ML20216C367
| ML20216C367 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 05/08/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20216C356 | List: |
| References | |
| NUDOCS 9805190240 | |
| Download: ML20216C367 (11) | |
Text
no k
UNITED STATES y
s j
NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2066M001
.....,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATEDTO AMENDMENT NOS. 59 AND 45 TO t
FACILIW OPERATING LICENSE NOS. NPF-87 AND NPF-89 TEXAS UTILITIES ELECTRIC COMPANY COMANCHE PEAK STEAM ELECTRIC GTATION. UNITS 1 AND 2 DOCKET NOS. 50-445 AND 50-446
1.0 INTRODUCTION
By application dated April 9,1998, (TXX-98107), Texas Utilities Electric Company (TU Electric /the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos. NPF-87 and NPF-89) for the Comanche Peak Steam Electric Station (CPSES), Units 1 and 2. The proposed changes would allow on a one-time basis, the verification of the proper operation of the Unit 2 load shed seal-in contacts and the diesel generator trip bypass contacts at power and crediting performance of Surveillance Requirements (SR) 4.8.1.1.2f.4) and 4.8.1.1.2f.6), at power as opposed to "during shutdown" as currently required by those SR. The proposed amendment would also allow on a one-time basis the verification of the proper operation of the Unit 2 lockout relays and contacts to be deferred until the startup from the Unit 2 fourth refueling outage (2RFO4) or earlier outage to at least MODE 3.
1 A'though the above SRs apply to both Units 1 and 2, these surveillances were adequately I
performed for Unit i during its recent shutdown. Therefore, the license amendment request is only applicable to Unit 2 and is administrative for Unit 1.
In the application dated April 9,1998, the licensee indicated that Unit 1 Train A lockout relays i
and contacts was scheduled for completion by April 17,1998 (Train B had already been tested).
Also certain Unit 2 contacts that perform a load shed function and other Unit 2 contacts that ensure that non emergency diesel generator trips do not trip a diesel generator operating in the emergency mode, would be tested at power by April 16,1998. By letter dated April 23,1998, J
(TXX-98120) the licensee confirmed that the Unit 1 and Unit 2 testing was successfully I
completed by the dates indicated.
I
2.0 BACKGROUND
i During the process of performing reviews in accordance with NRC Genene Letter 96-01 " Testing of Safety Related Logic Circuits," the licensee discovered that certain lockouts, various seal-in cantacts, and diesel generator trip bypassed circuits were not verified to perform their required functions or ware not verified unambiguously using the past testing methodology. Thus, complete testing in accordance with TS Surveillance Requirement 4.8.1.1.2f had not been performed. These omissions in the surveillance testing program at CPSES have been present since the issuance of the initial operating license for Unit 2 and were identified on March 24, 1998.
i j
9805190240 980508 PDR ADOCK 05000445 l
P PDR i
. The licensee requested proposed TS change does not impact the improved Technical Specifications (ITS) because it is a temporary one time change and is plant specific. In addition, the proposed change does not impact the ITS submittal for CPSES. Prior adoption of approved line-item improvements to the TSs or the iTS would not have obviated the need for the license amendment request.
3.0 DISCUSSION AND EVALUATION The safety basis for the licensee amendment request is in accordance with the safety functions and significance of the components that have not been fully tested per the appiicable TS SRs.
The safety functions and significance of these components are as indicated in the attached Tables 1,2 and 3. The following paragraphs address the classifications and categories denoted on the tables.
Item numbers 2, 3,4, 5, and 6 on the attached Table 1 list automatic and some operator lockcas that block undesired automatic actions, that start and stop equipment, that actuate auxiliary relays, and which require testing, item numbers 1,3, and 5 on the attached Table 1 list lockouts that block undesired manual actions and which reMe testing. The attached Table 4 identifies the affected equipment for the first five items !ist% sn Table 1. A review performed by the licensee for the lockouts listed on Table 1 did not reveal a method of testing them in totality during plant power operations without exposing Unit 2 to undue risk. However, the licensee demonstrated the functionality of the relays which actuate the contacts indicated on Table 1.
