ML19210C747
| ML19210C747 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/07/1979 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7911200043 | |
| Download: ML19210C747 (31) | |
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o November 7, 1979 Docket Nos.: 50-317 50-318 Mr. A. E. Lundvall, Jr.
Vice-Presijent - Supply Baltimore Gas & Electric Company P. O. Box 1475 Baltimore, Maryland 21203
Dear Mr. Lundvall:
SUBJECT:
NRC REQUIREMENTS FOR AUXILIARY FEEDWATER SYSTEMS AT CALVERT CLIFFS NUCLEAR PLANT UNITS 1 AND 2 The purpose of.this letter is to advise you of our requirements for the auxiliary feedwater.;ystems at the subject facility. These reqcirements were identified during the course of the NRR Bulletins and Orders Task Force review of operating reactors in light of the accident at Thrae Mile Island, Unit 2.
8 to this letter identifies each of the requirements applicable to the subject facility. These requirements are of two types, (1) generic requirements appi?.able to most Combustion Engineering-designed operating plants, and (2) -lani-specific requirements applicable only to the subject facility. Enclosure 2 contains a generic request for additional information regarding auxiliary feedwater system flow requirements.
The designs and procedures of the subject facility should be evaluated against the applicable requirements specified in Enclosure 1 to determine the degree to which the facility currently conforms to these requirements.
The results of this evaluation and an associated schedule and commitment for implementation of required changes or actions should be provided for NRC staff review within thirty days of receipt of this letter. Also, this schedule should indicate your date for submittal of information such as design changes, procedure changes or Technical Specification changes to be provided for staff review. You may also provide your response to the items in Enclosure 2 at that time.
In addition to the requirements identified in this letter, other requirements which Tay be cpplicable to the subject facility are expected to be generated by the Bulletins and Orders Task Force. Such requirements are those resulting from our review of the loss-of-feedwater event and the small break loss-of-coolant acc-ident as described in the Co.abustion Engineering report CEN-lla-P (Amendment 1-P) 1372 069 79112 00 0h 3
Mr. A. E. Lundvall, Ji. entitled, " Review of Small Break Tran:,1ents in Combustion Engineering Nuclear Steam Supply Systems." Our specific concerns include systems reliability (other than the auxiliary feedwater system), analyses, guidelines and procedures for operators, and operator training.
We plan to identify, in separate correspondence, the requirements resulting from the additional items from the Bulletins and Orders Task Force review.
Sincerely, N
'c a e G.
1sen ut, Ac ing Director Division of Operating Reactors Office of Nuclear Reactor Regulation
Enclosures:
As stated cc w/ enclosures:
See next page 1372 070
Baltimore Gas & Electric Company cc:
James A. Biddison, Jr.
Mr. R. M. Douglass, Manager General Counsel Quality Assurance Department G and E Building Room 923 Gas & Electric Building Charles Center P. O. Box 1475 Baltimore, Maryland 21203 Baltimore, Maryland 21203 George F. Trowbridge, Esquire Shaw, Pittnan, Potts and Trowbridge 1800 M Street, N.U.
-Washington, D. C.
20036 11r. R. C. '_. Ol son caltimore Gas and Electric Company Room 922 - G and E Building Post Office Box 1475 Baltimore, Maryland 21203 Mr. Leon B. Russell, Chief Engineer Calvert C1.itfs Muclear Power Plant Baltimore Gas and Electric Company Lusoy, fiaryland 20657 Bechtel Power Corporation ATTH:
Mr. J. C. Judd Chief Nuclear Engineer 15740 Shady Grove Road Gaithersburg, Maryland 20760 Combustion Engineering, Inc.
ATTH: Mr. P. W. Kruse, Manager Engineering Services Post Office Box 500 Windsor, Connecticut 06095 Calvert County Library Prince Frederick, Maryland 20678
.i 1372 07'l
ENCLOSURE 1 X.2 (C-E)
CALVERT CLIFFS UNITS 1 & 2 AUXILIARY FEEDWATER SYSTEM X.2.1 SYSTEM DESCRIPTION X.2.1.1 Configuration - Overall Desian Figure 1 is a simplified diagram of the Calvert Cliffs Unit 1 auxiliary feedwater system (AFWS).
The Calvert Cliffs Unit 2 AFWS is identical to that of Unit 1.
