Where are valid values defined for @Scope in web-aware and portal spring contexts?

You can use string literals if you want (though global session would be "globalSession").

Alternatively, you can use constants defined in WebApplicationContext.

BeanDefinition only has SCOPE_SINGLETON and SCOPE_PROTOTYPE.

The other scopes, being only applicable to web applications, are defined in org.springframework.web.context.WebApplicationContext.

A useful list of constants can be found in the javadoc for Constant Field values.