Each of these relays was shown to have actuated by a positive verification methodology. This methodology included exercising the relay coils. While the relays were safely exercised during plant power operations, due to the setup required to actuate, monitor, and verify all individual contacts, the licensee was not prepared to state these actions could be performed safely at power. In addition, relay contacts involved with Train A common buses are denoted by item 7 on i
Table 1. The Unit 2 relay contacts that effect these buses are Category 3 and are included in the first six items on Table 1. The Unit 1 relays were tested during the Unit i sixth refueling outage and as such are noted on Table 1 as Category 5.
The safety functions of the lockouts are indicated on Table 1 by groupings. The lockout relay contacts are to ensure that perturbations in the emergency diesel generator (EDC) starting and loading sequence are avo;ded. Failure of the lockouts that block automatic and manual actions would allow loads to attach or be attached inappropriately to the EDG bus potentially rendering it unavailable as the power source for the necessary equipment to support obtaining or m:intaining sa's shutdown following an event. Failure of the lockouts that start and/or stop equipment could i
result in equipment not being available as assumed in the plant accident analysis or could result in an excessiva load on the EDG at some point during its loading sequence.
In addition to performing relay functionality verifications and to further support operability of ity CPSES Unst 2 lockout relays and attendant contacts of concem, the licensee provided the followmg additional' formation.
m 1.
The lockout relays in question are identical to the load block relays that have routinely been tested over the life of CPSES Units 1 and 2. During the course of more than eight years of operation and testing, none of these relays have failed to perform their function.
1
i 3
2.
The CPSES Unit i lockout relays and contacts, which are essentially identical to the lockout relays for Unit 2, were tested during the recent Unit i refueling outage. As the licensee expected, no failurer were identified and this surveillance testing served as confirmation of operability.
3.
Pre-operational testing in 1992 verified that the relays and contacts of concem operated as designed. Thus, when the relays actuate by positive verifications, reasonable assurance exists that the contacts reposition correctly.
)
4.
The sequencer relay coils are continuously monitored on-line for continuity. If continuity is lost, the sequencer trouble alarm would alert the operators.
5.
The CPSES EDGs have repeatedly demonstrated the capability to start ar:d load satisfactorily without problems introduced by or malfunctions of either the lockout relays or
{
their attendant contacts. These previous tests provide additional evidence that the confirmation of operability is highly probable. Although this testing has not pcovided I
unambiguous confirmation that the relay contacts perform their function, it is most likely that the circuits have responded appropriately during the past integrated tests.
6.
The manual actions that the lockouts are designed to block are very unlikely to occur. The period of time in which these blocks are essential is about 110 seconds or less, in addition, both the operating procedures and operator training include aspects which decrease the chances that the undesirable manual actions would occur.
Item numbers 1 and 2 on the attached Table 2 list those seal-in contacts for CPSES Unit 2 that perform a load shed function consistent with licensing basis requirements and which have not previously been unambiguously tested. Item number 3 on the attached Table 2 lists the contacts for Unit 2 that perform a load shed function for the instrument air compressors. The licensee's review for these three items determined that the associated relay contacts may be safely tested during plant power operations and as such are denoted on Table 2 as Category 2. Item number 4 on the attached Table 2 lists the seal-in contacts for the Train A common buses. These relay contacts are Category 5 for these common buses since they were transferred to Unit 1 and tested during the recent Unit i refueling outage.
The safety function of the seal-in relay contacts is to ensure the associated equipment does not load inappropriately onto an emergency bus powered by an operating EDG. The safety function l
of the load shed relay contacts is to ensure the instrument air compressors are shed from an emergency bus prior to it being powered by an EDG. For these cases, the attendant relay contacts are provided to ensure that unnecessary electrical loads do not cause perturbations in i
the EDG staiting and loadiag sequence. Failure of equipment attendant seal-in and/or load shed relay contacts in a munner as to allow electrical loading to attach inappropriately to an emergency bus could render it unavailable as the power source for the necessary equipment to
. support obtaining and/or maintaining safe shutdown i
j r
. following an event. However, individual equipment items associated wi h the seal-in and load shed relay contacts are relatively small in comparison to the allowable liDG capacity and capability. Thus, based on a qualitative assessment, a combination of1ailures would be necessary to render the EDG incapable of performing its function.
