ML20116D428
| ML20116D428 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 07/24/1996 |
| From: | Jain S DUQUESNE LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-95-07, GL-95-7, TAC-M93429, TAC-M93430, NUDOCS 9608020142 | |
| Download: ML20116D428 (36) | |
Text
.
ver Valiey Power Station Shippingport. PA 15077-0004 l
l l
SUSHIL C.JAIN (412) 393-5512 DMalon Vice President Fax (412) 643-8069 Nuclear Services July 24,1996 Nuclear Power DMslon 1
U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 l
l
Subject:
Beaver Valley Power Station, Unit No. I and No. 2 BV-1 Docket No. 50-334, License No. DPR-66 l
BV-2 Docket No. 50-412, License No. NPF-73 Response to Request for Additional Information Regarding Response To Generic Letter 95-07 l
Reference:
1.
NRC Letter, " Request For Additional Information (RAI) Regarding l
Response To Generic Letter (GL) 95-07, " Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves,"
Beaver Valley Power Station, Unit Nos. I and 2 (BVPS-1 and l
BVPS-2) (TAC Nos. M93429 and M93430)," dated June 24,1996.
This letter provides the Duquesne Light Company (DLC) response to the NRC's RAI (R.eference 1). Please find the response in the Attachment to this letter.
If there are questions regarding this letter, please contact Roy K. Brosi, Manager, Nuclear Safety Department at (412) 393-5210.
l Sincerely, Sushil C. Jain Division Vice President Nuclear Services 020010 1
Attachment
200F), with no subsequent cooldown, then l
required to open?
l lYES l X lNO
]
OPS (e) is the hot valve (>200F) required to close while the system / valve is l
being cooled down and signaled to cpen before the valve cools down (i.e., not completely cooled down)?
l lYES l X lNO IF didIORielis *YES*, TM VALVE MAY BE SUSCEPTIBLE TO TWintAL BINDING, CONTIM./E WITH QUESTION 6fe).
5 System Screening / Evaluation Criteria for Wedge Effect Thermal Smding NED (a) is the actuator sized for unseating thrust which takes into account thermal binding of the wedge?
l lYES l X lNO ops (b) Does a procedure exist that requires cycling the valve at a cookng Delta T interval of approximately 20-50 degrees FF l
lYES l X lNO
.. - - - - - - - - - - - - - - - - - - - - - - - - - ! 't?R'*.! 6M.*E* ?2CER WH, quf[p_N_6fck Q T,WR,qs_E_GO_TO S T,EP 6.,
OPS (c) is the valve closed hot followed by a cooldown of >100 degrees l
and then required to open?
l lYES l X lNO ops (d) is the hot valve required to close while the system / valve is cooling down to > 100 degrees F (i.e., subject valve closure terminates l
cooling) and required to open after the valve has cooled down?
l lYES l X lNO 1125t9610:05 AM Rev.3 mwnuexs s
l GENERIC LETTER 95-07 SCREENING FORM l
142
.Vcive Mirk Ns.: MOV-SI-869A Gets style: FLEX WEDGE
==
Description:==
CH PUMP TO RCS HOT LEG ISOL Page 2 of 4 i
j 5 (cont'dl j
ops (e) Can a temperature gradient of > 100 degrees F develop across the l
j valve after it is closed and is the valve then required to be opened?
l lYES l X lNO JF 6iel,fdlOMie)IS *YES*, TM VALVE MAY M SUSCEPTlaLE TO TMnMAL alNOING, GO TO STEP 0.
1 l
8 Cornponent Level Criteria for Pressure Locking NED (a) 18 the valve a Solid wedge Gate valve?
l lYES l X lNO 4
f l
NED (b) Does the valve have a design feature that mitigates Pressure Locking f-(hole in the disk, bonnet bypass, bonnet relief, air trap, etc.)?
l lYES l X lNO I
NED If YES, What is it?
IF Gle}orfbi13 'YES*, IGNOM PMSSUM LOCKING, PROCESS IS COMPLETE.
7 System Screening / Evaluation Critoria for Hydraulic Pressure Locking j
NED/
(a) Has valve inservice testing (e.g. MOVATS Testing) during 9
MEAD operation closely duplicated the hydraulic pressure locking j
condition and been shown to operate successfully?
l X lYES ' l lNO 1
a i
NED (b) 18 the actuator sized for maximum exp4Cted bonnet pressure for li the hydraulic pressure locking condition?
l lYES l X lNO j
'Ulb.!!.".*R*r.fmgCffMH_ g,qSTfN_7fel QT,MQ1SEfffg Qf_S[lgN 8taj, j
ops (c) is the valve normally or occasionally exposed to high pressure j
fluid, and is the attached piping potentially depressurized prior to valve actuation?
l X lYES l lNO 1
1 1
ops (d) is the valve, which is normally exposed to low pressure fluid, potentially l
subjected to high pressure fluid due to back leakage from a high pressure source and is the attached piping potentially j
depressurized prior to valve actuation?
l lYES l X lNO l
4 l
IF 7(:W(d)IS *YES*, TM VALVE MAY M SUSCEPTICLE TO PMSSUM LOCKING, CONTINUE WITH QUESTION 8tel 8 System Screening / Evaluation Criteria for Thennally induced Pressure Locking 1
NED (al is the actuator sized for maximum expected bonnet pressure due to the thermal pressure locking condition (i.e., temperature in the bonnet)?
l lYES l X lNO i
OPS (b) Are temperature changes associated with this valve less than or equal to normal ambient swings?
l lYES l X lNO
..--- ------------- LF *tM'91^" '."9* '*SEEQ Wf_HffSJ@ 8($1, 0]_WfRSf [q_PMJfS_S_IS_C9MJfE[E{
NED/
(c) is the valve oriented in such a way as to trap steam condensate ops in the bonnet when closed?
l lYES l X lNO ops (d) Does the valve, which is normally or occasionally exposed to cool fluid, potentially experience body temperature changes from fluid temperature conditions in the attached or adjacent piping?
l X lYES l lNO 1125/9810:06 AM Rev.3 rue =xts
GENERIC LETTER 95-07 SCREENING FORM l
In l
' Valve Mark No.: MOV-SI-869A Gate style: FLEX WEDGE j
==
Description:==
CH PUMP TO RCS HOT LEG ISOL Page 3 of 4
- (cont'd)
(e) Does the valve, which is normally exposed to ambient conditions.
ops potentially experience hot ambient conditions (such as a high energy line break) prior to having to open?
l X lYES l lNO j
IF Sic),fd}orie) IS *YES*, TM VAL VE htA Y BE SUSCEPTIBLE TO 94tESSLM9E LOCKING.
i l
ADDITIONAL INFORMATION/ COMMENTS IN REGARD TO ABOVE QUESTIONS:
i
(
2a,b Valve is NSA shut. Required to be opened manually during transfer to recirc phase of S.I. Stroked to open & closed position per OST 1.1.10 durina cold shutdown at least once per refuelina.
