ML19296D324
| ML19296D324 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 02/27/1980 |
| From: | Woolever E DUQUESNE LIGHT CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19296D325 | List: |
| References | |
| TAC-49941, TAC-7170, NUDOCS 8003030494 | |
| Download: ML19296D324 (2) | |
Text
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(412) 456-6000 435 Sixth Avenue Pittsburgh, Pennsylvania 15219 February 27, 1980 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Attention:
A. Schwencer, Chief Operating Reactors Branch No. 1 Division of Operating Reactors Washington, D.C.
20555
Reference:
Beaver Valley Power Station, Unit No. 1 Docket No. 50-334 Revision to NPSH Modifications and Revised Technical Specifications Gentlemen:
Enclosed are three (3) signed originals and thirty-seven (37) copies of a revision to the two reports including revised Technical Specifications:
1.
" Analysis and System Modification for Recirculation Spray and Low Head Safety Injection Pumps NPSH" sub-mitted in November, 1977.
2.
" Additional System Modification for Recirculation Spray and Low Head Safety Injection Pumps NPSH" sub-mitted in September, 1979.
The purpose of this revision to the referenced reports is to increase the sodium hydrcxide concentration in the chemical addition tank and to add chemical injection pumps to the quench spray system.
These changes address concerns by NRC staff members concerning final containment sump pH and verification of the analysis method used to decermine the performance of the chemical addition system.
Very truly yours,
-1rf E.
J. Woolever Vice President Engineering & Construction enclosures 8008080 4/
\\
i
Wn (CORPORATE SEAL)
Attest:
Qdx H. W. Staas Secretary COMMONWEALTH OF PENNSYLVANIA)
)
SS:
COUNTY OF ALLEGHENY
)
On this
.2 7
- day of
/ b R h M ^' [
- 1980, before me, Em7AT.n w cunmmr a Notary Public in and for said Commonwealth and County,"p"ersonally appeared E. J. Woolever, who being duly sworn, deposed, and said that (1) he is Vice President of Duquesne Light, (2) he is duly authorized to execute and file the foregoing Submittal on behalf of said Company, and (3) the statements set forth in the Submittal are true and correct to the best of his knowledge, information and belief.
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DONALD W. SHANNON, NOTARY PUBLIC PlTTSSURGH, ALLECHENY COUNTY MY COMMISSION EXPIRES JUNE 7,1983 Member, Pennsylvania Associaten cf Notanes
SYSTEM MODIFICATION FOR CHEMIC AL ADDITION QUENCH SPRAY SYSTEM O
JANUARY 1980 BEAVER VALLEY F0WER STATION - UNIT NO. 1 DOCKET NO. 50-334 FACILITY OPERATING LICENSE NO. DPR-66 800308 0 ' c
SECTION 1 INTRODUCTION This report supplements correspondence and two previous reports:
1.
" Analysis and System Modification for Recirculation Spray and Low Head Injection Pumps Net Positive Suction Head" dated November 17,1977 (hereafter referred to as "The 1977 report").
2.
" Additional System Modification for Recirculation Spray and Lou Head Safety Injection Pumps Net Positive Suction Head" dated September 1979 (hereafter referred to as "The 1979 report").
The 1977 report described modifications required to ensure that the recirculation spray (RS) and low head safety injection (LHSI) pumps will be operable following a loss-of-coolant accident (LOCA). These include diversion of Quench Spray (QS) water to the recirculation spray (RS) pump suctions, larger diameter QS pump impellers, reduction of QS flow once cubatmospheric conditions are achieved, modifications to the Refueling Water Storage Tank (RWST) to increase available RWST water, installing cavitating venturis to throttle LHSI flow, and installing eductors for caustic delivery.
The 1979 report indicated that a modification to the present gravity feed system would provide acceptable chemical addition capabilities thereby eliminating the need for installing eductors. Additionally, the 1979 report indicated that some Recirculation Spray and Quench Spray nozzles would be replaced by a different type in order to ensure that the assumption of 90 percent spray effectiveness remained valid for all modes of operation.
This report documents changes in the approach for chemical addition to the quench spray system summarized above. These changes address concerns expressed by NRC staff members concerning final sump pH and verification of the analysis method used to determine the performance of the chemical addition subsystem. The NaOH concentration in the Chemical Addition Tank (CAT) will be increased, and chemical injection pumps will be added to the QS system.
1-1
SECTION 2 SYSTEM DESCRIPTION AND MODIFICATIONS 2.1 System Description and Description cf Previously Proposed Modifications Modifications proposed in the 1977 and 1979 reports are illustrated in Figure 1.
