ML20209F916
| ML20209F916 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 09/05/1986 |
| From: | Whittier G Maine Yankee |
| To: | Thadani A Office of Nuclear Reactor Regulation |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 GDW-86-203, MN-86-111, NUDOCS 8609120306 | |
| Download: ML20209F916 (5) | |
Text
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MAME HARHEE AIGMICPOWERCOMPARUe
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(207) 623-3521 O
September 5, 1986 MN-85-111 GDH-86-203 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C.
20555 Attention:
Mr. Ashok C. Thadani, Director PWR Project Directcrate #.8 Division of Licensing
References:
(a) License No. DPR-35 (Docket No. 50-309)
(b) USNRC Letter to HYAPCo dated March 13, 1986 - Technical Evaluation Report of Maine Yankee Conformance to Regulatory Guide 1.97, Rev. 3 (c) MYAPCo Letter to USNRC dated June 17, 1986 9MN-86-81) -
Additional Information on Exceptions to Regulatory Guide 1.97
Subject:
Additional Information on Exceptions to Regulatory Guide 1.97 Gentlemen:
In Reference (c), Maine Yankee provided a partial response to your request for additional information on Regulatory Guide 1.97 exceptions, Reference (b),
and committed to providing the remaining information by August 30, 1986.
Attachment A contains the remaining additional information per your request.
Please contact us if you have any questions.
Very truly yours, MAINE YANKEE ATOMIC POWER COMPANY N h NVh G. D. Whittier, Manager Nuclear Engineering and Licensing GDH/bjp Attachment cc: Dr. Thomas E. Murley Mr. Pat Sears dg Mr. Cornelius F. Holden i
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MAINE YANKEE ATOMIC POWER COMPANY ATTACHMENT A 2.
NRC Reauest Radiation Exposure Rate Monitors - The Licensee should show that the instrument range is greater than the expected radiation levels at their locations.
2.
Maine Yankee Response It is Maine Yankee's philosophy that portable instrumentation used for post-accident surveys determines whether or not the areas being surveyed are available for access during post-accident conditions. Access to areas with radiation levels above the range of the available instrumentation would have the same or more severe restrictions on access as those areas with levels at the top range of the survey instruments.
- 12. NRC Reauest Steam Generator Pressure - The licensee should provide the recommended overrange capabilities.
- 12. Maine Yankee Response A modification is planned to upgrade the steam generator pressure channels to provide the overrange capability to 1200 psig.
The modification is scheduled for Maine Yankee's 1988 refueling.
- 14. MBC Reauest Containment Spray Flow - The licensee should show that the spray valve position indication is Category 2 and addresses flow blockage and pipe rupture.
- 14. Maine Yankee Response Based on a reassessment of our original response regarding containment spray system flow, Maine Yankee will install flow instrumentation which will be used to measure spray flow.
This additional instrumentation will be Category 2 as per Regulatory Guide 1.97.
The installation will take place during Maine Yankee's 1988 refueling.
The instruments noted in our original submittal will then be dropped as being Regulatory Guide 1.97 instruments.
- 18. NRC Reauest Letdown Flow-out - Environmental qualification should be addressed in accordance with 10 CFR 50.49.
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MolNE YONKEE ATOMIC POWER COMPANY 18. Maine Yankee Resoonse Letdown Flow-out was addressed in accordance with 10 CFR 50.49, in that, it was determined that this instrument was not required to function for any accidents which are analyzed in the Maine Yankee FSAR.
If there is a harsh environment outside containment in the area of the Letdown Flow transmitter, then the operators would utilize the alternate letdown system (High Pressure Drain System) to perform the same function.
The flow indication (FT-217) would, in this case, need not be qualified because the accident is outside the containment.
If the accident is inside j
containment, then the alternate letdown system would not be needed because normal letdown would be available, with its normal indication.
- 19. NRC Reauest Component Cooling Hater Flow to Engineered Safety Features System Components - The licensee should provide the recommended instrumentation or identify alternate instrumentation that provides the same information and satisfies the regulatory guide.
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- 19. Maine Yankee Response Flow instrumentation, for primary component cooling and for secondary l
component cooling, will be installed to measure flow through the systems.