j Table 3 lists relay contacts for CPSES Unit 2 that perform the function of ensuring that non emergency trips do not result in the trip of an EDG operating in the emergency mode. The licensee's review for these relay contacts determined that they may be safety tested during plant power operation and as such are denoted on Table 3 as Category 2. The safety function of these relay contacts is to ensure that engine overspeed and generator differential are the only trips that result in tripping an EDG operating in the emergency mode. Failure of these relay contacts could result in an EDG tripping on a non emergency trip signal when it is operating in the emergency mode. For the worst case scenario involving these relay contacts, the EDG would trip from a valid non-omergency trip signal. However, the emergency response guidelines contain operator recovery instructions for this scenario.
To perform the relay functionality verifications (Table 1 Items) and the segmented relay testing (Tables 2 and 3 ltems) during plant power operations, the licensee used operating and testing procedure:: designed to minimize adverse impacts on plant safety. As part of the procedure development, the licensee considered conditions required to perform the functional verifications and segmented testing activities and the resulting actions to occur when these activities are performed. When relay contacts operated, there were cases where the equipment did not either need to operate or should not be operating. If the equipmant did not need to operate, the procedures required an operator to shut that equipment down. If the equipment should not be operating, the procedures included actions to inhibit its operation. The potential impact was also minimized by performing functional verifications and testing activities only on one train of equipment at a time. When these activities were completed, the procedures include restoration actions to retum the equipment to its normal operating condition. As previously indicated in this report, the relay functionality verifications and segmented testing for the items listed in Tables 1, 2, and 3 were successfully completed as of April 17,1998.
To further support the TS change request, the licensee perfo(med a plant specific evaluation to estimate the potential impact of the deferral of the CPSES Unit 2 TS required testing on overall plant risk. This evaluation was performed using the CPSES Individual Plant Examination model.
The results for this evaluation indicate that the total core damage frequency (CDF) could increase by less than 2 percent should the required testing be deferred to the next Unit 2 refueling outage. This increase in CDF is viewed to be insignificant.
As an administrative matter, it is noted that none of the items listed on Tables 1, 2, or 3 were assigned to Category 1 or Catsgory 4. As indicated on the tables, Category 1 is for items that are not required to be tested. Since suct items are not required to be tested, they are not within the scope of the licensee amendment request and do not need to be identified or listed. A Category 4 is also indicated in the tables but no items were assigned to this category. This category was initially created by the licensee as one in which some of the untested components might best be assigned. However, based on additional reviews performed and actions taken by the licensee, none of the untested components were assigned to this category and as such it was not addressed further.
t
. 4.0 EVALUATION CONCLUSIONS On the bases of the information contained in the above evaluation, the staff concludes that there
'is reasonable assurance that the as discussed CPSES Unit 2 lockouts, seal-ins, and EDG trip
(
bypass relays and attendant contacts are operable and if necessary will respond in a manner consistent with design and licent.ing basis requirements. In addition, the staff concludes that the temporary one time TS change for SRs 4.8.1.1.2f.4) and 4.8.1.1.2f.6) to add the footnnte, "On a one time basis, the verification of the proper operation of the Unit 2 load shed seal-in contacts and the diesel generator trip bypass contacts may be performed at power, and the verification of the proper operation of the Unit 2 lockout relays and contacts may be deferried until the startup from 2RF04 or earlier outage to at least MODE 3,"is acceptable, j
5.0 EXIGENT CIRCUMSTANCES
l As described in Section 2.0 above, the amendment request was the result of reviewing
)
surveillance procedures in accordance with NRC Generic Letter 96-01. In this case, the 1
licensee took prompt action to remedy the. situation, and entered TS 4,0.3 (which could havo led to the shutdown of CPSES Unit 2 if the action requirements were not met within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />),
evaluated the safety significance of the situation, and requested an NOED. The amendment request was submitted in a timely manner after the NOED was granted.
