ML18139B861
| ML18139B861 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/23/1982 |
| From: | Leasburg R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Harold Denton, Varga S Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.1, TASK-TM 118, NUDOCS 8205030192 | |
| Download: ML18139B861 (17) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY
. RICHMOND~ VIRGINIA 23261 R.H.LEASBUBO VICE PH.ESIDENT NUCLEAR OPERATIONS April 23, 1982 Mr. Harold R. Denton Office of Nuclear Reactor Regulation u.s. Nuclear Regulatory Commission Washington, D.C.
20555 Attention:
Mr. Steven A. Varga, Chief Gentlemen:
Operating Reactors Branch No. 1 Division of Licensing Serial No.
PSE&CS/DPB:
Docket Nos, 118 jdm 50-280 50-281 License Nos. DPR-32 DPR-37
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REQUEST FOR ADDITIONAL INFORMATION
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-'\\'2 REACTOR COOLANT SYSTEM VENTS ( ITEM II. B.1) 1 :"J
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SURRY POWER STATION UNITS 1 AND 2
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The attached responses concerning the Reactor Coolant Syst:~<v'~1f~~;i0f)~Y are provided in reply to your request for additional information datecr--'
February 22, 1982.
Please advise if further information is required.
Very truly yours,
/)tS)L~~
~ R. H. Leasburg Attachment cc: Mr. James P. O'Reilly, Regional Administrator Office of Inspection & Enforcement Region II 101 Marietta Street, Suite 3100 Atlanta*, Georgia 30303 Mr. R. C, DeYoung, Director Office of Inspection & Enforcement Division of Reactor Operations Inspection Washington, D,C.
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- 1.
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REQUEST FOR ADDITIONAL INFORMATION FOR SURRY 1 & 2
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- 1.
Sub:nit operating guidelines for reactor operator use of the reactor vessel head and pressurizer venting system including the f~llowing:
- a.
Guidelines to determine when the operator should and shoul~ not manually initiate venting, and inf~rmation *and instrumentation required for this determination (reference NUREG-0737 Item 11.B.l Clarification A. (2)).
The guidelines to determine whether or not to vent should cover a variety of reactor coolant system conditions (e.g., pressures and temperatures).
The effect of the containment hydrogen concentration on the decision to vent or to continue venting should also be addressed considering the balance between ~he need for increa~ed core cooling and decreased containment integrity due to elevated hydrogen levels.
- b.
Methods for determining the size and location of a noncondensible ga*s bubble (reference Position (2) and Clarification A. (2)).
- c.
- Guidelines for operator use of the vents, including information and instrumentation available to the operator for initiating or terminating vent usage (reference Position (2)).
- d.
Required operator actions in the event of inadvertent opening, or failure to close after openi.ng, of the vents including a description of the provisions and instrumentation necessary to detect and correct these fault c*onditions (reference.Position (2) and Clarification A.(2)).
- e.
Methods which in lieu of venting will assure that sufficient. liquid or steam will flow through the steam generator U-tube region so that decay heat can be effectively removed from the reactor coolant system (reference Clarificat~on c.(2)).
Response: a.
It is our intention to operate the RCS Head Vent System in accordance with the recently developed~ Function Restoration Guideline, FR-I.3, A copy of this generic guideline is provided for reference as Attachment I.
Engineering basis for the guideline is included in a generic background document also supplied by~*
- 1.
The guideline background document lists, in addition to RVLiS, four symptoms which should cause the operator to suspect the presence of voids in the RCS.
The conditions are covered as part of Operator Training.
- 2.
The guideline checks RCS stability, attempts to collapse the void, checks pressurizer conditions, and RCS.
subcooling prior*to vent operations,
- 3.
Instrumentation required for plant response is presently available with the exception of RVLIS.
A temporary alternative m~thod for detecting an~ sizing voids has been provided
- in the ba*ckground document.
