ML20198J849
| ML20198J849 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 05/29/1986 |
| From: | Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | Noonan V Office of Nuclear Reactor Regulation |
| References | |
| SBN-1075, NUDOCS 8606030230 | |
| Download: ML20198J849 (14) | |
Text
_
SEABROOK STATION Enginaring Office May 29, 1986 Put2c Service of New Hampshire SBN-1075 T.F.
B7.1.2 United States Nuclear Regulatory Commission Washington, DC 20555 Attention:
Mr. Vincent S. Noonan, Project Director PWR Project Directorate No. 5
References:
(a) Construction Permits CPPR-135 and CPPR-136, Docket No. 50-443 and 50-444 (b) PSNH Letter (SBN-848), dated July 25, 1985,
" Response to SER Confirmatory Issue 40; Inadvertent Boron Dilution (15.4.6) - Final Response", J. DeVincentis to G. W. Knighton Subj ect :
Response to SER Confirmatory Issue 40; Inadvertent Boron Dilution
Dear Sir:
As a result of discussions with the Staff on May 22, 1986, changes have been made in our Inadvertent Boron Dilution Event analysis. These changes will require a revision to the FSAR and the proposed Seabrook Station Technical Specifications.
Attached for your use and information are the affected pages of FSAR Section 15.4.6 marked to reflect the necessary changes. The appropriate Technical Specification changes will be formally submitted to the Staff along with other comments being generated during the current Proof and Review phase of the Seabrook Station Technical Specifications.
The proposed Technical Specification change will prohibit the use of more than one reactor makeup water pump in Modes 4, 5, and 6.
We trust this information is acceptable and request the resolution of the subject confirmatory issue be reflected in the upcoming supplement to Seabrook's SER.
Very truly yours, E
John DeVincentis Director of Engineering Attachment cc: Atomic Safety and Licensing Board Service List 90I IlI Seabrook Station Construction Field Office P.O. Box 700 + Seabrook. NH O3874
Diane Curran Esquire Calvin A. Canney Harmon & Weiss City Manager 2001 S. Street, N.W.
City Hall Suite 430 126 Daniel Street Washington, D.C.
20009 Portsmouth, NH 03801 Sherwin E. Turk, Esq.
Stephen E. Merrill, Esquire Office of the Executive Legal Director Attorney General U.S. Nuclear Regulatory Commission George Dana Bisbee, Esquire Tenth Floor Assistant Attorney General Washington, DC 20555 Office of the Attorney General 25 Capitol Street Robert A. Backus, Esquire Concord, NH 03301-6397 116 Lowell Street P.O. Box 516 Mr. J. P. Nadeau Manchester, NH 03105 Selectmen's Office 10 Central Road Philip Ahrens, Esquire Rye, NH 03870 Assistant Attorney General Department of The Attorney General Mr. Angie Machicos Statehouse Station #6 Chairman of the Board of Selectmen Augusta, ME 04333 Town of Newbury Newbury, MA 01950 Mrs. Sandra Cavutis Chairman, Board of Selectmen Mr. William S. Lord RFD 1 - Box 1154 Board of Selectmen Kennsington, NH 03827 Town Hall - Friend Street Amesbury, MA 01913-Carol S. Sneider, Esquire Assistant Attorney General Senator Gordon J. Humphety Department of the Attorney General 1 Pillsbury Street One Ashburton Place, 19th Floor Concord, NH 03301 Boston, MA 02108 (ATTN: Herb Boynton)
Senator Gordon J. Humphrey H. Joseph Flynn, Esquire U.S. Senate Office of General Counsel Washington, DC 20510 Federal Emergency Management Agency (ATTN: Tom Burack) 500 C Street, SW Washington, DC 20472 Richard A. Hampe, Esq.
Hampe and McNicholas Paul McEachern Esquire 35 Pleasant Street Matthew T. Brock, Esquire Concord, NH 03301 Shaines & McEachern 25 Maplewood Avenue Donald E. Chick P.O. Box 360 Town Manager Portsmouth, NH 03801 Town of Exeter 10 Front Street Gary W. Kolmes, Esq.
