal Reaister on October 7, 1996 (61 FR 52966).
2.0 BACKGROUND
The licensee conducted a feasibility-study for increasing the fuel cycle length from the current 18 months to 24 months for both units of DCPP.
The results of this study indicated that a 24-month fuel cycle is not only feasible but also is beneficial because of fewer refuelings, improved outage scheduling and reduced personnel exposure.
Therefore, the licensee decided to implement the extended 24-month fuel cycles at both units of the DCPP.
Current DCPP TS require that surveillance tests for some surveillances be performed at least once per refueling interval, or every 18 months.
Therefore, the surveillance test interval (STI) for these functional units have been identified by a notation "R" in an appropriate column of the current TS instrumentation tables. With the extended fuel cycle, the STI for these tests will be 24 months and will be identified by the notation "R24".
For other surveillance tests the months will be changed to indicate a 24-month fuel cycle or the words " REFUELING INTERVAL" will replace the current wording.
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3.0 EVALUATION Except for several editorial changes, most of the proposed changes extend the surveillance interval from 18 to 24 months for various surveillance tests. To i
i confirm that the effect on safety of extending surveillance intervals is insignificant, the licensee's submittal provided information on each of the i
proposed changes focusing on verifying that no time-dependent failure
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mechanisms exist, and no known mechanism exists that would'significantly j
degrade the performance of the device-in-question during normal plant j
operation over the extended maximum surveillance interval.
In the evaluation of each of the proposed changes, the licensee addressed
'various applicable factors including, (1) the safety function (s) of the i
component / system, (2) the impact of the STI change on safety, (3) impact on
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other.TSs (if any) which also stipulate performing similar tests during an j-operating cycle and/or during a refueling outage, (4) the operating, surveillance and maintenance histories and problems identified through these i.
histories in the past and the nature of corrective actions implemented,.and l
(5) related NRC generic communications and industry experience.
In their submittal,' the licensee stated that the request for the proposed 4
modifications in STIs is based on guidance provided by the staff in Generic 1
Letter (GL) 91-04, " Changes in Technical Specification Surveillance Intervals to Accommodate a 24-month Fuel Cycle" dated April 2, 1991.
GL 91-04 provides guidance on how licnesees should evaluate the effects of an extension to a 24-month surveillance interval on the safety of the plant.
The licensee performed a detailed engineering analysis of the affected systems and l
instrument-loops to establish the basis for a maximum 30 month (24 months + 25 j
percent additional surveillance frequency illowance) calibration frequency and to' verify that the surveillance interval. extensions have an insignificant i
effect on plant safety by verifying that the extended frequency of 4
surveillance would not invalidate any assumptions in the plant's licensing i
basis.
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3.1 Response Time Testina i
j 3.1.1 Proposed TS chanaes TS 4.3.1.2, Reactor Trip Instrumentation, surveillance requirements for the reactor trip system response time.
Revise surveillance frequency from 18 l
months to 24 months.
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TS 4.3.2.2, Engineered Safety Features Actuation System Instrumentation, surveillance requirements for engineered safety features response time.
Revise surveillance frequency from 18 months to 24 months.
3.1.2 Justification for the Chanae l
In accordance with the current TS, response time testing (RTT) of specific functions of the reactor trip system and engineered safety features actuation system is performed once every 18 months during each refueling outage using an
- overlapping series of tests of discrete block and device of the control loop
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!- i including the process sensor (transmitter), signal processing devices, j
actuation logic and the final actuation device (breakers, switches, relays, j-etc.). The response time obtained from testing of each discrete block / device of a control string is summed up and the sum is compared to the response time i
i assumed in the safety analysis for that control string.
The' proposed revision revises the RTT frequency from 18 months to the new outage frequency of 24 months.
The justification for this extension is based on the licensee's~
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review of.the surveillance and operating history and evaluation of other j
surveillance tests performed at DCPP for components subject to response time 4
testing.
The licensee stated that no response time problems related to i
equipment performance have occurred and no time-dependent failure history was i
evident for any component.
This supports the conclusion that the effect on safety of extending the surveillance interval is negligible. The staff has reviewed these proposed changes and based on the licensee's justification
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finds.the proposed changes acceptable.
3.2 Containment Sorav System 1
3.2.1 Proposed TS chanaes TS 3/4.3.2, " Engineered Safety Features Actuation System," Table 4.3.-2, Functional Unit 2.a, regarding manual containment spray initiation.
Revise frequency from R, once each 18 months, to R24, at least once each 24 months.
TS 3/4.6.2, " Containment Spray System," TS 4.6.2.lc.1, regarding automatic valve actuation.
