ML20206Q704

Ack Receipt of Informing NRC of Steps Taken to Correct Violations Noted in Insp Rept 50-341/99-02 on 990308

ML20206Q704
Person / Time
Site:	Fermi
Issue date:	05/06/1999
From:	Jeffrey Jacobson NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:	Gipson D DETROIT EDISON CO.
References
50-341-99-02, 50-341-99-2, NUDOCS 9905190203
Download: ML20206Q704 (2)

See also: IR 05000341/1999002

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May 6, 1999

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Mr. D. R. Gipson

Senior Vice President

Nuclear Generation

The Detroit Edison Company

6400 North Dixie Highway

Newport, MI 48166

SUBJECT: NOTICE OF VIOLATION (NRC INSPECTION REPORT 50-341/99002 (DRS))

Dear Mr. Gipson: ,

This will acknowledge receipt of your letter dated April 20,1999, in response to our letter

dated March 8,1999, transmitting a Notice of Violation associated with the design calculation

problem documented in the subject inspection report at Fermi 2. We have reviewed your

corrective actions and have no further questions at this time. These corrective actions will be

examined during future inspections.

Sincerely,

Original /s/ John M. Jacobson

John M. Jacobson, Chief

Mechanical Engineering Branch j

Division of Reactor Safety

Docket No. 50-341

License No. NPF-43  ;

cc: N. Peterson, Director, Nuclear Licensing

P. Marquardt, Corporate Legal Department

R. Gaston, Compliance Supervisor

R. Whale, Michigan Public Service Commission ,

"

Michigan Department of Environmental Quality

Monroe County, Emergency Management Division

Emergency Management Division

Ml Department of State Police

See Attached Distribution

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April 20,1999 DM Mson

NRC-99-0017

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US Nuclear Regulatory Commission

Attention: Document Control Desk

Washington DC 20555

Reference: 1) Fermi 2

NRC Docket No. 50-341

NRC License No. NPF-43

2) U S NRC Inspection Report 50-341/99002,

dated March 8,1999

Subject- Reply to a Notice of Violation 99002 01

Please find enclosed Detroit Edison's response to the violation for problems

identified with three design calculations discussed in Reference 2 An extension

of the original due date for this response was granted in an April 6,1999

telephone conversation between Mr. R. Gaston (Fermi) and Mr. J. Jacobson

(Region III). The specific problems have been entered into the Corrective Action

Program. Our response describes the actions we are taking to address the

problems discussed in the Notice of Violation.

The following commitments are made by this letter:

1. The expectations for scope of calculation review when safety-related

calculations are revised will be incorporated into appropriate design

calculation review guidance by July 30,1999.

2. Revisions of Calculations DC-0230, DC-0367, and DC-5079 will be

completed by July 30,1999.

If you should have any questions, or comments concerning this reply please

contact Norman K. Peterson, Director Nuclear Licensing, at (734) 586-4258.

Sincerely ,

,

Enclosure

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APR 26 1999

("\ A DTE Energy Gmpany

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NRC 99-0017

Page 2

cc: A. J. Kugler

A. Vegel

M. V. Yudasz, Jr.

NRC Residents Office

Regional Administrator, Region III

Region III

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NRC 99-0017

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Statement of the Violation:

10 CFR 50, Appendix B, Criterion III, " Design Control," states in part,"...The ,

design control measures shall provide for verifying or checking the adequacy of I

design, such as by the performance of design reviews, by the use of altemate or

simplified calculation methods, or by the performance of a suitable testing

program. ... Design changes, including field changes, shall be subject to design

control measures commensurate with those applied to the original design."

Contrary to the above; l

A. As of January of 1999, Calculation DC-0367, " Design Calculations for RHR

System," Revision L, dated February 13,1996, incorrectly concluded that the

addition of a new low pressure coolant injection (LPCI)/ residual heat removal

(RHR) cross-tie header block valve would result in a LPCI/RHR pump head

requirement of less than 86 percent of the available pump capacity at a

calculated flow of 13,000 gallons per minute (gpm) per pump under post-

accident conditions. The calculation failed to include an applicable inputs.

The calculated LPCI/RHR pump head requirement including these inputs was

approximately 104 percent of the available pump capacity at the calculated

flow of 13,000 gpm per pump.

