ML20052F588
| ML20052F588 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak, Byron  |
| Issue date: | 05/07/1982 |
| From: | Clifford J Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20052F540 | List: |
| References | |
| REF-GTECI-A-09, REF-GTECI-CO, REF-GTECI-SY, RTR-NUREG-0460, RTR-NUREG-460, TASK-A-09, TASK-A-9, TASK-OR NUDOCS 8205130218 | |
| Download: ML20052F588 (8) | |
Text
,
e UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of
)
)
TEXASUTILITIESGENERATINGCOMPANY,)
)
50-446 (Comanche Peak Steam Electric (Application for Operating License)
Station, Units 1 and 2)
)
AFFIDAVIT OF JAMES W. CLIFFORD I, James W. Clifford, being duly sworn, do depose and state:
Q.1.
By whom are you employed, and describe the work you perform?
A.1.
I am employed by the U.S. Nuclear Regulatory Commission as an Operational Safety Engineer (Nuclear) in Section A of the Procedures and Test Review Branch, Division of Human Factors Sa fety.
I review and evaluate licensee and applicant programs for nuclear power plant operating and maintenance procedures.
A Statement of Professional Qualifications is attached and incorporated into this affidavit.
Q.2.
What is the nature of the responsibilities you have had regarding the Comanche Feak Electric Station ("CPSES")?
A.2.
I am the assigned reviewer for sections 13.5.2, " Station Operating and Maintenance Procedures," and 15.3.9, " Anticipated Transients Without Scram (ATWS), of the CPSES Safety Analysis Report.("SAR").
I provided my review summary in the corres-ponding sections of the CPSES Safety Evaluation Report ("SER").
020513021s e20507 PDR ADOCK 05000 0
Q.3.
What is the subject matter of your affidavit?
A.3.
I~will address Board Question, 3, which requests:
" Describe the status of Safety Issue TAP A-9 (ATWS)' as it relates to CPSES 1 and 2."
In particular, I will discuss the current status of Applicants' compliance with NUREG-0460, " Anticipated Transients Without Scram for Light Water Reactors".
Q.4.
Describe the Commission's requirements for dealing with Anticipated Transients Without Scram ("ATWS").
A.4.
As stated in the SER for CPSES, a number of plant transients can be affected by a failure of the scram system to function.
For a pressurized water reactor, the most important transients affected include loss of normal feedwater, loss of electrical load, inadvertent control rod withdrawal, and loss of normal electrical power.
In September 1973, the Staff issued WASH-1270, " Technical Report on Anticipated Transients Without Scram for Water-Cooled Power Reactors," establishing acceptance criteria for anticipated transients without scram.
In con-formance with the requirements of Appendix A to WASH-1270, Westinghouse submitted an evaluation of anticipated transients without scram in Topical Report WCAP-8330, " Westinghouse Anticipated Transients Without Trip Analysis."
A reevaluation of the potential risks from ATWS has been published in NUREG-0460, Volumes 1 through 4 In March 1980,
the Staff issued Volume 4 of NUREG-0460, and in September 1980, the Staff presented its recommendation on ATWS to the Commission. After deliberation, the Commission has initiated a rulemaking proceeding on the issue of ATWS. The Staff expects that any ATilS rule adopted by the Commission would include an implementation plan for all classes of plants. The
- Applicants would then be required to modify CPSES to conform with the ATWS criteria in accordance with the implementation schedule set forth in the rule as adopted by the Commission.
To further reduce the risk from ATWS events during the period before completing the plant modification determined to be necessary by the Commission, the Staff has required that certain additional steps be taken by present and potential operating licensees. Ther.e additional requirements are set forth in Volume 4 of NUREG-0460, and may be summarized as follows:
(1) Develop emergency procedures to train operators to recognize ATWS events, including consideration of scram indicators, rod position indicators, flux monitors, pressurizer level and pressure indicators, pressurizer relief valve and safety indicators, and any other alarms annunciated in the control room, with emphasis on alarms n6t processed through the electrical portion of the reactor scram system.
--4 (2) Train operators to take actions in the event of an ATWS, including consideration of manually scramming the reactor by using the manual scram button, prompt actuation of the auxiliary feedwater system to ensure delivery to the full capacity of this system, and initiation of turbine trip.
