05000282/LER-1997-001, :on 970108,auxiliary Building Crane Protective Features Defeated by Wiring Errors.Caused by Wiring Change for New Transmitter critical/non-critical Key Switch. Controllers Being Made to Agree W/One Another

:on 970108,auxiliary Building Crane Protective Features Defeated by Wiring Errors.Caused by Wiring Change for New Transmitter critical/non-critical Key Switch. Controllers Being Made to Agree W/One Another

ML20138J856
Person / Time
Site:	Prairie Island
Issue date:	02/07/1997
From:	Leveille J, Sorensen J NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-97-001, LER-97-1, NUDOCS 9702130255
Download: ML20138J856 (9)

LER-1997-001, on 970108,auxiliary Building Crane Protective Features Defeated by Wiring Errors.Caused by Wiring Change for New Transmitter critical/non-critical Key Switch. Controllers Being Made to Agree W/One Another

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
2821997001R00 - NRC Website

text

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Northern States Power Company Prairie Island Nuclear Generating Plant 1717 Wakonade Dr. East Welch, Minnesota 55089 February 7,1997 10 CFR Part 50 Section 50.73 U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Auxiliary Building Crane Protective Features Defeated by Wiring Errors The Licensee Event Report for this occurrence is attached. in the report, we made new NRC commitments which are italicized statements in the Corrective Action section.

This event was reported via the Emergency Notification System in accordance with 10 CFR Part 50, Section 50.72, on January 8,1997. Please contact us if you require additional information related to this event.

Joel P Sorensen Plant Manager Prairie Island Nuclear Generating Plant (g

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Regional Administrator - Region Ill, NRC

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NRR Project Manager, NRC Senior Resident inspector, NRC Kris Sanda, State of Minnesota Attachment 9702130255 970207 PDR ADOCK 05000282 S

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On January 8,1997 it was determined that the 125 ton Auxiliary Building. Crane had been used to handle a spent fuel cask while two protective features had been defeated by winng errors. A new radio control transmitter had been procured and placed in service. The controller has entical and non-critical positions which are chosen by the crane operator. The new controller was wired differently than the old one and choosing the criticaf position actually put the controller in the non-critical position. When this was done, tha main hoist drum overspeed protection was defeated as was the spent fuel 3ool roof slot limit switch.

However, some overspeed protection remained functional, roof slot alignment ights were functional, and tha crane still met the single failure proof criteria.

The controllers are being made to agree with one another and procedures are being changed to provide additional assurance that the controller is in the correct position.

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EVENT DESCRIPTION

On Januery 8,1997, Northern States Power Company's Prairie Island Nuclear Generating Plant made a ons-hour, non-emergency event notification regarding the operating mode of the Auxiliary Building's 125 ton bridge crane.

Th3125 ton Auxiliary Building crane is designed to meet the single-failure-proof guidelines of Section 5.1.6 of NUREG-0612, " Control of Heavy Loads at Nuclear Power Plants". Following recent heavy load lifts using the auxiliary building crane, a switch on the radio transmitter was discovered to be wired such that two protective features on the crane were defeated. The two features are:

Main Hoist Drum Overspeed Spent Fuel Pool Roof Slot Limit Switch This event is limited to the 125 ton Auxiliary Building crane's main hoist. The crane's trolley and hoists w:re manufactured by Ederer, Incorporated. The crane was upgraded to meet the single-failure-proof critaria of NUREG-0612 in 1992. The event occurred on 1/7/97 during the movement of a TN-40 spent fu:1 storage cask. The cask (#06) was being transferred from the spent fuel pool to the decon area of ths Auxiliary Building. After placing the cask in the decon area, the TN-40 lift beam was removed from tha main hoist and placed on its storage stand.

Upon completion of the above sequence, project engineering pemnnel noted the speed of the crane's mein hoist seemed slow in the non-critical mode of operation. Examination by project personnel and ths crane operator determined tne loaded cask had been moved in the non-critical mode of operation during the transfer from the spent fuel pool to the decon area.

During the month leading up to handling cask #06, a spare (new) radio control transmitter was purchased by NSP and placed in service. During certain crane operations when handling TN-40 casks, tha crane operator is required to turn the key switch on the radio control transmitter to the critical position prior to handling the cask.

Tha crane operator performed the procedure steps, as written, and an independent verification was psrformed each time. The crane operator and the independent verifier were unaware that when the key was tumed toward the critical position, as aligned with the label below the key switch, the crane's main hoist was actually placed in the non-critical mode. This is opposite of the effect of tuming the key towards the critical position, as aligned with the label below the key switch, on the original (old) radio control transmitter. Labeling on the outside of the new and old radio transmitters were identical.