B. As of January of 1999, Calculation DC-0230," Core Spray System," Revision

F, addressed the test, post-accident, and run-out flow conditions of the core

spray (CS) system. This calculation sized a flow restriction orifice to prevent

the specified maximum system flow from being exceeded during run-out

conditions, and calculated the post-accident CS system flows based on this

orifice being installed in the system. However, the orifice data included in

calculation DC-0230 was not correct; this flow restriction orifice had been

resized during pre-operational testing. Due to the correction of the orifice size,

the margin between the calculated test pressure acceptance criterion and the

Technical Specification 4.5.1.b.1 value was reduced from approximately 8.5

psi to 0.1 psi.

C. As of January of 1999, Calculation DC-0885,"ECCS Suction Line Air

Ingestion," Revision B, determined the submergence at which air could

potentially be entrained in the emergency core cooling systems (ECCS) suction

lines from the suppression pool. Modification EDP-29024 replaced the ECCS

suction strainers with large strainers. Neither the calculation or the

- modification addressed the minimum suppression pool water level allowed by

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Technical Specification 3.5.3.b during operational conditions 4 and 5. The

ECCS suction strainers installed by engineering design package (EDP)-29024

would be partially uncovered with the minimum suppression pool level during

mode 4 and 5 operations.

Reason for the Violation:

The circumstances related to each of the calculation deficiencies identified in the

violation are discussed individually. While all involved personnel error, the

circumstances surrounding their occurrence was different.

Calculation DC-0367. Design Calculations for RHR System -

DC-0367 was revised in 1996 to incorporate an assessment of the impact of

the addition of a new low pressure coolant injection (LPCI)/ residual heat

removal (RHR) cross-tie header block valve. The assessment was performed

in 1994 when the engineering design package was developed to install the new

valve. The assessment was to determine that the LPCI/RHR system head

requirement with the new valve would be less than the available head

developed by the RHR pumps. Only the dynamic head loss due to frictional

effects (including the new valve) was considered. Elevation head and reactor

vessel pressure erroneously were not considered in determining the new

system head requirements. This resulted in underprediction of the LPCI/RHR

system head requirement. This deficiency in DC-0367 was the result of

personnel error.

DC-0367 was reviewed and updated in 1996 in support of a modification to

replace ECCS suction strainers in response to NRC Bulletin 96-03, " Potential

Plugging Of Emergency Core Cooling Suction Strainers By Debris In Boiling-

Water Reactors." The scope of this review focused on the hydraulic impact on

the RHR/LPCI system of the installation oflarger suction strainers, and did

not identify the error that had been made previously.

Calculation DC-0230. Core Sorav System

There are three calculations associated with the deficiency related to DC-0230

identified in the violation. DC-0230 is the major design calculation for the

core spray (CS) system. DC-204 sized restriction orifices in safety related

applications. DC-5079 documented the bases for Technical Specifications

surveillance requirements for the CS system.

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NRC 99-0017

Page 3

The system hydraulic calculations were added to DC-0230 in the early 1980s.

These hydraulic pressure drop calculations include an additional 10 psi for

margin. DC-204 sized the core spray system restricting orifices based on the

pressure drop calculated in DC-230 required to prevent pump runout. The

original orifice size determined by DC-204 was incorrect primarily because of

the 10 psi margin included in DC-230, which is non-conservative for the

pump runout evaluation.

This incorrect orifice size was discovered in 1982 during startup testing. A

smaller diameter orifice was installed based on the test results. DC-204 was

revised at that time to reflect that the orifice was sized by test. However, DC-

230 was not revised to reflect the effect on the overall CS system hydraulic

characteristics of the new orifice pressure drop associated with the smaller

orifice size. Since DC-230 includes only the orifice pressure drop calculation

and not the orifice sizing calculation, it would be difficult to detect this error,

other than when it originally occurred in 1982.

DC-5079 subsequently was completed in 1989 to document the basis for CS

system Technical Specifications surveillance test requirements. DC-5079

used the results from DC-0230 without recognizing the error that had been

made seven years before.

DC-0230 was reviewed and updated in 1996 in support of a modification to

replace ECCS suction strainers in response to NRC Bulletin 96-03, " Potential

Plugging Of Emergency Core Cooling Suction Strainers By Debris In Boiling-

Water Reactors." The scope of this review focused on the hydraulic impact on

the CS system of the installation oflarger suction strainers, and did not

identify the error that had been made previously.