See Attachment IL
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Hydrogen indication and control equipment are available at present.
Step 11 of the guideline addresses contai~~ent H2 concentration and cqlculation of vent time based on the conservative assumption o~ the void consisting of 10 0% Hydrogen.*
Tennination due to Hydrogen concentration is addressed in Step 12.
- b.
RVLIS is required to absolutely detennine if the void is in the reactor head.
The methods described in Attachment II are valid for determination of void existance and size, but do not discriminate as to location.
At present the use of the pressurizer vent is not addressed in generic guidelines.
- c.
Guidelines for vent initiation are provided in Steps 1 thru 11 of FR-I. 3.
Termination criteria are reviewed in Step 1'2 prior to venting.
In Step 13 venting is stopped when RVLIS indicates a full or stable level or when any of the criteria of Step 12 are reached.
Instrumentation, with exception of RVLIS, is presently available and operable.
- d.
The generic guideline does not address inadvertant opening of vent valves as such.
In Step 13 the operator is instructed to maintain redundant valves closed while not being operated.
This would preclude a single failure from opening a flow path.
The capability of local manual isolation is provided.
Should the above methods fail, it is anticipated that the event would. be detected and handled as a small break LOCA in accordance with existing plant procedures.
Present instrumentation is appropriate for this condition, e,l, The caution prior to Step 1 of the guideline attempts to maintain void stability by leaving RCPs in their present condition, Tripping RCPs.could result in gases collecting in S/G U-tubes, while starting a *RcP would disperse gases collected in the head or pressurizer and make removal difficult,.
- 2. An attempt is made to collapse steam voids ~rior to any venting operation.
- 3. Pressurizer level is monitored and maintained throughout the operation.
SI is initiated if level cannot be maintained.
- 4. RCS subcooling_is maintained greater than S0°F.
- 6. If during venting any RCPs stop, the venting is to continue.
- This minimizes the amount of gas which will collect in S/G U-tubes while natural circulation establishes itself.
2, Demonstrate that the reactor vessel*head and pressurizer venting system flow restriction orifices are smaller than the size cor~esponding to the definition of a loss-of-coolant accident (10 CFR Part 50, Appendi~ A) by providing the pertinent design p3.rameters of the reac*tor coolant makeup system and a calcula_tion of the maximum_ rate of* 1oss of reactor coolant through the vent orifices (reference NUREG-0737 Item 11.B.l Clarification A, ( 4) )
- Response: The orifices on the vent system are 3/8 inch I.D.
Per the Westinghouse system design basis the mass flow through a 3/8 inch break is within the capacity of the normal makeup water system.
3, The following items apply to the portions of the reactor vessel head and pressurizer venting system that form a part of the reactor coolant pressure boundary, up to and including the second normally closed valve (reference NUREG-0737 Item 11,B,l Clarification A,(7)):
- a.
Verify that the piping, valves, components, and supports designated QA Category 1 on your drawings are classified Seismic Category 1 and Safety Class 2 (Safety Class 1 where the size corresponds to the 10 CFR Part 50 Appendix A definition of a loss-of-coolant accident),
b, Provide the design temperature and pressure of the piping, valves, and components.
- c.
Describe the existing methods and instrumentation that has ~een provided to detect and measure reactor vessel head and pressurizer vent isolation valve seat leakage (reference Appendix A to 10 CFR Part 50, General Design Criter.ion 30),
- d.
Describe the materials of construction and verify that they are compatible with the reactor coolant chemistry and will be fabricated and tested in accordance with SRP Section 5.2.3, "Reactor Coolant Pressure Boundary Materials,"
Response: a,
- b.
C, The piping, valves, and supports design_ated QA Category 1 are classified Seismic Category 1 and Safety Class 1 or 2 where appropriate.
