ML20245J445
| ML20245J445 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/28/1989 |
| From: | Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 89-206B, NUDOCS 8905040130 | |
| Download: ML20245J445 (11) | |
Text
E VINGINIA ELECTRIC AND POWEN COMI%NY HICIIMOND,VIRGINI A 20261 "M*;,C^"l,i""l" April 28, 1989-NuctaAm U. S. Nuclear Regulatory Commission Serial No.
89-206B Attention:
Document Control Desk N0/SEC-LIC:RCC: hts:4184 Washington, DC 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 SAFETY SYSTEM OUTAGE MODIFICATION TEPECTIONS SIGNIFICANT ITEM STATUS In your letter of March 17, 1989, you characterized four findings of the Safety System Outage Modification Inspecta (SS0MI) as " safety significant matters" which you requested that Virginia _lectric and Power Company address in an expeditious manner.
We provided our response to these items in our letter of March 31, 1989 (Serial No.89-206).
During a follow-up inspection conducted the week of April 3 through 7, 1989, ycu requested further clarification of safety significant item 3 to which we provided a separate response dated April 13, 1989 (Letter Serial No. 89-206A).
j This letter will provide status for items 1 through 4 in addition to i
responding to questions received during a teleconference with your staff on April 12,1989 for item #1 (see attachment).
SSOMI issues as addressed in this letter associated with startup, as wcl1 as in letter Serial No. 89-206A (Item #3), will be completed before entering Mode 4.
SS0M1 issues for North Anna Power Station Unit I will be addressed separately prior to its returning to power.
If you have further questions or require additional information, please contact us immediately.
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U.S. Nuclear Regulatory Commission 101 Marietta Street, N.W.
Suite 2900 Atlanta, GA 30323 Mr. J. L. Caldwell NRC Senior Resident Inspector North Anna Power Station i
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4 SUPPLEMENTAL RESPONSE AND STATUS OF SSONI SAFETY SIGNIFICANT ISSUES Virginia Electric and Power Company I
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ITEM 1 The inspection team identified that the service water system spray and bypass valve motor actuators were sized for an incorrect differential pressure rating of 50 psi.
In addition, the corresponding torque switch settings for the actuators were also based on the 50 psi differential pressure rating.
This calls into question the ability of this safety system to operate if called on to function.
VEPC0 was requested to verify the correct differential pressure rating for these valves and make any changes necessary to ensure the actuators would deliver the required torque under all postulated design basis conditions.
I.
STATUS OF SSOH1 ITEM #1 The Service Water System Spray Array M0V's torque switch settings were adjusted under station work order numbers 089431 and 089432 to a setting of 2.5 (to open). The valve manufacturer indicated that at this setting the MOV's will provide adequate torque to operate under design basis conditions.
Upon further review, by VEPC0 Engineering, it was determined that a more conservative approach adopted for other quarter turn valves on the Servi e Water System was appropriate for setting the torque on these valves.
Therefore, the Spray Array MC7 torque switches will be reset to a value of 5.0 (to open and to close) and the Setpoint Document will be revised and approved by SNSOC to reflect this setting prior to entering Mode 4.
The Service Water Bypass Valves are currently under administrative control to prevent operation from a throttled position.
This is being controlled by an entry in the Technical Specification Action Statement Log maintained in the Control Room. Work is now in progress to procure and install heavier spring packs for these valves.
These heavier spring packs will permit the Bypass M0V's to develop sufficient torque to operate under throttled conditions when the torque switches have been reset to take advantage of the spring pack modification.
It is currently anticipated that the installation of the heavier spring packs will be accomplished at the first maintenance opportunity after restart of the units. This is primarily due to the lead time requirements involved in procuring the heavier spring packs.
The current
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. administrative'e controls assure that.these M0V's will meet design basis operatibnalrequirements.:
4 The procurement specification for the Service Water Spray Array and
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Bypass Valves, NAS-2018, has' been revised to indicate the correct design differential l pressure rating.
