ML20210H828

Forwards Supplemental Info to Util 830418 & 851010 Responses to Generic Ltrs83-10d & 85-12 Re Reactor Coolant Pump Trip Issue,In Response to NRC 860422 Interim Rept

ML20210H828
Person / Time
Site:	Beaver Valley
Issue date:	09/05/1986
From:	Sieber J DUQUESNE LIGHT CO.
To:	Thompson H Office of Nuclear Reactor Regulation
References
86905, GL-83-10, GL-85-12, TAC-49695, NUDOCS 8609260338
Download: ML20210H828 (7)

Text

____ - ______.

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'Af Telephone (412) 393-6000 Nuclear Group sNppingport, PA 15077-0004 #

U. S. Nuclear Regulatory Commission Mr. Hugh L. Thompson, Director Division of PWR Licensing - A Washington, DC 20555

Reference:

Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Interim Report on Reactor Coolant Pump Trip Criteria Gentlemen:

The attachment to this letter provides supplemental information to our responses dated April 18, 1983 and October 10, 1985 to Generic Letters83-10d and 85-12, respectively, regarding the Reactor Coolant Pump Trip Issue. This submittal is in response to the Staff's Interim Report transmitted by letter dated April 22, 1986. The Item designations correspond to those in the Staff's Interim Report.

If there are comments to the attached information, please contact myself or members of my staff.

Very truly yours, J. D. Sieber I Vice President Nuclear Operations cc: Mr. W. M. Troskoski, Resident Inspector )

U. S. Nuclear Regulatory Commission Beaver Valley Power Station Shippingport, PA 15077 U. S. Nuclear Regulatory Commission c/o Document Management Branch Washington, DC 20555 Director, Safety Evaluation & Control Virginia Electric & Power Company P.O. Box 26666 One James River Plaza j Richmond, VA 23261 0\

8609260338 860905 fDR ADOCK 05000334 PDR

ATTACHMENT BVPS-1 Response to the Interim Report on Reactor Coolant Pump Trip Criteria A. Determination of RCP Trip Criteria The staff requests that the licensee provide a summary of the selection process which illustrates the rationale leading to the selected trip criterion.

Response

The selection process for the RCP trip criterion supported the i development of the BVPS-1 symptom oriented Emergency Operating  ;

Procedures (EOPs) with the purpose of satisfying the requirements l of Generic Letter 83-10d regarding the setpoints for RCP trip. '

The Westinghouse Owners Group (WOG) guidance contained in the report, " Evaluation of Alternate RCP Trip Criteria," was reviewed, and, cccordingly,'the plant specific calculations were l performed for each of the three'41 ternate setpoints of the RCP l trip criteria as, appropriate for BVPS-1. The above WOG report' was forwarded to the NRC under Transmittal Number'OG-110, dated December 1, 1983, and the information from the report was incorporated into the WOG Emergency Response Guidelines (ERGS),

Revision 1, which were used to develop the BVPS-1 EOPs. The effort represented by these and the other generic documentation pertaining to the RCP trip issue to a certain extent established the selection process, including a calculational methodology to be used on a plant specific basis for determining the alternate RCP trip setpoints.

The primary purpose of the setpoint calculations was to determine which of the alternate criteria satisfied the discrimination capability on a plant specific basis for the Small Break Loss of Coolant Accident (SBLOCA), and the Steam Generator Design Basis Tube Rupture and other Non-LOCA Accidents. Once the calculations were completed, the selection process focused on those setpoints which best satisfied both the discrimination capability and the qualification of the respective instrumentation. Although the discrimination capability was satisfied for BVPS-1 by the RCS subcooling and the Secondary Pressure Dependent RCS pressure criteria, the latter was chosen as the most appropriate due to its instrumentation qualification. It is not detrimental that other desirable characteristics such as redundancy and backup diversity are associated with this instrumentation.

It can be shown that the discrimination capability of the selected setpoints is maintained and, in fact, not significantly affected if the calculational uncertainties, which were provided in Item A3 of our October 28, 1985 response to Generic Letter 85-12, are algebraically added to the limiting results of the SGTR and Non-LOCA Analysis of 350 psi primary / secondary differential pressure. The instrumentation uncertainties have been included in the BVPS-1 setpoint determination as recommended by the WOG calculational methodology.