The operators should also be trained to initiate boration by actuating the high-pressure safety-injection system to bring the facility to a safe-shutdown condition, i
The Staff is responsible for determining if the NUREG-0460 procedural actions which are required by the Staff are included in plant procedures. The specific criteria for the staff's review were provided by an internal NRC memorandum from Frank Schroeder to Robert L. Tedesco and Voss Moore dated June 23, 1980, which clarifies the requirements of NUREG-0460. This memorandum is attached to this affidavit as Attachment 1, and I hereby adopt and incorporate it into my affidavit.
The operator will be aware of the existence and content of the ATWS emergency procedures from the initial and requali-fication training programs, required by 10 C.F.R. Section 55, Appendix A.
The operators' knowledge of the procedures is tested by the written and oral initial operator license exams as required by 10 C.F.R. Sections 55.21 and 55.24, and by the annual requalification exams required by 10 C.F.R. Section 55, Appendix A, 4.b.
Q.5.
What is the status of Applicants' compliance with the emergency procedures and operator training requirements of NUREG-0460?
A.5.
The Applicants have committed to develop emergency operating procedures which include ATWS, in accordance with generic guidelines being developed by Westinghouse Owners' Group.
A review of the Applicants' ATWS procedure for conformance to these procedural requirements will be conducted in conjunction with the review performed for TMI Item I.C.1.
A description of the review and a finding on the acceptability of the Comanche Peak Anticipated Transient Without Scram procedure will be included under TMI Item I.C.1 in a future supplement to the CPSES SER.
Q.6.
Does the current status of Applicants' compliance with the procedure and training requirements for ATWS as set forth in Volume 4 of NUREG-0460 present a serious safety issue precluding the issuance of an operating license for CPSES?
A.6.
No. Meeting the interim requirements for emergency procedures and operator trainina of NUREG-0460 will provide a greater margin of safety from ATWS and associated severe consequences.
CPSES will not be licensed until the Applicants comply with NUREG-0460.
6-i The above statements and opinions are true and correct to the best of my personal knowledge and belief.
& # L/
JAf!ESW.CL;;FmMD Subscribed and sworn to me j
this (7tf day of May, 1982.
/
h_// A4 -
JW le Notary PubTic My Comission expires: 7[/((6L k
1 k
k i
I 1
~
f i
r
PROFESSIONAL QUALIFICATIONS JAf1ES WILLIAM CLIFFORD fly name is James William Clifford.
I am employed as an Operational Safety Engineer (ftuclear) in the Procedures and Test Review Branch, Division of Human Factors Safety, U.S. Nuclear Regulatory Commission, Washington, D.C.
I have held this position since October 1980. The Procedures and Test Review Branch reviews and evaluates licenee programs for nuclear power plant operating and maintenance procedures.
I have been assigned to this branch since October 1980.
From July 1978 to October 1980 I was a Naval officer qualified the equivalent of a shift supervisor at the Naval nuclear power prototype at Windsor, Connecticut, where my responsibilities included supervision of plant operations, training of new personnel and ensuring the continued expertise of experienced personnel.
From March 1976 to July 1978 I was a Naval officer assigned to a nuclear powered ship, where my responsibilities included safe operation of the ship's nuclear power plant.
I earned a BS degree in Systems Engineering from the U.S. Naval Academy in 1974. During my Naval service and my employtent with the NRC, I have attended several courses, varying from I week to six months in duration on plant engineering and operations.
i i
i I
i
a,_
sw w
w e
t i
e e
ATTACHMENT ONE e
s
}
t i
e O
f I
e u v e t o ".t A t t s f.UCLEAR R L 7Ut t.T OM cO*.*. :.510f;
- v. 2 w... ton o c.nws e
I
%..s
..Aff i
4.
