Information Notice No. 81-12: Guidance on Order Issued January 9, 1981 Regarding Automatic Control Rod Insertion on Low Control Air Pressure
SSINS No.: 6835
Accession No.:
8011040284
IN 81-12
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
March 31, 1981
Information Notice No. 81-12: GUIDANCE ON ORDER ISSUED JANUARY 9, 1981
REGARDING AUTOMATIC CONTROL ROD INSERTION
ON LOW CONTROL AIR PRESSURE
Description of Circumstances:
The attached guidance has been provided to NRC inspectors to assist in the
verification of BWR licensee action taken in implementation of the Order
issued January 9, 1981 regarding automatic control rod insertion on low
control air pressure. This guidance may also be of interest to BWR
licensees, but does not in itself establish new or additional requirements.
No written response to this information is required. If you need additional
information regarding this matter, please contact the Director of the
appropriate NRC Regional Office.
Attachments:
1. Guidance on Order
2. Recently issued Information Notices
.
Attachment 1
IN 81-12
March 31, 1981
GUIDANCE ON ORDER
The requirements of Section IV of the January 9, 1981 Order are quoted below
with the appropriate guidance following each item.
"(1) An automatic system shall be operable to initiate control rod insertion
on low pressure in the control air header, which meets the following
criteria:"
"(a) The system shall automatically initiate control rod insertion at
10 psi or greater above scram outlet valve opening pressure."
GUIDANCE In addition to the 10 psi requirement the base setpoint
should be at least 50 psi. If the setpoint is not at least 50
psi, NRR should be informed to determine whether any further
action might be necessary.
"(b) The system shall not degrade existing safety systems (e.g.,
reactor protection system)."
GUIDANCE If the system is interconnected with the reactor protection
system, its components shall be qualified and its design
shall be safety grade (i.e., conform with applicable IEEE
standards). If the system is fully isolated or does not
interconnect with the reactor protection system, its
components shall be of a quality consistent with the
requirements of item (d) below.
"(c) The system shall allow for scram reset."
GUIDANCE Scram reset is intended to accomplish only the return of
control air and the subsequent closing of scram valves and
opening of scram discharge instrumented volume (SDIV) vent
and drain valves.
"(d) The design shall consider the potential for inadvertent or
unnecessary scrams."
GUIDANCE This consideration would suggest the use of safety grade
equipment for operational reliability reasons, but, as a
minimum, control grade equipment may be used.
"(e) Any required power supply should not be subject to any failure
mode which could also initiate the degraded-air conditions, unless
it can be demonstrated that an automatic scram will occur promptly
because of the failure mode of the power supply."
GUIDANCE This statement is self-explanatory.
"(f) The system is not subject to the requirements of Appendices A and
B of 10 CFR 50."
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Attachment 1
IN 81-12
March 31, 1981
Page 2 of 2
GUIDANCE This criterion is applicable only for those automatic dump
systems that do not interconnect with, or are fully isolated
from the reactor protection system. For systems directly
interacting with the reactor protection systems, the
requirements of Appendices A and B of 10 CFR 50 are fully
applicable.
"(g) There shall be a documented independent design review of the
system."
GUIDANCE This statement is self-explanatory with the added provision
that the conclusion reached will not include any unreviewed
safety question.
"(h) Before the system is declared operable, a documented
preoperational test of the system will be successfully completed."
GUIDANCE An integrated system test should be performed in every case.
For those plants that remain operating and cannot perform a
fully integrated test, demonstration of the portions of the
system is a satisfactory test until an integrated test can be
performed at the earliest outage for any purpose.
"(i) The system shall be functionally tested at each unit shutdown, but
not be tested more than once each 90 days."
GUIDANCE This statement is self-explanatory.
"(2) After April 9, 1981, the Automatic Dump System as described above shall
be operable in all modes other than shutdown and refueling or the unit
shall be placed in a cold shutdown condition within 72 hours unless
system operability is restored."
GUIDANCE This statement is self-explanatory.
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