ML20147A689

Responds to NRC Re Violations & Deviations Noted in Insp Repts 50-338/87-39 & 50-339/87-39.Corrective Actions:Emergency Operating Procedures ES-0.2A,ES-0.2B & ES-0.3 Revised to Include Curves Plotted from Tech Specs

ML20147A689
Person / Time
Site:	North Anna
Issue date:	02/26/1988
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
88-060, 88-60, NUDOCS 8803010296
Download: ML20147A689 (10)

Text

l VIRGINI A ELucTHIC AND PownN COMPANY HIcnnown,VIHOINIA 200 01 W. L. ST EWA RT w2'llEl.?"'o.. February 26, 1988 U. S. Nuclear Regulatory Comrrission Serial No.88-060 Attention: Document Control Desk NAPS /GGH Washington, D.C. 20555 Docket Nos. 50-338 50-339 License Nos. NPF-4 NPF-7 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 NRC INSPECTION REPORT NOS. 50-338/87-39 AND 50-339/87-39 We have reviewed your letter of January 27, 1988 which referred to the inspection conducted at North Anna between November 16, 1987 and November 20, 1987 and reported in Inspection Report Nos. 50-338/87-39 and 50-339/87-39.

Responses to the Notice of Violation and Notice of Deviation are provided in the attachment.

l We have no objection to this correspondence being made a matter of public record. If you have any further questions, please contact us.

Very truly yours, SA <

L. Stewart Attachments cc: U. S. Nuclear Regulatory Commission 101 Marietta Street, N. W.

Suite 2900 t Atlanta, Georgia 30323 Mr. J. L. Caldwell NRC Senior Resident inspector North Anna Power Station o\

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8803010296 880226 PDR ADOCK 05000338 0 __pCD

ATTACMENT REPLY TO THE NOTICE OF VIOLATION REPORTED DURING THE NRC INSPECTION CONDUCTED BETWEEN NOVEMBER 16. 1987 AND NOVEMBER 20 1987 INSPECTION REPORT NOS, 50-338/87-39 AND 50-339/87-39 NRC COMENT During the Nuclear Regulatory Commission (NRC) inspection conducted on November 16-20, 1987, a violation of NRC requirements was identified. In accordance with the "General Statement of Policy and Procedure for NRC Enforcement Actions," 10CFR Part 2, Appendix C (1987), the violation is listed below:

10 CFR 50, Appendix B, Criterion V, requires that instructions, procedures, or drawings shall include appropriate quantitative or qualitative acceptance criteria for determining that important activities have been satisfactorily accomplished. North Anna Technical Specification 6.8.1 requires that written procedures shall be established, implemented and maintained covering the activities referenced in Appendix A of Regulatory Guide 1.33, Rev. 2, February 1978.

Regulatory Guide 1.33 includes procedures for combatting emergencies and other significant events. Technical Specification Figure 3.4.3 delineates North Anna Power Station Reactor Coolant System Cooldown Limitations.

Contrary to the above, Emergency Operating Procedures (E0Ps) used by the licensee for natural circulation cooldown are inadequate in that the quantitative cooldown curves in the natural circulation cooldown procedures exceed those specified in Technical Specification Figure 3.4.3, Cooldown Limitations. These E0Ps include: ES-0.2A, Natural Circulation Cooldown With Shroud Cooling Fans, Rev.1; ES-0.28, Natural Circulation Cooldown Without Shroud Cooling Fans, Rev. 1; and ES-0.3, Natural Circulation Cooldown With Steam Void in Vessel (with RVLIS),

Rev. 1.

This is a Severity Level IV violation (Supplement I).

RESPONSE

1. ADMISSION OR DENIAL OF THE ALLEGED VIOLATION:

The violation is correct as stated.

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2. REASON FOR THE VIOLATION:

The Reactor Coolant System (RCS) cooldown curve used in Emergency Operating Procedures (E0Ps) ES-0.2A, "Natural Circulation Cooldown With Shroud Cooling Fans", ES-0.28, "Natural Circulation Cooldown Without Shroud Cooling Fans", and ES-0.3, "Natural Circulation Cooldown With Steam Void in Vessel (with RVLIS)" was calculated from the cooldown curve in Technical Specification Figure 3.4.3. However, this curve was incorrectly interpreted to be based on RCS average temperature. It was desired to present cooldown limits based on RCS cold leg temperature in the E0Ps. Based on an assumed core delta T of 30*F for natural circulation conditions, the Technical Specification curve was adjusted to derive the cold leg curves for ES-0.2A, ES-0.2B and ES-0.3.

