ML19345E141
| ML19345E141 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 12/12/1980 |
| From: | Withers B PORTLAND GENERAL ELECTRIC CO. |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8012230313 | |
| Download: ML19345E141 (6) | |
Text
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Trojan Nuclear Plant Docket 50-344 License NPF-1 1
Director of Nuclear Reactor Regulation ATTN:
Mr. Robert A. Clark, Chief Operating Reactors Branch No. 3 Division of Licensing U. S. Nuclear Regulatory Commission Washington, DC 20555
Dear Sir:
Attached please find a copy of the supplemental information regarding the-Trojan Nuclear Plant Auxiliary Feedwater System which responds to Items GS-5 and Additional Long-Term Recommendation 5 in the enclosure to your letter dated October 23, 1980. An update of the progress made in this area has also been included. This submittal completes the scope of PGE's response to the aforementioned NRC letter.
Sincerely, a
Bart D. Withers Vice President Nuclear Attachment c:
Mr. Lynn Frank, Director j
State of Oregon 00i Department of Energy
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k ATTACHMENT Trojan Nuclear Plant PGE Supplemental Response to the October 23, 1980 NRC Request on the Auxiliary Feedwater System I
A.
Short-Term Recommendations
" Recommendation GS-5
'The as-built plant should be capable of providing the required AFW flow for at least two hours from one AFW pump. train, independent of any alternating current power source. If manual AFW system initiation or flow control is required following a-
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complete loss of alternating current power, emergency procedures should be established for manually initiating and controlling the system under these conditions. Since the water for cooling of the lube oil for the turbine-driven pump bearings may be dependent on alternating current power, design or procedural changes shall be made to eliminate this dependency as soon as practicable. Until this is done, the emergency procedures should provide for an individual to be stationed at the turbine-driven pump in the event of the loss of all alternating current power to monitor pump bearing and/or lube oil temperatures.
If necessary, this operator would operate the turbine-driven pump in a manual on-off mode until alternating current power is restored. Adequate lighting powered by direct current power sources and communications at local stations should also be provided if manual initiation and control of the AFW system is needed. (See Recommendation GL-3 for the longer-term resolution of this concern.)'
"In response to this recommendation, the licensee indicated in a letter dated December 31, 1979 that the turbine-driven AFW pump vould be utilized to provide decay. heat removal in the event of a loss of all AC power. However, this pump currently relies on an AC power dependent water source for bearing and jacket cooling. The licensee is implementing emergency procedures to provide the following:
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a) Make every effort to restore AC power within 20 minutes.
b) Provide a material " kit" for use by the operators which provides the necessary hardware to hook up temporary cooling water to the turbine-driven AFW pump bearing l
lube oil cooler.
c) Provide a procedure that instructs the operator to hook up the temporary cooling system if AC power is not restored within 20 minutes, manually valve in the steam supply to the AFW pump turbine and align the condensate storage tank and AFW pump to feed the steam generators.
The procedure will include a statement directing the operator to take portable lighting and portable communi-cation devices with him to the 'ARJ pump operation station.
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"If the above measures are required, an individual will be stationed i
at the turbine-driven pump to monitor pump.-bearing and/or lube oil temperatures.
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O Attachment Page two
" Based on our review, we conclude that the licensee's response is not acceptable. We require the following additional information from the licensee:
a) What is the basis for taking no action for the first 20 minutes following station blackout? Indicate the time required for installing the temporary " kit" and establishing AFW flow.
b) Provide a diagram of the temporary cooling system.
c) Where is the temporary cooling " kit" to be located and 1
what administrative controls will be included to assure its availability?
d) Verify that all necessary personnel have been trained in the procedure for installing the temporary cooling system.
"We will report resolution of this item in a supplement to this SER."
PGE Response The steam-driven auxiliary feedwater pump is now capable of providing the required AFW flow for at least 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> independent of any AC power-dependent water source. The modification described in the response to Long-Term Recommendation GL-3 in the PGE letter dated
' July 1, 1980 has been completed. Therefore, the NRC questions based on the short-term solution are no longer applicable.
C.
Long-Term Recommendations Additional Recommendation 5
" Recommendation
'A motor-driven pump is currently being installed or i
is planned to be installed by the licensee. Present plans are for a non-safety grade motor-driven pump system.. Based on past experience l
of the problems associated with the speed control-(overspeed trips) of both the diesel and turbine-driven pumps and other Licensee Event Reports on the Trojan AFW system, the licensee should further review the proposed installation to determine if the motor-driven pump should be safety grade and automatically actuated by the _ AFW automatic start logic.'
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"In response to this recommendation, the licensee stated in a letter dated December 31, 1979 that it is felt that upgrading.the new
, motor-driven AFW. pump to safety grade or automatic start is not justified. In lieu, the licensee proposes to develop a procedure-which will provide for manually switching the motor-driven pump to an emergency AC bus and manually starting this pump in the event normal
Attachment Page three suction supply from the condensate storage tank to the safety grade AFW pumps is unavailable or both safety grade AFW pumps fail to operate. These actions can be accomplished from the control room, and closely parallel the operator actions that would be necessary to verify that the motor-driven pump had auto started. The licensee concludes that the design for the motor-driven pump as presented including the above procedure will substantially enhance AFW system reliability for the case of loss of main feedwater and loss of of fsite power.
