ML041320358

V. C. Summer April 2004 Exam 50-395/2004-301 Post-Exam Comments

ML041320358
Person / Time
Site:	Summer
Issue date:	04/28/2004
From:	Byrne S South Carolina Electric & Gas Co
To:	Reyes L Region 2 Administrator
References
Download: ML041320358 (19)

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Pos t-exa m i nation C o m men ts V. C. SUMMER EXAM 5Q-395/2Q04-3Ql APRIL 19 p 23,2004 April 28, 2004 (written)

0 A SCANA COMPAMY Stephen A. Byrne Senior Vice President, Nuclear Operations 803.345.4622 May 5,2504 Mr. L. A. Reyes Regional Administrator, Region I1 U. S. Nuclear Regulatory Commission Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23885 Atlanta, GA 30303-8931

Subject:

VIRGIL C. SUMMER NUCLEAR STATEON DOCKET NO. 50/395 POST EXAM COMMENTS FOR THE RO EXAM ADMINISTERED APRIL 28,2004 OPERATING LICENSE NO. NPF-12 Please find attached SCE&G's post exam comments for the RO exam admlnistered at V. C.

Summer Nuclear Station on April 28,2004. Comments are b h g submitted for questions 1 1, 65, and 38 of the written examination. SCEBG appreciates the opportunity to provide these comments and the NRC's consideration of the information.

If you would like to discuss this information in more detail, please contact Mr. Rusty Quick of my staff at 803-931-5091.

Very truly yours, Stephen A. Byrne CJMISABIcm Attachments c:

M. E. Ernstes R..§. Baldwin NRC Resident Inspector File (814.64)

A. R. KoOn WTS (b-99-0251)

DMS (RC-64-0083)

SCE(EG I Vlrgil C, Summer Ho:leor Station P. 0. Box 88.lentmrville, South (oralino 29065.T (803) 345.5209 =ww.scnno.cnm

Question t# 11 :

1 1. 01 1A3.03 I

-The Unit is at 100% power

-Pressurizer level channel selector switch is in the 468/46B position

-The sensing line to pressurizer transmitter 460 develops a reference leg leak near the connection point to the DiP cell.

Which one of the following correctly describes the expected plant response? (assume no operator action)

A. LT-460 indication will fall, charging flow will rise, actual pressurizer level will rise, LCV 460 will isolate letdown.

B. LT-460 indication will rise, charging flow will fall, actual pressurizer level will fall, pressurizer deviation alarm will corn in.

C. LT-460 idcation will fall, charging flow will rs'se, actual pressurizer level will fall, LCV 461 will isolate letdown.

D. LT-460 indication will rise, chaqjng flow will rise, actual pressurizer level will MI, pressurizer heaters will energize.

Modified bank questions Summer question 1161, and Farley bank question.

A. Incorrect, LT-468 indication will rise, chg flow will fall, actual pressurizer level will fall, and 460 will not isolate letdown.

B. Correct.

C. Incorrect, LT-460 indication will rise, chg flow will fall, actual pressurizer level will fall, but 461 could isolate letdown.

D. Incorrect, LT 460 indication will rise, chg flow will lower, actual pressurizer level will lower, the pressatrizer heaters will not energize.

Answer: B Proposed Action:

Change the correct answer ffom B to D

Justification:

The given conditions provide the examinee with a reference leg break somewhere downstream of the condensing pot for LT 460. The examinees with the correct understanding of how a DIP detector works, based on fundamentals, deterrnine that level would rise. Only answers B and D provide that option.

Considering charging flow control valve FCV 122 and how it will respond, charging flow wntrol will send a decreasing signal in response to the actual PZR level rise (LT 461), or an increasing signal in response to an actual PZR level fall. If the leak is large enough, then actual indicated charging flow will increase in respgnse to the system pressure drop as well, as the affect of decreasing system pressure is a lower backpressure or the charging pump to pump against. It is difficult to predict what would happen to charging flow based on this type theoretical approach, yet in no case will charging flow act in the same direction as PZR level change as described in answer B.

As no specific size was specified in the question, we tried two scenarios on the simulator in an attempt to estimate what we thought might be seen with a reference leg leak on a level detector downstream of the condensing pot.