Exeter, NH 03833 Holmes & Ells 47 Winnacunnet Road Brentwood Board of Selectmen Hampton, NH 03841 RFD Dalton Road Brentwood, NH 03833 Mr. Ed Thomas FEMA Region I Peter J. Mathews, Mayor 442 John W. McCormack PO & Courthouse City Hall Boston, MA 02109 Newburyport, MA 01950 Stanley W. Knowles, Chairman Board of Selectmen P.O. Box 710 North Hampton, NH 03862
SBN-1075 j
i I
1 i
a ATTACHNENT FSAR Channes to Support a Revision to the Seabrook Boron Dilution Analysis
]
SB 1 & 2 Amendment 56 FSAR November 1985 i
15.4.5 A Malfunction or Failure of the Flow Controller in a BWR Loop That Results in an Increased Reactor Coolant Flow Rate Not applicable to Seabrook.
15.4.6 Chemical and Volume control System Malfunction That Results in a Decrease in the Boron Concentration in The Reactor Coolant 15.4.6.1 Identification of Causes and Accident Description l
Reactivity can be added to the core by feeding makeup water into the reactor i
coolant system (RCS) via the reactor makeup portion of the chemical and volume control system (CVCS). A boric acid blend system is provided to permit the operator to match the boron concentration of reactor makeup water during normal charging to that in the RCS. The boric acid from the boric acid tank is blended with primary grade water in the blender and the composition is determined by the preset flow rates of boric acid,and primary grade water on the control board. The CVCS is designed to limit, even under various postulated failure modes, the potential rate of dilution to a value which, after indication through alarms and instrumentation, provides the operator sufficient time to correct the situation in a safe and orderly manner.
The opening of the reactor makeup water (RMW) control valve and one of the stop valves provides a flow path to the RCS, which can dilute the reactor
(
coolant. Inadvertent dilution from this source can be readily terminated by closing the control valve. The rate of addition of unborated makeup water to the RCS when it is not at pressure is limited by the capacity of the RMW pumps. Normally, only one RMW pump is operating while the other is on standby.
In order for makeup water to be added to the RCS at pressure, at least one charging pump must be running in addition to a RMW pump. With the RCS at pressure, the maximum delivery rate is limited by the capacity of the charging pumps, which is more limiting than the capacity of the RMW pumps.
Information on the status of the RMW is continuously available to the operator.
Lights are provided on the control board to indicate the operating condition
-of the pumps in the CVCS. Alarms are actuated to warn the operator if boric acid or demineralized water flow rates deviate from preset values as a result of system malfunction.
An additional source of unborated water which can dilute the reactor coolant is the boron thermal regeneration system (BTRS). Borated RCS water is depleted of boron as it passes through the BTRS.
The combined dilution capability from the RMW System and the BTRS potentially represents the worst possible case for RCS boron dilution. However, the BTRS is excluded as a potential source of unborated water during refueling, cold shutdown, and hot shutdown. Technical Specifications require that this be redundantly accomplished by rendering the BTRS chiller compressor inoperable and bypassing the BTRS regenerative demineralizers.T Thus, the limiting dilution riow rate during these three modes of operation is assumed to be the maximum
(
flow capacity of RMW epaten.
P4MP 64-d F a v % r m o, +,,hn,, d,,,g,,,f,.._4,o n s15.I
- 7"*'
E 1*'
f#7 2
gc 9 e ~;h k % c wk en opera %.
SB 1 & 2 Amendment 56 FSAR November 1985
(
O From this e tion, it seen at the por ~ n of the CS avat ble m'
ing the inc ing dll affec the time 1 se)shu wn ma
'n.
10 show at mix res ts of LOFT eriment L on bo n dilution I
hoccurs
'n volumes ha 'ng suffict tly hi fluid velo ' ties. T t is, T
locitie at be high ough to e e flo
- duced di
- sion, n
hFluid elocities ' various R components ere ca ulated for he limit r
onditio on one R ump operatt with the S syst full. Ta e 15.4-1 I
p vides a parison the calcul d velocitt versu elocities requ' ed for w-induced *ffusion ta from Ref nce 10.
