ML19344E473

Responds to IE Bulletin 80-17,re Failure of Control Rods to Insert During Scram.Forwards Special Test Procedure 80-9 Sequence of Events Indicating That All Equipment Performed as Designed & No Corrective Action Necessary

ML19344E473
Person / Time
Site:	Cooper
Issue date:	07/30/1980
From:	Pilant J NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
IEB-80-17, NUDOCS 8009020101
Download: ML19344E473 (5)

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. - - - ._ i July 30, 1980 Mr. Karl V. Seyfrit, Director U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Subject:

IE Bulletin No. 80-17 Failure of 76 of 185 Control Rods to Fully Insert During a Scram at a BWR

Reference:

Telecopy dated July 14, 1980, L. C. Lessor to Glen Madsen, same subject (copy attached)

Dear Mr. Seyfrit:

The subject bulletin described an event which raised concern regarding operation related to the control rod drive (CRD) system scram discharge volume (SDV). The bulletin required that certain tests be performed within twenty days (which started July 8,1980) and a report submitted in regards to the results of these tests within five days after com-pletion of the tests (tests completed July 26, 1980). The following items correspond to the tests specified in Section 2 of the subject bulletin. These tests were performed at normal operating temperature and pressure with more than 50% of the rods fully withdrawn,

a. All rods inserted within 3.43 seconds on the manual scram. We did not obtain the "all roua" inserted time on the automatic scram due l to a problem with a rod position indication system (RPIS) logic l card on control rod 26-23. Control rod 26-23 was at position 00 l (fully inserted) prior to the automatic scram. After the automatic 1

scram, it was still at position 00 (as verified with the process computer), but it indicated both full-in and position 05 on the control room RPIS panel. After the problem was corrected, control rod 26-23 correctly indicated position 00 and the "all rods" in-serted signal was received by the process computer.

b. Scram solenoid valve buses de-energized 0.017 seconds after receipt of the scram signals.

8 0 0902 0 I<gt

Mr. Karl V. Seyfrit July 30, 1980 Page 2.

c. Scram valve air is relieved through the backup scram valves; the backup scram valves received an open signal 0.05 seconds af ter both scrams. The backup scram valves remained open until the scram signals were reset,

d. See attached sequence of events table for fill times of the in-strument volume after scram initiation.

e. The SDV volume vent and drain valves were determined to open and close within 2.5 seconds following a scram or scram reset signal.

This was determined prior to the execution of the tuo scrams.

f. See attached sequence of events table for delay time from scram initiation to closure of the SDV vent and drain valves.

g. Water samples were obtained from the SDV following both scrams.

The results indicated no abnormal particulates existed in the samples.

h. The maximum drain time of the scram discharge headers was deter-mined to be approximately 8 minutes (for the north header). The south scram discharge header drained in 5 minutes. The drain time of the SDV was determined to be approximately 10 minutes (see attached sequence of events table). This was the time until no discernible level increase was noted in the reactor building equip-ment drain sump to which the SDV drains.

1. An air flow test was performed following each scram; no residual water was found in the SDV and associated piping.

j. The ten (10) second delay on scram reset was found to be func-l tioning correctly (actual time was approximately 12 seconds).

r i k. The two data sets agreed very closely and no anomalous results were

! noted.

Additionally, the SDV pressure was monitored during the two scrams.

Pressure reached approximately 125 psig during the manual scram and approximately 810 psig during the automatic scram. The difference is

! attributed to the different lengths of time until the scram was reset

! for the two scrams. The manual scrs= was reset after approximately 1 l minute while the automatic scram was reset after approximately 3.5 minutes. As a result, the pressure in the SDV reached a higher value on the automatic scram.

i l

l

. Mr. Karl V. Styfrit

' July 30,1980 Page 3.

After the scrams, the SDV vent lines were verified to be functional and it was determined that no significant amount of water was present in the SDV and associated piping (see item 1. above) .

Af ter the results of the above tests were reviewed, it was judged that all equipment performed as designed and that no corrective actions were necessary. M

}

The setup and performance of these tests took approximately 3.5 man- ,

months. /

/

/

A copy of the reference telecopy is attached for documentation ~)u'rposes.

General Electric review of the procedures discussed in Action Item 4 is completed.

Sincerely, a ," Pilant Director of Licensing and Quality Assurance JMP: ROP:ck At tachments cc: U.S. Nuclear Regulatory Commission Office of Inspection & Enforcement Division of Reactor Operations Inspection Washington, DC 20555 i

i l

Mr. Karl V. Seyfrit July 30, 1980 Page 4 STATE OF NEBRASKA )

) ss '

PLATTE COUNTY )

Jay M. Pilant, being first duly sworn, deposes and says that he is an authorized representative of the Nebraska Public Power District, a public corporatien and political subdivision of the State of Nebraska; that he is duly authorized to submit this informacion on behalf of Nebraska Public Power District; and that the statements in said application are true to the best of his knowledge and belief. ,

k May'M. F11 ant Subscribed in my presence and sworn to before me this 30 day of July, 1980.