Revise frequency from once each 18 months to once each REFUELING INTERVAL.
TS 3/4.6.2, " Containment Spray System," TS 4.6.2.lc.2, regarding automatic spray pump actuation.
Revise frequency from once each 18 months to once each REFUELING INTERVAL.
3.2.2 Justification for the Chanae The containment spray (CS) system removes heat and fission products from the containment atmosphere and maintains the' containment sump pH within analysis limits following an accident.
The CS system consists of two redundant trains, each with a spray pump which takes its suction from the refueling water storage tank and spray additive tank. The pumps discharge to its spray header ring in containment.
In their submittal, the licensee stated that assurance of containment spray system operability is provided by many other surceillance tests and post maintenance tests during the operating cycle of the plant.
The automatic and manual actuations of the CS components are verified on an 18-month frequency. Manual actuation is verified during functional testing of the SI and Phase B actuation and reset switches. Automatic actuation is verified during slave relay testing.
The CS initiation is also tested during integrated system safeguards testing each refueling outage. The pump is tested quarterly in accordance with TS 4.0.5 as part of the, Inservice Testing Program.
The operating, surveillance and maintenance history of the containment spray system as well as review of industry experience support conclusion that the effect on safety of extending the surveillance interval is small and also indicates that there were no recurring surveillance / maintenance
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problems and no significant time related degradation mechanisms were found.
The staff reviewed the licensee's evaluation and finds it acceptable.
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3.3 Control' Room Ventilation System (CRVS) l 3.3.1 Pronosed TS chances 4
i TS 4.7.5.1 c.1 verifies that. the cleanup system satisfies the inplace penetration and bypass leakage testing acceptance criteria of less than 1 l
percent and uses the test procedure guidance in Regulatory Positions C.5.a.
C.5.c, and C.S.d of Regulatory Guide 1.52, " Design, Testing, and Maintenance l-Criteria for Postaccident Engineered-Safety-Feature Atmosphere Cleanup System Air Filtration and Adsorption Units of Light-Water-Cooled ' Nuclear Power i
4 Plants," Revision 2, March 1978, and the system flow rate is 2100 cfm i 10 perce,nt. The surveillance frequency would be extended to REFUELING INTERVAL.
I-TS 4.7.5.lc.2) regarding charcoal adsorber carbon testing on an 18 month i
frequency and under certain conditions, would be deleted. All control room ventilation system carbon tests would be combined into TS 4.7.5.1d.
TS 4.7.5.lc.3) verifies that the system flow rate is 2100 cfm 10 percent 3
during system operation when tested-in accordance with ANSI N510-1980.
The i
surveillance frequency would be extended to REFUELING INTERVAL.
TS 4.7.5.ld. regarding carbon sampling would be expanded to include the 4
18-month frequency and conditions currently associated with TS 4.7.5.lc.2),
j' above.
2 TS 4.7.5.le.1) verifies that the pressure drop across the combined high 4
efficiency particulate air (HEPA) filters and charcoal adsorber banks is less l
than 3.5 inches water gauge while operating the system at a flow rate of 2100 cfm 10 percent.
The surveillance frequency would be extended to REFUELING I
INTERVAL.
TS 4.7.5.1'e.2) verifies that on a Phase A isolation test signal, the system automatically switches into the p'ressurization mode of operation with approximately 27 percent (determined by damper position) of the flow through the HEPA filters and charcoal adsorber banks.
The surveillance freqaency j
would be extended to REFUELING INTERVAL.
i TS 4.7.5.le.3) verifies that the system maintains the control room at a positive pressure of greater than or equal to 1/8 inch water gauge relative to 2
i the'outside atmosphere during the pressurization mode of system operation.
The surveillance frequency would be extended to REFUELING INTERVAL.
-TS 4.7.5.1 e.4) verifies that the heaters dissipate 5 i 1 KW when tested in accordance with ANSI N510-1980.
The surveillance frequency would be extended j
to REFUELING INTERVAL.
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3.3.2 Justification for the Chanae Diablo Canyon Power Plant Units 1 and 2 share a common control room, but each maintains its own plant process computer room.
The units maintain separate control room ventilation and pressurization systems and plant process computer room air conditioning systems.
The CRVS for each unit has two separate trains consisting of a filter booster fan, a main supply fan, and 1 air cooling i
assembly.
In addition, each unit has one passive HEPA filter and charcoal adsorber assembly.
The control room pressurization system (CRPS) for each unit has two separate trains consisting of a pressurization fan and dampers.
