ML19259D286
| ML19259D286 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 09/11/1979 |
| From: | Latorre V YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML19259D281 | List: |
| References | |
| NUDOCS 7910170569 | |
| Download: ML19259D286 (23) | |
Text
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e SELECTED ISSUES PROGRAM TECHNICAL EVALUATION OF THE ELECTRICAL, INSTRUMENTATION, AND CONTROL DESIGN ASPECTS OF THE. LOW TEMPERATURE OVERPRESSURE PROTECTION SYSTEM FOR THE MAINE YANKE4 NUCLEAR F0WER PLANT by V. R. Latorre B. G. Mayn*
I163 006
- EG&G, Energy Measurements Grouc, San Raracn Oceratiens 7910170
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This report documents the technical evaluation of the electrical, instrunentation, and control design aspects for the icy temperature over-pressure protection system of na Maine Yankee nuclear power plant. Design basis c:iteria used to evaluate the acceptability of the system included operator action, system testability, single failure criterion, and seismic Category I and IEEE Std-279-1971 criteria. This report is suppli <i as part of the Selected Electrical, Instrumentation, and Control Systems Issues Support Program being cond acted for the U. S. Nuclear Regulatory Comission by Lawrence Livermore Laboratory.
e i163 007 O
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TECHNICAL EVALUATION OF THE ELECTRICAL, INSTRUMENTATION, AND CONTROL DESIGN, ASPECTS OF THE LOW TEMPERATURE OVERPRESSURE PROTECTION SYSTEM FOR THE MAINE YANKEE NUCLEAR POWER PLANT 1.
INTRODUCTION By letter to the Mrine Yankee Atomic Power Cmipany (MYAPCO) fated August 11, 1976, the U. S. Nuclear Regulatory Comission (NRC) requested an evaluation of system designs to detennine susceptibility to overpressuriza-tion events and an analysis of these possible events, and proposed interim and pennanent modifications to the systens and procedures to reduce the likelihood and consequences of such events.
By letter dated December 2, 1976 and subsequent letters (refer to the Appen' dix), the Maine Yankee Atanic Power Company submitted the additional information requested by the NRC staff, including the adninistrative operating procedures and the pro-posed icw tenperature overpressure mitigating system.
The syst em harcware
'.ncludes sensors, actuating mechanisms, alarms, and valves to prevent a
reactor coolant system transient from exceeding the pressure and tempera-tuce limits of the Technical Specifications for Maine Yankee as required by the Code o' Federal Regulaticns, Title 10, Part 50 (10 'CFR 50), Appendix G.
9 The pur;ose of this report is to evaluate the electrical, instru-mentation, and control (EI&C) aspects of the Licensee's equipment and procedures b 3ed on the information provided (refer to the Appendix), and to define how well they meet the criteria established by NRC as necessary to prevent unacceptable overpressurization events.
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2.
EVALUATION OF MAIN 2 YANKEE
2.1 INTRODUCTION
Review of the Maine Yankee low temperature overpressure protection system design by MYAPC0 was begun in 1976 at NRC's request. The proposed
' overall approach to eliminating overpressure events incorporates admin-istrative, procedural, and hardware controls, with reliance upon the plant operator for the principal line of defense.
Preventive administrative /
procedural measures include:
(1)
Procedural precautions.
(2)
Deenergization (power removed) of essential components which are not required to be operable during the cold shutdown mode of operation.
(3)
Maintenance of a non-water-solid reactor coolant system condition whenever possi';1e.
(4)
Incorporation of a low pressure relief setpoint for the existing sol enoid-ocerated rel ief val ve (SCRV) control logic, and the use of the residual heat re-moval (R'~l) system.
The design basis criteria that were applied in evaluating the acceptability, of the electrical, instrunentction, and control aspects of low temperature overpressere mitigating system (CMS) are as follows:
(1)
Ocerator Actien.
No credit for operator action is taxen until ten minutes after the operator is aware, through an action alar a, that an over;ressere trans-ient is in progress.
(2)
Sincie r ilure Criterion.
Tne CMS shall be designed a
to protec: tne reac:or vessel given a single failure whien is in addition to the failure that initiated the pressure transient.
l163 009
i (3)
Testability.