The assumption made when the cooldown procedures (Rev. 1) were written, that Technical Specification Figure 3.4.3 was based on RCS average temperature, was in error. The Technical Specification curve is actually based on RCS cold leg temperature, although this is not stated explicitly on Figure 3.4.3. Based on additional review, we have determined that these curves were submitted to the NRC on April 30 1985 as part of a Technical Specification change which had as its basis, reactor vessel capsule evaluations. These evaluations involved establishing limits for temperature at the vessel wall which correspond to RCS cold leg temperature. The curve derived for the Technical Specifications, therefore, represents cold leg temperature limits versus average temperature limits.

3. LORRECTIVE STEPS WHICH HAVE BEEN TAKEN AND THE RESULTS ACHIEVED:

On December 9, 1987 the nonconservatism in ES-0.2B was noted in the operations shift orders along with instructions to follow the Technical Specification curve, and on the following day a Station Deviation Report was submitted. Emergency operating procedures ES-0.2A, ES-0.2B and ES-0.3 were revised on December 18, 1987 to include curves plotted directly from the Technical Specifications, and the temperature axis has been specifically labeled "Cold Leg".

A request for a license amendment to clearly label Technical Specification Figure 3.4.3 has been initiated.

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4. CORRECTIVE STEPS WHICH WILL BE TAKEN TO AVOID FURTHER VIOLATIONS:

No further corrective action is required.

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5. THE DATE WHEN FULL COMPLIANCE WILL BE ACHIEVED: ,

Full compliance has been achieved based on the revisions made to the Emergency Operating Procedures. The revision to the Technical Specification curve 3.4.3 will be pursued to more accurately label the curve axis.

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NOTICE OF DEVIATION The following deviation was identified during a Nuclear Regulatory Commission (NRC) inspection conducted on November 16-20, 1987.

On July 1,1983, the licensee submitted a Procedure Generation Package (PGP) for Emergency Operating Procedures (EOPs) to the NRC. In that submittal, the licensee committed to implement the Westinghouse Owners Group (WOG) Emergency Response Guidelines (ERGS), Rev.1, as approved by the NRC. In addition, the licensee's PGP required that justification of any significant deviaticn from an ERG step and justification of all E0P setpoints be documented. The licensee uses a Step Deviation Document (SDD) for this documentation. The licensee's PGP also required that controls and displays referenced in E0Ps be identified to assist the operator in accurate and quick identification.

Contrary to the above, on November 30, 1987, the licensee's SDD for procedure ES-0.2B, Natural Circulation Cooldown Without Shroud Cooling Fans, Rev. 1, failed to document justification of a significant departure from the ERG. Step 20 of procedure ES-0.28 directed the operators to perform an isothermal depressurization following an 8-hour soak period. This represented a significant departure from the WOG ERGS wherein the operators are directed to continue cooling down, following the soak period, while maintaining 200*F subcooling. The RCS depressurization method used in step 20 of ES-0.2B resulted in significantly less upper head subcooling than in the ERG procedure frus which it was derived. This step deviation was not identified or justified in the licensee's SDD.

Also, the licensee's S00 failed to ida tify the use of different setpoints. The minimum temperature / pressure cooldown curve shown in Attachment 1, Pressure / Temperature Limits for Cooldown, to ES-0.2B was less conservative than the cooldown curve defined by Technical Specifications, Figure 3.4.3. Other setpoints contained in ES-0.2B were different from those used in the ERG (including cooldown rate; subcooling margin; and holdpoint pressure, temperature, and time).

These setpoint differences were not mentioned in the licensee's 500.

Finally, the licensee's E0Ps for natural circulation cooldown ES-0.2A, Natural Circulation Cooldown With Shroud Cooling Fans, Rev.1; ES-0.28, Natural Circulation Cooldown Without Shroud Cooling Fans, Rev. 1; and ES-0.2, Natural Circulation Cooldown With Steam Void in Vessel (with RVLIS), Rev. 1 failed to identify controls and displays to be used in maintaining cooldown pressure and temperature limits in that Attachment 1, Pressure / Temperature Limits for Cooldown, did not indicate which temperature instruments are to be used.