For a very small steam space leak (we used 10 GPM), actual PZR level fell, as well as charging flow increasing in response to the leak. It was clear that there was not enough mass or pressure lost to cause any appreciable change in reference leg pressure on the controlling channel (in this case, LT 461), and therefore indicated PZR level goes down solely in response to the mass loss. Charging flow will increase in response to the PZR level decrease, and will continue to rise until charging flow matches and then exceeds break flow, and PZR level returns to program This would suppofl m e r D.

We also ran the steam space leak at 75 GPM. Likewise, the leak was not large enough to cause a flash or large decrease in reference leg pressure for the controlling channel D/P level detector, so the indicated PZR level fell continuously, and charging flow rose continuously, until the RCS pressure decreased to the SI set point and a Rx. Trip/ SI occurred. This size leak also supports answer D Additionally, PZR backup heaters will energize as RCS pressure lowem to below 2210 PSIG.

Answer B is incorrect, regardless of whether or not the examinee considered this as s BZR steam space LOCA, where charging flow and actual PZR level would botb rise, or if they took the m r e conservative approach with a smaller leak rate and determined that charging flow would increase, while actual pressurizer level decreased. Answer B cannot be correct, as charging flow cannot fail in response to an actual pressurizer level fall, no matter what circunsstances the examinee considered.

10 GPM Pzr Steam Space Leak 59.85 59.8 59.75 59.7 59.65 -

E.

3 2

59.8 2 1

59.55

' 59.5

- 59.45

- 59.4

- 59.35 10 30 50 70 90 110 130 150

-1 0 Time (Seconds)

75 GFM Pzr Steam Space Leak Pzs Level (LT-461) lt:461 40 60 80 100 120 140 160 0

20 Time (Seconds)

10 GPM Pzr Steam Space Leak

. 59.a

. 59.8

' 59.75 59.7 59.65 59.6 59.55 59.5 59.45 59.4 59.35

-10 10 30 50 70 90 I f 0 130 150 Time (Seconds)

Associated with each circuit breaker control switch are three breaker status lights:

green, amber, and red. Amber indication means that the control switch has been operated to close the associated breaker (Le., taken to CLOSE and allowed to spring-return to the midposition) and that the breaker has tripped open for some reason other than the switch's being taken to TRIP. Both back-up heater groups aiso have individual control transfer switches (REMOTE, LOCAL) and local control switches (STOP, START) at the evacuation panels. The transfer switch maintains the position selected; the local control switch spring-returns to the midposition.

The control features for both back-up heater group supply breakers are identical.

Normally the transfer^ switch at the CREP, which is a two-position selector switch, is in REMOTE. This transfers circuit breaker controi to the switch on the MCB (the remote control switch), which is normally in the midposition. The rnidposition aligns the switch contacts in one of two ways, AFTER TRIP ot AFTER CLQSE, depending upon the last breaker position selected. AFTER TRIP means that the switch is in the midposition after having spring-returned from the TRIP position. AFTER CLOSE means #at the switch is in the rnidposition after having spring-returned frurn the CLOSE position.

The back-up heater group breaker closes under the following conditions:

e Transfer switch in REMOTE and any one of the following:

- Remote control switch to CLOSE

- Pressure deviation-tow-25 psi from setpoint, (P5M44F)

- Level deviation-high +5 percent of span from setpoint (LB-459B) e Transfer switch in LOCAL and local control switch to START

Question # 15

15. 014K3.02 1

-The Unit is operating at 100% power.

-Annunciator XCP-620(2-5) CMPTR ROD DEV illuminates.

Which ONE of the following is a condition that could cause the above alarm?

A. A Bank step counter malfunction has occurred.

B. A flux tilt of greater than 2%.

C. An error or failure from both DRPI data cabinets.

D. An IPCS computer failure.

Used Summer Bank Question 2122 for idea.

Summer Objective I C 4 1 6,and 17.

A. Incorrect, this would cause a CMPTR ROD SEQ alarm.

B. Incorrect, this would not cause the above alarm.

C. Incorrect, this would cause a DRPH Alarm Urgent failure.

D. Correct, if the IPCS computer hiled this alann would come in.

Answer: D Proposed Action:

Accept either choice C or D

Justification:

Answer D is taken directly from the list of probably causes outlined in the Annunciator Response Procedure for XCP 620 2-5 "CMPTR ROD DEV."