The design conditions of the piping and vaives are 650°F, 2485 psig, Leakage is detected by an increase in the amount of makeup required to maintain a normal l~vel in the pressurizer, Leakage inside the containment is drained to the containment sump where it i_s monitored, Leakage is also detected by measuring the a:irborne activity of.the containment atmosphere and monitoring the containment pressure.
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. d.
The piping and valve material in contact with reactor coolant water is austenitic stainless steel.
The material in contact with the reactor coolant is compatible with the attached chemistry.
A.
Reactor Coolant Water Electrical Conductivity Solution pH Oxygen Chloride Fluoride Hydrogen Suspended Solids pH Control Agent (Li70H)
Boric Acid Silica Aluminum
-Calcium Magnesium
.( 0 to* 40 uMhos/cm at 25°c 4.2 to 10.5 at 250c
<.. 0. 005 J?Pm
.C::. 0.15 *ppm
(. 0.15 ppm 25 to 50 cc(STP) Kg H20
~ LO ppm 0.7 to 2.2 ppm Li 0 to 4000 ppm B
< 0.2 ppm
<.
- 0, 05 ppm
.( 0,05 ppm
< 0.05 ppm B.
Reactor Coolant Makeup Water Cation Conductivity
.(.
1 uMhos/cm at 25°c Solution pH 6.0 to 8.0 at 25°c Oxygen
< 0,10 ppm Chloride - Fluoride
< 0.10 ppm Total Solids
< LO ppm Suspended Solids
.( 0.10 ppm Silica
< 0.10 ppm Potassium
(;: 0,01 ppm Sodium
<. 0.01 ppm Aluminum-
<: 0.02 ppm Calcium**
< 0.02 ppm Magnesium
< 0.02 ppm 4,
Verify that the following reactor vessel head and pressurizer venting system failures have been analyzed and found not to affect the essential operation of safety-related systems required for safe reactor s_hutdown or mitigation of the consequences of a design basis accident:
- a.
Seismic failure of venting system components that are not designed to withstand the safe shutdown earthquake,
- b.
Postulated missiles generated by failure of venting system components,
- c.
Fluid sprays from venting system component *failures.
Sprays from normally unpressurized portions of th~ vents that are Seismic Category 1 and Safety Class 1, 2 or 3 and have instrumentation for detection of leakage from upstream isolation valves need not be considered,
- e**
Response: a.
All components and.piping in the RCS *vent system have been designed to withstand a safe shutdown earthquake.
b,c. Per NRC Branch Technical Position MEB 3-1, it i?. not necessary to postulate breaks in piping of diameter one inch or less.
Therefore, jet impingement, pipe whip, or missile analysis is not required.
- s.
Verify that any nearby structures, systems, and co:nponents essential to safe shutdown of the reactor or mitigation of the consequences of a design basis accident ~re capable of withstanding the effects of the anticipated mixtures of steam, iiquid, and noncondensible gas discharging from the reactor.vessel head and pressu,rizer venting system,*.
Response: The spray from both the RCS and Pressurizer Vent Systems are directed into the refueling cavity such that they do not impinge on any components, The pressurizer vent system discharge is directed straight down into the refueling cavity.
T.~e RCS Vent System discharge is directed.at a 45° angle into the refueling canal from the reactor vessel head.
The attached sketch (Attachment III) details the approximate location o_f the vent system discharge for both units.
All components in* this area were originally designed or have.. been qualified to withstand the effect of a LOCA, therefore, *no additional analysis need be performed.
6, Verify that operability testing of the reactor vessel head and pressurizer, venting system valves will be performed in accordance with subsection IWV of Section XI of the ASME Code for Category B valves (reference NUREG-0737 Item 11,B.l Clarificatiori'A.(11)).