The OMS must be testable on a periodic basis prior to dependence on the OMS to perfonn its function.
(4)
Seismic Category I and IEEE Std-279-1971 Criteria.
N OMS snould satisfy botn the seisnic Category I and cEE Std-279-1971 criteria.
The basic objective is chat the CMS should not be vulnerable to a failure mode that wuld both initiate a pressure transient and disable the low temperature overpressure mitigating system.
Events such as loss of instrunent air and loss of offsite power must be considered.
~
2.2 MYAPCO OVER;RESSIRE MITIGATING SYSTEM DESIGN The MYAPC0 overpressure mitigating system design information detailed in this section was derived from the references listed in the Appendix.
The MYAPCO design for the Maine Yankee CMS is based on the use of tw pressurizer solenoid-operated relief valves (50RV's) alo,ig with tw passive spring-loaded safety valves (SV's) which are located on the suction line of the RHR system piping.
These valves, in conjunction with specific procedural controls, form the bases for the following conditions:
(1)
Each pressurizer 50RV will provida sufficient and redundant relief capacity to ensure that the reactor coolant system (RCS) pressure remains pelow 589 psig when the RCS temperature is below 220 F.
The pres-surize,r.CRV Icw pressure setpoint is 500 psig.
(2)
The tw RHR SV's together will prcvide sufficit.: and redundant rel ief caoacity to ensure that the RCS pressure remains gelow 539 osig when the RCS temcera-ture is below 220 F.
The RHR SV Icw pressure setpoint is 400 psig.
(3),
A 225 F temperature switch will be provided to ensure that the RHR-SV isolation valves and the pressurizer-SCRf isolation valves are open at temperatures belcw 225 F.
Valves that are not open will be annunciated on the main control board.
(4)
Additional assurance of preventing inadvertent bl ow-down at RCS tem::eratures above 3CO'F is provided by the inclusion of a 300*F ten::erature swittn.
This switch will ensure that the RHR-3V 'i sol ation v al ves are closed and tnat the pressuri::er 500."s have been 2-2 1163 010 es e = me me
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reset to the high setpoints required for nonnal plant operation.
Failure of the RER-SV isolatfor. valves to close or ' failure of the pressurizer 50RV's to be reset to the high setpoint will be annunciated on the rain control board.
The two pressurizer SORV's are equipped with a low pressure set-point feature.
This feature, when enabled by the operator by means of a key lock switch, causes each pressurizer 50RV to open when the pressurizer pressure reaches a setpoint of 500 psig.
In accordance with pl ant cooldewn procedures, the pressurizer SCRV's are set to the low pressure setpoint when the systan pressure is less than 450 psig.
This low p. essure setpoint is to be established prior 0
to decreasing the RCS tenperature below 220 F.
Plant operating procedures provide that normally the RHR system suction isolation valves are open below 220 F thereby making available the relief capacities of these two safety valves as reactor vessel overpress re protection devices.
An RHR interlock does exist, however, which prevents the opening of the isolation valves at all pressures in excess of 400 psig.
It is concluded, therefore,, that when the pre-*'tre is decreasing, the RHR SV's offer no overpressure protection until the pressure is reduced to 400 psig or below and the RHR-SV isolation valves are allowed to open.
For decreasing press'ures between 500 psig (pressurizer 50RV low setpoint) and 400 psig (RHR-SV maximun isolation valve opening pressure for decreasing RCS pressure), it appears that the overpressure protection system is vulnerable to an overpressure transient if the single failure criteria is applied and the pressurizer 50RV actuation circuitry fa s.
Although this is true, it should be enphasized that the MYApCO CMS will not be enabled unless the RHR-SV isolation valves are open, which implies that the pressure is equal to or less than 400 psig.
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2.3 EVALUATION OF MAINE YANIEE USING DESIGN BASIS CRITERIA Maine Yankee was evaluated under the guidanca of the four desi n 3
basis criteria stated in Section 2.1 of this evaluation,. and with specific attention given to various pertinent NRC staff positions resulting from these criteria.
Sections 2.3.1 through 2.3.4 are concerned with the four i
criteria.