Refer to the attached Figure 2-3 from the Westinghouse DRPI technical manual. The DRPI cabinets receive a sigml from each individual rod as to it's position. The signal is then sent to the control board display 110 c'ard, which is in turn sent to the piant computer (IPCS) I/O card and compared to expected rod position based on demand. If a discrepancy exists at >I2 steps, computer point Y2001C generates an alarm on XCP 620, window 2-5, CMPTR ROD DEV. The ARP lists IPCS computer Pdilure (answer D) as a probable cause, along with three other possibilities.

However this is not an all-inclusive fist of malfunctions that could cause a computer rod deviation. In discussing the distracters with Rod Stem, a fomier Westinghouse rod control system engineer and current I&C supervisor at VC Summer, about how DRPI and the IPCS interfaced, Rod indicated there were numerous ways that both DRPI data cabinets could either fail or create an error, as indicated in answer C, thereby causing a computer rod deviation alarm to be generated by the IPCS plant computer.

E ' -

Fig. 2.3

COWVIER INPUT/OUTPUP CARD (Refer t o Figures 2.92, 2.93 and 2.94)

The Computer I/O card is used t o interface the DRPI system w i t h any process computer t h a t has contact closure i n p u t s and outputs.

Since t h d s method of interface is slow, the DRPI system must be synchronized w i t h, but not slaved to, the computer.

Therefore, a memory is provided on the card t o contain all infomation concerning rod positlon which can be interrogated by the computer a t its own speed.

The infomation i s continuously updated and can be 0

interrogated by the computer at any time (Figure 2.92).

0 To keep the computer input independent of the Display Card's visual presentation, the Computer I/O card receives the positlon data from the Display I/O cards.

T h i s includes the A Data, the B Data, the Parity Error A,

and the Parity'Error B.

The Computer I/O card generates a computer interrupt sfgnal each time a data change is detected between two consecutive address cycles.

S3B and S4 outputs from the Central Control Cards are provided to the Computer I/O card's timing cdnuitry.

period i n t o three parts.

period, the Central Control Cards control the Computer I/O card i n order t o determine change i n data and t o update infomation i n memory.

one quarter o f each address period, control of the card is given t o the computer t o interrogate any rod address.

Burin9 the f i r s t one h a l f of each address period. the new data for the addressed rod i s stored f n the i n p u t latch memories.

Sdmultaneausly, the oid data for t h a t address i s read from the random access memordes (RAM'S) and applied to a latch memory for future comparison.

the i n p u t latch memory is wrdtten into the RAFl's.

to a comparator, along w i t h the old data for the same rod.

detects a change i n the new data for the same rod.

a change i n the new data, a computer interrupt signal will be generated.

During the fourth quarter of each address period, the computer may address the RAM'S.

This timing circuitry divides each address Quring the first three quarters of each address During the l a s t During the t h i r d quarter of the address period, the new data in This data i s also applied If the comparator If the Comparator detects e

The data correspondSng t o the computer address i s read from the RAM'S and applied t o a latch memory.

t o the computer.

The output of this latch memory i s available e

2-1 44 8115S:4

The DWI address i s supplied to the computer I/O sard in order to store data i n appropriate RPM's.

allow the computer to selectively retrieve data.

The computer address i s of similar format and will 0

2-1 45 011 5§:4

ARP-001 REVISION 8 PANEL XCP-620 ANNUNCIATOR POINT 2-5 SETPOINT:

ORIGIN:

CMPTR Rod > 12 steps from bank demand Y2001 c Rod > 12 steps from reliable average bank position u

PROBABLE CAUSE:

1.

2.

Dropped control rod.

3.

IpCS Computer failure.

4.

Rod Supervision Program halted.

Stuck or misaligned control rod.

AUTOMATIC ACTIONS:

1.

None.

CORRECTIVE ACTIONS:

I.

2.

Observe the Digital Rod Position Indication display for proper rod positions.

Determine if the cause is a dropped or misaligned rod.

SUPPLEMENTAL ACTIONS:

1.

2.

3.

4.

5.

6.

If a rod is misaligned, refer to AOP-403.5, Stuck or Misaligned Rod.

If a rod is dropped, refer to AOQ-403.6, Dropped Control Red.

Operate the Rod Control System in MAN as described in SOP-403 until proper automatic Rod Control in restored.

Refer to Technical Specification 3.2 3.1.

If the IPCS Computer failed, refer to CMPTR SPCS FAIL (XCP-632 6-5).