Response: Operability testing will be in accordance with subsection n.;rv of Section XI of the ASME Code for Category B valves, 7,
Verify that all displays (including alarms) and controls, added to the control room as a result of the TMI Action Plan requirement for reactor coolant system vents, have been or will be considered in the human factors analysis required by NUREG-0737 Item l.D.1, "Control-Room Design Reviews,"
Response: The controls and displays added to the control room by this modification will be considered in a human factors analysis to be conducted at a later date in accordance with NUREG-0737 Item l,D,l,
ATTACHMENT I
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FR-1.;3 RESPONSE TO' VOID IN REACTOR VESSEL
.:....,UC1'1 Ne. tD<:,,e Ba~ic 1 Sept. 1981 STE? --- ACTION/EXPECTED RESPONSE. i----1.
RESPONSE NOT OBTAINED
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Do not stop any running RCPs or s,tart any stopped RCPs until completion of this guideline.
1 2
~ecord RCS Pressu~ - ___ PSIG Verify SI Syrtem - HOT IH OPERATIOH
. 3 Check Stahle RCS Conditioru:
4 5
6
- a. Pressurizer level - STABLE BETWEEN 40% AND 60%
- b. RCS pressure - STABLE
Vessel:
- a. Tum on pressurizer heaters to*
increase pressure by 50 psi
- b. Maintain balanced charging and letdown flow
- c. Maintain pressurizer leve*I -
GREATER THAN 20 %
Verify Void Collapse In Reactor Vessel:
- a. Reactor vessel level -
- RlSlNG TO FULL
- b. Reactor vessel level -
FULL C. Return to procedures in effect lsokrte Letdown.
1 of 5
!E SI system is in operation, THEN go to step 9 *
- a. Manually cdiust letdown and charging. *
- b. Operate heaters and spray.
- c. Adiust steam dump.
- c. !f level less than 20 %, THEN tum off pressurizer he-ders AND
. return to step 3.
a..!f. level not rising, THEN go to step 6.
- b. lf. level not full, TrlEN go to step 6.
FR-1.3 STEP 7
8 9
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Bcn1c 111 Syn, F'f'C'dT\\ m H *:
RESPONSE TO VOID IN REACTOR VESSEL
. (Cont.)
ACTION/EXPECTED RESPONSE Ched: Pretsumer Condition::
- a. Pressurizer level - GREATER THAN 10%
- b. Pressurizer level - BffiVEEN 20% AND 90%
- c. RCS pres~ure - GREA TE~ _THAN... _
OR EQUAL TO PRESSURE RECORDED IN STEP 1 1 Se-pt. 1981 RES?ONSi: NOT OBTAINE~
- a. lncre-:ise charging flow..![ level
- cannot be maintained above 10 %
with _maximum charging, THEN monuo lly initiate SI and go to E-0, REACTOR TRIP OR SAFETY INJECTION, STEP 5.
- b. Adjust charging flow.
- c. Energize he<Jters. !£ pressure decre-Jsing
- in an uncontrolled manner, THEN manually initiate Sl 9nd go to E-0, REACTOR TRIP OR SAFm' INJECTION, STE? S.
~OTE Venting of the RPV may result in RCS pressure decreasing below SI initiation setpoint.
Check Low Pres.surizer Pressure SI Signal Status:
- a. Manually block.
- a. l.E less than~ °F, THEN increase steam dump. 1£~ °F subcooling can.not be obtained, THEN go to E-0, REACTOR TRIP OR SAFEiY INJECTION, STEP 5.
'l.
(/) Enter :rum of umperoturt and pr=u mcasurrmenc :.;-.rem errors rrar.slaud in10 rempuarurt using sa:urarion rabies, PLUS 50"F.
2 of S
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RPONSE TO VOID IN REACTORVESSEL STE?
. 10 (Cont.)