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RESPONSE TO ADDITIONAL QUESTIONS, SSOMI ITEM #1 i
During' a teleconference with members 'of your staff on April 13, 1989, additional. questions were received regarding the measures that VEPCO
'has taken to identify and resolve deficiencies involving the specified pressure differential and the resulting' concerns involving M0V's on other safety-related systems at North Anna Power Station.
The questions were specifically directed at those design changes which had required a change in M0V's.
The response to this question follows:
A. review of our files was conducted to identify Design' Changes and-1 Engineering Work Requests which replaced or modified M0V's.
The listing of. North Anna Specifications was also reviewed to identify new-MOV specifications.
The review revealed four new specifications for safety-related motor j
operated valves:
NAS-2005, NAS-2018, NAS-2087 and NAS-2088.
Of these four specifications, NAS-2005 and NAS-2018 we,e identified as resulting in the installation of new motor operated valves.
NAS-2018 specified the Service Water Spray Array and Bypass M0V's which were reviewed by the SS0MI team.
The pressure differential utilized in the Service
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Water M0V Specification, NAS 2018, was the maximum operating pressure l
differential rather than the maximum design pressure differential.
Corrections regarding pressure differential and M0V capability have l
been made to this specification.
The other specification, NAS-2005, specified rising stem gate valves for suction isolation of the Outside Recirculation Spray Pumps.
The design pressure differential specified for this application was 60 psi.
This value has been reviewed and found to be conservative.
Setpoint change number SP-85-22 revised the torque switch settings to reflect the torque requirements of the MOV's specified in NAS-2005.
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.In -addition to the valves which have be n procured using new
. specifications, two' Unit 2 valves were identified that were-replaced to.
the' requirements of the original specifications.
N se valves, l-MOV-2867A and M0V-22898, were reviewed and found to confobei.to or to L
exceed the requirements of the original specifications.
Unit 2 design changes involving only motor operator modifications' - were also reviewed and the subsequent MOVATS' testing of these valves has verified their ability to-provide adequate torque to meet design requirements.
Our review of'M0V's replaced or modified by the design change or EWR-processes' is complete for North Anna Unit 2 and has confirmed the
' adequacy of these valves to meet design pressure differential and-torque requirernents. The Unit I review of the replacement MOV's is'in
< ; progress'and has revealed no deficiencies in the specified pressure
~ differential 'or torque. This effort will be concluded and you will be advised.of the results prior to Unit i restart.
MOVATS. testing was prioritized for implementation as follows:
(1).
I.E.
Bulletin 85-03 valves.
These valves were tested and the results reported in the VEPC0 response to the I.
E.
Bulletin.
(2)
Valves with a history of maintenance or operability concerns based on station records. The testing of valves identified in this category is complete.
.(3) The remaining' rising stem M0V's. The testing of these valves is ongoing.
'It should be noted that butterfly valves and other quarter-turn valves were initially excluded from the M0 VATS testing program because proven technology was not available. This test equipment is now available and is being evaluated for integration into the Noith Anna MOV program.
The M0 VATS testing to date has included approximately 70 percent of j
rising stem safety-related valves at North Anna, and there have been no I
instances where the motor operators have been determined to be l
undersized. At the conclusion of the testing of each valve, torque switches have been verified to be set in accordance with the design basis methodology.
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VEPC0 concludes, based on the reviews of specifications-issued to support design changes <and the results of the ongoing North Anna Safety-Related M0V Program, that the pressure differentials specified were appropriate and the - motor ' operated valves are operable.
This conclusion extends to the safety-related systems affected by design change modifications, as well as the other systems covered by the North Anna MOV Program.
ITEM 2 As a result of the inspection team's identification of various unjustified assumptions and omissions in setpoint calculations, the team became concerned that a controlled methodology for performing setpoint calculations did not exist.
To provide assurance that no safety system setting limits had been inadvertently compromised as a result of design changes implemented since the plant was licensed, the inspection team requested that a specific sample of 10 setpoint calculations be verified, including proper consideration of instrument span, drift value, cable accuracy and measuring / test equipment accuracy. Also, VEPC0 was requested to report any reduction in safety margin identified as a result of this verification.
STATUS OF SS0MI ITEM #2 l
During a follow-up inspection of SS0MI findings the week of April 3 through 7, 1989, wa provided Mr.