4 The Commission's regulations in 10 CFR 50.91 contain provisions for issuance of an amendment
' where the Commission finds that exigent circumstances exist, in that a licensee and the Commission raust act quickly and that the time does not permit the Commission to publish a FederaIRegisternotice allowing 30 days for prior public comment The exigency exists in this i
case in that the proposed amendment was the result of an NOED granted to prevent the shutdown of CPSES Unit 2. The staff has detennined that the licensee used its best efforts to make timely appli_ cations associated with the NOED Accordingly, the Commission has
{
determined that exigent circumstances exist pursuant to 10 CFR 50.g1(a)(6) and cou'd not have been avoided, that the submittal of information was timely, and that the licensee did not create the exigent cendit!on.
6.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION
S DETERMINATIQB t
The Commicsion's regulations in 10 CFR 60.g2(c) state that the Commission may make a final determination that a license amendment involves no significant hazards consideration if operation of the facility in accordance with the proposed amendment would not (1) involve a significant increase in the probability or consequences of an accident previously evaluated, (2) create the possibility of a new or diffarent kind of accident from any accident previously evaluated, or (3) result in a significant reduction in the margin of safety. The NRC staf' has made a final determination that no significant hazards consideration is involved for the proposed amendrmmt and that the amendment should be issued as allowed by the criteria contained in 10 CFR 50.gi. The NRC staffs final determinations are presented below.
- 1. The change does not involve a.significarit increase in the probability or consequences of an accid-t previously evaluated.
The proposed change is to de' lay the performance of ce tain portions of the surveillame
[,
testing of specific devices and for the crediting of the at power testing of certain portions of
I i
l
\\
+
l shutdown surveillance requirements as previously described and listed in Tablos 1,2, and 3.
Delaying performance of these tests until such time as approprinte or credWing of at power l
testing of shutdown surveillance requirements does not increase the probability of an accident; therefore the probability of an accident previously evaluated is not increased.
No plant equipment is adversely affected by not performing these aurveillance tests. The consequences of an accident, as analyzed in the FSAR, does not increase from not having performed the testing. Based on the statements above and the expectation that the deferred
{
testing and the at power testing will confirm OPERABILITY, this change poses no increase in j
the consequences of a previously evaluated accident.
i l
2 The change does not create the possibility of a new or dif forent kind of accident froin any I
accident previously evaluated.
I Delaying the performance of tests and the crediting of at power testing of shutdown surveillance requirements are administrative actions and do not have the potential to create a new or different kind of accident from any previously eyaluated. The s:ystems will continue to respond in the same manner as they currently do.
1
- 3. The change does not involve a significant reduction in the margin of safety.
Delaying the performance of, or crediting the at power testing of shutdown surveillance requirements for those portions of the surveillance testing necessary to demonstrate the lockouts and seal-in circuitry, does not significantly mduce a margin of safety. The circuitry is expected to perform its design functions.
j 7.0 SI6TE.fC)NSULTATION In accordance with the Comtnission's regulations, the Texas State officialwas notified of the proposed issuance of the amendments. The State official had no comments.
l
8.0 ENVIRONMENTAL CONSIDERATION
1 The amendments change a requirement with respect to installation or use of a facility component l
located within the restricted area as defined in 10 CFR P. art 20. The NRC staff has determined that the amendments invnive no significant increasa in the amounts, and no significant change in the types, of any effluents that may be released off site, and that thare is no signifi: ant increase in j
bndividual or cumulative occupational radiation exposure. The Commission has previoush issued A proposed finding that the araendments involve n a significant haznrds conskharation, and there has been no public comment on such finding (63 FR 13534). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set f orth in 10 CFR 51.22(c)(9). Pursuant to i
10 CFR 51.22(b) no tanvircnmental impact staterr ent or environmental a,ssessment need be prepared in corinection with the issuance of the tmradments.