The LOFT
-6 exper ne scalin was based n a reactor hich is ne ly ident* al to
- brook, o, the f
- d velocit s shown in ble 15.4-1 are app able.
The alcula steady-te veloc es are gre er than the require o
( induc boron d usion.
reover, t steady flo through the CS loops f
sure t they e swept o and, the fore, parti pate in th ixing p
ass.
conclus n, credi for mixin
'n the RCS ops is appr iate To cover all phases of plant operation, boron dilution during refueling, cold and hot shutdown, hot standby, startup and power operation are considered in this analysis.
a.
Dilution During Refueling
/'
The following conditions are assumed for an uncontrolled boron
\\.
dilution during refueling:
1.
Technical Specifications require that a minimum of 2000 ppe be maintained during refueling. With a 50 ppe allowance for uncertainties, the initial boron concentration is assumed to be 1950 ppe.
2.
The maximum boron concentration to lose all shutdown margin is conservatively assumed to be 1286 ppm. This bounds the condition of All Rods Out (ARO), Beginning-of-Life (BOL), no xenon, and cold (T O 700F).
150
- 3. g ilution flow i assumed to be the maximum capacity of-ehe-
-awe-RMW pump)(
gpe) with 0 ppe water returning to the i
RCS. Technical pecifications require the BTRs to be incapacitated for this mode.
4.
Mixing of the reactor coolant is accomplished by the j
~
operation of at least one residual heat removal pump.
3 ASS" 3
5.
A minimum water volume (6,996 ft ) in the reactor coolant system is used. This is the minimum volume of the RCS for 5<.
! (
f 15.4-23
--. -.-.~
SB 1 & 2 Amendment 56 FSAR November 1985 residual heat removal system operation. The water in the reactor vessel is assumed to be drained such that the nozzles are half-filled.
._.........__....;i::: :f the r :::::
l._.
2-t: th; h;1 Illico ov.
1m.,
th: h;; :nd celd S "
- I 8Ig vs.ac" 5
le;r h:15-r*11:, :r' th; ::::
r---
- i 3 ke*-
- th: :tr--
- )("
gm...;:rr- - ' : ret:r : :12 t 7_;,:.
Thi i; th;
.el----
- uir-4 fer ="" ;7cr;;ier., h; 2;;;.... lusiodm
- h; ;;1x::
- 5 the """? ite
6.
The density of RCS fluid is assumed to be 62.3 lb/ft3 (cold).
b.
Dilution During Cold Shutdown (With Filled Loops) 1.
The maximum boron concentration required to lose all shutdown margin is conservatively assumed to be 805 ppm.
This bounds the condition of All Rods In (ARI) less the highest worth assembly, BOL, no xenon, and cold (T T.700F).
2.
Technical Specifications require a minimum shutdown margin.
The minimum boron concentration required to meet this shutdown margin is conservatively assumed to be 880 ppm.
3.
Dilution flow is assumed to be identical to the refueling case, i.e.,ikk& gpm.
iso
(
4.
Mixing of the reactor coolant is accomplished by the operation of one residual heat removal pump.
5450 5.
A minimum water volume of 10,l'7 ft3 in the reactor coolant system is used.
8-8 e t e t ci:h;_: :h; ;rrrr-r*::: ::fb;-;;lin:.
It der: :: in;l oc ex- - ' - :f th: "-- r7:tr=. c e tt i-t '-- fr-herr 2
nici ; i: th: "00 1:;7;.
6.
The density of RCS fluid is assumed to be 62.3 lb/ft3 (cold).
c.
Dilution During Cold Shutdown (With Drained Loops) 1.
Technical Specifications require that 2000 ppe be maintained in this condition. With a 50 ppm allowance for uncertainties, the initial boron concentration is assumed to be 1950 ppm.-
2.
The maximum boron concentration requirod to lose all shutdown margin is identical to the case with filled loops, i.e.,
805 ppm.