Larry Mellen of your staff with five, preliminary setpoint calculations for Unit 2.
Mr.
Mellen reviewed the preliminary calculations and found the results to be satisfactory.
At the exit meeting of your SS0MI follow-up inspection, Mr. Mellen requested that VEPC0 provide preliminary findings on the remaining five setpoint calculations.
During a telecon on. April 12, 1989, the preliminary results of the remaining five setpoint calculations were givea.
These calculations are now final.
In the calculations where a safety limit is required, the setpoints had a demonstrable margin of safety.
A finalized setpoint calculation and safety margin conclusion will be provided by May 15, 1989, and fontarded to you.
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ITEM 3 1
0 The inspection team identified that non-Class 1E pressure transmitters for the
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service water system were powered from a Class IE vital power source, without j
proper isolation.
Virginia Electric and Power Company was requested to justify or correct the specific service water instrumentation as well as evaluate other possible instances of improper isolation elsewhere in the facility.
STATUS OF SS0MI ITEM #3 In our letter dated April 13, 1989 (Serial #89-206A), VEPC0 made four (4) commitments associated with Item #3.
A status of the four commitments is as follows:
1.
Qualified Class 1E isolator cards have been installed and tested for the specific Service Water modification (DCP 84-43).
A Technical Review is in progress and will be completed prior to Mode 4 operation to close the issue.
2.
To ensure no other new circuits have a similar deficiency, we will review applicable design change packages (DCP's) and engineering work requests (EWR's) implemented sir.ce NAS-3012 was issued (April 1987).
This review will verify the proper isolation of these circuits and their adherence to the isolation design requirements of NAS-3012.
The review will be conducted in two stages for each unit.
For the first stage, DCPs and backlogged EWRs being implemented during the current outage will be reviewed and any appropriate changes made prior to entering Mode 4.
No additional discrepancies have been found to date.
Secondly, the DCPs and EWRs implemented prior to this outage, but after April 1987, will be reviewed by November 1, 1989. T>acklogged EWRs not being implemented this outage will be reviewed prior to being installed and declared operable.
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NAS-3012 will be revised to distinguish between the isolation requirements of the original plant design and the isolation requirements of new designs.
This revision will be issued by August 15, 1989.
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Individuals responsible for implementing the requirements of NAS-3012
.will be trained on'the new revision discussed in Item 3 above, per the training requirements of Section 7.4.3 of Standard EE-011, Rev. 3,
" Electrical Engineering Personnel Indoctrination and Training."
This training will be completed by September 15, 1989.
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n ITEM 4 The inspection team noted that design change packages (DCPs) did not explicitly prescribed the necessary testing required to demonstrate functionality of the system and affected components following the change. VEPC0 has committed to update the associated procedures to ensure that the required testing would be accomplished for future modifications.
To insure that the modifications being installed during the current outage are functionally tested subsequent to the installation and to ensure that the capability of the affected systems to mitigate the design basis accidents has not been compromised, VEPC0 was requested to incorporate the specific post-modification testing requirements into the design change packages or engineering work request scheduled to be installed for this outage.
STATUS OF SSOMI ITEM #4
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As discussed with members of your staff during a SSOMI follow-up inspection conducted the week of April 3 through 7,1989, and as statcd in ~our letter Serial No.89-206 dated March 31, 1989, Design Change Packages (DCPs) and Engineering Work Request (EWRs) being implemented during the 1989 refueling outages that affect system performance are being reviewed to insure that the testing criteria as stated in the letter have been met.
Also, procedures I
governing DCP and EWR preparation have been revised to assure adequate functional testing for the modification and affected systems is addressed.
Currently, Unit 2 DCP's, to be installed during this outage, have been reviewed and appropriate changes made where necessa ry.
The review of an EWR's implemented during this outage will be completed prior to entering Mode 4.
Unit 1 reviews are in progress, and will be completed prior to entering Mode 4.
Backlogged EWR's and DCP's that are approved and awaiting implementation, but not yet scheduled will be reviewed prior to their implementation and being I
declared operable..
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