3 4
l 4d,e,5c,d,e Valve is not opened until 14.5 hrs after LOCA, and is not re-closed, per ES 1.3.
i i
}
7c,d Valve normally exposed to high pressure fluid on upstrepen side due to charging pumps.
4
}
Durina accident this pressure would be lower,100 osin above RCS pressure.
f Sc,d Valve normally @ ambient condition. During recirculation phase is subject to hot cnmt sumo water (about 150F 7) when open. Is not re-closed.
I J
s
.l 8e Potentially subject to HELB phenomena, located in penetration ares 'A'.
High j
temp sensors in area will isolate hiah enerov breaks.
I i
l
SUMMARY
1 1
i VALVE MAY BE SUSCEPTIBLE TO HYDRAULIC PRESSURE LOCKING due to 7(c),(d)
VALVE MAY BE SUSCEPTIBLE TO THERMALLY INDUCED PRESSURE LOCKING due to 8(c),(d),(e)
SEE ATTACHED (Page 4) EVALUATION 1/25/M 10 05 AM Rev.3 w=us
GENERIC LETTER 95-07 SCREENING FORM l142 Vdvs Mark No.: MOV-SI-869A Gato style: FLEX WEDGE
==
Description:==
CH PUMP TO RCS HOT LEG ISOL Page 4 of 4 SCREENING EVALUATION:
MOV-SI-869A This normally closed valve is not considered susceptible to GL95-07 PL or TB. The valve could be manually opened to initiate a simultaneous cold leg and hot leg recirculation 14.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> after SI cold leg recirculation has taken place. This valve was evaluated for PI/fB susceptibility by TER-8887 in 1994. See Reference (A).
Review of the TER to the PL and TB susceptibility criteria of GL95-07 reveal that this valve is not susceptible to the phenomenon.
References:
(A)
TER-8887, " Evaluate the Susceptibility of MOV-SI-869A and 869B to the Pressure Locking and Thermal Binding Phenomena ofINPO SOER 84-7",06/27/94 (B)
EOP ES-1.4, " Transfer to Simultaneous Cold Leg and Hot Leg Recirculation", Issue 1, Revision 2 Rev.3
4 GENERIC LETTER 95-07 SCREENIN2 FORM l
In 1
. Valve M:rk No.: MOV-SI-869B Gata rtyl:: FLEX WEDGE s
==
Description:==
CH PUMP TO RCS HOT LEG ISOL Page 1 of 4 3
~
NED 1 Vahre ApplicabiEty:
Power Operated Gate Valve Safety Related f
I 2 Function l
ops (a) Does the valve have a safety-related function to OPEN and is
)
]
the valve either normally or occasionally closed during normal, j
system test, or accident scenarios?
l X lYES l lNO
)
f ops (b) Does the valve have to open during surveillance testing or post maintenance activity?
l X lYES l lNO
{
if ste)0ReiIS 'YES*, PROCEED WITH TW SCMENNG PROCESS, OTWRWISE VALVEIS NOT AMUCABLE.
3 Component Level Criteria for Theemal Binding i
NED (a) Does the valve have a design feature that mitigates or precludes thermal binding? (e.g. Parallel Disk) l lYES l X lNO l
j IF 3(a)IS 'YES*, IGNORE TWI%4AL BINDING, 00 TO STEP 6.
1 j
4 System Screening / Evaluation Criteria for Stem Effect Thermal Sinding NED (a) Does the valve actuator have a compensating spring for stem growth?
l lYES l X lNO NED (b) is the actuator sized for unseating thrust which takes into account i
the stem growth?
l-lYES l X lNO ops (c) Does a procedure exist that requires cyc5ng the valve at cooling I
j Delta T intervals of 20-50 degrees F?
l lYES l X lNO 1
l
. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.!E.t."h*U_Wc.! d?_*bo_~_?2EERE%MTP_"_'!.dk 2W"s!_02_rg gW_StigN 6.us.
[
ops (d) is the valve closed hot (>200F), with no subsequent cooldown, then l
required to open?
l lYES l X lNO i
j ors (e) is the hot valve (>200F) required to close while the system / valve is l
i being cooled down and signaled to open before the valve cools down (i.e., not completely cooled down)?
l lYES l X lNO i
IF did)OR(e)is *YES*, TM VALVE MA Y BE SUSCFPTIBLE TO TWintAL BINDING, CONTINW WITH QUESTION 6te).
5 System Screening / Evaluation Criteria for Wedge Effect Thermal Sinding ll NED (a) la the actuator sized for unseating thrust which takes into account I
thermal binding of the wedge?
l lYES l X lNO j
ops (b) Does a procedure exist that requires cycling the valve at a cooling i
Delta T interval of approximately 20 50 degrees F?
l lYES l X lNO I
. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _IF_6_fe)A_hD_(b_) AM_ _'N0_*, P_R_OC_E_ED_ WI_TH_ QU_E_ST_IO_N_6_fc_), O T_WR_WIS_E_G_O_T_O _ST_E_P _
1 I
ops (c) is the valve closed hot followed by a cooldown of >100 degrees l
and then required to open?
l lYES l X lNO ops (d) is the hot valve required to close while the system / valve is cooling down to > 100 degrees F (i.e., subject valve closure terminates l
cooling) and required to open after the valve has cooled down?
l lYES l X lNO 1
i i
times 1o:o7 m j
Rev.3 nwmms l
4
[
GENERIC LETTER 95-07 SCREENING FORM l
143
. valva Mark No.: MOV-SI-869B G te style: FLEX WEDGE
==
Description:==
CH PUMP TO RCS HOT LEG ISOL Page 2 of 4 5 (cont'dl i
ops (e) Can a temperature gradient of > 100 degrees F develop across the l
valve after it is closed and is the valve then required to be opened?
l lYES l X lNO l
l IF 6(c),fd10M(elIS 'YES*, THE VALVE MAY BE SUSCEPTl8LE TO THEb9HAL BINDING, GO TO STEP 6.
l 6 Component Level Criteria for Pressure Locking NED to) is the valve a solid wedge Gate valve?
l lYES l X lNO j
NED (b) Does the valve have a design feature that mitigates Pressure Locking (hole in the disk, bonnet bypass, bonnet relief, air trap, etc.)?
l lYES l X lNO NED If YES, What is it?
w einforelIS *YES*, IGNORE PRESSIME LOCKbNG, MFOCESS IS COMMETE.
