ML20058C473
| ML20058C473 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 07/22/1982 |
| From: | Bordine T CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20058C478 | List: |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.D.1, TASK-TM NUDOCS 8207260358 | |
| Download: ML20058C473 (3) | |
Text
- r
'w, Consumers Power Company s
Genere! Offices: 1945 West Parnall Road, Jackson, MI 49201 * (517) 788-o550 July 22, 1982
/
J
.~
/
i
~
Dennis M Crutchfield, Chief
~
T' a
Operating Reactors Branch No 5 Z",
Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555c
~ ~,
m DOCKET 50-155 - LICENSE DPR -
~%
BIG ROCK POINT < PLANT.- NUREG-0737
\\
ITEM II.D.1, PERFORMANCE TESTING OF BWR RELIEF AND SAFETY VALVES
- ]
j,.
The enclosed report is provided in response' to NUREG-0737, Item II.D.1, Performance Testing of BWR Relief and Safety Valves as identified in our letter of October 1, 1381. Our response committed,a final summary report to be submitted to include confirrietion that e,he tests performed at Wyle Labora-tories are indeed valid fd the Pig Rock Point safety valves. The Crosby Valve and Gage Company report provides this confirmation by comparison of the safety valve assembly instilled at Dairyland Power with the safety valve assembly installed at Big Rock Point. The comparison addressed valve orifice areas, materials, internals," set pressures, springs and differences in design features that'could cause a difference in valve performance.
)
Excepting spring range selection;- the Crosby report concludes that the~ control areas of the' valves are identical and, material differences do not affect performance for similar operating and installation conditions. Photographs of the test, installation were provided with our October"1, 1981 submittal to
)
confirm the similarities between Big Rock Point Plant.and the test.
In accordance wit.h the conclusions and recommendations of the report, Consumers Power Company' Vill replace the existing relief v51ve springs - #1673, with springs #1672 durink, the next outage of' sufficient duration and for which necessary' parts can bc obtaine,d. *The valves will be set according to Crosbyf.,
recommended nozzle ring and guide ring settings as per section 5.2 of the.
Report No 3983.
Consumers Power Company has evaluated interim operability of the relief valves with the existing springs. The evaluation includes a description of the cause of the occurance, identification of parameters specified in the Final Hazards Summary Report (FHSR) and the Technical Specifications and assurance that the functional requirements of affected systems are maintained. The evaluation J
oc0782-0012a142 g
8207260358 820722
.)
l PDR ADOCK 05000155 p
FDR t
l D M Crutchfield, Chief 2
Big Rock Point Plant
_ NUREG-0737 Item II.D.1 July 22, 1982 L
~
provides our justification for interim operation and is included for your 2
information.
Big Rock Point initially operated at a nominal pressure of approximately 1000 psia with relief valve set pressures of 1237-1288 psig. The ultimate rating of the plant was specified for operation at 1500 psig with safety valve set pressures approximately 200 psi higher.
The replacement springs were pur-chased in 1962 and subsequently installed to permit operation with the higher valve set pressure.
When the AEC demonstration program was finished in 1964, an optimum nominal operating pressure of 1350 psig was selected with the relief valves set approximately 200 psi higher. The existing springs, #1673 were adjusted to accommodate the new set pressure without consideration to the vendor recommended spring range.
Discussions with the chief engineer, Crosby Valve and Gage Company indicate that in its present condition with the oversized spring, the valve may achieve slightly less than full lift upon actuation at the set pressure and may expe-rience some chatter on closure. The valve manufacturer has concurred with our conclusion that while performance would not be optimal, the valves can be expected to open and reclose as required to satisfy their safety function.
These design requirements are specified via our Technical Specification and Final Hazards Summary Report (FHSR).
Section 4.1.2(a) of the BRP Technical Specifications provides the following safety relief valve description:
Number 6
Maximum Setting of First Valve 1700 Including Rupture Disc, Psia Sequential Pressure Increment 10 Setting of Remaining Valves, Psi 5
Minimum Capacity per valve 2.36 x 10 Valve Orifice Area, Square Inch 3.976 Section 4.1.2(b) establishes the following operating requirements:
"The safety relief valves shall be set appropriately for all planned reactor operating pressures so that the allowable pressure of 1870 psia (1700 plus 10%) in the nuclear steam supply system is not exceeded." Section 5.5 of the FHSR also specifies the requirement.
Section 12.5.8 of the THSR postulates an accident of coincident steam shut off with failure to scram to establish the size and settings of the safety relief valves. The setting of the first safety valve was varied from 155 psi to 250 psi through computer analyses. The analysis indicates that the six steam drum i
safety valves have a total capacity of nearly twice the normal steaming rate at a 200 psi differential set pressure.
oc0782-0012a142 i
D M..Crutchfield, Chief 3
Big Rock Point Plant NUREG-0737 Item II.D.1 July 22, 1982 It should be noted that full valve lift is not to be expected during any anti-cipated operational transient at Big Rock Point. Calculations have shown that the first relief valve will not lift for several minutes following reactor scram, and that a relief valve will only lift if the emergency condensor fails to operate. At the point of opening, the rate of pressure rise is expected to be so small that only one of the six valves (each of which has a rated capac-ity of approximately 35% of normal steaming rate) is more than adequate for relieving system pressure.
In addition, the analyzed worst case event, the Anticipated Transient Without Scram (ATWS), establishes relief capacities that are equivalent to full lift of approximately four of the six valves.
Any reduction of relief capacity at the set pressure resulting from the utilization of the stiffer spring is therefore considered inconsequential.
Furthermore, since the spring range of the existing spring #1673 is from 1631 to 1804 psig, full lift will occur upon increasing pressure so that the allowable pressure of 1870 psia will not be exceeded.
In addition to capacity, reliability of the relief valves to actuate at or near the set pressure was also evaluated. Valve actuation ability was verified by review of previous test results performed during refueling outages. The test procedure provides for recording of "as-found" and "as-left" results. Testing results during the last four years (readily availaule l
for review) indicate actuation in the "as-found" condition has ranged from 1510 psig to 1565 psig. Subsequent to the initial "as-found" test, the procedure requires valve rework and "as-left" testing to a +5 psig acceptance criteria.
I Consumers Power Company therefore considers NUREG-0737, Item II.D.1 closed.
I The characteristics of the test valve have been established as sufficiently similar to conclude validity for Big Rock Point Plant. Additional considera-l tions regarding valve capacity and actuation ability were evaluated to ensure satisfactory operability and provide interim justification. Appropriate action documents have been generated to provide for relief valve spring replacement in accordance with the conclusions and recommendations of the enclosed valve comparison report by Crosby Valve & Gage Company.
Thomas C Bordine Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector-Big Rock Point pages oc0782-0012a142
-,