Calculation DC-0885. ECCS Suction Line Air Ingestion

DC-0885, Revision B, determined the submergence at which air could

potentially be entrained in the emergency core cooling systems (ECCS)

suction lines from the suppression pool. This calculation was originally

performed in 1983 and updated in 1996 in support of a modification to replace

ECCS suction strainers in response to NRC Bulletin 96-03, " Potential

Plugging Of Emergency Core Cooling Suction Strainers By Debris In Boiling-

Water Reactors." The original calculation considered only the normal

suppression pool water level during operation for comparison with the

calculated submergence at which air entrainment potentially could occur. At

the time of the original calculation, there were no Technical Specifications.

Consequently, there were no reduced suppression pool water level operating

modes originally considered. The Technical Specifications now permit a

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NRC 99-0017

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reduced suppression pool water level when tha olant is in cold shutdown or

refueling where ECCS requirements are minimal. Reduced suppression pool

water level operating modes were not recognized or considered when the

calculation was revised in support of the ECCS suction strainer modification

since they were not included in the original calculation

The design calculation deficiencies identified above resulted from different

circumstances in each case. There is no underlying cause common to each of the

three examples. What is common is that all three of the calculations had been

reviewed or revised recently in support of plant modifications. As the resulting

changes to the calculations were considered to be minor in nature at the time of

the calculation, the opportunity was not used to question the underlying

assumptions or methodology. This resulted in two of these discrepancies not

being identified and corrected. The third problem was an error made when the

calculation was revised.

The depth of review a design calculation receives when it is revised to reflect a

design modification depends on the degree of impact that the modification is

anticipated to have on the calculation. Where plant modifications had a major

impact on a design calculation, the assigned engineers reviewed the calculation in

detail to ensure that the modification was properly addressed in the calculation. In

some cases, the calculation was completely redone. However, most design

calculation changes associated with a design modification are simple changes to

quantify and document the minor effect that the modification has on the

calculation. In these cases, only the portion of a design calculation directly

affected by a design change was reviewed. This narrow focus in the above cited

examples contributed to pre-existing errors in these calculations not being

detected by engineering personnel when the calculations were revised.

Corrective SteDS that Have Been Taken and the Results Achieved:

The calculations identified during the inspection have been reviewed to assure the

errors identified have not affected Technical Specification surveillance test

acceptance criteria. Reviews were completed during the inspection to quantify the

effects of these errors. The errors did not affect component or system operability.

Calculation DC-0885, ECCS Suction Line Air Ingestion, has been revised. The .

revision reflects reduced suppression pool water level permitted in the cold

shutdown and refueling modes of operation. Ample margin above the minimum

required submergence to prevent air entrainment exists.

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A revision to Calculation DC-0230 to correct the identified problems has been

prepared and is under review in accordance with the Fermi design calculation

procedure. A revision to Calculation DC-0367 is currently in preparation.

Design calculations for other restricting orifices in safety related systems were

reviewed for similar problems. No similar problems were identified.

A review of trend data from the corrective action program, quality assurance

audits and surveillances, and Independent Safety Engineering Group reviews over

the past two years has not indicated an adverse trend or underlying progranunatic

weakness in the area of design calculations. Although, these activities have

identified discrepancies, none of the discrepancies have resulted in safety

equipment not being able to perform specified functions.

Examples of the types of calculation deficiencies identified in this violation have

been reviewed with engineering personnel who perform and revise design

calculations to heighten awareness for these types of problems. Expectations

regarding the extent of review when calculations are revised were also

communicated including:

• Review assumptions for correctness and applicability;

e Review calculation methad for correctness of approach and

consistency with current philosophy;

• Review input from other calculations or sources for correctness; and,

e Documentation of this review in the calculation revision.

This enhanced awareness is expected to improve identification of potential

calculation deficiencies when calculations are revised.

Corrective SteDS that Will Ba Taken to Avoid Further Violations:

The expectations for scope of calculation review when safety-related calculations

are revised will be incorporated into appropriate design calculation review

guidance by July 30,1999.

Revisions of Calculations DC-0230, DC-0367, and DC-5079 will be completed

by July 30,1999.

As a matter of course, Fermi's corrective action program documents, Condition

Assessment and Resolution Documents (CARD), are trended. In addition, QA ,

Design Control audits and surveillances routinely examine design calculations.

These programs will assess the effectiveness of corrective actions taken in

response to this violation and identify any need for additional improvements.

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NRC 99-0017

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Date when full compliance will be achieved:

Full compliance will be achieved when the calculation revisions noted above are

completed by July 30,1999.

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