ACTION/EXPECTED RESPONSE Pn:part5 Contoinmerrt For Reactor Yes;el Venting:
- a. Isolate containment:
- 1) [Enter plant specific list]
- b. Start containment air circulation equipment:
l) [Enter plant specific list]
- c. Verify hydrogen control ~uipment available:
- 1) [Enter plant specific list]
11*
Determine Maximum Allowable Venting Period:
- a. Containment Hydrogen concentration - LESS THAN..!!L. %
- b. Calculate maximum venting 7:--""Lio1
---* (See graph on page 5) 1 Sept. 1981
- RESPONSE.NOT OBTAINED
- a. Reduce hydrogen concentration:
[Enter plant specific menns]
IF ANY vent tennination criterion in step 12 is reached or exceeded while venting, immediately stop venting.
12 Review RPV. Vent Termirnrtion Criteria With Control Room Personnel:
- Containment hydrogen concentration -
GREATER THAN 3 % BY VOLUME
- RCS subcooling - LESS THAN.£J_ ° F
- Pressurizer level - LESS THAN 20 %
- Venting period - GREATER _THAN PE:Z!OD CALCULATED IN STEP 11.
(l) E.-:ter plant specific value.
(::'.:) E:::tcr sum of t=pc:.uure and prosure mc.asurc.'TlcDt SY5tem errors t=l.tted inio tc:::ipcr..turc using s.arur2.ticio tab!~.
3 of 5
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FR-1.3 PONSE TO VOID IN REACTO (Cont.)
....,..........~*,.
Basic 1 Sept. 1981 STE? --- ACTION/EXPECT~D.RES?ONSE 13 14 Vent Re-actor Vessel
- a. Open valves in one vent path
- b. Close both volves when:
l) Reactor vessel level - FULL OR STABLE
-OR-
- 2) Any termination criterion of step 12 is reached c..!£ venting stopped because of ANY criteria in step 12, THEN return to,
step 7.
Chedc Presroriz.er Level - STABLE 15 Return To Guideline In Effect
-END-4 of 5 RE.s?ONSE NOT OBTAINED
- a. IF either of series valves in selected path foils to open, Tl-iEN dose both valves_ and open valves in second path.
Adjust iniection and letdown, as required.
- r* ----,---h-
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. ESPONSE TO VOID IN REACTOR VESSE~
Bcaic FR-1.3 (Cont.)
l Sept. 1981 In~
2000_ A Containment Volume (ST?)
~
( C V 1
~) X (Cont. Pressure)
-g ont.
o ume, 1-14 7
. ps1a t B Maximum H2 Volume to be Vented t
(3.0% Cont. H2 Concentrntion)X A
~
100%
X 492°R (Cont. Temperature)
)500 RCS PRESSURE (PSI) 100...,
I 500 T
0 -
l 1000 2 <
j <
I
(
VENTING PERIOD 2
T T
'T 2000 3000 4000 I
5000 8/C
(SCFM) 5 of 5 l
6000 I
e ATTACHM~T lI 4.0 ADDITIONAL J/'EORMATlON FOR PLANTS h'ITHOUT A REACTOR VESSEL* LE \\!cl.INSTRUMENTATION SYSTEM The infornoetion provided herein contains. a rrethod for detecting and sizing v~ids in the RCS.
No *discrimination between voids in the reactor vessel and voids in the steam generators can be made.
For plants without a*reactor vessel level system, this method can serve a critical safety m:initor function, as well as confirming the success of void re~oval operations.
If gases are present in the reactor coolant system, then the pressurizer pressure and level controls will not respond as they normally would.
The total gas volume can be estimated by performing a routine pressur-jzer control operation and then compar_ing the expected results with *the actual results.
This is the technique utilized in the following steps.
If the safety injection system is in service, then the following steps are *not applicable since normal pressurizer control will not be maintained." The recorrrnended steps, followed by a brief e_xplanation if needed, are given below.
- 1.
Achieve a constant pressurizer level and pressure condition, with normal controls being maintained.
- 2.
Place fhe RCS wide range or pressurizer pressure and the pressurizer level on trend recorders.. The scale should be 150 psig pressure and 1 0% of span for 1 eve 1.
System pressure and level are placed on trend recorders to achieve better accuracy for. recording their values.
