ML19350B712
| ML19350B712 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 03/19/1981 |
| From: | Heider L YANKEE ATOMIC ELECTRIC CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| FYR-81-43, NUDOCS 8103230469 | |
| Download: ML19350B712 (11) | |
Text
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o YANKEE A10MIC ELECTRIC COMPANY h
1671 Worcester Road, Framingham, Massachusetts 01701 Ya{uxes rra 81-43 March 19, 1981 d
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4 United States Nuclear Regulatory Commission g
3 Washington, D. C.
20555 Attention:
Mr. Harold R. Denton, Director b
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Office of Nuclear Reactor Regulation m
References:
(a) License No. DPR-3 (Docket No. 50-29)
(b) USNRC Letter dated November 24, 1980,
Subject:
Revised Section 10CFR50.48 and New Appendix R to 10CFR50.
Subject:
Compliance with Appendix R to 10CFR50
Dear Sir:
Yankee Atomic Electric Company has reviewed the extensive criteria contained in the revised Section 50.48 and the new Appendix R to 10CFR50, d'aling with fire protection. The following information is submitted in accordance with the schedule promulgated in Section 50.48(c)(1) through (5).
Section IIIG, Fire Protection of Safe Shutdown Capability Yankee Atomic Electric Company has complied with this section by way of the development of an alternative shutdown capability. The description of this alternative shutdown capability is attached as Attachment A.
Section IIIJ, Emergency Lighting Yankee Atomic Electric Company has investigated the existing Emergency Lighting, and finds that it currently complies with the requirements in Section IIIJ of Appendix R.
Section IIIO, Oil Collection System for Reactor Coolant Pumps Yankee Rowe uses canned rotor reactor coolant pumps, which do not require oil lubrication. Therefore, this section does not apply to Yankee Rowe.
Section IIIH, Fire Brigade Yankee Rowe has removed the responsibility of fire brigade leader from the Shift Supervisor. He is now neither leader nor member of the fire brigade. The Shift Technical Advisor has assumed the responsibility of Shift Fire Brigade Leader. This previously open item is now in compliance with Appendix R and is considered closed.
'8103230 %f P
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March 19, 1981 U.S. Nuclear Regulatory Commission Page 2 Mr. Harold R. Denton Schedule We expect that the modifications required by Section III.G of Appendix R
( Alternative Shutdown Capability) will be installed during the 1982 refueling However, we wish to point out that this schedule, as imposed by is dependent on a timely review by your staff.
outage.
10CFR50.48, paragraph (c)(4),
If NRC approval is delayed beyond the next six (6) months, we expect that procurement and delivery of equipment necessary for the modifications will This would jeopardize system installation during the 1982 refueling outage. re presently scheduled for early 1984.
Furthermore, we wish to point out that the integrated assessment that culminates the Systematic Evaluation Program for Yankee Rowe is now scheduled The results of that assessment could potentially have a for early 1982.
significant impact on the installation of the the alternative shutdownWe have cons capability required by Appendix R. decisions on significant modifications to th integra'ed assessment-is complete thus enabling optimization of pla modifications.
identify' the difficulty.
We trust that the above information is sufficient for your review.
However, if you have any questions or desire additional information, please contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY cM#' L L. H. Heider Vice President Attachment
e s
ATTACHMENT A Alternative Safe Shutdown Capability Required by Appendix R of 10CFR50 DISCUSSION:
-The Alternative Safety Shutdown System (ASSS) for Yankee Rowe employs existing plant systems located outside of the Fire Zone using new instrumentation, control and power supplies where required. The system is conservatively designed for the hypothetical loss, due to a fire, of all equipment in the Turbine Building, Control room and Switchgear room combined with a loss of all offsite ac power.
The ASSS is further designed such that all required power supplies, cabling and instrumentation are independent of the Turbine Building, Switchgear Room, Control Room, and any other important areas such as Manhole #3 and any single run in the Primary Auxiliary Building (PAB).
The ASSS is designed in accordance with the requirements of Appendix R to 10CFR50 as further clarified in the NRC Generic Letter 81-12, dated February 20, 1981.
FUNCTIONAL DESCRIPTION The Alternative Safe Shutdown System function is to assure that the plant can be brought to and kept in a safe cold shutdown condition for as long as necessary in the event of a hypothetical fire in the turbine building. To accomplish this objective, a core heat removal path must be established. A schematic of the systems required is shown on Figure 1.
The ASSS is designed to. remove. heat from the core via the steam generators using one train of the low.and high pressure safety injection system (LPSI and HPSI). A single train of the LPSI and HPSI pumps powered by the emergency diesels will be lined up to feed the ' steam generators through an existing blowdown line connection. The initial source of cooling water is the Safety Injection Tank. -The steam produced is routed to the secondary vent stack via the secondary safety and steam dump valves.
In order to control primary system pressure and volume during the cooldown period, pressurizer heaters and charging pumps will be used. The plant could either be held in a hot shutdown condition for an extended period or cooldown could commence by controlling the steaming rate and the feed rate from the LPSI 'and HPSI train. Cooldown'to approximately 3300F would be accomplished in this configuration. At that point, shutdown cooling and component cooling water pumps with their respective system heat exchanger will be used to reach cold shutdown within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Power for these pumps would be provided by the emergency diesels. The final heat sink for the component cooling system will be either the fire system, fire truck or other portable pump system.
To assure that electr.;al circuits not required for' Safe Shutdown do not compromise the Safe Shutdown function, all AC and DC circuits in the fire area will be disconnected prior to evacuation of the control and switchgear room.
All requ' red power will be provided by the emergency power supplies on site.