,.e g3JUtt2 sten MEMORANDUt4 FOR:
Robert L. Tedesco, Assistant Director for Licensing, Division of Operating Reactors Voss Moore, Acting Deputy Director, Division of Human Factors Safety FROM:
Frank Schroeder, Assistant Director for Generic Projects, Division of Safety Technology
SUBJECT:
ATWS REVIEW FOR i EAR TEPJ4 OLS In a uemorandum dated June 9, 1980, addressed to R.L. Tedesco, I corr:nitted DST to prepare written guidance to be used by DHFS/PTRB in i
reviewing and evaluating the applicant's proposed ATNS procedures.
The enclosed instructions provide the necessary guidance for this evaluation.
./
Schroeder%', Assistanu Director Q4 Franfor Generic Projects, Division of Safety Technology
Enclosure:
Instructions for Reviewing Interim Emergency Operating Procedures for ATWS cc:
D. Eisenhut T. i;ovak V. I' core f
J. Youngblood D. Zicr. ann /
A. Schwencer T. Speis K. Parczewski P. Check K. Kniel R. Mattson A. Thadani L. Kintner
.h l ; v' ] ;
IriSTRUCTION FOR REVIEWIfiG.5NTERif' El' emf MCY PROCEDURES FOR ATHS Purpose of Emeraency Operatina Procedures ATNS concerns will be resolved in the future by reouiring the plants to rake the appropriate modifications in order to reduce the probability of occurrence of ATWS events and/or to mitiaate their effects. The Commission will, by rulemakino or other means, determine the required modifications and the schedule for the implementation of such nodifications.
In the interim period, while final resolution of ATUS is before the Cormission, the plants will be required to provide certain precautions.
The decision for permittina the plant to operate is based on the staff's conviction that the present likelihood of severe consequences arising from an ATHS event is acceptably small and presently there is no undue risk to the public from ATHS. This conclusion is based on engineering judqment in view of:
(a) the estinated arrival rate at anticipated transients with potentially severe consequences in the event of scram failure; (b) the favorable coeratino experi2nce with current scram systems; and (c) the limited nurber of operating reactors.
However, as a prudent course, in order to further reduce the risk from ATWS events during the interim period before comoletina the olant modifications determined by the Commission to be necessary, the staff believes the following steps should be taken:
PPRs 1.
Energency procedures be developed to train operators to recognize an ATWS event, including consideration of scram indicators, rod cosition indicators, flux monitors, pressurizer level and pressure indicators, pressurizer relief valve and safety valve indicators, coolant average temperature, containment temperature and pressure indicators, steam aenerator level, pressure and flow indicators, and any other alarns annunciated in the control room with emphasis on alarms not crocessed throuah the electrical portion of the reactor scram system.
2.
Ocerators be trained to take actions in the event of an ATHS includino consideration of manually scrammina the reactor by using the ranual scram buttons, prompt actuation of.th6'iuxiliary feetvater' system to assure delivery of the full capacity of this system, and initiatfion of turbine trip.
The operator should also be trained to initiate boration by actuation of the high pressure safety injection system to brina the plant to a safe shutdown condition.
Early operator action as described above would provide significant protection for all ATWS events which occur (1) as a result of cormon rode failure'in the electrical portion of the scram systen and (2} those which occur due to a common rode failure in the scram breakers or the rod drive system for which excessive prinary pressures are prevented by actuation of turbine' trip.
i
e s
3 Fnclosure 2
0', Rs 1.
Develos emergency procedures to train operators to recognize an ATWS event, including consideration of scram indicators, rod posi-tion indicators, flux monitors, vessel level and pressure indicators, relief valve and isolation valve indicators, and containment temper-ature, pressure, and radiation indicators.
2.
Train operators to take actions in the event of an ATPS including consideration of imnediately manual scramming the reactor by usino the nanual scram buttons followed by changing rod scram agitches to the scram position, stripping the feeder breakers on the reactor protection system power distribution buses, openino the sc' ram discharce volume drain valve, pronpt actuation of the standby liquid control system, and prompt placerent of the RHR in the pool cooling mode to reduce the severity of the containnent conditions.
Early operator action as described above, in conjunction with a recirculation punp trip, would provide significant protection for some ATHS evnts, namely those which occur (1) as a result of common mode failure in the electrical portion of the scra:.' systen and some portions of the drive system, and
/
i (2) at low power levels where the existing standby liquid control system caoability is sufficient to limit the pool temperature rise to an acceptable level.