7 System Screening / Evaluation Criteria for HydrauEc Pressure Locking NED/
(al Has valve inservice testing (e.g. MOVATS Testing) during MEAD operation closely duplicated the hydraulic pressure locking condition and been shown to operate successfully?
l X lYES l lNO NED (b) la the actuator si20d for maximum expected bonnet pressure for the hydraulic pressure locking condition?
l lYES l X lNO l
U*!L* *N0
- qgCEgo.wrzu qqSrp_NjZeL 2LM"Ms.E_GjfQ QyE,S[lgN,0Q ops (c) is the valve normally or occasionally exposed to high pressure fluid, and is the attached piping potentially depressurized prior to valve actuation?
l X lYES l lNO l
ops (d) is the valve, which is normally exposed to low pressure fluid, potentially subjected to high pressure fluid due to back leakage from a high pressure source and is the attached piping potentially depressurized prior to valve actuation?
l lYES l X lNO l
IF 7(elorld)IS 'YES*, THE VALVE MAY BE SUSCEPTIOLE TO MlESSlnE LOCKING, CONTINUE WrTH QUESTION Diel.
8 System Screening / Evaluation Criteria for Thermagy induced Prosaure Locking NED (a) is the actuator sized for maximum expected bonnet pressure due to the thermal pressure locking condition (i.e., temperature in the bonnet)?
l lYES l X lNO OPS (b) Are temperature changes associated with this valve less than or equal I
to normal ambient swings?
l lYES l X lNO
LF_0@@old@LA_Q *N0*g_Ml0f[Efff_H_QQE_STigN B($1, 0]_NER, y![S((q_Ml0_CfSS,1$ CpMyy_E,)
NED/
(c) is the valve oriented in such a way as to trap steam condensate Ops in the bonnet when closed?
l lYES l X lNO l
ops (d) Does the valve, which is normally or occasionally exposed to cool fluid, potentially experience body temperature changes from fluid temperature conditions in the attached or adjacent piping?
l X lYES l lNO 1!25/9810:07 AM Rev.3 rummutms l
i
e sa J
w-,-
CENERIC LETTER 95-07 SCREENING FORM l
us i
' Valve Mark No.: MOV-SI-869B Gate style: FLEX WEDGE
==
Description:==
CH PUMP TO RCS HOT LEG ISOL Page 3 of 4
)
l 8 (cont'd) ops (a) Does the valve, which is normally exposed to ambient conditions, potentially experience hot ambient conditions (such as a high energy line break) prior to having to open?
l X lYES l lNO J
{
if 8(c),fdiorfe)IS *YES*, THE VALVE MAY BE SUSCEPTIBLE TO 14tESSUSlE LOCKING.
ADDITIONAL INFORMATION/ COMMENTS IN REGARD TO ABOVE QUESTIONS:
2a,b Valve is NSA shut. Required to be opened during transfer to recire phase during LOCA. Stroked to open & closed position per OST 1.1.10 at least once per refuelina.
l j
4d,e,5c,d,e Valve is not opened until 14.5 hrs after a LOCA and is not re<losed. Will be subjected to enmt sumo temp (150-200F),
t.
7c,d
,V.'ve is normally exposed to charging pump discharge pressure during j
accident may see 100 psia charcina pump to RCS delta P.
Sc,d Valve normally @ ambient temp. Exposed to higher enmt sump temp during recire. phase from enmt sump water when open (about 150F ?). Is not re-closed.
1 i
8e Potentially subject to HELB temps, valve located in SFGDS penetration area 'C'.
i Auto closure on Hich Energy pipina should occur on hi temp.
l
SUMMARY
I VALVE MAY BE SUSCEPTIBLE TO HYDRAULIC PRESSURE LOCKING due to 7(c),(d)
VALVE MAY BE SUSCEPTIBLE TO THERMALLY INDUCED PRESSURE LOCKING due to 8(c),(d),(e)
SEE ATTACHED (Page 4) EVALUATION 1/25/9810:07 AM Rev.3
== n 8
GENERIC LETTER 95-07 SCREENING FORM l143 Vdv3 Mark N3.: MOV-SI-869B Gats styb: FLEX WEDGE
==
Description:==
CH PUMP TO RCS HOT LEG ISOL Page 4 of 4 SCREENING EVALUATION:
MOV-SI-869B l
This normally closed valve is not considered susceptible to GL95-07 PL or TB. The valve could be manually opened to initiate a simultaneous cold leg and hot leg recirculation 14.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> after SI cold leg recirculation has taken place. This valve was evaluated for PL/TB susceptibility by TER-8887 in 1994. See Reference (A).
Review of the TER to the PL and TB susceptibility criteria of GL95-07 reveal that this valve is not susceptible to the phenomenon.
References:
(A)
TER-8887, " Evaluate the Susceptibility of MOV-SI-869A and 869B to the Pressure Locking and Thermal Binding Phenomena ofINPO SOER 84-7",06/27/94 (B)
EOP ES-1.4, " Transfer to Simultaneous Cold Leg and Hot Leg Recirculation", Issue 1, Revision 2 i
i e
Rev.3 ExE
l l
i l
To Responses to the Request for AdditionalInformation Generic Letter 95-07 Beaver Valley Power Station, Unit Nos.1 and 2 l
l i
4 5
l'. -.
5 TECHNICAL EVALUATION REPORT ON THE POTENTIAL OCCURRENCE OF l
l PRESSURE LOCKING OR THERMAL BINDING IN MOV-SI-869A and 869B I
i I
SYN 0PSIS A technical evaluation to determine the susceptibility of 3-inch motor i
operated valves MOV-SI-869A and 869B to the pressure locking and thermal binding phenomenan discussed by INP0 SOER 84-7 for BVPS Unit l_(Ref. A) has been performed. The possibility of thermal binding of these valves J
is not present.
A negligible possibility of pressure locking of the valves vill always be present_ as a differential pressure exists between the normal system arrangement and accident _ system arrangement operational pressures at the valves.
However no valve modification or procedural change is recommended as the possibility of pressure locking is very remote and the consequence of these valves being difficult to open does not affect the ability to safely shutdown and cooldown the plant if so required.
i 4
)
i I
1 j
1 i
L i
l 1
l DESCRIPTION 1
l l
MOV-SI-869A and MOV-SI-869B are 3-inch, 1500 pound pressure class, l
stainless steel, motor-operated flexible vedge gate valves.
MOV-SI-869A is located in the Safeguards pipe penetration
'A' cubicle at elevation 724 feet.
MOV-SI-869B is located in the Safeguards pipe penetration -
'C' cubicle at elevation 724 feet.
