Bulletin 80-18: Maintenance of Adequate Minimum Flow Thru Centrifugal Charging Pumps Following Secondary Side High Energy Line Rupture
SSINS No.: 6820
Accession No.:
8005050062
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
July 24, 1980
IE Bulletin No. 80-18
MAINTENANCE OF ADEQUATE MINIMUM FLOW THRU CENTRIFUGAL CHARGING PUMPS
FOLLOWING SECONDARY SIDE HIGH ENERGY LINE RUPTURE
Description of Circumstances:
Letters similar to the May 8, 1980 notification made pursuant to Title 10
CFR Part 21 (enclosure) were sent from Westinghouse to a number of operating
plants and plants under construction (list, within enclosure) in early May,
1980.
The letters and the enclosed "Part 21" letter contain a complete description
of the potential problem summarized below. The letters indicated that under
certain conditions the centrifugal charging pumps (CCPs) could be damaged
due to lack of minimum flow before presently applicable safety injection
(SI) termination criteria are met. The particular circumstances that could
result in damage vary somewhat from plant to plant, but involve
unavailability of the pressurizer power operated relief valves (PORVs), with
operation of one or more CCPs repressurizing the reactor during SI following
a secondary system high energy line break. Since the SI signal automatically
isolates the CCP mini-flow return line, the flow through the CCPs is
determined by the individual pump characteristic head vs. flow curve, the
pressurizer safety valve setpoint, and the flow resistances and pressure
losses in the piping and in the reactor core. That minimum flow may not be
adequate to insure pump cooling, and resulting pump damage could violate
design criteria before current SI termination criteria are met.
Westinghouse recommends that plant specific calculations outlined in the
letter (enclosure) be performed to determine if adequate minimum flow is
assured under all conditions. If adequate minimum flow is not assured,
Westinghouse recommends specific equipment and procedure modifications which
will result in adequate minimum flow. The recommended modifications assure
availability of the necessary minimum flow by assuring that the mini-flow
bypass line will be open when needed, but will be closed at lower pressures
when the extra flow resulting from bypass line closure might be necessary
for core cooling.
.
IE Bulletin No. 80-18 July 24, 1980
Page 2 of 3
Actions to be taken by PWR licensees listed in the enclosure as "operating
plants," and those listed as "non-operating plants" which are nearing
licensing* are listed below:
1. Perform the calculations, outlined in the enclosure, for your plant.
2. If availability of minimum cooling flow for the CCPs is not assured for
all conditions by the calculations in 1:
a. Make modifications to equipment and/or procedures, such as those
suggested in the enclosure, to insure availability of adequate
minimum flow under all conditions. If modifications are made as
described in the attachment for interim modification II, verify
that the Volume Control Tank Relief Valve is operable and will
actuate at its design setpoint.
b. Justify that any manual actions necessary to assure adequate
minimum flow for any transient or accident requiring SI can and
will be accomplished in the time necessary.
c. Verify that any manipulations required (valve opening or closing,
along with the instrumentation necessary to indicate need for the
action or accomplishment of the action, etc.) can be accomplished
without offsite power available.
d. Justify that flow available from the CCPs with the modifications
in place will be sufficient to justify continued applicability of
any safety related analyses which take credit for flow from the
CCPs (LOCA, HELB, etc.).
e. Justify that all Technical Specifications based on the Item 2.d
analyses remain valid.
3. Provide the results of calculations performed under Item 1, and
describe any modifications made as a result of Item 2 (include the
justifications requested).
Actions to be taken by PWR licensees not listed in the enclosure are listed
below:
1. In a quantitative manner similar to 1 above, determine whether or not
minimum cooling is provided to centrifugal pumps used for high pressure
injection, for all conditions requiring SI, prior to satisfying SI
* Those listed in the enclosure considered to be "nearing licensing" are:
North Anna 2, Diablo Canyon 1, McGuire 1, Salem 2, and Sequoyah. These
plants must respond in writing within the specified time. Other
non-licensed plants whether or not listed in the enclosure, are not
required to submit a written response at this time.
.
IE Bulletin No. 80-18 July 24, 1980
Page 3 of 3
termination criteria. If a "minimum flow bypass" line is present which
remains open during high pressure injection, and if that line guarantees
that minimum cooling flow will be provided to the pumps under such
conditions, then no further calculations are required if all safety related
analyses (Item 2.d above) assumed presence of the open line.
2. Same as 2 above.
3. Same as 3 above.
Licensees of all operating PWR power reactor facilities and those nearing
licensing* shall submit the information requested within 60 days of the date
of this letter. Include in your response to this Bulletin, (a) your schedule
for any changes proposed, (b) if reactor operation is to continue prior to
completion of the proposed changes, include your justification for continued
operation.
Reports shall be submitted to the Director of the appropriate NRC Regional
Office and a copy forwarded to the Director, NRC Office of Inspection and
Enforcement, Division of Reactor Operations Inspection, Washington, D.C.
20555.
Approved by GAO, B280225 (R0072); clearance expires 7-31-80. Approval was
given under a blanket clearance specifically for identified generic
problems.
Enclosure:
Ltr from T. M. Anderson, W
to V. Stello, IE dtd 5/8/80
*Those considered to be "nearing licensing" are: North Anna 2, Diablo Canyon
1, McGuire, Salem 2, and Sequoyah.
Page Last Reviewed/Updated Tuesday, March 09, 2021