The CRVS and CRPS are actuated to the accident alignment (pressurization mode) on either receipt of a containment Phase A isolation signal of high radiation detected at the CRVS inlet. The licensee requested administatrative changes to combine the various intervals and conditions when carbon testing is required into one surveillance requirement, TS 4.7.5.1d.
Since the licensee recently changed carbon testing methodologies they did not propose a
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surveillance extension.
The capacity and performance verification of CRVS/CRPS is performed using several tests on a 18-month frequency.
Automatic actuation of the pressurization mode is tested quarterly, and damper automatic alignment verification is performed each refueling. Automatic actuation is tested on.a refueling basis with the slave relay requirements of TS 4.3.2.
Operability of CRVS/CRPS is verified by other sorveillance requirements, such as acceptable control room temperature, and operation of all components is checked every 31 days.
The automatic damper actuation operability is verified by testing of the logic of the SSPS on a staggered monthly frequency.
The licensee stated that a review of the surveillance, maintenance and operating history indicated there are no time-dependent failures and problems and that the effect on safety of extending the surveillance interval is small.
The NRC staff finds the proposed changes acceptable.
3.4 Auxiliarv Guildino Safeauards Air Filtration System 3.4.1 Proposed TS chanaes 1
TS 4.7.6.1 b.1 verifies that the cleanup system satisfies the in-place penetration and bypass leakage testing acceptance criteria of less than 1 percent and uses the test procedure guidance in Regulatory Positions C.S.a, C.5.c, -and C.S.d of Regulatory Guide 1.52, Revision 2, March 1978, and the system flow rate is 73,500 cfm 10 percent.
The surveillance frequency would be extended to REFUELING INTERVAL.
TS 4.7.6.1 b.2, regarding charcoal adsorber carbon testing on an 18-month frequency and on certain conditions, would be deleted. All auxiliary building carbon tests would be combined into TS 4.7.6.1.c.
TS 4.7.6.lb.3 verifies that the system flow rate is 73,500 cfm 10 percent during system operation when tested in accordance with ANSI N510-1980.
The surveillance frequency would be extended to REFUELING INTERVAL.
TS 4.7.6.lc. regarding carbon sampling would be expanded to include the 18-month frequency and conditions currently associated with TS.4.7.6.1.b.2, above.
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TS 4.7.6.1d.) verifies'that the pressure drop across the combined high j
efficiency particulate air (HEPA) filters and charcoal adsorber banks is less i
than 3.7 inches water gauge while operating the system at a flow rate of 73,500 cfm 10 percent.
The surveillance frequency would be extended to i
REFUELING INTERVAL.
TS 4.7~6.1 d.2 verifies that flow is established through the HEPA filters and I
charcoal adsorber banks on a. safety injection (S1) test signal.- The 1
surveillance frequency would be extended to REFUELING INTERVAL.
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TS 4.7.6.1d.3) verifies that the heaters dissipate 5015 KW when tested in accordance with ANSI N510-1980.
The surveillance frequency would be extended to REFUELING INTERVAL.
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TS 4.7.6.1d.4) verifies that leakage through dampers M-2A and M-2B is less than or equal to 5 cfm when subjected to a constant pressure or pressure decay i
i leak rate test in accordance with ASME N510-1989.
The' surveillance frequency i
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'would be extended to REFUELING INTERVAL.
3.4.2 Justification for the Chanae s
The auxiliary building ventilation system (ABVS)- for each unit supplies i
filtered outside air to various locations in the auxiliary building. The system consists of two redundant sets of supply and exhaust fans, dampers and i
filter banks. An electric preheater,'and charcoal adsorber bank are also provided when safeguards filtration is required.
The ABVS provides ventilation and cooling to support safety-related equipment, and provides significant reductions in the amounts of airborne radioactive materials that could be released to the atmosphere after an accident.
The licensee requested administrative changes to combine the various intervals and conditions when carbon testing is required into one surveillance requirement, TS 4.7.6.lc.
Since the licensee.recently changed carbon testing methodologies they did not propose a surveillance extension. The capacity and performance verification
-of ABVS is performed using several tests on a 18-month frequency. Automatic actuation of the safeguards filtration mode is tested every refueling outage with slave relay testing requirements of TS 4.3.2.
Operability of ABVS is l
verified by other surveillance requirements such as and operation of components every 31 days.
The automatic damper actuation operability is verified by testing of the logic of the SSPS on a staggered monthly frequency.
-The licensee stated that a review of the surveillance, maintenance and operating history indicated there are no time-dependent failures and problems and that the effect on safety of extending the surveillance interval is small.