Att'achmtnt Page 2 Finally, for the criteria selection process at BVPS-1, an evaluation which compares the degree of usability of the alternate RCP trip setpoints and instrumentation did not become a l deciding factor. For example, included in such an evaluation could have been a comparison of the relative ease for an operator to base his decision to trip the RCPs solely on one variable, i.e., primary pressure, rather than the differential between two variables as is the case for BVPS-1. However, as shown above, the criterion using only the primary pressure for the setpoint was not a viable alternative.

Al. Instrumentation Identification and Qualification

, Response The Licensee concurs with the Staff's evaluation.

A2. Instrumentation Uncertainties for Both Normal and Adverse i Containment Conditions

~

Response

The Licensee concurs with the Staff's evaluation and, la general, with the Staff's perception of the telephone conference call response. Provided below is clarifying and supplemental information which includes consideration of i permanent damage that may have occurred to instrumentation due to exposure to an adverse environment.

The following information provides clarification of the BVPS-1 basis for the selection of the adverse containment parameters. The selection of the pressure and radiation values which determine adverse containment conditions is based on the ERG defined values. Included in the ERG definition is the condition that, if the containment integrated radiation exceeds LEER, the EOP adverse containment parameter setpoint must be implemented by the operator. Adverse containment is therefore defined in the BVPS-1 EOPs as: 1) containment pressure greater than 5 psig or, 2) containment radiation greater than lES R/hr. or,

3) integrated containment radiation greater than lE6 R. If none of these containment conditions exist, the EOP normal parameter setpoint is used.

The following addresses permanent damage that may have occurred to instrumentation and how the operators would determine which instruments are providing the proper l indications. The effect of the damage is assumed to be such I that the instrumentation provides indication in the control room which is on-scale and appears valid in comparison to the instrumentation which is operating correctly.

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Att'achmsnt Page 3 As stated above the licensee concurs, in general, with the Staff's perception of the conference call. Specifically, however, it should be noted that the operator could also utilize the three pressurizer pressure indicaticns if the RCS pressure is above approximately 1700 psig in lieu of 1750 psig. As supplemental information, it is also noted that the BVPS-1 Inadequate Core Cooling (ICC)

Instrumentation System has added two new wide range RCS

^

pressure transmitters outside . containment. When the ICC Instrumentation System becomes operational by the end of the

[ sixth refueling outage, these transmitters will provide two

additional RCS pressure indications in the control room.

To assess which secondary pressure instrumentation is operating correctly, the operator could utilize any of the remaining two of the three secondary pressure indications

, for each loop, the additional pressure indications for each

steam line sensed upstream of the trip (steam isolation)

! valves, and the main steam header pressure indication, i unless there has been closure of all steam line isolation

! valves. All of the above indications are located in the control room.

i A3. Uncertainties Associated with the WOG Supplied Analysis Values

Response

The Licensee concurs with the Staff's evaluation.

B. Potential Reactor Coolant Pump Problem Bl. Assurance That Containment Isolation Will Not Cause Problems if it Occurs for Non-LOCA Transients and Accidents

Response

The Licensee concurs with the Staff's evaluation.

B2. Components Required to Trip the RCPs

Response

i The Licensee concurs with the staff's evaluation and the Staff's perception of the telephone conference call response. In addition, confirmation of the response to Generic Letter 83-10d, Item 1.1.b. of the Detailed Response Seciton, is herein provided. The RCP trip criteria selected for BVPS-1 is such that the operator is instructed to trip the RCP before voiding occurs at the RCP.

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. _ _ - - ~ - - -- . _ - - .

At'tachmsnt Pags 4 C. Operator Training and Precedures (RCP Trip)

C1. Description of the Operator Training Program for RCP Trip

Response

The following provides clarification for the RCP trip philosophy as it is used not only in training but also in the BVPS-1 EOPs. The criterion is presented first and then the general conditions under which the criterion applies are briefly described. The specific EOPs where the RCP trip and restart steps are found were summarized in our initial ~

response to Generic Letter 85-12.

] The RCP trip criterion consists of two fundamental parts:

- Successful operation of the Safety Injection System, and

! - Selected plant parameters reaching critical setpoints.