2.3.1 Ooerator Action In each design basis transient analyzed, no credit for operator action was taken until 10 minutes after the initiation of the RCS over-pressurize transient and after the operator was made aware of the over-pressure transient by the low tenperature overpressure transient al am.
The crierion for operator action is consistent with that suggested at the recent meetings between pre:surized water reactor (PWR) Owners and the NRC:
1.e., when a plant is operated in accordance with established operating pre:edures, the protection afforded by nonnal operating procedures is a vital part of the overall plan for protection ag inst overpressurization.
In the analysis of postulated overpressure events presented in A, 'andix G,10 CFR 50, operator action to mitigate the consequences of the event are conservatively assuned not to occur for ten minutes after the event. The operator is alerted to a possible overpressure event by mean' of the impending transient and pressurizer 501V open alams on the master control ocard.
!n this analysis, it is seen that adhere'nce to normal operating procedures is the only requirement placed upon the operator to guarantee overpressure protection.
Although the above criterion has been established, there is no dependence on operatcr action after the ten-minute interval to mitigate the effects of an overpressurization event.
The pressurizer SCRY's and the nornally available capacility of the RHR SV's provide redundant protection from overpressurization in all the events analy:ed.
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2.3.2 Single Failure Criterion The NRC staff position requires that the OMS shall be designed to protect the reactor vessel given a single failure which,is in addition to the failure that initiated the pressure transient.
The NRC staff position also requires that the power supplies and power sources for the pressurizer SORV's be completely separate and distinct from those of the RHR-5V's.
The MYAPCO Maine Yankee CMS is intended to protect the reactor vessel given a single failure in addition to the failure that initiated the overpressure transient.
The single failure criterion has been applied to both the initiating events e,.d the means of mitigating the effects of these overpressurization events.
It was assumed that either a single equipent malfunction or a single erroneous operator cont., manipulation can ini-tiate each of the overpressurization events consider A. '
Protection against overpressurization eve'nts is provided by the two pressurizer SCRV's whose ccrabined capacity is sufficient to maintain the reactor coolant pressure below 589 psig at all temperatures below 0
220 F, asstraing the worst case event.
In addition, the RFR SV's provide redundant relief capacity whenever normal operating procedures require the RHR system tJ be open to the RCS.
Means have been empl oyed to provide the margin of protection afforded by the single failure criterion both in preventing.an avent ini-t1ation and in limiting the effects of an event once it is initiated.
The use of pressurizer 50RV's in cenjunction with RER SV's is an acceptable concept.
We conclude that the MYAPC0 Maine Yankee OMS does satisfy the NRC staff single failure criterion.
1163 013 2-s
2.3.3 System Testability The MIC staff position requires that the (NS, control circuitry fran the pressure sensor to the valve solenoid should be tested prior to each heatup or cooldown.
The RHR SV's and pressurizer SORV's should be tested during each refueling.
Deviations fran this criterien should be justified.
There are two aspects associated with the testability of the MYAPCO Maine Yankee OMS.
The first aspect is concerned with the pressurizer-SORV testing program for low pressure protection system oper-ability. These tests are as follows:
(1)
Verification of upstream isolation valves functioning once per cold shutdown.
(2)
Perfornance of a channel functional test of the con-trol circuitry from the pressure s'ensor to the valve solenoid once per refueling outage.
(3) perfonnance of a channel calibration of the pres-surizer pressure sensors once per 18 months.
The second aspect o' the testing progran involves the plant. tests during cold shutdcwn which could result in an RCS overpressurization above the minimun operating ' limit curves. These tests are as follows:
(1)
Actuation of the containment isolation system (CIS).
(2)
Actuation of the safety inj ection actuilor system (SIAS).
~
(3)
Flow testing of the high pressure safety injection (HPSI) punp.
(4 )
Testing of the CIS trip valve.
(5)
Calibration of the RHR interlock cimuitry.
1163 014 2-5
The following preventative measures have been instituted to prevent in-advertent RCS overpressurization during this testing:
(1)
The initial conditions for the CIS actuation test require that the chac}ing, letdown, and purification systems are secured prior to the test.
(2)
A procedural step in the SIAS actuation test closes the discharge valve on the charging (HPSI) punp to be tested prior to SIAS actuation.