3.
The assumed dilution flow rate is identical to the case with filled loops, i.e., 409 gpm.
M
(
15.4-24 I
1
-~ - - -
SB 1 & 2 Amendment 56 FSAR November 1985 4.
Mixing of the reactor coolant is accomplished by operation of l
at least one residual heat removal pump.
3(.55 5.
A minimum water volume of 4y9Mr f t3 in the reactor coolant l
system is used. This is the minimum volume of the RCS for residual heat removal system operation as described under I
Dilution During Refueling.
6.
The density of RCS fluid is assumed to be 62.3 lb/ft3 (cold).
d.
Dilution During Hot Shutdown 1.
The RCS coolant is assumed to be 500F subcooled (minimum) at a temperature of 3500F (maximum) so that a coolant density of 55.6 lb/ft3 is used.
1 2.
The maximum boron concentration required to lose all shutdown margin is conservatively assumed to be 747 ppm. This bounds the condition of 3500F, zero power, ARI less the highest worth rod, BOL, and no xenon.
3.
Technical Specifications require a minimum shutdown margin.
The minimum boron concentration required to meet this shutdown margin is conservatively assumed to be 828 ppe.
4.
In this mode of operation, makeup to the RCS may be either from the residual heat removal (RHR) pumps or the charging pumps depending on RCS pressure. In either case, the flow rate of unborated water would be limited by the capacity of S34. INSe 4he. RMW pumpg, i.e., 499 gpm.
c-
~
iso e.
Dilution During Hot Standby and Startup For unplanned dilution events during these two operational modes, the operator may be alerted by any of several indications including a reactor trip or shutdown monitor alarm. For those scenarios in which the operator is alerted to the event by a reactor trip, the remaining time to lose all shutdown margin is bounded by the analysis of dilution during power operation in the next section.
For those cases where the operator is alerted to the event by alarms other than a reactor trip, the time to lose all shutdown margin is bounded by the case analyzed below. For this bounding case, the reactor is assumed to be initially suberitical with all rods in less'the highest worth rod and with the Technical Specifi-cation requirement for shutdown margin met using soluble boron.
1.
The maximum boron concentration required to lose all shutdown margin is conservatively assumed to be 704 ppm. This bounds the condition of hot, zero power, ARI less the highest worth rod, BOL, and no xenon.
S.
15.4-25
Insert "A" The total volume includes the reactor vessel up to the nozzle centerline, one hot leg half filled up to the RHR connection, two cold legs half filled up to the RHR connections, and the active volume of one RHR loop.
Insert "B" The total volume includes the reactor vessel, one hot leg up to the RRR connection, two cold legs up to the RHR connections, and the active volume of one RHR loop.
Insert "C" 3
5.
A minimum water volume of 5450 f t in the RCS is used. This is the minimum volume of the RCS for RHR operation as described under Dilution During Cold Shutdown (With Filled Loops).
4
SB 1 & 2 Amsndment 56 FSAR November 1985 2.
Technical Specifications require a minimum shutdown margin.
The minimum boron concentration required to meet this shutdown margin is conservatively assumed to be 786 ppm.
3.
Dilution flow is assumed to be limited to the capacity of two charging pumps (240 gpm) with the reactor coolant system at 2250 psia.
4.
A minimum water volume (10,147 ft3) in the reactor coolant system is used. This volume corresponds to the active volume of the reactor coolant system, minus the pressurizer and surge line volumes.
5.
Mixing of the reactor coolant is accomplished by operation of the reactor coolant pumps.
6.
The density of the RCS fluid is assumed to be 46.4 lb/ft3 (5570F and 2250 psia).
f.
Dilution During Power Operation 1.
The maximum boron concentration required to lose all shutdown margin is conservatively assumed to be 704 ppm. This bounds the condition of hot, zero power, ARI less the highest worth rod, BOL, and no xenon.
(
2.
The'ainimum initial boron concentration is obtained by assuming full power, no xenon and control rods at their insertion limit.
BOL conditions are assumed consistent with part 1 above. A conservative value for this condition is 786 ppa.
