ML20197K052
Text
e
,k4 2,
fc M
b hgG o
UNITED STATES NUCLEAR REGULATORY COMMISSION o
2 I
WASHINGTON, D. C. 20555
/
$N jut, t 2190 MEMORANDUM FOR: Ashok C. Thadani, Chief Reliability and Risk Assessment Branch FROM:
Franklin D. Coffman, Leader Systems Interaction Reliability and Risk Assessment Branch
SUBJECT:
TRIP REPORT - JULY 9, 1985 AUDIT OF SYSTEMS INTERACTIONS AT DIABLO CANYON - 2
Reference:
Memorandum for A. C. Thadani, RRAB, from G. W. Knighton, LB#3, "Diablo Canyon - Request for SISI Audit," July 1, 1985.
Per the DL request documented in the reference memorandum, I visited Diablo Canyon-2 to review the specific seismically induced systems interaction postulated between the incore flux mapping system and the seal table. The specific equipment involved are inside containment.
This particular seismically inducedsystemsinteractionwasthesubjectofboththeIEInformationNotice No. 85-45 and a request for information by Commissioner Asselstine. The. seal table was postulated to be vulnerable to damage from above by seismically induced collapse of equipment in the incore flux mapping system. The interaction was postulated to lead to a break in the primary coolant system pressure boundary _
at the mechanical seals that are between the incore instrument tubes and the incore instrument tube thimbles.
I reviewed the postulated interaction by (1) auditing the specific Seismically Induced Systems Interaction Program records, the specific Design Change Notice records, and a part of Maintenance Procedure M-7.32, (2) observing the relevant equipment in Unit 2, and (3) discussing the pertinent PG&E actions with knowledgable personnel.
The details are itemized in the three enclosed tables.
The actions taken on this specific interaction were congruent with the actions taken on other interactions previously audited by NRR and Region V staff. The discovery of this specific systems interaction and the modifications that were made comply with the conservative discovery and disposition criteria in the PG&E program as approved by NRR (NUREG-0675, Supplement 11).
While at the site the other equipment that might interact with the seal table or the instrument tubes thimbles were identified for my review.
I observed the relevant equipment, audited the specific records, and examined those modifications performed under the Seismically Induced Systems Interactions Program.
Again the discovery of these interactions and their disposition d
1 JUL 2 21985 complied with the NRR approved PG&E program.
Based upon auditing the specific systems interaction of interest and other interactions postulated with equipment located in proximity to the seal table and instrument tubes thimbles, I determined that there was no evidence in the PG&E Seismically Induced Systems Interaction Program to diminish our prior conclusions that the two Diablo Canyon units can be operated safely.
Attached is a summary of the site visit requested by DL.
l
%to Frankli D. Coffman, Leader Systems Interaction Reliability and Risk Assessment Branch
Attachment:
As stated l
cc: H. Schierling M. Mendonca l
N. Anderson D. Thatcher
,a J
Table 1 Documents Audited Interaction Documentation Sheets and attachments from B-Ob-05-01-06 through B-06-05-01-28 Portions of Maintenance Procedure M-7.32 pertaining to securing the movable frame with bolts Chronology of Seismically Induced Systems Interaction Program history Design Change Notice DVC2-EM-6332 with attachments including letters identified as PGE-4743, PGE-4761, PGE-4766, PGE-4810, WP-42, &
WP-85 Table 2 Relevant Equipment Observed.
Elevation Equipment 130 ft Incore instrument drives and supports 126 ft 5 path selectors, removable floor grates, PA speaker, support gussets, bolts, welds, "A" fra:ne, lighting fixtures, handrails, ladders 112 ft Seal table and seals, incore instrument tubes, incore instrument tube thimbles, 10 path selectors, nitrogen bottle, supply fart and cooling coil, conduit support, reactor vessel level indicator 93 ft Reactor cavity sump pump tank, FCV valves 84 ft Reactor coolant drain taak, valves, reactor coolant drain tank level indicator, lighting fixture 63 ft Incore instrument tube thimbles, insulation supports, ladders 73 ft Loose parts monitoring system calibration pinger, floor grates, instrument tube thimble bracing, lighting fixture, conduit support, platforms Table 3 Personnel Contacted Marvin Mendonca, Sr. Resident Inspector
- Thierry Ross, Resident Inspector Mark Padovan, Resident Inspector Tim Polich, Resident Inspector John Arhar, PG&E Licensing
- Bill Ellis, Bechtel Project Mechanical Group
- Steven Traisman, Consultant to both the Project & NPO*
" People involved in the discussions on the specific systems interaction of interest.
- _