The channels will be installed to meet Category 2 criteria.
The installation will take place during Maine Yankee's 1988 refueling.
- 20. NRC Reauest Radioactive Gas Holdup Drum Pressure - The licensee should either submit i
additional justification for local readout only, or provide the recommended instrumentation.
- 20. Maine Yankee Responie A review of the plant layout has been performed to show that the local readout is accessible for post accident use.
Based on this review, no further modifications are planned.
- 21. NRC Reauest Containment or Purge Effluent - The licensee should submit additional information and justification concerning the instrumentation for this variable or provide the recommended instrumentation.
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M AINE YANKEE ATOMIC POWER COMPANY,
- 21. Maine Yankee Response Regulatory Guide 1.97, Rev. 3 states that containment or purge effluent monitoring instrumentation is "not needed if effluent discharges through common plant vent." Maine Yankee's FSAR in Section 5.1.3.4 (Containment Ventilation - System Operation) states (page 5-58):
"The exhaust ventilation purge for FN-48 is operated to draw air from the 1
area inside the crane wall and discharge it through the primary vent
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stack."
The same FSAR section on page 5-59 states:
i "The ventilation and purge fan is operated to direct containment exhaust air through the containment purge and ventilation filter located in its own enclosure adjacent to the primary auxiliary ~ building prior to discharge through the primary vent stack."
Based on the above, no modifications are planned.
- 22. NRC Reauest Vent from Steam Generator Safety Relief Valves - The licensee should submit additional information and justification concerning the instrumentation for this variable or provide the recommended instrumentation.
- 22. Maine Yankee Resoonse The Maine Yankee steam generator safety valves are sixteen inch spring i
operated safety valves located in each main steam line between the steam generator and the non-return valve.
Each steam line is equipped with six safety valves set to open at successively higher steam pressures between 985 psig and 1035 psig. Nominal system pressure at full power is 835 psig.
The steam generator safety valves are not opened during normal plant operation. During off-normal situations, such as a loss of turbine load or an inadvertant excess flow check valve closure which cause a high steam generator pressure, the safety valves open to prevent over pressurizing the steam generators or the main steam line.
The safety valves relieve to the atmosphere.
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-sa MAINF YANXCE ATOWC POWin CCMPANY 4
In the event that a steam generator safety valve is lifted, the noise caused by. relieving steam in excess of 985 psig to the atmosphere can be heard in many areas inside the plant, such as the maintenance office, the HP checkpoint, the locker rooms, and the cafeteria. Outside the plant the noise can be heard anywhere around the plant as well as on Westport Island about a mile from the plant. Additionally, the steam can be seen being relieved between the containment building and the turbiae building from three of the continuously manned security guard t0wers around the plant.
In the past, when Maine Yankee has lifted a safety valve, the noise has been reported to the control room by the security guards as well as by residents adjacent to the plant.
1.
Procedures will be established to require the guard tower security guard to notify the control room of a lifted safety valve.
Maine Yankee has not experienced a stuck open steam generator safety valvo in nearly fourteen years of plant operation.
Six valves are functionally tested each refueling interval to demonstrate proper function and to verify valve setpoints. All valves are functionally tested over a three cycle interval. Notwithstanding, in the unlikely event that a steam generator safety valve were to stick open, the plant operators would react to the resulting plant cooldown regardless of their knowledge of the cause. Maine Yankee's recently adopted Hestinghouse based emergency operating procedures would require the event to be treated similar to a steam line break where the initiating symptoms are any steam generator depressurizing or pressure decreasing in an uncontrolled manner. Other symptoms could include steam generator low level where the affected steam generator was not isolated or a steam flow / feed flow mismatch associated with a faulted steam generator. The emergency procedure requires isolation of the faulted steam generator by securing feed to and steam from the faulted steam generator.
For the forgoing reasons, Maine Yankee does believe backfitting the steam generator safety valves with position indication is neither necessary nor warranted. He do not believe a stuck open safety valve is likely, however, if it were to happen, it would not go unnoticed nor would it cause a significant safety concern.
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