Ths switch function is the same for either the old or new transmitter. That is, the switch still actuates the protective features required during the critical mode. Only the key position in relation to the selected Inc FORel 308A M99

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mode differs between the old and new transmitter. The key position and mode of operation is shown below:

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Old Transmitter:

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i critical non-critical critical non-critical i

l Tumbler Position - as shown Tumbler Position - as shown i

Key - removed Key -locked in tumbler j

Mode - non-critical Mode - critical N:w Transmitter:

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critical non-critical critical non-critical i

i Tumbler Position - as shown Tumbler Position - as shown Key - removed Key -locked in tumbler Mode - critical Mode - non-critical Crane operators had been trained with the old radio transmitter. Their training and experience, along with cesk handling procedures, indicated that the switch key was required to place the crane in critical, cnd the key would remain locked in the transmitter's switch tumbler while in critical mode. With the new rcdio control transmitter, this same position actually placed the crane's main hoist in the non-critical memu nu M es i

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mode. There was no additional feedback to the crane operator of the crane's mode of operation other thrn key position.

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With the crane's new radio control transmitter actually placed in the non-critical mode of operation, the two protective features mentioned earlier were not enabled during cask handling operations on 1/7/97.

i It is also realistic to assume that the crane was inadvertently in the non-critical mode during the pl cement of the empty cask #06 in the spent fuel pool on 1/6/97. Since the new radio transmitter was i

not in service for any previous cask, this event is limited tc the handling of cask #06 for the two days listad above.

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CAUSE OF THE EVENT

j Tha new radio transmitter was needed as no spare for the Auxiliary Building crane was ever procured cnd the old transmitter was suspected of causing intermittent stopping of crana motion when in service.

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The old radio control system was supplied to Ederer, incorporated by Telemotive. The new transmitter was purchased by NSP from Telemotive, referencing the original Telemotive job order number. The new transmitter was tested upon receipt for several days to determine if it corrected the intermittent j

stopping of motion problem. Testing of each individual function was not specified during receipt cctivities. Work was completed on 11/27/96, and the new transmitter placed in service.

During the annual preventative maintenance procedure, all functions of the new transmitter were tested, however, the reversed operation of the critical /non-critical selector switch was misinterpreted as correct.

Th:t is, the expected results for critical operation were obtained when the switch was in non-critical.

I Conversely, the two protective features were defeated when the switch was in critical.

i A change in the wiring for the new transmitter's critical /non-critical key switch created the opposite i

convention from the old transmitter. Telemotive's transmitter wiring drawing had been revised (on 9/13/95) since the originaljob order placed by Ederer. The differing switch configuration was not idsntified during receipt activities at NSP. Additionally, the NSP purchase crder for the spare transmitter l

was issued as QA Class ill and referenced the originaljob order number between Ederer and j

Telemotive. The transmitter drawing number or revision was not referenced because NSP did not have this information. Neither the crane nor radio control technical manuals contained the subject drawing.

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ANALYSIS OF EVENT

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NSP reviewed the original purchase order specification for the Auxiliary Building crane, both the crane and radio control technical manuals and associated drawings. Only the function of the critical /non-i critical selector switch is shown, described or discussed. The switch function is the same for either the old or new transmitter.

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A review of the drum overspeed and slot limit switch is presented below:

Drum Overspeed:

Edsrer, Incorporated was commissioned to interpret their Topical Report, EDR-1, for compliance with section 5.1.6 of NUREG-0612 when the crane is operated in the non-critical mode. Ederer's analysis notes the following:

1.

NUREG-0612 references NUREG-0554, " Single Failure Proof Cranes for Nuclear Power Plants",

compliance for crane modifications, such as this project. Ederer meets NUREG-0554 via Topical Report EDR-1, which was the primary design basis for the Prairie Island Auxiliary Building Crane.

2.

The Auxiliary Building Crane's design does not allow a load drop as a result of a single failure in either critical or non-critical mode.

3.

The crane's mechanical systems operate the same in either critical or non-critical mode.

4.

The crane's electrical systems, relevant to the Topical Report, operate the same in either critical or non-critical mode, with the following exceptions:

a.

The overspeed circuit logic is different from critical to non-critical mode. This difference is not contrary to the Topical Report.

b.

