L-83-399, Forwards Final Response to NRC Re Purge Valve Operability.Revised Purge Valve Rept Addresses Remaining NRC Concerns Re Operability of 48-inch Containment Purge Valves for Facility
| ML17301A047 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 07/15/1983 |
| From: | Robert E. Uhrig FLORIDA POWER & LIGHT CO. |
| To: | Clark R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17214A312 | List: |
| References | |
| L-83-399, NUDOCS 8307190160 | |
| Download: ML17301A047 (9) | |
Text
t REGULA INFORMATION DISTRIBUTI, TEM (BIDS) t ACCESSION NBR:8307190160 DOC.'.DATE: 83/07/15 NOTARIZED:
NO
~FAC'IL 50 335 St.
Luc i e P
1 ant i Uni t 1i F 1 ori da Power L Liaht Co ~
AUTH NAME AUTHOR AFFILIATION UHR I G ~ R. E.
Florida Power.,8, Liaht Co.
RECIP. JA/E RECIPIENT A~FILIATION CLARKiR A Ooeratina Reactor s Branch 3
DOCKET 05000335.
~ ~
final t'esoonse tv.Reviseg pur re ooerabilitv i ty. //
SUBJECT:
- Forwards, ooerabili concer.ns for facil DISTRIBUTION CODE A03 COPTFS TITLE:
OR Submi t ta 1: Containment to NRC 830216.
1 tr re ourae ya) ve ae valve reot, addr.esses remainina NRC of 48-inch containment ourae valves R CEIVEO:LTR '+ ENCL~~'IZE 'S+%~
Puraina NOTES
~
K~~tILt%%Asek&%%%
RECIPIENT ID CODE/NAME NRR ORB3 BC 01 COP T,ES
'EC IP IENT LTTR ENCL ID CODE/NAME 7
7 COPIES LTTR ENCL INTERNAL'RR.FIELDSiM 12 09 RFG FILE 04 1
1 1
1 1
1 NRRtREEVESiE 14 NRR/DS I/AEB RGN2 EXTERNAL: ACRS 13 NRC PDR 02 NTIS 6
6 1
1 1
1 LPDR NSIC 03 OS TOTAL 'NUMBER OF.COPIES REQUIRED:
LTTR 23 ENCL 23
P 44
~
f n Al'I't l,'
~
~
4;~
O. BOX 14000, JUNO BEACH, F L 3340B j"==
fi)r.o+
FLORIDAPOWER & LIGHTCOMPANY July 15, 1983 L-83-399 Office of Nuclear Reactor Regulation Attention:
Mr. Robert A. Clark, Chief Operating Reactors Branch N3 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D. C. 20555
Dear Mr. Clark:
Re:
St. Lucie Unit I
Docket No. 50-335 Containment Pur e Valve O erabilit This letter contains Florida Power 8 Light Company's final response to your letter of February l 6, l 983 concerning St. Lucie Unit I purge valve operability.
The Henry
~ ratt Company has completed the revised purge valve report for St. Lucie Unit I.
Enclosure I summarizes the results of the report and Enclosure 2 contains the full report.
The enclosures adequately address the remaining NRC concerns regarding the operability of the 48" containment purge valves for St. Lucie Unit I.
We trust that the information'contained in this letter will allow the NRC staff to complete their review.
Very truly yours, Robert E. Uhrig Vice President Advanced Systems and Technology REU/PKG/cab cc:
Mr. James P. O'Reilly, Region ll Harold F. Reis, Esquire I
Enclosures DOCH 05000
~
i90160 8307i5 PDR A
PDR,'
zo ~g PEOPLE... SERVING PEOPLE
yO 4
\\
. Re:
St. Lucie Unit l Docket No. 50-335 Containment Pur e Valve 0 erabilit ENCLOSURE 1
In accordance with the commitment made in our letter L-83-203 dated March 31,
- 1983, Henry Pratt has now completed the revised Containment Purge Valve Aerodynamic Torque Calculation and Stress Analysis for the St; Lucie Unit No.
1, 48" Containment Purge Valves.
This analysis has been prepared utilizing Henry Pratt's most current methodology and test data available, which are summarized below:
A.
1.
Purge valve closure time during a
LOCA was less than or equal
-to the wo-flow time demonstrated durixg shop tests, si~ce fluid dynamic effects tend to close a butterfly valve.
Valve closure rate vs.
time was based on a sinusoidal function.
2.
Flow towards the hub side of an offset asymmetric disc was assumed in the calculations as it contributed to the highest torques.