All the licensees and the applicants should be (if they have not been) reauested to develop the appropriate emergency procedures dealing with ATWS events and submit them for the staff's review, i:ature of Eceroency Oseratina Procedures The procedure should address the following four areas:
1.
Symptoms of ATHS available to the operator in the control room.
2.
Automatic Plant Actions during ATWS.
3.
Immediate Operator Actions.
4 Subsequent Operator Actions.
The synptons of ATNS as well es the automatic and operator actions will vary with the initiatina transients and the procedures should take it into consideration.
The transients which produce rost limiting ATWS consequences should be covered by the procedures. These transients are listed tocether with the scram signals cenerated by them:
e Enclosure 3
Transient Scram Sicnals PWR Loss of t'ormal Feedwater (LOFW)
Mismatch' of steam /feedwater Low S/G level Overtemoerature AI Hioh pressurizer pressure High pressurizer level S/G low-low level Low reactor coolant flow Loss of Offsite Power (LOOP)
Low reactor coolant flow Open RC pur.p breaker Overtemperature AT Overpower AT High pressurizer pressure High pressurizer level Stuck Open Relief Valve (50RV)
Overtemperature Zri Law pressurizer pressure Hioh pressurizer level BUR Isolation valves position Closure of MS3V's Hiah neutron flux -
High vessel pressure loss of Offsite Power (LOOP)
Stop valves position High neutron flux High vessel pressure Inadvertent Opening of High Containrent pressure S/R Valve (IORV)
High suppression pool ter.psriture Each of these transients when followed by a failure of the reactor to scram will produce the consequences which may cause serious datage. The operator should be able to recognize that an ATHS event has occurred from the syrotcT.s-available to him jn the control room and to take appr6priste and'ticelPJ i
action to mitigate its effects.
Enclosure 4
1.
Sycotoms.:
The symptons available to the operator in the control room should provide him infornation that a transient requiring reactor scram had occurred and that the scram action had failed. The operator should have a clear indication that one of the auto scram parameters exceeded its trip setpoint.
For example, during the loss of normal feedwater transient in a PUR the pressurizer pressure exceeded its high pressure setpoint or that a mismatch of steam and feedwater was achieved.
He should also have indications of the plant's trip status.
This may consist either of a direct indication of the control rod position (rod bottom lights in PWR's) or indications of core neutron flux. Lack of rapid drop in nuclear power would indicate initiation of an ATWS (e.a., less than 10% of initial power in 5 sec. as indicated by Ills readout in PWR's).
2.
AutomaticActj?ns The automatic actions are'the actions taken by the plant without the operator's intervention in:2diately af ter an ATHS has occurred.
It is important for the operator to recognize them and to assure that they would have mitigating effects on ATHS consequences. The type of autonatic actions will depend on a plant desion and the type of initiating transient.
In general, in SHR's the recircula-tion pumps would trip automatically unless this feature has not yet been implemented and would reduce core power to about 30 percent.
The safety-relief valves would also open if reactor pressure exceeds individual valve setpoints.
In PUR's the turbine may trip for certain types of transients.
Mowever, for other types manual turbine trip would be required (especially for N-designed plants). This should be specified in the procedures. The other automatic actions which may be plant and/or transient specific are:
auxiliary feed-water startup, generator breaker trip, automatic steam dump actuation, initiation of HPTT and steam generator feed water bvnass reaulator control.
The discussion of these automatic actions should 'also~ be included in the procedures.
3.
Immediate Ooerator Actions The immediate operator actions are to mitigate the effects of ATUS and to bring the plant to a stable condition at which point a normal shutdown operation can be initiated. The inmediate operator actions will depend on the type of initiating transient and on the automatic plant response to ATHS.
The actions taken,by the operator at this point can be very icportant and shnuld be based on a careful analysis of all the available indications. The operator should be able to recognize that an ATHS event took place. The procedure should clearly specify the indications available to the operator during this phase of operation.
If two sinultaneous action by two operators are required, it should be clearly stated in the procedures.
Also a tire l
Enclosure 5
frame for performing different operations should be specified (Enc'losure 2 is an example of our recent questions on a set of procedures submitted by a "WR applicant).
