NRC Generic Letter 1989-22

NRC Generic Letter 1989-022: Potential for Increase Roof Loads and Plant Area Flood Runoff Depth at Licensed Nuclear Power Plants Due to Recent Change in Probable Max. Precipitation Criteria Developed by National Weather Service

ML031210438
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, 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, 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, Washington Public Power Supply System, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Clinch River, Crane
Issue date:	10/19/1989
From:	Partlow J Office of Nuclear Reactor Regulation
To:
References
NUREG-0800 GL-89-022, NUDOCS 8910180273
Download: ML031210438 (5)

UNITED STATES

t BNUCLEAR REGULATORY COMMISSION

WASHINGTON, D. C. 20555 October 19, 1989 TO: ALL LICENSEES OF OPERATING REACTORS AND HOLDERS OF CONSTRUCTION

PERMITS*

SUBJECT: POTENTIAL FOR INCREASED ROOF LOADS AND PLANT AREA FLOOD RUNOFF DEPTH

AT LICENSED NUCLEAR POWER PLANTS DUE TO RECENT CHANGE IN PROBABLE

MAXIMUM PRECIPITATION CRITERIA DEVELOPED BY THE NATIONAL WEATHER

SERVICE (GENERIC LETTER 89-22)

This letter is to inform you that the NRC staff has adopted for future plants the latest probable maximum precipitation (PMP) criteria published by the National Oceanic and Atmospheric Administration (NOAA), National Weather Service (NWS) to establish acceptable design configurations for safety-related nuclear power plant facilities. The staff has been using the PMP concept in plant flood design for well over 15 years. The criteria appear in Regulatory Guides, ANSI Standards, and Standard Review Plans (NUREG-0800) and were based primarily on procedures established in the 1940s and 1950s by the U.S. Army Corps of Engineers and National Weather Service (NWS).

Since 1977, more recent PMP criteria have been published by the National Oceanic and Atmospheric Administration (NOAA), National Weather Service.

These criteria are to be used to evaluate the degree of licensee compliance with the General Design Criterion 12 App A to 10 CFR Part 50. The new criteria are contained in NOAA/NWS Hydrometerological Reports (HMR) No. 49

(1977), No. 51 (1978), No. 52 (1982), No. 53 (1980) and No. 55 (1984). One of the more significant changes in the new HMRs is that they now provide PMP

estimates for drainage areas as small as 1 square mile and for durations as small as 5 minutes. The previous reports generally only provided PMP estimates for areas of 10 square miles or greater and durations of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> or more.

There were empirical methods to subdivide the 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> duration to smaller increments, but there was never any methodology to estimate PMP for areas less than 10 square miles. Thus, the 10 square mile PMP values were used for site and roof drainage design. Current 1 square mile short duration PMP estimates are larger than those previously used.

Staff has revised (Revision 3) Sections 2.4.2, Floods,' and 2.4.2, 'Probable Maximum Floods (PMF) on Streams and Rivers," of the Standard Review Plan (NUREG-0800) to formally incorporate the latest NWS reports into the licensing

1* Five plants, Byron, Braidwood, Vogtle, South Texas, and River Bend, fully meet the new PMP Criteria and the licensees for these five plants may dis- i letter.

91 180273t C

Generic Letter 89- 22 - 2 - October 19, 1989 review process. In general, the latest NWS criteria call for higher rainfall intensities over shorter time intervals and smaller areas than have been previously considered. In some cases, such events could result in higher site flooding levels and greater roof ponding loads than have been used in previous design studies.

This information is provided for your review and determination of appropriate action, if any. No submittal is required.

Sincerely, Jades G. Partlow Associate Director for Projects Office of Nuclear Reactor Regulation Enclosure:

List of Most Recently Issued Generic Letters

Technical Contact:

_____ _ __ _

S. Chan, ESGB/NRR

492-0830

LIST OF RECENTLY ISSUED GENERIC LETTERS<_>

Generic Date of c.. I; , 4_. 1 ciiand- T Issued To Letter NO. uu vLL ------ -

89-22 POTENTIAL FOR INCREASED ROOF 10/19/89 ALL LICENSEES OF

LOADS AND PLANT AREA FLOOD OPERATING REACTORS AND

RUNOFF DEPTH AT LICENSED HOLDERS OF CONSTRUCTION

NUCLEAR POWER PLANTS DUE TO PERMITS (EXCEPT BYRON

RECENT CHANGE IN PROBABLE BRAIDWOOD, VOGTLEO

MAXIMUM PRECIPITATION SOUTH TEXAS, AND RIVER

CRITERIA DEVELOPED BY THE BEND)