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RESPONSE

1. ADMISSION OR DENIAL OF THE ALLEGED DEVIATION:

Virginia Electric and Power Company acknowledges that for the three cooldown procedures in question, there was a deviation from the Procedure Generation Package (PGP) for failing to indicate which instruments are to be used in maintaining the cooldown pressure and temperature limits as defined by the cooldown curves. We also acknowledge that for procedure ES-0.2B, there was a deviation from the PGP for failing to provide documentation within the Step Deviation Document (SDD) to justify setpoints different from those specified in the WOG documents. The basis for the differences was provided in an E0P setpoint document rather than the SDD, and therefore, the deviation was not for failing to document the changed setpoints, but for failing to properly cross reference the setpoint document in the SDD.

Virginia Electric and Power Company denies that there is a deviation for failure to document a significant deviation by performing an isothermal depressurization. As described below, there is no significant deviation.

The nonconservatism in the minimum pressure / temperature curves in the Emergency Operating Procedure (E0Ps) in relation to the Technical Specification minimum pressure / temperature curve is addressed in the response to the Notice of Violation.

2. REASON FOR THE ALLEGED DEVIATION:

The omission of reference to the required instrumentation for determining compliance with the cooldown curve was an oversight. Failure to document the setpoints was caused by improper cross referencing eith E0P support documents. The justification for the various setpoints for the Natural Circulation Cooldown procedures were fully documented in the setpoint package.

During the writing of the E0Ps, the setpoint justification package '

developed into a separate document. It is used along with the Step Deviation Document and the Westinghouse Owners Group (WOG) Emergency Response Guidelines (ERGS) Background Documents, to provide the technical basis for the E0Ps. The setpoint justification package addresses in considerable depth the setpoints used in the Natural Circulation Cooldown procedures as well as the procedure actions. For these reasons, it was not transferred directly into the SDD. However, this resulted in a change in the methodology presented in the PGP. The 500 should have provided reference to the setpoint package for this documentation.

The basis for our statement that there are no significant deviations between natural circulation cooldown procedure ES-0.2B and the WOG ERGS is derived from a comparison made between the generic methodoloay and the process used in the North Anna procedure. The Westinghouse Owners ,

Group Emergency Response Guidelines Background document defines operating limits for a generic plant design which are designed to maintain subcooling in the reactor vessel upper head during a plant cooldown on natural circulation. They describe four distinct phases of the plant cooldown. The generic limitations corresponding to the North Anna upper head design are shown below for each of the four phases: '

PHASE LIMITATIONS (w/o CRDM Fans) l

1. Cooldown to RHR Temperature (350*F) 25'F/Hr Max Cooldown Rate 200*F Subcooling at core exit, plus allowance for process instrumentation accuracy.

2. Isothermal Depressurization to RHR Wait 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> Pressure (400 psig)

3. Cooldown to Cold Shutdown (200'F) Maintain RHR Operating Pressure

4. Depressurize to Containment Pressure Wait 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> These limitations were derived from thermal hydraulic analyses of the upper head fluid temperature during natural circulation. The Emergency Response Guidelines recognize the need to adapt these generic limitations through the calculation of plant specific setpoint values which address plant specific considerations that could not be included in the development of the generic guidelines, such as Technical l Specification pressure / temperature limits, operation of the Cold Overpressure Mitigation System (COMS), and actual RHR operating conditions.

When the generic setpoint values are applied to North Anna, two conflicts develop during Phase 1 of the cooldown. First, if 200'F subcooling is maintained at the core exit, including allowance for process instrumentation accuracy, insufficient operating margin is available to maintain pressure and temperature within Technical Specification limits. Secondly, Technical Specifications may require the COMS to be placed in service when the hot leg temperature is less than 370'F. Reactor coolant pressure must, therefore, be decreased to less than the COMS pressure setpoint before continuing the cooldown.

Plant specific setpoint values for North Anna were calculated to resolve these conflicts while maintaining adequate subcooling in the reactor vessel head. To determine the pressure / temperature limits for Phase 1, the calculated upper head fluid temperatures were extrapolated to slower cooldown rates, as described in the E0P Setpoint Document. Allowable pressures were determined such that the minimum subcooling in the vessel

upper head, including process instrument accuracy, was greater than that specified in the generic guidelines prior to the isothermal depressurization (60*F). The analysis demonstrates that a subcooling margin of 150'F at the core exit plus allowance for process instrumentation accuracy results in the same minimum subcooling margin in the vessel upper head region prior to the isothermal depressurization as the generic limitation if the cooldown rate is limited to less than i 15'F/hr.

