View source for AECM-86-0006, Forwards Technical Justification for Proposal to Delete Peak Recording Accelerographs Currently Installed on Reactor Piping Locations,Per Section 16.3.1 of Sser 6 (NUREG-0831).Response by 860228 Requested.Fee Paid

{{Adams
| number = ML20137C068
| issue date = 01/10/1986
| title = Forwards Technical Justification for Proposal to Delete Peak Recording Accelerographs Currently Installed on Reactor Piping Locations,Per Section 16.3.1 of Sser 6 (NUREG-0831).Response by 860228 Requested.Fee Paid
| author name = Dale L
| author affiliation = MISSISSIPPI POWER &amp; LIGHT CO.
| addressee name = Denton H
| addressee affiliation = NRC OFFICE OF NUCLEAR REACTOR REGULATION (NRR)
| docket = 05000416
| license number = 
| contact person = 
| case reference number = RTR-NUREG-0831, RTR-NUREG-831
| document report number = AECM-86-0006, AECM-86-6, TAC-60467, TAC-61931, NUDOCS 8601160186
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE, UTILITY TO NRC
| page count = 5
| project = TAC:60467, TAC:61931
| stage = Other
}}

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MISSISSIPPI POWER & LIGHT COMPANY
                           ]                           Helping Build Mississippi P. O. B O X 164 0. J A C K S O N, MIS SIS SIP PI 39215-1840 EulM ahliddB January 10, 1986 ZUCLE AR LICEN51NG & SAFETY DEPARTMENT U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D. C.            20555 Attention:          Mr. Harold R. Denton, Director

==Dear Mr. Denton:==

==SUBJECT:==
Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Peak Recording Accelerographs, Proposed Deletion From Design AECM-86/0006 Mississippi Power & Light Company (MP&L) committed in letter AECM-84/0307, dated May 31, 1984 to review certain aspects of the Grand Gulf Unit I seismic monitoring instrumentation system and to implement appropriate design changes by restart from the first refueling outage. The NRC Staff's review of this matter is found in Section 16.3.1 of Supplement 6 to the Safety Evaluation Report on Grand Gulf (NUP.EG-0831).
The required engineering review has been completed and concludes that the peak recording accelerographs (PRA) currently installed on reactor piping locations are not necessary and should be deleted.
The technical justification for this proposal is provided in the attachment. As discussed with the NRC Project Manager in December 1985 on this matter, MP&L requests that the NRC staff review the attached information. Following NRC staff review and concurrence, MP&L will submit the necessary changes to the plant's technical specifications to support this design change. MP&L requests NRC review and concurrence by February 28, 1986 in order to allow sufficient time to process the necessary technical specification changes prior to restart from the first refueling outage.
In accordance with 10CFR170, an application fee of $150.00 is also attached. Please advise if additional information is required.
Yours truly, 8601160186 860110 PDR E         ADOCK 05000416 PDR L. F. Dale Director JGC:vog Attachments                                                           ,, 1      [
cc:      (See Next Page)                                             {Leol Iy     g jf. 00W
                                                                                    *lI J13AECM86010701 - 1              Member Middle South Utilities System

AECM-86/0006 Page 2 cc:  Mr. O. D. Kingsley, Jr. (w/a)
Mr. T. H. Cloninger (w/a)
Mr. R..B. McGehee (w/a)
Mr. h'. S. Reynolds (w/a)
Mr. H.1L. Thomas (w/o)
                               ~
Mr.-R. C. Butcher (w/a)
Mr.' James M. Taylor, Director (w/a)
Office of Inspection & Enforcement U. S.-Nuclear' Regulatory Commission Washington..D. C. 20555 Dr.lJ. Nelson Grace, Regional Administrator (w/a)
U. S. Nuclear Regulatory Commission Region II
                       -101 Marietta St., N. W., Suite 2900 Atlanta,= Georgia ~30323 J13AECM86010701 - 2

T Attechmtnt to AECN-86/0006 Page 1 PROPOSED REMOVAL-OF PRA MOUNTED ON THE REACTOR PIPING