9.0 CONC; USION The Com6sion hos concluded, based on the considerations discust,ed above, that: (1) there is reasonabic cscurence that the health and safety of the public will not be endangerad by l
. operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regJiations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Attachments: 1) Table 1
- 2) Table 2
- 3) Table 3
- 4) Table 4 i
Principt.i Contributor. F. Ashe Date: May 8, 1998 1
a i
0 l
TABLE 1 LOCKOUT CONTACTS EQUIRING TESTING R
Item at tn Classification Train Affected Equipment g
)
5 1
A and B 61 l ',
No See Table 4 a uaI sta s I
2 A and B 23 3
No See Table 4 i s 3
,'nd A and B 24 3
No See fable 4 to stads Lockout - Starts and/or 4
A and B 17 3
No See Table 4 stops equipment
- ,fy fy uates an 5
A and B 12 3
No See iterns 1,2, 3 and 4 Automatic Lockout -
i
)
6 Bypass / block OG A and B 4
3 No DG Output Breaker j
interiock/ trip Loc 6 out - Functions in
'7 common circuits and Unit 1 Train A and B A and B 54 5
NA will be tested by Unit 1 lockout relays L
testing during 1RFO6 (1) Number reflects the number of contacts (2) Category 1 -Testing is not required Category 2 -Testing may be performed at power Category 3 -Testing not to be performed at power, however relay functionality either has been demonstrated or will be demonstrated prior to the end of the current enforcement discretion.
a Category 4 - Not used Category 5 - Testing to be performed during 1RFO6 i
ATTACHMENT 1
TABLE 2 SEAL-IN CONTACTS REQUIRING TESTING N*'"
t n
Classification Train Affected Equipment
)
DG Jacket. Water Heater RHR Room Fan Cooler Containment Spray Pump l
Room Fan Coolers St Pump Room Fan l
Load Shed - NOT Cooler l
1 Verified during Normal A
10 2
Yes Motor Drive AFW Pump l
Operations Room Fan Cooler CCW Pump Room Fan Cooler Positive Displacement Charging Pump Room Fan Cooler DG Generator Space Htr DG Lube Oil Heater DG Jacket Water Heater RHR Room Fan Cooler Containment Spray Pump m an Golers Load Shed - NOT S P mp Room Fan 2
Verified during Normal B
9 2
Yes Operations Motor Drive AFW Pump Room Fan Coo!er CCW Pump Room Fan Cooler DG Generator Space Hir Load Shed - NOT Instrument Air 3
Verified during Normal A and B 2
2 Yes Operations Compressors Control Rcom AC Units Load Shed - NOT Vent Filter Heaters 4
Verified during Normal A
9 5
NA Ventilation Fans Operations Spent Fuel Pool Pumps (1) Number refiede the number of contacts (2) Category 1 -Testing is not required Category 2 -Testing may be performed at power Category 3 -Testing not to be performed at power, however relay functionality either has been~
demonstrated or will be demonstrated prior to the end of the carrent enforcement l
discretion.
}
Categoiy 4 - Not used Category 5 - Testing to be performed during 1RFO6 ATTACHMENT 2 i
I TABLE 3 VARIOUS CONTACTC REQUIRING TESTING N',*
- '{1 Affected Equipment Classification Train
)
D Nomemegency inps for i
DG Trip Bypass A and B B
2 Yes the EDG (1) Number reflects the number of contr. cts (2) Category 1 -Testing is not required Category 2 -Testing may be performed at power Category 3 -Testing not to be performed at power, however relay functionality either has been demonstrated or will be demonstrated prior to the end of the current enforcement discretion.
Category 4 - Not used Category 5 - Testing to be performed during 1RFO6
)
s
?
ATTACHMENT 3 1
TABLE 4 Lockout Relay Functions Loads with a block of automatic or manual start:
Chilled Water Recirc Pumps CCW Pumps AFW Pumps SSW Pumps Pressurizer Heaters Vent Chiller Water Recirculation Pump Spent Fuel Pool Cooling Pumps J
Control Room AC Units i
Reactor Makeup Water Pumps DG Air Compressors UPS HVAC Unit Fans Safety Chillers DG Jacket Water Pumps DG Aux Lube Oil Pumps DG Prelube Pumps Instrument Air Compressors Containment Spray Pumps St Pumps RHR Pumps CCP Pumps Containment Recirc Fans Chilled Water Recirc Pumps PD Pump Aux Bldg Equip Rm Exh Fons Plant Vent Exh Fans Loads with an automatic start anolor fjtoJ:
TDAFW Pump Vent Chilled Water Pumpa Rad Monitors DG Emergency Start Spent Fuel Pool Pumps Safety Chillers Reactor Makeup Water (80mps b
ATTACHMENT 4
-