U-602045, Forwards Response to GL 92-04, Resolution of Issues Re Reactor Vessel Water Level in BWRs Per 10CFR50.54(f). Util Endorses BWR Owners Group Plan,Including Analysis & Testing Program

Forwards Response to GL 92-04, Resolution of Issues Re Reactor Vessel Water Level in BWRs Per 10CFR50.54(f). Util Endorses BWR Owners Group Plan,Including Analysis & Testing Program

ML20118B482
Person / Time
Site:	Clinton
Issue date:	09/25/1992
From:	Jamila Perry ILLINOIS POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-92-04, GL-92-4, U-602045, NUDOCS 9210020248
Download: ML20118B482 (4)

Text

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, iluno<s Power Company

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-*.. CIWon Power Stato)

P,0 Dox 678.-

• , Clinton,!L 61727 l f Tet 217 935 0226 '-

Fax 217 935,4032 J. Stephen Perry i Semor %ce President ILLIN/ SIS- l POWER "-6 2043 L30 92(09-25)-LP -

80.120 September 25, 1992 10CFR50.54(f)

Docket No. 50-461 '

Document Control Desk Nuclear Regulatory-Conunission Washington, D.C. 20555 l

Subject:

Response to Generic i.etter 92-04: Resolution of the lasues Related to Reactor Vessel Water Level in BWRs Pursuant to 10 CFR 50.54(f)

The attachment provides the results of the Illinois Power..(IP) review of the subject Generic Lettec (GL) and includes. IP's response to-the roquested actions contained in the CL.

I hereby affirm that the information in the attachment is correct-to the best of my knowledge.

Sincerely yours, p .

~ W . S. Perry

, . Senior Vice President n

TBE/mfm Attachment cc: NRC Clinton Licensing Project Manager i

NRC Resident Office-Regional Administrator, Region III, USNRC Illinois Department of Nuclear Safety 100119 /90{ ,

9210020248 DR 920925 ADOCK 05000461 ,

PDR

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' Attachment to wo .U 602045 3 p _, - .Page 12 of-3

Subject:

IN inois-Power Response to Generid Letter 92 04

[Subj ect/

Title:

_ Resolution of the Issues Related to' Reactor

= Vessel Water Level . Instrumentation ' in BWRs Pursuant to-10CFR50.54(f)] ,

i

References:

1) Letter, bMROG 92072, G. J. Beck (BWROC) to W. - T.

Russell _(NRC), " Reactor Vessel- Water Level Indication",_

August 12, 1992.

2) BWROG Report, "BWR Reactor Vessel Water Level Instrumentation,* August 2A, 1992 ,

3) Letter, BWROG 92082, C. J. Beck (BWROC) to Document Control Desk (NRG , " Reactor Vessel Water ' Level Instrumentation," September 24, 1992 The following information constitutes the Illinois Power (Clinton. Power Station) response to the specific requested actions in Generic letter 92-04 Eqquested Action l

1. In light- of potential errors resulting from the effects of-noncondensible gas, each licensee should determine:

a. The- impact of potential level indication errors on automatic safety system response during all licensing basis transients - and .

accidents;

b. The impact of potential level indication errors on operators' short and long term actions during and after all. Licensing basis accidents and transients;

c. -The impact of potential level- indication errors on operator .

actions prescribed in emergency operating procedures orf other . -

affected procedures not covered in (b).

1 a- The BWR Owners' Grout (BWROC) provided to the NRC and each of the member utilities a copy.of the report (Reference 2) on BWR Reactor Vessel Water Level Instrumentation, Revision 1, August 28, 1992. This report addresses the safety impact of potential water . level -indication errors on automatic system response'during all 11censin6 basis' transients and accidents. This analysis' ,

is - contained in Section 6.0, Eafety Analysis,'of the report and is summarized.

Inf Suction 2.2, P1 ant Responses to Postulated - Accident Scen2rios. It is Illinois Power's- position that the informa tion - in-- the 'BWROG report. is applicablo'to the design of- Clinton Power Station- (CPS) . This conclusion is t j . based on our review of-the report _and the evaluation made by General Electric as contained .in. Attachment 2 to the-report. Illinois '. Power recognizes that--

there are differences between the designs'of BWR plants and' systems; however, our review of the report and the Attachment 2 conclusions ; reinforce Illinois

i. Power's position that the basic plant responses to the design basis transients and_ accident events (for CPS) are suf ficient_ly described and . bounded by the

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W is 1 w '-W +=-w--s +-~C- " + * -*

Attachment to

• U-602045 Page 2 of 3 report to obviate the need for additional, plant-unique, detailed reanalysis.

Further, this conclusion is reinforced by the fact that Clinton Power Station was licensed to more conservative analytical bases than those that are accepted today by the NRC.

