ML20133M658
| ML20133M658 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 10/22/1985 |
| From: | Papanic G YANKEE ATOMIC ELECTRIC CO. |
| To: | Zwolinski J Office of Nuclear Reactor Regulation |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097, TASK-03-06, TASK-3-6, TASK-RR FYR-85-113, NUDOCS 8510280175 | |
| Download: ML20133M658 (6) | |
Text
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q YANKEE ATOMIC ELECTRIC COMPANY Tc'epho"c (6 ") *' -oo TWX 710-380 7619 i.,.
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1671 Worcester Road, Framingham, Massachusetts 01701 2C21
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FYR 85-113
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t October 22, 1985 United States Nuclear Regulatory Commission Washington, DC 20555 Attention:
Mr. John A. Zwolinski, Chief Operating Reactors Branch No. 5 Division of Licensing
References:
(a) License No. DPR-3 (Docket No. 50-29)
(b) YAEC Letter to USNRC, dated August 30, 1983 (FYR 83-81)
(c) YAEC Letter to USNRC, dated January 19, 1984 (FYR 84-08)
(d) YAEC Letter to USNRC, dated July 16, 1984 (FYR 84-77)
(e) USNRC Letter to YAEC, dated August 6, 1985 (NYR 85-134)
Subject:
Response to Open Items - Regulatory Culde 1.97
Dear Sir:
Attached are the responses to the open items in Section 4 of your Interim Evaluation Report forwarded by Reference (e).
We hope that this information is satisfactory and request that you contact us with any questions on this information.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY a
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C. Papan c, Jr.
Senior Project Engineer Licensing GP/mec gj0280175851022 ADOCK 05000029 F
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ATTACHMENT Page 1 of 5
- Response to Section 4, Conclusions of EG&G Idaho, Inc., Report "Conformance to Regulatory Guide 1.97," dated February, 1985.
Section 4 Item 1 Environmental qualification of the instrumentation listed in Appendix A should be addressed in accordance with 10CFR50.49.
Yankee Responce As discussed in Section 3.3.1 of the EG&G report, the guidance of Regulatory Guide (RG) 1.97 has been superseded by 10CFR50.49. The Yankee Environmental Qualification Program contains all of the equipment identified by Yankee required to meet the requirements of 10CFR50.49 which does include applicable Regulatory Guide 1.97 required components. As per Reference (d), once the Regulatory Guide 1.97 review is completed and all items resolved, the equipment qualification program will be revised as necessary to incorporate any additional Regulatory Guide 1.97 items.
Section 4 Item 2 The instrumentation listed in Appendix B should be seismically qualified in compliance with the regulatory guide.
Yankee Response During the Systematic Evaluation Program (SEP), the seismic design criteria was established for Yankee with staff concurrence. As part of the seismic upgrade of the plant, Yankee committed to install the Hot Shutdown System, since renamed the Safe Shutdown System (SSS). This system will have the following seismically qualified instrumentation:
Pressurizer level Pressurizer pressure Core exit thermocouples (2)
Cold leg temperature (one per loop)
Steam generator level (one per loop)
Steam generator pressure (one per loop)
This is the only instrumentation identified to require seismic qualification at Yankee per the Integrated Plant Safety Assessment (NUREG-0825, IPSAR l
Section 4.11, Topic III-6, Seismic Design Considerations).
Section 4 Item 3 i
Neutron Flux - The licensee should provide redundant power sources.
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Yankee Response l
l Ten nuclear instrumentation (NI) channels are powered from Vital Bus 1, one refueling source range channel is powered from Transformer A, off Emergency MCC-1, and another normally will be available for use from the Safe Shutdown
ATTACHMENT Page 2 of 5 System. The range of the refueling source range channels is 1 to 100,000 counts per second, which is the same as the source range channels powered from Vital Bus 1.
Loss of Vital Bus 1 power to the NI cabinets results in de-energizing Relays SR1 and SR2 which cause the scram breaker (BK1 and BK2) tripping coils to be energized from Battery Bus 2, scramming the reactor. The scram can be veritied by rod position indication which is powered from Distribution Cabinet A fed from Emergency MCC-1.
The design is such with the loss of Vital Bus 1 power to the NI channels, the reactor will trip thus accomplishing their protection function.
Since the Category 1 function will have been accomplished, there is no need for the verification components to be better than Category 3.
Section 4 Item 4 Containment isolation valve position - The licensee should provide redundant Class 1E power sources for this instrumentation.
A. Class IE power source is supplied for each single autotatic containment isolation valve, and redundant power supplies are only applicable if there are redundant automatic isolation valves.
Yankee Response A single automatic containment isolation valve is provided in each line not normally isolated. The containment isolation provisions at Yankee were reviewed and accepted by the staff in the SEP (NUREG-0825, Section 4.22, f
Topic VI-4, Containment Isolation System). As stated in Section 3.3.7 of the EG&G report, redundant indications per valve is not intended by the regulatory guide.
Section 4 Item 5 Flow in Low Pressure Injection (LPI) System - The licensee should provide the recommended instrumentation.
Yankee Response In Section 3.3.11 of the EG&G report, the statement is made that the LPI System has a long-term recirculation function and, therefore, LPI flow indication is required. This is not the case at Yankee.
Initially af ter the initiation of safety injection for a large break accident, the Low Pressure Safety Injection (LPSI) pumps and the High Pressure Safety Injection (HPSI) pumps take a suction from the safety injection tank and discharge through separate headers into the Main Coolant System (MCS). The LPSI and HPSI headers discharge into each of four main coolant loops. The LPSI and HPSI connections to each loop are joined together and connect to the loop through one common pipe connection. This common section of pipe has a flow meter that indicates total flow to each loop, both LPSI and HPSI flow.