The control switch for the other charging punp is in the " pull-to-lock" position.
(3)
The HPSI pump flow test is performed while flooding the refueling cavity wth the reactor vessel head removed.
(4)
The CIS trip valve test includes a caution statement, imediately preceding tne test stroking of the letdown CIS trip valve, that requires an alternate letdown path if the plant is in a water-solid condition.
(5)
The prerequisite section of the calibration procedure for the RHR interlock circuitry requires that the RCS is depressurized and does not require relief protec-tion (i.e., the reactor vessel head is removed or a pressurizer safety valve is removed for pressurizer venting).
When canponent testing is required which might cause an RCS pressure rise above the minimum pressere/termperature limit curves, the CMS will be operational onsistent with the RCS temperature consideration.
For the Maine Yankee nuclear power plant, each pressurizer SCRV can be isolated from the pressuri:er by means of an upstream isolation valve.
Once isolated, the solenoid-operated pilot actuator can be tested for operabili.ty prior to plant cooldewn.
Nonnal cperating procedures will be modified to require this test prior to plant cooldown for each refueling shutdown.
Since the Maine Yarikee nuclear pcwer plant uses two pressurizer SGtV's driven by one pressure transnitter plus the safety / relief valves installed in the RHR system, the NRC staf# position also acplies to the 2,HR system valves and control circuitry that are used in the low temperature CMS.
2-7 1163 015
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We conclude that the 'iYAPCC Maine Yankee CMS satisfies the EIaC testability criteria if the valves and control circuitry in the RHR system, which are used for overpressurizat'on mitigation, are tested in accordance with the NRC staff position stated at the beginning of this sections 2.3.4 Seismic Design and IEEE Std-279-1971 Criteria 2.3.4.1 Seismic Design Criteria.
The Licensee states that the Maine Yankee pressurizer 50RV's and RHR system safety valves have een designed to meet the requirements of seisnic Category I criteria.
'2.3.4.2 IEEE-279-1971 Critaria For the Maine Yankee nuclear power pl ant, t;he primary design purpose of the pressurizer SCRV during nomal plant operation is to provide the means by which an excess pressurizer pressure condition can be correct-ed without necessitating the opening of the safety-class mechanical safety valves.
This capability elimirites the consequential potential leakage condition in case the safety valves reset and reseal incorrectly. A second feature allows the operator, using a main control board-mounted switch, to manually energize (and open) the relief valve ar.t decrease system pressure in the pressurizer. A third feature, the " dual setpoint", was added during siginal systen design to provide a means of potential reactor vessel icw temperature overpressurization (LTO) protection.
This' existing dual set-point feature pemits the operator, using a.1ain control board-mounted permissive keylock switch, to arm the pressurizer-SCRV trip circuit for both nomal (2335 psig trip) ard LTO (500 psig tripl hlait operation.
The Licensee has stated that none of these three features con-stituted a recuirenent for a redundant safety class ele:trical actuation system and, therefore, no part of the electrical system was designed to meet IEEE-279-1971 and/or seismic Categcry I criteria.
The " dual setpoint" LTO protection systen is not a system that they are proposing be added to their pl ant, but rather it is an existing system wnich was implenented 2-163 016
during original plant start-up.
Since their jroposed modification to the existing CMS requires no additional equi pnent, they believe that major system modifications are unnecessary to meet the IEEE-279-1971 criteria for the following reason:
The proposed modification of the " auto-isolation" feature of the RHR-SV isolation valves will. es ul t in a mechanict'ly redundant relief capability by providing an alternate means (via the RHR SV's actuated at 400 psig) through which excess RCS pressure can bc relieved.
The pressuri:er 50RV's depend only on electrical power to operate; they are not air-operated valves.
The solenoids act.' ate a pilot which allows fluid pressure to open the valves.
Thus, a loss of station or instrunent air pressure will have no effect on the e erability of these s
valves.
The RHR SV's, on the other hand, are spring-loaded valves, and the RHR-SV isolation valves are motor-operated.
In the event of an electrical failure, the RHR-SV isolation valves will " fail o' pen," and the RHR SY' will still function.
We conclude that the 015 would not be susceptible to a common mode failure involving loss of offsite electrical power and air supply.