Lb The BWROC report addresses in section 6.9, Operator Responses, the operator actions that could be anticipated in response to potential water 1cvel indication errors. With respect te short term actions, the report notes in Section 6.0 that the automatic safety actions will be performed as necessary. For longer term actions, CPS Operations personnel have been provided the information contained in the BWROG Emer gency Procedures Committee (EPC) recommendation letter of August 19, 1992. This information has been specifically provided to the plant operators and has served to sensitize the operators on the observable phenomena for water level indication during depressurization events. The information provided in the EPC letter is consistent with the CPS philosophy of conservative operation as it recommends the use of the lowest reading from the reactor water level channel (s) when level indication disparitics exist.

Th i. s conservative philosophy concerning water level indication disparities is reinforced in operator training, included in operator training are those conditions where water level cannot be determined based on the available level indication. For this condition, the CPS Emergency Operating Procedures (EOP) provide adequate guidance to the operators to restore and maintain adequate core cooling.

4 1.c As stated in section 6.9 of the report and the 1.b response above, plant operators have adequate guidance information in the present E0Ps. However, the EPC is continuing to revicw the potential need for any additional guidance relating to the Emergency Procedure Guidelines (EPG) to furthcr address the potential water level indication errors. Such review will take into account the information from the BWROG program of analysis and testing established in response to the water-level indication issue. Any further recommended changes to the E0P procedures or additional guidance will be addressed upon completion -

of the review or as such changes are identified. This issue, as well as the BWROC analysis and testing program, is further discussed in the BWROG letter (Reference 3) to the NRC, dated September 24, 1992.

Rentgsred Action 2

2. Based upon the result of (1) above, each licensee should notify the NRC of short term actions taken, such as: ,

a. Periodic monitoring of level instrumentation system leakage; and, ,

b. Implementation of procedures and operator training to assure that potential level errors will not result in improper operatur aCCions.

2.a Existing information about the CPS-specific configuration of the cold leg water level instrumentation has been reviewed, and additional verification will take place during the next refueling cutage, The available information has been providad to the BWROG to be factored into the BWROC testing and

nttachment'to '

V . -U-602045-

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Page 3 of 3.

analysis program described in the BWROG August 12, 1992 letter (Reference 1) to the NRC and in the BWROC' September 24, 1992 letter' (Reference 3) to the NRC. , - The' significance of different characteristics of the configuration ' of cold _ leg water level instrumentation ;(including the effect of leakage) will-not be fully understood until the BWROG pro 5 ram test information is available.

The BWROC incends to share information gained from sampling the reference leg '

water concentration of noncondensible gases. This information potentially will assist in the correlation of plant data to the information coming from

'the Bb10G test program.

At CPS, several actions are being or will be taken. Channel checks of the reactor water level instrumentstion in accordance with the surveillance requirements of the. CPS Technical Specifications will continue to be performed as required. In addition, when the plant is shut down for the next refueling outage (currently scheduled to- begin September 26, 1993), reactor water level indication will be closely observed and will be recorded and tracked with the General Electric Transient Analysis Recording System (CETARS) to see if the ,

" notching" phenomenon observed at some plants occurs at. CPS riuring depressurization, Reactor water level instrument calibration procedures are currently being revised to include steps to check for leakage or evidence of leakage from the reference legs. Additional actions or methods for monitoring Icakage or reference leg / condensing chamber performance are being investigated.

M As discussed in the response to 1.b and 1.c, Illinois Power is training CPS operators on the information contained in the letter from the EPC. 'The response to 1.b and 1.c provides further G scussion regarding procedures and operator training to assure that potential level errors will not result in improper operator actions.

Recuested Action 3 1

3. Each licensee should provide .Its plans and ' schedule for corrective actions, including any proposed hardware modifications necessary to.

ensure the level instrumentation system design is of high functional reliability _ for long term operation. Since this instrumentation plays _

an important role in plant safety and is required. for both normal . and accident conditions, the staff recommends that each ' utility implement its longer term actions to assure a level instrumentation system of high

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functional reliability at the first opportunity but prior to starting up after the next refueling outage commencing 3 uonths- af ter the date of this letter.

3_ . Illinois Power endorses the BWROG plan originally provided in the-BWROCL

-letter to the NRC, dated August 12, 1992 (Reference 1). Illinois Power also reaifirms support of the _ BWROG plan, including the analysis and testing --

- program, by endorsing the BWROC letter _ dated September 24,'1992 (Reference 3).

If ; the BkmOG program indicates that a plant modification is necessary to assure that the level instrumentation is of high functional reliability, a schedule for implementing such a modification will be provided to the'NRC at. l that time.

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