ML19221A852
| ML19221A852 | |
| Person / Time | |
|---|---|
| Issue date: | 02/17/1972 |
| From: | NRC OFFICE OF STANDARDS DEVELOPMENT |
| To: | |
| References | |
| REGGD-01.022, REGGD-1.022, NUDOCS 7907100108 | |
| Download: ML19221A852 (3) | |
Text
.4 2/17/72 SAFETY GUIDE 22 PERIODIC TESTING OF PROTECTION SYSTEM ACTUATION FUNCTIONS A.
Introduction such as reactor inp, containment General Design Criterion 20 of Appendix A isolation, or eme:gency coola nt to 10 CFR Part 50," General Design Cntena for irtection. The followmg are examples Nuclear Power Plants," requires that the of actuated equipment: an entire protection system be designed to initiate the control rod and its release mechanism, operation of systems and components important a cunzainment isolation valve and its to safety. General Design Criterion 21 requires operator, and a safety iruection pump and its crime mover.
tlut the protection system be designed to permit penodic testing of its functioning when the C.
Discussion reactor is in operation. In current designs the ability of the protection system to initiate the One function of the protection system is to operation of safety systems depends on the initiate the o peration of systems and proper performance of actuation devices; components important to safety. It is required therefore, these devices are to be tested. This that the protection system be designed to permit safety guide desenbes acceptable methods of periodic testing of its ability to perform these including the actuation devices in the periodic initiation functions when the reactor is in tests of the protection system dunng redor operation. Based on the review of several operation. It does not address the frequency of applications for construction permits and such testing.
operating licenses, th' regulatory staff has concluded that the eferable method of B.
Definitions implementing this req ient is to design the protection system such that the actuation Protection System: The protection system, devices and actuated equipment are periodically as defined in IEEE Std 279-1971,8 tested with the protection system dunng reactor encompasses all electric and mechanical operation.
devices and circuitry (from sensors to Generally it has been industry practice to a c t u a tion device input terminals) include the actuation devices in the periodic involved in generating those signals tests of that portion of the protection system associated with tne protective function. used to initiate reactor trip. Early designs did not provide this same degree of testability in A c t u a tion Device: A component or assembly of components that directly those portions of the protection systern used to controls the mouve power (electricity, initiate the operation of engineered safety compressed air, etc.) for actuated features, standby power supplies, and other equipment. He following are examples supporting syste ms. It is recognized that of an actuation device: a circuit providing the capability to test the actuation breaker, a relay, and a valve (and its devices for these latt:r rystems can present operator) used to control compressed different design problems. Nevertheless, General air to the operator of a containment Design Criterion 21 requires the same high isolation valve.
degree of inservice testatility in all portions of Actuated Equipment: A component or the protection system.
assembly of components that performs In the case of some engineered safet) or directly contnbutes to the feature systems, testing the operation of the performance of a protective function entire group of actuated equipment associated with a protective function may damage plant e9uipment or disrup reactor operation. In thesc
' Copies of IEEF Std 279 1971, "Cmens for cases, acceptable n.ethods of including the Proteomn syvems for Nuclear Po or Generat ng actuation devices in penodic tests of the Si si m ot,"
may be obtained from the Institute of Electricul and Llectronics Engineers, United Engineering protection system, while avoiding the Center,.45 East 47th Street, New York, New York undesirable effects of operation of the actuated 10017-equipment, Pre: (1) testing the actuation devices 125 106 g 907100lD8 211
h. _..
and t he as tuated egnpment individually or in b.
The protection system and the 2
indicunnly selected groupt 12 s preventing the sy ste ms w hose o peratmn it operation of tertain actuated equipment dunng imtiates should be designed to
.i test oi their at t ua tio n devices, and (3) pe rmit testing of the actuation Jesigning the Ptem such that operation of the devices during reactor operation.
at tuated equipment requires the operation of 2.
Acceptable methods of including the more than one actuation deuce, each actuation actuation deuces m the periodic tests deuce being mdividually testable. Examples of of the protection sy; tem are uhhzation of these methods are, respectively:
a.
T e s ting simultaneouso all iI) t esting the ac tuation desice for a actuation devices and actuated containment s;,ra) pump separaid) fror.. u.e mmpment m aud with each a ct ua t io n deuces for the containment spray redundant p r o tection system sahet (2) moung the circuit breaker for an utput ugnal.
emergency coolant pump to a test position that b.
Testmg all actuatmn Jmces and pr e s e n t s power beine supphed to the pump actuated eqmpment miuduah or durmg a test closure o! its circuit breaker, and
- b**
(M r est m g mdindually the two solenoid c.
Preventmg the operation of certain operat ed u hes that. :t in coincidence to actuaW eppment Mng a ten control compressed air to an isolation valve.
of then aduation &ucen Compared to a design that permits testing d.
Proujing the actuated equipment the operation of all deuces associated with each with more than one actuation protection system output signal, each of the device and testmg mdividually each methods discussed above can have two major actuation vi disadvantages. Ftrst, the abihty of a system to respond to a bona fide accident signal may be prefer ble method of including the partially or completely bypassed. In this case, actuation devices in the penodic tests the design should include provisions that prevent of the protection sys*.,n. It shall be a wrr.p!cte bypass of any protective function n ted that the acceptabi!!ty of each of and indicate the status of the protection system.
the four above methods is conditioned The second major disadvantage is that certain by the provisionsof regulatory positions actuated equipment may not be tested during
- 3. and 4. below.
reactor operation. In th2s case, it should be 3.
Where the ability of a system to shown that there are compalhng reasons for not testmg the act ua ted equipment and the respond to a bona fide accident signal is probability that the protection system will fail intentionally bypassed for the purpose to mitiate their operation is acceptably low.
of perf rming a test dunng reactor operation:
D.
Regulatory Position a.
Positive means should be provided to prevent expansion of the bypass 1.
The protection system shc uid be condition to redundant or diverse designed to permit periodic testing to systems, and extend to and include the actuation Bch bypass condi~ tion should be devices and actuated equipment.
in dividually and automatically a.
The periodic tests shouId indicated to the reactor operator in duphcate, as closely as practicable, the main control room.
the performance that is required of-4.
Where actuated equipment is not tested the actuation devices in the event during reactor operation, it should be of an accident.
shown that-a.
There is no practicable system
'The actuated equipment is included m the periodic design that would permit operation tesis to provide assurance that the prntection system can of the actuated equipment without inihate its operation, as required by Ge:ern! Design adversely affecting the safety or Cotenon 21. t his safety guide does noi Vdrars the operabihty of the plant; lunctional performance testmg of actuated eculprnent required by other General Design Criteria, neither does it b.
The probability that the protection preclude a design that fulfuls more than one testmg system will fail to initiate the requirement with a stngle test.
operation of the a c t u a ted 125 107 22.2
equipment is, and can be operation, and maintained, a ccept ably low e.
The actuated equipment can be without testing the actuated routinely tested when the reactor equipment during reactor is shut down.
O O
us m 22.3