3.
With the unit at power and the reactor coolant system at pressure, the assumed dilution rate is identical to the case for hot standby and startup, i.e., 240 gpm.
3 4.
The reactor coolant system volume assumed (10,147 ft )
corresponds to the active volume of the reactor coolant system excluding the pressurizer and surge line.
5.
Mixing of the reactor coolant is accomplished by operation of the reactor coolant pumps.
3 6.
The density of the RCS fluid is assumed to be 44.1 lb/ft (588.50F and 2250 psia).
15.4.6.3 Results of Analysis a.
Dilution During Refueling For dilution during refueling, the minimum time required for the shutdown margin to be lost is J+ f minutes. The shutdown monitor
(
75.9 15.4-25a
SB 1 & 2 Amendment 56 FSAR November 1985 2.3(.9 system alarm or other alarms will actuate within idrr9 minutes.
l-This will allow more than a half hour for the operator to prevent a loss of all shutdown margin.
b.
Dilution During Cold Shutdown (With Filled Loops)
For dilution during cold shutdown with filled loops,g2.9.2
\\the minimum time required for the chutdown margin to be lost is 497S minutes.
l The shutdown monitor system alarm or other alarms will actuate within.3ef minutes. This will allow more than 15 minutes for the l
operator to prevent a loss of all shutdown margin.
B.A c.
Dilution During Cold Shutdown (With Drained Loops) kol.3 For dilution during cold shutdown with drained loops, the minimum time required for the shutdown margin to be lost is e r f minutes.
l The shutdown monitor system alarm or other alarms will actuate within.3Prtf minutes. This will allow more than 15 minuts for the l
operator lto prevent a loss of all shutdown margin.
W 91.G d.
Dilution During Hot Shutdown Fordilutionduringhotshutdown,Ttheminimumtimerequiredto lose all shutdown margin is.at:S' minutes. The shutdown monitor i
system alarm or other alarms will actuate within Avtf minutes. This willallowmorethan15minutesfortheoperatortolpreventaloss of all shutdown margin.
t 8.9 e.
Dilution During Hot Standby and Startup For dilution during hot standby and startup, the minimum time required to lose all shutdown margin is 25.7 minutes. For this bounding case, the shutdown monitor system alarm or.other alarms will actuate within inutes. This will allow more than 15 l
minutes for the operato to prevent a loss of all shutdown margin.
9.1 f.
Dilution During Power Operation 1.
With the reactor in automatic control, the power and temperature increase from boron dilution results in insertion of the RCCAs and a decrease in the shutdown margin. The rod insertion limit alarms (low and low-low settings) provide the operator with a minimum of 24.4 minutes to determine the cause of dilution, isolate the primary grade water source, and initiate reboration before the total shutdown margin is lost due to dilution.
2.
With the reactor in manual control, and no operator action, there will be a power and temperature increase. Depending on initial control rod position, either rod insertion limit alarms
\\
15.4-25b
SB 1 & 2 Amendment 56 FSAR November 1985 4.
Barry, R. F. and Altomare, S., "The TURTLE 24.0 Diffusion Depletion Code," WCAP-7213-P-A, February, 1975 (Proprietary) and WCAP-7758-A, (Non-Proprietary) February, 1975.
5.
Barry, R. F., " LEOPARD, a Spectrum Dependent Non-Spatial Depletion Code for the IBM-7094," WCAP-3269-26, September, 1963.
6.
Taxelius, T. C. (Ed), " Annual Report - Spert Project, October, 1968, September, 1969," Idaho Nuclear Corporation IN-1370, June, 1970.
7.
Liimataninen, R. C. and Testa, F.
J., " Studies in TREAT of Zircaloy-2-Clad, UO - Core Simulated Fuel Elements," ANL-7225, January - June 1966, p. 177, November, 1966.
8.
Risher, D. H., Jr., "An Evaluation of the Rod Ejection Accident in Westinghouse Pressurized Water Reactors Using Spatial Kinetics Methods,"
WCAP-7588, Revision I-A, January, 1975.