The operator is instructed to verify both parts whenever i tripping of the RCPs according to the criterion is required by the appropriate steps in the EOPs. Therefore, the critical setpoint for BVPS-1 of RCS pressure 145 psi greater than the highest S.G. pressure for normal containment conditions or 510 psi for adverse containment conditions is understood as only the setpoint part of the criterion. This understanding should resolve the apparent inconsistency in our initial response to this item.

The following provides a brief explanation of the regime of applicability of the RCP trip criteria. The provisions for RCP restart considering SBLOCA is included. It is noted that the explanations are general since BVPS-1 EOPs follow the guidance of the WOG ERGS. The Special Provisions for

RCP restart steps which occur in the Function Restoration Guidelines (FRGs) are also not discussed herein. However, detailed explanations are provided in ERGS.

j

! The conditions where the RCP trip criterion applies are:

1 - Following reactor trip and safety injection actuations

initiated from power operation, and 1'

- During recovery actions or at hot standby conditions before initiation of an operator controlled RCS cooldown.

Conditions following a safety injection actuation initiated from cold shutdown, hot shutdown or startup conditions, and  ;

refueling are not considered in the context of applic-ability.

l i

. Attachment Page 5 In general, therefore, the RCP trip criterion does not apply

after an operator controlled RCS cooldown has been

! initiated. When an operator controlled cooldown has been i initiated, sufficient time from reactor trip should have

! expired such that any subsequent failure beyond that causing reactor trip should not require RCP trip in order to ensure acceptable clad temperature, even if it is a SBLOCA.

Also, prior to restarting an RCP, the Optimal Recovery l Procedure (ORP) of the EOPs ensure that there is no SBLOCA concern which would require RCP trip. If RCS subcooling i exists and pressurizer level is on span, then there is not a

! SBLOCA concern of excessive inventory loss through a 1

postulated break. These two parameters are addressed in the l EOPs either explicitly whenever Safety Injection has been

! initiated or implicitly when Safety Injection is terminated since RCS subcooling and pressurizer level are part of the l Safety Injection termination and reinitiation criteria. An

exception to the above occurs in Contingency Action 3.3, "SGTR Without Pressurizer Pressure Control" where only

) subcooling is required and restarting an RCP is the only '

means of restoring pressure control to recover from a SGTR.

i Our previous response to Generic Letter No. 85-12, Item B.1, i provides the manner in which it is assured that the operator i will take the appropriate action to stop the RCPs after termination of CCR flow upon a CIB signal. Included therein i is a summary of the alarms associated with the CCR system i and the RCPs. It is noted that if RCP operation becomes

]

desirable, the symptom-oriented EOPs provide for RCP restart under the appropriate conditions. However, if seal

! injection flow and thermal barrier cooling has been lost, the RCPs shall not be restarted prior to a status evaluation. The EOPs contain caution statements to this

effect. Also, in the EOP contingency action procedures, j ECA-0.1 and 0.2, which address the loss of all AC power, the operators are both cautioned and provided with instructions

, to slowly initiate RCP thermal barrier cooling and seal l injection flow. Therefore, the RCP related alarms in the

control room, the caution statements in the EOPs, and the

! operator training, relative to conducting RCP operations i properly and to the importance of the RCP trip issue,

, provide substantial assurance that unacceptable thermal j stresses would not be placed on the RCPs. Notwithstanding, 1 action has been taken to include additional guidance in the i EOPs prior to RCP restart which will provide further I assurance that unacceptable RCP thermal stresses will not be j inadvertently caused by the improper reinitiation of RCP j thermal barrier cooling and seal injection flow. It is

! recalled here for completeness that certain Function  ;

} Restoration Procedures contain special RCP restart steps '

l 1

wherein, although RCP support conditions are desired, one or more RCPs as necessary may be restarted if RCP support ,

conditions cannot be established. l 1

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Attachmsnt l

'Pagn 6 j The following clarifies the tripping of the RCPs upon CIB actuation. The RCPs are tripped upon CIB actuation because the Reactor Plant Component Cooling (CCR) Water Flow to the RCPs is terminated at that time. Supplemental information on the selection of the appropriate RCP setpoint value based upon normal or adverse containment conditions as indicated by the parameters values of 5 psi and 1E5 R/hr is provided above under Item A.2.

C2. Identification of Procedures Which Include RCP Trip Related operator

Response

The Licensee concurs with the Staff's evaluation and the Staff's perception of the telephone conference call response.

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