ML20069E605

Forwards Questions Arising During Review of Util Submittal Describing Proposed Water Inventory Monitoring Sys.Generic Review Incomplete Due to Apparent Reluctance on Part of Util to Supply Info.Sys Unsatisfactory

ML20069E605
Person / Time
Site:	Oconee
Issue date:	09/15/1982
From:	Richard Anderson OAK RIDGE NATIONAL LABORATORY
To:	Huang T Office of Nuclear Reactor Regulation
Shared Package
ML15238A748	List: ML20069E605
References
NUDOCS 8209240433
Download: ML20069E605 (4)

Text

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• ENCLOSURE 3

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OAK RIDGE NATIONAL LABORATORY - OPERATED BY UNION CAREIDE CORPORATION fluCLEAR DIV1110N

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                                                            .           15 September 1982                                                                     .
                    " Dr. T. Huang                                                                                                             -

Core Performance Bra'nch

• Division of Systems integration -

Office of Nuclear Reactor Regulation ' Washington. D. C. 20555 *

Dear Dr. Huang:

Enclosed are questions which have arisen during our review of the submission of Duke Power Co., describing their proposed water inventory monitoring - system. Because of other commitments and an apparent reluctance to supply sufficier}tly detailed Information until recently, our generic review of the B&W

                       ' proposal has not been completed. Because the staff has adopted the position that
                     . the hot leg monitor alone is insufficient to monitor' coolant inventory, the syste'm I~                        described in this submission is not satisfactory.                                  .
           .                                                                     Very truly yodrs.                ,
                                                                                            .<                                                                   b'
                                                                                . Richard L Anderson
                 .       RLA:rla                     .                                                      -                      >
                     . RLA:rl3 cc:           J. L Anderson

• G. N. Miller '

File-NoRC ' W o . l-

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XA Copy Has Been Sent f6 PDR 209240433 820915 MP ADOCK 05000269- . 4P -

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Reference:

' Design Proposal in Response to NUREG-0737, Sect. fl.F.2: "

I Instrumentation to Detect Inadequate Core Cooling," submitted with letter dated 25 May 1982 from William O. Parker, Jr. to Harold F. Denton .. l Some responses to this request for additional Information related to the referenced

                     . document may be satisfied by citing previously . supplied documents. Such

' references should, include: the document title, number, section and pag's number and any further clarifying, commer}ts. . , ,

l -

In Sect.1.0, the applicant recognizes that NUREG-0737 requires that the ICC . ' Instrumentation ' system must cover the full range of operation. During' a SB LOCA or loss of he'at sink, Initial Indication of sp;iroach to ICC is decre'asing subcooling

                 '         margin. After system reaches saturation, the applicant claims that loss of the RCS' coolant volding can be detected by a decrease of the level in the upper 19 ft of t

the hot leg. This position, which does not include the reactor vessel* level, has not - been accepted by the staff (SECY-81-582A). '

                                                                                                                                               ~

a

1. Is this where voiding first occurs in the system? The analysis shown in Document No. 77-1126635-00 for a 0.01 filsf2lthf-1121hf111sf61 LOCA appears to show volding in the reactor vessel before the hot leg.

2. Where are the pressure and temperature sensors located for the subcooling .

margin monitor (SMM)? , .

3. Does the SMM use temperatures sensed at more than one location, e.g.,

hot leg RTD or core exit thermocouples? a The definition of ICC in Sect.1.1 is consistent with other definitions accepted by staff.

4. On the page following Sect.1.1. 'the last line states, ' ONSET OF ICC .'

INDICATED. BY: EXCESSIVE FUEL CLAD TEMPERATURES *. Please define

• excessive temperatures". '

' S. With reference to paragraph 3 of Sect.1.2, please compare the syrnptoms.

                                      .of' an over cooling' trenslent with those of a SB LOCA transient and point i

out simliarities and differences. . , 6/ It l's stated in paragraph 3 of Sect.1.2 that the operator must 'not proceed with !CC actions until ICC is confirmed. If ICC is confirmed then according to the previous definitions, the core cladding has reached ' excessive . temperatures". Similarly, under operator action No. 4 below. Show how this . o is consistent with ~ the NUREG-0737 requirement for detection of the

• lbulapproachleul to ICC. .

                               -    7. In the last paragraph under Ooerat'or Actions Durino Acoroach to ICC under Sect.1.2, what is the ' predetermined temperature

• at which further operator i actions are required? How was this value chose' n?

     ' '-              b*           8. Similarly, under Ooerator Actions Once ICC is indicated what it the value of the 'hlgher predetermined temperature

• and how was it chosen? .'

I

      ..               c    .