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SYSTEM DESCRIPTION Feedwater An Alternate Emergency Feedwater System will be used which is ind ? pendent of both Normal Emergency Feedwater Systems. The system draws feedwater from the Safety Injection Tank utilizing the #3 Low Pressura Safety Injection Pump and the #3 High Pressure Safety Injection Pump which are powered by the #3 Emergency Diesel Generator.
The flos is directed from the discharge header to a cross tie with the Steam Generator Plowdown System and then to the feedwater ring of each of the four steam generators. All manual valving is located in either the Safety Injection Building or the Primary Auxiliary Building. The Safety Injection Tank has a minimum of 117,000 gallons available for feeding, with make-up on a temporary connection basis from the Primary Water Storage Tanks with a combined minimum storage of 85,000 gallons.
In addition, water from Sherman Pond can be utilized if supplies of on-site water are depleted over a long period of time.
The alternate feed path, as can be seen on Figure 2 is routed via the upper pipe chase and is completely independent of the main feedwater flowpath outside the containment. The normal emccgency feedwater flowpath is via the main feed lines. The steam is vented to the secondary vent stack via piping for the safety valves and steam dump valves located outside the Fire Area.
Main steam line isolation is assured by the Non Return Valves (NRV) located just downstream of the Safety Valves and Atmospheric Dump Valves. The NRV's are located outside the Fire Area.
Charging and Bleed System A charging pump and associated motor operated valves will be powered by the #3 Diesel Generator and will be available to makeup to the primary system for shrinkage on cooldown.
The charging system will also be capable of directing the spray into-the pressurizer steam space to cool the pressurizer and reduce primary pressure during cooldown or to borate the primary system for cold shutdown.
Bleed control will be available via a motor. operated vari-orifice located inside containment and operated from the ASSS console. This will provide letdown in the event of a primary system swell should one occur.
Pressurizer Heaters One group of pressurizer heaters will be powered by #3 Diesel Generator and will be available to maintain primary pressure. One group of heaters is capable of maintaining a hot standby condition.
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Shutdown Cooling A shutdown cooling pump and a component cooling pump with their respective system heat exchangers will be utilized to reach cold shutdown within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as required.
Power for the pumps and necessary motor operated valves will be supplied by #3 Diesel Generator.
Power for the component cooling pump will be supplied by the #2 Diesel Generator utilizing temporary connections.
The final heat sink for the component cooling system will use either the fire system if it is available or a fire truck or other portable pump in the event that the onsite fire pumps are unavailable.
Supporting Equipment Additional supporting equipment such as communications, lighting and tempotary fuel lines to refill the diesels day tanks will be provided to support the hot shutdown and cooldown.
In s t rumenta tion All the necessary process monitoring instrumentation for safe shutdown and cooldown will be provided at the ASSS or readily accessible locations as necessary. New instrumentation channels will be installed for the ASSS console -or signals will be transferred from the Control Room via transfer switches which are located outside the Fire Area.
In some cases local instrumentation within the PAB or safety injection building already exists.
No instrumentation cables will pass through the Fire Area. A li ting of the requ'is.d instrumentation is detailed in Table 1.
Electrical Pawer Supplies DC and AC alectrical power supplies are provided by the #3 Station Battery and-the #3 Diese1' Generator, both located in the Safety Injection Building. The
- 3 Battery is used to start #3 Diesel Generator. This battery also powers a new inverter which provides power to a new. vital instrumentation bus.
Battery Charger #3 is powered from the #3 Diesel Generator.
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A one line diagram showing the existing electrical equipment, the new ASSS, motor control center and the new loads is shown on Figure 3.
It should be noted that although only one diesel generator is required to carry the loads, temporary connections and necessary instrumentation have been supplied to enable utilization of the #2 Diesel Generator for shutdown cooling.
All electrical equipment shown on Figure 3 is isolated from the Fire Area via the transfer switches. A typical circuit diagram for one of the loads normally supplied from the switchgear room and alternately supplied from the ASSS is shown in Figure 4.
Electrical Design Criteria All new electrical components that interface existing Safety Class components will be designed and specified to the same criteria as the existing components.
Those circuits which are not required for safe shutdown but could prevent safe shutdown are prevented from doing so by disconnecting the power from all of those circuits.
This can be done readily by disconnecting power from each of the normal station buses prior to forced evacuation of the switchgear room and control room. DC supplies can be disconnected from the switchgear room or the Safety Injection Building. The six normal station service breakers can be opened from either the switchgear room or the control room. A fire barrier exists.between these two rooms such that simultaneous forced evacuation is considered an incredible event.
By opening the normal station service breakers a loss of ac results for all circuits within the Fire Area which ccald prevent safe' shutdown due to spurious operation of the circuits. The same actions for the DC supplies would be taken.
Isolation of the power supplies and controls to the circuits would follow the starting of 43 Diesel and the transfer of the safe shutdown circuits to the new ASSS motor control center.
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Table 1 Instrumentation For Safe Shutdown
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Instrument Number of Ins t rumen t Location Channels Pressurizer Wide Range Level Containment 1
Pressurizer Pressure Containment 1
Steam Generator Wide Range Levels Containment 4(one per loop)
Incore Thermocouples or Loop TH's Containment 2
Neutron Detector Containment 1
Steam Generator Pressure Non Return Valve 4(one per loop)
Platform Shutdown Cooling Inlet Temperature PAB 1
Shutdown Cooling Outlet Temperature PAB 1
Component Cooling Inlet Temperature PAB 1
Component Cooling Outlet Temperature PAB 1
Diesel Generator (D.C.):
Water Temperature D.C. Cubicle 1 per D.G.
5 Oil Pressure D.G. Cubicle 1 per D.G.
Frequency ASSS Console 1 per D.G.
Voltage-ASSS Console 1 per D.G.
Amperage:
.ASSS Console-1 per D.G.
' KW ASSS Console 1 per D.G.
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