The NRC staff finds the proposed changes acceptable.
3.5 Fuel Handlina Buildina Ventilation $vstem 3.5.1 Proposed TS chanae TS 4.9.12b.1, verifies that with a system flow rate of 35,750 cfm 10 percent and exhausting through the HEPA fi.1ters and charcoal adsorbers, the damper M-29 is closed.
The surveillance frequency would be extended to REFUELING INTERVAL.
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TS 4.9.12b.2, verifies that the cleanup system satisfies the in-place penetration and bypass leakage testing acceptance criteria of less than 1 percent and uses the test procedure guidance in Regulatory Positions C.5.a, C.S.c, and C.5.d of Regulatory Guide 1.52, Revision 2, March 1978, and the system flow rate is 35,750 cfm 10 percent. The surveillance frequency would be extended to REFUELING INTERVAL.
l TS 4.9.12b.3, regarding charcoal adsorber carbon testing on an 18-month frequency and under certain conditions, would be deleted. All control room ventilation system carbon tests would be combined into TS 4.9.12c.
TS 4.9.12.b4, verifies that the system flow rate is 35,750 cfm 10 percent during system operation when tested in accordance with ANSI N510-1980. The surveillance frequency would be extended to REFUELING INTERVAL.
TS 4.9.12c. regarding carbon sampling would be expanded to include the 18-month frequency and conaitions currently associated with TS 4.9.12b.3),
above.
TS 4.9.12d.1, verifies that the pressure drop across the combined HEPA filters and charcoal adsorber banks is less than 4.1 inches water gauge while a
operating the system at a flow rate of 35,750 cfm fl0 percent.
The surveillance frequency would be extended to REFUELING INTERVAL.
TS 4.9.12d.2, verifies that on a high radiation test signal, the system automatically starts (unless already operating) and directs its exhaust flow through the HEPA filters and charcoal adsorber banks.
The surveillance frequency would be extended to REFUELING INTERVAL.
l TS 4.9.12d.3, verifies that the system maintains the spent fuel storage pool area at a negative pressure of greater than or equal to 1/8-inch water gauge relative to the outside atmosphere during system operation.
The surveillance frequency would be extended to REFUELING INTERVAL.
3.5.2 Justification for the Chanae The fuel handling building (FHB) ventilation system for each unit consists of two redundant sets of supply and exhaust fans with roughing and HEPA filters and charcoal adsorber banks. A third full capacity exhaust fan without a charcoal bank is provided for normal operation.
The system mitigates the consequences of a design basis fuel handling accident.
The system also supplies filtered outside air to the FHB to support personnel comfort and equipment cooling such as the auxiliary feedwater pumps.
The exhaust i
ventilation is drawn so as to sweep the surface of the spent fuel pool and is filtered and discharged via the plant vent. The exhaust fans are designed to have a larger capacity than the supply fans to create a negative pressure in the FHB to prevent the release of airborne iodine to the environment via unfiltered release paths during a postulated FHB accident.
The FHB ventilation system operates in either normal or iodine removal.
The difference is that in iodine mode the safety-related exhaust fan directs the air through charcoal adsorber banks, in addition to the roughing and HEPA filters. The licensee requested administrative changes to combine the various
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", i-intervals and conditions when carbon testing is required into one surveillance l
requirement, TS 4.9.12c.
Since the licensee recently changed carbon testing.
methodologies they did not propose a surveillance extension.
The capacity and.
performance verification of the FHB ventilation system is performed using several tests on a 18-month frequency. Automatic actuation of the safeguards filtration mode is tested quarterly to meet TS 4.3.3.1 radiation monitor j
channel functional testing requirements. This test also means that the startup of.one of-the safety-related exhaust fans with a safeguards filter train, automatic shutdown of the normal exhaust fan and closure of the associated inlet damper is tested quarterly. Operability of the FHB ventilation. system is verified by other surveillance requirements such as and operation of components every 31 days per TS 4.9.12a. The licensee stated that a review of the surveillance, maintenance and operating history indicated there are no recurring failures and problems and that the effect on safety of extending the surveillance interval is small. The NRC staff finds the proposed changes acceptable.
4.0 STATE CONSULTATION
In accordance ~with the Commission's regulations, the California State official was notified of the proposed issuance of the amendments. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
T'ese amendments change surveillance requirements. The NRC staff has h
determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite,.and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a i
proposed finding that the amendments involve no signif.icant hazards l
consideration, and there~has been no public comment on such finding (61 FR 52966). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issu'ance of the amendments.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors: S.V. Athavale S. Bloom T. Dunning Date:
April 14,1997