Therefore during the injection phase, LPSI flow can be determined by comparing HPSI header flow to the drop in safety injection tank level or by comparing HPSI header flow to the individual loop flows.
ATTACHMENT Page 3 of 5 When safety injection tank level drops to a predetermined level, the injection phase is terminated and long-term recirculation begun. The suction of all pumps is realigned to the containment sump, the safety injection tank is isolated, and the LPSI header is isolated.
In this alignment, the LPSI pumps take a suction frem the containment sump and discharge to the suction of the HPSI pumps. The HPSI pumps then discharge through the 1 PSI header to all four main coolant loops. Therefore, during the long-term recirculation mode, all safety injection flow is through the HPSI header and is indicated on its flow meter. During recirculation, the LPSI header is isolated and provides no safety injection flow.
Section 4 Item 6 Pressurizer heater status - The licensee should provide Category 2 current instrumentation for this variable.
Yankee Response In Section 3.3.13 of the EG&G report, the following two reasons are given for requiring pressurizer heater current:
1.
To prevent overloading of a diesel generator.
2.
For Technical Specification required surveillance.
To prevent overloading of a diesel generator, indication is provided of generator volts, amps and kilowatts in the Main Control Room. Therefore, before energizing pressurizer heaters or any other loads on the diesel generator, the operator can determine the capacity available on the diesel generator. Also, if a load causes an overload condition, the operator can determine this immediately and shed loads to correct the condition.
Present Yankee Technical Specifications do not require measuring heater current. If this was required, pressurizer heater current can be easily determined using the kilowatt-hour meter and bus voltage.
This would be acceptable for a surveillance requirement.
Section 4 Item 7 Auxiliary or emergency feedwater flow - The licensee should provide justification for the deviation or change the range to comply with the recommended range.
Yankee Response The design flow for the Emergency Feedwater System is 80 gpm.
Therefore, the instrument range of 0 to 150 gpm provides the required coverage.
Section 4. Item 8 Containment atmosphere temperature - The licensee should provide the recommended range; environmental qualification should be addressed in accordance with 10CFR50.49.
ATTACRMENT Page 4 of 5 Yankee Response Containment atmosphere temperature is a type D variable.
Regulatory Guide 1.97 defines a Type D variable as one "that provides information to indicate the operation of individual safety systems and other systems important to safety. These variables are to help the operator make appropriate decisions in using the individual systems important to safety in mitigating the consequences of an accident."
In most modern plant designs, containment atmosphere temperature is lowered and maintained by operation of a Containment Spray System.
In this case, proper operation of the Containment Spray System is verified by monitoring containment atmosphere temperature. The Yankee plant does not have a Containment Spray System. Heat is dissipated by the metal skin of the containment.
In fact, all decay heat from the reactor is dissipated by this passive method for the design basis accident. The water in the containment sump is cooled by heat loss through the containment metal skin.
The Safety Injection System takes this water from the containment sump and returns it directly to the reactor without going through any forced cooling heat exchanger. Therefore, the operator monitors the operation of the containment safety function through core temperature indication and containment pressure.
If core temperature is stable or dropping and containment pressure is dropping, the containment is performing its safety function.
If core temperature is increasing, the only recourse the operator has is to inecease safety injection flow to the reactor.
Indication of containment atmosphere temperature is not useful to the operator. The operator has no way to change it, and the indication that the operator must monitor and control is core temperature. The operator can affect this only by adjusting safety injection flow.
The containment atmosphere temperature provided is for monitoring containment temperature during normal operation. This indication is used to monitor normal operation of the Containment Ventilation, Heating and Cooling Systems.
These temperature indications da not provide an accident monitoring function for Yankee's passive type of Containment Cooling System.
Section 4 Item 9 Containment sump water temperature - The licensee should provide the recommended instrumentation.
Yankee Response In Section 3.3.17 of the EG&G report, it states that containment sump water temperature affects the operation of the emergency core cooling pumps in the recirculation mode. Yankee concurs that sump water temperature has an effect on pump Net Positive Suction Head (NPSH). When recirculation operation was analyzed at Yankee, it was assumed that the sump water was at saturation conditions. Containment pressures were then determined that would provide adequate NPSH for pump operations in this condition. The containment pressures for various pump operation were then conservatively set.
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ATTACHMENT Page 5 of 5 The emergency procedure for loss-of-coolant accidents uses containment pressure indication as the guide to the operators for safety injection pump operation. When recirculation operation begins, the number of pumps allowed to run is based on containment pressure. As discussed above, the values of containment pressure have been conservatively chosen to take into account sump water temperature. Therefore, the function of the containment sump water temperature indication has been provided by containment pressure indication.
Section 4 Item 10 Radioactive gas holdup tank pressure - The licensee should either show that the range is adequate or comply with the upper limit of range recommended.
Yankee Response The waste gas surge drum has a design pressure of 100 pulg. The pressure instrument for this tank has a range of 0 to 100 psig. This instrument is acceptable for the following reasons:
1.
In the 25-year operating history of this plant, the tank pressure has not been above approximately 50 psig.
2.
The tank is protected by a spring-loaded safety valve set to relieve at 100 psig. This insures that the tank will not exceed the indicated range.
3.
The waste gas compressors are only capable of developing a discharge pressure of 84 psig.
4.
Accident analysis assuming the release of the contents of the entire Waste Gas System resulted in an off-site dose well below the allowed values in 10CFR100.
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