In the non-critical speed, overspeed is detected at a higher set point, allowing higher speed hoist operation. However, detection of overspeed and safe load stopping are within design parameters. This difference is not contrary to the Topical Report.

c.

In the non-critical mode, the monitoring system does not report overspeed to the crane operator. This difference is contrary to the Topical Report.

d.

In the non-critical mode, overspeed reset is automatic and does not require a reset key.

i This difference is contrary to the Topical Report.

Roof Slot Limit Switch:

The NRC's review of Ederer's Topical Repost, dated August 26,1983, evaluated the conformance with NUREG-0554. NSP had referenced the Topical Report in earlier licensing submittals, and submitted the required plant specific information requested in Appendices B&C of the Report. This submittal was m de on 2/3/92.

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Tha Appendix B supplement to EDR-1 requested the following information applicable to Section Ill.C of the Topical Report Whether interlocks are recommended by Regulatory Guide 1.13 to prevent trolley and bridge movements while fuel elements are being lifted and whether they are provided for this application.

Tha Prairie Island plant specific response is below:

The crane will not be used to lift fuel elements from the reactor core or spent fuel racks. Therefore, interlocks to prevent trolley and bridge movements while hoisting have not been provided.

Ths above response constitutes Prairie Island licensing basis for the Auxiliary Building crane regarding int:rlocks. This position was reviewed and accepted under the NRC SER related to PI license cmendment numbers 99 (Unit 1) and 92 (Unit 2) dated July 9,1992.

During the final design phase of the crane, NSP requested Ederer to provide a trolley limit switch when the main hoist is operated in the spent fuel pool enclosure. The addition of this feature was considered prudent when handling critical loads in the spent fuel pool. Section 10.2.1.2.2 -(f.12) of the Prairie Island Updated Safety Analysis Report discusses this design feature.

Limit switches have been added to the area of the slot in the roof of the fuel pool enclosure.

These limits protect the wire rope by restricting movement of the trolley while operating the main hoist in the slot area.

This design feature is not active when the crane is in non-critical mode. This feature was not challenged during the cask handling operations. The alignment lights (available to the crane operator) used to indicate the trolley's alignment with the center of the slot functioned properly. No trolley movements were required or performed during the evolution when the main hoist was operated in the slot region. The crane operator is aware of the restrictions when operating in the slot area and no trolley movements were required during the handling of cask #06.

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Per the above discussion, since:

l overspeed protection was still provided, the roof slot alignment lights were functional, and e

and the auxiliary building crane main hoist continued to meet the single failure-proof criteria, j

it can be concluded that health and safety of the public were not affected.

Since operating in the non-critical mode while handling cask #06 is considered to have been in "a condition that is outside the design basis of the plant", this is a reportable event under 10CFR50.73(a)(2)(ii)(B).

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CORRECTIVE ACTION

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The configuration of the new transmitter switch will be incorporated into the old transmitter. The new l

configuration is an improvement since the key is not required to operate in the critical mode. The new tninsmitter will be used as is.

I All functions of the new radio transmitter have been functionally tested. Satisfactory results were j

obtained and the work completed on 1/9/97.

t The Telemotive wiring drawing has been received by NSP and tal be incorporated in the technical manual for the transmitter. The current revision agrees wdh the new transmitter.

TN-40 cask handling procedures and Prairie Island heavy load procedures are in the process of being revised. Notes are added to describe the newlabeling and key function on the transmitterbox. The procedure will also be revised to check the slot limit switch function prior to criticallifts in the future.

This will provide assurance to the crane operator that the critical mode is active.

The new labels will no longer require the key position to be used when determining the crane's op:: rating mode. The label will identify the selector switch and describe the key's interface with the lock tumbler. Wording such as shown below will be added:

Critical-key removed Non-critical-key in and locked i

Training on the new switch configuration has been provided to crane riggers and operators.

Maintenance supervision has been trained on the use of the selector switch key. The key will continue to be managed under maintenance supervision. In the future, the key will only be required to place the crane in the non-critical mode.

NRC FORM 346A 1499

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senc Tosas 366A U.s. 3rocLEAR REocLAToRY CosetIsszoM 1499 LICENSEE EVENT REPORT (LER)

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Th3 purcnase of the transmitteris continuing to be reviewed. Any additionalrecommendations of the procurement or QA status will be incorporated, as needed.

FAILED COMPONENT IDENTIFICATION None l

PREVIOUS SIMILAR EVENTS

Th:re have been no similar events reported.

IslC FORM 366Al499