The valves vere manufactured to the Velan Engineering Co. drawing 88405-2, Rev.
G, and supplied to DLC by the Vestinghouse design specifications 955815 Rev. O and 676258, Rev. 2.
The valves have two shared functions.
First, MOV-SI-869A is the outside l
Containment isolation valve for safety injection penetration No. 7 and MOV-SI-869B is the outside Containment isolation valve for safety 1
l injection penetration No. 33.
- Second, during the later part of the recirculation phase of a safety injection, the valves can be manually opened (via the Control Room) to initiate simultaneous Reactor Coolant l
System cold leg and hot leg recirculation.
Opening MOV-SI-869A allows the redundant SIS flow path into the RCS cold legs to bypass that path and flow directly into the RCS hot legs.
i Opening MOV-SI-869B allows the SIS vater that had been flowing through l
the BIT tank and hence to the RCS cold legs to bypass the tank and flov directly into the RCS hot legs.
MOV-SI-869A is connected to 3-inch pipe SI-130-1503-02 on its inlet and 3-inch SI-130-1503-01 on its outlet.
Inlet pipe-SI-130 is in turn directly connected to the charging pump CH-P-1A,B,C discharge header 4-inch CH-76-1503-02 (via pipe SI-128).
I MOV-SI-869B is connected to 3-inch pipe SI-133-1503-02 on its inlet and 3-inch SI-134-1503-01 on its outlet.
Pipe SI-133 is in turn directly connected to the charging pump discharge header 4-inch CH-72 (via pipe SI-75).
MOV-SI-869A&B are not valves used to support normal operation of Unit 1.
j Therefore establishing normal system pressure and temperature at these valves requires the following discussion.
MOV-SI-869A&B are initially stroked open and close under plant mode 5 conditions to fill the SIS with RUST vater.
Refer to procedure 11.4J l
' Filling And Venting The Safety Injection System'. RVST vater is then I
between 45'F and 55'F and contains 2000-2100 ppm boron.
Mode 5 conditions of the SIS then remains the RVST head pressure, process temperature remains that supplied by the RUST.
During normal plant operation MOV-SI-869A&B and their process environment stabilize at the normal Safeguards ambient temperatures.
The valves are physically located far enough from both the charging pumps on their inlet (150 feet of 3 inch and 4 inch pipe for MOV-SI-869A and 205 feet of 3 inch and 4 inch pipe for MOV-SI-869B) and the containment process environment on their outlet (190 feet of 2, 3, 4 and 6 inch pipe prior to reaching the large bore RCS pipe) as to be independent of the normal operating temperatures of these two heat sources.
Refer to the plant layout references F thru V for further details.
Operating Manual 1.44B defines the Safeguards environment as l
120*F maximum, but the more normal temperature is 80*F as it was Apri.
l 14, 1994 in the
'A' penetrations cubicle.
l During normal plant oparation the upstrec.m side of MOV-SI-869A&B are subject to the normal charging system pressure of 2500 PSIG (Ref. AA).
The downstream side of each valve connects to the RCS.
There are two sets of check valves between each MOV and the RCS.
Ideally these check l
valves are leak tight and the MOVs are subject to a differential pressure of 2500 PSIG.
Realistically all check valves leak somewhat, however for the purpose of this evaluation, downstream pressure shall be considered zero PSIG.
The MOV-SI-869A&B flexible vedges are assumed to flex under these conditions and introduce 2500 PSIG vater into their bonnet cavities. The valves have a capped valve stem leak-off therefore the pressure could remain in the bonnet cavity.
To conclude the last two paragraphs; the normal system conditions of MOV-SI-869A&B are 80*F, 2500 PSI differential pressure, 2500 PSIG on their inlet.
ACCIDENT CONDITIONS MOV-SI-869A&B could be used to help mitigate the very long term effects of a severe plant accident.
E0F El
' Loss Of Reactor Or Secondary l
Coolant' and ECA-2.1
' Uncontrolled Depressurization Of All Steam Generators' describe inside Containment accidents so severe that the Safety Injection System and Containment Depressurization System have dumped the contents of the RVST into Containment (vater level of the RUST has dropped to the 19 foot level).
The SIS accumulators have emptied, the BIT inlet and outlet isolation valves (MOV-SI-867A,B,C,D) have opened so that tae charging pumps, nov acting as high head safety injection pumps, have emptied the BIT by pushing its contents and that of the RUST into the RCS cold legs.
Most of this highly borated water flows into the containment sump.
The SIS injection phase is complete, and the SIS recirculation phase begins.
In the recirculation phase of SIS the high head pumps line up to receive the discharge of the LHSI pumps which in turn have been valved to take suction from the containment sump.
At this point the E0P sends the user l
to ES-1.3
' Transfer To Cold Leg Recirculation'.
Sump vater shall continue to be pumped through the BIT and its isolation valves into the l
RCS cold legs.
Step 4 of ES-1.3 opens MOV-SI-836.
Flow through MOV-SI-836 becomes a second or redundant pumping path for containment sump
(
vater to enter the RCS cold legs.
l 14.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> into the accident the E0P user proceeds to ES-1.4 ' Transfer To Simultaneous Cold Leg And Hot Leg Recirculation'.
Valves circulating Containment sump water to the BCS cold legs, MOV-SI-867A,B and MOV-SI-836, shall be closed. Valves MOV-SI-869A&B shall be opened allowing the two high head pumps then operating to pump recirculating SI into the RCS j
hot legs.
Flov through MOV-SI-869A bypasses MOV-SI-836 (though sharing i
l much of the same inlet pipe) and becomes the redundant RCS hot leg l
recirculation flovpath.
Flov through MOV-SI-869B bypasses the BIT tank and becomes the primary RCS hot leg recirculation flow path.
Reference pipe isometerics (Ref. L-V) illustrate the flow arrangement.
The ambient temperatures of MOV-SI-869A&B could have stayed at their 80*F condition or, at vorst, could have risen to that of the containment sump water temperature.
The sump water temperature has dropped below t
150*F by the time SIS enters recirculation (Ref.
X).
Differential temperature between the MOV-SI-869A&B valve bonnets and their bodies is negative, if it exists at all, i.e.
the valve bonnet is cooler than the valva body. Therefore INP0 SOER thsrmal building of thase valves is not possible. R2 call that tha driving machanism for thsrmsl binding is to have the fluid process temperature in the valve bonnet substantially higher than that of the valve body.
This differential temperature supports differential thermal expansion of some valve subcomponents that tend to lock the valve disc in its closed position.
Vith the failure of the RCS pressure boundary, process pressure on MOV-SI-869A&B has dropped belov 2500 PSIG.