The details of the rationale behind the modifications are discussed in those reports.
After review of the 1979 report, the NRC staff expressed concerns regarding predictability of NaOH injection and the attainment of a satisfactory final sump pH.
NRC staff members indicated during a November 1979 meeting, that full-scale testing would be necessary to confirm predicted performance of the system with respect to NaOH injecticn. It was indicated that scale model testing would probably not be an acceptable confirmation of hydraulic transients. Since radiological and other considerations render full-scale testing impractical on an operating plant, positive displacement chemical injection pumps will be added to the quench spray (QS) system to ensure proper NaOH injection (see Figure 2).
A second concern expressed by the NRC staff involved predicted final containment sump pH. The 1979 report predicted a worst case sump pH of 7.2.
NRC staff concerns centered on reevolution of iodine. In order to ensure a final, worst case sump pH of no less than 8.0 as stated in the Final Safety Analysis Report (FSAR), the concentration of NaOH in the chemical addition tank (CAT) will be increased (see Section 3).
2.2 Additional Modifications to the Chemical Addition System The existing gravity feed system will be replaced by a redundant positive displacement pumped (PDP) injection system. The PDP injec-tion system is shown in Figure 2.
This modification will be designed censidering minimum and maximum chemistry limits, tank levels, and single failures of pumps and valves.
Four rotary positive displacement pumps and electric motor drivers will be provided to meter the NaOH into the QS pump suctions. These pumps will conform to the latest applicable American Society of Mechanical Engineers (ASME) code for Class 3 equipment, as well as other industrial standards as applicable. Each PDP is designed to deliver 32 gpm of NaOH to the QS pump suction line. This modificatica vill require one motor-operated isolation valve per chemical addition train. Manual isolation valves, piping, and flew instrumentation to allow reliable operation and in-service testing vill also be provide 1.
2-1
2.3 Electrical Considerations The addi'. ion of two chemicalinjection pumps (5 hp each) on each diesel generator will have a negligible effect on the operation of the diesel generators, since the small pumps are included in the same sequence with the much larger quench spray and outside recirculation spray pump motors. The effect upon voltage and starting current is insignificant.
The chemical injection pump motors shall comply with IEEE 323-1974.
2.4 Control Systems Upin actuation of the quench spray systems by a Containment Isolation Pht;e B (CIB) signal, the quench spray pumps are started, and the block valves located between the quench spray chemical injection pumps and the quench spray pump suction line are opened. The quench spray chemical injection pumps are then started automatically.
One quench spray chemical injection pump per train will stop upon closure of the cutback control valve.
Pumps will stop upon low flow from the associated QS pump, lov level in the CAT, or a motor electrical protection trip.
The motor-operated valves at the discharge of the QS chemical injection pumps auto =atically close upon lov level in the chemical addition tank (CAT).
22
OUENCH SPRAY RING A
n n CHEMICAL ADDITION TANK (CAT.)
RECIRCULATING V
V v
[
SPRAY RING MOV REFUELING WATER LOOP SEAL
/
PIPING ADDITION
/
(EXISTING)
STORAGE TANK (RWST)
[ --- -- 7 l- - - --lo-f
)
d FLOW TRANSMITTER RECIRCULATING k
T (EXISTING)
+
ORIFICE I
- '8 SPR AY RING (NEW)
V1 a
h ORIFICE TEST LINE r-NM X
S I
l
/j g TO RWST ORIFICE 14'(NEW) 41
/
F Z
H 5
T
~~
n
< 8
.MOv 3
1
<r (EXISTING) 3E l
r- - - I O
I E
ORIFICE k
/
(NEW)
O l
b f
ORIFICE j'
eMOV V
\\ /
(NEW) l (EXISTING)
+ TO TR AIN *B' gE CTOR MOV CONTAINMENT l
l Moy (EXISTING) l (EXISTING)
MOV D
(NEW)
OUTSIDE INSIDE OUENCH R.S. PUMP R.S. PUMP SPRAY PUMP (EXISTING)
(EXISTING)
(NEW IMPELLER)
REVISIONS:
LEGEND:
F(GURE I 11/17/77 - REVISION O
- NEW ELECTROHYDRAULIC RS E. QS SYSTEM MODIFICATIONS VALVE OPER ATORS 9/ 4/79 -REVISION I BE AVER VALLEY - UNIT 1
- -- N EW DUQUESNE LIGHT CO.
g
,, s * '
QUENCH SPRAY RING
^^^
CHEMICAL ADDITION TAN K (CAT.)