Basically, the AFWS is a manually operated system that includes two steam turbine-driven pumps, each of whicn can deliver 700 gpm at 1100 psia. Both pumps are located in the auxiliary feedwater pump room.
The normal water supply to each pump is from Condensate Storage Tank i
No. 12 (CST No. 12), via a common ~line feeding a branch line to each pump.
Flow from each pump discharges into a branch line feeding a common line which in turn branches to each of two steam generators (SG).
AFWS flow is controlled by controlling pump speed and by regulating flow through a normally closed (NC) air-operated control valve in the feed line to each SG.
Each NC air-operated control valve fails open on loss of air, and each can be bypassed by a loop that includes a normally closed manually operated valve.
AFWS water can be obtained from five source.;. 'The primary water source for both units is CST No. 12 which has a 350,000 gallon capacity, 300,000 gallons of which are dedicated to the AFWS for both units.
The licensee stated that this amount of water can cool down both units and will last 1372 072
. six to ten hours, depending on the accident or transient that caused the need for AFWS operation.
The normal source of AFWS water flows from CST No. 12 through two normally open manually operated valves and a check valve in a common line which branches to the two pumps.
This source of water is designed to seismic Category I requirements and is protected against tornado missiles. The other sources of water are neither designed to seismic Category I requirements nor protected against tornado missiles.
The secondary sources of water consist of two-350,000,allon anks, CST No. 11 and CST No. 21 for Unit 1 and Unit 2, respectively.
Each tank is designed to serve its associated AFWS, without any cross-connection to the other tank, via a single line.
This line includes two normally closed manually-operated valves, and is connected to the common header that feeds both auxiliary feedwater pumps.
Although none of this water is dedicated for AFWS service, the licensee estimates that it would take about three to five minutes to line-up either tank to its respective AFWS, if required.
Three additional sources of water are:
(i) the 350,000 gallon deminer-alized water tanks; (ii) the two-500,000 gallon pretreated water storage tanks, of which 600,000 gallons are dedicated for fire protection usage; (iii) the well water system.
The licensee estimates that it would take approximately fifteen minutes to manually align the 350,000 gallon demineralized water tanks to CST No. 12.
The licensee also estimates that it would take approximately thirty minutes to connect the pretreated water storage tanks to the demineralizer system and that it would reouire approximately one hour if the demineralizer system is bypassed.
In either case, 1372 073
. the pretreated water storage tanks would be connected to CST No. 12, in which case the licensee estimates that all of the above tanks would provide for more than ten hours of AFW supply.
The well water system has a pumping capability of 966 gpm, and automatically (or manually, if required) replenishes the pretreated water tanks whenever they reach a low level.
The ability to maintain the AFW system function following certain postulated pipe breaks in the main steam, main feedwater and auxiliary feedwater piping systems was evaluated.
In the event of feedwater line breaks inside or outside containment or main steam line breaks downstream of the main steam isolation valve (MSIV), acceptable AFWS capability can be retained by feeding the intact steam generator, provided the control valve to the affected steam generator is maintained closed.
However, if a steam line break occurs upstream of the MSIV concurrent with a single active failure, or if a steam line break occurs in the common header to the two AFW pump turbines, even without an active failure, potential problems could result in the containment penetration area.
In the former case, if the steam inlet motor operated valve (MOV) from the unaffected steam generator to the turbine-driven auxiliary feedwater pump fails to open, loss of AFWS function will result. This AFWS function can be restored by manually opening the bypass valve around the affected M0V, thereby admitting steam to the turbine-drive AFW pumps and restoring AFWS function.
This manual action is possible since the bypass valves have operator extensions which extend into the adjacent room.
In the latter case, the AFW pump room must be vented and cooled to permit access for isolating the break 1372 074
. and manually supplying steam to the AFW pump turbines from the other unit or from the auxiliary steam generator.
The licensee estimates that these emergency actions can be accomplished in approximately thirty minutes.
Except for the pumps, the AFWS equipment is not qualified for operation in the pipe break environment.
Pipe breaks at two locations in the AFWS were considered:
(1) at the steam generator, and (2) in the common discharge header between the pumps and the steam generators (the worst case break).
In the former case, manual action (e.g., closing the normally open valve in the affected line) can be taken to assure flow to the unaffected steam generator.
The licensee estimates that it would take approximately three minutes to perform the required valve operation (s).