In ceneral the operator actions in this phase consist of:
1.
attempt to scram the reactor by manually inserting control rods..
2.
attempt to scram the reactor by other neans (e.o., injection of liquid poison).
3.
nitigate (simultaneously) the effect of the ATUS event.
The procedure should specify which of these actions should be.'erforned simultaneously.
In D:R's the operator should first assure that the recirculation nu os have tripoed by an autonatic plant action.
If they are not tripped the operator should proceed to trip them raanually. He should then attempt to scram the reactor manually by using different scramrrina netho('s.
Typically scramming the reactor should be attempted by: depressing scram buttons, placing the ode selector switch in shutdown position, de-energizina the power to the pilot scran valves by renoving the fuses, bleeding air from the scram valve
/
actuation lines by closing the instrument air supply valve to PCU scram
\\
valves, manually driving control rods into the core or de-energizing the individual hydraulic control unit scram pilot air valve solenoids.
Reactor scram by iniectino sodium centaborate solution into the reactnr by initiatina the standby lic0id control. system.-(SLCST sh6uld'be"attenoted.when. the4iicary scram techniques cannot secure fast reactor scram. At a rule, once started SLCS should never be shut off unless neutron power is down. The operator should also ensure that the hich pressure nake up systems are deliverina water to the reactor.
Sinultaneously, the operator should initiate the suppression pool cooling mode of the RHR system.
In PHR's (Westinghouse designed ones in particular), the nost important innediate cperator action is to trip the turbine manually if it is not already tripped by autonatic plant action and ensure that all auxiliary feedwater cumos are supplyino water to the steam generators. The operator should also simultaneously attempt to manually scram the reactor. This could be achieved either by trip-pina the breakers powering the control rod drive MG sets or by tripping the reactor trip breakers at the MG sets.
If this fails, an attempt should be nade to canually insert the control rods and at the sane tine start injecting boron into the primary coolant system. This should be followed by other actions ccnsisting mainly of deter:rining the status of reactor systems required for plant recovery from ATWS.
If performance of any of these systems is found to be defective, an appropriate action should be taken.
The procedure should be very specific about describing these corrective actions.
O Enclosure 6
4 Subseouent Operator Actions The subsequent operator actions are the actions taken after the reactor has recovered from the immediate consequences of an ATWS event, its power has been reduced to a safe level and the operator wants to start an orderly shutdown procedure.
Basically, the operator should assure that the primary and secondary systems are naintained at a steady tenperature and pressure condition and that all the systems needed for maintaining the plant at this condition are operating properly.
The operator should also assure that enough negative reactivity has been introduced into the core to assure a sufficient cold shutdown margin.
In verifying different plant systems the operator should refer to the appropriate plant operating procedures and take the corrective actions specified by thase procedures. The operator should eventually bring the plant to a cold shutdown condition, consistent with the plant's technical specification.
Evaluation of Emeroency Operatina procedures Using the guidelines presented in the previous section, the reviewer should evaluate the emergency operating procedures for conpleteness and should assure that they provide the operator with sufficient information to er.able hin to perform the operations which would minimize the ATWS consecuences deleterious to the plant.
Since these consequences may be plant specific, the emergency ATUS procedures should be preparad individually for each plant.
In reviewino these procedures their plant specific character should be taken into consideration and the reviewer should evaluate them relative to a particular plant design.
In many cases he may find that the proposed procedures may not be adequate to fully protect the plant during ATWS events occurring at full power and only partial reduction of ATWS consequences was possible.
However, these plants may be fully protected when operating at a reduced power (see Enclosure 3 for Sanple SER for Operation at Low Powers).
7 ENCLOSURE 2 SAMPLE OUESTIONS ON AN ATUS PROCEDURE A.
Sycotoms 1.
The procedure lists the parameters which cause the reactor to scram, but does not describe the actual indications available to the operators in the control room which would make him aware that an ATPS event has occurred.
These ATWS symptoms would depend on initiating event and, therefore, they ought to be evaluated for at least the followino three key events:
Loss of Main Feedwater loss of Offsite Power Stuck Open PORY In making the evaluation it is irportant to show for each event what symptoms would indicate to tha operator that scram action was called for but did not occur.
