Information Notice 1987-56, Improper Hydraulic Control Unit Installation at BWR Plants

Improper Hydraulic Control Unit Installation at BWR Plants

ML031130489
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	11/04/1987
Revision:	0
From:	Rossi C E Office of Nuclear Reactor Regulation
To:
References
IN-87-056, NUDOCS 8710290234
Download: ML031130489 (6)

.JSSINS-No.

IN 87-566835UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555November 4, 1987NRC INFORMATION NOTICE NO. 87-56:IMPROPER HYDRAULIC CONTROL UNITINSTALLATION AT BWR PLANTS

Addressees

All holders of operating licenses or construction permits forreactors (BWRs).boiling water

Purpose

This information notice is being provided to alert addressees to a potentialproblem that could affect the ability of the hydraulic control units (HCUs)to control the positioning of the control rods in the event of an earthquake.In addition, the potential for damage to the control rod drive (CRD) systemwithdraw lines that exists under certain conditions could result in a small-break loss-of-coolant accident in the HCU area. It is expected that recipientswill review this information for applicability to their facilities and consideractions, as appropriate, to avoid similar problems. However, suggestions con-tained in this information notice do not constitute NRC requirements; therefore,no specific action or written response is required.Background:The CRD system controls the position of the control rods within the reactorcore either to change reactor core power or to rapidly shut down the reactor(scram). The HCU is a major component of the CRD system that incorporates allthe hydraulic, electrical, and pneumatic equipment necessary to move one CRDmechanism during normal or scram operations. This equipment, which includesthe accumulators, CRD insert lines, CRD withdraw lines, and scram valves, issupported by the HCU frames.If a sufficiently large number of HCU frame bolts are missing or loose, a SafeShutdown Earthquake (SSE) could result in damage affecting the ability of theCRD system to control the positioning of the control rods. In addition, damageto a CRD withdraw line could result in a small-break loss-of-coolant accidentin the area of the HCUs.

Description of Circumstances

On May 4, 1986, at the Perry Nuclear Power Plant Unit 1, a hold-down bolt on aCRD system HCU was found to be missing. Four other HCUs were observed withhold-down bolt heads not in contact with the HCU frame. On May 15, furtherinvestigation revealed that all of the HCUs had been installed with bolt torque8 7 0 9 2-3 4