In the latter case, however, lois of feedwater function will result and persist until the break itself is repaired.
Depending on the initial plant conditions and the event that causes the need for the AFWS, the licensee estimates that the steam generators would boil dry in approximately thirty minutes if the AFWS is not actuated.
X.2.1.2 Components - Design and Classification The licensee stated that the components and equipment of the AFWS were designed and classified in accordance with the following table.
1372 075
. Environmental Design Seismic Comoonent/ Equipment Qualification Classification Category Pumps & Turbine High Energy Safety Related I
Pipe Break Valves / Actuators Ambient Piping Main Steam System up to MSIV Condensate Storage Tank No. 12 Condensate Storage Non-Safety Non-Seismic Tanks Nos. 11 & 21 Related Demineralized Water Tank Pretreated Water Tank Deep Well System Controls and Instrumentation X.2.1.3 Power Sources Steam to drive the AFWS turbine-driven pumps is obtained from the steam generators.
Each steam generator can supply steam to either or both steam turbine-driven pumps from its main steam line through a normally closed motor operated valve which fails as-is or a normally closed manual bypass valve into a common header.
Each AFW pump takes steam from the common header through a normally open manual valve, a check valve, a DC operated normally open stop valve, and an air operated normally closed throttle valve.
An alternate source of steam can be obtained from the steam generators of the other unit or from steam generated by the auxiliary steam generator, which uses an oil fired boiler (aux, stm. gen.). The 1372 076
. a'Iternate. sctrce of steam is routed through a normally locked closed manual valve connected between the check valve and stop valve on each pump steam supply line.
The two motor operated steam turbine pump inlet valves are powered from separate emergency AC buses. The turbine control valve and the AFWS flow control valve are air operated fail open valves.
The turbine stop valves are powered from the DC buses, and fail in the open position.
All control and instrumentation power is from emergency buses which can be energized from the diesel generators.
Upon loss of all station AC, local manual action is required to start the system by opening the steam inlet MOV's.
X.2.1.4 Instrumentation and Controls X.2.1.4.1 Controls The following controls are located in the Control Room:
1.
Hand indicating controllers for a.
Turbine Control (throttle) Valve b.
AFW: Regulating Valve 2.
Motor Operated Valves - Open/Close 3.
Turbine Trip All controls except the motor operated valve controls are also located at the Remote Shutdown Panel /AFWS Pump Room.
1372 077 X.2.1.4.2 Information Available to the Operator The following alarms are located in the control room:
1.
Common Alarm Low Pump Suction and Discharge Pressure 2.
Condensate Tank Low Level Alarms a.
Common Alarm Tank 11 & 12 b.
Common Alarm Tank 12 & 21 3.
Steam Generator Low Level Alarms No alarms are located at the Remote Shutdown Panel or the local stations.
The following indicators are located in the control room:
1.
AFW Flow Indicator - one per steam generator 2.
Steam Generator Level 3.
Condensate Storage Tanks' Level Indication 4.
Valve Position Indication for a.
Motor Operated Inlet Steam Valve b.
Turbine Control Valve c.
AFW Regulating Valve d.
Turbine Stop Valve 5.
Pump Discharge Pressure 6.
Steam Line Pressure 7.
Pump Suction Pressure (Common) to be Removed The following indicators are located at the Remote Shutdown Station:
1.
Steam Generator Level 2.
CST Level 1372 078
. 3.
AFW Regulating Valve Position Indicator 4.
Pump Discharge Pressure 5.
Steam Line Pressure X.2.1.4.3 Initiating Signals for Automatic Operation Since the system is a manually initiated system this section is not appli-cable.
Manual AFW initiation is 'ay a semi-dedicated operator in the control room following any reactor trip.
The semi-dedicated operator means that the operator has other duties in the control room until that time when the AFWS is needed, then he is dedicated 100% to operate, control and monitor the system.
X. 2.1. 5 Testing The pumps are testeo on a monthly basis in a recirculating mode of operation for total dynamic head and vibration, and for bearing tempera-tures at each refueling. All non-manusi valves are stroked and timed monthly. The instrumentation at the remote shutdown panel is checked monthly.
The normally closed or opened manual valves are not stroked.
When the system has been down for maintenance, the normal monthly tests are performed prior to the system being restored to service.