One or two HHSI pumps could be.
available for SIS recirculation, but both the licensing technical specifications and the UFSAR system description state that just one operable train of HHSI and LESI pumps is required to recirculate SIS if the conditions of the RCS warrant a HHSI pump at all (Ref. V,Y).
Containment sump water flov through both the MOV-SI-869B pipe system that is bypassing the BIT and the redundant MOV-SI-869A pipe system has been adjusted so that flov quantity and delivered flow pressure are the same. OST 1.11.14 ' Safety Injection System Full Flow Test' (Ref. AI) has purposely adjusted manual valves in these two subsystems to achieve such results. ~ Also, the OST has adjusted the manual valves to prevent a HHSI pump from full runout.
Maximum flov through each path or from each pump is approximately 510 gpm.
At this flow rate pressure head delivered by the pump is around 2400 feet, or 1040 PSIG (Ref. E).
Vith one LHSI pump running, system pressure at M0V-SI-869A&B is an approximate 1150 PSIG (Ref. AB).
This value is 1350 PSI below normal system process pressure at the valves.
INP0 SOER pressure locking of MOV-SI-869A&B vould be a possibility if the 1350 PSI differential pressure just determined were to be kept within the bonnet cavity of the applicable valve and that this differential pressure was a value that could not be overcome by the valve's operator. This ideal situation based upon a vorst case system scenario is not endorsed by this technical evaluation.
It's expected that possible differential pressure across the bonnet cavity of either MOV-SI-869A or 869B vill be reduced to zero differential pressure by the following circumstances:
- The valve packing chamber on both MOV-SI-869A&B provides a pressure relief path.
The valves packing leaks continuously.
Recent MVRs 007845, 012284, 024918 and 029602 on MOV-SI-869A and MVRs 901625, 005341, 010688 and 029603 on MOV-SI-869B have unsuccessfully attempted to completely stop the leaks.
Its clear that this packing chamber as has been described by the EPRI design allows continuous leakage valve stem packing report (Ref. AF).
Note that this finding is consistent with that determined for MOV-SI-836 (Ref. A0), an identical Velan valve with a leaking packing chamber.
- Ear.h MOV-SI-869A&B valve body is experiencing leakage across the disc under containment penetration testing conditions.
Refer to BVT 1.3 -
1.47.11 ' Safety Injection And Charging System Containment Penetration Integrity Test' testing performed on February 17, 1988, November 13, 1989, June 9, 1991 and May 30, 1993.
Leakage rate observed is aceptable and,no valve body modification is planned.
- The NRC report on pressure locking and thermal binding (Ref. B) did not identify HHSI MOVs in liquid service as susceptible to the phenomenon nor have Velan valves in the indust.ry been identified as involved in any pressure locking or thermal binding event.
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Note that in ordar for the pressure locking occurrcnce to lock a gate valve disc in position, no leakage is allowed out of the valve bonnet
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because water is essentially incompressible.
The Velan valves exhibit sufficient leakage, either through the packing chamber or around the disc to prevent such an incident.
CONSEQUENCE OF EITHER MOV-SI-869A OR 869B BEING STUCK CLOSED UFSAR 6.3.1.2
'ECCS Single Failure Criteria Compliance' states that
'During the long term cooling period following a LOCA, the emergency core ecolic.; flow paths shall be separable into two subsystems, either of which can provide minimum core ceoling functions and return spilled water from the flow of the containment back to the RCS.'
This paragraph is discussing the SIS redundant recirculation flow paths to the RCS cold legs.
It is saying that one of the redundant recirculation flow paths may be lost without consequence to the established plant design and accident analysis.
This position is supported by Technical Specifications which describes an independent ECCS subsystem as consisting of one LHSI pump, one HHSI pump and the ability to take suction from the containment sump.
The availability of just one SIS recirculation flow path is also discussed in the LOCA accident analysis in UFSAR Section 14.3.1 where it is stated that
' Minimum Safeguards Emergency Core Cooling System capability...' has been assumed in these analyses.
If an accident mitigation effort has proceeded to the point where implementation of EOF ES-1.4 can be considered and MOV-SI-869A&B opened then its obvious that two SIS recirculation flow paths have been established.
This situation by itself is enough to return the plant to a safe standby status. Vere there to be difficulty in using either MOV-SI-869A or 869B then plant recovery would simply proceed without them.
There vould be no detrimental consequence to full recovery from an accident.
Lastly, DLC has prepared the Ref. AJ report
' Risk-Based Equipment Prioritization For Beaver Valley Power Station Unit l'.
This report provides a risk importance rank for components necessary to safely shutdown the plant. The risk associated with either MOV-SI-869A or 869B is so small that they weren't even listed in the report. That vould make their risk importance factor less than 1.0E-09 which is about that of some listed but low ranking components. The current BVPS Unit 1 core damage frequency is 2.lE-04 per year.
CONCLUSION l
MOV-SI-869A&B shall be considered independent of the INP0 SOER 84-7 pressure locking or thermal binding behaviors and shall not be modified l
for such events at BVPS Unit No. 1.
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REFERENCES l
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Regulatory Documents A. INFO SOER 84-7 ' Pressure Locking And Thermal Binding Of Gate Valves' l