9.
Bishop, A. A., Sandberg, R. O. and Tong, L.
S., " Forced Convection Heat Transfer at High Pressure After the Critical Heat Flux," ASME 65-Ht-31, August, 1965.
10.
da J.
.a Ber
. T.,
'Quie Loo Rep t on Bokn D utt E erim t L6
-L
-5 (M
,1 2).
\\
54 56
%gb Morita, T., et al., " Dropped Rod Methodology for Negative Flux Rate Trip Plants," WCAP-10298-A, June 1983.
I k
15.4-41
SB 1 & 2 Amende:nt 56 FSAR hovember 1985 TABLE 15.4-1 (Sheet 2 of 4)
Accident Event Time (sec.)
2.
3 pcm/sec Initiation of uncontrolled 0
reactivity RCCA withdrawal insertion rate Over-temperature AT reactor 27.7 trip signal initiated Rods begin to fall into core 29.7 Minimum DNBR occurs 30.1 c.
Startup of an Inactive Initiation of pump startup 0.0 Reactor Coolant Loop Power reaches P-8 trip setpoint 10.2 Rods begin to drop 12.2 Minimum DNBR occurs 12.6 1
d.
CVCS Malfunctions that
{
Result in a Decrease in Boron Concentration in the Reactor Coolant 1.
Dilution during Dilution begins O
refueling 4557 Operator isolates source of M
dilution; minimum shutdown margin occurs 2.
Dilution during Dilution begins 0
cold shutdown (filled loops)
I6 Operator isolates source of dilution; minimum shutdown margin occurs 3.
Dilution during Dilution begins O
cold shutdown (drained loops)
I operator isolates source of
.H4T dilution; minimum shutdown
[
margin occurs
(
..-.,.,m.
.._,,_,,,,y
_,,_..,,w.,,4,m.,,__,.,
.t-
-,,,,,_y._-.,,.,
-.y.--,
SB 1 & 2 Amendment 56 FSAR Nove:aber 1985 TABLE 15.4-1 (Sheet 3 of 4)
Accident Event Time (sec.)
4.
Dilution during Dilution begins
'O hot shutdown 1503 Operator isolates source of
.1497 dilution; minimum shutdown margin occurs 5.
Dilution during hot Dilution begins O
standby and startup operator isolates source of 1543 dilution; minimum shutdown margin occurs 6.
Dilution during power operation (a) Automatic Dilution begins; rods are at 0
reactor control insertion limit Operator isolates source of 1467 dilution; minimum shutdown margin occurs (b) Manual reactor Dilution begins; rods are at 0
control insertion limit operator isolates source of 1467 dilution; minimum shutdown marrin occurs 56 e.
Rod Cluster Control Assembly Ejection 1.
Beginning-of-Life, Initiation or rod ejection 0.0 Full Power Power range high nautron flux 0.041 setp31nt reached Peak nuclear power occurs 0.130 Rods begin to fall into core 0.54 l
56 Peak fuel average temperature 2.29 k
Peak heat flux occurs 2.32 Peak clad temperature occurs 2.32
}
SB 1 & 2 Amendment 56 FSAR November 1985 TABLE 15.4-14 SEABROOK RCS COMPONENT FLUID VELOCITIES AND
\\
BORON MIXING CHARACTERISTICS, Veloc ty(3) Requ red for
\\
volume FluidVelocity(I)(3)\\
FullMixin)(2)
Hot Leg 3.7x
-2 1,
10-3 kteamGenerato 1.5x1 1.5x 0-3 T es Pus Suction 3.2x10-2 1.5x10-Cold g
4.1x10-2 1.5x10-3 Core 5.3x10-2 1.5x10-3
. NOTES I
() Fluid v ocities are 1culated ass ng all RCS ps are off, only one pump is o (3,000 g y),
d the RCS 1 e are full.
r(
(2) These are inimum cyclic elocitie6 req red to indue ufficient ron diffusio for comple.te xing in thes volumes.
(3) Ve ocities er in meters /se ad.
F Is m