ML20028H205

Responds to NRC 901011 Ltr Re Violations Noted in Insp Repts 50-327/90-29 & 50-328/90-29.Corrective Action:Power Range Channels Recalibrated on 900608

ML20028H205
Person / Time
Site:	Sequoyah
Issue date:	11/15/1990
From:	Medford M TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9011160115
Download: ML20028H205 (6)

Text

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w TENNESSEE VALLEY AUTHORITY l CH ATTANOOGA, TENNESSEE 37401 6N 38A Lookout Place U.S. Nuclear Regulatory Commission WOV~ 151990  ;

ATTN: Document Control Desk Washington, D.C. 20555 I Gentlemen: j In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50 328 l SEQUOYAH NUCLEAR PLANT (SQN) - NRC INSPECTION REPORT NOS. 50-327, 328/90 29 -

RESPONSE TO NOTICE Of VIOLATIONS 50 327, 328/90-29 01, AND 50 327, 328/90 29 02 Enclosed is TVA's . reply to B. A. Wilson's letter to 0. D. Kingsley, Jr., dated o October 11, 1990, which transmitted the subject notice of violations.

In the inspection report, NRC expressed concern on the staffing and ex3erience of the Reactor Engineering unit. TVA has likewise been concerned on tie loss of experience in the section, in response to this concern, TVA has focused attention on obtaining personnel who can meet the high performance standards required of these positions. The new Reactor Engineering supervisor, though an electrical engineer rather than a nuclear engineer, recently completed the seven-week Westinghouse Electric Corporation Station Nuclear Engineer program.

The new supervisor also has approximately ten years of experience in '

supervising engineers in previous Preoperational Test, Modifications, Maintenance, and Technical Support supervisory roles. This individual was ,

specifically selected for his management skills in providing oversight of critical functions. The three engineer positions in the section are now permanently filled by a former SON reactor engineer and shift technical advisor j and two former TVA nuclear fuels engineers. Management will continue to assess t the effectiveness of these changes to ensure quality performance of the Reactor Engineering duties.

No commitments beyond those identified in Licensee Event Report 50-327/90011,- -

Revision 1, are made.in this letter.

If you have any questions concerning this submittal, please telephone "

M. A. Cooper at (615) 843 6422.

Very truly yours, TENNESSEE VALLEY. AUTHORITY .

$ lj -/

Mark 0. Medford, Vice President Nuclear Assurance, Licensing

& Fuels Enclosure =

cc: See page 2-

[0M$0bb!!bObbbb27 O An Equal Opportunity Employer [  !

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U.S. Nuclear Regulatory Commission DN7/151990 cc (Enclosure):

Ms. S. C. Black, Deputy Director Project Directorate 11-4 U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. J. N. Donohew, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 NRC Resident inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region 11 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323

. ENCLOSURE 1 RESPONSE TO NRC INSPECTION REPORT NOS. 50-327/90-29 AND 50 328/90 29 B. A. WILSON'S LETTER TO 0. D. KINGSLEY, JR.,

DATED OCTOBER 11, 1990 Violation 50 327. 328/90-29-01 Technical Specification (TS) 2.2.1 (Table 2.21, Item 2) requires that the Limiting Safety System Setting (LSSS) for the power range J neutron flux low trip setpoint be less than or equal to 26 percent of Rated Thermal Power and that the LSSS for the power range neutron flux high trip setpoint be less than or equal to 110 percent of Rated Thermal Power.

TS 6.8.1.c requires that written procedures shall be p ovided for surveillance and test activities.

Contrary to the above, procedure Technical Instruction (TI)-81 (used for both units), when first issued in 1984, and when subsequently reissued as procedures 1/2-PI NXX-092 001.0, was not correct and did not properly follow vendor recommendations to adjust power range instrument channels to account for reduced neutron flux leakage to the detectors. Consequently, when Unit I was started up on May 31, 1990, the low power trip set)oint and the high power trip setpoint were each about 20 percent 11gher than the respective limiting safety system settings, and that situation persisted until June 5, 1990.

This is a Severity Level IV violation (Supplement 1).

Admission or Denial of the Alleaed Violation TVA admits the violation.

Reason for the Violation The technical inadequacy of 1-PI NXX-092-00.1.0, "Prestartup NIS Calibration Following Core Load," that led to the nonconservative calibration of the ocwer range nuclear instrumentation system (NIS) channels during start-up from the Unit 1 Cycle 4 refueling outage, was the result of a technical interpretation error.during the development and subsequent revisions of the pre-start-u) detector current prediction procedure. A review of the power range cali) ration procedure (1 PI-NXX-092-001.0, formerly Tl 81) identified that the procedure has been in error since-originally issued on November 1,1984. As described in Licensee Event Report (LER) 50-327/90011, Revision 1, the pre-start-up calibration procedure incorrectl: utilized beginning of-life (B0L) power

- distribution from the previous cycle (PR old), BOL power distributions for the current cycle.(PR new), and end-of-life (E0L) detector currents from the to calculate the new preliminary detector currents for previous the current cycle (I ol x PR new/PR old = I new). This calculation cycle (1 old) d methodology was thought to be in accordance with the Westinghouse Electric

-Corporation recommendations. As a result of the investigation of nonconservative calibration event, it was identified that EOL power distributions from the previous cycle should be utilized for the calculation.

It is concluded that the error contained in the pre start-up calibration was the result of an incorrect technical decision during the review process. The validity of the equation was evaluated by several nuclear engineers during the evolution of the procedure, and most recently by a senior level reactor engineer and the previous Reactor Engineering supervisor. The conclusions of these reviews and evaluations incorrectly interpreted the Westinghouse information, leading to the technical inadequacy.