December 14, 198 l
B. NRC NUREG-1275 Vol.
9 ' Operating Experience Feedback Report
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Pressure Locking And Thermal Binding of Gate Valves' l
C. NRC Generic Letter 89-10 ' Safety Related Motor-0perated Valve Testing And Surveillance' l
Vendor Technical Information D. Dvg. 8700-06.048-0005G ' Forged Bolted Bonnet Motor Operated Gate Valve' [Velan Engineering Co. dvg. 88405-2, Rev. G) l E. Tech. Manual 8700-02.032-0026 ' Charging Pumps' Rev. AB Location Information F. VOND 8700-RM 407-1 ' Chemical and Volume Control System' Rev. 5 G. VOND 8700-RM-411-1 ' Safety Injection System' Rev. 4 H. VOND 8700-RM-406-1 ' Reactor Coolant System' Rev. 2 I. Flow Diagram 8700-RM-39A ' Charging and Volume Control System' Rev. 35 J. Flow Diagram 8700-RM-41A ' Safety Injection System' Rev. 28 K. Flow Diagram 8700-RM-41B ' Safety Injection System' Rev. 24 L. Pipe Iso 8700-6.24-200 ' Reactor Containment - High Head Safety Injection' M. Pipe Iso 8700-6.24-221 ' Reactor Containment - Cubicle No. 2' l
N. Pipe Iso 8700-6.24-222 ' Reactor Containment - Lov Head Safety Injection' O. Pipe Iso 8700-6.24-266 ' Charging And Volume Control System' P. Pipe Iso 8700-6.24-267 ' Charging And Volume Control' l
- 0. Pipe Iso 8700-6.24-272 ' Charging And Volume Control' R. Pipe Iso 8700-6.24-275 ' Reactor Containment Tunnel Piping' l
l S. Pipe Iso 8700-6.24-367 'High Head Safety Injection System' l
T. Pipe Iso 8700-6.24-368 'High Head Safety Injection System' U. Pipe Iso 8700-6.24-376 ' Reactor Containment - Lov Head Safety Injection' l
V. Pipe Iso 8700-6.24-377 ' Reactor Containment Annulus Piping' l
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UFSAR and Technical Specifications V. UFSAR 6.0 ' Engineered Safety Features' Rev. 11 including 6.3 ' Emergency Core Cooling System' 6.4 ' Containment Depressurization System' i
Table 6.3.12 ' Normal / Accident Functions Evaluation' Table 6.3.1 ' Single Active Failure Analysis.ECCS' X. UFSAR 14.0 ' Safety Analysis' Rev. 11 including l
14.2 ' Standby Safeguards Analysis' 14.3 ' Loss Of Coolant Accident' Figure 14.3-58 ' Containment Sump Analysis LOCA' Y. Technical Specifications as Amended February 17, 1994 including i
3.1.2.7 ' Borated Vater Sources - Shutdovn i j
3.1.2.8 ' Borated Vater Sources - Operating' i
3.5.2 'ECCS Subsystems Tavg > 350*F' 3.5.3 'ECCS Subsystems Tavg i 350*F' 3.5.4.1.1 ' Boron injection Tank' 3.6.3.1 ' Containment Isolation Valves' I
Operating Manuals and Emergency Operating Procedures
- 2. OM 1 ' Reactor Control and Protection' Issue 2, Rev. 8 AA. OM 7 ' Chemical Volume and Control System' Issue 4, Rev. 3 AB. OM 11 ' Safety Injection System' Issue 3, Rev. 2 including Procedure 11.4J ' Filling And Venting The Safety injection System' AC. E0P E-1 ' Loss Of Reactor Or Secondary Coolant' Issue 1A, Rev. 2 AD. E0P ECA-2.1 ' Uncontrolled Depressurization Of All Steam Generators' AE. E0P ES-1.3 ' Transfer To Cold Leg Recirculation' Issue 1A, Rev. 2 AF. E0P ES-1.4
' Transfer To Simultaneous Cold Leg And Hot Leg i
l Recirculation' Issue 1, Rev. 2 Test Documentation AG. BVPS Unit 1
' Inservice Testing (IST)
Program For Pump And Valves' Issue 2, Rev. 11 AH. BVT 1.47.11
' Safety Injection and Charging System Containment l
Penetration Integrity Test' including Test Reports dated February 17, l
1988, November 13, 1989, June 9, 1991, May 30, 1993 AI. OST 1.11.14 ' Safety Injection System Full Flov Test' Issue 2, Rev. 3 including test report for April 13, 1994 i -.
1 9
Others
.AJ. Risk - Based Equipment Prioritization-For Beaver Valley Power Station Unit 1, Rev. O AK. CMP-75-Velan Gate-2M, Issue 4, Rev. O AL. Vestinghouse Specification 955815 ' Globe Valves' Rev. O AM. Vestinghouse Specification 676258 ' Motor Operated Valves' Rev. 2 AN. EPRI NP-5697 ' Valve Stem Packing Improvements' May 1988 A0. TER-8763 ' Susceptibility of MOV-SI-836 to Pressure Lock and Thermal l
Binding' Rev. O r
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To Responses to the Request for AdditionalInformation Generic Letter 95-07 Beaver Valley Power Station, Unit Nos. I and 2 l
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CENERIC LETTER 95-07 SCREENING FORM lios Valv3 Mark Ns.: MOV-RC-535 Gate style: FLEX WEDGE
==
Description:==
PORV PCV-RC-455C BLOCK Page 4 of 4 SCREENING EVALUATION:
MOV-RC-535 The PORV block valve has not demonstrated a susceptibility to GL95-07 PL or TB in its long service life to date, never-the-less, a review of possible operating scenarios for the valve reveal some susceptibility to TB. Susceptibility to PL isn't foreseen.
One (1) of three (3) block valves is normally open to provide a coolant flow path to its applicable PORV.
The Unit is run with the other two (2) block valves closed (Reference A).
Unit Technical Specification 3.4.11 requires that each PORV, and associated block valve, shall be operable.
Block Valves MOV-RC-535 and MOV-RC-537 contribute to the Units Cold Overpressurization Protection System (OPPS).
Normal differential pressure across an open block valve is O PSI. Normal differential pressure across a leak tight closed block valve would be 2235 PSL This pressure might enter the valve bonnet and pressurize it.
Hydraulic pressure lock is not a valve operational concern, as its operator was sized to maintain RCS pressure on its inlet, and ambient pressure on its outlet. Also, the valve won't experience thermal pressure locking as there doesn't exist a credible heat source to warm up a water filled bonnet independent of normal system operation.
An open valve exists in a water filled environment. This water is the loop seal for the j
applicable PORV, and provides a minimum of eight (8) feet of water filled pipe to the inlet of the block valve. This water will keep the block valve at an ambient temperature approximating 120*F. The block valve existing in this environment, or closed in this environment, would not be susceptible to TB, due to the absence of any differential temperature.
PORV leakage is annunciated by A4-25, which alarms at a setpont 200 F above ambient.
Such a condition would warrant closing an open PORV block valve. The loop seal may be lost, and the block valve could be exposed to temperatures at least 200*F above ambient. See Procedure AAQ from the Operating Manual describing A4-25.
The block valve is considered susceptible to thermal binding when the valve is closed to isolate a leaking PORV where the loop seal has already been lost. During PORV leak-through, the block valve might heat up considerably, and once the block valve is closed and the loop seal is re-established, would return to cooler ambient conditions.
NxIs Rev.3
EENERIC LETTER 95-07 SCREENING FORM lios Vdvs Mark N3.: MOV-RC-535 cata styb: FLEX WEDGE g
==
Description:==
PORV PCV-RC-455C BLOCK Page 4,of 4 SCREENING EVALUATION (cont'd):
MOV-RC-535 l
Presently, there are not any restrictions on PORV block valve usage (exclusive of Technical Specifications and IST valve testing). However, in otder to assure the Unit that these valves remain free of any GL95-07 PL or TB occurrences, NED proposes that new stroke requirements be imposed on the block valve. NED recommends that existing Operating Manual Procedure 6.4 AAQ, " Pressurizer Power Relief Line Discharge Temperature High", be revised to include a block valve stroke at least 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after the valve has been stroke closed and prior to declaring it operable. This will ensure that any j
potential thermal binding has been relieved.