"We have reviewed the licensee's response and conclude that it is incomp.ete. Licensee's final conclusions as to the feasibility of supplying emergency power to the new motor-driven pump should be provided, together with details as to how this would be done, in order that we may assess the complexity of the evolution and the aawunt of time it would take for the necessary manual operations to be performed. The capability of a diesel generator to start the motor-driven pump should be discussed.
" Reliability studies for other AFW systems employing a manually started pump suggest that a significant improvement in reliability is achieved by automatic starting. Licensee should present additional justification for manual (emergency power) alignment and for manual starting from a reliability standpoint, including a discussion of gains in reliability that could result by providing emergency power from one or both diesel generators.
"We will report our resolution of this matter in a supplement to this SER."
PGE Response The above requests for information have -been itemized and answered as follows:
1.
What is the licensee's final conclusion as to the feasibility of supplying emergency power to the new motor-driven pump?
Re sponse:
It is concluded that powering the motor-driven auxiliary feedwater pump from an emergency diesel generator is possible, provided that the switchover is a manual operation as discussed below.
2.
Provide a detailed description of how to power the motor-driven pump from an emergency diesel generator.
Respons e: The motor-driven auxiliary feedwater pump can be powered from emergency diesel generator 1 by opening breaker 252-103 on the 12-kV bus H1 and J
' closing breakers 152-101 and 152-501. This will
Attachment Page four parallel the non-Class 1E bus A5 with the Class IE bus A1.
The motor-driven auxiliary feedwater pump is powered from bus A5 through breaker 152-510.
The emergency diesel generator provides power to the bus Al through breaker 152-108.
Similarly, the motor-driven auxiliary feedwater pump can be powered from emergency diesel generator 2 by opening treaker 252-203 on the 12-kV bus, H2, and closing breakers 152-201 and 152-601 on buses A2 and A6 respectively, and finally ' energizing bus A5 by closing the Nas tie breaker 152-506. Emergency diesel generator 2 provides power to bus A2 through breaker 152-208.
3.
Discuss the capability of the emergency diesel generator to start the motor-driven pump.
Response
The motor-driven auxiliary feedwater pump will add approximately 1,000 kW to the emergency diesel generator loading af ter the motor has started. In addition, there will be 100 kVA of load due to the excitation impedance of the unit's substation -trans-former, which cannot be disconnected, and possibly 200 kW of load from the pressurizer heaters, which can be disconnected. There are approximately 3,400 kW of various safe shutdown loads on the emergency diesel generator during a loss of AC power.
The total load af ter starting the auxiliary feedwater
- pump would be approximately 4,500 kW.
The FSAR states that.the emergency generator output is rated as follows:
a.
The annual continuous rating (8,760-hr) is 4,418 kW.
b.
The 200-hr rating is. 4,920 kW.
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. Based upon these : ratings, we could not operate -he motor-driven auxiliary feedwater pump from the diesel generator for an indefinite period of time, assuming all the loads are on the same emergency power bus.
In order to start the motor-driven auxiliary feed-water pump, both the A5 'and Al buses Tdll have to be.
unloaded and the diesel generator dedicated to the start of the auxiliary feedwater pump. The purpose of dedicating the diesel. generator to the auxiliary.
feedwater pump is due to the high starting current of the motor '(IRA, locked-roter amperes), which is 5.35 times the normal operating current (FLA, full--
load amperes).
Attachment Page five In order to clear the bus for starting of the motor-driven auxiliary feedwater pump, all ESF loads that are required for normal shutdown must be operated from the remaining emergency diesel generator.
4a.
Present additional justification for manual alignment to emergency power.
Response
1.
The emergency diesel generators cannot provide enough power to start the electrical auxiliary feedwater pumps and carry ESF loads simultaneously.
2.
Safety concerns do not allow for automatic energiza-tion of the non-ESF buses from the ESF switchgear.
4b.
Present additional justification for manual starting from a reliability standpoint.
Response
Due to the high starting current (LRA) of the motor, all of the capability of the diesel generator is required for starting; theref ore, no additional loads will be allowed on either the ESF or non-ESF buses powered by that diesel generator. Only after the auxiliary feedwater pump has started may the ESF loads be brought online as required. Since manual operations are required and since the motor-driven pump itself is not safety-related, reliability gains from automatic starting on an emergency power supply j
will be negated.
An update of the progress that has been made_with the auxiliary feedwater system modifications _was also requested. In addition to the the afore-mentioned modifications, the condensate storage tank level instrumentation and alarm switches, as described in our December 31, 1979 and July 1, 1980 responses to Additional Short-Term Recommendation No. 1, have been installed and are now in service. The low suction pressure trips, as described in our December 31, 1979 and July 1,1980 responses to Long-Term Recommendation GL-4 have also been installed and are in service. The non-safety-related electric motor-driven pump has been installed and is powered from a non-ESF bus.
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