The slower cooldown rate limitation for North Anna results in a lower upper head fluid temperature at the end of Phase 1 than the generic I

analysis predicts. In addition, the cooldown is stopped at a hot leg I temperature greater than 350*F until the reactor coolant pressure can be decreased to a pressur9 where the COMS can be placed in service.

Therefore, it was necessary to adjust the generic wait period prior to the isothermal depressurization Phase 2. A plant specific wait period was calculated by extrapolating the generic wait period and analysis results to the plant specific initial upper head fluid temperature and i hot leg fluid temperature. This analysis is also described in the E0P Setpoint Document. The analysis indicates that a wait period of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for North Anna results in approximately the same subcooling margin in the upper head at the end of the isothermal depressurization as the 9 hour1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> wait period for the generic plant.

The generic guidelines do not provide explicit margin following the isothermal depressurization in Phase 2 to ensure upper head subcooling when process instrumentation accuracy is considered. However, margin is implicit in the calculated upper head fluid temperature including: 1) a conservative upper support plate design relative to North Anna, i.e.,

inverted top hat vs flat, 2) no credit for natural convection cooling during the wait period, and 3) no credit for conduction cooling during Phase 1.

The generic limitations for Phase 3 and Phase 4 were used for these portions of the cooldown since no plant specific conflicts existed.

The natural circulation cooldown limitations for North Anna are summarized below for each of the four phases:

PHASE LIMITATIONS (w/o CRDH Fans)

1. Cooldown to COMS Actuation (370*F) 15'F/Hr Max Cooldown Rate, 150'F Subcooling at core exit plus allowance for process instrumentation

, accuracy.

2. Isothermal Depressurization (400 psig) Wait 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />

3 PHASE LIMITATIONS (w/o CRDM Fans)

3. Cooldown to Cold Shutdown Maintain RHR Operating Pressure (between 350 and 400 psig) r

4. Depressurize to Containment Pressure Wait 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> Based upon our evaluation, we conclude the following: ,

1. The North Anna natural circulation cooldown procedure (ES-0.2B) conforms to the corresponding generic guideline with no significant  ;

deviation in strategy, execution, or intent. - '

2. The plant specific natural circulation limitations maintains approximately the same ubcooling margin in the reactor vessel upper head region as the generic guidelines through all phases of the .

cooldown. This includes allowance for process instrumentation accuracy as directed by the generic guidelines.

3. CORRECTIVE STEPS TAKEN AND RESULTS ACHIEVED:

The pressure / temperature cooldown curves for the three cooldown procedures have been corrected and the use of cold leg temperature instrumentation was indicated. ,

We have reviewed the E0P supporting documentation including the Step Deviation Documents and the setpoint package associated with the natural circulation cooldown E0Ps to insure that the necessary documentation is i provided for step and setpoint deviations from the WOG ERGS. Our basis documentation and the associated analysis for the isothermal cooldown performed in ES-0.2B were reviewed. Based on our review of this analysis as summarized in section 2 of this response, the use of the '

North Anna cooldown procedure maintains approximately the same margin to voiding in the reactor vessel upper head region as the generic i guidelines for all phases of the cooldown. Therefore, we have no plans to revise our process for performing an isothermal depressurization as described in procedure ES-0.28.  !

4. CORRECTIVE STEPS WHICH WILL BE TAXEN TO AVOID FURTHER DEVIATIONS:

The balance of the E0Ps and the setpoint package will be reviewed during the next review cycle to ensure that deviations from WOG ERGS are properly documented. If any cases of inadequate documentation are  ;

identified as part of other revisions being made to the E0Ps, they will i be addressed as they are identified. l l

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l In order to clarify the relationship between the Step Deviation Documents and the setpoint package, the Step Deviation Documents will be annotated to reference the setpoint package as appropriate.

A procedure generation and maintenance system has been purchased which will automatically cross-reference and insert setpoints from the setpoint package database into the procedures when printed or updated. '

This will reduce the probability of a procedure writer improperly altering a setpoint by typographical error or by failure to refer to the setpoint package for the correct setpoint.

5. DATE WHEN FULL COMPLIANCE WILL BE ACHIEVED:

The E0Ps addressing natural circulation cooldown are now in compliance with PGP requirements. The review of the remaining E0Ps and the cross referencing of the Step Deviation Document to the setpoint package will be completed by June 1,1988. The procedure generation and maintenance system will also be installed and fully functional by June 1,1988.

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