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t 2.4 AI. ARM SYSTEMS DESIGNS AND OPERATION Specific details concerning acceptable alarm systens design and operation for the OMS are des: ibed below.
2.4.1 Hich-Pressure Alar-n The NRC staff position requires that a high-pressure audio / visual alarm shall be used during low RCS temperature operations as an effective means to provide unambiguous infomation to the operator that a pressure transient is in progress.
A description of the MYAPCO high-pressure alam system design is as follows:
(1)
A canputer high-pressure alam is available ai, a pres-surizer pressure setpoint of 375 psig.
This alarm derives its pressure signal from a. differential pres-surizer pressure transnitter than is used to provide the low pressure setpoint feature for the pr(ssurizer S(RV 's.
The alann is always present in the computer when the pressure is greater than 375 psig; however, an operator keyboard procedure removes this alam from the canputer printout routines during nomal plant operation.
Therefore, operator action to reinstate this alarm in the computer printout routines is pro-vided in plant operating nrocedures where needed to ensure the presence of the alam.
(2)
The canputer alann actuates an annunciator on the main control board.
It requires operator acknowledgment and prints out the alam message on the canputer alarm typewriter.
This alam obviously depends upon the plant canputer being operable, and there are times during cold shutdown plant conditions when the can-puter must be removed fran service.
(3)
Another high-pressure alam is associated wi th the actuation of the pressurizer SCR V 's.
At 500 psig increasing, the pressurizer SCRV's receive an actu-ation signal to open.
The same signal actuates an annunciator on the main controi board anc alerts the operator that the pressurt:er SCRV's have actuated.
1165 018 2-10
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(4)
The RHR SV's are needed to mitigate overpressurization in the event of a pressurizer SCRV OMS failure, but the RHR SV's do not appear to be instrinented for a main control board alam.
Also, in the event of a pressurizer 50RV OMS failure, it is conceivable that the pressurizer SORY actuation alam would not func-tion to alert the plant operator that a pressure transient is in progress.
We conclude that this design is
. adequate to annunciate all overpressure transient conditions and does satisfy all of the NRC staff position.
2.4.2 Pressurizer-50RV Isolation and RHR-SV-Isolation Valve Alarms
- The NRC staff position requires that (1)
The upstream isolation valves to both the pressuri:er SORV's and the RHR SV's shall be wired into the over-pressure protection alarm in such a way that the alam will not clear unless the system is enabled and the isolation valves are open. Means shall be provided to ensure proper alignent ef the isolation valves during GiS operation.
(2)
The e!ams shall be of the audio / visual type and provide unambiguous information to tim operator.
A description of the MYAPCO isolation valve alam systen design is as follows:
(1)
An alarm will be provided to alert the operator to align the CMS on pl an t cooldown.
!30t h the pressurizer-SORY and RHR-SV i solatio i valves are inct uded in this alam.
- 1t snoulo ce noted that the enable alarm (Section 2.4.3) and the isolation valve alam (Section 2.4.2) are the same alam.
1163 019 2-11
(2)
Since the OMS is to be activated at reactor coolant 0
tenperatures below 220 F, tne proposed alann will annunciate at 225,F decreasing if either pressurizer-SCRV upstream isolation valve is closed.or if either RHR-SV inlet isolation valve is closed.
We conclude that this design satisfies the NRC staff position.
2.4.3 gable Alarm
- The NRC staff position requires thtt (1)
An aiann shall be activatad as part of the plant cooldown process to ensure the pressurizer 50RV " low pressure" setpoint is activated before the RCS tem-g perature is equal to or less than 220 F.
Prior to g
cooling the RCS below 220 F, operating procedures will require the activation of the CMS by setting the keylock permissive switch to the " low pressure" set-point and by setting the RHR-S V isolation and pressurizer-50RV isolation valve switches to the "open" position.
(2)
The alarm shall be of the audio / visual type and pro-vide unambiguous infonnation to the operator.
A description of the MYAFC0 enable. alarm system design is as follows:
(1)
An alarm will be provided to alert the opdrator to align the LTO system on plant cocidown.