3 ~
Upstream pressures acting on the valve were determined from the containment pressure vs.
LOCA time curve for a 19.2.ft.
slot break (FSAR Fig. 6.2-7A) assuming maximum delay times and maximum valve
, closure time.,Muimum.downstream q>ressures vs LOCA.'time were assumed.
4.
A single valve closure of the inside containment valve, with the
'obtside containment valve fixed at the fully open position was determined to be worst case.
5.
Containment back pressure had no effect on cylinder operation since the same back pressure would also be present at the inlet side of the cylinder and differential pressure would be the same during operation.
6.
This analysis also assumed that the first incidence of sonic flow coincided with the critical valve disc angle as a worst case condition.
7.
In this report worst case conditions were considered; i.e.
a 90 elbow (upstream) oriented 90 out-of-plane with respect to the valve shaft and the leading edge of the disc closing toward the I>>
outer wall of elbow.
Effects of downstream piping on system back pressure are covered in. A. 3.
above.
The Pratt purge valve analysis program was developed for indicated LOCA conditions using existing Pratt model test data.
During 1982, Pratt undertook additional model testing to consider alternate valve/
piping configurations, such as the elbows immediately as well as two diameters upstream of the valve with the valve shaft "out-of-plane" with respect to the elbows, flow from the flat and arch side of the
- disc, clockwise and counterclockwise disc closure, and various disc
~.diameter to thickness ratios.
The dynamic torques determined by the model tests were in all cases lower than those calculated by 'the Pratt purge valve analysis program.
This analysis consisted of a static analysis of the valve components to determine whether the stress levels under combined seismic and LOCA conditions were less than allowable stresses and/or 0.40 x yield strergfh for shear (non-Code components) as indicated. in Table l for the materials utilized.
A valve operator evaluation was presented based on the operator manufacturer's rating versus the calculated LOCA"induced fluid dynamic torques.
P With regard to sealing integrity, decontamination chemicals have very little effect on EPT and stainless steel seats.
Molded EPT seats are generica"lly known to have a cumulative radiation resistance of 1 x 10 rads at a maximum incidence temperature of 350 F.
FPL intends to visually inspect the seats every 18 months and" replace them as required in accordance with Henry Pratt's recommendations.
Valves at outside ambient temperatures below O', i.f not properly
- adjusted, may have leakage due to thermal contraction of the elastomer;
- however, during a LOCA, the valve internal temperature would be expected
\\
to be higher than ambient which tends to increase sealing capability after valve closure.
Please note that the lowest ambient temperature recorded onsite is 28.4'F.
Valve operator capability was evaluated as follows:
Model:
Bettis T520-SR2 Rating:
200,000 in-lbs at full open and closed positions only.
143,774 in-lbs at 68'.
125,000 in"lbs at 45 (minimum rating)
Maximum calculated valve torque:
98,358 i'-lbs (valve blocked at 40 ).
The maximum torque generated during a
LOCA induced reactive forces in the load carrying components of the actuator.
Since the LOCA induced torque calculated in this analysis for valve disc opening of 40 was lower than the absorption rating of the operator, it was concluded that the Bettis model furnished was structurally suitable to withstand combined LOCA and seismic loads as defined in this analysis when blocked to a maximum opening angle of 40 from the closed position.
Please note that the design for the modification to block the purge valves at 40 open has been completed.
This modification is presently scheduled to be implemented during the present outage prior to mode 4
operation.
Based on the above considerations the analysis demonstrated that the r
calculated stresses of the valve components (for, valve blocked at 40 )
for combined seismic and LOCA conditions were less than allowable stresses and/or 0.40 x yield strength for shear (non-code components) as indicated in Table 1 of the report.
Please note that the valve component which had the smallest margin between the calculated and allowable stress was'he adjusting screw threads.
As per Table 1 of the report, the calculated shear stress is 9527 psi vs.
ASHE allowable stress level of 9960 psi. 'owever, this cal'culated value for shear stress has a much higher margin of safety when compared to 0.4 x yield strength of the material (12000 psi).
Three (3)copies of the Henry Pratt analysis for "48"-RlA Butterfly Valve Blocked at 40 " dated April 27, 1983, are enclosed for your review.
Ve believe this analysis adequately addresses the remaining concerns regarding the operability of the 48" Containment Purge Valves for St. Lucie l.
Re:
St. Lucie Unit 1 Docket No. 50-335 Containment Pur e Valve 0 erabilit ENCLOSURE 2
Henry Pratt Company Containment/Isolation Purge Valve Analysis St. Lucie
'nit 1, April 27,.1983