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References:
(A) Operating Manual OM-6.0, " Reactor Coolant System" Issue 4, Revision 0 (B) Drawing 8700-06.048-0005J, "Velan Motor Operated Gate Valve" (C) Technical Specification 3.4.11, " Reactor Coolant System Relief Valves", Amendment No.188 (D) Isometric Drawing 8700-06.024-0350, " Pressurizer Spray and Safety Relief Tank Piping", Revision 6 l
(E) WOG, " Pressurizer PORV Block Valve 90 Day Evaluation Survey",
1996 l
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m.4. n.. ~
Rev.3 w"m8
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To Responses to the Request for Additional Information Generic Letter 95-07 Beaver Valley Power Station, Unit Nos. I and 2 i
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Barvar Vcilsy Powar Station Unit 1 10M-6.4.AAQ j
. Reactor Coolant System Issue 4 Revision 2 Operating Procedures Page AAQ 1 of 4
)
PRESSURIZER POWER RELIEF LINE DISCH TEMP HIGH A4-25 I
h PRESSURIZER j
POWER RELIEF LINE DISCH TEMP HIGH j
A4-25 1
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SETPOINTS: 200 'F Greater Than Ambient DISCONNECT SWITCH: 2-2234 (Bay 1)
SER POINT: 105 l
SER POINT ID: PRESSURIZER PWR RELIEF LNE DISCH TEMP HI 4
J INITIATING DEVICE: 26RC463X J
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CAUTION:
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- THE PREFERRED VALVE TO BE OPEN (DUE TO APPENDIX R CONSIDERATIONS) IS [MOV-1RC-537].
- THE LEAST DESIRABLE VALVE TO BE OPEN IS [MOV-1RC-535] BECAUSE PORV [PCV-1RC-455C] CAN BE OPEN AT PRESSURES BELOW THE SETPOINT DUE TO THE INTEGRAL FUNCTION OF THE PRZR PRESSURE MASTER CONTROLLER.
PROBABLE CAUSE NO.1 Actuation of Power Operated Relief Valve CORRECTIVE ACTIONS 1.
Check the following for indication of PORV actuation:
High relief line temperature as indicated on [TI-1RC-463], PRZR Pwr Relief Line a.
Temp. (VB-B) b.
Pressurizer pressure exceeded 2335 psig OR high rate of pressure increase as indicated on [PI-1RC-455,456 and 457], PRZR Press. (BB-B) 2.
If PRZR Press > 2335 psig, allow pressure to decrease to 2335 psig at which time the PORV should reseat.
B2avar Vcilzy Powsr Station Unit 1 10M-6.4.AAQ Rzacter Cosisnt Systsm issus 4 Rsvision 2 Operating Procedures Page AAQ 2 of 4 PRESSURIZER POWER RELIEF LINE DISCH TEMP HIGH A4-25 l
l Note: Pressurizer Power Operated Relief Valves can be isolated at power.
3.
If any [PCV-1RC-455C, (456), (455D)], PZR PORV Relief Viv has actuated AND PRZR Press is < 2335 psig THEN isolate the affected PORV by closing the associated
[MOV-1 RC-535, (536), (537)], PRZR PORV lsol MOV. (BB-8) a.
If any PORV is not closed. THEN place the control switch for the affected
[PCV-1RC-455C, (456), (455D)], PRZR PORV Relief Viv to CLOSE. (88-B)
PROBABLE CAUSE NO. 2 Power Operated Relief Valve leakage CORRECTIVE ACTIONS 1.
If PORV(s) have not actuated, check for high relief line temperature as indicated on
[TI-1RC-463], PRZR Pwr Relief Line Temp. (VB-B)
Note: Pressurizer Power Operated Relief Valves can be isolated at power.
2.
If a PORV is leaking, quantify the leakage. (Tech Spec 3.4.6.2) a.
If the PORV leakage has been determined to be unacceptable by the NSS, isolate the PORV by closing the associated [MOV-1RC-535 (536) (537)] PRZR PORV isol MOV. (Tech Spec 3.4.11) b.
Place one of the remaining PORVs in service.
3.
When PORV is isolated, monitor [TI-RC-463], PRZR Pwr Relief Line Temp, for decrease in temperature indicating flow path is isolated.
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i B2 vsr Vcilty Powxr Strtion Unit 1 10M-6.4.AAQ
, Reactor Coolant System issue 4 Revision 2 Operating Procedures Page AAQ 3 of 4 PRESSURIZER POWER RELIEF LINE DISCH TEMP HIGH A4-25 CAUTION: THE PRZR PORV ISOL MOV SHALL NOT BE STROKED IN THE FOLLOWING STEP IF THE PORV IS EXPERIENCING EXCESSIVE LEAKAGE (ie. > 10 GPM.)
(REFER TO TECH SPEC. 3.4.11)
Note:
- [MOV-1RC-535(536)(537)] is cycled open and immediRP closed in the following step to ensure no thermal binding of the valve wedge occurs due to thermal changes after the valve is closed.
- If operation of the PORV is needed during the 12 nour cooldown period, the PRZR PORV ISOL MOV can be opened to provide the flowpath to the PORV. If the PRZR PCRV ISOL MOV and the leaking PORV was operated during the cooldown, then the PORV leakage shall be re-evaluated. If the PORV continues to experience leakage, re-entry into this procedure is required and the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> cooldown period would be reinitialized.
- Cycling the PRZR PORV ISOL MOV following delays of > 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> is permitted.
The PRZR PORV ISOL MOV may be considered Operable following a successful stroke test.
4.
If [MOV-1RC-535(536)(537)], PRZR PORV ISOL MOV has been closed to isolate a Leaking PORV, allow at least 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for thermal stabilization.(C4
b.
If [MOV-1RC-535(536)(537)], failed to open OR > 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> elapsed from closing i
the MOV AND a test stroke of the MOV has not been completed. THEN declare the MOV inoperable and apply Tech Spec 3.4.11 applicable Action.
PROBABLE CAUSE NO. 3 instrument failure CORRECTIVE ACTIONS 1.
Verify PORV relief line temperature by checking [TI-1RC-463], PRZR Pwr Relief Line Temp. (VB-8) 2.
Check PRT temperature is not rising on [TI-1RC-471], Pressurizer Reflef Tank Temp.
(VB-B) 3.
Check PRT pressure is not rising on [PI-1RC-472], Pressurizer Relief Tank Press.