Although they do not 5ppear to substantially affect the conclusions drawn, several errors were noted during TVA's review of the inspection report. First, the notice of violatton (NOV) ide6tifies the low and high power range neutron flux LSSSs to be less tht.. or equal to 26 percent and 110 percent, respectively. The Unit 1 LSSSs for thase tri) functions are 27.4 percent and 111.4 percent. The NOV also indicates that tie nonconservative condition existed until June 5, 1990. The nt,v.tsiservative condition of the power range channels existed until June 6, 1990.

Additional details concerning this event were provided in LER 50-327/90011, Revision l'.

Corrective Steos That Have Been Taken and Results Achieved The power range NIS channels were adjusted on June 6,1990, as part of the normal power escalation process. The power range channels were recalibrated on June 8,1990, to reflect the new 100 percent power detector currents.

LER 50-327/90011 and this violation have been reviewed with the Reactor Engineering staff. This review addressed the specific impacts of the nonconservative calibration and the generic impacts of misinterpreting vendor information.

Additionally, Westinghouse, Corporate Nuclear Fuel, and Institute of Nuclear Power Operations (INPO) personnel have performed an independent review of Reactor Engineering procedures for technical adequacy. The results of .this review were incorporated into the Unit 2 procedures before use during restart from the Unit 2 Cycle 4 refueling outage.

, .C'orrective Steos That Will be Taken to Avoid Further Violations As committed in LER 50-327/90011', Revision 1, Procedure 2-PI-NXX-092-001.0 (Unit 2) was revised before use during start-up from the Unit 2 Cycle 4 refueling outage to require the use of E0L NIS detector currents and fuel assembly power fractions from the previous cycle and the corresponding BOL fuel assembly power fractions for the current cycle. A conservative factor of 0.8 was used to account for prediction uncertainties associated with fuel element power factors and detector current measurement. This factor is consistent with conservatisms used at other Westinghouse facilities. Procedure 1-PI NXX 092-001.0 (Unit 1) will be

.similarly revised before use during start-up from the Unit 1 Cycle 5 refueling outage.

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Date When Full Comoliance Will be Achieved i TVA will be in full com)11ance by restart from the Unit 1 Cycle 5 refueling outage when tie Unit 1 procedures are revised.

l Violation 50-327. 328/90 29-02 TS 6.8.1.c requires that written procedures shall be implemented for surveillance and test activities.

L (1) Procedure 0-PI-NXX-092-001.0, Incore-Excore Detector Calibration, indicates, by example, that three full corc flux maps and eight quarter core flux maps be obtained for analysis, but does allow the number of maps to be reduced at the discretion of the test director. The procedure also requires that the maps be obtained at power levels above 70 percent Rated Thermal Power.

Contrary to the above:

(a) Procedure performed for Unit 1 in the period June 7 to l July 26, 1990 and August 4,1990, used only two maps, both full core.

Licensee personnel acknowledged that this had become common practice on both. units. Two maps are insufficient to demonstrate that a ,

linear relationship exists between the incore and excore axial power distributions, the point of the test.

l.

(b) The procedure performed in the period from June 7 to July 26,1990, was performed at about 30 percent Rated Thermal Power, and a procedure was not performed at the required power level until August 4, 1990, after extended operation above 70 percent rated ,

thermal power.

(2) Procedure 0 SI-NXX-092 079.0 requires independent verification L of test results in step 7.0(2).

l Contrary to the above, the independent verification step was not signed off for Unit 1 procedures performed on June 8, 1990, and

' June 15-20, 1990. >

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

Mpssion or Denial of the alleaed Violation TVA admits the violation.

l t

..;. 4 Reason for the Violation The examples of failing to follow procedure cited above are the result of a lack of attention to detail on the part of the responsible reactor engineer at that time and a lack of management attention and oversight in Reactor Engineering.

TVA agrees that, as a contributing cause to Example 1, Procedure 0-PI-NXX-092-001.0 contained excessive-latitude that allowed the responsible reactor engineer, at his discretion, to routinely perform only two flux maps. This latitude, in combination with a general lack of attention to detail, led to the cited violation.

Corrective Steos That Have Deen Taken and Results Achieved Since the time of the cited examples of failure to follow procedures, staffing changes %ve occurred in the Reactor Engineering section such that the Reactor Engins er:ng personnel invo'.ved with i.he events are no longer employed by TVA. The importance of procedural cort.pliance has been reviewed and stressed with the current Reactor Engineering staff. Additionally, a new Reactor Engineering supervisor is in place and was specifically selected for his management skills in providing oversight of critical functions.

Each of _ the examples of failure to follow procedure were reviewed to ensure

-no technical consequence exists, i.e., administrative noncompliance only.

0-PI-NXX-092.001.0 us reviewed and revised appropriately to eliminate the excessive latitude previously given the test director. The intent will still allow for test director discretion, but within established workable bounds.

A minimum of four flux maps are now required, with guidance on whether full

' core or quarter core maps are required.

-CorrectiveleDs The Will be Taken to Avoid Further Violation Quality Assuranc6 Sarvices (Operations & Technical Support) conducted an

< audit of Reactor Engineering activities to assess administrative and technical compliance. The audit encompassed the restart testing associated

-with the Unit 1 Cycle 4 and Unit 2 Cycle 3 refuelir+ outage restarts and surveillance conducted by Reactor Engirering for tr a last six months. A 100

. percent administrative and 10 pet cent technical review was conducted. The audit identified additional administrative noncompliances and minor calculation errors. None of the calculation errors affected the surveillance test acceptance criteria. Reactor Engineering is evaluating the findings and will be taking .the appropriate corrective actions as required for these findings.

k_ ate When Bill Comoliance Will be Achieved TVA is in full compliance. Additional enhancements from the audit findings will be identified and scheduled as required.

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