X.2.1.6 Technical Specifications Tne following are the technical specifications for the plant.
1372 079
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AUXILIARY FEEDWATER SYSTEM LIMITING CONDITION FOR OPERATION 3.7.1.2 At least two steam turbine driven steam generator auxiliary feedwater pumps and associated flow paths shall be OPERABLE.
APPLICABILITY: MODES 1, 2 and 3.
ACTION:
With nne auxiliary feedwater pump inoperaole, restore at least two auxiliary feedwater pumps to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
SURVEILLANCE REQUIREMENTS 4.7.1.2 Each auxiliary feedwater pump shall be demonstrated OPERABLE:
a.
At least once per 31 days by:
1.
Verifying that the steam turbine driven pump develops a Total Dynamic Head of > 2800 ft. on recirculation flow when the secondary steam supply pressure is greater than 800 psig.
2.
Verifying that each valve (manual, power operated or automatic) in the flow path that is not locked, sealed, or otherwise secured in position, is in its correct position.
1372 080
. CONDENSATE STORAGE TANK LIMITING CONDITION FOR OPERATION 3.7.1.3 The No. 12 condensate storage tank (CST) shall be OPERABLE with a minimum contained water volume of 150,000 gallons per unit.
APPLICABILITY: MODES 1, 2 and 3 ACTION:
With the No.12 condensate storage tank inoperable, within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> either:
a.
Restore the CST to OPERABLE status or be in HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, or b.
Demonstrate the OPERABILITY of the No. 21 condensate storage tank as a backup supply to the auxiliary feedwater pumps and restore the No. 12 condensate storage tank to OPERABLE status within 7 days or be in HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
SURVEILLANCE REQUIREMENTS 4.7.1.3.1 The No. 12 condensate storage tank shall be demonstrated OPERABLE at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by verifying the contained water volume is within its limits when the tank is the supply source for the auxiliary feedwater pumps.
4.7.1.3.2 The No. 21 condensate storage tank shall be demonstrated OPERABLE at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by verifying that the tank contains a minimum of 150,000 gallons of water and by verifying that the flow path 1372 081 for taking suction from this tank is OPERABLE with the manual valves in this flow path open whenever the No. 21 condensate storage tank is the supply source for the auxiliary feedwater pumps.
X.2.2 RELIABILITY EVALUATION RESULTS X.2.2.1 Dominant Failure Modes Failure modes of the AFWS were assessed for three loss of main feedwater transients. The dominant failure modes for each transient type are discussed below.
Loss of Main Feedwater (LOFW) with Offsite Power Available There are two dominant failure modes of the AFWS for this transient, both of which are related to human errors.
The first human error is failure of the operator to manually initiate the AFWS.
Upon a demand for the AFWS, the operator has approximately 30 minutes to actuate AFWS and prevent steam generators from boiling dry, depending on the cause of the transient.
Thus, the human error is the failure to actuate AFWS within this time period.
The second human error is related to the inadvertent closure of either of two manual valves in the single condensate storage tank supply line to the AFWS pumps.
Such an inadvertent closure could result from a number of causes, e.g., personnel error in closing the wrong valve during a test procedure, or an error in failing to reopen the valve after maintenance in adjoining parts of the AFWS.
Coupled 1372 082.
with this error is the failure of the operator to reopen the valve before damage to the pumps occurs following an AFWS demand. The combi-nation of these errors results in an AFWS failure.
Loss of MFW with Only Onsite AC Power Available This transient is very similar to the transient discussed above.
Additional failure modes related to the onsite AC power system were considered; however, these did not have a significant impact. As such the dominant failure modes discussed above are also considered to the applicable for this transient.
Toss of MF4 with Only DC Pcwer Available In this transient no AC pcwer, either onsite or offsite, is available.
Because of certain AC dependencies, the dominant failuna mode is assessed to be the failure of the operater to manually open one of the two steam admissicn valves to the pump turbine within approximately thirty minutes after the transient. These valves are normally closed motor-operated valves that normally receive power from either the offsite AC pcuer syctem or the onsite (diesel-generator) AC power system. Since neither of these sources is available in this transient, local manual opening of one of the valves would be required.
1372 083 X.2.2.2 Principal Dependencies The principal dependency identified for this AFWS system is that related to human action requirements.