R ECIR CUL AT ING SPRAY RING V
V V
[
LOOP SE AL MOV REFUELING WATER PIPING ADDITION k
(EXISTING)
STORAGE TANK p - - - - - -]
(RWST)
_ _po - -
q
-g-- J L - - - -Ho-y l
FLOW TRANSMITTER g
ORIFICE I
RECIRCULATING T (EXISTING)
+
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'l
(~ _ q SPRAY RING (NEW)
T g
.i.
0 $
I h
f TEST LINE
> TO TR AIN'S' r-p h
E I
/ f-TO RWST 5 e(RIFICENE W)
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/ Z T
l O
y g
s{T l 8
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,__ _ _ __.L _ _ _ _)
l l
dL CHEM.
INJECTION l l
l z
r 7 l
F g
l I
N 3
fu"E,"3 OO OO 5
l k
l o
oc g
l l
l
\\}[
ORIFICE
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h /
(NEW) b------
4 MOV
.g c z,m,z REACTOR
- - - - - -D4- -
MOV CONTAINMENT l
l May (EXISTING)
(EXISTING)
MOV D
(NEW)
OUTSIDE INSIDE QUENCH R.S. PUMP R.S. PUMP SPRAY PUMP (EXISTING)
(EXISTING)
(NEW IMPELLER)
REVISIONS LEGEND:
FIGURE 2 is/17/77 - REVISION O
--NEw RS & QS SYSTEM MODIFICATIONS 9/ 4/79 - REVISION I BE AVER VALLEY-UNIT l I/ 2/80 -REVISION 2 DUQUESNE LIGHT CO.
SECTION 3 SYSTEM ANALYSIS 3.1 Description of Changes to Chemical Addition Subsystem In order to assure uniform spray chemistry under all postulated operating modes of the quench spray and safety injection systems, the chemical injection subsystem of the quench spray system will utilize positive displacement chemical addition pumps for delivery of sodium hydroxide additive to the suction of the quench spray pumps as shown in Figure 2.
Two equal size pumps in parallel are utilized to deliver the caustic upon initiation of the quench spray system by a Containment pressure signal. The chemical injection pumps are interlocked with quench spray flow, RWST level, and CAT level to control the chemical additive subsystem operation.
3.2 System Operation Since both trains of the quench spray system are identical, and since the two trains do not interact with one another during opera-tion, it is only necessary to discuss the operation of one train.
Upon initiation of each train, a quench spray pump is started, the chemical addition valve is opened, and the two chemical injection pumps are started. When the RWST level drops to the level where the quench spray flow is cut back, one chemical injection pump is tripped thus maintaining nearly the same chemistry as before cutback.
When either the quench spray pump discharge flow is low or the CAT is exhausted, the remaining chemical injection pump is tripped and the CAT is isolated.
3.3 System Evaluation The objectives of the chemical addition subsystem changes are:
1.
To maintain a spray pH between 8.5 and 11.0 (in compliance with Standard Revieu Plan Section 6.5.2).
2.
To obtain a sump pH of at least 8.0 after all caustic has been added under the most limiting mode of system operation.
The quench spray pH is maintained between 8.5 and 10.9 while caustic addition is occurring. Under those conditions where both trains of the chemical addition subsystem are available to the quench spray system, the CAT may be exhausted before the RWST and the quench spray will become a boric acid spray for the duration of quench spray operation.
The sump pH will have reached a minimum of 8.5 in these cases and thus the recirculation spray pH will be at or above 8.5.
This also occurs when one diesel generator fails, thus failing one safety injection train and one quench spray train.
3-1
The minimum ultimate sump pH of 8.0 is attained with the failure of one chemical addition valve. Under this condition full draudown of the RWST is coupled with minimum drawdown of the CAT. This results in the minimum amount of caustic addition to the sump. All pH cal-culations conservatively consider minimum and maximum tank levels and boric acid and sodium hydroxide concentrations.
The sump pH transient for the most limiting condition discussed above is shown in Figure 3 3-2
ti.0
~
SAFETY INJECTION TR AI N FAILURE p H :9.6 9.0 p H : 8.9 CHEMICAL ADDITION VALVE FAILURE 8.o
[
p H = 8.0 7.0 Ia 6.0 5.0 4.0 3.0 I
I e
I i
i i
I o
1000 2000 3000 4000 5000 TIME (SEC.)
SUMP pH VS TIME IN EXTREME ACCIDENT CASE FIGURE 3 LIMITING SUMP pH TRANSIENTS BEAVER VALLEY-UNIT I DUQUESNE LIGHT COMPANY J AN U ARY 1980
SECTION 4 SAFETY EVALUATION A safety evaluation of the chemical addition modifications and replacement of the spray nozzles has been performed.