The transient is not expected to exceed a 150 psi.or 10% of span change in RCS conditions.
FR-I. 3 83.16T:1 13
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- 3.
Record the following parameters.
RCS Pressure
=
PSI PZR Level
=
o'
/0*
Charging Rate
=
.GPM Sea 1 Injection Flow =
GPM Seal Leak off Lo,,.r
=
GPM Time
=
These recordings will become the initial para.rneters in the following calculation.
- 4.
Isolate the RCS letdown flow, turn off all pressurizer heaters, and terminate the pressurizer spray by placing the spray control in.
manual and zeroing the demand signal.
A condition is established where the pressurizer level will change only as a result of mass being injected into tAe RCS.
- 5.
Allow the RCS charging flow to either increase RCS pressure 100 psi or increase pressurizer level 5% of span~
- 6.
Record the RCS pressure, pressurizer level and time.
7
- RCS Pressure=
PSI PZR Level
=
Time
=
These recordings will become the final par~Tieters in the following calculation.
Reinitiate RCS letdown flow and restore normal pressurizer pressure and level control.
FR-I. 3 83161:l 14
-i
-- - - - ~
- 8.
Calculate the initial and final-pressurizer vapor space volumes.
Initial Vapor Volume = (1-PZR Level% X Total Cylindrical PZR"Vol. Fr* 3) +
(Upper Spherical Volume FT 3)
=
F.T 3 Final Vapor Volume
= (Initial Volume)+ (6 PZR Level X Total Cyl1norical Volume*)
=
FT3.
- Pressurizer volume less upper ana lower spherical dome volumes.
- 9. Determine the total charged volume into the RCS.
Chargea Volume= (Charging+ Seal Injection - Seal Leakoff GPM) X (Time) X (
lGAL) 7.4~
-FT.:S
=
FT3-
- 10. Determine the expecterj pressurizer level change.
Expected 6 level F. R-I. 3 8316T:l
- (Charging Volume FT3) X (
- lOO%
)
Total PZR Volume ~T3
=
15
h g::.:.:.
11.. If the actual pressuriz-er level. change is less than the exp£::cteo E.:.:-..:'.*
E=*
level change then a gaseous voio exists in th~ reactor coolant systeffi.
Perform the following step to oetermine th£:: volume of the RCS voia.
If the actual pressurizer level change is less than the expecteo change (or if no level change was witnessed) then gaseous voios exist in the reactor coolant system. This.is a result of the gaseous voids contracting when the pressure was intreasea b~ the charging ~low.
This will limit Dr prevent a normal pressurizer level increase. The void contraction may even be large ~nough to cause an actual decrease in the pressurizer level.
Step 12 should then be performed to estimate the total -volume of the gas voids in the RCS.
- 12. The initial and final RCS gaseoui void volumes can be calculateo from the following equations.
Initial RCS Voio = (Initial Vapor Volume7:.(Final Vapor Volume)-(Chargeo* Volume)
(l _ ln~t1al Pressure F ma 1 Pressure
=
FT3
. Final RCS Void = (Initial RCS Vo i o) X ( Initial
{Fina 1 Pressure)
Pressure)
=
FT~
The RCS voio volume contraction is equal to the change in pressurizer level converted to volume.
Also the ratio of final voio vol~me to initial voia ~olume is equal to the ratio of initial ~CS pressure to final RCS pressure. From these two equations the two unknowns (initial ano final RCS voio volume) *can be determineo by inserting one equation into another. The tnitial voio volume is calct.ilateo first ano then fit into the volume/press*ure ratio to aetermine-the final void volume.
- F R-1. 3
.8316T:l 16
. REFUELING CAVITY_
ATTACHMENT I II UlJ 1I2 REACTOR VENT RCS VENT SYSTEM DISCHARGE POINTS SURRY UNITS 1 AND 2 REFUELING CAVITY
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PRESSURIZER VENT