For each transient discussed here, human errors are the dominant AFWS failure modes, Two additional potential dependencies have been noted for the Calvert Cliffs AFWS, both resulting from the physical location of equipment within the plant.
These are:
1.
Location commonality of AFWS pumps.
Both AFWS turbine pumps (and some associated valving) are located in a relatively small room sealed with watertight doors.
Because of this close proximity of redundant equipment, there exists the potential for total AFWS failure resulting from flooding, missiles, etc.,
caused by failures within one train or from external causes.
(See Recommendations) 2.
Location commonality of steam-admission valves.
Both steam-admission valves for the AFWS pump turbines are located in a common area, the main steam line penetration room.
Normal conditions in this area are high temperature and high humidity; thus, there exists some potential for environmentally-caused common mode failures.
In addition, because the main steam lines are located just above these valves, the potential environmentally-caused failure of these valves after a steam line break, when AFWS is needed, requires further investigation.
(See Recommendations) 1372 084
X.2.3 Recommendations for this Plant The short-term recommendations (both generic, denoted by GS, and plant-specific) identified in this section represent actions to i.aprove AFW system reliability that should be implemented by January 1, 1980, or as soon thereafter as is practicable.
In general, they involve upgrading of Technical Specifications or establishing procedures to avoid or mitigate potential system or operator failures.
The long-term recommendations (both generic, denoted by GL, and plant specific) identified in this section involve system design evaluations and/or modifications to improve AFW system reliability and represent actions that should be implemented by January 1, 1981, or as soon as thereafter as is practicable.
X.2.3.1 Short Term 1.
Recommendation GS The licensee presently, by administrative procedure, locks open single valves or multiple valves in series in the AFW system pump suction piping and locks open other single valves or multiple valves in series that could interrupt all AFW flow. Monthly inspection should be performed to verify that these valves are locked and in the open position. These inspections should be proposed for incorporation into the surveillance recommendations of the plant Technical Specifica-tions. See Recommendation GL-2 for the longer-term resolution of this concern.
2.
Recommendation GS Emergency procedures for transferring to alternate sources of AFW supply should be available to the plant operators.
These procedures should include criteria to inform the operator when, and in what order, the transfer to alternate water sources should take place. The following cases should be covered by the procedures:
$.b ? []@ S
,f d' The case in which the primary water supply is not initially available. The procedures for this case should include any operator actions required to protect the AFW pumps against self-damage before a water flow is initiated, and, The case in which the primary water supply is being depleted.
The procedure for this case should provide for transfer to the alternate water sources prior to draining of the primary water supply.
3.
Recommendation GS 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 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 s hall 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 one 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 an on-off mode until alternating current power is re. stored.
Adequate lighting powered by direct current power sources and communications 1372 086
/
. at local stations should also be provided if manual initiation and contorl of the AFW system is needed.
(See Recommendation GL-3 for the longer-term resolution of tr.is concern.)
4.
Recommendation GS The licensee should confirm flow path availability of an AFW system flow train that has been out of service to perform periodi_c testing or maintenance as follows:
Proceduret should be implecented to require an operator to determine that the AFW sys:cm valves are properly aligned and a second operator to indepen:ently verify that the valves are properly aligned.
The licensee should proposs Technical Specifications to assure I
that prior to plant startu: following an extended cold shutdown, a flow test would be perfo med to verify the normal flow path from the primary AFW systen water source to the steam generators.
The flow test should be co-ducted with AFW system valves in their normal alignment.
5.
Recommendation GS The licensee should install a system to auto-matically initiate the AFWS, This system need not, in the short-term, be safety-grade; however, it should meet the criteria listed below, which are similar to Item 2.1.7a of flVREG-0578. For the onger term, the automatic initiation signals and circuits should be upgraded to meet safety-grade requirements as indicated in Recommendation GL-1.
1372 087
. The design should provide for the automatic initiation of the auxiliary feedwater system flow.
The automatic initiation signals and circuits should be designed so that a single failure will not result in the loss of auxiliary feedwater system function.
Testability of the initiating signals and circuits should be a feature of the design.
The initiating signals and circuits should be powered from the emergency buses.
Manual capability to initiate the auxiliary feedwater system from the control room should be retained and should be implemented so that a single failure in the manual circuits will not result in the loss of system function.