==Background:==

Regulatory Guide 1.12, Rev. 1, required that a total of three (3) triaxial peak recording accelerographs (PRA) be provided at one location on each of the following:
(1) A selected location on the reactor equipment; (2) A selected location on the reactor piping; (3) A selected location on Seismic Category I equipment or piping outside of the containment structure.
Furthermore, the NRC Staff requested that triaxial peak recording accelerographs be provided on reactor vessel supports and reactor piping for Grand Gulf Nuclear Station, Unit 1 (GCNS). The NRC staff review is documented in Supplement 2 to the GGNS Safety Evaluation Report, Section 3.7.4.
The operability and effectiveness of PRAs on reactor piping were discussed with the NRC during the GGNS Technical Specification Review Program. MP&L commitments to review this matter were documented in MP&L's letter AECM-84/0307, dated May 31, 1984. The NRC review of this issue is found in Supplement 6 to the SER (Section 16.3.1). This MP&L submittal and associated proposed actions are provided in fulfillment of the commitments made in AECM-84/0307.
Existing PRAs:
There are eleven (11) triaxial peak recording accelerographs provided in the CGNS 1 design. One (1) PRA is located on reactor vessel support, four (4) on various reactor piping systems, one (1) on the containment dome, one (1) on the Control Building foundation, and one (1) in the Control Room. One (1) PRA is on the Standby Diesel Generator, one (1) on the Auxiliary Building foundation, and one (1) in the SSW Pump House B.
Problems Associated With PRAs Mounted on Reactor Piping While seven (7) of the PRAs function satisfactorily, the four (4) units mounted on the reactor piping are subject to repeated failures. All four (4) were found non-functional in July, 1983, during surveillance. Again, two (2) of these were found non-functional in January,1985, during surveillance.
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Attachm:nt to AECM-86/0006 Page 2 Probable Cause of Malfunction of PRAs Mounted on Reactor Piping A PRA is a passive device capable of recording peak acceleration during a transient event. The reactor piping is subjected to various transients during startup and' normal plant operation. During these transients, the peak acceleration recorded by instruments mounted on the piping can be significantly high even though overall response of the piping system is very small. These operating transients exceed the range of PRAs mounted on the reactor piping and render them' inoperable.
Justification For Removal of PRAs Mounted On The Reactor Piping (1) Based on the surveillance testing of PRAs installed in the GGNS-1, it has been observed that PRA's mounted on the reactor piping become non-functional during system transients. The vendor (Kinemetrics) has confirmed that a passive device (PRA) is not suitable for installation on a system which is subjected to frequent transients.
(2) The peak acceleration response due to a seismic event can not be separated from the response due to the system transients. In many cases the peak predicted seismic response is less than that due to the system transients.
(3) A meaningful and conclusive evaluation of the piping response due to a seismic event cannot be performed by having a peak acceleration at a single location on the piping system.
(4) Currently there are iive (5) Triaxial Time History Accelerographs (SMA's)
                                          ~
installed in the CGNS-1. One (1) SMA is installed on the containment foundation, and one (1) on the drywell wall. Two (2) SMAs are installed outside the containment. One (1) in the SSW pump house, and one (1) on the SGTS filter train. The fifth (5th) SMA is installed on the free field. These recorders will provide reliable acceleration time history, which can be convarted to seismic response spectra. These can easily be compared with the respective GGNS design seismic spectra for post-seismic damage evaluation.
(5) A sixth (6th) SMA will be installed on a reactor piping support for the high pressure core spray system by restart from the first refueling outage
[ Operating License Condition 2.C.(7)]. This SMA will provide an acceleration time history for a reactor piping location and confirm the post-seismic evaluation for this plant equipment.
(6) There are seven (7) PRAs mounted at various locations inside and outside the containment which will provide reliable and meaningful information for post-seismic damage evaluation.
Based on above, MP&L has concluded that the PRAs mounted on the reactor piping can be deleted since they do not serve any meaningful purpose for post-seismic damage evaluation. Additionally, there are sufficient seismic instruments which will provide required information for post-seismic damage evaluation.
J13ATTC86010701 - 2

Attschr;nt to AECM-86/0006 Page 3 Following NRC staff review.and concurrence of this report, MP&L will a                   submit-the necessary changes to the technical specifications to support these design changes.
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