(VB-B) 4.
Verify PRZR pressure is being maintained as indicated on [PI-1RC-455,456, and 457], PRZR Press. (BB-8) 5.
If above actions have been verified, a failure of [TRB-1RC-463] device may have occurred.
6.
Initiate an MWR to troubleshoot and repair the cause of instrument failure.
m m 32sv r Valizy Powar Stttisn Unit 1 10M-6.4.AAQ
. Reactor Coolant System issue 4 Revision 2 Operating Procedures Page AAQ 4 of 4 PRESSURIZER POWER RELIEF LINE Dl3CH TEMP HIGH A4-25 l
1 REFERENCES A.
TECHNICAL SPECIFICATIONS l
1.
BVPS-1 T.S. 3.4.6.2 2.
BVPS-1 T.S. 3.4.11 l
B.
UPDATED FINAL SAFETY ANALYSIS REPORT NONE C.
COMMITMENTS j
I 1.
NRC GL-95-07 D.
ADMINISTRATIVE NONE E. VENDOR INFORMATION 1.
08700-07.070.004, Westinghouse Control and Protection Instrumentation System F.
DRAWINGS 1.
8700-RM-406-2, VOND Reactor Coolant System l
2.
8700-RE-21PP, Annunciator A4 Window Arrangement 3.
8700-RE-21PQ, Elementary Diagram Annunciator A4 SH 1 of 4 4.
8700-RE-21RG, Elem Diag Ann /Comparator Interposing Relays SH 3 of 6 G.
OPERATING MANUAL
,4 1.
OM-1.6.1, Reactor Coolant System - Description 2.
10M-6.2, Reactor Coolant System - Precautions, Limitations and Setpoints 3.
10M-6.31RC Valve List H.
PLANT MODIFICATION NONE I.
OTHER 1.
Computer input / Output List 2.
OMDR 1-94-2001 (Issue 4. Revision 1) l 3.
OMCR 1-96-0503. EM-111626, NRC GL 95-07 (Rev. 2) l l
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To Responses to the Request for Additional Information Generic Letter 95-07 Beaver Valley Power Station, Unit Nos. I and 2 l
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Page 3 of Attachment to 180-Day Response to Generic Letter 95-07 The valves that were determined susceptible to at least one of the GL 95-07 PL or TB criteria, and the resolution of their susceptibility concerns, are described below.
BVPS Unit No.1 MOV-SI-867A, B, C, D These safety injection system (SIS) valves isolate the boron injection tank (BIT) from normal Unit operating systems. MOV-SI-867A & B isolate the BIT inlet from chemical and volume control system (CHS); MOV-SI-867C & D isolate the BIT outlet from the reactor coolant system (RCS). MOV-SI-867A & B were determined susceptible to hydraulic pressure locking during a previous evaluation in 1994 and have been modified through disc drilling to negate the PL susceptibility. MOV-SI-867C & D were determined susceptible to GL 95-07 pressure locking. The present operability of the C and D valves is assured by large thmst j
margins as shown by dynamic testing at 100% of design differential pressure. MOV-SI-867C l
& D valves will be modified similar to the 867A & B valves during Unit No. l's eleventh j
l refueling outage and twelfth refueling outage, respectively, to prevent potential future degradation.
l MOV-SI-860A, B These SIS valves open during the transition from SIS injection phase to SIS recirculation phase in order to provide a flowpath from the containment sump to the suction of the Low Head Safety Injection pumps. The valves were determined susceptible to hydraulic pressure locking during a previous ' evaluation, and determined potentially susceptible to thermal binding during the GL 95-07 evaluation.
The hydraulic pressure locking concern was eliminated when the valves were confirmed to have an installed relief path between each valve's bonnet and its upstream pipe.
A containment sump temperature analysis in 1995 determined that differential temperatures which could potentially be experienced by the valves are within the screening criteria values; hence thermal binding will not occur.
MOV-RC-535, 536, 537 These reactor coolant systen valves can be used to isolate the power operated relief valves (PORVs) during normal plant operation to isolate a leak. The valves' safety function is to close, but it may be necessary to open them to restore an isolated PORV to service. The valves are susceptible to GL 95-07 thermal binding. PORV block valve TB susceptibility will be negated by revising existing valve operating procedures to require an additional opening and closing stroke (prior to declaring the block valve operable) whenever a block valve has l
been closed to isolate a leaking PORV. The procedure revision will be completed by April 30, 1996. This additional valve movement will occur after thermal stabilization, so that it will i
verify component operability and the absence of any GL 95-07 PL or TB phenomena. Note Page 4 of Attachment to 180-Day Response to Generic Letter 95-07 1
that 2 of 3 of these valves are presently closed, but they have been stroked during operational surveillance tests to confirm no thermal binding exists.
Hydrotest Boundary Valves l
Any closed power-operated flex-wedge gate valve used as a hydrotest pressure boundary is considered potentially susceptible to GL 95-07 hydraulic pressure locking. Therefore, in order to alleviate this potential concern, applicable hydrotest procedures will either confirm operability of such valves following any pressurized test or provide sufficient time for pressure bleed-off. The administrative guidelines which are used to prepare the hydrotest procedures will be revised by July 31, 1996, to include the appropriate instructions for procedure preparation.
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BVPS Unit No. 2 l
2RHS-MOV701 A,701B,702A,702B l
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l These four residual heat removal valves provide redundant system isolation between the RCS l
loop A hot leg and the inlet to the residual heat removal system (RHS). The valves were determined susceptible to hydraulic pressure locking during a previous evaluation.
During the Unit's construction phase, the RHS inlet valves had the upstream side of their I
flexible wedges drilled through to allow a bonnet relief path. The drilled wedges relieve hydraulic pressure locking.
2RHS-MOV720A, B These residual heat removal discharge valves provide system isolation between the two RHS l
loops and RCS loop B and C cold legs. The valves are susceptible to GL 95-07 hydraulic i
pressure locking.
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l Evaluation of system operation requirements determined that sufficient time will elapse between the occurrence of the hypothetical pressurized bonnet and the necessity to stroke the l
valve so that GL 95-07 hydraulic pressure locking will bleed away. Therefore, the RHS l
l discharge valves will not be modified.
2 SIS-MOV867A, B, C, D These safety injection system valves provide redundant system isolation between the chemical and volume control system and the RCS during normal plant operation. 2 SIS-MOV867A &
B are system inlet isolation valves; 2 SIS-MOV867C & D are system outlet isolation valves.
Valves 867A & B were determined susceptible to hydraulic pressure locking during a previous evaluation. Valves 867C & D were determined susceptible to GL 95-07 pressure locking.
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