The alternating current motor-driven pumps and valves in the auxiliary feedwater system should be included in the automatic actuation (simultaneous and/or sequential) of the loads to the emergency buses.
The automatic initiation signals and circuits should be designed so that their failure will not result in the loss of manual capability to initiate the AFW syttem from the control room.
6.
Recommendation - The licensee should propose modifications to Technical Specifications to require that manual valves that are normally closed or open will be tested periodically.
1372 088
/
. X.2.3.2 Additional Short-Term Recommendations The following additional short-term recommendations resulted from the staff's Lessons Learned Task Force review and the Bulletins and Orders Task Force review of AFW systems at Babcock & Wilcox-designed operating plants subsequent to our review of the AFW systems designs at W-and C-E-designed operating plants.
They have not been examined for specific applicability to this facility.
1.
Recommendation - The licensee should provide redundant level indications and low level alarms in the control room for the AFW system primary water supply to allow the operator to anticipate the need to make up water or transfer to an alternate water supply and prevent a low pump suction pressure condition from occurring.
The low level alarm setpoint should allow at least 20 minutes for operator action, assuming that the largest capacity AFW pump is operating.
2.
Recommendation - The licensee should perform a 72-hour endurance test on all AFW system pumps, if such a test or continuous period of operation has not been accomplished to date.
Following the 72-hour pump run, the pumps should be shut down and cooled down and then restarted and run for one hour.
Test acceptance criteria should include demonstrating that the pumps remain within design limits with respect to bearing / bearing oil temperatures and vibration and that pump room ambient conditions (temperature, humidity) do not exceed environmental qualification limits for safety-related equipment in the room.
1372 089
. 3.
Recommendation - The licensee should implement the following require-ments as specified by Item 2.1.7.b on page A-32 of NUREG-0578:
" Safety grade indication of auxiliary feedwater flow to each steam generator shall be provided in the contrcl room.
The auxiliary feedwater flow instrument channels shall be powered from the emergency buses consistent with satisfying the emergency power diversity requirements for the auxiliary feedwater system set forth in Auxiliary Systems Branch Technical Position 10-1 of the Standard Review Plan, Section 10.4.9."
4.
Recommendation - Licensees with plants which require local manual realignment of valves to conduct periodic tests on one AFW system train, and there is only one remaining AFW train available for operation should propose Technical Specifications to provide that a dedicated individual who is in communication with the control room be stationed at the manual valves.
Upon instruction from the control room, this operator would realign the valves in the AFW system train from the test mode to its operational alignment.
X.2.3.3 Long-Term Long-term recommendations for improving the systems are as follows:
1.
Recommendation - GL Licensees with plants having a manual starting AFW system should install a system to automatically initiate the AFW system flow. This system and associated automatic initiation signals 1372 090
. should be designed and installed to meet safety grade requirements.
Manual AFW system start and control capability should be retained with manual start serving as backup to automatic AFW system initiation.
2.
Recommendation - GL Licensees with plants in which all (primary and alternate) water supplies to the AFW systems pass through valves in a single flow path should install redundant parallel flow paths (piping and valves).
Licensees with plants in which the primary AFW system water supply passes through valves in a single flow path, but the alternate AFW system water supplies connect to the AFW system pump suction piping downstream of the above valve (s) should install redundant valves parallel to the above valve (s) or provide automatic opening of the valve (s) from the alternate water supply upon low pump suction pressure.
The licensee should propose Technical Specifications to incorporate appropriate periodic inspections to verify the valve positions.
3.
Recommendation - GL At least one AFW system pump and its associated flow path and essential instrumentation should automatically initiate AFW system flow and be capable of being operated independently of any alternating current power source for at least two hours.
Conversion of direct current power to alternating current is acceptable.
}372
. 4.
Recommendation - The motor operated steam inlet valves and other equipment affected by the environmental effects of the main steam and feed line breaks discussed in section 2.1.1 and 2.2.4 should be qualified to the environmental conditions that will be present.
5.
Recommendations - The licensee should evaluate the following concerns:
a)
The AFW pump discharge lines and turbine driven AFW steam supply lines combine into different single lines through which all AFW water or steam must flow.
(See Figure 1).
A pipe break in either of these single flow paths would cause loss of the entire AFW function.
b)
The Calvert Cliffs AFW systems do not meet the high energy line break criteria in SRP 10.4.9 and Branch Technical Position 10-1; namely, that the AFW system should maintain the capability to supply the required flow to the steam generator (s) assuming a pipe break anywhere in the AFW pump discharge lines concurrent with a single active failure.