NATIONAL WEATHER SERVICE

(GENERIC LETTER 89-22)

89-21 REQUEST FOR INFORMATION 10/19/89 ALL HOLDERS OF

CONCERNING STATUS OF OPERATING LICENSES

IMPLEMENTATION OF UNRESOLVED AND CONSTRUCTION

SAFETY ISSUE (USI) REQUIREMENTS PERMITS FOR NUCLEAR

POWER REACTORS

89-20 PROTECTED AREA LONG-TERM 09/26/89 ALL FUEL CYCLE

HOUSEKEEPING FACILITY LICENSEES

WHO POSSESS, USE,

OR PROCESS FORMULA

QUANTITIES OF

STRATEGIC SPECIAL

NUCLEAR MATERIAL

89-19 REQUEST FOR ACTION RELATED TO 09/20/89 ALL LICENSEES OF

RESOLUTION OF UNRESOLVED OPERATING REACTORS,

SAFETY ISSUE A-47 "SAFETY APPLICANTS FOR

IMPLICATION OF CONTROL OPERATING LICENSES

SYSTEMS IN LWR NUCLEAR AND HOLDERS OF

POWER PLANTS" PURSUANT TO CONSTRUCTION PERMITS

10 CFR 50.54(f) FOR LIGHT WATER

REACTOR NUCLEAR

POWER PLANTS

89-18 RESOLUTION OF UNRESOLVED 09/06/89 ALL HOLDERS OF

SAFETY ISSUE A-17, "SYSTEMS OPERATING LICENSES

INTERACTIONS IN NUCLEAR OR CONSTRUCTION

POWER PLANTS PERMITS FOR NUCLEAR

POWER PLANTS

ACCESSION NUMBER IS 8909070029

89-17 PLANNED ADMINISTRATIVE 09/06/89 ALL HOLDERS OF

CHANGES TO THE NRC OPERATOR OPERATING LICENSES

LICENSING WRITTEN EXAMINA- OR CONSTRUCTION

TION PROCESS - GENERIC PERMITS FOR PWRS

LETTER 89-17 AND BWRS AND ALL

LICENSED OPERATORS

89-16 INSTALLATION OF A HARDENED 09/01/89 ALL GE PLANTS

WETWELL VENT (GENERIC

LETTER 89-16)

Generic Letter 89- 22 - 2 - October 19, 1989 review process. In general, the latest NWS criteria call for higher rainfall intensities over shorter time intervals and smaller areas than have been previously considered. In some cases, such events could result in higher site flooding levels and greater roof ponding loads than have been used in previous design studies.

This information is provided for your review and determination of appropriate action, if any. No submittal is required.

Sincerely, ORIGINAL SIGNED BY JAMES G. PARTLOW

James G. Partlow Associate Director for Projects Office of Nuclear Reactor Regulation Enclosure:

List of Most Recently Generic Letters

Technical Contact:

S. Chan, ESGB/NRR

492-0830

DISTRIBUTION:

Central Files NRC PDR I

PD4 Reading P. O'Connor 1KVIaW

It1 F. Hebdon G. Holahan F. Miraglia C. Berlinger J. Partlow

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NAME :PO'Connor:bj:FHe n :G olahan olahan  :' tw DATE_ :--------- --- /---/8- _--/89 _______/89 _ --__

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DATE :1 /X7)/89  :/2L1/89 :lf /%V /89 V'A%/89  : 8al9 M /§/89 : l 5/89 f

OFFICIAL RECORD COPY

Document Name: GENERIC LETTER/PD4

DOCUMENT NAME:

GENERIC LETTER/PD4 ORIGINATOR NAME *:

P. O'Connor x23026 SECRETARY NAME:

Beverly/Celeste x21340

SUBJECT:

GENERIC LETTER 89-XX RE: DESIGN FOR PROBATE E MAXIMUM

NAME DATE

1. P. O'Connor

2. F. Hebdon

3. G. HoIahan3tj-'CA2

_-°\ lokh

4. G. Holahan 1°c\I I\

5. F. Miraglia C. Berlinger j F/Z/7

7. J. Partlow

7. Secretary - Dispatch PLEASE DO NOT REMOVE THIS SHEET FROM PACKAGE

• CAN THIS DOCUMENT BE DELETED FROM SYSTEM? YES NO

SHOULD THIS DOCUMENT BE ARCHIVED? YES ---- NO_