9. Undsr Sset. 3.1. how much of the caro cin be uncovered before the clad.

temper'atures Indicated by the CETs begin to rise? Does this depend on the rate of uncovery? In the recent ,L2-5 test at LOFT. following the recovery from a large break LOCA. the slow uncovery of the core along with the heat up of the cladding was not sensed by the core exit thermocouples until the operators manually initiated the ECCS after the clad thermocouples , had reached almost 1100 K (1450*F). Please provide an analysis to determine if such an event could occur 16 a B&W reactor. Relevant pages from the L2-5 quick look r.eport are . attached. .

                                                                                                                      . -n    -

10. List the ' spectrum of LOCA events ...that will not proceed to core uncovery.

or ICC. *

11. Provide a representative list of non-LOCA events that proceed to saturation, but not to ICC. .

At the end of the 2nd paragraph on' the second page of Sect. 3.1.' the SMM l's stated not to provide an unambiguous indication that ICC conditions could occur.- As pointed out above. NUREG-0737 requires an unambiguous indication of 'an ,, approach'to ICC. Loss of subcooling margin is stated elsewhere to be a necessary condition for ICC. so that this would be an unambiguous Indication of approach to i ICC - necessary. but not sufficient.

12. In the third paragraph of th6 second page under Sect. 3.1. It is stated that continued Inventory loss *would lead to volds at the high points in the

                    .          system, e.g. the reactor head and the upper U of the hot leg piping.

Provide an analysis to show where the volds would first appear under an,y scenarlo that could lead to ICC. . g

13. Describe the conditions under which it is possible for volds to appear at one location and not the other. .

              ~
                    . 14. The paragraph under Sect. 3.1 beginning. "As the SB LOCA scenario                                 .

continues..... describes the use of the core exit thermocouples to monitor continued progression towards ICC. (also see comments under question 9.. l above.) -

15. Describe the non-LOCA transients where the HLLMS would Indicate .a ' level in the hot leg, but not proceed to ICC. Describe how the HLLMS Indications are similar to those in a LOCA event. .

16.. Are the power sources described under Sect. 3.3.1E power sources?

17. 3.4 Describe how the ICC instrumentation will be l~ntegrated into the control

  -                            room Instrumentation. Will all ICC Indications be grouped together? Describe -                       '

the displays of SMM. HLLMS and CETs. Will any,of these Indicatforis be' displayed elsewhere?

18. Describe how the operator is informed to' ignore the HLLMS Indications ,

z when the pumps are running or the system- should not be used.

                              ~                                                                                             '
    .             Q       19. lt has been suggested that monitoring the pump motor current could ,give                        .

an Indication of RCS voiding while the pumps are running. Please provide e

8 .

                 ,     .?    ,       .

an analysis showing tha relation bstwten RCS pump motor currgnt End RCS - void fraction.

20. Suppose an impulse line on one hot leg was broken that would tpnd to drive the Dp transducer full scale. How would this condition be detected?

When would a level be detected in the other leg?

21. In light of the " failure of the Dp instrurrIentation used for level measurement in the pressurizer at TMI-2. Justify locating the HLLMS Dp transducers in-

                                                               ~ ~                                                        . . ,

containment. . - -- -- " - 22, Please provide specifications for the proposed Dp transducers. ~

23. Please provide an analysis to show the effects of flashing or dissolved .

gases in the impulse. lines. . i

24. Describe, the methods propos's for glgnal isolation in the ICC - -

Instrumentation. .

25. Describe the alarm set points and how selected. . .

26. Describe the modifications that would be required to Install a' reactor vessel level monitoring system across the vessel using an existing in-core .

Instrument guide tube and an upper head vent. .

27. A secondary requirement of NUREG-0737 is for the ICC Instrumentation, system to monitor recovery from transient events, if the event were a large break of a hot leg, how would the ICC system monitor recovery?

28. Under Sect. 5.0. 'descrlDe the confirmatory actions the operator would take d to prevent an ICC event. ' '

29. Please provide a detailed analysis of the level measurement uncertainties associated with the HLLMS. This analysis should include not only an ove'rall ,

estimate of the measurement uncertainty, but estimates of each contributing factor, i.e. temperature of the impulse lines, common mode pressure effects on the ' differential pressure transducer., and uncertainties associated with the transducer. 9

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2 - FROM- - ACTION CONTROL DATES CONTROL NO.

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                                                                                      '2 i DATE OF DOCUMENT""'

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                                                                                      @f'If h j        %J XECUTIVE E        DIRECTOR DESCRIPTION                                                                                         OTsER O TETTER 0 uEuo O REPORT O OTsER sPECIAL INSTRUCTIONS OR REMARKS Reg sta N fafteru Ouke Power of status cf its 5/25/82 submittal concernies a                                     PRIORITY proposed unter inventory monftering systes flor oconee Telephone is 0.K.,1f approprfate -

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