The licensee should evaluate the postulated pipe breaks stated above and (1) determine any AFW system design changes or procedures necessary to detect and isolate the break and direct the required feedwater flow to the steam generator (s) before they boil dry or (2) describt how the plant can be brought to a safe shutdown condition by use of other systems which would be available following such postulated events.
1372 092
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E'ICWSURE 2
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s EASIS FOR AUXILIAKI ru.udATER SYSE FTW FIOUIFIMErrS As a msult of scent staff reviews of operating plant auxiliary feedwater systems (ATdS), the 7taff concludes that the design bases and c-iteria provided by licensees fcr establishing ATdS mquirerents for ficw to the stea.1 generator (s) to assure ade-quate m.cval of reactcr decay heat are not well defined cr docmted.
'de require that you provide the fellcwing ATdS ficw design basis inferration as appli-cable to the design basis transients and accident ecnditions fer your plant.
Identify the plant transient and accident ecnditiens considend in estab-1.
a.
lishing ATdS ficw requirements, including the folloaing events:
- 1) Irss of P.ain Feed (LTd)
- 2) LvTd w/lcss of offsite AC pcwer
- 3) LTd w/ loss of offsite and cnsite AC pcuer
- 4) Plant cooldcun
- 5) Turbine trip with and without bypass
- 6) Fain steam isolation valve closure
- 7) Fain' feed line break
- 8) Main steam line break 9)
Srall break IICA
- 10) Other transient or accident conditiens not listed above.
Describe the plant protection acceptance criteria and correspcnding techni-b.
cal bases used fcr each initiating event identified abcVe. The accep a ce criteria should address plant limits such as:
- M_axima RCS pressure (PORV cr sa#ety valve actuation)
- Fuel te.perature er darage lirits (rRS, PCT, raxirm "uel central temparan
- RCS cooling rare lirit to avoid excessive ecclant sh-inkage
- Mini== steam generator level to assure su'ficient steam generator heat t a fer surface to re.cva decay. heat and/cr cocidcun de prirary system.
1372 094
. s rescribe the analyses and assumptions and ccrresponding tectical justificatica 2.
used with plant conditiens considered in 1.a. above including:
Maxi.a.:n reactor pcwer (including instrrent errer alicwance) at the ti e of a.
the initiating transient or accident.
b.
Tire delay frca initiating event to reacter trip.
Plant parameter (s) which initiates ATdS flev 'nd ti a delay between in? tiat-c.
ing event and introhetion of AEdS ficw i' 'o steam genera:cr(s).
d.
Minimum steam generator water level when initiating event occurs.
Initial steam generator water inventory and depletica rate before and a#ter e.
ATdS ficw cc::rences - identify reacter decay heat rete used.
Maximum pressure at which steam is released fmm steam generatcr(s) and agains-f.
which the A2d pump must deve'..cp sufficient head.
Mini. n number of steam generators that must receive AZA ficw, e.g., 1 of 2, g.
2 of 47 h.
RC ficw condition - continued operation of RC pumps or natural cimulatien.
- i. Maximum Afd inlet temperature.
- j. Follcwing 'a postulated steam er feed line break, tire delay assumed to isolate break and direct AF4 flcw to intact steam generator (s). AFd pump flow capaci:
allcsance to accco:date the tire delay and maintain minimum steam generator water level. Also idectify credit taken for primary system heat reroval due to bicwdcwn.
k.
Volume and Taxin:n temperature of water in rain feed lines between steam generator (s) and AEdS connectica to main feed line.
1.
Operating ccaditien of steam genera:Or nc:ral bicudown following initiating event.
Prirrj and secondary system water and metal sensible heat used for coolder and AFd ficw sizing.
n.
Ti e at het standby and time to crldr t ?.CS :: ?5 (cr SCS) sistem cut in te perature to size AJ4 water scurce inven crf.
1372 095
. s 3.
Verify that the iuW pumps in your plant will supply the necessary ficra to the steam generator (s) as deterdned by iters 1 and 2 above considering a single failure. Identify the rargin in sizing the pump ficw to allcw for pt=p recir-culation ficw, seal leakage and pump wear.
1372 096~
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