ML19331C991
| ML19331C991 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 06/30/1980 |
| From: | Swart F PUBLIC SERVICE CO. OF COLORADO |
| To: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| IEB-79-14, P-80194, NUDOCS 8008270030 | |
| Download: ML19331C991 (3) | |
Text
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CENTRAL FILES
,,x public service company of? ol POR:HQ LPoa 1,
12015 East 46th Avenue, Suite 440; Denver, j W NSIC June 30,1980 u
Fort St. Vrain Unit No. 1 P-80194 Mr. Karl V. Seyfrit, Director Nuclear Regulatory Commission Region IV Office of Inspection and Enforcement 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76012
Subject:
Safety Related Piping System Audit
References:
PSC Letter P-79161 dtd 8/1/79 PSC Letter P-79198 dtd 9/4/79 PSC Letter P-79238 dtd 10/15/79 PSC Letter P-79292 dtd 12/4/79 PSC Letter P-80029 dtd 2/15/80 PSC Letter P-80091 dtd 4/24/80
Dear Mr. Seyfrit:
This supplemental reply to I&E Bulletin 79-14 is to continue PSC's October 15, 1979 commitment to report in summary form discrepancies and corrective actions associated with the Fort St. Vrain seismic review pro-gram and to report the status of program progress.
To date, 510 seismic Class I isometric packages out of a total Class I population of 729 have been audited.
The total Class I isometric population has increased from the total reported in our April 23 letter by 140 isometrics as a result of inclusion of the two-inch and under piping isometrics which interact with 2 1/2 inch and above piping and 2 1/2 inch and above Class II isometrics which were either redefined as Class I in order to bound an analy-sis problem or are attached to a Class I hanger structure.
The goal to complete by December 1980 the audit phase of PSC's seismic review program and the associated field audit craft actions appears to be achievable. All sensitive system isometrics of which there are 351, have been audited thus completing the plaat review of all systems which n st re-main operable in order to protect the health and safety of the public in the event of an accident as defined in the FSAR Design Basis Accident Number One.
The remainder of the isometrics in the audit phase of PSC's IE Bulletin 79-14 are non-sensitive and are proceeding at a slower rate as a result of plant access limitations.
8408270 O'2 0 7
Mi. Kafl V. Seyfrit l
Juni30,1980 Page 2 There are currently 13 piping analysis packages in progress involving 21 Class I piping isometrics. The sensitive system analyses are being processed on a first pri-ority basis. Analysis results continue to indicate that the piping installations of Fort St. Vrain as originally designed are conservative relative to the requirements of the Final Safety-Analysts Report. The factors of conservatism between the calculated stresses and allowable stresses are at least three for normal operation in conjunction with the operating basis earthquake and five for the design basis earthquake.
For evaluating quake (DBE) pipe restraint stresses a comparison between calculated design basis earth-stresses and normal operation stress allowables is made.
If the DBE restraint stresses exceed the normal operation stress allcwables, PSC will proceed with a two step revicw:
1) the nonnal operation stresses are calculated and compared to the normal operation stress allowablesand 2) the calculated design basis earthquake stresses i
are. compared..to the ESAR maximum faulted allowable. stresses.. If. dur..ing. this compar.ison s.
between calculated stresses and allowable stresses an over stressed condition exists, PSC shall envoke the necessary Technical Specification action statement. To date, pipe restraint analysis show a. factor of conservatism greater than one when comparing cal-culated design basis earthquake st'resses with normal operation allowable stresses.
.To.date, 837 fie1d audit craft ~ actions have been initiated as a. result of piping and pipe support audits of which 675 have been completed by construction. The numerical difference between initiated craft actions and craft actions completed by construction
. reflects the review, approval and construction process required by the. seismic program
' procedures. The-most comen--types. of. corrective actions ~ required dur.ing the.: program. to.
.2
, date have bee'n:
Remove undocumented attachments from.the hanger structure.
~
Modif'ication of "U"-bolts.
Restoration of hanger structures to intended configuration.
Table 1 contains.a detailed tabulation of discrepancies identified with audit phase of our program since our letter of April 23, 1980. The types of corrective actions listed in Table 1 are the same as reported in our April 23, 1980 program status reports with no significant distribution variations.. The majority of these corrective actions' l
continue to be within the AISC portion of the ha'nger structure.
If, during the document review and analysis conformation process, a system impair-ment is identified, PSC will follow the necessary Technical Specification action state-ments.
If there are any questions, please contact this office.
s.4 /"//
Very truly yours, Frederic E. Swart Nuclear Project Manager FES/LMM/vw Attachment i
'Mr,. Karl V. Styfrit June 30, 1980 Attachment I TABLE I
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CORRECTIVE ACTION
SUMMARY
A~pH1 14 to June 13, 1980 Discrepancy Type Percent
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1.
. Repair structural welds
~
14%.
2,
. Remove un.do.cumented att.achm.e,nt fr.om hanger. structu..r.e.s.
22.%.
~
3.
Shim plat'es - minor item incorporated into item 5
.4..
Modify U-bolts.
. ~.
1.4%
U-bolt adjustment 5%
5.
.g......... ;.v. c.~....;....:,c. :.... p... &.... :;. n.,.. -.... y.,. e
- _..g..,.,. :........
y.,
,6.
R.est, ore han'ger.' structures. to fritended configuration 22%,
0%
7.
Install. lugs and clips
- 8.
- Add nuts and' washers.and' tigh-ten loose h'ardware 17%-
9.
Install new hanger 4%
10.
Install clamps 1%
11.
Ch'ange anchor bolts 2%
.,s...
- ....... i :..v
' Frequency of occurrence of a descrepancy type as e percentage of total discrepanicies identified.
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