/ NOTARY PUBLIC /

My Commission expires d. [ [kA .

MINast.seneetgemens 8dME.YN R. H0Hf000fp anyamma es,on,i4 see,

jpecial Tast Prece<'ure 30-9 Sequence of Events Manual Scram Automatic Scram Time Event Ti=e Time Event Tina

1. Reactor Scrammed 020343 06 to 120952 47 t0

2. Scram Buses Deenergized 020343 07 .017 see 120952 48 .017 see

3. Backup Scram valve open 020343 09 .05 see g

Si<nal 120952 50 .05 see

4. SDV Vent Valve 32B Close 020344 56 1.83 see 120954 37 1.83 sec

5. SDV Vent valve 32A Close 020344 58 1.87 see 120954 39 1.87 sec

6. SDV Drain valve 33 Close 020345 12 2.1 see 120954 53 2.1 sec

7. All Rods In.=erted 020346 32 3.43 sec (did not get signal)

8. SDV High Level Alarm In %020403 - 20 see %121015 - 22.6 sec

9. SDV Level Rod Block In 020417 15 34.15 see 121029 24 36.62 see

10. SDV Reactor Scram In 020441 18 58.2 see 121054 19 61.53 see

11. Reactor Scram Reset 020501 41 to 121312 41 to

12. Backup Scram Valve Close 020501 54 .22 see 121312 51 .17 see Signal

13. Scram Buses Energized 020502 15 .57 see 12131'3 10 .48 see

14. Scram Reset (Ten Second %020513 - %12 sec %121324 - s12 see Delay)

15. SDV Drain Started 022813 60 to 123214 19 to

16. SDV Level Rod Block Cleared ' 022817 21 3.35 see 123217 15 2.93 see

17. SDV High Level Alarm Cleared %022820 - 6.8 see %123219 - 4.8 sec

! 18. SDV Reactor Scram Cleared 023040 51 146.85 see 123453 47 159.47 sec

, 19. SDV Drained 023943 - 11 min 30 see 124157 - 9 =in 43 see

TELECOPY TO: Glen Madsen FROM: L. C. Lessor July 14, 1980 Mr. Karl V. Seyfrit, Director U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Subject:

IE Bulletin No. 80-17 Failure of 76 of 185 Control Rods to Fully Insert During a Scram at a BWR

Dear Mr. Seyfrit:

This letter is written to report our status on action items as required by item 8 of the subject report.

Action Item 1 A test was conducted on July 3,1980 to verify that there was no sig- '

rificant amount of water in the Scram Discharge Volume (SDV). The test conducted on that date and for six consecutive days consisted of dis-charging service air in the vent line of each of the two SDV's and verifying that the air passes through the SDV and the entire drain system. On July 9,1980, another similar test was conducted using a .

steam-het water mixture. During the second test, the temperature change was measured along the bottom of the SDV header. This verified there was no damming or accumulation of water along the header.

Action Item 2

From information received to date, it appears that the failure of all l rods to insert at BF 3 was caused by an improperly drained and vented l scram discharge volume. We believe that adequate scram discharge volume has been assured without running scram tests. However, if it is neces-sary to scram and test, a report shall be submitted within 5 days fol-I loving completion of the required scrams.

l Action Item 3

! This action item will follow scram testing and/or scrams.

l

Action Item 4 A review of emergency operating procedures has been completed by station personnel. Some minor changes have been made to our procedures. The procedures have also been telecopied te General Electric for their revicv.

All licensed operators currently performing their duties (those not on vacation) have reviewed the Browns Ferry occurrence. Other licensed operators will review the occurrence prior to assuming their duties.

Action Item 5 The scram discharge volume was monitored daily for seven days with no indication of accumulated water. A surveillance test has been developed and was to be conducted on a weekly basis. As directed by you, daily surveillance was resumed on July 15, 1980.

Action Item 6 Appropriate personnel are e pre of the requirement for prompt notifi-cation of HPCI, RCIS, S' RR/ Suppression Pool Cooling and Main Steam Bypass are not ft perable for other than surveillance tests and PM of less than 24 nours.

Normal procedures previously called for operation of one RHR pump in event the normal operating limit of 900F was exceeded. It is planned to gather suppression pool cooling data in event temperatures exceed the 90 Fnormal limit or the 1000F "af ter test" limit. It now appears appropriate to operate one RHR pump through each of two heat exchangers as a maximum in event the suppression pool water exceeds 950F. It is not desirable to operate all four RHR pumps or other ECCS pumps for suppression pool cooling.

A 50.59 review to increase SLCS flow was conducted by station personnel.

The system 's presently designed for single pump operation. It is not feasible to increase the flow without major modification. We have requested General Electric assist us in any further evaluation.

Action Item 7 We have ATWS related RPT so this action item is not applicable to Cooper Nuclear Station.