If the cause of the aiarm has not been determined, perform the following:

a.

At an IPCS terminal, enter GRPDIS or depress the GRPDlS key.

b.

Enter the group name TASK-MON.

C.

Enter a screen update rate.

d.

Verify Y9622, Rod Supervision Calc, is RUNNING.

e.

If Y9622 is HALTED, perform the following:

1 ) Contact Nuclear Computer Services.

2)

When the alarm dears, verify Y9622 is RUNNING.

if the alarm is inoperable, perform GTP-782, Attachment iV.B, h0peFable Rod Position Deviation Monitor.

7.

PAGE 15 OF 34

ARP-001 REVISION 8 PANEL XCP-620 ANNUNCIATOR POINT 2-5 (Continued)

REFERENCES:

1.

2.

3.

4.

5.

6.

7.

8.

8-804-620, Sh. 2.

B-208-074, NI-53.

SOP-403.

AOP-403.5.

V.C. Summer Technical Specifications.

IPCS Documentation.

GTP-702.

AOP-403.6.

PAGE 16 OF 34

Question # 38:

38. 057AG2.1.32 1

-The Plant is at 100% power during an A1 maintenance week.

-APN-5301 has been transferred to APN-1FA while work is in progress on XIT-5901.

-The Normal feeder breaker for APN-1FA trips open due to a fault.

Which ONE of the following describes the effect that this will have on the ESFLS system?

A. "A" Train loads will be shed and an ESFLS will be initiated.

B. "B" Train loads will be shed and an ESFLS will be initiated.

C. "A" Train loads will remain connected and ESFLS will be disabled.

D. "B" Train loads will remain connected and ESFLS will be disabled.

Modified from Summer Bank questions 2032, and 4305.

Objective # GS-2-20.

A. Incorrect, this is the correct train, however the loads will not be shed and ESFLS will not be initiated.

B. Incorrect, this is not the correct train, and the loads will not be shed and ESFLS will not be initiated.

C. Correct, this is the correct train and the loads will not shed and ESFLS will be disabled.

D. Incorrect, this is the wrong train.

Answer: C Proposed Action:

Accept either choice C. or D.

Justification:

The given conditions have inverter XIT-5901 undergoing maintenance; therefore, APN-5901 is being powered from APN-1FA. The question stipulates that the feeder breaker to APN-IFA then trips, de-energizing APN-IFA.

Since an undervoltage condition on the vital busses, IDA or IDB is not stipulated, the ESFLS on Train B will not be actuated. For the same reason, neither A Train nor E3 Train running equipment will be affected. This makes the first part of Choices C. & D. correct.

With APN-IFA supplying APN-5901, power to the A Train ESFLS is lost when the normal feeder breaker to APN-IFA trips. Since the second part of Choices C. & D. does not specify which Train of ESFLS is disabled, the second part would be correct since A Train is disabled. Said another way, the second part of Choice D. would only be incorrect if it referred specifically to B Train ESFLS.

VITAL 120VAC AND 125DC

SOP-310 REVISION 9 M. REMOVAL OF iNVERTER XiT5901 FROM SERVICE Continuous Use of Procedure Required.

1.O INITIAL CONDITIONS 1.1 1.2 APN5901, f20V VITAL AC DlSTR PANEL I NSSS, must remain energized.

APNIFA, 120 VOLT AC lNST MAIN DlSTR PANEL 1 FA. is energized.

1.3 1.4 AQN-IFA-EM 19, ALT SOURCE FOR APN5901 VIA XIT5901. is closed.

OR XiT5901,120 VOLT VITAL AC IOKVA UPS, the ALT AC SOURCE Breaker is closed.

The MAN. BYPASS Switch is in the NORMAL position.

The TEST TRANSFER Switch is in the center position.

1.5 1.6 Placing APN5901,12OV VLTAL AC DlSTR PANEL 1-NSSS, on ALT SQURCE from APNIFA, 120 VOLT AC INST MAIN DISPR PANEL lFA, will prevent Train A Engineered Safety Features Load Sequencer from operating during a Blackout 2.0 INSTRUCTIONS 2.1 2.2 2.3 Verify the following:

Verify that the SYNC MONITOR Light is not lit.

Place the TEST TRANSFER Switch to the ALT position.

a.

b.

The ON ALTERNATE Light illuminates.

The ON INVERTER Light goes out.

PAGE21 OF58