(2)
Since the LTO system is to be activated at reactor g
ccolant temperatures bejow 220 F, the proposed alar n will annunciate at 225 F decreasing if the keylock pemissive switch is positioned to "HPSR" (only the nonnal, high pressure setpoint is activated).
- Lt snouic ce noted that the enable alann (Section 2.4.3) and the isolation valve alarm (Section 2.4.2) are the same alann.
1163 020 2-12
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We conclude that this design satisfies the NRC staff position.
2.4.4 Disable Alarm The NRC staff position requires that (1)
An al am shall be activated as part of the plant heatup process to ensure that the 50RV's are reset to the "high" getpoint when the RCS temperature is great-er than 300 F.
(2)
The alarm shall be of the audio / visual type and pro-vide unambiguous infonnation to the operator.
A description of the MYAPCO disable alam system design is as (1)
An alarm will be provided to alert the operator to align the components of the 015 for power operation.
(2)
This alarm will ann..iciate at a temperature of 300 F 0
increasing to warn the operator that the relief selector switch should be set to the "high" setpoint position and/or that ~~1e RHR-SV isolation valves are open.
We conclude that this design satisfies the NRC staff position if it can be shown that the alann is of the audio / visual t'ype.
2.4.5 Pressurizer-50R'l Ooen and RHR-SV Ocen Alarms The NRC staff position requires that (1)
An alam be activated to alert the operator that a pressurizer SCRV is in the "open" position.
(2)
An alarm be activated to aled the operator that either of the RHR SV's are in the open position.
116~4 021 2-13
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All alarms shall be of tle audio / visual type and pro-vide unambiguous infomation to the operator.
A description of the MYAPCO pressurizer-50RV open alarm system design is as follows:
(1)
A high-pressure alam is associated with the actuation of the pressurizer SCRV's.
At 500 psig increasing, the pressurizer 50RV's receive an actuation signal to open -
(2)
The same signal ae.tuates an annunciator on the main control board alarting the operator that the pres-suri:er SORV's have been ac'.:
ted.
This alarm is also used to ale. t the operator taat a pressure trans-ient is in progress.
We conclude that this desian satisfies the NRC staff position for the pressuri:er-50RV open alam.
- 2. 5 PRESSURE TRANSIENT REPORTING AND REC 010ING REQUIREMENTS The NRC staff position is that a pressure transient which causes the OMS to function, therecy indicating the occurrence of a serious pres-sure transient, is a 30-day reportable event.
In addition, pressare-recording and temperature-recording instrunentation are required to provide a pemanent record of the pressure transient.
The response time of the pressure / temperature recorders shall be compatible with press'ure transients
~
that increase at a rate of approximately 100 psig per second.
The Maine Yankee nuclear power plant does not possess provisions for continuously recording temcerature and pressure at low temperatures (including cold shutdown).
The plant does, however, utilize the process canputer which provt' des a canputer alam at 375 psig increasing.
The computer alam activates an annunciator on the main control board.
It requires acerat:r a:know'edgment and crints out the 31am message or the computer al arm typewriter.()3 02 2-14 = .,m-w -- e
- 2. 6 DISABLING OF ESSENTIAL COMPONENTS NOT REQUIRED DURING COLD SHUTDOWN The NRC staff position requires the deenergizing of safety injec-tion system (SIS) punps and the closure of. safety injection (SI) header /
discharge valves during cold shutdown operations. MYAPCO states that the disabling of essential canpanents during cold shutdown is as follows: (1) The " pull-to-lock" position associated with the con-trol switches for the charging punps deenergizes the i charging punp and inhibits all the automatic start signals and the SIAS from starting the punp. (2) The Maine Yankee Technical Specifications require one HPSI (charging) punp to be operable along with all associated valves and controls set for autcytatic initiation, whenever the RCS is greater than 210 F and 400 psig. Below these conditions, a charging punp is still required if a reactor coolant punp is operating in crder to supply the reac or coolant punp,with seal injection water. The nonoperating charging pump control switch is placed in the " pull-to-lock" positon to remove the pung from service, but it still retains its capability to ba started from the main control board should the operating puno becane unavailable. The HPSI header isolation valves are nornally closed, but must renain egergized until the plant conditions are less than 210 F and 400 psig. Below these con-ditions, the breakers for the valve motor coerators will be opened, tagged, and placed under administra-tive control. We conclude that thi s impl ementation satisfies the NRC staff position. 