B.
Automatic Action 1.
This section does not address how the automatic actions relate to ATWS.
Some of the automatic actions (e.g., turbine trip) may not even occur after an ATWS. This should be specified in more detail in the procedure.
2.
Why is automatic actuation of HPSI not included in this section of the procedure?
C.
Immediate Operator Action 1.
The procedure should specify critical indications available to the operator consistent with the initiating event and assurption that the reactor, trip has not occurred.
2.
The immediate actions that the operators have to take after AT1.'S has occurred and an attempt to manually scram the reactor from the control room has failed should follow two parallel paths. Uhile ene operator l
should continue the operation of manually scramming the reactor by trip-ping the breakers powering the control rod drive MG sets, the other
~
8 operator should initiate the other actions heading to safe shutdown of the plant. The procedure should reflect that the actions described in sections A.2.b and A.2.c and those described in sections B.1 and B.2 are to be perforced simultaneously.
Section B should require sequential actuation of turbine trip, all auxiliary feedwater pumps, and hioh pressure safety injection system. (See Figure 1).
3.
Describe the actions taken by the operator when he discovers, during the verififation of reactor coolant system status (section C), that the conditions are not within the prescribed limits. What is the impact of loss of offsite power on availability of those signals to the operator.
What is the shutoff head of the HPSI pumps? What provisions are taken to prevent pump damage when HPSI is operating against ths RCS preisure which is higher than the shutoff head of the pump?
D.
Subsequent Ooerator Action 1.
What is the time frame for these actions?
/'
2.
What criteria are provided to verify that:
t The auxiliary feedwater system is providing the necessary flow to the
~
a.
steam generators, b.
The HPSI is providing necessary flow to RCS.
C.
The containment heat removal is beina accomplished, if the containrent conditions are outside the normally specified valves.
3.
h'1at additional procedure does the operator have to follow in order to bring the plant to and maintain in a cold shutdown condition after an ATWS? For example, what boron concentration should be maintained in the RCS?
n m
)
SUBSEQuf4T ACT10 tis hac& Action
' Initiated.
Failure to lancdiate Opera-verify RCS, steam Long Icra t
Transient Generator Contain-Shutdorn Scram tor Actions Symptoms Two Operators ment Paraneters Value",
e Symptoms t')
, 2 3
4 t
t ral time ncs Operator il Manual Scram If outside specified Describi special limits, describe the actions in bring
~
Attenets operator actions.
plant to 4 cold shutdmai condi-Openator #2 tion and main-tain tlut
' Assure that condition.
a)turbinetripped
'.b) all AFWS provid-Ing flow c)IIPSIp(roviding flow shut off head)
In that order.
Wiia t, i f a ny, i s
.the inpact of stuck open PORY.
figure 1.
Generalized Approach to be followed for writing ATWS procedure (s) b
10 EHCLOSURE 3 1
SAMPLE SER FOR LOW POWER LICENSE on Energency(Ooerating
'fe have reviewed the TVA submittal of January 10, 1930 ATWS) events.
Frecedures for the postulated anticipated transients without scram
'.le provided our comments on the proposed procedures and made recommendations for changes.
The proposed procedures must be modified in accordance with our contents and instructions to be acceptable for full power ooeration.
Fewever, the Sequoyah plant nay be operated at low power (less than or eoual to five percent of full cower) prior to conpletion of procedures modifications without undue risk to the health and safety of the public. Our conclusion that low power operation is acceptable is based on our understanding of the expected plant response to the relevant AT',45 events to occur under these operatino conditions.
Sanole of " Evaluation Findinos" (Full Fower License)
The reviewer should verify that the procedure contains sufficient infor. ation and his review supports the following kinds of statements and conclusions:
"The instructions orovided in the procedure for pernit the acerator to diagnose an ATWS event and take the appropriate actions reouired for minimizino its effects and brinoing the plant to a safe shutdown condition.
The instructions include the description of the automatic responses of the plant as well as the operator's actions taken innediately after he diagnoses ATHS and later when he attempts to bring the plant to a cold shutdown condition."
l l
l l