This safety evaluation supplements the safety evaluation included in the 1977 and 1979 reports.
The modifications addressed in this report are being made in conjunction with previously reviewed modifications to the recirculation spray and low head cafety injection syste=s.
These modifications ensure that system performance is consistent with the basis established in the FSAR.
4.1 FSAR Chemical addition is a feature of the quench spray subrystem of the contain-ment depressurization system. The design basis, system description, and system evaluation were presented in Section 6.4 of the FCAR and, the effec-tiveness of the spray system for iodine removal is evaluated in Section 14.3.5 of the FSAR.
The modifications do not alter the design basis or system evaluation pre-cented in the FSAR.
Changes in the system description are presented in Sectiin 2 of this report.
4.2 Technical Specifications The limiting conditions of operation, surveillance requirements, and bares for the technical specifications related to the containment deprescurization eystem and its interfaces were reviewed and proposed changes are precented in Appendix A of this report.
Changes to the chemical addition system technical specifications will increace the concentration of NaOH uced, but they do not alter the basis for the existing technical specifications.
These changes introduce additional cur-veillance requirements to the technical specifications but no chancec to the existing specification basis.
4.3 Unreviewed Safety Question The additional system modifications described in this report do not create an "unreviewed safety question" as defined in 10CFR50.59.
The modifications are being made in conjunction with the analysis previously submitted for the RS and LHSI systems.
The modifications do not:
4-1
Increase the probability of occurrence or the consequences of an a.
accident or malfunction of equipment important to safety previously evaluated in the safety analysis report.
As stated in the 1977 and 1979 reports,the modification does not change plant parateters which would adversely affect a LOCA analysis.
The modifications do not adversely affect the iodine removal capability, containment depressurization, the capability to remain depressurized, or the calculated offsite dose.
Thus, the original safety analysis performed in accordance with 10CFRIOO remains valid.
b.
Create a possibility for an accident or malfunction of a different type than any evaluated previously in the safety analysis report.
The modifications represent refinements in the final system design as opposed to major system revisions.
As such, the modifications ensure system operation and performance within the conditions of the license, c.
Reduce the margin of safety as defined in the basis for any technical specification.
4.4 Safety Implications The additional nodifications described in this report do not affect normal power operation of the station or automatic operation of +Se systems.
The changes are final system design refinements which ensure system operation consistent with the licensing commitments.
4-2
APPENDIX A Pii0 POSED TECHNICAL SPECIFICATION CHANGES The following pages are enclosed:
3/4 6-15 3/4 6-16 A-1 8003030
-o0-
CONTAINMENT SYSTEMS CHEMICAL ADDITION SYSTEM LIMITING CONDITION FOR OPERATION 3.6.2.2 The chemical addition System shall be OPERABLE withs a.
A. chemical addition tank containing a volume of at least 4,700 gallons of between 19.5 and 20 percent by weight NaOH solution, and b.
Four chemical injecticn pumps each capable of adding NaOH solution from the chemical additive tank to a containment spray system pump flow.
APPLICABILITY:
MODES 1, 2, 3, and 4.
ACTION:
With the chemical addition system inoperable, restore the system to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />; restore the chemical addition system to OPERABLE status within the next 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or be in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
SURVEILLANCE REQUIREMEIUS 4.6.2.2 The chemical addition system shall be demonstrated OPERABIE:
At least once per 31 days by verifying that each valve (manual, a.
power-operated, or automatic) in the flow path that is not locked, sealed, or otherwise secured in position, is in its correct position.
b.
At least once per 31 days on a STAGGERED TEST BASIS by:
1.
Starting each injection pump 2.
Verifying that each injection pump operates for at least 15 minutes.
3 Cycling each testable power-operated or automatic valve in the flow path through at least one complete cycle of full travel.
4.
Verify that on recirculation, each injection pump develop a flow between 31 and 34 gpm.
3/4 6-15
CONTAIM E?C SYSTD!S SURVEILLANCE REQUIRCENTS (Cont'd) c.
At least once per 6 months by:
1.
Verifying the contained solution volume in the tank, and 2.
Verifying the concentration of the NaOH solution by chemical analysis.
d.
At least once per 18 uonths, during shutdevn, by:
1.
Cycling each valve in the chemical addition system flow path, that is not testable during plant operation, through at least one co=plete cycle of full travel.
2.
Verifying that each automatic valve in the flow path actuates to its correct position on a test signal.
3/4 6-16