2-is 1163 023
3. TECHNICAL SPECIFICATIONS The Technical Specifications infonnation detailed in this section was derived from the RSB/00R SER entitled, " Safety Evaluation Report of the Overpressure Mitigating System for Maine Yankce Atomic Power Plant", dated November 1978. To ensure operation of the CMS, Hitz: has requird the Licensee to subnit Technical Specifications consistent with the analysi s provided. MYAPC0 has submitted tentative Technici.1 Specifications (refer to Reference 9 in the Appendix), and w find these to be acceptable with the following exception: The Licensee must add a statement to ensure that a reactor coolant punp may be started (or jogged) only if there is a steam bubble in the pressurizer with a utaximum level of 80 percent, or the steam generatorf ~ 0 RCS tenperature difference is less than 100 F. The tenative technical specificaticns for Maine Yankee are as follows: Technical Specification 43.4 (add s.te following) O. Low Tenperature Over;ressurization Protection
- 1. a. The power operated relief valves, aligned for the low pressure tetpoint, and the RHR spring relief valves shall be operable for RCS over;:ressure protection wnenever the RCS is less than the minimun pressurization temperature and the RCS is not vented.
b. If the conditions of 0.1.a are not met, the RCS shall be depressuri:ed and vented within eight hours. EXCE?T!ON: One power operated relief or RER spring ralief may be inoperacle for seven days. 1163 024 3-1
I 2. No more than one gPSI pmp may be energized at RCS tem-perature below 200 F. EXCEPTION: A second HPSI pmp may be energized fci-up to 5 minutes for the purpose of rotating operating equipnent. Technical Specification #4.1 - Tabla 4.1.3 (add the following) Channel Descriction Surveillance Function Frecuency Surveillance Method
- 10. Pressurizer a) Calibrate R
Apply blown pressure Power Operated to ti.e pressure sen v. ~ Reliefs - Low b) Test R(5) Mar.ua, actuation of ' Pressure Set-each POR to verify point solenoid aperation. (5) Must be perfomed prior to cooldown below 220 F. ~ We concur with the Reactor Safety Branch acceptance of these tenative technical specifications. 1163 025 e 3-2 -- : L -
4. CONCLUSIONS The eiertrical, instrunent6 tion, and control design aspects o! the low temperature overpressure mitigating system (OMS) for Maine Yankee were evaluated using those design criteria originally prescribed by the NRC staff and later expanded during subsequent discussions with the Licensee. th conclude that the MYAPCO Maine Yankee CMS design as described does satisfy all of the NRC criteria, recuirements, or staff positions. 1165 026 e 0 e
o APPENDIX 1163 027 O e e e A-1 e Memp e ~--an-em< -we -e - m w a,e-.-m=ye.
REFERENCES o 1. " Staff Discussion of Fifteen Technical !ssues Listed in Attachnent G November 3, 1976 Memorandum from Di rector, NRR to NRR S:aff",
- k. 'EG-0138, November 1976.
2. NRC Letter (Reid) to MYAPCO dated August 11, 1976. 3. MYAPC3 Letter (Naudenburgh) to NRC dated December 2,1976. 4. NRC Letter (Reid) to MYAPCO (Groce) dated January 28, 1977. 5. MYAPCO Letter (Johnson) to NRC dated March 25, 1977. ~ 6. PRC Letter (Reid) to MYAPCO (Groce) dated August 22, 1977. - 7. MYAPCO Letter (Johnson) to NRC dated October 24, 1977. 8. NRC Letter (Reid) to MYAPCO (Groce) dated January 10, 1978. 9. MYAPCO Letter (Johnson) to NRC dated Fwruary 24, 1978.
- 10. NRC Memorandum (Check to Reid), " Review of Maine Yankee Overpressure Mitigating System (TACS #6741)," December 18, 1978.
- 11. " Combined He atup, Cooldown and Pressure-Temperature Limitations,"
Maine Yankee Appendix G Infomation, Section 3.4 of Anend.ent No. 31, June 19,1977. 1163 028 A-2 m mW ' wme. W=4'Ow mo}}