IN 87-56November 4, 1987 values differing from the requirements of the seismic testing in the Environ-mental Qualification Report. Also, the upper support for each of the 16 branchjunction modules (BJMs) was erroneously attached to an HCU frame. (A BJM is anenclosure containing rod position sensor cable terminations and voltage regu-lating transformers for the Rod Control and Information System. It is mountedto one of a group of HCUs which it serves.) During installation, the BJMs wereattached to the HCUs in accordance with a General Electric Co. (GE) drawing,but the HCU seismic test configuration used for equipment qualification did notinclude a BJM.After the degraded condition of the HCUs at the Perry plant was discovered, GEissued letters to all BWR owners regarding Potentially Reportable Condition(PRC) 86-08, "Improper Hydraulic Control Unit Installation." The lettersinformed the owners of the condition of the Perry HCU units. The lettersconcluded that neither the missing or loose hold-down bolts nor the erroneousBJM attachment observed at the BWR/6 constituted a safety problem during afaulted event at that plant, nor would they at any other BWR because if theremaining hold-down bolts were snug tight, they would enable the HCU to scramthe control rods. The GE letters did not address the possibility of damage toa CR0 withdraw line that is attached to the HCU. A-ruptured CRD line wouldconstitute a small-break loss-of-coolant accident.During an inspection at Pilgrim Nuclear Power Station on March 13, 1987 (inLresponser f-o-GtEter No. G-H 2 l968Ydated Octo 86, regading improperHCU installation), Boston Edison Company (BECo) identified loose or missingbolts at the top and base of 31 of 145 HCU frames. Also, BECo found flatwashers were not installed with the base bolts, which was contrary to theinstallation drawing. The BECo engineering evaluation of the as-found condi-tions concluded that design-basis operability of the HCUs could not be estab-lished for loading conditions postulated for the SSE. BECo installed thecorrect bolting to ensure the integrity of the HCU structure.Discussion:Although the GE letter, based on the condition of the HCUs at the Perry plant,provides some assurance that a safety problem does not necessarily exist, theexperience at the Pilgrim plant demonstrates that some improperly installed HCUconfigurations might not meet seismic design criteria. The GE letter pointedout that the responsibility for implementing adequate HCU bolt hold-down torquerests with the utility and GE recommended that HCU installations be checked toensure that:1. The HCU mounting, whether with bolts or welding, is consistent with theseismic qualification test configuration. The utility may wish to usethe actual HCU seismic qualification torque value to ensure adequatetightness.2. Where BJMs are incorporated, they are not attached directly to the HCUframe above the floor, except in cases where the BJM has been consideredin the equipment qualification result AttachoentIN 87-56Novneber 4, 1987LIST Of RECENTLY ISSUEDINFOIIATION INOTICES 19t7_iyrmto .aeCInTorwaf onNotice No.'7-5407-54Sub t.tPortable Noisture/Sonsityaus Recent Incidentset Portable Oaugs BeingStolen or LostEmergency Respons Exercises87-53 Auxiliary Fedwater PUMPTrips Resulting from LouSuction Pressure87-52 Insulation Ireakdown ofSilicone Rubber-InsulatedSInglo Conductor CablesOuring 1r1gh Potential TestinrC7-51 Failure of Low PressureSafety Injection PuMP Outo seal Probles67-SO Potential LOCA at High-and Louw-Presure Interfacentrom Fire Dame07-49 Deficiencies In OutsideContainment FloodingProtection87-48 Information Concerning theUse of Anaerobic Adhesive/Sealants87-47 Transportation of Radio-fraphy DevicesIsanc Issued to10/20/87 All MRe licenseesauthorized topossess portablegauges.10/23/87 All holders of OLsor CPs for nuclearpower reactors.10/20/87 All holders of OLsor CPs for nuclearpouer reactors.10/16/B7 All holders of OLsor CPs for nuclearpower reactors.10/1O367 All nuclear powerreactor tacilitiesholding an OL or CP.IOD//87 All nuclear powerreactor facilitiesholding an OL or CP.10/9/B7 All nuclear powerreactor facilitiesholding en OL or CP.ID/I/B7 All nuclear powerreactor facilitiesholding en OL or CP.10/5/87 All NR licenseesauthorized to menu-facture, distributeand/or operate radio-graphic xpouredevices and/Orsoure changers.OL

• Operating LicenseCP

• Construction PermitUNITED STATESNUCLEAR REGULATORY COMMISSIONWASHINGTON, D.C. 20555OFFICIAL BUSINESSPENALTY FOR PRIVATE USE, *300FIRST CLASS MAILPOSTAGE 6 FEES PAIDUSNRCPERMIT NIo. 47 IN 87-56November 4, 1987Page 3 of-3No specific action or written response is required by this information notice.If you have any questions about this matter, please contact the technicalcontact listed below or the Regional Administrator of the appropriate regionaloffice.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation

Technical Contact:

Samuel MacKay, NRR(301) 492-8394

Attachment:

List of Recently Issued NRC Information Notices IN 87-56November 4, 1987 No specific action or written response is required by this information notice.If you have any questions about this matter, please contact the technicalcontact listed below or the Regional Administrator of the appropriate regionaloffice.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation

Technical Contact:

Samuel MacKay, NRR(301) 492-8394

Attachment:

List of Recently Issued NRC Information Notices*SEE PREVIOUS CONCURRENCES*OGCB:DOEA:NRR *PPMB:ARMSDMacKay TechEd09/09/87 09/11/87*C/OGCB:DOEA:NRRCHBerlinger09/09/87 I I :I -IN 87-XXSeptember xx, 987No specific action or written response is required by this information notice.If you have any questions about this matter, please contact the RegionalAdministrator of the appropriate regional office or this office.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation

Technical Contact:

Samuel MacKay, NRR(301) 492-8394

Attachment:

List of Recently Issued NRC Information NoticesOGCB:DOEA:RSDMacKayo9/9 /87PPMB:ARMTechE '091ij /$7C9C/OGCB:DOEA:NRRCHBerlinger09/9 /87D/IWOEA:NRRCERossi09/ /87