ML20204H757

Discusses WCNOC 990202 Proposed Rev to Response to GL 81-07, Control of Heavy Loads, for Wcgs.Rev Would Make Reactor Building Analyses Consistent with TS & Change Commitment Not to Allow Polar Crane Hook Over Open Rv.Revs Approved

ML20204H757
Person / Time
Site:	Wolf Creek
Issue date:	03/23/1999
From:	Thomas K NRC (Affiliation Not Assigned)
To:	Maynard O WOLF CREEK NUCLEAR OPERATING CORP.
References
GL-81-07, GL-81-7, TAC-MA4749, NUDOCS 9903290152
Download: ML20204H757 (3)

Text

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% ****g* /j March 23, 1999 Mr. Otto L. Maynard President and Chief Executive Officer .

Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, Kansas 66839

SUBJECT:

REVISION TO RESPONSE TO GENERIC LETTER 81-07," CONTROL OF HEAVY LOADS'- WOLF CREEK NUCLEAR GENERATING STATION (TAC NO. MA4749)

Dear Mr. Maynard:

By letter dated February 2,1999, the Wolf Creek Nuclear Opersting Corporation (WCNOC) proposed a revision to its response to Generic Letter (GL) 81-07, " Control of Heavy Loads," for the Wolf Creek Generating Station (WCGS). WCNOC proposed to (1) revise the reactor building analyses section of the response to GL 81-07 to make it consis'ent with the technical specifications (TS), and (2) change the commitment to not allow the polar crane hook over an open reactor vessel. Specifically, WCNOC proposed to revise the reactor building analyses to clarify that only one and not two residual heat removal (RHR) trains may be operable during shutdown and refueling (Modes 5 and 6) conditions. Also, WCNOC is revisir,g its procedures to require that once the reactor upper intemals have been removed and fuel is in the reactor vessel, polar crane hook travel will be prohit'ited over the open reactor vessel except during the occasional need to reverse the orientation of the crane hoists and required vessel servicing activities. Licensee evaluation of the proposed changes concluded that the changes are consistent with the guidance contained in NUREG-0612, " Control of Heavy Loads at Nuclear Power Plants." The staff's evaluation of the proposed changes is discussed below.

Revision of Reactor Buildino Analyses The reactor building analyses section of the response to GL 81-07 currently assumes that both trains of RHR will be operable in Mode 5 pursuant to the WCGS TS. However, the WCGS TS require that only one train of RHR be operable under certain conditions in Modes 5 and 6 (if the loops are filled, and secondary side watu level of at least two steam generators is >10%

of the wide range). As such, the licensee is revising the reactor building analysis and plant procedures to make them consistent with the TS on RHR operability requirements in Modes 5 and 6. In addition, the licensee is revising a commitment to allow the movement of heavy loads over the operable RHR train, except for the RHR retum line, in Modes 5 and 6.

To support this change, WCNOC evaluated the effects of a heavy load drop on the RHR system with only one train operable. The evaluation concluded that under worst case conditions, assuming no administrative controls, a rupture of the operable RHR train return line due to a heavy load drop would result in reactor coolant system (RCS) fluid draining onto the containment floor, which would cease when the fluid level reached the bottom of loop pipe level.

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. .. Mr. Otto L. Mayn:rd March 23, 1999 Under these circumstances, the licensee has concluded that other emergency core cooling l

system equipment and inventory would be available to keep the core covered and from boiling L. in accordance with plant procedures. However WCNOC is making a commitment to maintain

( administrative controls in plant procedures to prevent movement of heavy loads over the only operable RHR return line. This will ensure that the above scenario does not occur and equipment needed for safe shutdown is protected in accordance with the guidance in i NUREG-0612.

l Movement of the Crane Hook Over the Reactor Vessel j in its original response to GL 81-07, WCNOC committed to ensuring that crane hook travel j would not be allowed over an open reactor vessel once the reactor upper internals are removed, and fuel is in the reactor vessel, except during required vessel servicing activities.

The licensee is revising this commitment to state that once the upper internals have been removed and fuel is in the reactor vessel, crane hook travel will be prohibited over the open I l vessel except for the occasional need for reversing the orientation of the main / auxiliary hoists and for required vessel servicing activities. In addition, when there is fuel in the reactor vessel, administrative procedures will restrict use of the hoist controls (i.e., raising and lowering the hook) when the hook is moved over the open reactor vessel to reverse the hoist orientation.

The only item to be attached to either hoist may be the load cell linkage attached to the main hook.

To support this change, WCNOC evaluated the potential drop of the load block / hook on the open reactor vessel and concluded that such a drop is not credible because redundant and independent limit switches provided on the polar crane main and auxiliary hoists ensures that two-blocking accidents are prevented.

The staff reviewed WCNOC's revision to its response to GL 81-07 and finds the changes to be consistent with the recommended actions contained in NUREG-0612 to assure safe handling of heavy loads.

If you have any questions, please contact me at (301) 415-1362.

Sincerely, Original Signed By Kristine M. Thomas, Project Manager Project Directorate IV-2 Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-482 DISTRIBUTION:  ;

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Mr. Otto L. Maynard March 23, 1999 cc:

Jay Silberg, Esq. Chief Opers,0ing Officer Shaw, Pittman, Potts & Trowbridge Wolf Creek Nuclear Operating Corporation 2300 N Street, NW P. O. Box 411 Washington, D.C. 20037 Burlington, Kansas 66839 Regional Administrator, Region IV Supervisor Licensing U.S. Nuclear Regulatory Commission Wolf Creek Nuclear Operating Corporation 611 Ryan Plaza Drive, Suite 1000 P.O. Box 411 l Arlington, Texas 76011 Buriington, Kansas 66839

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Senior Resident inspector U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Resident inspectors Office P. O. Box 311 8201 NRC Road Burlington, Kansas 66839 Steedman, Missouri 65077-1032 Chief Engineer Utilities Division Kansas Corporation Commission 1500 SW Arrowhead Road Topeka, Kansas 66604-4027 Office of the Govemor State of Kansas

~ Topeka, Kansas 66612 Attomey Geners Judicial Center 301 S.W.10th 2nd Floor Topeka, Kansas 66612 County Clerk Coffey County Courthouse Burlington, Kansas 66839 Vick L. Cooper, Chief Radiation Control Program Kansas Dspartment of Health and Environment Bureau of Air and Radiation Forbes Field Building 283 Topeka, Kansas 66620 1

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